Archives: 2011 | 2012 | 2013 | 2014 | 2015 | 2016 | 2017 | 2018

• Local convergence of an alternating minimization algorithm for learning sparse overcomplete dictionaries (2) - RIT on Applied Harmonic Analysis

  Speaker: Addison Bohannon (UMD) -
  

  When: Mon, October 22, 2018 - 12:00pm
  Where: Kirwan Hall 1310
  
• Mathematical models of the immune system - RIT on Cancer Modeling

  Speaker: Jesse Miltzman (University of Maryland) -
  

  When: Mon, October 22, 2018 - 1:00pm
  Where: Kirwan Hall 1310
  
• Height pairings and torsion points - Algebra-Number Theory

  Speaker: Laura DeMarco (Northwestern University) - https://sites.math.northwestern.edu/~demarco/
  

  When: Mon, October 22, 2018 - 2:00pm
  Where: Kirwan Hall 3206
  

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  Abstract: I will discuss uniformity questions surrounding Unlikely Intersection problems -- the most famous of which is the Manin-Mumford Conjecture (proved by Raynaud, 1983) -- and a new result about elliptic curves and the geometry of their torsion points, joint with Holly Krieger and Hexi Ye. Our results hold over C, the field of complex numbers, but the proofs are carried out first over the field of algebraic numbers (and involve an analysis of certain height functions on P^1).
  
• Statistics of Chaotic Strange Attractors for PDEs - RIT on Applied PDE

  Speaker: Alex Blumenthal (University of Maryland) -
  

  When: Mon, October 22, 2018 - 3:00pm
  Where: Kirwan Hall 1311
  

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  Abstract: http://www.terpconnect.umd.edu/~lvrmr/2018-2019-F/Classes/RIT.shtml
  
• Black-box random number generation with a single quantum device - RIT on Quantum Information

  Speaker: Carl Miller (University of Maryland) - http://www.umiacs.umd.edu/~camiller
  

  When: Mon, October 22, 2018 - 4:00pm
  Where: Atlantic 3100A
  

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  Abstract: Random number generation protocols have been constructed that are strictly "device-independent" -- that is, they make no assumptions about the accuracy of the devices used. Such protocols make use of Bell violation experiments, and their security depends on physical assumptions (such as timing or non-communication). I will discuss a major breakthrough result that removes the need for the finer physical assumptions behind device-independent randomness, and relies instead on a computational hardness assumption. This result shows that, in principle, it is possible for a classical user to generate randomness simply by remote interaction with an untrusted client. The proof relies on the hardness of the Learning With Errors problem (LWE), which is used in postquantum cryptography.
  
  Reference: Z. Brakerski, P. Christiano, U. Mahadev, U. Vazirani, T. Vidick. Certifiable Randomness from a Single Quantum Device. arXiv:1804.00640. (2018)
  
• Modular Curves pt. 2 - Ribet/Stein ch. 6 - Student Algebra-Number Theory

  Speaker: Ensemble () -
  

  When: Tue, October 23, 2018 - 1:00pm
  Where: Kirwan Hall 3206
  
• Preperiodic points of polynomials - Dynamics

  Speaker: Laura DeMarco (Northwestern) - http://www.math.northwestern.edu/~demarco/
  

  When: Tue, October 23, 2018 - 2:00pm
  Where: MTH 0104
  

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  Abstract: I will discuss results about the geometry of the periodic (or pre-periodic) points for rational maps on P^1. In new work with Holly Krieger and Hexi Ye, we give a uniform bound on the number of shared preperiodic points for two distinct complex polynomials of the form f(z) = z^2 + c. The question was inspired by analogous results/questions in arithmetic geometry (and the topic of my Number Theory seminar), and its proof involves p-adic analysis and heights -- combined with features of the Julia sets of the quadratic polynomials.
  
• Mathematical approaches to understand and alter swallowing and gait functions in humans - Norbert Wiener Center

  Speaker: Ervin Sejdic (PITT) -
  

  When: Tue, October 23, 2018 - 2:00pm
  Where: Kirwan Hall 1308
  

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  Abstract: A human body comprises of several physiological systems that carry out specific functions necessary for
  daily living. Traumatic injuries, diseases and aging negatively impact human functions, which can cause a
  decreased quality of life and many other socio-economical and medical issues. Accurate models of
  human functions are needed to propose interventions and treatments that can restore deteriorated
  human functions. Therefore, our research aims to develop novel mathematical approaches that can
  accurately assess changes in swallowing and gait functions by focusing on dynamical interactions
  between musculoskeletal and other physiological systems. In this talk, I will present some of our recent
  contributions dealing with both mathematical and clinical aspects of our work. Lastly, I will also present
  our future research goals and our strategy to achieve these goals.
  
