Happening @ Michigan https://events.umich.edu/list/rss RSS Feed for Happening @ Michigan Events at the University of Michigan. Physics Graduate Student Symposium (PGSS) | Miniaturized Frequency Combs Enable Advanced Spectroscopies to Leave the Lab and (Maybe) Enter Orbit (August 22, 2019 12:00pm) https://events.umich.edu/event/65404 65404-16595537@events.umich.edu Event Begins: Thursday, August 22, 2019 12:00pm
Location: West Hall
Organized By: Department Colloquia

Frequency Combs, or pulsed lasers which are capable of emitting many narrow and closely spaced spectral lines (teeth) with fixed phase relationships between adjacent teeth, are an essential tool in precision metrology and spectroscopy. Their usefulness comes from the fact that their entire spectrum can be controlled by just adjusting the time between pulses and the pulse-to-pulse phase slip of their electric field. This means that, using relatively simple control schemes, frequency combs enable the most precise measurements of time and frequency possible, among a plethora of other applications. Typically, however, these light sources are roughly the size of a kitchen table and require the high stability of a lab environment to maintain the controllability of their output. Miniaturized combs exist, in the form of microscopic ring resonators, but these light sources are not very tunable, typically require large and powerful pump lasers to operate, and are expensive to manufacture. These drawbacks are all showstoppers when it comes to allowing frequency comb enabled precision measurement and spectroscopy to leave the lab. We have demonstrated a new, extremely cheap, simple, and low power laser diode-based frequency comb which is roughly the size of a grain of rice. This laser can be battery powered, and its spectrum is highly controllable, making it an ideal light source to allow advanced precision measurement and spectroscopy to leave the lab. In my talk, I will give a brief overview of frequency comb-based measurements, demonstrate the stability and tunability of our new sources, and outline their prospect for future ground- and space-based applications.

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Conference / Symposium Mon, 19 Aug 2019 08:51:15 -0400 2019-08-22T12:00:00-04:00 2019-08-22T13:00:00-04:00 West Hall Department Colloquia Conference / Symposium West Hall
Special Physics Colloquium | State of Department Address (September 4, 2019 4:00pm) https://events.umich.edu/event/65753 65753-16651991@events.umich.edu Event Begins: Wednesday, September 4, 2019 4:00pm
Location: West Hall
Organized By: Department Colloquia

Physics Professor and Chair David Gerdes will welcome faculty, staff, and students to the 2019-20 school year and talk about different aspects of the Physics Department.

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Presentation Mon, 26 Aug 2019 12:00:36 -0400 2019-09-04T16:00:00-04:00 2019-09-04T17:00:00-04:00 West Hall Department Colloquia Presentation West Hall
CM Theory Seminar | Gate-Accessible Superconductivity and Helical Modes in Monolayer WTe_2 (September 5, 2019 4:00pm) https://events.umich.edu/event/65277 65277-16565496@events.umich.edu Event Begins: Thursday, September 5, 2019 4:00pm
Location: West Hall
Organized By: Department of Physics

Quantum materials research aims to uncover exotic physics and new approaches toward applied technologies. Two-dimensional crystals consisting of individual layers of van der Waals materials provide an exciting platform to study correlated and topological electronic states. These same crystals can be flexibly restacked into van der Waals heterostructures, which enable clean interfaces between heterogeneous materials. Such heterostructures enable the isolation and protection of air sensitive 2D materials as well as provide new degrees of freedom for tailoring electronic structure and interactions. In this talk, I will present experimental work studying electronic transport in monolayer WTe_2. First, un-doped monolayer WTe_2 exhibits behaviors characteristic of a 2D topological insulator, including edge mode transport approaching the quantum of conductance up to nearly 100 Kelvin. Second, we have discovered that the same monolayers display superconductivity at low carrier densities accessible by local field-effect gating through a low-κ dielectric. The concurrence of electrostatically accessible superconductor and topological insulator phases in the same 2D crystal allows us to envision a new model of gate-configurable topological electronic devices.

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Workshop / Seminar Thu, 05 Sep 2019 18:16:13 -0400 2019-09-05T16:00:00-04:00 2019-09-05T17:00:00-04:00 West Hall Department of Physics Workshop / Seminar West Hall
Statistics Department Seminar Series: Gongjun Xu, Assistant Professor, Department of Statistics, University of Michigan (September 6, 2019 10:00am) https://events.umich.edu/event/63880 63880-15977781@events.umich.edu Event Begins: Friday, September 6, 2019 10:00am
Location: West Hall
Organized By: Department of Statistics

Latent class models have wide applications in social and biological sciences. In many applications, pre-specified restrictions are imposed on the parameter space of latent class models, through a design matrix, to reflect practitioners' diagnostic assumptions about how the observed responses depend on the respondents' latent traits. Though widely used in various fields, such restricted latent class models suffer from nonidentifiability due to the models' discrete nature and complex restricted structure. This talk addresses the fundamental identifiability issue of restricted latent class models by developing a general framework for strict and partial identifiability of the model parameters. The developed identifiability conditions only depend on the design matrix and are easily checkable, which provides useful practical guidelines for designing statistically valid diagnostic tests. Furthermore, the new theoretical framework is applied to establish, for the first time, identifiability of several designs from cognitive diagnosis applications.

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Workshop / Seminar Wed, 28 Aug 2019 13:35:05 -0400 2019-09-06T10:00:00-04:00 2019-09-06T11:00:00-04:00 West Hall Department of Statistics Workshop / Seminar Xu, Gongjun
Quantitative Biology Seminar | Timeseries Analysis of Stochastic Systems with Hidden Components (September 9, 2019 12:00pm) https://events.umich.edu/event/66309 66309-16727886@events.umich.edu Event Begins: Monday, September 9, 2019 12:00pm
Location: West Hall
Organized By: Department of Physics

Despite dramatic advances in experimental techniques, many facets of intracellular dynamics remain hidden, or can be measured only indirectly. In this talk, I will describe two strategies to analyze stochastic timeseries data from biological systems with hidden parts: replacement of multi-step process with a time delay distribution or quasi-steady-state. Then, I will illustrate how these strategies are applied to understand the processes of protein synthesis, which involves multiple steps such as transcription, translation, folding and maturation, but typically whose intermediates proteins cannot be measured. Furthermore, drugs are also cleared out from our body in multiple steps of metabolism. To estimate the rate of drug clearance, which is a critical factor determining the dose level, a canonical approach has been used in more than 65,000 published papers for last 30 years. I will point out the critical limitation of the canonical approach and propose an alternative approach, which leads to accurate and precise estimation of drug clearance rate.

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Workshop / Seminar Mon, 09 Sep 2019 18:16:27 -0400 2019-09-09T12:00:00-04:00 2019-09-09T13:00:00-04:00 West Hall Department of Physics Workshop / Seminar West Hall
HEP-Astro Seminar | Intergalactic Medium-based Cosmology: from BOSS to DESI (September 9, 2019 4:00pm) https://events.umich.edu/event/64645 64645-16404981@events.umich.edu Event Begins: Monday, September 9, 2019 4:00pm
Location: West Hall
Organized By: Department of Physics

Intergalactic Medium (IGM)-based cosmology established itself as a solid cosmological probe with the wide success of the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS). With the Dark Energy Spectroscopic Instrument (DESI) survey starting imminently, we are taking a look at the accomplishments of SDSS-III with regards to IGM-based cosmology and discussing exciting science and new statistical challenges in the era of DESI.

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Workshop / Seminar Mon, 09 Sep 2019 18:16:27 -0400 2019-09-09T16:00:00-04:00 2019-09-09T17:00:00-04:00 West Hall Department of Physics Workshop / Seminar West Hall
Department Colloquium | From Hadrons to Hidden Assumptions: My Recent Work in Quantum Chromodynamics and Foundations of Physics (September 11, 2019 4:00pm) https://events.umich.edu/event/65278 65278-16565497@events.umich.edu Event Begins: Wednesday, September 11, 2019 4:00pm
Location: West Hall
Organized By: Department of Physics

Two recently initiated directions in my research will be discussed. I will present the first results from a new program at the LHCb experiment at CERN to study hadronization, i.e. how subnuclear particles called quarks and gluons form strong force bound states in quantum chromodynamics. These studies at LHCb over the upcoming decade will drive ideas about how to investigate various hadronization mechanisms further at the future Electron-Ion Collider, proposed for construction in the U.S. in the 2020s. I will additionally give an overview of a project exploring the foundations of physics that aims to find a set of minimal assumptions from which the known laws of physics can be rederived. Pinpointing the conditions under which the different branches of physics are valid should give a better understanding of them and may in turn provide new insights for future theories.

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Workshop / Seminar Wed, 11 Sep 2019 18:16:31 -0400 2019-09-11T16:00:00-04:00 2019-09-11T17:00:00-04:00 West Hall Department of Physics Workshop / Seminar West Hall
CM Theory Seminar | Topological and Fractional Electronic States in Graphene Heterostructures (September 12, 2019 4:00pm) https://events.umich.edu/event/66185 66185-16719558@events.umich.edu Event Begins: Thursday, September 12, 2019 4:00pm
Location: West Hall
Organized By: Department of Physics

Graphene is a highly tunable platform for studying the effects of electron-electron interactions in two dimensions. Encapsulation with a 2D dielectric (hexagonal boron nitride, hBN), and more recently the use of single-crystal graphite top and bottom gates have decreased the electronic disorder to a level suitable for the to study fragile and exotic strongly correlated states. Additionally, control of twist angle between closely-matched crystal lattices allows for unique control of electronic properties, leading to the “Hofstadter butterfly” and more recently unconventional superconductivity. I will describe newly discovered exotic fractional quantum Hall states and a class of related states called fractional Chern insulators, both in high quality graphene heterostructures. These measurements show that graphene is an intriguing platform for realizing new topological and fractional phases, and opens new routes towards realizing interesting quantum phase transitions and manipulating non-abelian quasiparticles for quantum computation.

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Workshop / Seminar Thu, 12 Sep 2019 18:16:34 -0400 2019-09-12T16:00:00-04:00 2019-09-12T17:00:00-04:00 West Hall Department of Physics Workshop / Seminar West Hall
Statistics Department Seminar Series: Kengo Kato, Associate Professor, Department of Statistics and Data Science, Cornell University (September 13, 2019 10:00am) https://events.umich.edu/event/63881 63881-15977782@events.umich.edu Event Begins: Friday, September 13, 2019 10:00am
Location: West Hall
Organized By: Department of Statistics

In this talk, I will discuss inference for the mean vector of a high
dimensional U-statistic. In the era of Big Data, the dimension of the U statistic and the sample size of the observations tend to be both large, and the computation of the U-statistic is prohibitively demanding. Data-dependent inferential procedures such as the empirical bootstrap for U-statistics is even more computationally expensive. To overcome such computational bottleneck, we introduce randomized incomplete U-statistics with sparse weights whose computational cost can be made independent of the order of the U-statistic. We derive non-asymptotic Gaussian approximation error bounds for the randomized incomplete U-statistics in high dimensions, namely in cases where the dimension is possibly much larger than the sample size, for both non-degenerate and degenerate kernels. In addition, we propose generic bootstrap methods for the incomplete U-statistics that are computationally much less demanding than existing bootstrap methods and establish finite sample validity of the proposed bootstrap methods. If time permits, I will also discuss the extension to infinite order U-statistics.

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Workshop / Seminar Wed, 04 Sep 2019 09:24:45 -0400 2019-09-13T10:00:00-04:00 2019-09-13T11:00:00-04:00 West Hall Department of Statistics Workshop / Seminar Kato,Kengo
HET Seminar | Aspects of five-dimensional superconformal field theories (September 13, 2019 3:00pm) https://events.umich.edu/event/66678 66678-16770193@events.umich.edu Event Begins: Friday, September 13, 2019 3:00pm
Location: West Hall
Organized By: Leinweber Center for Theoretical Physics

Five-dimensional superconformal field theories (5d SCFTs) play an interesting role in the general understanding of quantum field theory. They often provide strongly-coupled UV fixed points with remarkable features for perturbatively non-renormalizable gauge theories, which makes them interesting in their own right. Moreover, prominent lower-dimensional theories can be obtained by compactification from five-dimensional parent theories, and this perspective has led to numerous new insights. A fruitful interplay between string theory and quantum field theory methods has led to a coherent and thorough understanding of 5d SCFTs, and I will review recent developments in this context.

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Lecture / Discussion Thu, 12 Sep 2019 14:54:53 -0400 2019-09-13T15:00:00-04:00 2019-09-13T16:00:00-04:00 West Hall Leinweber Center for Theoretical Physics Lecture / Discussion West Hall
HEP-Astro Seminar | A Deep Learning Approach to Galaxy Cluster X-ray Masses (September 16, 2019 4:00pm) https://events.umich.edu/event/64708 64708-16428919@events.umich.edu Event Begins: Monday, September 16, 2019 4:00pm
Location: West Hall
Organized By: Department of Physics

I will present a machine-learning approach for estimating galaxy cluster masses from Chandra x-ray mock observations. I will describe how a Convolutional Neural Network (CNN) -- a deep machine learning tool commonly used in image recognition tasks -- can be used to infer cluster masses from these images, reducing scatter in the mass estimates by up to 50%. I will also show an interpretation tool, inspired by Google DeepDream, that can be used to gain some physical insight into what the CNN sees.

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Workshop / Seminar Mon, 16 Sep 2019 18:16:47 -0400 2019-09-16T16:00:00-04:00 2019-09-16T17:00:00-04:00 West Hall Department of Physics Workshop / Seminar West Hall
CM-AMO Seminar | Controlling Light Matter Interactions in Layered Materials with Conventional and Topological Band Structures (September 17, 2019 4:00pm) https://events.umich.edu/event/66791 66791-16778979@events.umich.edu Event Begins: Tuesday, September 17, 2019 4:00pm
Location: West Hall
Organized By: Department of Physics

Strongly confined electrical, optical and thermal excitations drastically modify material's properties and break local symmetries that can enable precisely tunable responses and new functionalities. We will discuss the effect of engineered plasmonic lattice on light matter interactions in 2D excitonic crystals to produce novel responses such as enhanced and tunable emission, Fano resonances and strong exciton-plasmon polaritons, which can be precisely controlled by geometry and applied fields to produce new device concepts. Our recent work on collective polaritonic modes and the formation of a complete polaritonic bandgap in few-layered excitonic semiconductors coupled to plasmons will also be presented along with our ability to control them via externally applied electric fields.

We will also discuss our efforts to explore the optoelectronic properties of Mo_x W_{1-x} Te_2, which are type-II Weyl semimetals, i.e., gapless topological states of matter with broken inversion and/or time reversal symmetry, which exhibit unconventional responses to externally applied fields. We have observed spatially dispersive circular photogalvanic effect (s-CPGE) over a wide spectral region (0.2 - 2.0 eV range) in these materials. This effect shows exclusively in the Weyl phase and vanishes upon temperature induced topological phase change. Since the photon energy leads to interband transitions between different electronic bands, we use the density matrix formalism to describe the photocurrent response under chiral optical excitation with a spatially inhomogeneous beam. We will discuss how spatially inhomogeneous optical excitation and unique symmetry and band structure of Weyl semimetals produces CPGE in these systems. The effect of band inversion, Berry curvature and asymmetric carrier relaxation in this material system on the s-CPGE signal will also be discussed along with the implications for designing new and unconventional optoelectronic devices.

Short Biography:
Ritesh Agarwal is a Professor in the Department of Materials Science and Engineering at the University of Pennsylvania. He earned his undergraduate degree from the Indian Institute of Technology, Kanpur in 1996, and a master’s degree from the University of Chicago. He received his PhD in physical chemistry from University of California at Berkeley in 2001 researching liquid and protein solvation and photosynthesis via nonlinear optical techniques. After completing his PhD., Ritesh was a postdoctoral fellow at Harvard where he studied the photonic properties of semiconductor nanowires. His current research interests include structural, chemical, optical and electronic properties of low-dimensional systems. Ritesh is the recipient of the NSF CAREER award in 2007, NIH Director’s New Innovator Award in 2010 and the SPIE Nanoengineering Pioneer Award in 2014. In 2017 he became the director of a Multi-University Research Initiative on Phase Change Materials for Photonics, leading a team of six PIs from five universities.

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Workshop / Seminar Tue, 17 Sep 2019 18:17:16 -0400 2019-09-17T16:00:00-04:00 2019-09-17T17:00:00-04:00 West Hall Department of Physics Workshop / Seminar West Hall
Statistics Department Seminar Series: Mohamad Kazem Shirani Faradonbeh, Postdoctoral Researcher, University of Florida (September 17, 2019 4:00pm) https://events.umich.edu/event/66172 66172-16751227@events.umich.edu Event Begins: Tuesday, September 17, 2019 4:00pm
Location: West Hall
Organized By: Department of Statistics

Abstract:
Vector Auto-Regressive (VAR) models are widely used in different applications ranged from econometrics to engineering. The problem of learning the unstable transition matrix of the model is of interest, e.g. for forecasting hyperinflation episodes and stock market bubbles. Especially, a non-asymptotic analysis is required for specifying the roles of sample size, problem dimension, innovation (noise) distribution, and key characteristics of the underlying data generation mechanisms.

In this setting, the Gram matrix of the observed variables randomly diverges, wildly explodes, and is dramatically ill-conditioned. So, the existing approaches based on concentration or mixing time-series are inapplicable. Also importantly, recent studies discovered a new condition for explosive processes that is necessary for accurate learning; being called "regularity" of the transition matrix. In this talk, we present the first set of finite-sample results for the least-squares estimates of the unstable time series with heavy-tailed innovations, and fully quantify the regularity. We also mention novel approaches for studying the "anti-concentration" properties of the underlying random matrices, being used to obtain the presented results.

Further discussions consist of learning the unknown model for planning purposes. That is, designing data-driven input signals which can stabilize the time series, while matrices encoding the evolution of the process and the influence of the input signals, are unknown. The first algorithm for fast stabilization under uncertainty is introduced, with theoretical performance guarantees being established. In order to ensure consistency of estimation, the proposed procedure utilizes two methods of employing random matrices in the design of the exogenous inputs; (i) stochastic feedback, and (ii) stochastic parameter. Numerical examples indicating the effects of both the magnitude and the frequency of the randomizations are provided.

Bio:
Mohamad Kazem Shirani Faradonbeh
is currently a Post-Doctoral Research Associate with the Informatics Institute and the Department of Statistics
at the University of Florida. He received the Ph.D. degree in Statistics from the University of Michigan in 2017, under the supervision of Ambuj Tewari and George Michailidis. Before that, he was an undergraduate student in the Department of Electrical Engineering, Sharif University of Technology. His research interests include sequential statistical analysis, reinforcement learning, data-driven intelligent tutoring, and control of network systems.

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Workshop / Seminar Sat, 07 Sep 2019 09:49:06 -0400 2019-09-17T16:00:00-04:00 2019-09-17T17:00:00-04:00 West Hall Department of Statistics Workshop / Seminar Mohamad Kazem Shirani Faradonbeh
Department Colloquium (September 18, 2019 4:00pm) https://events.umich.edu/event/67172 67172-16805254@events.umich.edu Event Begins: Wednesday, September 18, 2019 4:00pm
Location: West Hall
Organized By: Undergrad Physics Events

Department Colloquium

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Workshop / Seminar Fri, 13 Sep 2019 16:21:49 -0400 2019-09-18T16:00:00-04:00 2019-09-18T17:00:00-04:00 West Hall Undergrad Physics Events Workshop / Seminar West Hall
Department Colloquium | Advancing CMB Cosmology: ACTPol, Simons Observatory, and CMB-S4 (September 18, 2019 4:00pm) https://events.umich.edu/event/65279 65279-16565498@events.umich.edu Event Begins: Wednesday, September 18, 2019 4:00pm
Location: West Hall
Organized By: Department of Physics

Measurements of the cosmic microwave background (CMB) are a powerful probe of the origin, contents, and evolution of our Universe. CMB measurements continue to improve according to a Moore’s law under which the mapping speed of experiments improves by an order of magnitude roughly every five years. This rapid progression in our ability to measure the CMB has translated into a series of scientific advances including showing our universe to be spatially flat, constraining inflationary and alternative theories of the primordial universe, and providing a cornerstone for our precision knowledge of the Lambda-CDM model. Observations with the current generation of experiments, including Advanced ACTPol, will soon produce improved cosmological constraints. Building on this work, in the coming decade Simons Observatory and ultimately CMB-S4 will: pass critical thresholds in constraints on inflation and light relativistic species; provide improved measurements of dark energy, dark matter, neutrino masses, and a variety of astrophysical phenomena; and enable searches for new surprises.

In this talk I present the design and status of measurements with Advanced ACTPol and how we are building on this work to realize the next generations of experiments including Simons Observatory and CMB-S4. I will highlight the technological advances that underlie the rapid progress in measurements including: polarization sensitive detectors which simultaneously observe in multiple colors; metamaterial antireflection coated lenses and polarization modulators; and overall advances in experimental design. I will present preliminary new results from ACTPol and conclude with science forecasts for the coming decade.

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Workshop / Seminar Wed, 18 Sep 2019 18:17:13 -0400 2019-09-18T16:00:00-04:00 2019-09-18T17:00:00-04:00 West Hall Department of Physics Workshop / Seminar West Hall
CM Theory Seminar | Fracton Phase of Matter: From Fantasy to Reality (September 19, 2019 4:00pm) https://events.umich.edu/event/65861 65861-16662139@events.umich.edu Event Begins: Thursday, September 19, 2019 4:00pm
Location: West Hall
Organized By: Department of Physics

Fracton phase of matter shares many features of topological order, including long-range entangled ground states and non-trivial braiding statistics. At the same time, fracton phase contains subextensive ground-state degeneracy and the restricted mobility of quasiparticle which exclude itself from the TQFT paradigm. In this talk, I will present a theoretical framework on higher rank Chern-Simons theory in 3D as the low energy effective theory for Fracton phases. In addition, I will mention the emergent fractonic phenomenon in plaquette paramagnetic crystal which prompts an algebraic quantum liquid phase with a 'bose Fermi surface'.

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Workshop / Seminar Thu, 19 Sep 2019 18:17:13 -0400 2019-09-19T16:00:00-04:00 2019-09-19T17:00:00-04:00 West Hall Department of Physics Workshop / Seminar West Hall
HET Seminar | The Future Frontier of Higgs Physics (September 20, 2019 3:00pm) https://events.umich.edu/event/67023 67023-16796448@events.umich.edu Event Begins: Friday, September 20, 2019 3:00pm
Location: West Hall
Organized By: Leinweber Center for Theoretical Physics

I will summarize what we don't already know about the 125 GeV Higgs boson and discuss directions for future investigation.

