The Mathematics Calendar
http://www.math.psu.edu/seminars/calendar.php
Seminars and special events the Pennsylvania State University Mathematics Department2015-11-28webmaster@math.psu.eduA discrete-time approach to stochastic model reduction for the Kuramoto-Sivashinsky PDE
http://www.math.psu.edu/seminars/meeting.php?id=27328
Speaker(s): Kevin Lin
In computational modeling of complex dynamical phenomena, it
is often useful to be able to construct simpler, reduced
models that nevertheless capture key dynamical features of
interest. One well-studied strategy is to fit parametric
families of stochastic models to data. In recent work,
Chorin and Lu proposed a novel, discrete-time approach that
has certain appealing features. I will report on an
application of this discrete-time approach to the
Kuramoto-Sivashinsky PDE, a prototypical model of
spatiotemporal chaos, and discuss some of the issues that
arise and how they can be overcome. This is joint work with
Alexandre Chorin and Fei Lu.2015-11-30T12:20:00CCMA Luncheon Seminarxli@math.psu.edusaz11@math.psu.edumsm37@math.psu.eduliu@math.psu.edushaffer@math.psu.eduAn analysis of implicit sampling in the small-noise limit
http://www.math.psu.edu/seminars/meeting.php?id=27329
Speaker(s): Kevin Lin
Weighted direct samplers, also known as importance samplers,
are Monte Carlo algorithms for generating independent,
weighted samples from a given target probability
distribution. Such algorithms have a variety of
applications in, e.g., data assimilation and state
estimation problems involving stochastic and chaotic
dynamics. One challenge in designing and implementing
weighted samplers is to ensure the variance of the weights,
and that of the resulting estimator, are well-behaved. In
recent work, Chorin, Tu, Morzfeld, and coworkers have
introduced a class of novel weighted samplers called implicit
samplers, which have been shown to possess a number of nice
properties. In this talk, I will report on an analysis of
the variance of implicit samplers in the small-noise limit,
and describe a simple method (suggested by the analysis) to
obtain higher-order implicit samplers. The algorithms are
compared concrete test problems. This is joint work with
Jonathan Goodman and Matthias Morzfeld.2015-11-30T14:30:00Computational and Applied Mathematics Colloquiumxli@math.psu.edusaz11@math.psu.edushaffer@math.psu.eduliu@math.psu.edufuw7@math.psu.eduCutting sequences and dual relationships for Bouw-Möller surfaces
http://www.math.psu.edu/seminars/meeting.php?id=27221
Speaker(s): Diana Davis
Bouw-Möller surfaces are flat surfaces made of polygons. Each one has an associated directed graph, called a "transition diagram," that says something about how a geodesic can cut across its edges. These transition diagrams have a beautiful structure, which comes from a "dual" property relating pairs of surfaces. I will show how this works, with lots of pictures. (Joint work with Corinna Ulcigrai and Irene Pasquinelli)2015-11-30T15:35:00Dynamical systems seminarkatok_s@math.psu.edukatok_a@math.psu.edusaz11@math.psu.eduhertz@math.psu.eduModeling HIV latency reversing agents and its implications for clinical trial design
http://www.math.psu.edu/seminars/meeting.php?id=27477
Speaker(s): Ruian Ke
A major barrier to cure HIV infection is the existence of a population of long lived latently infected cells, i.e. the HIV latent reservoir. Recent efforts have focused on developing latency reversing agents (LRAs) to activate HIV expression in latently infected cells in order to purge the HIV latent reservoir. However, it is not clear to what extent LRAs impact the latency reversing process and which steps in the process determine the rate of reservoir reduction. Furthermore, accurately measuring the size of the reservoir experimentally has been challenging. All these issues make evaluating the efficacy of candidate LRAs and predicting treatment outcomes difficult. To address these issues, we developed a series of mathematical models to describe the dynamics of latently infected cells under LRA treatment. In the first part of the talk, I will present our work on understanding the impact of one of the first LRAs, vorinostat. By fitting viral dynamic models to clinical data, we show that vorinostat induces both transient and delayed HIV transcriptional activation in vivo . However, killing of latently infected cells in treated patients is minimal. In the second part of the talk, I will discuss a stochastic model that incorporates both HIV activation process in vivo and clinical sampling procedures in a probabilistic framework. We identify key parameters that determine the rate of latent reservoir reduction, and using information theory, we evaluate the accuracy in estimating these parameters using data collected from three commonly used experimental assays. To conclude, this framework provides a useful tool for designing future clinical trials and experiments to evaluate the efficacy of candidate LRAs and predict long-term treatment outcomes.2015-12-01T13:30:00Theoretical Biology Seminarcpc16@math.psu.edutreluga@math.psu.eduAlgebraic Families of Harish-Chandra pairs and their modules II