  BIOGRAPHY
  Dr. Ervin Sejdić received B.E.Sc. and Ph.D. degrees in electrical engineering from the University of
  Western Ontario, London, Ontario, Canada in 2002 and 2008, respectively. From 2008 to 2010, he was a
  postdoctoral fellow at the University of Toronto with a cross-appointment at Bloorview Kids Rehab,
  Canada’s largest children’s rehabilitation teaching hospital. From 2010 until 2011, he was a research
  fellow at Harvard Medical School with a cross-appointment at Beth Israel Deaconess Medical Center.
  From his earliest exposure to research, he has been eager to contribute to the advancement of scientific
  knowledge through carefully executed experiments and ground-breaking published work. This has
  resulted in co-authoring over 130 journal publications. In February 2016, President Obama named Dr.
  Sejdić as a recipient of the Presidential Early Career Award for Scientists and Engineers, “…the highest
  honor bestowed by the United States Government on science and engineering professionals in the early
  stages of their independent research careers.” In 2017, Dr. Sejdić was awarded the National Science
  Foundation CAREER Award. In 2018, he was awarded the Chancellor’s Distinguished Research Award at
  the University of Pittsburgh. Dr. Sejdić’s passion for discovery and innovation drives his constant
  endeavors to connect advances in engineering to society’s most challenging problems. Hence, his
  research interests include biomedical signal processing, gait analysis, swallowing difficulties, advanced
  information systems in medicine, rehabilitation engineering, assistive technologies and anticipatory
  medical devices.
  
• Graph Properties for Fraïssé Classes - Logic

  Speaker: Miriam Parnes (Wesleyan University) -
  

  When: Tue, October 23, 2018 - 3:30pm
  Where: Kirwan Hall 1311
  

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  Abstract: The class of all finite graphs is an example of an algebraically trivial Fraïssé class with a particular kind of independence relation. In this talk, I will explain how we can generalize certain concepts and results from graphs to any algebraically trivial Fraïssé class with the same kind of independence relation.
  
• Geometric errors in surface finite element methods - Numerical Analysis

  Speaker: Alan Demlow (Department of Mathematics, Texas A&M University) - http://www.math.tamu.edu/~demlow/
  

  When: Tue, October 23, 2018 - 3:30pm
  Where: Kirwan Hall 3206
  

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  Abstract: Surface finite element methods are commonly used to approximate solutions to the Laplace-Beltrami problem posed on surfaces. These methods generally employ two levels of approximation. One is the Galerkin approximation typical of finite element methods, and the other is a polynomial approximation of the surface on which the PDE is posed. Errors due to the latter approximation are called geometric errors. Geometric errors generally exhibit a consistent order of convergence with respect to the polynomial degree of the approximation in a wide variety of situations. In this talk we will focus on two recently discovered situations in which the geometric error has more subtle behavior. These are eigenvalue problems and a posteriori error estimation. In both of these cases, the particular way in which the discrete surface is constructed or represented in codes affects the order of the geometric error. Time permitting, we may also briefly discuss geometric errors in problems involving vector Laplace-type surface operators, such as the surface Stokes equations.
  
• Statistical Leveraging Methods in Big Data - RIT on Statistics

  Speaker: Mark Wymer (UMCP) -
  

  When: Tue, October 23, 2018 - 4:00pm
  Where: Kirwan Hall 1313
  
• Pluripotential theory and convex bodies - Informal Geometric Analysis

  Speaker: Norman Levenberg (Indiana University) -
  

  When: Tue, October 23, 2018 - 4:30pm
  Where: Kirwan Hall 3206
  

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  Abstract: Given a convex body P one can associate a natural class of plurisubharmonic functions: those that grow like the logarithmic indicator function. These generalizations of Lelong classes in standard pluripotential theory arise in the theory of random sparse polynomials and in problems involving polynomial approximation. We give some examples of extremal plurisubharmonic functions in this setting and discuss other results in the general theory as well as connections with complex geometry.
  