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Lecture / Discussion Thu, 12 Sep 2019 12:29:25 -0400 2019-09-20T15:00:00-04:00 2019-09-20T16:00:00-04:00 West Hall Leinweber Center for Theoretical Physics Lecture / Discussion West Hall
The Michigan Anthropology Colloquia Series: "Excavating Contentious Muslim-Christian Encounters in Mali" (September 20, 2019 3:00pm) https://events.umich.edu/event/62988 62988-15528500@events.umich.edu Event Begins: Friday, September 20, 2019 3:00pm
Location: West Hall
Organized By: Department of Anthropology

"At the dawn of French colonialism, Muslims were a minority among colonial subjects in what is present-day Mali, and Muslim missionaries flourished in the wake of the colonial peace, successfully Islamizing many colonial subjects. Entering this dynamic scene of mass Islamization, the Roman Catholic missionary order, the Missionaires d’Afrique or White Fathers, attempted with little success to bring Catholicism to Muslims and non-Muslims. Drawing on written and archival sources as well as ethnography, the paper focuses on the White Fathers’ mission activities and contentious Muslim-Christian encounters, which have echoes in oral history and the contemporary social imaginary."

The Michigan Anthropology Colloquia Series presents speakers on current topics in the field of anthropology

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Lecture / Discussion Mon, 16 Sep 2019 12:52:58 -0400 2019-09-20T15:00:00-04:00 2019-09-20T17:00:00-04:00 West Hall Department of Anthropology Lecture / Discussion West Hall
Special AMO Seminar | Quantum Optics with Molecules (September 23, 2019 12:00pm) https://events.umich.edu/event/66867 66867-16781211@events.umich.edu Event Begins: Monday, September 23, 2019 12:00pm
Location: West Hall
Organized By: Department of Physics

Recent experimental progress in the collective strong coupling regime of organic molecules with optical cavity or plasmonic modes has shown light-induced modifications of material properties. Experimental and theoretical endeavors go in the direction of charge and energy transport, Förster resonance energy transfer (FRET) enhancement, modified chemical reactivity etc. Oftentimes experiments rely on theoretical models developed for standard cavity quantum electrodynamics with two-level quantum emitters. Molecular systems however have an increased complexity as molecular vibrations and level disorder play a crucial role. We provide a theoretical formalism to tackle the light-electronic-vibrations dynamics modeled via the Holstein-Tavis-Cummings Hamiltonian [1]. We analytically describe aspects such as: polariton asymmetry, molecular branching ratio modification in the Purcell regime and cavity-mediated donor-acceptor FRET processes.

[1] M. Reitz, C. Sommer and C. Genes, Langevin approach to quantum optics with molecules, Phys. Rev. Letts 122, 203602 (2019)

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Workshop / Seminar Mon, 23 Sep 2019 18:17:04 -0400 2019-09-23T12:00:00-04:00 2019-09-23T13:00:00-04:00 West Hall Department of Physics Workshop / Seminar West Hall
HEP-Astro Seminar | Doping Xenon - Performance Enhanced Dark Matter Detectors (September 23, 2019 4:00pm) https://events.umich.edu/event/65417 65417-16597551@events.umich.edu Event Begins: Monday, September 23, 2019 4:00pm
Location: West Hall
Organized By: Department of Physics

After a series of null results from the LHC and large direct detection experiments, dark matter remains frustratingly mysterious, and much of the canonical heavy WIMP parameter space is now ruled out. In this talk, I will summarize the current state of the field of dark matter direct detection, and discuss an idea to expand the parameter space that can be probed by large liquid xenon TPCs like the LUX-ZEPLIN (LZ) detector by a adding hydrogen to the target, opening up sensitivity to WIMP masses well below 1 GeV.

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Workshop / Seminar Mon, 23 Sep 2019 18:17:04 -0400 2019-09-23T16:00:00-04:00 2019-09-23T17:00:00-04:00 West Hall Department of Physics Workshop / Seminar West Hall
CM-AMO Seminar | From Floquet Real to Imaginary Time Crystal (September 24, 2019 4:00pm) https://events.umich.edu/event/64762 64762-16444919@events.umich.edu Event Begins: Tuesday, September 24, 2019 4:00pm
Location: West Hall
Organized By: Department of Physics

Quantum time crystal has been an intriguing many-body “time” state that has received much attention and debate since its early prediction. In this talk, first, I will construct a class of concrete “clean” Floquet models to answer the open question on the role of disorder and many-body localization. Second, by observing the equivalent role of the space and imaginary time in the path integral formalism, I will present the finding that hard-core bosons coupled to a thermal bath may exhibit the order of “imaginary spacetime crystal”.

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Workshop / Seminar Tue, 24 Sep 2019 18:17:03 -0400 2019-09-24T16:00:00-04:00 2019-09-24T17:00:00-04:00 West Hall Department of Physics Workshop / Seminar West Hall
Department Colloquium (September 25, 2019 4:00pm) https://events.umich.edu/event/67173 67173-16805255@events.umich.edu Event Begins: Wednesday, September 25, 2019 4:00pm
Location: West Hall
Organized By: Undergrad Physics Events

Department Colloquium

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Workshop / Seminar Fri, 13 Sep 2019 16:25:04 -0400 2019-09-25T16:00:00-04:00 2019-09-25T17:00:00-04:00 West Hall Undergrad Physics Events Workshop / Seminar West Hall
Department Colloquium | New Realms in Coherent Light-Matter Interactions (September 25, 2019 4:00pm) https://events.umich.edu/event/65280 65280-16565499@events.umich.edu Event Begins: Wednesday, September 25, 2019 4:00pm
Location: West Hall
Organized By: Department of Physics

Light-matter interactions are at the heart of quantum electrodynamics and underpin modern photonic technologies. As we develop means to control the properties of light, matter and their interactions, intriguing new phenomena emerge. Using a designer polariton platform we have developed, we reveal a long sought after Bardeen-Cooper-Schrieffer like phase in a particle-hole-photon strongly-coupled system. Coupling two trapped polariton condensates through both coherent tunneling and incoherent dissipation, we form a model system of rich nonlinear dynamics where new, equidistant frequency lines emerge via the limit cycles at Hopft bifurcation. Using two-dimensional monolayer crystals with exceptionally strong light-matter interactions, we control the exciton-photon interactions from the incoherent limit to the coherent limit with simple mirrors and laser pulses, showing the promise of the system for photonic applications based on coherent light-matter interactions. Combining different monolayers to form atomically-thin heterostructures, we obtain a platform that allows versatile control over both the photon modes and matter excitations, where we create long-lived valley excitons, ultra-thin lasers, and moire-lattice induced hybrid dipolar excitons and polaritons.

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Workshop / Seminar Wed, 25 Sep 2019 18:17:20 -0400 2019-09-25T16:00:00-04:00 2019-09-25T17:00:00-04:00 West Hall Department of Physics Workshop / Seminar West Hall
Michael Woodroofe Lecture Series: Cun-Hui Zhang, Distinguished Professor, Department of Statistics and Biostatistics, Rutgers University (September 27, 2019 10:00am) https://events.umich.edu/event/63882 63882-15977784@events.umich.edu Event Begins: Friday, September 27, 2019 10:00am
Location: West Hall
Organized By: Department of Statistics

We consider several problems in areas where Michael Woodroofe has made seminal contributions to. In higher criticism, we develop a one-sided sequential probability ratio test based on the ordered p-values to achieve optimal detection of rare and weak signals. This makes an interesting connection to the test of power one and nonlinear renewal theorem. In multiple isotonic regression, a block estimator is developed to attain minimax rate for a wide range of signal-to-noise ratio, to achieve adaptation to the parametric root-n rate up to a logarithmic factor in the case where the unknown mean is piecewise constant, and to achieve adaptation in variable selection. In uncertainty quantification, we develop second order Stein formulas for statistical inference in nonparametric and high-dimensional problems. Applications of the second order Stein method include exact formulas and upper bounds for the variance of risk estimators and risk bounds for regularized or shape constrained estimators and related degrees of freedom adjustments and confidence regions.

*Hors d'oeuvres immediately following in 337 West Hall (Don Meyer Commons)

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Workshop / Seminar Tue, 24 Sep 2019 09:54:20 -0400 2019-09-27T10:00:00-04:00 2019-09-27T11:00:00-04:00 West Hall Department of Statistics Workshop / Seminar Zhang,Cun-Hui
Life In Graduate School | Computational Resources at Michigan (September 27, 2019 12:00pm) https://events.umich.edu/event/67234 67234-16828994@events.umich.edu Event Begins: Friday, September 27, 2019 12:00pm
Location: West Hall
Organized By: Life in Graduate School Seminars

Computational Resources at Michigan

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Workshop / Seminar Mon, 16 Sep 2019 09:21:06 -0400 2019-09-27T12:00:00-04:00 2019-09-27T13:00:00-04:00 West Hall Life in Graduate School Seminars Workshop / Seminar West Hall
HET Seminar | Extremal Correlators (September 27, 2019 3:00pm) https://events.umich.edu/event/67551 67551-16892236@events.umich.edu Event Begins: Friday, September 27, 2019 3:00pm
Location: West Hall
Organized By: Leinweber Center for Theoretical Physics

I will review some of the properties of extremal correlators. I will then describe the large charge limit of some N=2 theories in four dimensions. I will derive a dual random matrix description which admits a ’t Hooft expansion, which is dual to the double scaling limit of the gauge theory. I will compute the analytic and non-analytic terms in the ’t Hooft coupling and give some physical interpretation of the results.

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Lecture / Discussion Mon, 23 Sep 2019 13:31:06 -0400 2019-09-27T15:00:00-04:00 2019-09-27T16:00:00-04:00 West Hall Leinweber Center for Theoretical Physics Lecture / Discussion West Hall
“Mobilizing ‘Blackness’: From the Haitian Revolution to Now” (September 28, 2019 10:00am) https://events.umich.edu/event/66703 66703-16770291@events.umich.edu Event Begins: Saturday, September 28, 2019 10:00am
Location: West Hall
Organized By: Department of Afroamerican and African Studies

From Negritude, to the Anti-Apartheid movement, to Mizrahi Jewish claims to being Black Panthers, to Asian/African/Caribbean coalitions in the United Kingdom, to articulations by German and French youth today, this symposium will address the ways in which “Blackness” has been mobilized to make claims on state and other resources. It will engage the anti-normative forms of living Blackness has enabled. Given these histories and contemporary articulations, it asks: Who can claim Blackness? Under what conditions and with what effect can one make this claim? To what extent does claiming Blackness lead to social change? What are the conditions for coalition around claiming Blackness? Does racism persist, even amongst people of color, in spite of this coalitional claim?

The symposium is free and open to the public and will include a special screening of the documentary Whose Streets? (2018) and the short What Kind of Power Y’All Got (2016) with a Q&A with the filmmakers to follow in Lecture Hall II of the Modern Language Building on Friday, September 27 at 7 PM.

If you have any questions, please contact Damani Partridge (djpartri@umich.edu)

View the schedule online: myumi.ch/zxKNx

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Conference / Symposium Thu, 26 Sep 2019 11:02:40 -0400 2019-09-28T10:00:00-04:00 2019-09-28T13:00:00-04:00 West Hall Department of Afroamerican and African Studies Conference / Symposium Symposium Slider
HEP-Astro Seminar | Status of Belle II (September 30, 2019 4:00pm) https://events.umich.edu/event/66186 66186-16719559@events.umich.edu Event Begins: Monday, September 30, 2019 4:00pm
Location: West Hall
Organized By: Department of Physics

Belle II and SuperKEKB are the upgrades to the very successful Belle and KEKB B-factory. The goal of this new effort is to increase the data set by a factor of 50 enabling the search for physics beyond the standard model at the intensity frontier. Data taking started in early 2019, and I will describe the new detector and accelerator, give its present status, show some preliminary results, and estimate future prospects.

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Workshop / Seminar Mon, 30 Sep 2019 18:17:18 -0400 2019-09-30T16:00:00-04:00 2019-09-30T17:00:00-04:00 West Hall Department of Physics Workshop / Seminar West Hall
Physics & Astronomy Special Joint Colloquium | Sexual Harassment in STEM: A View from the National Academies (October 1, 2019 3:00pm) https://events.umich.edu/event/66763 66763-16776776@events.umich.edu Event Begins: Tuesday, October 1, 2019 3:00pm
Location: West Hall
Organized By: Department Colloquia

Persistent sexual harassment of women in science has remained a challenge for decades. It jeopardizes progress in closing the gender gap, damages research integrity, and results in a costly loss of talent. In 2016, the National Academies of Sciences, Engineering, and Medicine assembled a committee to conduct a study on this problem. The committee published a comprehensive report in 2018 titled, "Sexual Harassment of Women: Climate, Culture, and Consequences in Academic Sciences, Engineering, and Medicine." The report identifies key findings on the causes and consequences of sexual harassment, and lays out recommendations for institutional policies, strategies, and practices to address and prevent it. U-M Professors Lilia Cortina and Anna Kirkland were two members of that committee. In this talk they will review key findings from the report and discuss implications at the department level.

Please note: Should you require any accommodations to ensure equal access and opportunity related to this event please contact Stacy Tiburzi at 734-764-3440 or stibu@umich.edu.

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Workshop / Seminar Tue, 10 Sep 2019 10:07:37 -0400 2019-10-01T15:00:00-04:00 2019-10-01T16:00:00-04:00 West Hall Department Colloquia Workshop / Seminar West Hall
CM-AMO Seminar | Shedding New Light on Dirac Materials with Nonlinear Optics (October 1, 2019 4:00pm) https://events.umich.edu/event/67592 67592-16900780@events.umich.edu Event Begins: Tuesday, October 1, 2019 4:00pm
Location: West Hall
Organized By: Department of Physics

Nonlinear optics has recently emerged as an attractive approach for both probing topological properties and driving Dirac materials into new states. Here, I will describe our use of ultrafast nonlinear optics, especially at terahertz (THz) frequencies, to study three representative Dirac materials: graphene micro-ribbons, topological insulators, and Weyl semimetals. We used THz magneto-optical spectroscopy to examine periodic arrays of graphene micro-ribbons, enabling us to control the transmission and Faraday rotation spectra of THz pulses via coupling to discretized magnetoplasmon modes. In the Weyl semimetal TaAs, time-resolved second harmonic generation enabled us to reveal a new photoinduced phase, and THz emission spectroscopy was used to provide new insight into the circular photogalvanic effect. Finally, we used intense THz pulses to drive and coherently control structural dynamics in the topological insulator Bi2Se3. Overall, our studies demonstrate the utility of nonlinear optics in shedding new light on both static and dynamic properties of topological materials.

Biography: Dr. Rohit P. Prasankumar received a B.S. in Electrical Engineering from the University of Texas at Austin in 1997 and the M.S. and Ph.D. degrees in Electrical Engineering from MIT in 1999 and 2003, respectively. His thesis work, completed in 2003, concentrated on developing novel approaches for self-starting mode-locking in solid state lasers. Dr. Prasankumar subsequently performed his postdoctoral research at Los Alamos National Laboratory (LANL), focusing on ultrafast mid-to-far-infrared dynamics in semiconductor nanostructures and strongly correlated compounds. He has been a technical staff member at the Center for Integrated Nanotechnologies (CINT) at LANL since 2006, with research interests principally directed towards the measurement of dynamics in complex materials, such as multiferroics, semiconductor nanowires, and topological materials, with high temporal and spatial resolution over a broad spectral range. He is also a research associate professor at the University of New Mexico.

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Workshop / Seminar Tue, 01 Oct 2019 18:17:13 -0400 2019-10-01T16:00:00-04:00 2019-10-01T17:00:00-04:00 West Hall Department of Physics Workshop / Seminar West Hall
Department Colloquium | Towards a Better Understanding of the Electroweak Symmetry Breaking Mechanism (October 2, 2019 4:00pm) https://events.umich.edu/event/67174 67174-16805256@events.umich.edu Event Begins: Wednesday, October 2, 2019 4:00pm
Location: West Hall
Organized By: Undergrad Physics Events

In the Standard Model of particle physics, the massless Goldstone bosons resulting from spontaneous symmetry breaking of the Higgs field became longitudinal components of the W and Z bosons and thus make these vector bosons massive. It is critical to study longitudinal-longitudinal scattering of W and Z bosons at the LHC to validate this electroweak symmetry breaking mechanism and to search for other alternative mechanisms. I will present a few studies that are related to vector boson scattering using data collected by the ATLAS detector. In addition, I will discuss Phase-I and Phase-II upgrade activities of the ATLAS muon spectrometer that my research group has been involved in.

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Workshop / Seminar Fri, 27 Sep 2019 13:57:14 -0400 2019-10-02T16:00:00-04:00 2019-10-02T17:00:00-04:00 West Hall Undergrad Physics Events Workshop / Seminar West Hall
Department Colloquium | Towards a Better Understanding of the Electroweak Symmetry Breaking Mechanism (October 2, 2019 4:00pm) https://events.umich.edu/event/65281 65281-16565500@events.umich.edu Event Begins: Wednesday, October 2, 2019 4:00pm
Location: West Hall
Organized By: Department of Physics

In the Standard Model of particle physics, the massless Goldstone bosons resulting from spontaneous symmetry breaking of the Higgs field became longitudinal components of the W and Z bosons and thus make these vector bosons massive. It is critical to study longitudinal-longitudinal scattering of W and Z bosons at the LHC to validate this electroweak symmetry breaking mechanism and to search for other alternative mechanisms. I will present a few studies that are related to vector boson scattering using data collected by the ATLAS detector. In addition, I will discuss Phase-I and Phase-II upgrade activities of the ATLAS muon spectrometer that my research group has been involved in.

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Workshop / Seminar Wed, 02 Oct 2019 18:17:18 -0400 2019-10-02T16:00:00-04:00 2019-10-02T17:00:00-04:00 West Hall Department of Physics Workshop / Seminar West Hall
Statistics Department Seminar Series: Long Nguyen, Associate Professor, Department of Statistics, University of Michigan (October 4, 2019 10:00am) https://events.umich.edu/event/63883 63883-15977785@events.umich.edu Event Begins: Friday, October 4, 2019 10:00am
Location: West Hall
Organized By: Department of Statistics

We study posterior contraction behaviors for parameters of interest in the context of Bayesian mixture modeling, where the number of mixing components is unknown while the model itself may or may not be correctly specified. Posterior contraction rates are given under optimal transport distances for two popular types of prior specification: one requires explicitly a prior distribution on the number of mixture components, and a nonparametric Bayesian approach which places a prior on the space of mixing distributions. Paraphrasing George Box, all mixture models are misspecified, but some may be more interpretable than others — it will be shown that the modeling choice of kernel density functions plays perhaps the most impactful roles in determining the posterior contraction rates in the misspecified situations. Drawing on concrete parameter estimation rates I will highlight some aspects about the interesting tradeoffs between model expressiveness and interpretability that a statistical modeler must negotiate in the rich world of mixture modeling.
This work is joint with Aritra Guha and Nhat Ho.

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Workshop / Seminar Thu, 26 Sep 2019 14:21:24 -0400 2019-10-04T10:00:00-04:00 2019-10-04T11:00:00-04:00 West Hall Department of Statistics Workshop / Seminar Nguyen,Long
HEP-Astro Seminar | Exploring QCD with Jet Substructure at the LHC (October 7, 2019 4:00pm) https://events.umich.edu/event/67013 67013-16796440@events.umich.edu Event Begins: Monday, October 7, 2019 4:00pm
Location: West Hall
Organized By: Department of Physics

The inner structure of jets is sensitive to QCD across a wide range of scales, from the perturbative parton shower down to non-perturbative hadronization effects. This information has been used in many searches for distinguishing between different types of jets, but it has been challenging to produce theoretical predictions for these substructure observables due to the presence of non-global logarithms. Recent advances in jet grooming algorithms have made it possible to produce calculations beyond leading logarithmic accuracy for jet substructure observables for the first time at a hadron collider. I will discuss the measurement of the Soft Drop jet mass using data from the ATLAS experiment, which was the first measurement of a substructure observable which could be compared to theoretical predictions beyond leading logarithmic accuracy. I will then discuss the implications of this work, including the possibilities for Monte Carlo tuning as well as measurements of Standard Model parameters.

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Workshop / Seminar Mon, 07 Oct 2019 18:17:20 -0400 2019-10-07T16:00:00-04:00 2019-10-07T17:00:00-04:00 West Hall Department of Physics Workshop / Seminar West Hall
CM-AMO Seminar | Quantifying the Impact of State-Mixing on the Rydberg Excitation Blockade (October 8, 2019 4:00pm) https://events.umich.edu/event/67614 67614-16902922@events.umich.edu Event Begins: Tuesday, October 8, 2019 4:00pm
Location: West Hall
Organized By: Department of Physics

The Rydberg excitation blockade, a process in which interactions among highly-excited atoms suppress laser excitation, has been at the heart of an impressive array of recent achievements in quantum information and simulation. It has been shown that state-mixing interactions, which result from couplings among multi particle Rydberg states near Förster resonance, may compromise the effectiveness of the blockade under otherwise favorable conditions [1]. We present progress on an experiment in which we seek to quantify the negative impact of state-mixing on the blockade. We use state-selective field ionization spectroscopy to measure, on a shot-by-shot basis, the distribution of Rydberg states populated during narrowband laser excitation of ultracold rubidium atoms. Our method allows us to quantify both the “mixing-free” blockade effectiveness, as well as the number of additional Rydberg excitations added by each mixing event.

[1] A. Reinhard, et al, PRL, 100, 123007 (2008)

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Workshop / Seminar Tue, 08 Oct 2019 18:17:21 -0400 2019-10-08T16:00:00-04:00 2019-10-08T17:00:00-04:00 West Hall Department of Physics Workshop / Seminar West Hall
Department Colloquium | Engineering Correlation and Topology in Two-Dimensional Moire Superlattices (October 9, 2019 4:00pm) https://events.umich.edu/event/67175 67175-16805257@events.umich.edu Event Begins: Wednesday, October 9, 2019 4:00pm
Location: West Hall
Organized By: Undergrad Physics Events

Van der Waals heterostructures of atomically thin crystals offer an exciting new platform to design novel electronic and optical properties. In this talk, I will describe how to engineer correlated and topological physics using moire superlattice in two dimensional heterostructures. I will show that we can realize and control extremely rich condensed matter physics, ranging from correlated Mott insulator and superconductivity to ferromagnetism and topological Chern insulator, in a single device featuring the ABC trilayer graphene and boron nitride moire superlattices.

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Workshop / Seminar Fri, 27 Sep 2019 13:58:52 -0400 2019-10-09T16:00:00-04:00 2019-10-09T17:00:00-04:00 West Hall Undergrad Physics Events Workshop / Seminar West Hall
Department Colloquium | Engineering Correlation and Topology in Two-Dimensional Moire Superlattices (October 9, 2019 4:00pm) https://events.umich.edu/event/64804 64804-16446948@events.umich.edu Event Begins: Wednesday, October 9, 2019 4:00pm
Location: West Hall
Organized By: Department of Physics

Van der Waals heterostructures of atomically thin crystals offer an exciting new platform to design novel electronic and optical properties. In this talk, I will describe how to engineer correlated and topological physics using moire superlattice in two dimensional heterostructures. I will show that we can realize and control extremely rich condensed matter physics, ranging from correlated Mott insulator and superconductivity to ferromagnetism and topological Chern insulator, in a single device featuring the ABC trilayer graphene and boron nitride moire superlattices.