http://www.math.psu.edu/seminars/meeting.php?id=27067
Speaker(s): Eyal Subag
In my talk I will try to convince you that Lie groups come in natural algebraic families. A construction of such families that relates different real forms of GL(n,C), and SL(n,C) will be given. Moreover, we shall see that we can naturally associate families of Harish-Chandra pairs to these families of groups. For the family that goes through SU(2), SU(1,1), and their Cartan motion group, a classification of generically irreducible Harish Chandra modules will be given. As an application, a formulation of the Mackey bijection between the duals of SU(1,1) and its Cartan motion group in terms of families of Harish Chandra modules will be presented. The talk is based on a joint work with Joseph Bernstein and Nigel Higson.2015-12-01T14:30:00GAP Seminareus25@math.psu.edustienon@math.psu.eduping@math.psu.eduhigson@math.psu.eduHausdorff Dimension, Irrationality Exponents and Their Effectivization
http://www.math.psu.edu/seminars/meeting.php?id=27068
Speaker(s): Jan Reimann
We generalize the classical theorem by Jarnik and Besicovitch on the irrationality exponents of real numbers and Hausdorff dimension. Let a be any real number greater than or equal to 2 and let b be any non-negative real less than or equal to 2/a. We show that there is a Cantor-like set with Hausdorff dimension equal to b such that, with respect to its uniform measure, almost all real numbers have irrationality exponent equal to a. We give an analogous result relating the irrationality exponent and the Hausdorff dimension of individual real numbers. We prove that there is a Cantor-like set such that, with respect to its uniform measure, almost all reals in the set have effective Hausdorff dimension equal to b and irrationality exponent equal to a.
This is joint work with V. Becher and T. Slaman.2015-12-01T14:30:00Logic Seminarreimann@math.psu.edujmr71@math.psu.edusimpson@math.psu.eduNon hyperbolic dynamics and non-hyperbolic measures.
http://www.math.psu.edu/seminars/meeting.php?id=27205
Speaker(s): Christian Bonatti
Hyperbolicity provides a simple understanding of chaotic dynamics. In some sense, hyperbolic dynamics are the most complicated dynamics for which one can give a complete topological description. An even more precise description of the dynamics of hyperbolic systems can be obtained through ergodic theory.
However, hyperbolic systems are far from being all chaotic systems: there are numerous robustly non-hyperbolic systems.
I will review several results and mechanisms showing that the existence of non-hyperbolic measures can be robust. In fact, the robust existence of non hyperbolic measure may be the most common situation in the non-hyperbolic world.
I will review several results and mechanisms showing that the existence of non-hyperbolic measures can be robust. In fact, the robust existence of non hyperbolic measure may be the most common situation in the non-hyperbolic world.2015-12-01T14:30:00Center for Dynamics and Geometry Colloquiumkatok_a@math.psu.edusaz11@math.psu.edukatok_s@math.psu.eduhertz@math.psu.eduPartially hyperbolic diffeomorphisms of 3 manifolds I. ATTENTION: THIS TALK WILL START AT 3:45pm
http://www.math.psu.edu/seminars/meeting.php?id=27173
Speaker(s): Christian Bonatti
For decades, the only known examples of partially hyperbolic diffeoomorphisms on 3-manifolds were "center-leaf conjugated", up to taking lift to finite covers and finite powers, to three simple models:
-- time one map of Anosov flows
-- Anosov diffeomorphisms on T3 with 3 real distinct eigenvalues
-- a skew product of an Anosov diffeomorphism of T2 by circle diffeomorphism.
Recently many new examples appear, still very related with the models but not isotopic to them:
-- (non transitive) partially hyperbolic diffeomorphisms on T3 whose center bundle is robustly not tangent to any foliation.
-- (transitive and not transitive) partially hyperbolic diffeomorphisms on manifolds supporting an Anosov flow, which are not isotopic to identity.
I will present these new examples. The first of them is already written and it opened the door to building many more: I will also present many examples that are still work in progress.2015-12-01T15:30:00Working Seminar: Dynamics and its Working Toolskatok_a@math.psu.edusaz11@math.psu.edukatok_s@math.psu.eduhertz@math.psu.edukalinin@math.psu.eduTBA
http://www.math.psu.edu/seminars/meeting.php?id=29014
Speaker(s): Carina Curto
2015-12-02T12:00:00Geometry Luncheon Seminarburago@math.psu.eduroe@math.psu.eduklg5283@math.psu.eduConvolution algebras and group representations I
http://www.math.psu.edu/seminars/meeting.php?id=27132
Speaker(s): Nigel Higson
2015-12-03T14:30:00Noncommutative Geometry Seminarroe@math.psu.eduhigson@math.psu.edusaz11@math.psu.eduFaculty Meeting
http://www.math.psu.edu/seminars/meeting.php?id=25698
Speaker(s): Faculty Meeting
2015-12-03T15:35:00Department of Mathematics Colloquiumsaz11@math.psu.eduliu@math.psu.eduauh243@math.psu.edu