• Isoperimetric Inequalities 2 - RIT on Lifetime Data Science

  Speaker: Yuanhang Wang (UMD) -
  

  When: Tue, October 23, 2018 - 5:00pm
  Where: Kirwan Hall 1308
  
• Cohomology of Tiling Spaces - Student Geometry and Topology

  Speaker: Jianlong Liu (UMD) -
  

  When: Wed, October 24, 2018 - 3:00pm
  Where: Kirwan Hall 1308
  
• A method for numerical computation starting from a quasiperiodic trajectory - Applied Dynamics

  Speaker: Prof. Evelyn Sander - George Mason University Department of Mathematics
  

  When: Thu, October 25, 2018 - 12:30pm
  Where: AVW 1147
  

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  Abstract: A trajectory is quasiperiodic if the trajectory lies on and is dense in some d-dimensional torus, and there is a choice of coordinates on the torus for which F has the form of a rigid rotation on the torus with rotation vector rho. There is an extensive literature on determining the rotation vector associate with F, as well finding Fourier components to establish these conjugacies. I will present two new methods with very good convergence rates: the Weighted Birkhoff Method and the Embedding Continuation Method. They are based on the Takens Embedding Theorem and the Birkhoff Ergodic Theorem. I will illustrate these for one- and two-dimensional examples ideas by computing rotation vectors or numbers, computing Fourier components for conjugacies, and distinguishing chaos versus quasiperiodic behavior.
  
• Simple Low-dimensional Paradigms for higher-dimensional chaos - Dynamics

  Speaker: James Yorke (UMD) - http://www.chaos.umd.edu/~yorke/
  

  When: Thu, October 25, 2018 - 2:00pm
  Where: Kirwan Hall 1311
  

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  Abstract: The most frequently studied dynamical systems are low dimensional and all the periodic orbits in a chaotic set have the same number of unstable dimensions, but this property seems to fail in high dimensional systems.
  
  In this talk I continue this theme. Here we define a property called ``hetero-chaos'', in which, along with the usual properties of chaos, there is a dense set of k-dimensionally unstable periodic orbits, and this holds for more than one k. We provide examples including a piecewise linear generalized baker map. I will explain how to prove ergodicity for our baker-like skew-product maps in 3D. This talk summarizes joint work with Shuddho Das, Yoshi Saiki, Miguel Sanjuan, and Hiroki Takahashi.
  
• A coordinate-free approach to super-Yang-Mills - RIT on Geometry and Physics

  Speaker: Paul Green
  

  When: Thu, October 25, 2018 - 3:30pm
  Where: MTH (Kirwan Hall) 1308
  
• On the construction of unbiased estimators for the group testing problem - Statistics

  Speaker: Dr. Gregory Hader (National Cancer Institute, NIH) -
  

  When: Thu, October 25, 2018 - 3:30pm
  Where: Kirwan Hall 1313
  

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  Abstract:
  
  Abstract
  
  While the use of group testing as a tool for estimation has been on the rise in recent decades, classical problems such as the large bias of the maximum likelihood estimator continue to hinder the implementation of such methods. This has led to the development of many estimators minimizing bias and, most recently, an unbiased estimator based on sequential binomial sampling. Previous research, however, has focused heavily on the simple case where no misclassification is assumed and only one trait is to be tested. In this talk, we consider the problem of unbiased estimation in these broader areas, giving constructions of such estimators for several cases. We show that, outside of the standard case addressed previously in the literature, it is impossible to find any proper unbiased estimator, that is, an estimator giving only values in the parameter space. This is shown to hold generally under any binomial or multinomial sampling plans.
  
  
• PhD Final Oral Exam: Harmonic Analysis and Machine Learning - RIT on Deep Learning

  Speaker: Michael (Pekala) -
  

  When: Fri, October 26, 2018 - 12:00pm
  Where: EGR0108
  
• On traffic modeling and the Braess paradox - Colloquium

  Speaker: Helge Holden (NTNU (Norwegian University of Science and Technology)) - https://www.ntnu.edu/employees/holden
  

  When: Fri, October 26, 2018 - 3:15pm
  Where: Kirwan Hall 3206
  

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  Abstract: We will discuss models for vehicular traffic flow on networks. The models
  include both the Lighthill-Whitham-Richards (LWR) model and Follow-the-Leader (FtL) models.
  The emphasis will be on the Braess paradox in which adding a road to a traffic network
  can make travel times worse for all drivers.
  In addition, we will present a novel proof how FtL models approximate the LWR model in
  case of heavy traffic.
  
  If time permits, we will discuss a novel model for multi-lane traffic.
  
  The work is joint with N.H. Risebro (Oslo) and R. Colombo (Brescia)