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Workshop / Seminar Wed, 09 Oct 2019 18:17:08 -0400 2019-10-09T16:00:00-04:00 2019-10-09T17:00:00-04:00 West Hall Department of Physics Workshop / Seminar West Hall
Statistics Department Seminar Series: Samory Kpotufe, Associate Professor, Department of Statistics, Columbia University (October 11, 2019 10:00am) https://events.umich.edu/event/63884 63884-15977786@events.umich.edu Event Begins: Friday, October 11, 2019 10:00am
Location: West Hall
Organized By: Department of Statistics

Abstract:
The problem of transfer and domain adaptation is ubiquitous in machine learning and concerns situations where predictive technologies, trained on a given source dataset, have to be transferred to a new target domain that is somewhat related. For example, transferring voice recognition trained on American English accents to apply to Scottish accents, with minimal retraining. A first challenge is to understand how to properly model the ‘distance’ between source and target domains, viewed as probability distributions over a feature space.

In this talk we will argue that various existing notions of distance between distributions turn out to be pessimistic, i.e., these distances might appear high in many situations where transfer is possible, even at fast rates. Instead we show that some new notions of distance tightly capture a continuum from easy to hard transfer, and furthermore can be adapted to, i.e., do not need to be estimated in order to perform near-optimal transfer. Finally we will discuss near-optimal approaches to minimizing sampling of target data (e.g. sampling Scottish speech), when one already has access to a given amount of source data (e.g. American speech).

This talk is based on some joint work with G. Martinet, and ongoing work with S. Hanneke.

Short-Bio:
Samory Kpotufe is Associate Professor in Statistics at Columbia University. He works in machine learning, with an emphasis on nonparametric methods and high dimensional statistics. Generally, his interests are in understanding basic learning scenarios under practical constraints from modern application domains. He has previously held positions at the Max Planck Institute in Germany, the Toyota Technological Institute at Chicago, and Princeton University.

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Workshop / Seminar Wed, 02 Oct 2019 14:33:27 -0400 2019-10-11T10:00:00-04:00 2019-10-11T11:00:00-04:00 West Hall Department of Statistics Workshop / Seminar Kpotufe,Samory
Department Colloquium | Quantum Tricks for Detecting Dark Matter Waves (October 16, 2019 4:00pm) https://events.umich.edu/event/65282 65282-16565501@events.umich.edu Event Begins: Wednesday, October 16, 2019 4:00pm
Location: West Hall
Organized By: Department of Physics

Low mass dark matter manifests as large amplitude classical bosonic waves which exert subtle forces on sensitive experimental apparatus. In conventional experiments, the tiny predicted signals are swamped by the zero-point noise of the quantum vacuum. In this talk, I will describe current research in surpassing the Standard Quantum Limit in readout noise by utilizing the toolboxes of quantum optics, atomic physics, and quantum computing. Topics include the QCD axion and the vanishing neutron electric dipole moment, quantum non-demolition measurements with superconducting qubits and other metamaterials, and stimulated emission with non-classical sensor preparation.

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Workshop / Seminar Wed, 16 Oct 2019 18:17:17 -0400 2019-10-16T16:00:00-04:00 2019-10-16T17:00:00-04:00 West Hall Department of Physics Workshop / Seminar West Hall
Department Colloquium | Quantum Tricks for Detecting Dark Matter Waves (October 16, 2019 4:00pm) https://events.umich.edu/event/67177 67177-16805258@events.umich.edu Event Begins: Wednesday, October 16, 2019 4:00pm
Location: West Hall
Organized By: Undergrad Physics Events

Low mass dark matter manifests as large amplitude classical bosonic waves which exert subtle forces on sensitive experimental apparatus. In conventional experiments, the tiny predicted signals are swamped by the zero-point noise of the quantum vacuum. In this talk, I will describe current research in surpassing the Standard Quantum Limit in readout noise by utilizing the toolboxes of quantum optics, atomic physics, and quantum computing. Topics include the QCD axion and the vanishing neutron electric dipole moment, quantum non-demolition measurements with superconducting qubits and other metamaterials, and stimulated emission with non-classical sensor preparation.

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Workshop / Seminar Fri, 27 Sep 2019 14:03:06 -0400 2019-10-16T16:00:00-04:00 2019-10-16T17:00:00-04:00 West Hall Undergrad Physics Events Workshop / Seminar West Hall
Statistics Department Seminar Series: Genevera Allen, Associate Professor of Electrical and Computer Engineering, Statistics and Computer Science, Rice University (October 18, 2019 10:00am) https://events.umich.edu/event/63885 63885-15977787@events.umich.edu Event Begins: Friday, October 18, 2019 10:00am
Location: West Hall
Organized By: Department of Statistics

Abstract:
Data integration, or the strategic analysis of multiple sources of data simultaneously, can often lead to discoveries that may be hidden in individual analyses of a single data source. In this talk, we present several new techniques for data integration of mixed, multi-view data where multiple sets of features, possibly each of a different domain, are measured for the same set of samples. This type of data is common in heathcare, biomedicine, national security, multi-senor recordings, multi-modal imaging, and online advertising, among others. In this talk, we specifically highlight how mixed graphical models and new feature selection techniques for mixed, mutli-view data allow us to explore relationships amongst features from different domains. Next, we present new frameworks for integrated principal components analysis and integrated generalized convex clustering that leverage diverse data sources to discover joint patterns amongst the samples. We apply these techniques to integrative genomic studies in cancer and neurodegenerative diseases to make scientific discoveries that would not be possible from analysis of a single data set.

Short-Bio:
Genevera Allen is an Associate Professor of Electrical and Computer Engineering, Statistics and Computer Science at Rice University and an investigator at the Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital and Baylor College of Medicine. She is also the Founder and Faculty Director of the Rice Center for Transforming Data to Knowledge, informally called the Rice D2K Lab. Dr. Allen's research focuses on developing statistical machine learning tools to help scientists make reproducible data-driven discoveries. Her work lies in the areas of interpretable machine learning, optimization, data integration, modern multivariate analysis, and graphical models with applications in neuroscience and bioinformatics. Dr. Allen is the recipient of several honors including a National Science Foundation Career award, the George R. Brown School of Engineering's Research and Teaching Excellence Award at Rice University, and in 2014, she was named to the "Forbes '30 under 30': Science and Healthcare" list. Dr. Allen received her PhD in statistics from Stanford University (2010), under the mentorship of Prof. Robert Tibshirani, and her bachelors, also in statistics, from Rice University (2006).

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Workshop / Seminar Thu, 10 Oct 2019 13:56:18 -0400 2019-10-18T10:00:00-04:00 2019-10-18T11:00:00-04:00 West Hall Department of Statistics Workshop / Seminar Allen
HET Seminar | "Quantum Superposition of Massive Bodies" (October 18, 2019 3:00pm) https://events.umich.edu/event/67321 67321-16837721@events.umich.edu Event Begins: Friday, October 18, 2019 3:00pm
Location: West Hall
Organized By: Leinweber Center for Theoretical Physics

We analyse a gedankenexperiment previously considered by Mari et al. that involves quantum superpositions of charged and/or massive bodies ("particles'') under the control of the observers, Alice and Bob. In the electromagnetic case, we show that the quantization of electromagnetic radiation (which causes decoherence of Alice's particle) and vacuum fluctuations of the electromagnetic field (which limits Bob's ability to localize his particle to better than a charge-radius) both are essential for avoiding apparent paradoxes with causality and complementarity. We then analyze the gravitational version of this gedankenexperiment. We show that the analysis of the gravitational case is in complete parallel with the electromagnetic case provided that gravitational radiation is quantized and that vacuum fluctuations limit the localization of a particle to no better than a Planck length. This provides support for the view that (linearized) gravity should have a quantum field description.

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Lecture / Discussion Tue, 24 Sep 2019 10:38:08 -0400 2019-10-18T15:00:00-04:00 2019-10-18T16:00:00-04:00 West Hall Leinweber Center for Theoretical Physics Lecture / Discussion West Hall
The Michigan Anthropology Colloquia Series: "Copts and Christian-Muslim Mediation: The Social Life of Theology in Egypt" (October 18, 2019 3:00pm) https://events.umich.edu/event/62987 62987-15528499@events.umich.edu Event Begins: Friday, October 18, 2019 3:00pm
Location: West Hall
Organized By: Department of Anthropology

"For Egypt's Coptic Orthodox, image theology is central to mediating human-divine relations. From the Arab uprisings to Sisi's military coup, varying theologies of material imagination have enabled communal critique and minoritarian identification. This talk navigates the social life of theology to understand how visual images organize relations between Christians and Muslims toward national and sectarian ends. In doing so, it considers the communicative aesthetics of religion and the creative making of religious difference within the terms of national unity."

The Michigan Anthropology Colloquia Series presents speakers on current topics in the field of anthropology

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Lecture / Discussion Tue, 08 Oct 2019 14:54:51 -0400 2019-10-18T15:00:00-04:00 2019-10-18T17:00:00-04:00 West Hall Department of Anthropology Lecture / Discussion West Hall
Complex Systems - Quant. Bio Seminar | Stochastic Turing patterns in oceans, brains and biofilms (October 21, 2019 12:00pm) https://events.umich.edu/event/68409 68409-17080044@events.umich.edu Event Begins: Monday, October 21, 2019 12:00pm
Location: West Hall
Organized By: The Center for the Study of Complex Systems

A special seminar co-hosted by Quantitative Bio. Seminars & CSCS. The first of two talks Professor Goldenfeld will be giving in two days at the University of Michigan

ABSTRACT
Why are the patterns of plankton in the ocean so patchy? Why do frequently described geometrical hallucinations tend to fall into one of four different classes of pattern? Why don't we see hallucinations all the time? And why do populations in ecosystems tend to have noisy cycles in abundance? This talk explains how these phenomena all arise from the discreteness of the underlying entities, be they the on-off states of neurons or the numbers of bacteria in a fluid volume of ocean, or the number of signaling molecules in a biofilm. I explain how tools from statistical mechanics can yield insights into these phenomena, and report on a range of studies that include the operation of the primate visual cortex, the behavior of signalling molecules in a forward-engineered synthetic biofilm, and the fluctuating patterns and populations of marine organisms.

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Workshop / Seminar Tue, 15 Oct 2019 15:45:09 -0400 2019-10-21T12:00:00-04:00 2019-10-21T13:00:00-04:00 West Hall The Center for the Study of Complex Systems Workshop / Seminar Swanlund Professor of Physics Nigel Goldenfeld
Quantitative Biology Seminar | Stochastic Turing Patterns in Oceans, Brains and Biofilms (October 21, 2019 12:00pm) https://events.umich.edu/event/68369 68369-17071276@events.umich.edu Event Begins: Monday, October 21, 2019 12:00pm
Location: West Hall
Organized By: Department of Physics

Why are the patterns of plankton in the ocean so patchy? Why do frequently described geometrical hallucinations tend to fall into one of four different classes of pattern? Why don't we see hallucinations all the time? And why do populations in ecosystems tend to have noisy cycles in abundance? This talk explains how these phenomena all arise from the discreteness of the underlying entities, be they the on-off states of neurons or the numbers of bacteria in a fluid volume of ocean, or the number of signaling molecules in a biofilm. I explain how tools from statistical mechanics can yield insights into these phenomena, and report on a range of studies that include the operation of the primate visual cortex, the behavior of signalling molecules in a forward-engineered synthetic biofilm, and the fluctuating patterns and populations of marine organisms.



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Workshop / Seminar Mon, 21 Oct 2019 18:17:04 -0400 2019-10-21T12:00:00-04:00 2019-10-21T13:00:00-04:00 West Hall Department of Physics Workshop / Seminar West Hall
Special CM-AMO Seminar | Inside Nature Physics (October 21, 2019 2:00pm) https://events.umich.edu/event/68304 68304-17045980@events.umich.edu Event Begins: Monday, October 21, 2019 2:00pm
Location: West Hall
Organized By: Department of Physics

Ever wondered what happens behind the scenes at Nature Research journals? We'll discuss what our editors look for in a paper, how we make our decisions, and some tips for writing papers and navigating the submission and review process. Hopefully there will also be plenty of time for questions and discussion.

Bio: David Abergel is an Associate Editor at Nature Physics. After completing a PhD in 2007, he did postdocs at the University of Manitoba and the University of Maryland, before taking a position at Nordita in Stockholm. His research was in condensed-matter theory, mainly focusing on 2D materials and topological materials. In 2017, he joined Nature Physics and is now a full-time editor.

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Workshop / Seminar Mon, 21 Oct 2019 18:17:04 -0400 2019-10-21T14:00:00-04:00 2019-10-21T15:00:00-04:00 West Hall Department of Physics Workshop / Seminar West Hall
HEP-Astro Seminar | Higgs Boson Decay as a Probe to the Unsolved Mysteries in the Universe: dark energy, dark matter and missing antimatter (October 21, 2019 4:00pm) https://events.umich.edu/event/64425 64425-16348357@events.umich.edu Event Begins: Monday, October 21, 2019 4:00pm
Location: West Hall
Organized By: Department of Physics

Despite being a remarkably simple theoretical model, the Higgs mechanism is the only known theory that is connected to some of the most profound mysteries in the modern physics: dark energy, dark matter and missing antimatter. Measurements of the Higgs boson decay may shield lights on those open questions. In this talk, I will present a few selective results from the ATLAS experiment on the Higgs boson decays. Namely the first observation of the Higgs boson decay to a pair of b-quarks, which had eluded us for many years despite it is the most probable Higgs decay channel; novel techniques to search for potential new physics using the hardonically decaying Higgs boson, and a first search for singly produced long-lived neutral particle that may be realized via Higgs portal. The talk will mainly focus on general descriptions of the measurements without too much technical details, so that the content is accessible to non experimental particle physicists.

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Workshop / Seminar Mon, 21 Oct 2019 18:17:03 -0400 2019-10-21T16:00:00-04:00 2019-10-21T17:00:00-04:00 West Hall Department of Physics Workshop / Seminar West Hall
Department Colloquium | Gravitational Waves and Neutron Rich Dense Matter (October 23, 2019 4:00pm) https://events.umich.edu/event/67178 67178-16805259@events.umich.edu Event Begins: Wednesday, October 23, 2019 4:00pm
Location: West Hall
Organized By: Undergrad Physics Events

In 2017 gravitational waves, oscillations of space-time, were detected from the collision of two neutron stars. This historic event provides new insight into very dense neutron rich matter. We compare these observations to the PREX II experiment. PREX uses parity violating electron scattering to precisely locate the 126 neutrons in 208Pb. Despite differing in size by 18 orders of magnitude, both the Pb nucleus and a neutron star are made of the same neutrons, with the same strong interactions, and have the same equation of state (pressure as a function of density). Therefore, PREX II has important implications for neutron star mergers and the structure of neutron stars.

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Workshop / Seminar Wed, 23 Oct 2019 12:47:34 -0400 2019-10-23T16:00:00-04:00 2019-10-23T17:00:00-04:00 West Hall Undergrad Physics Events Workshop / Seminar West Hall
Department Colloquium | Gravitational Waves, Very Dense Matter, and Laboratory Experiments (October 23, 2019 4:00pm) https://events.umich.edu/event/65283 65283-16565502@events.umich.edu Event Begins: Wednesday, October 23, 2019 4:00pm
Location: West Hall
Organized By: Department of Physics

In 2017 gravitational waves, oscillations of space-time, were detected from the collision of two neutron stars. This historic event provides new insight into very dense neutron rich matter. We compare these observations to the PREX II experiment. PREX uses parity violating electron scattering to precisely locate the 126 neutrons in 208Pb. Despite differing in size by 18 orders of magnitude, both the Pb nucleus and a neutron star are made of the same neutrons, with the same strong interactions, and have the same equation of state (pressure as a function of density). Therefore, PREX II has important implications for neutron star mergers and the structure of neutron stars.

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Workshop / Seminar Wed, 23 Oct 2019 18:17:02 -0400 2019-10-23T16:00:00-04:00 2019-10-23T17:00:00-04:00 West Hall Department of Physics Workshop / Seminar West Hall
Statistics Department Seminar Series: Jie Peng, Professor, Department of Statistics, UC Davis (October 25, 2019 10:00am) https://events.umich.edu/event/63886 63886-15977788@events.umich.edu Event Begins: Friday, October 25, 2019 10:00am
Location: West Hall
Organized By: Department of Statistics

Diffusion MRI is an in vivo and non invasive imaging technology that uses water diffusion as a proxy to probe architecture of biological tissues. Diffusion MRI technology has been widely used for white matter fiber tracts reconstruction. It also has many clinical applications in neurodegenerative diseases such as Alzheimer's.
In this talk, We discuss various statistical models for analyzing diffusion MRI data. These models aim to elucidate local (voxel-level) neuronal fiber organizations based on D-MRI measurements, which are in turn used as inputs in tracking algorithms to reconstruct white matter fiber tracts. We focus on their capability in resolving crossing fibers -- a major challenge in diffusion MRI data analysis, and their computational scalability. We also discuss spatial smoothing schemes that leverage information from neighboring brain voxels. These methods are applied to both synthetic experiments and to real D-MRI data from large imaging consortium.

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Workshop / Seminar Wed, 16 Oct 2019 15:19:27 -0400 2019-10-25T10:00:00-04:00 2019-10-25T11:00:00-04:00 West Hall Department of Statistics Workshop / Seminar Jie Peng
HET Seminar | Two-loop mixed EW-QCD corrections to Drell-Yan lepton pair production (October 25, 2019 3:00pm) https://events.umich.edu/event/68269 68269-17037493@events.umich.edu Event Begins: Friday, October 25, 2019 3:00pm
Location: West Hall
Organized By: Leinweber Center for Theoretical Physics

Drell-Yan lepton pair production is a key process for precision physics at the Large Hadron Collider. In this talk I will consider the two-loop amplitudes required for the full O(\alpha \alpha_s) corrections to this process and discuss the calculation of the required Feynman integrals. While algebraic linear combinations of the integrals fulfill $\;epsilon$ decoupled differential equations, the symbol letters are provably non-rationalizable. I will show that they can nevertheless be integrated in terms of conventional multiple polylogarithms with algebraic arguments, which allow for fast and stable numerical evaluations.

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Lecture / Discussion Thu, 10 Oct 2019 14:06:55 -0400 2019-10-25T15:00:00-04:00 2019-10-25T16:00:00-04:00 West Hall Leinweber Center for Theoretical Physics Lecture / Discussion West Hall
HEP-Astro Seminar | Lensing and Delensing: Results and Updates from BICEP/Keck and the South Pole Telescope (October 28, 2019 4:00pm) https://events.umich.edu/event/67014 67014-16796441@events.umich.edu Event Begins: Monday, October 28, 2019 4:00pm
Location: West Hall
Organized By: Department of Physics

Gravitational lensing of the cosmic microwave background (CMB) encodes information from the low-redshift universe. Therefore, its measurement is useful for constraining cosmological parameters that describe structure formation, e.g. Omega_m, sigma_8, and the sum of neutrino masses. In this talk, I will present a measurement of and the cosmological constraints from the CMB lensing potential and its power spectrum using data from the SPTpol 500 deg^2 survey. From the minimum variance combination of the lensing estimators from all combinations of SPTpol temperature and polarization data, we measure the lensing amplitude A_MV = 0.944 \pm 0.058 (Stat.) \pm 0.025 (Sys.), which constitutes the tightest lensing amplitude measurement using ground-based CMB data alone. Restricting to only polarization data, we measure the lensing amplitude A_Pol = 0.906 \pm 0.090 (Stat.) \pm 0.040 (Sys.), which is more constraining then our measurement using only temperature data. As SPT-3G, the successor to SPTpol, and other CMB experiments continue to lower the CMB map noise levels, polarization data will dominate the signal-to-noise of lensing measurements for angular multipoles below at least several hundred. Looking to the future, high signal-to-noise measurements of lensing enabled by deep polarization maps is crucial for constraining the sum of neutrino masses and the amplitude of inflationary gravitational waves through delensing. If time permits, I will give an update on the current effort of delensing the BICEP/Keck telescope data.

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Workshop / Seminar Mon, 28 Oct 2019 18:16:53 -0400 2019-10-28T16:00:00-04:00 2019-10-28T17:00:00-04:00 West Hall Department of Physics Workshop / Seminar West Hall
CM-AMO Seminar | Many-body Physics of Ultracold Gases in Synthetic Dimensions: from Self-trapping to Quantum Strings (October 29, 2019 4:00pm) https://events.umich.edu/event/68736 68736-17147124@events.umich.edu Event Begins: Tuesday, October 29, 2019 4:00pm
Location: West Hall
Organized By: Department of Physics

Synthetic dimensions alter one of the most fundamental properties in nature, the dimension of space. They allow, for example, a low-dimensional system to act as effectively higher-dimensional. Experiments on ultracold systems create synthetic dimensions using internal or external degrees of freedom of particles for highly controllable quantum simulation.

We consider two methods to create synthetic dimensions in ultracold gases - momentum states of ultracold atoms, and rotational states of ultracold dipolar molecules. In the atomic system with the momentum-state lattice, which has been realized experimentally in the Gadway group, pairs of Raman lasers drive momentum-state transitions, realizing tunnelings in the synthetic lattice. In the molecular system, microwaves can be used to induce rotational-state transitions, realizing tunnelings in the synthetic lattice which can span hundreds of sites. Both systems can show many-body physics due to strong interactions arising respectively from contact interactions and dipolar interactions. We discuss the many-body physics of these systems, ranging from momentum-dependent self-trapping that has been experimentally observed in the atomic systems, to a novel string phase that is theoretically predicted to occur in the molecular systems.

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Workshop / Seminar Tue, 29 Oct 2019 18:16:50 -0400 2019-10-29T16:00:00-04:00 2019-10-29T17:00:00-04:00 West Hall Department of Physics Workshop / Seminar West Hall
Statistics Department Seminar Series: Heping Zhang, Susan Dwight Bliss Professor of Biostatistics, Professor in the Child Study Center and Professor of Statistics and Data Science, Yale University (November 1, 2019 10:00am) https://events.umich.edu/event/63887 63887-15977789@events.umich.edu Event Begins: Friday, November 1, 2019 10:00am
Location: West Hall
Organized By: Department of Statistics

Ordinal outcomes are common in scientific research and everyday practice, and we often rely on regression models to make inference. A long-standing problem with such regression analyses is the lack of effective diagnostic tools for validating model assumptions. The difficulty arises from the fact that an ordinal variable has discrete values that are labeled with, but not, numerical values. The values merely represent ordered categories. In this paper, we propose a surrogate approach to defining residuals for an ordinal outcome Y. The idea is to define a continuous variable S as a ``surrogate'' of Y and then obtain residuals based on S. For the general class of cumulative link regression models, we study the residual's theoretical and graphical properties. We show that the residual has null properties similar to those of the common residuals for continuous outcomes. Our numerical studies demonstrate that the residual has power to detect misspecification with respect to 1) mean structures; 2) link functions; 3) heteroscedasticity; 4) proportionality; and 5) mixed populations. The proposed residual also enables us to develop numeric measures for goodness-of-fit using classical distance notions. Our results suggest that compared to a previously defined residual, our residual can reveal deeper insights into model diagnostics. We stress that this work focuses on residual analysis, rather than hypothesis testing. The latter has limited utility as it only provides a single p-value, whereas our residual can reveal what components of the model are misspecified and advise how to make improvements.

This is a joint work with Dungang Liu, University of Cincinnati Lindner College of Business.

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Workshop / Seminar Wed, 23 Oct 2019 12:43:56 -0400 2019-11-01T10:00:00-04:00 2019-11-01T11:00:00-04:00 West Hall Department of Statistics Workshop / Seminar Heping Zhang
HET Seminar | Constraining higher-order gravities with subregion duality (November 1, 2019 3:00pm) https://events.umich.edu/event/68796 68796-17153399@events.umich.edu Event Begins: Friday, November 1, 2019 3:00pm
Location: West Hall
Organized By: Leinweber Center for Theoretical Physics

In higher derivative theories, gravity can propagate faster or slower than light. This fact has consequences for holographic constructs in AdS/CFT. In this talk, I will focus on the causal and entanglement wedges. I will argue that, in higher derivative theories, these wedges should be constructed using the fastest mode instead of null rays. I will show that using this proposal, the property of causal wedge inclusion, i.e. the fact that the causal wedge must be contained in the entanglement wedge, leads to more stringent constraints on the couplings than those imposed by hyperbolicity and boundary causality. I will elaborate on the implications of these results.

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Lecture / Discussion Thu, 24 Oct 2019 09:03:06 -0400 2019-11-01T15:00:00-04:00 2019-11-01T16:00:00-04:00 West Hall Leinweber Center for Theoretical Physics Lecture / Discussion West Hall
The Michigan Anthropology Colloquia Series: "Dating Iroquoia: Refined time frames for coalescence, conflict, and early European influences in northeastern North America" (November 1, 2019 3:00pm) https://events.umich.edu/event/63229 63229-15595501@events.umich.edu Event Begins: Friday, November 1, 2019 3:00pm
Location: West Hall
Organized By: Department of Anthropology

"Chronologies fundamentally underpin all other aspects of archaeological thought. When our timeframes shift, so to do the chains of inference that underpin our models and narratives. This talk will detail the results to date of the Dating Iroquoia project. It will review some of the most significant implications of our revised radiocarbon chronology for understanding processes of Iroquoian cultural development, including the timing of coalescence and conflict, the onset of historical enmity between the Huron-Wendat and Haudenosaunee, and the processes through which European goods were transmitted, received, or rejected by Iroquoian communities in Ontario and New York State. The results of this project demonstrate not only the utility of AMS dating and Bayesian chronological modelling for overcoming plateaus and reversals in the calibration curve but also for centering Indigenous agency in historical narratives and helping descendants to better understand the life and times of their ancestors."

The Michigan Anthropology Colloquia Series presents speakers on current topics in the field of anthropology

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Lecture / Discussion Mon, 07 Oct 2019 15:35:26 -0400 2019-11-01T15:00:00-04:00 2019-11-01T17:00:00-04:00 West Hall Department of Anthropology Lecture / Discussion West Hall
HEP-Astro Seminar | Exoplanet Systems as Laboratories for Planet Formation (November 4, 2019 4:00pm) https://events.umich.edu/event/64646 64646-16404982@events.umich.edu Event Begins: Monday, November 4, 2019 4:00pm
Location: West Hall
Organized By: Department of Physics

With knowledge of thousands of exoplanet systems from the NASA Kepler Mission, we are closer than ever to understanding how planets form. Patterns in exoplanet populations, compositions, and planetary system architectures are already revealing the most common outcomes of planet formation. I will discuss how I use exoplanet systems as laboratories to test theories of planet formation. My work ranges from characterizing broad patterns across many planetary systems to studying individual systems through their transits, transit timing variations, and radial velocities. In the next ten years, we will measure exoplanet multiplicities, orbital periods, masses, radii, eccentricities, inclinations, obliquities, dynamical interactions, atmospheric compositions, and host star properties using a combination of ground-based and space telescopes. These detailed observations of our exoplanet laboratories will allow us to place the solar system in its galactic context.

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Workshop / Seminar Mon, 04 Nov 2019 18:16:25 -0500 2019-11-04T16:00:00-05:00 2019-11-04T17:00:00-05:00 West Hall Department of Physics Workshop / Seminar West Hall
CM/AMO Seminar | X-ray Vision of Spins, Charges and Orbitals for Understanding Emergent electronic States in Complex Oxides (November 5, 2019 4:00pm) https://events.umich.edu/event/65481 65481-16605627@events.umich.edu Event Begins: Tuesday, November 5, 2019 4:00pm
Location: West Hall
Organized By: Department of Physics

Many of the most remarkable properties of quantum materials come from the interplay of multiple charge, orbital and spin degrees of freedom. Probing all of these with a single technique is consequently highly desirable. In this talk, I will describe how resonant inelastic x-ray scattering (RIXS) opens up important new possibilities for measuring these degrees of freedom. This includes observing precursor charge density wave correlations in cuprates [1], observing orbital hybridization in iridates [2], and characterizing the spin behavior within the transient state of photo-doped Sr_2IrO_4 [3].

References
1. H. Miao et al., Proc. Natl. Acad. Sci. U.S.A 114, 12430–12435 (2017); H. Miao et al., Phys. Rev. X 8, 011008 (2018); H. Miao et al., Phys. Rev. X 9, 031042 (2019)
2.Y. Wang et al., Phys. Rev. Lett. 122, 106401 (2019)
3. M. P. M. Dean et al., Nature Materials 15, 601-605 (2016); Y. Cao et al., Phil. Trans. R. Soc. A 377: 20170480 (2019)

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Workshop / Seminar Tue, 05 Nov 2019 18:16:20 -0500 2019-11-05T16:00:00-05:00 2019-11-05T17:00:00-05:00 West Hall Department of Physics Workshop / Seminar West Hall
Department Colloquium | Physics Adventures in Cancer Research: Cell Motility, Signaling, and Metastasis (November 6, 2019 4:00pm) https://events.umich.edu/event/67015 67015-16796442@events.umich.edu Event Begins: Wednesday, November 6, 2019 4:00pm
Location: West Hall
Organized By: Department of Physics

Struck by the near total absence of physics thinking and methods in biological research, for the last 30 years, the speaker has endeavored to understand certain phenomena utilizing methods that are based on Physics and are applied to the interpretation of complex biological data. She will discuss 3 examples. In conclusion, we will discuss: Are we ready for the Physics laws of Biology?

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Workshop / Seminar Wed, 06 Nov 2019 18:16:15 -0500 2019-11-06T16:00:00-05:00 2019-11-06T17:00:00-05:00 West Hall Department of Physics Workshop / Seminar West Hall
Department Colloquium | Physics Adventures in Cancer Research: Cell Motility, Signaling, and Metastasis (November 6, 2019 4:00pm) https://events.umich.edu/event/67179 67179-16805260@events.umich.edu Event Begins: Wednesday, November 6, 2019 4:00pm
Location: West Hall
Organized By: Undergrad Physics Events

Struck by the near total absence of physics thinking and methods in biological research, for the last 30 years, the speaker has endeavored to understand certain phenomena utilizing methods that are based on Physics and are applied to the interpretation of complex biological data. She will discuss 3 examples. In conclusion, we will discuss: Are we ready for the Physics laws of Biology?

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Workshop / Seminar Wed, 06 Nov 2019 11:37:37 -0500 2019-11-06T16:00:00-05:00 2019-11-06T17:00:00-05:00 West Hall Undergrad Physics Events Workshop / Seminar West Hall
CM Theory Seminar | Cyclotron Resonance Spectroscopy of Symmetry Broken States in Monolayer Graphene (November 7, 2019 4:00pm) https://events.umich.edu/event/65284 65284-16565503@events.umich.edu Event Begins: Thursday, November 7, 2019 4:00pm
Location: West Hall
Organized By: Department of Physics

Cyclotron resonance—the resonant absorption of light by charge carriers in a strong magnetic field—is widely used to measure the effective band mass of (semi-)conducting materials. This works because the CR absorption in systems having a parabolic dispersion—a reasonable description of most materials—is unaffected by inter-particle interactions. An intriguing corollary is that, for instance, in high mobility GaAs heterostructures when the electronic transport shows remarkably complex behavior in the fractional quantum Hall regime, there is still only a single cyclotron resonance peak that is qualitatively little different from a low-mobility device. But: in materials with a linear dispersion such as graphene, this proscription on spectroscopy of interactions does not hold. We have built a dedicated infrared magnetospectroscopy setup for exploring the cyclotron resonance of interacting Dirac systems, and will report progress including an exciting observation of full integer symmetry breaking of the underlying Landau levels in monolayer graphene. We will also discuss plans for `shining light’ on other correlated electron systems.

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Workshop / Seminar Thu, 07 Nov 2019 18:16:20 -0500 2019-11-07T16:00:00-05:00 2019-11-07T17:00:00-05:00 West Hall Department of Physics Workshop / Seminar West Hall
ROOM CHANGE: Statistics Department Seminar Series: Matthew Stephens, Professor, Departments of Statistics and Human Genetics, University of Chicago (November 8, 2019 10:00am) https://events.umich.edu/event/63888 63888-15977790@events.umich.edu Event Begins: Friday, November 8, 2019 10:00am
Location: West Hall
Organized By: Department of Statistics

Ever since the pioneering work of James and Stein, the normal means model has been the canonical model for illustrating the ideas and benefits of shrinkage estimation, and has been the subject of considerable theoretical study. By comparison, practical applications of the normal means model are relatively rare, and it has generally been overshadowed by methods like L1-regularization as a way of inducing sparsity. Here we argue that this should change: we describe some recently-developed Empirical Bayes ways to solve the normal means model, and describe how they can be applied to induce shrinkage, sparsity and smoothness in a range of practical applications, including False Discovery Rates, non-parametric regression, sparse regression, and sparse principal components analysis or factor analysis.

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Workshop / Seminar Mon, 04 Nov 2019 09:59:05 -0500 2019-11-08T10:00:00-05:00 2019-11-08T11:00:00-05:00 West Hall Department of Statistics Workshop / Seminar Matthew Stephens
Life After Graduate School Seminar | Still a Physicist, But Not How I Originally Expected (November 8, 2019 12:00pm) https://events.umich.edu/event/69026 69026-17215883@events.umich.edu Event Begins: Friday, November 8, 2019 12:00pm
Location: West Hall
Organized By: Department of Physics

From experimental HEP, to particle accelerator operations, PET isotope production, and proton beam therapy for treating cancer, my career has differed from what I envisioned years ago. I will share my experience as an example of what one can do with a physics degree after grad school. There is more “out there” than you may think. Questions and discussion will be encouraged.

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Workshop / Seminar Fri, 08 Nov 2019 18:16:44 -0500 2019-11-08T12:00:00-05:00 2019-11-08T13:00:00-05:00 West Hall Department of Physics Workshop / Seminar West Hall
HET Seminars | EDMs and CP-odd nucleon forces (November 8, 2019 3:00pm) https://events.umich.edu/event/68939 68939-17197041@events.umich.edu Event Begins: Friday, November 8, 2019 3:00pm
Location: West Hall
Organized By: Leinweber Center for Theoretical Physics

I will describe two recent papers [in the last stages of preparation]:
1. Paramagnetic EDMs (usually interpreted as electron electric dipole moment)
have seen a lot of experimental progress in the last decade. I evaluate the sensitivity
of electron EDM experiments to hadronic CP-violation, finding an independent limit on
e.g. theta-term at the level of 10^(-8). 2. In the second part of my talk I revisit the question
of CP-odd axion-nucleon vertices, relevant for the searches of the axionic 5th force.

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Lecture / Discussion Tue, 29 Oct 2019 13:59:40 -0400 2019-11-08T15:00:00-05:00 2019-11-08T16:00:00-05:00 West Hall Leinweber Center for Theoretical Physics Lecture / Discussion West Hall
The Michigan Anthropology Colloquia Series: "New face to an old name: Recent fossil discoveries from Woranso-Mille, Afar region, Ethiopia" (November 8, 2019 3:00pm) https://events.umich.edu/event/68429 68429-17080062@events.umich.edu Event Begins: Friday, November 8, 2019 3:00pm
Location: West Hall
Organized By: Department of Anthropology

"Woranso-Mille, a paleoanthropological site located in the Afar region of Ethiopia, has become one of the most important sites to understand the evolutionary history of early hominins during the mid-Pliocene. The geological sequence at this site (~150 meter-thick) samples almost one and a half million years, between >4.3 and <3.0 million years ago (Ma). It is the only site thus far that has provided incontrovertible fossil evidence showing that there were multiple related hominin species co-existing in close geographic proximity during the mid-Pliocene (3.5 – 3.3 Ma). Recently, a 3.8-million-year-old almost complete hominin cranium was discovered at the site and it was assigned to A. anamensis - the earliest known species of the genus Australopithecus – dated to 4.2 – 3.9 Ma. In addition to revealing the face of A. anamensis for the first time, the new cranium also challenged the long-held hypothesis of anagenetic transition from A. anamensis to Lucy’s species, A. afarensis, and added about 100kyr to the younger end of A. anamensis."

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Lecture / Discussion Fri, 01 Nov 2019 12:45:00 -0400 2019-11-08T15:00:00-05:00 2019-11-08T17:00:00-05:00 West Hall Department of Anthropology Lecture / Discussion West Hall
Quantitative Biology Seminar | Experimental Design for Large Scale Virtual Screening (November 11, 2019 12:00pm) https://events.umich.edu/event/68968 68968-17205309@events.umich.edu Event Begins: Monday, November 11, 2019 12:00pm
Location: West Hall
Organized By: Department of Physics

Virtual screening of commercial make-on-demand chemical libraries is a promising strategy for rapid, low-cost drug discovery. However, due to the uncertain predictive accuracy, it is not clear how to best integrate docking into discovery campaigns, an instance of a general problem for applying complex prediction methods. To address this challenge, I will describe how we designed a Bayesian optimal experiment to estimate the hit-rate as a function of predicted free energy of binding by carefully selecting ~500 compounds test in an in vitro binding assay. Using this an example, I will then describe a novel statistical and computational framework for efficiently computing Bayesian optimal designs. The core idea is to use stochastic gradient descent to simultaneously optimize the parameters of variational bounds of the expected information gain and the experimental degrees of freedom. Through implementing this in Pyro a probabilistic programming language built on PyTorch, this method can scale to designing highly informative experiments to calibrate a wide range of predictive models.

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Workshop / Seminar Mon, 11 Nov 2019 18:16:33 -0500 2019-11-11T12:00:00-05:00 2019-11-11T13:00:00-05:00 West Hall Department of Physics Workshop / Seminar West Hall
HEP-Astro Seminar | Searching for Long-lived Particles with Displaced Vertices in ATLAS (November 11, 2019 4:00pm) https://events.umich.edu/event/67016 67016-16796443@events.umich.edu Event Begins: Monday, November 11, 2019 4:00pm
Location: West Hall
Organized By: Department of Physics

Most searches for new physics at the Large Hadron Collider assume that a new particle produced in pp-collisions decays almost immediately, or is non-interacting and escapes the detector. However, a variety of new physics models that predict particles which decay inside the detector at a discernible distance from the interaction point. Such long-lived particles would create spectacular signatures and evade many prompt searches. In this talk I will focus on a search for long-lived particles in events with a displaced vertex and a muon. I will also discuss challenges for the Muon Spectrometer in the face of increasing LHC luminosity.

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Workshop / Seminar Mon, 11 Nov 2019 18:16:33 -0500 2019-11-11T16:00:00-05:00 2019-11-11T17:00:00-05:00 West Hall Department of Physics Workshop / Seminar West Hall
CM-AMO Seminar | Playing with a Quantum Toy: Exploring Thermalization Near Integrability with a Magnetic Quantum Newton's Cradle (November 12, 2019 4:00pm) https://events.umich.edu/event/69176 69176-17261053@events.umich.edu Event Begins: Tuesday, November 12, 2019 4:00pm
Location: West Hall
Organized By: Department of Physics

Thermalization of near-integrable quantum systems is an unresolved question. We will present a new experiment that explores the emergence of thermalization in a quantum system by studying the dynamics of the momentum in a dipolar quantum Newton's cradle consisting of highly magnetic dysprosium atoms. This system constitutes the first dipolar strongly interacting 1D Bose gas. These interactions provide tunability of both the strength of the integrability-breaking perturbation and the nature of the near-integrable dynamics. The work sheds light on the mechanisms by which isolated quantum many-body systems thermalize and on the temporal structure of the onset of thermalization. We anticipate our novel 1D dipolar gas will yield insights into quantum thermalization and strongly interacting quantum gases with long-range interactions.

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Workshop / Seminar Tue, 12 Nov 2019 18:16:41 -0500 2019-11-12T16:00:00-05:00 2019-11-12T17:00:00-05:00 West Hall Department of Physics Workshop / Seminar West Hall
Department Colloquium | KOTO: The Search for the Elusive K_L → πνν (November 13, 2019 4:00pm) https://events.umich.edu/event/69170 69170-17259020@events.umich.edu Event Begins: Wednesday, November 13, 2019 4:00pm
Location: West Hall
Organized By: Undergrad Physics Events

The KOTO experiment at J-PARC aims to help explain why we live in a matter dominant universe. It is believed that Charge-Parity (CP) violation is critical in this asymmetry, and studying where new CP violation can enter beyond the predictions of the Standard Model (SM) is an exciting frontier for discovering new physics.

The KOTO experiment was designed to observe and study the 𝐾_L → 𝜋𝜈𝜈 decay. The Standard Model (SM) prediction for the mode is 3.0 x 10^{-11} with a small theoretical uncertainty [1]. A previous experimental upper limit of 2.6 x 10^{-8} was set by the KEK E391a collaboration [2]. The rare “golden” decay is ideal for probing for physics beyond the standard model. A comparison of experimentally obtained results with SM calculations permits a test of the quark flavor region and provides a means to search for new physics.

The signature of the decay is a pair of photons from the π^0 decay and no other detected particles. For the measurement of the energies and positions of the photons, KOTO uses a Cesium Iodide (CSI) electromagnetic calorimeter as the main detector, and hermetic veto counters to guarantee that there are no other detected particles.

KOTO’s initial data was collected in 2013 and achieved a similar sensitivity as E391a result [3]. Since then, we completed hardware upgrades and had additional physics runs in 2015, 2016- 2018, and earlier this year. This presentation will present the motivation for this study, new results from KOTO [4], and discuss the status of the ongoing search in detecting 𝐾_L → 𝜋𝜈𝜈.

[1] C. Bobeth, A. J. Buras, A. Celis, and M. Jung, J. High Energy Phys. 04, 079 (2017). [2] J. K. Ahn et al., Phys. Rev. D 81, 072004 (2010).
[3] J. K. Ahn et al., Prog. Theor. Phys. 021C01 (2017).
[4] J. K. Ahn et al., Phys. Rev. Lett. 122 no.2, 021802 (2019

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Workshop / Seminar Wed, 06 Nov 2019 11:35:46 -0500 2019-11-13T16:00:00-05:00 2019-11-13T17:00:00-05:00 West Hall Undergrad Physics Events Workshop / Seminar West Hall
Department Colloquium | The Search for the Elusive K_L → πνν with the KOTO Detector (November 13, 2019 4:00pm) https://events.umich.edu/event/69073 69073-17224170@events.umich.edu Event Begins: Wednesday, November 13, 2019 4:00pm
Location: West Hall
Organized By: Department of Physics

The KOTO experiment at J-PARC aims to help explain why we live in a matter dominant universe. It is believed that Charge-Parity (CP) violation is critical in this asymmetry, and studying where new CP violation can enter beyond the predictions of the Standard Model (SM) is an exciting frontier for discovering new physics.

The KOTO experiment was designed to observe and study the 𝐾_L → 𝜋𝜈𝜈 decay. The Standard Model (SM) prediction for the mode is 3.0 x 10^{-11} with a small theoretical uncertainty [1]. A previous experimental upper limit of 2.6 x 10^{-8} was set by the KEK E391a collaboration [2]. The rare “golden” decay is ideal for probing for physics beyond the standard model. A comparison of experimentally obtained results with SM calculations permits a test of the quark flavor region and provides a means to search for new physics.

The signature of the decay is a pair of photons from the π^0 decay and no other detected particles. For the measurement of the energies and positions of the photons, KOTO uses a Cesium Iodide (CSI) electromagnetic calorimeter as the main detector, and hermetic veto counters to guarantee that there are no other detected particles.

KOTO's initial data was collected in 2013 and achieved a similar sensitivity as E391a result [3]. Since then, we completed hardware upgrades and had additional physics runs in 2015, 2016- 2018, and earlier this year. This presentation will present the motivation for this study, new results from KOTO [4], and discuss the status of the ongoing search in detecting 𝐾_L → 𝜋𝜈𝜈.

[1] C. Bobeth, A. J. Buras, A. Celis, and M. Jung, J. High Energy Phys. 04, 079 (2017). [2] J. K. Ahn et al., Phys. Rev. D 81, 072004 (2010).
[3] J. K. Ahn et al., Prog. Theor. Phys. 021C01 (2017).
[4] J. K. Ahn et al., Phys. Rev. Lett. 122 no.2, 021802 (2019

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Workshop / Seminar Wed, 13 Nov 2019 18:16:40 -0500 2019-11-13T16:00:00-05:00 2019-11-13T17:00:00-05:00 West Hall Department of Physics Workshop / Seminar West Hall
Statistics Department Seminar Series: Ben Hansen, Associate Professor, Department of Statistics, University of Michigan (November 15, 2019 10:00am) https://events.umich.edu/event/63889 63889-15977791@events.umich.edu Event Begins: Friday, November 15, 2019 10:00am
Location: West Hall
Organized By: Department of Statistics

To estimate intervention effects without the benefit of random assignment, an often useful beginning is to pair intervention group members to ostensibly similar counterparts receiving a control condition. In practice exact matches are rare, particularly if there are many measured covariates. Instead, matches may be made within calipers (Althauser & Rubin, 1970) of a unidimensional index. Modern indices arise by modeling specific aspects of the data. The most widely used matching indices are propensity scores (Rosenbaum & Rubin, 1983), followed by risk or prognostic scores (Miettinen, 1976; Hansen, 2008).

Adjudicating how close is close enough for matching is the murkiest aspect of the undertaking. Heuristics in wide use today pre-date the use of model-based matching indices, fail to adapt to the size of the model and sample, and lack theoretical support. In some cases these heuristics allow pairings of demonstrably dissimilar subjects; in others they declare wide swaths of the sample to be unmatchable, needlessly wasting data.

This talk presents a new way to determine calipers. Compatible with common index model specifications, its widths diminish as n increases, toward an asymptote of 0. If the index model is consistently estimated, then matched contrast-based impact estimates will be consistent as well, provided matches are made within these diminishing calipers. This result assumes no hidden bias, an untestable condition, alongside of additional conditions that can be enforced. In particular, it restricts growth of the index parameter's dimension relative to n, to a rate intermediate to those required for ordinary M-estimates to be consistent or root-n consistent (He & Shao, 2000).

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Workshop / Seminar Fri, 08 Nov 2019 14:37:06 -0500 2019-11-15T10:00:00-05:00 2019-11-15T11:00:00-05:00 West Hall Department of Statistics Workshop / Seminar Hansen,Ben
Life After Graduate School Seminar | Double Feature (November 15, 2019 12:00pm) https://events.umich.edu/event/69153 69153-17254948@events.umich.edu Event Begins: Friday, November 15, 2019 12:00pm
Location: West Hall
Organized By: Department of Physics

Life After Grad School Seminar

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Workshop / Seminar Fri, 15 Nov 2019 18:16:35 -0500 2019-11-15T12:00:00-05:00 2019-11-15T13:00:00-05:00 West Hall Department of Physics Workshop / Seminar West Hall
HET Seminars | “A Canonical Purification for the Entanglement Wedge Cross-Section” (November 15, 2019 2:00pm) https://events.umich.edu/event/69282 69282-17293660@events.umich.edu Event Begins: Friday, November 15, 2019 2:00pm
Location: West Hall
Organized By: Leinweber Center for Theoretical Physics

I will discuss a new entry in the AdS/CFT dictionary relating a geometric quantity called the entanglement wedge cross-section to the entropy of a canonical purification. I will also speculate about a connection to the split property in QFT.

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Lecture / Discussion Thu, 14 Nov 2019 10:17:43 -0500 2019-11-15T14:00:00-05:00 2019-11-15T15:00:00-05:00 West Hall Leinweber Center for Theoretical Physics Lecture / Discussion West Hall
HEP-Astro Seminar | Forward Modelling the Universe: Application to Cosmic Shear (November 18, 2019 4:00pm) https://events.umich.edu/event/67017 67017-16796444@events.umich.edu Event Begins: Monday, November 18, 2019 4:00pm
Location: West Hall
Organized By: Department of Physics

Observational cosmology is going through a golden age. In particular, we are in the midst of an influx of data from on-going experiments, such as the Dark Energy Survey (DES). In the coming five years, the volume and quality of data will rapidly increase as Stage IV surveys, Euclid, LSST and WFIRST, come online. Processing this data will require new algorithms and methods to maximise our science reach and to control for systematic errors. In this talk, I will present a method that we have developed called Monte-Carlo-Control-Loops that relies heavily on forward modelling the observed data by simulating all the processes from cosmology theory to images. Given the complexities of the late-time Universe, these forward models need to capture the important properties of galaxy populations and key features imprinted on the data from the experiments themselves. By bringing together all these elements with advanced statistical methods and new machine learning algorithms, we can build a process for extracting maximal information from the new data, which will allow us to extensively test the physics of the dark sector.

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Workshop / Seminar Mon, 18 Nov 2019 18:16:20 -0500 2019-11-18T16:00:00-05:00 2019-11-18T17:00:00-05:00 West Hall Department of Physics Workshop / Seminar West Hall
Department Colloquium | The Joys and Challenges in Changing to the Scale Up Paradigm (November 20, 2019 4:00pm) https://events.umich.edu/event/65285 65285-16565504@events.umich.edu Event Begins: Wednesday, November 20, 2019 4:00pm
Location: West Hall
Organized By: Department of Physics

Even before Purdue opened its Active Learning Center, I staked my claim to a room designed according to the SCALE UP model. Having stuck out my neck, I then had to jump in with both feet. I will share my experience in converting the introductory mechanics course– one of the major gateways required of all first-year engineering majors.

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Workshop / Seminar Wed, 20 Nov 2019 18:16:33 -0500 2019-11-20T16:00:00-05:00 2019-11-20T17:00:00-05:00 West Hall Department of Physics Workshop / Seminar West Hall
Department Colloquium | The Joys and Challenges in Changing to the Scale Up Paradigm (November 20, 2019 4:00pm) https://events.umich.edu/event/69172 69172-17259021@events.umich.edu Event Begins: Wednesday, November 20, 2019 4:00pm
Location: West Hall
Organized By: Undergrad Physics Events

Even before Purdue opened its Active Learning Center, I staked my claim to a room designed according to the SCALE UP model. Having stuck out my neck, I then had to jump in with both feet. I will share my experience in converting the introductory mechanics course– one of the major gateways required of all first-year engineering majors.

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Workshop / Seminar Wed, 06 Nov 2019 11:39:29 -0500 2019-11-20T16:00:00-05:00 2019-11-20T17:00:00-05:00 West Hall Undergrad Physics Events Workshop / Seminar West Hall
Statistics Department Seminar Series: Sebastien Roch, Professor, Department of Mathematics, University of Wisconsin-Madison (November 22, 2019 10:00am) https://events.umich.edu/event/63890 63890-15977792@events.umich.edu Event Begins: Friday, November 22, 2019 10:00am
Location: West Hall
Organized By: Department of Statistics

Phylogenomics, the estimation of species phylogenies from genome-scale datasets, is a common step in many biological studies. This estimation is complicated by the fact that genes can evolve under processes, including incomplete lineage sorting (ILS), gene duplication and loss (GDL) and horizontal gene transfer (HGT), that make their trees conflict with the species history. I will survey recent progress on some statistical questions that arise in this context. Specifically, the identifiability of standard probabilistic models of phylogenomic data will be discussed, as well as the large-sample properties of computationally efficient methods for species tree estimation.

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Workshop / Seminar Fri, 15 Nov 2019 10:57:30 -0500 2019-11-22T10:00:00-05:00 2019-11-22T11:00:00-05:00 West Hall Department of Statistics Workshop / Seminar Roch
HET Seminars | Illuminating the Early Universe with Dark Matter Minihalos (November 22, 2019 3:00pm) https://events.umich.edu/event/69401 69401-17318564@events.umich.edu Event Begins: Friday, November 22, 2019 3:00pm
Location: West Hall
Organized By: Leinweber Center for Theoretical Physics

As remnants of the earliest stages of structure formation, the smallest dark matter halos provide a unique probe of the density fluctuations generated during inflation and the evolution of the Universe shortly after inflation. The absence of early-forming ultra-compact minihalos (UCMHs) establishes an upper bound on the amplitude of the primordial power spectrum on small scales and has been used to constrain inflationary models. I will show how numerical simulations of UCMH formation reveal that these constraints need to be revised because the dark matter annihilation rate within UCMHs is lower than has been assumed. Nevertheless, we have found that minihalos can still provide unrivaled constraints on the small-scale primordial power spectrum. The abundance of minihalos also encodes information about the evolution of the Universe prior to Big Bang nucleosynthesis (BBN). I will discuss how the pre-BBN thermal history can enhance the minihalo population, thereby boosting the dark matter annihilation rate if dark matter is a thermal relic. Conversely, the nonthermal production of dark matter can suppress the small-scale power spectrum. It is therefore possible to use gamma-ray observations and observations of the Lyman-α forest to learn about the origins of dark matter and the evolution of the Universe during its first second.

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Lecture / Discussion Wed, 13 Nov 2019 13:26:28 -0500 2019-11-22T15:00:00-05:00 2019-11-22T16:00:00-05:00 West Hall Leinweber Center for Theoretical Physics Lecture / Discussion West Hall
HEP-Astro Seminar | The Degree of Fine-Tuning in our Universe -- and Possibly Others (November 25, 2019 4:00pm) https://events.umich.edu/event/67018 67018-16796445@events.umich.edu Event Begins: Monday, November 25, 2019 4:00pm
Location: West Hall
Organized By: Department of Physics

The fundamental constants of nature must fall within a range of values in order for the universe to develop structure and ultimately support life. This talk considers the current constraints on these quantities and assesses the degree of fine-tuning required for the universe to be viable. The first step is to determine what parameters are allowed to vary. In the realm of particle physics, we must specify the strengths of the fundamental forces and the particle masses. The relevant cosmological parameters include the density of the universe, the cosmological constant, the abundance of ordinary matter, the dark matter contribution, and the amplitude of primordial density fluctuations. These quantities are constrained by the requirements that the universe lives for a sufficiently long time, emerges from its early epochs with an acceptable chemical composition, and can successfully produce galaxies. On smaller scales, stars and planets must be able to form and function. The stars must have sufficiently long lifetimes and hot surface temperatures. The planets must be large enough to maintain atmospheres, small enough to remain non-degenerate, and contain enough particles to support a biosphere. We also consider specific fine-tuning issues in stars, including the triple alpha reaction that produces carbon, the case of unstable deuterium, and the possibility of stable diprotons. For all of these issues, the goal of this enterprise is to delineate the range of parameter space for which universes can remain habitable.

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Workshop / Seminar Mon, 25 Nov 2019 18:16:09 -0500 2019-11-25T16:00:00-05:00 2019-11-25T17:00:00-05:00 West Hall Department of Physics Workshop / Seminar West Hall
Prioritize Wellness (November 25, 2019 7:00pm) https://events.umich.edu/event/68979 68979-17205328@events.umich.edu Event Begins: Monday, November 25, 2019 7:00pm
Location: West Hall
Organized By: First Year Experience Programs

Throughout the semester, it is important to recharge and take breaks to be prepared. Join us for a mindful break and a chance to reflect on wellness! Stop by at some of our Drop-In stations and grab a sleep kit!

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Well-being Thu, 07 Nov 2019 13:59:12 -0500 2019-11-25T19:00:00-05:00 2019-11-25T20:00:00-05:00 West Hall First Year Experience Programs Well-being Prioritize Wellness Flyer
HEP-Astro Seminar | Dark Matter Searches in LZ and Beyond (December 2, 2019 1:00pm) https://events.umich.edu/event/69733 69733-17392933@events.umich.edu Event Begins: Monday, December 2, 2019 1:00pm
Location: West Hall
Organized By: HEP - Astro Seminars

LZ will be the world's most sensitive dark matter direct detection experiment, starting to take data in Spring 2020. The experiment is located 1 mi underground in the Sanford Underground Research Facility (SURF) in Lead, SD. LZ consists of a central time projection chamber (TPC) containing 7 tonnes of liquid xenon as dark matter target surrounded by an outer detector (OD) with 17 tonnes of gadolinium doped liquid scintillator to veto neutrons. I will highlight my group's research contributions to TPC assembly as well as to design and manufacturing of the OD. I will demonstrate how the equipment we built, combined with my analysis and phenomenological experience, will lead to most the sensitive searches including novel signatures. The use of active veto detectors has been adopted by all upcoming direct dark matter experiments and are indispensable to the future of the field. I will present status of my program to develop novel scintillating detectors including the first concepts for future veto detectors for the next generation of dark matter experiments.

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Workshop / Seminar Wed, 27 Nov 2019 09:41:07 -0500 2019-12-02T13:00:00-05:00 2019-12-02T14:00:00-05:00 West Hall HEP - Astro Seminars Workshop / Seminar West Hall
HEP-Astro Seminar | SUSY Searches with ATLAS and Potential Improvements from Track Triggers (December 2, 2019 4:00pm) https://events.umich.edu/event/66923 66923-16787709@events.umich.edu Event Begins: Monday, December 2, 2019 4:00pm
Location: West Hall
Organized By: Department of Physics

The lack of evidence for SUSY at the LHC motivates new search strategies such as looking for scenarios with small mass differences between SUSY particles. However, this can bring challenges because of lower momentum visible decay products. SUSY searches with two leptons offer the possibility to use unique shapes in the invariant mass spectrum as an additional discriminant. In this talk, I will go through the details of ATLAS SUSY searches with two leptons, and show some highlights of recent SUSY results. Additionally, I will discuss how track triggers can enhance the discovery reach of these searches, focusing on the ATLAS Fast TracKer as an example along with its Phase-II counterpart.

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Workshop / Seminar Mon, 02 Dec 2019 18:16:24 -0500 2019-12-02T16:00:00-05:00 2019-12-02T17:00:00-05:00 West Hall Department of Physics Workshop / Seminar West Hall
CM-AMO Seminar | Double Feature - Observation of a Ferro-Rotational Order Coupled with Second-Order Nonlinear Optical Fields & Information Scrambling in Quantum Phases (December 3, 2019 4:00pm) https://events.umich.edu/event/66974 66974-16789923@events.umich.edu Event Begins: Tuesday, December 3, 2019 4:00pm
Location: West Hall
Organized By: Department of Physics

Elizabeth Drueke
U-M Physics

Observation of a Ferro-rotational Order Coupled with Second-order Nonlinear Optical Fields

In this talk, I will discuss our recent discovery of ferrorotational order in RbFe(MoO4)2. Classified by an order parameter which is an axial vector invariant under both time-reversal and spatial-inversion operations, this order is closely related to a number of phenomena such as polar vortices, giant magnetoelectric coupling and spin-helicity-driven ferroelectricity, but it has received little attention so far. Here, using high-sensitivity rotational-anisotropy second-harmonic generation, we have exploited the electric quadrupole contribution to the second harmonic generation to directly couple to this centrosymmetric ferro-rotational order in an archetype of type-II multiferroics, RbFe(MoO4)2. We found that two domain states with opposite ferro-rotational vectors emerge with distinct populations at the critical temperature Tc ≈ 195 K and gradually evolve to reach an even ratio at lower temperatures. Moreover, we have identified the ferro-rotational order phase transition as weakly first order and have revealed its coupling field as a unique combination of the induced electric quadrupole second-harmonic generation and the incident fundamental electric fields.


Ceren Dag
U-M Physics

Information Scrambling in Quantum Phases

Out-of-time-order correlators (OTOCs) are well-established tools for studying quantum chaos in quantum many-body systems as well as information properties of black holes. They characterize the information scrambling which is a dynamical phenomenon where both spatial and temporal correlations spread across a many-body system. Recently an unexpected relation between symmetry-breaking quantum phase transitions and information scrambling has been numerically observed. We introduce a new theoretical tool to understand the reasons and the mechanism of this relation, which makes the dynamical detection of long-range ordered quantum phases via OTOCs intuitive. Based on the studies in literature and our numerical results in the XXZ model, our method renders the relation between information scrambling and quantum phase transitions universal.

Speaker Information: Ceren B. Dag is a graduate student in the Physics Department at the University of Michigan Ann Arbor. She works towards her PhD thesis with Kai Sun and Luming Duan.

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Workshop / Seminar Mon, 02 Dec 2019 09:38:15 -0500 2019-12-03T16:00:00-05:00 2019-12-03T17:00:00-05:00 West Hall Department of Physics Workshop / Seminar West Hall
HET SEMINAR | Extending the Double Copy (December 4, 2019 12:00pm) https://events.umich.edu/event/69764 69764-17417427@events.umich.edu Event Begins: Wednesday, December 4, 2019 12:00pm
Location: West Hall
Organized By: Leinweber Center for Theoretical Physics

I will discuss several recent papers on the double copy. In the first part of the talk I will recap work extending the classical double copy correspondence to maximally symmetric curved spacetimes. I will describe how to construct the corresponding single and zeroth copies in asymptotically (A)dS spacetimes in Kerr-Schild form, and will clarify the interpretation of these copies using several examples, pointing out some peculiar features. In the second part of the talk, I will introduce Galileon fields, and will discuss how to generalize and extend the procedure relating gauge and gravity theories through color-kinematics replacements by showing that the classical perturbative double copy of pions corresponds to special Galileons. I will also show how to construct the single copy by mapping the bi-adjoint scalar radiation to the non-linear sigma model radiation through generalized color-kinematics replacements. Finally, if time permits, I will introduce work studying the double copy beyond leading order.

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Lecture / Discussion Mon, 25 Nov 2019 12:25:35 -0500 2019-12-04T12:00:00-05:00 2019-12-04T13:00:00-05:00 West Hall Leinweber Center for Theoretical Physics Lecture / Discussion West Hall
Department Colloquium | Controlling Dissipation in Superconductors: the Oxymoron that Leads to New Superconducting Phases and Transitions (December 4, 2019 4:00pm) https://events.umich.edu/event/65286 65286-16565505@events.umich.edu Event Begins: Wednesday, December 4, 2019 4:00pm
Location: West Hall
Organized By: Department of Physics

Superconductors are exciting materials for basic physics and applications because they conventionally exhibit zero-resistance and zero-dissipation (i.e., no energy loss). However, unconventional superconductors—including high-temperature superconductors and hybrid superconductor-normal (S-N) systems relevant to quantum computation—combine superconductivity with dissipative normal metal-like states. Yet dissipation has been difficult to control and parametrize. In this talk, I will discuss electrical transport experiments on hybrid superconductor-normal metal systems where the dissipation is controlled, leading to new understanding of superconducting states and transitions. In particular, I will show how superconductivity is established in granular S-N systems, how metallic states appear in arrays of S-N systems as the normal metal fraction is increased, and how magnetic fields can be used to control a variety of dissipative phase transitions. The results are relevant to understanding the role of dissipation in superconducting systems, and in correlated materials in general.

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Workshop / Seminar Wed, 04 Dec 2019 18:16:23 -0500 2019-12-04T16:00:00-05:00 2019-12-04T17:00:00-05:00 West Hall Department of Physics Workshop / Seminar West Hall
Department Colloquium | Controlling Dissipation in Superconductors: the Oxymoron that Leads to New Superconducting Phases and Transitions (December 4, 2019 4:00pm) https://events.umich.edu/event/67181 67181-16805264@events.umich.edu Event Begins: Wednesday, December 4, 2019 4:00pm
Location: West Hall
Organized By: Undergrad Physics Events

Superconductors are exciting materials for basic physics and applications because they conventionally exhibit zero-resistance and zero-dissipation (i.e., no energy loss). However, unconventional superconductors—including high-temperature superconductors and hybrid superconductor-normal (S-N) systems relevant to quantum computation—combine superconductivity with dissipative normal metal-like states. Yet dissipation has been difficult to control and parametrize. In this talk, I will discuss electrical transport experiments on hybrid superconductor-normal metal systems where the dissipation is controlled, leading to new understanding of superconducting states and transitions. In particular, I will show how superconductivity is established in granular S-N systems, how metallic states appear in arrays of S-N systems as the normal metal fraction is increased, and how magnetic fields can be used to control a variety of dissipative phase transitions. The results are relevant to understanding the role of dissipation in superconducting systems, and in correlated materials in general.

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Workshop / Seminar Mon, 25 Nov 2019 08:09:38 -0500 2019-12-04T16:00:00-05:00 2019-12-04T17:00:00-05:00 West Hall Undergrad Physics Events Workshop / Seminar West Hall
Statistics Department Seminar Series: Yuqi Gu, Ph.D. Candidate, Department of Statistics, University of Michigan (December 6, 2019 10:00am) https://events.umich.edu/event/69647 69647-17376499@events.umich.edu Event Begins: Friday, December 6, 2019 10:00am
Location: West Hall
Organized By: Department of Statistics

In modern psychological and biomedical research with diagnostic purposes, scientists often formulate the key task as inferring the fine-grained latent information under structural constraints. These structural constraints usually come from the domain experts’ prior knowledge or insight. The emerging family of Structured Latent Attribute Models (SLAMs) accommodate these modeling needs and have received substantial attention in psychology, education, and epidemiology. SLAMs bring exciting opportunities and unique challenges. In particular, with high-dimensional discrete latent attributes and structural constraints encoded by a design matrix, one needs to balance the gain in the model’s explanatory power and interpretability, against the difficulty of understanding and handling the complex model structure.

In the first part of this talk, I present identifiability results that advance the theoretical knowledge of how the design matrix influences the estimability of SLAMs. The new identifiability conditions guide real-world practices of designing cognitive diagnostic tests and also lay the foundation for drawing valid statistical conclusions. In the second part, I introduce a statistically consistent penalized likelihood approach to selecting significant latent patterns in the population. I also propose a scalable computational method. These developments explore an exponentially large model space involving many discrete latent variables, and they address the estimation and computation challenges of high-dimensional SLAMs arising in large-scale scientific measurements. The application of the proposed methodology to the data from an international educational assessment reveals meaningful knowledge structures and latent subgroups of the student populations.

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Workshop / Seminar Wed, 20 Nov 2019 13:22:35 -0500 2019-12-06T10:00:00-05:00 2019-12-06T11:00:00-05:00 West Hall Department of Statistics Workshop / Seminar Yuqi Gu
Life After Graduate School Seminar | From Natural Laws to Writing Laws: A Physicist Turned Policymaker (December 6, 2019 12:00pm) https://events.umich.edu/event/67593 67593-16900781@events.umich.edu Event Begins: Friday, December 6, 2019 12:00pm
Location: West Hall
Organized By: Department of Physics

The US federal government touches all aspects of our lives through its ~$4.5 trillion annual budget (although less than 4% is for research and development), laws, regulations, rules, and policies. Dr. Anna Quider will discuss her experience as a physicist-turned-policymaker working within the federal government at the U.S. House of Representatives and U.S. Department of State, and external to the federal government as a higher education and science advocate. Attendees will learn about career paths into federal policymaking and how input from physicists and the public inform the federal policymaking process. Dr. Quider is presently the Assistant Vice President for Federal Relations for Northern Illinois University and the past-president of The Science Coalition, a national nonprofit dedicated to increasing US federal funding for fundamental scientific research. She was a 2011 APS Congressional Science Fellow and 2012 AAAS Science and Technology Policy Fellow.


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Workshop / Seminar Fri, 06 Dec 2019 18:16:18 -0500 2019-12-06T12:00:00-05:00 2019-12-06T13:00:00-05:00 West Hall Department of Physics Workshop / Seminar West Hall
HET Seminar | UV and IR properties of quantum gravity from amplitudes (December 6, 2019 3:00pm) https://events.umich.edu/event/69833 69833-17433861@events.umich.edu Event Begins: Friday, December 6, 2019 3:00pm
Location: West Hall
Organized By: Leinweber Center for Theoretical Physics

Using the general unitarity cuts method and amplitudes approach, we calculate the 4-point all-plus-helicity graviton amplitudes at 2-loop. This reproduces a well-known result about 2-loop divergence in quantum gravity, and more importantly, we figure out a very simple renormalization scale dependence of gravity theories at 2-loop. And from this scale dependence, we conclude the duality between scalar and 2-form, between 3-form and cosmological constant at quantum level. And after this direct but complicated calculation, we figure out an alternative simple derivation by doing the cuts and integration in 4d, instead of 4-2e dimension. This elucidates the ultraviolet(UV) physics within. Besides, using techniques from amplitudes, we calculate the bending angle of massless projectiles, including graviton, when they pass near a massive object, like the sun, which is represented by a massive scalar. This reveals the long-distance/infrared(IR) properties of quantum gravity, without worrying about the UV details. And we obtain different bending angles for different massless projectile with different spins, which could possibly indicate a violation of classical equivalence principle at quantum level.

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Lecture / Discussion Wed, 27 Nov 2019 13:50:43 -0500 2019-12-06T15:00:00-05:00 2019-12-06T16:00:00-05:00 West Hall Leinweber Center for Theoretical Physics Lecture / Discussion West Hall
Quantitative Biology Seminar | Morphogen Dynamics Control Patterning in a Stem Cell Model of the Human Embryo (December 9, 2019 12:00pm) https://events.umich.edu/event/68969 68969-17205310@events.umich.edu Event Begins: Monday, December 9, 2019 12:00pm
Location: West Hall
Organized By: Department of Physics

During embryonic development, diffusible signaling molecules called morphogens are thought to determine cell fates in a concentration-dependent manner, and protocols for directed stem cell differentiation are based on this picture. However, in the mammalian embryo, morphogen concentrations change rapidly compared to the time for making cell fate decisions. It is unknown how changing ligand levels are interpreted, and whether the precise timecourse of ligand exposure plays a role in cell fate decisions. In this talk I will discuss our work to address this question using human embryonic stem cells (hESCs), focusing on the dynamics of two morphogens that are crucial for vertebrate gastrulation: Nodal and BMP4. We showed that the response of hESCs to BMP4 signaling is indeed is determined by the ligand concentration, but that unexpectedly, the expression of many mesodermal targets of Nodal depends on the rate of concentration increase. In addition, we showed that a stem cell model for the human embryo generates a wave of Nodal signaling with cells experiencing rapidly increasing Nodal specifically in the region of mesendoderm differentiation. The BMP4 and Nodal pathways share the signal transducer Smad4. Using live imaging of hESCs with GFP integrated at the endogenous SMAD4 locus combined with Fluorescence Recovery After Photobleaching (FRAP), we demonstrated that response to rate of Activin change is due to adaptive signaling, which relies on sequestration of SMAD4. We also demonstrated that pulsatile stimulation with Activin induces repeated strong signaling and enhances mesoderm differentiation. Our results break with the paradigm of concentration-dependent differentiation and demonstrate an important role for morphogen dynamics in the cell fate decisions associated with mammalian gastrulation. They suggest a highly dynamic picture of embryonic patterning where some cell fates depend on rapid concentration increase rather than on absolute levels, and point to ligand dynamics as a new dimension to optimize protocols for directed stem cell differentiation.

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Workshop / Seminar Mon, 09 Dec 2019 18:16:12 -0500 2019-12-09T12:00:00-05:00 2019-12-09T13:00:00-05:00 West Hall Department of Physics Workshop / Seminar West Hall
Statistics Department Seminar Series: Zheng Gao, Ph.D. Candidate, Department of Statistics, University of Michigan (December 10, 2019 4:00pm) https://events.umich.edu/event/69697 69697-17382665@events.umich.edu Event Begins: Tuesday, December 10, 2019 4:00pm
Location: West Hall
Organized By: Department of Statistics

We shall revisit some phase transitions in high-dimensional multiple testing problems under sparsity assumptions, and then proceed to characterize some new ones that we recently discovered. In particular, I will describe the signal sizes necessary and sufficient for statistical procedures to simultaneously control false discovery (in terms of family-wise error rate or false discovery rate) and missed detection (in terms of family-wise non-discovery rate or false non-discovery rate) in the simple but ubiquitous signal-plus-noise model

x(i) = \mu(i) + \epsilon(i), \quad i=1,2,\ldots,p

Several well-known procedures are shown to attain said boundaries. Remarkably, these phase transition phenomena continue to hold under a much wider class of models, and under extremely weak dependence assumptions. We provide point-wise, rather than minimax, results, wherever we can. Important practical implications, along with an interesting manifestation of the phase transitions in genome-wide association studies (GWAS), will be discussed.

Behind the statistical results is a probabilistic phenomenon known as relative stability. Much like how the law of large numbers describes the concentration of averages, relative stability --- or the "law of large dimensions" --- describes the concentration of maxima. We provide a complete characterization of the relative stability phenomenon for Gaussian triangular arrays in terms of their correlation structure. Its proof uses classic Sudakov-Fernique and Slepian lemma arguments along with a curious application of Ramsey's coloring theorem.

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Workshop / Seminar Tue, 26 Nov 2019 15:09:11 -0500 2019-12-10T16:00:00-05:00 2019-12-10T17:00:00-05:00 West Hall Department of Statistics Workshop / Seminar Zheng Gao
Poetry & Ethnography: Expanding the Narrative (December 13, 2019 12:00pm) https://events.umich.edu/event/70194 70194-17547062@events.umich.edu Event Begins: Friday, December 13, 2019 12:00pm
Location: West Hall
Organized By: Department of Anthropology

December 13, 2019
Writing Workshop 12 - 2 pm
111 West Hall
Public Lecture 4 - 5:30 pm
Hatcher Graduate Library Gallery

Please join us for the second event of the
Anthropology & Poetry Speaker and Workshop Series. All students, faculty, and staff are welcome.

The generative writing workshop will be held in 111 West Hall from 12 - 2:00 pm. Participants are invited to bring their own materials (field notes, interview transcriptions, photos, etc.) to work with during the writing workshop, although this is not required. No prior experience with poetry is necessary. Lunch will be provided.

The public lecture will be held in the Hatcher Gallery from 4:00 - 5:30 pm.
Refreshments will be provided.

Kenzie Allen is a descendant of the Oneida Nation of Wisconsin. She is currently a lecturer at York University, and an R1-Advanced Opportunity Program Fellow and PhD Candidate in English & Creative Writing at the University of Wisconsin—Milwaukee. Her research centers on documentary and visual poetics, literary cartography, and the enactment of Indigenous sovereignties through creative works. Kenzie’s most recent project is a multimodal book of poetry which incorporates intergenerational histories and diasporic movements, Haudenosaunee traditions, and archival materials of the Carlisle Indian Boarding School. She received her MFA in Poetry from the Helen Zell Writers’ Program at the University of Michigan, and her BA in Anthropology from Washington University in St. Louis. Her poems can be found in Boston Review, Narrative Magazine, Best New Poets, and other venues, and she is the founder and managing editor of the Anthropoid collective.

Thank you to our sponsors: Department of Anthropology, Rackham Graduate School, Department of English Language and Literature, Department of American Culture, Native American Studies, Native American and Indigenous Studies Interest Group, Institute for the Humanities, LSA, Poetry & Poetics Workshop, Latina/o Studies, and the Center for Latin American and Caribbean Studies.

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Workshop / Seminar Wed, 11 Dec 2019 09:45:59 -0500 2019-12-13T12:00:00-05:00 2019-12-13T14:00:00-05:00 West Hall Department of Anthropology Workshop / Seminar Oneida Big Apple Fest
CM Theory Seminar | Imaging Nematic Quantum Hall States and their Interacting Boundary Modes (January 9, 2020 4:00pm) https://events.umich.edu/event/70881 70881-17728770@events.umich.edu Event Begins: Thursday, January 9, 2020 4:00pm
Location: West Hall
Organized By: Department of Physics

Two-dimensional quantum Hall systems offer a versatile platform to explore the interplay between topology and symmetry breaking facilitated by Coulomb interactions. In this talk, I discuss the novel phenomena that arise from spontaneous valley ordering of bismuth surface states in a large magnetic field. Specifically, we observe the emergence of a nematic phase which breaks the rotational symmetry of the underlying crystal and a ferroelectric phase that carries an in-plane electric dipole moment. We use a scanning tunneling microscope to identify and directly image the wavefunctions of these broken-symmetry quantum Hall phases. Furthermore, we explore the boundary between distinct nematic domains, which host counter-propagating 1D modes. By changing the number of modes, we realize strikingly different regimes where the boundary is either metallic or insulating, constrained by Coulomb interactions between these 1D modes.

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Workshop / Seminar Thu, 09 Jan 2020 18:16:31 -0500 2020-01-09T16:00:00-05:00 2020-01-09T17:00:00-05:00 West Hall Department of Physics Workshop / Seminar West Hall
HET Seminar | Searching for Dark Matter Interactions in Cosmology (January 10, 2020 3:00pm) https://events.umich.edu/event/70973 70973-17760246@events.umich.edu Event Begins: Friday, January 10, 2020 3:00pm
Location: West Hall
Organized By: Leinweber Center for Theoretical Physics

There is a substantial effort in the physics community to search for dark matter interactions with the Standard Model of particle physics. Collisions between dark matter particles and baryons exchange heat and momentum in the early Universe, enabling a search for dark matter interactions using cosmological observations in a parameter space that is complementary to that of direct detection. In this talk, I will describe the effects of scattering in cosmology and show constraints using Planck 2015 data and SDSS-identified satellite galaxies of the Milky Way. I will also discuss the implications of late-time scattering during the era of Cosmic Dawn.

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Lecture / Discussion Mon, 06 Jan 2020 16:50:40 -0500 2020-01-10T15:00:00-05:00 2020-01-10T16:00:00-05:00 West Hall Leinweber Center for Theoretical Physics Lecture / Discussion West Hall
Special CM Theory Seminar | Photoinduced Transformation of Nanoscale Domains in Ferroelectric Complex Oxides (January 13, 2020 1:00pm) https://events.umich.edu/event/71126 71126-17779236@events.umich.edu Event Begins: Monday, January 13, 2020 1:00pm
Location: West Hall
Organized By: Department of Physics

Complex oxide materials are an intense and exciting research area of condensed matter physics with their coupling between lattice, charge, and spin. Especially, nanoscale periodic polar configurations in ferroic oxides called ferroelectric domains exhibit novel phenomena leading to an intense flurry of research interests. However, as studies of functional responses to external stimuli have mainly focused on electric and mechanical responses, a new and effective approach to manipulate these polar configurations is on demand. In this presentation, I will discuss our efforts to investigate interaction of light with nanoscale domains and ferroelastic domain walls examined by in-situ and time-resolved x-ray diffraction experiments. By tracking temporal evolution of x-ray domain diffuse scattering, we have found that structural transformation of ferroic domains is optically induced and exhibits nonthermal characteristics. I will also present theoretical considerations to investigate the underlying physics of the photoinduced transformation.

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Workshop / Seminar Mon, 13 Jan 2020 18:16:32 -0500 2020-01-13T13:00:00-05:00 2020-01-13T14:00:00-05:00 West Hall Department of Physics Workshop / Seminar West Hall
MLK Day Department Colloquium | Creating our Future: Attracting and Retaining the Best Students from All Backgrounds (January 15, 2020 4:00pm) https://events.umich.edu/event/71015 71015-17768616@events.umich.edu Event Begins: Wednesday, January 15, 2020 4:00pm
Location: West Hall
Organized By: Department of Physics

Physics now must compete for the best and brightest. How do we collectively locate, nurture, and advance students who will become our colleagues regardless of opportunities they may or may not have had as they began their studies? There is good evidence that strategies used to attract us into the field are missing large numbers of capable and eager students. I will discuss programs and new approaches that are opening the door to students who may not have felt welcome in the past, but who are now bringing their insights and hard work to solving the next generation of physics problems. We will discuss how the Michigan physics department can help with and benefit from these programs.

This is an inaugural MLK Day Department Colloquium.

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Workshop / Seminar Wed, 15 Jan 2020 18:16:44 -0500 2020-01-15T16:00:00-05:00 2020-01-15T17:00:00-05:00 West Hall Department of Physics Workshop / Seminar West Hall
Statistics Department Seminar Series: Yixin Wang, Ph.D. Candidate, Department of Statistics, Columbia University (January 17, 2020 10:00am) https://events.umich.edu/event/69914 69914-17483044@events.umich.edu Event Begins: Friday, January 17, 2020 10:00am
Location: West Hall
Organized By: Department of Statistics

Causal inference from observational data is a vital problem, but it comes with strong assumptions. Most methods assume that we observe all confounders, variables that affect both the causal variables and the outcome variables. But whether we have observed all confounders is a famously untestable assumption. We describe the deconfounder, a way to do causal inference from observational data allowing for unobserved confounding.

How does the deconfounder work? The deconfounder is designed for problems of multiple causal inferences: scientific studies that involve many causes whose effects are simultaneously of interest. The deconfounder uses the correlation among causes as evidence for unobserved confounders, combining unsupervised machine learning and predictive model checking to perform causal inference. We study the theoretical requirements for the deconfounder to provide unbiased causal estimates, along with its limitations and tradeoffs. We demonstrate the deconfounder on real-world data and simulation studies.

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Workshop / Seminar Fri, 10 Jan 2020 11:21:57 -0500 2020-01-17T10:00:00-05:00 2020-01-17T11:00:00-05:00 West Hall Department of Statistics Workshop / Seminar Yixin Wang
CM-AMO Seminar | Probes of Novel Electronic States in Mesoscopic and 2D Quantum Materials (January 21, 2020 4:00pm) https://events.umich.edu/event/71240 71240-17794027@events.umich.edu Event Begins: Tuesday, January 21, 2020 4:00pm
Location: West Hall
Organized By: Department of Physics

Recent advances in the development of exfoliated 2D materials and other mesoscopic systems (e.g. semiconducting nanowires) have led to the discovery of intriguing topological, magnetic, and superconducting states. However, many bulk probes which have been invaluable in understanding complex electronic states such as those found in high-temperature superconductors are no longer applicable. Additionally, many scanned probes which can study physics on the nanoscale are incompatible with the highest quality, state-of-the-art 2D materials-based devices which rely on encapsulation with hexagonal boron nitride. In this talk I will present magnetic imaging studies of more traditional mesoscopic systems, including imaging current distributions in micron-scale devices and studying novel nanowire-based superconducting devices. Secondly, I will describe more recent work realizing low-disorder graphene devices which facilitated the discovery of new topological states of matter. Finally, I will discuss prospects for studying 2D materials both with magnetic imaging and on-chip THz spectroscopy using superconductivity in exfoliated flakes as an example.

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Workshop / Seminar Tue, 21 Jan 2020 18:17:05 -0500 2020-01-21T16:00:00-05:00 2020-01-21T17:00:00-05:00 West Hall Department of Physics Workshop / Seminar West Hall
Department Colloquium | Nuclear Physics from the Standard Model (January 22, 2020 4:00pm) https://events.umich.edu/event/70952 70952-17760228@events.umich.edu Event Begins: Wednesday, January 22, 2020 4:00pm
Location: West Hall
Organized By: Department of Physics

I will discuss the status and future of calculations of nuclei based on the Standard Model of particle physics. With advances in supercomputing, we are beginning to quantitatively understand nuclear structure and interactions directly from the fundamental quark and gluon degrees of freedom. Recent studies provide insight into the neutrino-nucleus interactions relevant to long-baseline neutrino experiments, double beta decay, and theory predictions of dark matter cross-sections at underground detectors. I will also address new work constraining the gluonic structure of nuclei, which will be measurable for the first time at a future electron-ion collider, and explain how machine learning tools are providing new possibilities in this field.

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Workshop / Seminar Wed, 22 Jan 2020 18:16:59 -0500 2020-01-22T16:00:00-05:00 2020-01-22T17:00:00-05:00 West Hall Department of Physics Workshop / Seminar West Hall
Statistics Department Seminar Series: Rina Foygel Barber, Associate Professor, Department of Statistics, University of Chicago (January 24, 2020 10:00am) https://events.umich.edu/event/69910 69910-17483043@events.umich.edu Event Begins: Friday, January 24, 2020 10:00am
Location: West Hall
Organized By: Department of Statistics

Abstract: We introduce the jackknife+, a novel method for constructing predictive confidence intervals that is robust to the distribution of the data. The jackknife+ modifies the well-known jackknife (leave-one-out cross-validation) to account for the variability in the fitted regression function when we subsample the training data. Assuming exchangeable training samples, we prove that the jackknife+ permits rigorous coverage guarantees regardless of the distribution of the data points, for any algorithm that treats the training points symmetrically. Such guarantees are not possible for the original jackknife and we demonstrate examples where the coverage rate may actually vanish. Our theoretical and empirical analysis reveals that the jackknife and jackknife+ intervals achieve nearly exact coverage and have similar lengths whenever the fitting algorithm obeys some form of stability. We also extend to the setting of K-fold cross-validation. Our methods are related to cross-conformal prediction proposed by Vovk [2015] and we discuss connections.

This work is joint with Emmanuel Candes, Aaditya Ramdas, and Ryan Tibshirani.

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Workshop / Seminar Wed, 15 Jan 2020 10:18:08 -0500 2020-01-24T10:00:00-05:00 2020-01-24T11:00:00-05:00 West Hall Department of Statistics Workshop / Seminar Rina Foygel Barber
Supporting Students and Colleagues with Mental Health Challenges, a Practical Workshop (January 24, 2020 11:00am) https://events.umich.edu/event/71744 71744-17877259@events.umich.edu Event Begins: Friday, January 24, 2020 11:00am
Location: West Hall
Organized By: Physics Workshops & Conferences

Based on faculty interest, the Physics DEI committee is sponsoring an interactive workshop focused on practical strategies for supporting students and colleagues who may be experiencing mental health challenges. Refreshments will be served.

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Workshop / Seminar Mon, 20 Jan 2020 10:50:17 -0500 2020-01-24T11:00:00-05:00 2020-01-24T12:00:00-05:00 West Hall Physics Workshops & Conferences Workshop / Seminar West Hall
Andrew Wetzel: Simulating the Milky Way (January 24, 2020 1:00pm) https://events.umich.edu/event/71427 71427-17825687@events.umich.edu Event Begins: Friday, January 24, 2020 1:00pm
Location: West Hall
Organized By: Michigan Institute for Computational Discovery and Engineering

Abstract: The Gaia satellite mission, together with a multitude of ground-based observational surveys, now measure 6-D phase-space coordinates and multi-species elemental abundances for hundreds of millions of stars across the Milky Way. This new era of galactic archeology and near-field cosmology demands a new generation of simulations that achieve high dynamic range to resolve scales of individual stellar populations within a cosmological context. I will describe the new Latte suite of massively parallelized cosmological zoom-in simulations, run on the nation’s most powerful supercomputers, that model the formation of Milky Way-like galaxies at parsec-scale resolution, using the FIRE (Feedback in Realistic Environments) model for star formation and feedback. First I will discuss the formation of the Milky Way disk, including resolving for the first time the dynamics and lifetimes of giant molecular clouds and stars clusters at z = 0. These simulations also self-consistently resolve the formation of satellite dwarf galaxies around each Milky Way-like host. These low-mass galaxies have presented significant challenges to the cold dark matter model, but I will show progress in addressing the “missing satellites” and “too-big-to-fail” problems. Finally, I will discuss synthetic Milky Way surveys that we have created from the Latte simulations, which are publicly available, to provide theoretical modeling insight for the era of Gaia.

Bio: Professor Wetzel is an assistant professor in the physics department and in the astrophysics and cosmology group at the University of California, Davis. He is a theoretical/computational astrophysicist and cosmologist. Using the world’s most powerful supercomputers, he generates cosmological simulations to model the formation of cosmic structures, including galaxies and their stars. He uses these simulations as theoretical laboratories to develop and test models of galaxy formation, stellar dynamics, and the nature of dark matter, with emphasis on our own Milky Way galaxy.

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Workshop / Seminar Tue, 14 Jan 2020 10:59:20 -0500 2020-01-24T13:00:00-05:00 2020-01-24T14:00:00-05:00 West Hall Michigan Institute for Computational Discovery and Engineering Workshop / Seminar A. Wetzel
HET Seminar | Bit threads and holographic monogamy (January 24, 2020 3:00pm) https://events.umich.edu/event/71113 71113-17777078@events.umich.edu Event Begins: Friday, January 24, 2020 3:00pm
Location: West Hall
Organized By: Leinweber Center for Theoretical Physics

Entanglement entropies are well-studied in holographic field theories thanks to the Ryu-Takayanagi formula. Bit threads offer a conceptually and technically powerful new way to think about this formula. In this talk, after introducing bit threads, I will use them to give a new understanding of the so-called monogamy property of holographic entropies. The resulting picture will lead to an intriguing conjecture about the general entanglement structure of holographic states.

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Lecture / Discussion Wed, 08 Jan 2020 14:28:52 -0500 2020-01-24T15:00:00-05:00 2020-01-24T16:00:00-05:00 West Hall Leinweber Center for Theoretical Physics Lecture / Discussion West Hall
HEP-Astro Seminar | New Result on K+→π+vv^- from the NA62 Experiment (January 27, 2020 4:00pm) https://events.umich.edu/event/71101 71101-17777061@events.umich.edu Event Begins: Monday, January 27, 2020 4:00pm
Location: West Hall
Organized By: Department of Physics

The decay K+→π+vv^-, with a very precisely predicted branching ratio of less than 10exp(-10), is one of the best candidates to reveal indirect effects of new physics at the highest mass scales. The NA62 experiment at the CERN SPS is designed to measure the branching ratio of the K+ → π+vv^- with a decay-in-flight technique. NA62 took data so far in 2016-2018. Statistics collected in 2016 allowed NA62 to reach the Standard Model sensitivity for K+→π+vv^- entering the domain of 10exp(-10) single event sensitivity and showing the proof of principle of the experiment. Thanks to the statistics collected in 2017, NA62 surpasses the present best sensitivity. The analysis strategy is reviewed and the preliminary result from the 2017 data set is presented.

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Workshop / Seminar Mon, 27 Jan 2020 18:17:00 -0500 2020-01-27T16:00:00-05:00 2020-01-27T17:00:00-05:00 West Hall Department of Physics Workshop / Seminar West Hall
Special HEP-Astro Seminar | When Stars Go Nonlinear: Large Amplitude Tides and Stellar Oscillations (January 28, 2020 2:00pm) https://events.umich.edu/event/71215 71215-17787739@events.umich.edu Event Begins: Tuesday, January 28, 2020 2:00pm
Location: West Hall
Organized By: Department of Physics

Tides significantly impact the structure, evolution, and fate of many types of close binary systems, including short-period exoplanets, stellar binaries, and coalescing binary neutron stars. In many of these systems, the tide’s amplitude is so large that it cannot be treated as a small, linear perturbation to the background star. In this talk, I will show that nonlinear effects can greatly enhance the rate of tidal dissipation and thus the rate of binary evolution. As examples, I will describe how nonlinear tides influence the orbital decay of hot Jupiters and the gravitational-wave signal of coalescing binary neutron stars and white dwarfs. I will also discuss the nonlinearity of oscillation-modes in solar-like stars, which are excited by turbulent motions within the convective envelope. The rich oscillation spectra observed by space missions such as Kepler and TESS has revolutionized the field of asteroseismology and yielded a wealth of information about the internal and global properties of thousands of stars.

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Workshop / Seminar Tue, 28 Jan 2020 18:16:58 -0500 2020-01-28T14:00:00-05:00 2020-01-28T15:00:00-05:00 West Hall Department of Physics Workshop / Seminar West Hall
Department Colloquium | New Ideas in Dark Matter Detection (January 29, 2020 4:00pm) https://events.umich.edu/event/71102 71102-17777062@events.umich.edu Event Begins: Wednesday, January 29, 2020 4:00pm
Location: West Hall
Organized By: Department of Physics

The nature of the dark matter remains one of the most compelling outstanding questions in physics. Theoretical and experimental focus has been directed in the last several decades on New Physics at the weak scale, including the search for dark matter as a Weakly Interacting Massive Particle (WIMP). We are now looking beyond the WIMP window towards light hidden sectors, and new ideas to search for dark matter must be found. I describe some of these new ideas, including collective excitations in polar materials and superfluid helium, as well as low-gap targets like Dirac semimetals.

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Workshop / Seminar Wed, 29 Jan 2020 18:17:10 -0500 2020-01-29T16:00:00-05:00 2020-01-29T17:00:00-05:00 West Hall Department of Physics Workshop / Seminar West Hall
Statistics Department Seminar Series: Dylan Small, Professor, Department of Statistics, The Wharton School, University of Pennsylvania (January 31, 2020 10:00am) https://events.umich.edu/event/69915 69915-17483046@events.umich.edu Event Begins: Friday, January 31, 2020 10:00am
Location: West Hall
Organized By: Department of Statistics

Gun violence is a problem in America. There are many unresolved questions about what policies would reduce gun violence. I will discuss two attempts at causal inference about gun violence prevention policies that I have worked on, and highlight some ideas about causal inference I have sought to use in this work.

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Workshop / Seminar Fri, 10 Jan 2020 12:13:43 -0500 2020-01-31T10:00:00-05:00 2020-01-31T11:00:00-05:00 West Hall Department of Statistics Workshop / Seminar Dylan Small
Accelerated Master's Degree Program in Statistics Info Session (January 31, 2020 1:00pm) https://events.umich.edu/event/72097 72097-17937824@events.umich.edu Event Begins: Friday, January 31, 2020 1:00pm
Location: West Hall
Organized By: Department of Statistics

Are you an undergraduate student interested in a master’s degree in Applied Statistics? Join us for an info session all about our Accelerated Master’s Degree Program (AMDP) in Applied Statistics!

The AMDP option is for highly-motivated undergraduate students in their senior year who will achieve their MS in Applied Statistics with one more year of graduate study. Students typically apply in the 2nd semester of their junior year.

If this is something you’re considering for the future, join us for the info session to ask questions and learn about the application process, program requirements and timeline!

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Meeting Mon, 27 Jan 2020 11:57:36 -0500 2020-01-31T13:00:00-05:00 2020-01-31T14:00:00-05:00 West Hall Department of Statistics Meeting West Hall
HEP-Astro Seminar | Ultra-Low Energy Calibration of the LUX and LZ Dark Matter Detectors (February 3, 2020 4:00pm) https://events.umich.edu/event/71241 71241-17794028@events.umich.edu Event Begins: Monday, February 3, 2020 4:00pm
Location: West Hall
Organized By: Department of Physics

The Large Underground Xenon (LUX) experiment is a 250 kg active mass dual-phase time-projection chamber (TPC) operating at the 4850 ft level of the Sanford Underground Research Facility in Lead, SD. Various sources, including ^{127}Xe, D-D neutrons, ^{83}mKr, Tritium, and AmBe neutrons are used to perform calibrations of detector responses to electron recoils (ER) and nuclear recoils (NR). I will present an ultra-low energy calibration of ER using an intrinsic ^{127}Xe source and of NR using a short pulsed D-D neutron generator. Radioactive isotope ^{127}Xe is formed in the LUX LXe volume due to cosmogenic activation before the detector was moved one mile underground. A measurement in the early stage of the LUX WS2013 science run unveils ~0.9 million ^{127}Xe atoms in the LUX LXe volume, which provides an ideal source for low energy calibrations. ^{127}Xe decay is a form of electron capture in which a high energy gamma (> 200 keV) is emitted, followed by an associated low energy X-ray cascade over the energy range of 190 eV to 33.2 keV. The relatively long mean free path (mfp) of the gamma-ray (> 0.9 cm) allows the EC decay to produce clearly identified 2-vertex events in the LUX detector. We observe the K (33.2 keV), L (5.2 keV), M (1.1 keV), and N (190 eV) shell cascade events and verify the relative ratio of observed events for each shell. We extract the means and sigmas of the charge signal yields associated with the K, L, M, and N shell events. The N shell cascade analysis includes single extracted electron (SE) events and represents the lowest-energy electronic recoil in situ measurements that have been explored in liquid xenon. A short pulsed D-D neutron NR calibration was performed in situ in the LUX detector in June 2016 after the completion of the LUX WS2013-16 science run. The calibration incorporates a pulsing technique with narrow pulses (20 us / 250 Hz). We have measured, with low systematics, the absolute rates of NR events with ionization signals down to 2 extracted electrons and zero, one or greater detected scintillation photons. A calibration measurement with absolute event rates of charge-only S2 events for the first time in a Xe TPC provides an important probe for ultra-low energy measurements of LXe Qy. This technique provides direct measurements of scintillation and charge yields down to (Ly) 0.45 keVnr and (Qy) 0.27 keVnr, respectively. New calibration results on ultra-low energy nuclear recoil yields are crucial to determine physics search sensitivities for large mass LXe TPCs (LZ experiment) for low mass WIMPs (< 10 GeV) and for coherent neutrino scattering (e.g. ^8B solar neutrino).

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Workshop / Seminar Mon, 03 Feb 2020 18:16:42 -0500 2020-02-03T16:00:00-05:00 2020-02-03T17:00:00-05:00 West Hall Department of Physics Workshop / Seminar West Hall
Department Colloquium | Approaches to Fully-3D Dedicated Molecular Breast Imaging (February 5, 2020 4:00pm) https://events.umich.edu/event/71066 71066-17770769@events.umich.edu Event Begins: Wednesday, February 5, 2020 4:00pm
Location: West Hall
Organized By: Department of Physics

The Multi-Modality Imaging Lab at Duke has developed and characterized several dedicated (human) breast imaging devices which offer no compression (no pain!), fast scans, low dose imaging with ionizing radiation for the patient, and fully-3D, isotropic, high resolution quantitative in vivo image information for physicians. The first is a “one-stop” dedicated breast imaging system for utilizing in vivo molecular imaging with Single Photon Emission Computed Tomography (SPECT) using a 4x5 array of 4x4cm^2 pixelated CZT modules combined with low dose x-ray Computed Tomography (CT) utilizing a 40x30cm^2 CsI(Tl) flat-panel detector coupled to a TFT array. The subsystems were developed individually, then hybridized onto a single platform, allowing fully-3D motions of each subsystem. The 3D acquisitions facilitate overcoming sampling insufficiency issues associated with cone-beam CT imaging in the pendant breast frame. Novel x-ray filtering leading to quasi-monochromatic spectra have enabled low dose CT imaging comparable with standard mammography, providing quantitative accuracy within a few percent of NIST values, while optimizing dose efficiency for image quality. Next is a clinically available cardiac SPECT imaging system utilizing 19 compact (8x8cm^2) CZT cameras with pinhole collimators reconfigured for uncompressed, pendant breast and chest wall imaging. The third system utilizes LGSO scintillation crystals coupled to compact position-sensitive photodetectors in two opposed 15x20cm^2 flat panels enabling fully-3D acquisition for dedicated breast Positron Emission Tomography (PET) imaging; this open system can be combined with dedicated CT. The most current system design is for dual PET-MRI breast imaging using an ultra-high sensitivity configuration of PET detector modules to image both breasts simultaneously, and is evaluated by Monte Carlo techniques. These systems can be used to detect occult disease not otherwise seen in contemporary x-ray mammography or tomosynthesis, improve the specificity of cancer diagnosis, and monitor therapeutic response in patients, without causing additional pain (or fear) for the patient.

SHORT BIO: Martin Tornai is an Associate Professor of Radiology (tenured) and Biomedical Engineering, and a faculty member of the Medical Physics Graduate Program at Duke University. He has an undergraduate degree in physics from Cornell and a PhD in biomedical physics from UCLA. Upon completing his doctoral research on intraoperative nuclear imaging devices in 1997, he was recruited to the Duke faculty where he has engaged in numerous activities locally, nationally and internationally. He is a founding faculty member of Duke’s Medical Physics Graduate Program which will celebrate it’s 15th anniversary, and is active on many administrative committees, teaching, and student research committees, helping guide students in their research efforts. His research interests include dedicated nuclear (SPECT & PET) and x-ray based (CT) breast imaging devices, with which several dozen women have been clinically scanned. Along with his numerous MS, PhD and post-doctoral students and various colleagues, he has published over 150 original papers, proceedings articles, and book chapters. His newer interests include dosimetry for nuclear medicine theranostic applications.

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Workshop / Seminar Wed, 05 Feb 2020 18:17:08 -0500 2020-02-05T16:00:00-05:00 2020-02-05T17:00:00-05:00 West Hall Department of Physics Workshop / Seminar West Hall
Michigan Institute for Research in Astrophysics Presents: "Conversations on Inclusion and Equity" (February 7, 2020 9:30am) https://events.umich.edu/event/71967 71967-17905471@events.umich.edu Event Begins: Friday, February 7, 2020 9:30am
Location: West Hall
Organized By: Michigan Institute for Research in Astrophysics

“Recommendations for a More Inclusive Canadian Astronomy Community”

The Canadian astronomical community is currently undergoing its "Long Range Planning" process, similar to the Decadal Survey in the US. As such, the Equity and Inclusivity Committee (EIC) has recently shared a white paper with a set of recommendations for improving the representation of minoritized peoples and the working conditions in the professional astronomy community: http://myumi.ch/Bo38l. I'll briefly describe these recommendations and then open an informal discussion of their merit (and what we have inevitably missed!).

Please note: Should you require any reasonable accommodations to ensure equal access and opportunity related to this event please contact Stacy Tiburzi at 734-764-3440 or stibu@umich.edu.

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Lecture / Discussion Thu, 30 Jan 2020 15:16:28 -0500 2020-02-07T09:30:00-05:00 2020-02-07T10:20:00-05:00 West Hall Michigan Institute for Research in Astrophysics Lecture / Discussion Dr. Daryl Haggard
Interdisciplinary Seminar in Quantitative Methods (ISQM) (February 7, 2020 10:00am) https://events.umich.edu/event/72393 72393-18000381@events.umich.edu Event Begins: Friday, February 7, 2020 10:00am
Location: West Hall
Organized By: Interdisciplinary Seminar in Quantitative Methods (ISQM)

The Blessings of Multiple Causes (Joint with Yixin Wang)

ABSTRACT: Causal inference from observational data is a vital problem, but it comes with strong assumptions. Most methods require that we observe all confounders, variables that affect both the causal variables and the outcome variables. But whether we have observed all confounders is a famously untestable assumption. We describe the deconfounder, a way to do causal inference with weaker assumptions than the classical methods require.

How does the deconfounder work? While traditional causal methods measure the effect of a single cause on an outcome, many modern scientific studies involve multiple causes, different variables whose effects are simultaneously of interest. The deconfounder uses the correlation among multiple causes as evidence for unobserved confounders, combining unsupervised machine learning and predictive model checking to perform causal inference. We demonstrate the deconfounder on real-world data and simulation studies, and describe the theoretical requirements for the deconfounder to provide unbiased causal estimates.

David works in the fields of machine learning and Bayesian statistics.

The goal of the Interdisciplinary Seminar in Quantitative Methods is to provide an interdisciplinary environment where researchers can present and discuss cutting-edge research in quantitative methodology. The talks are aimed at a broad audience, with emphasis on conceptual rather than technical issues. The research presented is varied, ranging from new methodological developments to applied empirical papers that use methodology in an innovative way. We welcome speakers and audiences from all disciplines and fields, including the social, natural, biomedical, and behavioral sciences.

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Lecture / Discussion Mon, 03 Feb 2020 12:04:40 -0500 2020-02-07T10:00:00-05:00 2020-02-07T11:00:00-05:00 West Hall Interdisciplinary Seminar in Quantitative Methods (ISQM) Lecture / Discussion David Blei
Statistics Department Seminar Series: David Blei, Professor, Department of Statistics and Computer Science, Columbia University (February 7, 2020 10:00am) https://events.umich.edu/event/69917 69917-17483049@events.umich.edu Event Begins: Friday, February 7, 2020 10:00am
Location: West Hall
Organized By: Department of Statistics

Abstract: Causal inference from observational data is a vital problem, but it comes with strong assumptions. Most methods require that we observe all confounders, variables that affect both the causal variables and the outcome variables. But whether we have observed all confounders is a famously untestable assumption. We describe the deconfounder, a way to do causal inference with weaker assumptions than the classical methods require.

How does the deconfounder work? While traditional causal methods measure the effect of a single cause on an outcome, many modern scientific studies involve multiple causes, different variables whose effects are simultaneously of interest. The deconfounder uses the correlation among multiple causes as evidence for unobserved confounders, combining unsupervised machine learning and predictive model checking to perform causal inference. We demonstrate the deconfounder on real-world data and simulation studies, and describe the theoretical requirements for the deconfounder to provide unbiased causal estimates.

This is joint work with Yixin Wang. [*] https://www.tandfonline.com/doi/full/10.1080/01621459.2019.1686987

Biography: David Blei is a Professor of Statistics and Computer Science at Columbia University, and a member of the Columbia Data Science Institute. He studies probabilistic machine learning, including its theory, algorithms, and application. David has received several awards for his research, including a Sloan Fellowship (2010), Office of Naval Research Young Investigator Award (2011), Presidential Early Career Award for Scientists and Engineers (2011), Blavatnik Faculty Award (2013), ACM-Infosys Foundation Award (2013), a Guggenheim fellowship (2017), and a Simons Investigator Award (2019). He is the co-editor-in-chief of the Journal of Machine Learning Research. He is a fellow of the ACM and the IMS.

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Workshop / Seminar Thu, 30 Jan 2020 10:19:09 -0500 2020-02-07T10:00:00-05:00 2020-02-07T11:00:00-05:00 West Hall Department of Statistics Workshop / Seminar David Blei
HET Seminar | Large Signals in the Cosmological Collider (February 7, 2020 3:00pm) https://events.umich.edu/event/71950 71950-17903308@events.umich.edu Event Begins: Friday, February 7, 2020 3:00pm
Location: West Hall
Organized By: Leinweber Center for Theoretical Physics

Cosmological inflation gives a unique opportunity of probing physics at high energies. In particular, non-Gaussianities contain information on new physics particles being produced through the interaction of the inflatons. In this talk, I will discuss the size of such signals and highlight the scenarios in which we expect it to be observable.

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Lecture / Discussion Thu, 23 Jan 2020 11:53:59 -0500 2020-02-07T15:00:00-05:00 2020-02-07T16:00:00-05:00 West Hall Leinweber Center for Theoretical Physics Lecture / Discussion West Hall
The Michigan Anthropology Colloquia Series: “Historical and Environmental Impacts of Pastoralism: Examining the timing, tempo, and character of animal herding among Europe’s first farmers” (February 7, 2020 3:00pm) https://events.umich.edu/event/63286 63286-15612039@events.umich.edu Event Begins: Friday, February 7, 2020 3:00pm
Location: West Hall
Organized By: Department of Anthropology

"The spread of farming (ca. 8000 years ago) ushered in a new chapter in Europe’s cultural and environmental history. The translocation of plants and animals instigated the reorganization of economic activities that reshaped landscapes, communities, and even human biology. Within this broader context, I present new data from the earliest Neolithic villages on the Dalmatian coast of Croatia to explore the timing, tempo, and nature of Neolithic domestic animal management, and its long-term cultural, biological, and ecological effects in the Adriatic and throughout Europe."

The Michigan Anthropology Colloquia Series presents speakers on current topics in the field of anthropology

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Lecture / Discussion Thu, 09 Jan 2020 14:32:36 -0500 2020-02-07T15:00:00-05:00 2020-02-07T17:00:00-05:00 West Hall Department of Anthropology Lecture / Discussion West Hall
HEP-Astro Seminar | Low-energy Nuclear Recoils for Fun and Profit (February 10, 2020 4:00pm) https://events.umich.edu/event/71764 71764-17879416@events.umich.edu Event Begins: Monday, February 10, 2020 4:00pm
Location: West Hall
Organized By: Department of Physics

I will discuss the rapidly-changing panorama of experiments seeking to measure the faint signals produced by keV and sub-keV nuclear recoils in radiation detectors. The initial interest in this area originated from searches for dark matter WIMPs, but has expanded with the demonstration of coherent elastic neutrino-nucleus scattering. I will elaborate on the difficulties involved in understanding the response of detecting materials to this type of interaction, including some recent developments. I will also emphasize the opportunities for nuclear recoil detectors in areas beyond dark matter detection.

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Workshop / Seminar Mon, 10 Feb 2020 18:16:48 -0500 2020-02-10T16:00:00-05:00 2020-02-10T17:00:00-05:00 West Hall Department of Physics Workshop / Seminar West Hall
Distinguished Alumni Speaker Series: Earl Lawrence, Statistical Sciences, Los Alamos National Laboratory (February 14, 2020 10:00am) https://events.umich.edu/event/69918 69918-17483050@events.umich.edu Event Begins: Friday, February 14, 2020 10:00am
Location: West Hall
Organized By: Department of Statistics

Abstract:
Inference with computationally expensive physics models is a big part of statistics at Los Alamos National Laboratory. The first part of that talk will cover some well-known background on the statistical approach computer experiments. This will take place in the context of ongoing work for ChemCam, an instrument on the Mars rover Curiosity whose goal is to determine whether Mars ever had conditions that could have supported microbial life. ChemCam uses laser-induced breakdown spectroscopy to analyze the chemical composition of Martian soil and rocks. Our goal is to use the resulting spectra and a LANL-developed predictive model to estimate the elemental abundances from surface samples. The second part of the talk will cover new work to address computer experiments from exascale supercomputers. The next generation of supercomputers are expected to have I/O limitations relative to their computing ability: they will simulate more than they can save. This requires changes to our usual post-hoc analysis scheme. To address this, we are developing approaches to in situ statistical inference, statistical modeling that gets done inside simulations as they are running. Our early work considers modeling extremes for climate and space weather.

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Workshop / Seminar Wed, 05 Feb 2020 14:37:54 -0500 2020-02-14T10:00:00-05:00 2020-02-14T11:00:00-05:00 West Hall Department of Statistics Workshop / Seminar Earl Lawrence
HET Seminar | Globally consistent three-family Standard Models in F-theory (February 14, 2020 3:00pm) https://events.umich.edu/event/72170 72170-17948640@events.umich.edu Event Begins: Friday, February 14, 2020 3:00pm
Location: West Hall
Organized By: Leinweber Center for Theoretical Physics

We present recent advances in constructions of globally consistent F-theory compactifications with the exact chiral spectrum of the minimal supersymmetric Standard Model. We highlight the first such example and then turn to a subsequent systematic exploration of the landscape of F-theory three-family Standard Models with a gauge coupling unification. Employing algebraic geometry techniques, all global consistency conditions of these models can be reduced to a single geometric criterion on the base of the underlying elliptically fibered Calabi-Yau four-folds. For toric bases, this criterion only depends on an associated polytope and is satisfied for at least quadrillion bases, each of which defines a distinct compactification. We conclude by pointing out important outstanding issues.

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Lecture / Discussion Tue, 28 Jan 2020 14:33:28 -0500 2020-02-14T15:00:00-05:00 2020-02-14T16:00:00-05:00 West Hall Leinweber Center for Theoretical Physics Lecture / Discussion West Hall
The Michigan Anthropology Colloquia Series: "Aging Patterns in Wild Chimpanzees" (February 14, 2020 3:00pm) https://events.umich.edu/event/68799 68799-17153402@events.umich.edu Event Begins: Friday, February 14, 2020 3:00pm
Location: West Hall
Organized By: Department of Anthropology

"Although chimpanzees have been studied in the wild for almost 60 years, until recently, very little is known about how chimpanzees age both physically and socially. This is surprising given that they can live up to 50-60 years in the wild, well past the prime years of their life. In this talk, Dr. Machanda will highlight recent research from her long-term field site, the Kibale Chimpanzee Project, on the physical, physiological and social aging patterns of wild chimpanzees."

The Michigan Anthropology Colloquia Series presents speakers on current topics in the field of anthropology

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Lecture / Discussion Wed, 05 Feb 2020 09:45:56 -0500 2020-02-14T15:00:00-05:00 2020-02-14T17:00:00-05:00 West Hall Department of Anthropology Lecture / Discussion West Hall
HEP-Astro Seminar | Better Neutrinoless Double Beta Decay through Biochemistry (February 17, 2020 4:00pm) https://events.umich.edu/event/72039 72039-17916368@events.umich.edu Event Begins: Monday, February 17, 2020 4:00pm
Location: West Hall
Organized By: Department of Physics

The goal of future neutrinoless double beta decay experiments is to establish whether neutrino is its own antiparticle, by searching for an ultra-rare decay process with a half life that may be more than 10^27 years. Such a discovery would have major implications for cosmology and particle physics, but requires ton-scale detectors with backgrounds below 1 count per ton per year. This is a formidable technological challenge that has prompted consideration of unconventional solutions. I will discuss an approach being developed within the NEXT collaboration: high pressure xenon gas time projection chambers augmented with single molecule fluorescent imaging-based barium tagging. This combines techniques from the fields of biochemistry, super-resolution microscopy, organic synthesis and nuclear physics, possibly enabling the first effectively background-free, ton-scale neutrinoless double beta decay technology.

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Workshop / Seminar Mon, 17 Feb 2020 18:16:52 -0500 2020-02-17T16:00:00-05:00 2020-02-17T17:00:00-05:00 West Hall Department of Physics Workshop / Seminar West Hall
CRLT Physics Workshop | Moving the Needle: Shifting the Conversation Around Sexual Harassment (February 19, 2020 3:00pm) https://events.umich.edu/event/72372 72372-17998152@events.umich.edu Event Begins: Wednesday, February 19, 2020 3:00pm
Location: West Hall
Organized By: Physics Workshops & Conferences

Part research presentation, part embodied case study, and part community conversation, Moving the Needle: Shifting the Conversation around Sexual Harassment challenges participants to expand their understanding of what sexual harassment is, how it impacts individuals and communities, and what makes an environment ripe for its presence. Using the NASEM consensus study report as both grounding and springboard, this session eschews a "tips and tricks" workshop model, instead pointing attendees toward the ongoing reflective practices that individuals and communities will need to commit to in order to address the culturally embedded problem of sexual harassment.

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Workshop / Seminar Wed, 12 Feb 2020 11:35:07 -0500 2020-02-19T15:00:00-05:00 2020-02-19T17:00:00-05:00 West Hall Physics Workshops & Conferences Workshop / Seminar West Hall
Statistics Department Seminar Series: Bhaswar Bhattacharya, Assistant Professor, Department of Statistics, The Wharton School, University of Pennsylvania (February 21, 2020 10:00am) https://events.umich.edu/event/69919 69919-17483051@events.umich.edu Event Begins: Friday, February 21, 2020 10:00am
Location: West Hall
Organized By: Department of Statistics

Abstract: Two of the fundamental problems in non-parametric statistical inference are goodness-of-fit and two-sample testing. These two problems have been extensively studied and several multivariate tests have been proposed over the last thirty years, many of which are based on geometric graphs. These include, among several others, the celebrated Friedman-Rafsky two-sample test based on the minimal spanning tree and the K-nearest neighbor graphs, and the Bickel-Breiman spacings tests for goodness-of-fit. These tests are asymptotically distribution-free, universally consistent, and computationally efficient (both in sample size and in dimension), making them particularly attractive for modern statistical applications.

In this talk, we will derive the detection thresholds and limiting local power of these tests, thus providing a way to compare and justify the performance of these tests in various applications. Several interesting properties emerge, such as a curious phase transition in dimension 8, and a remarkable blessing of dimensionality in detecting scale changes.

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Workshop / Seminar Fri, 31 Jan 2020 16:34:15 -0500 2020-02-21T10:00:00-05:00 2020-02-21T11:00:00-05:00 West Hall Department of Statistics Workshop / Seminar Bhattacharya
Life In Graduate School Seminar | How to Find a Postdoc Position (February 21, 2020 12:00pm) https://events.umich.edu/event/72814 72814-18079325@events.umich.edu Event Begins: Friday, February 21, 2020 12:00pm
Location: West Hall
Organized By: Life in Graduate School Seminars

Three people with postdoc hunting experience in high energy experiment, computational condensed matter and experimental condensed matter will be invited and present their experience and lessons in finding postdoc positions.

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Workshop / Seminar Wed, 12 Feb 2020 13:31:43 -0500 2020-02-21T12:00:00-05:00 2020-02-21T13:00:00-05:00 West Hall Life in Graduate School Seminars Workshop / Seminar West Hall
HET Seminar | Conical singularities of G2-manifolds in mathematics and physics (February 21, 2020 3:00pm) https://events.umich.edu/event/72414 72414-18000399@events.umich.edu Event Begins: Friday, February 21, 2020 3:00pm
Location: West Hall
Organized By: Leinweber Center for Theoretical Physics

I will first give an introduction to and brief history of G2 geometry, to compare and contrast it to Calabi-Yau geometry. G2 manifolds are important in physics because they admit parallel spinors. It is of interest to construct compact examples with singularities. I will then give a survey of some of my work that is related to conical singularities of G2 manifolds, including: desingularization, deformation theory, and a possible strategy to construct such G2 conifolds. This will include some (separate) joint works with Dominic Joyce and Jason Lotay. No previous exposure to G2 geometry will be assumed, but the focus will be more mathematical than physical. I am hoping that some of you can teach me more physics during the day.

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Lecture / Discussion Mon, 03 Feb 2020 14:25:52 -0500 2020-02-21T15:00:00-05:00 2020-02-21T16:00:00-05:00 West Hall Leinweber Center for Theoretical Physics Lecture / Discussion West Hall
HEP-Astro Seminar | SuperTIGER in Antarctica: The Hunt for Ultra-Heavy Cosmic Rays (February 24, 2020 4:00pm) https://events.umich.edu/event/71016 71016-17768617@events.umich.edu Event Begins: Monday, February 24, 2020 4:00pm
Location: West Hall
Organized By: Department of Physics

The Super Trans-Iron Galactic Element Recorder (SuperTIGER) experiment measures the abundances of the merely relativistic and rare ultra-heavy cosmic rays (UHCR) beyond 26Fe produced in neutron-capture processes. Since the galactic cosmic rays do not point back to their sources we must search for other clues of their origins, and some handles on this are their energy spectra and their detailed elemental and isotopic compositions. The predecessor TIGER instrument made preliminary measurements of UHCR abundances resolving individual elements from 30Zn to 40Zr with two Antarctic flights (2001-2002, 2003-2004) totaling ~50 days. These data support a model of galactic cosmic-ray origins with a dominant contribution from OB association massive star clusters where the source material is enhanced by the outflow and super nova ejecta of these stars (~20%), and in which the more refractory elements that condense into dust grains are preferentially accelerated (~4x) over the volatile ones found as gas. SuperTIGER is over four times the size of TIGER, and with its first 55 day Antarctic flight (2012-2013) confirmed the TIGER findings through 40Zr with good statistics, and with the inclusion of data from a second flight (2019-2020) will extend preliminary UHCR abundance measurements through around 56Ba. Our UHCR observations to date show the galactic cosmic-ray source is enhanced by massive star products over solar system (~5 billion year old ISM), which means this comparatively fresh sample of galactic material can shed light on which heavier elements are significant products of massive stars and their associated supernova (SN) nucleosynthesis. This could help provide constraints on models for the synthesis of heavy elements in binary neutron star mergers (BNSM), for which evidence has been observed in ejected material seen in optical observations following LIGO event GW170817. BNSM are rarer than SN by several orders of magnitude or more, and are unlikely to have contributed to the observed fluxes of the UHCR. I will present on the SuperTIGER science, and the unique challenges and charms of scientific ballooning in Antarctica.

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Workshop / Seminar Mon, 24 Feb 2020 18:16:44 -0500 2020-02-24T16:00:00-05:00 2020-02-24T17:00:00-05:00 West Hall Department of Physics Workshop / Seminar West Hall
CM-AMO Seminar | Emergent Ultrafast Structural Dynamics in Complex Oxides and 2D Materials (February 25, 2020 4:00pm) https://events.umich.edu/event/72099 72099-17939962@events.umich.edu Event Begins: Tuesday, February 25, 2020 4:00pm
Location: West Hall
Organized By: Department of Physics

New properties emerge when material systems “scale up” via uniquely connected individual element, or “scale down” by reducing dimensionality and resulting in symmetry breaking. In this talk, I will show recent efforts to use light pulses at terahertz and x-ray frequencies to stimulate and track emergent dynamical properties of materials on ultrafast time scales. In the “scale-up” example, we observed a new set of collective excitations in polar vortices, named vortexons. A unique soft mode is identified as a pair of oscillating vortex cores that can be significantly tuned by thermal strain around room temperature. The discovery of tunable vortexons opens a new avenue for high-frequency dielectrics and optoelectronics applications. In the “scale-down” example, I will show the distinct structural dynamics of monolayer crystals WSe2 from their bulk counterparts. We found the absorbed optical photon energy is preferably coupled to the in-plane lattice vibrations within one picosecond whereas the out-of-plane lattice vibration amplitude remains unchanged during the first ten picoseconds, marking the distinct structural dynamics of monolayer crystals from their bulk counterparts. Looking into the future, the recent progress of developing multimodal, multiscale x-ray imaging platform will be discussed to go beyond the ensemble average for studying nanoscale ultrafast dynamics.

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Workshop / Seminar Tue, 25 Feb 2020 18:16:47 -0500 2020-02-25T16:00:00-05:00 2020-02-25T17:00:00-05:00 West Hall Department of Physics Workshop / Seminar West Hall
Department Colloquium | High Energy Physics Under The Higgs Lamppost (February 26, 2020 4:00pm) https://events.umich.edu/event/72100 72100-17939963@events.umich.edu Event Begins: Wednesday, February 26, 2020 4:00pm
Location: West Hall
Organized By: Department of Physics

For the past half a century, high energy physics has achieved uninterrupted successes. With the milestone discovery of the Higgs boson at the CERN Large Hadron Collider (LHC), high energy physics has entered a new era. The completion of the “Standard Model” (SM) implies, for the first time ever, that we have a relativistic, quantum-mechanical, self-consistent theoretical framework, conceivably valid up to exponentially high energies, even to the Planck scale. Yet, the SM leaves many unanswered questions both from the theoretical and observational perspectives, including the nature of the electroweak superconductivity and its phase transition, the hierarchy between the particle masses and between the observed scales, the nature of dark matter etc. There are thus compelling reasons to believe that new physics beyond the SM exits. We argue that the collective efforts of future high energy physics programs, in particular the future colliders, hold great promise to uncover the laws of nature to a deeper level.

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Workshop / Seminar Wed, 26 Feb 2020 18:17:07 -0500 2020-02-26T16:00:00-05:00 2020-02-26T17:00:00-05:00 West Hall Department of Physics Workshop / Seminar West Hall
Astronomy Colloquium Series Presents (February 27, 2020 3:30pm) https://events.umich.edu/event/70221 70221-17549990@events.umich.edu Event Begins: Thursday, February 27, 2020 3:30pm
Location: West Hall
Organized By: Department of Astronomy

“The Next Step in Deep Extragalactic Surveys”

The original rationale for the James Webb Space Telescope was detecting the first light in the Universe, meaning the first stars and galaxies. This goal has remained as one of the key drivers for the hardware development albeit with the footnote that only the first galaxies, not literally the first individual stars, can be detected. Two of the instruments teams, the NIRCam and NIRSpec Teams, have joined forces to produce a legacy survey with both multi-wavelength imaging and multi-object spectroscopy
using JWST. Expected results as illustrated by a mock catalog and a data challenge will be presented.


Please note: Should you require any accommodations to ensure equal access and opportunity related to this event please contact Stacy Tiburzi at 734-764-3440 or stibu@umich.edu.

Tea will be served beforehand from 3:00-3:30pm in Serpens.

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Lecture / Discussion Thu, 23 Jan 2020 13:05:14 -0500 2020-02-27T15:30:00-05:00 2020-02-27T16:30:00-05:00 West Hall Department of Astronomy Lecture / Discussion Dr. Marcia J. Rieke
CM Theory Seminar | Lattice Models and Monte Carlo Solutions for Quantum Criticality (February 27, 2020 4:00pm) https://events.umich.edu/event/72904 72904-18090326@events.umich.edu Event Begins: Thursday, February 27, 2020 4:00pm
Location: West Hall
Organized By: Department of Physics

In this talk, I will review recent developments in a priori and a posteriori numerical strategies in dealing with quantum many-body systems. Thanks to these philosophical and numerical advancements, novel paradigms in condensed matter and high energy physics such as non-Fermi-liquid, quantum criticality and emergent gauge-field coupled with matter field can be readily accessed with large-scale numerical simulations. These results in turn inspire further analytical and numerical progress towards the complete understanding of few important quantum many body physics problems.

References:
1. TOPICAL REVIEW, J. Phys.: Condens. Matter 31, 463001 (2019)
2. PNAS August 20, 2019 116 (34) 16760-16767
3. Phys. Rev. X 9, 021022 (2019)

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Workshop / Seminar Thu, 27 Feb 2020 18:16:59 -0500 2020-02-27T16:00:00-05:00 2020-02-27T17:00:00-05:00 West Hall Department of Physics Workshop / Seminar West Hall
HEP-Astro Seminar | Shedding 'Nu' Light on the Nature of Matter: The Search for Majorana Neutrinos (March 9, 2020 4:00pm) https://events.umich.edu/event/72101 72101-17939964@events.umich.edu Event Begins: Monday, March 9, 2020 4:00pm
Location: West Hall
Organized By: Department of Physics

Why is the universe dominated by matter, and not antimatter? Neutrinos, with their changing flavors and tiny masses, could provide an answer. If the neutrino is a Majorana particle, meaning that it is its own antiparticle, it would reveal the origin of the neutrino’s mass, demonstrate that lepton number is not a conserved symmetry of nature, and provide a path to leptogenesis in the early universe. To discover whether this is the case, we must search for neutrinoless double-beta decay, a theorized process that would occur in some nuclei. By searching for this extremely rare decay, we can explore new physics at energy scales that only existed in the seconds following the Big Bang.

Detecting this extremely rare process, however, requires us to build very large detectors with very low background rates. Experiments using germanium detectors, like the Majorana Demonstrator, which is currently running, and LEGEND-200, which is moving forward quickly, are a promising strategy to explore lifetimes of up to 10^{28} years. The current generation of experiments have achieved the lowest backgrounds of any technique, and have a clear path forward to move to the ton-scale. I’ll present recent results from the Demonstrator, an update on LEGEND-200’s progress, and prospects for LEGEND-1000.

Reaching lifetimes beyond 10^{28} years, however, will require new techniques and kiloton-scale detectors. NuDot is a proof-of-concept liquid scintillator experiment that will explore new techniques for isotope loading and background rejection in future detectors. I’ll discuss the progress we’ve already made in demonstrating how previously-ignored Cherenkov light signals can help us distinguish signal from background, and the technologies we’re developing with an eye towards the coming generations of experiments.

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Workshop / Seminar Mon, 09 Mar 2020 18:16:42 -0400 2020-03-09T16:00:00-04:00 2020-03-09T17:00:00-04:00 West Hall Department of Physics Workshop / Seminar West Hall
CM-AMO Seminar | Double Feature (March 10, 2020 4:00pm) https://events.umich.edu/event/72102 72102-17939965@events.umich.edu Event Begins: Tuesday, March 10, 2020 4:00pm
Location: West Hall
Organized By: Department of Physics

Pfaffian Formalism for Higher-Order Topological Insulators

Higher-order topological insulators (HOTIs) are characterized by gapless modes that occur at lower-dimensional boundaries than the conventional (first-order) topological insulators (TIs). For example, a 3D second-order TI has gapless 1D hinge modes and gapped 2D surface and gapped 3D bulk, whereas a 3D first-order TI has gapless 2D surface modes. In general, n-th order TI in d-dimensional space has gapless modes at (d-n) dimensional boundary.

In this work, we generalize the Pfaffian formalism, which has been playing an important role in the study of time-reversal invariant first-order topological insulators, to 3D chiral higher-order topological insulators protected by the product of four-fold rotational symmetry C_4 and the time-reversal symmetry T. This Pfaffian description reveals a deep and fundamental link between TIs and HOTIs, and allows important conclusions about TIs to be generalized to HOTIs. In particular, we can generalize Fu-Kane's parity criterion for TIs to HOTIs, and also present a general method to efficiently compute the Z_2 index of 3D chiral HOTIs without a global gauge.

Spatially Coherent Lasing in an Atomically-Thin Heterostructure

Atomically thin two-dimensional (2D) semiconductors are a promising gain media for the next generation of semiconductor lasers and nanophotonics. They have advantages over the traditional III-V semiconductors because they exhibit strong light-matter interaction, are flexible and compact, and allow easy integration with various substrates. Utilizing these advantages, we engineer a lasing device with a rotationally aligned WSe2-MoSe2 van der Waals heterostructure integrated with a one-dimensional (1D) silicon nitride (SiN) grating resonator. Angle-resolved micro-photoluminescence and spatial coherence measurements show signatures of lasing, which include bright emission intensity and formation of extended spatial coherence. This work establishes 2D semiconductor heterostructures as a new type of gain medium.

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Workshop / Seminar Mon, 09 Mar 2020 12:48:01 -0400 2020-03-10T16:00:00-04:00 2020-03-10T17:00:00-04:00 West Hall Department of Physics Workshop / Seminar West Hall
Statistics Department Seminar Series: Jimmy de la Torre, Professor, Human Communication, Development, and Information Sciences, University of Hong Kong (March 10, 2020 4:00pm) https://events.umich.edu/event/73305 73305-18190739@events.umich.edu Event Begins: Tuesday, March 10, 2020 4:00pm
Location: West Hall
Organized By: Department of Statistics

Abstract:
At present, many educational researchers and practitioners are highly interested in using educational assessment to improve student learning. However, it should be noted that assessment and learning can exist as two distinct components, and require a framework that would allow their integration into a single coherent system. The efficiency of such a system will depend on the extent that each component can be implemented adaptively. In this presentation, I will discuss using cognitive diagnosis modeling as a framework for developing a personalize assessment and learning system (PALS). I will discuss what cognitive diagnosis models (CDMs) are, what their unique features are, how they differ from other psychometric models, and how cognitive diagnosis computerized adaptive testing can further capitalize on the advantages of CDMs and make diagnostic testing more efficient. To build the complete PALS, an explicit instructional component that can facilitate learning is needed. I will discuss a number of important issues that need to addressed before a coherent and effective PALS can be built. The presentation will conclude with a discussion of possible future directions, and some of the challenges and recent developments in the area.

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Workshop / Seminar Tue, 25 Feb 2020 17:18:51 -0500 2020-03-10T16:00:00-04:00 2020-03-10T17:00:00-04:00 West Hall Department of Statistics Workshop / Seminar Jimmy de la Torre
Department Colloquium | Spins and Photons for Quantum Information Technologies (March 11, 2020 4:00pm) https://events.umich.edu/event/72134 72134-17942180@events.umich.edu Event Begins: Wednesday, March 11, 2020 4:00pm
Location: West Hall
Organized By: Department of Physics

Large scale quantum networks are envisioned for secure quantum communication between any two points on earth and for the creation of various cryptographic protocols. Quantum networks are also a model for distributed quantum computing. Quantum emitters featuring spin-photon interfaces and quantum memories are crucial elements in the nodes of such networks. Non-classical states of light, such as single and entangled photons, are also critical for novel quantum technologies. Key questions are therefore how to control the nodes of these networks and how to produce the desired photonic states. I will give and overview of the field and present our work focusing on the control of spins and the deterministic generation of highly entangled photonic states from spinful quantum emitters such as color centers and semiconductor quantum dots.

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Workshop / Seminar Wed, 11 Mar 2020 18:16:43 -0400 2020-03-11T16:00:00-04:00 2020-03-11T17:00:00-04:00 West Hall Department of Physics Workshop / Seminar West Hall
Canceled: Statistics Department Seminar Series: Daniel Almirall, Research Associate Professor, Survey Research Center, Institute for Social Research and Research Associate Professor of Statistics (by courtesy), University of Michigan (March 13, 2020 10:00am) https://events.umich.edu/event/69920 69920-17483052@events.umich.edu Event Begins: Friday, March 13, 2020 10:00am
Location: West Hall
Organized By: Department of Statistics

"Assessing Proximal Causal Effects on a Binary Outcome using Data from a Micro-randomized Trial: Case Study Design and Analysis"
Abstract

Emerging mobile health interventions aim to provide support whenever and wherever it is needed. This includes the provision of therapeutic support in (near) real time, as well as the provision of prompts that support the engagement of users in the mobile health application. A micro-randomized trial (MRT) is a new trial design that is useful for addressing scientific questions concerning the construction of mobile health applications of this type.  This talk describes the design and analysis of a micro-randomized trial conducted in collaboration with a local digital behavioral health company based in Ann Arbor. The purpose of the MRT was to (i) test the effectiveness of using a “push” prompt to engage users with a smartphone-based mobile health application, and (ii) to estimate whether the effectiveness of the prompt depends on the time at which the prompt is sent, as well as a prespecified set of user characteristics and other contextual factors. The trial’s primary outcome was binary, namely, whether or not the user engaged with the smartphone app over the next 24 hours. To analyze the data arising from this MRT, we developed a new approach to estimating the proximal causal effects that could accommodate a binary outcome. We describe the design of the MRT, the new data analysis method, and the results.
An explicit goal of this talk is to provide a friendly introduction to some of the ideas underlying the design and analysis of MRTs, as opposed to focusing on technical details of the method.

This is joint work with Susan A. Murphy, Inbal Nahum-Shani and Niranjan Bidargarddi.

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Workshop / Seminar Thu, 12 Mar 2020 09:41:05 -0400 2020-03-13T10:00:00-04:00 2020-03-13T11:00:00-04:00 West Hall Department of Statistics Workshop / Seminar Almirall,Daniel
CANCELED Karma Masters: the Personhood of Tumors and their People in Northern Thailand (March 13, 2020 3:00pm) https://events.umich.edu/event/73475 73475-18243514@events.umich.edu Event Begins: Friday, March 13, 2020 3:00pm
Location: West Hall
Organized By: Department of Anthropology

How can one make sense of ethical action when one is partly the other? In contexts of critical illness in Northern Thailand, many consider broken parts of themselves - from tumors to torn nerves to psychotic voices - to be beings returned to exact revenge for past wrongs. Many thus endeavor to treat their parts well, including their tumors. In this talk, I explore the implications of this hybrid personhood for living an ethical life, opening the possibility of ethical interaction, forgiveness, and love without individuality.

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Lecture / Discussion Thu, 12 Mar 2020 11:40:38 -0400 2020-03-13T15:00:00-04:00 2020-03-13T17:00:00-04:00 West Hall Department of Anthropology Lecture / Discussion karma masters
CANCELED: The Michigan Anthropology Colloquia Series: "The Breakup 2.1: The Ten Year Update" (March 27, 2020 3:00pm) https://events.umich.edu/event/68800 68800-17153403@events.umich.edu Event Begins: Friday, March 27, 2020 3:00pm
Location: West Hall
Organized By: Department of Anthropology

"Since 2007-2008, American undergraduates’ media ecology has changed – Facebook no longer looms as large in undergraduates’ daily media use, instead they tend to turn to Snapchat, Twitter, and Instagram more frequently. Yet this, it turns out, is not a difference that makes a difference when people break up with each other. The similarities in people’s breakup practices between 2008 and 2018 reveal that, regardless of what social media is used, American undergraduates turn to media in moments of breakup as ways to manage three complicated aspects of ending a relationship: untangling all the ways in which people signal intertwined lives, deciphering the quotidian unknowable of another person’s mind, and trying to control who knows what when. At the same time, there has been a degree of conventionalization around phatic connections, visible in a new set of terms – ghosting, sliding into DM, leaving someone on read -- and the accompanying increasingly common array of practices. In short, this talk explores what insights about stabilization and media change can one glean from interviewing US undergraduates about their mediated breakup practices every ten years."

The Michigan Anthropology Colloquia Series presents speakers on current topics in the field of anthropology

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Lecture / Discussion Thu, 12 Mar 2020 11:41:23 -0400 2020-03-27T15:00:00-04:00 2020-03-27T17:00:00-04:00 West Hall Department of Anthropology Lecture / Discussion West Hall
CANCELED: The Michigan Anthropology Colloquia Series (April 3, 2020 3:00pm) https://events.umich.edu/event/63228 63228-15595500@events.umich.edu Event Begins: Friday, April 3, 2020 3:00pm
Location: West Hall
Organized By: Department of Anthropology

The Michigan Anthropology Colloquia Series presents speakers on current topics in the field of anthropology

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Lecture / Discussion Thu, 12 Mar 2020 11:49:49 -0400 2020-04-03T15:00:00-04:00 2020-04-03T17:00:00-04:00 West Hall Department of Anthropology Lecture / Discussion West Hall
CANCELED: The Michigan Anthropology Colloquia Series (April 10, 2020 3:00pm) https://events.umich.edu/event/70094 70094-17530442@events.umich.edu Event Begins: Friday, April 10, 2020 3:00pm
Location: West Hall
Organized By: Department of Anthropology

The Michigan Anthropology Colloquia Series presents speakers on current topics in the field of anthropology

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Lecture / Discussion Thu, 12 Mar 2020 11:43:22 -0400 2020-04-10T15:00:00-04:00 2020-04-10T17:00:00-04:00 West Hall Department of Anthropology Lecture / Discussion West Hall