Math Calendar

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November 1st, 2009 (08:00am - 06:00pm)

Seminar: Center for Dynamics and Geometry Seminar
Title: Dynamical Systems and Related Topics Workshop
Speaker: Various, Various
Location: MB114

November 2nd, 2009 (04:00pm - 05:00pm)

Seminar: Student Geometric Functional Analysis Seminar
Title: TBA
Speaker: TBA
Location: MB315
Abstract: http://

November 3rd, 2009 (02:30pm - 03:45pm)

Seminar: Logic Seminar
Title: Determinacy of Wadge classes and subsystems of second-order arithmetic
Speaker: Takako Nemoto, JAIST, Japan
Location: MB315

I will discuss determinacy schemata motivated by Wadge hierarchy, which is finer than Borel hierarchy, and the hierarchy of them in second-order arithmetic. I will introduce characterizations of subsystems of second-order arithmetic, not only the Big Five systems, but also relatively minor systems, by determinacy schemata.

November 3rd, 2009 (02:30pm - 03:30pm)

Seminar: GAP Seminar
Title: Commutative Algebraic Methods in Operator Theory
Speaker: Xiang Fang, Kansas State University
Location: MB106

I will show how to introduce commutative algebraic methods to study problems about Hilbert space operators, especially those of a "local" nature, such as the Fredholm index. Examples include how to calculate Fredholm index using Samuel multiplicity, a fundamental local invariant of algebraic varieties. The talk is accessible to graduate students.

November 3rd, 2009 (03:30pm - 06:00pm)

Seminar: Working Seminar: Dynamics and its Working Tools
Title: Measure rigidity for Zariski dense groups, III.
Speaker: Jean-Francois Quint, University of Paris-13
Location: MB216
Abstract: http://www.math.psu.edu/katok_a/Quint-lectures.pdf

November 4th, 2009 (03:30pm - 04:00pm)

Seminar: Center for Dynamics and Geometry Seminar
Title: Elementary surprises in projective geometry
Speaker: S. Tabachnikov, Penn State
Location: MB106

Jointly with R. Schwartz, we have recently discovered eight new (?) configuration theorems of projective geometry, somewhat similar to the classical Pappus and Pascal theorems. These theorems involve n-gons with n from six to twelve. I shall describe these results and illustrate them by computer graphics. I shalll explain how they originated in our study of the pentagram map, a completely integrable system on the moduli space of polygons in the projective plane.

November 5th, 2009 (11:00am - 12:30pm)

Seminar: Teaching Seminar
Title: MASS and Problem Solving
Speaker: Sergei Tabachnikov
Location: MB114

Sergei will speak about the MASS program and will give examples of the Problem Solving that takes place in this program.

November 5th, 2009 (11:15am - 12:05pm)

Seminar: Algebra and Number Theory Seminar
Title: Uniform boundedness in arithmetic dynamics
Speaker: Abrus Pal, Imperial College, London
Location: MB106

November 5th, 2009 (02:30pm - 03:30pm)

Seminar: Noncommutative Geometry Seminar
Title: C*-Algebras, Foliations and K-Theory 4
Speaker: Allan Yashinski, Penn State
Location: MB106
Abstract: http://www.math.psu.edu/roe/NCG/notes-index.html

November 5th, 2009 (02:30pm - 03:20pm)

Seminar: MASS Colloquium
Title: Everything you wanted to know about 2x2 matrices
Speaker: Svetlana Katok, Penn State
Location: MB113

The group SL(2,R) is at the junction of number theory, representation theory, topology, geometry and dynamics. This seemingly simple object is both a source of deep questions and a proving ground for a variety of methods. We will reveal some surprising connections between arithmetic, geometry and dynamics that arise from the study of this interesting group.

November 6th, 2009 (12:00pm - 01:30pm)

Seminar: CCMA Luncheon Seminar
Title: Concurrent atomistic-continuum coupling via a spacetime discontinuous Galerkin method
Speaker: Scott Miller, Applied Research Laboratory, Penn State
Location: MB114

In an expanding class of applications, accurate simulations across multiple spatial and temporal scales is necessary for design and analysis purposes. We investigate an atomistic-to-continuum (AtC) concurrent coupling method to couple our h-adaptive spacetime discontinuous Galerkin (SDG) for continuum elastodynamics to an atomistic discontinuous Galerkin (ADG) method for particle dynamics. The formulation couples non-overlapping continuum and atomistic models across a sharp interface in a mathematically consistent fashion. We show that the AtC method is able to pass mechanical signals across the material interface without damping or energy loss. Numerical examples also demonstrate the ability of the h-adaptive SDG method to reconcile disparate time steps while resolving the atomistic signal in the continuum.

November 6th, 2009 (03:35pm - 04:25pm)

Seminar: Computational and Applied Mathematics Colloquium
Title: An overview of spacetime discontinuous Galerkin methods
Speaker: Scott Miller, Applied Research Laboratory, Penn State
Location: MB106

Discontinuous Galerkin methods are a family of finite element methods that utilize non-conforming solution spaces; that is, continuity is not enforced a priori through the choice of finite dimensional solution space. Instead, the governing equations and initial/boundary conditions are weakly enforced on an element-by-element basis. Spacetime discontinuous Galerkin (SDG) methods directly discretize space and time as a single entity, removing the need for separate temporal integration schemes. SDG methods possess many attractive features, including: high order convergence rates, fixed compact stencil for arbitrary interpolation order, support for fully unstructured and non-conforming meshes, and excellent stability and element-wise conservation properties. For strictly hyperbolic problems, a special mesh generation procedure may be used to solve small patches of elements independently from the remainder of the domain, resulting in a solution procedure with linear computational complexity. SDG methods are a natural choice for transient simulations of dynamic, non-smooth, and complex physics. In this work, we apply the SDG method to several different physical systems: linear elastodynamics, inviscid gas dynamics, hyperbolic heat conduction, and atomistic-to-continuum coupling. These examples will demonstrate the robustness of SDG for multi-scale and multi-physics applications, including fully non-linear models and sharp interfaces.

November 9th, 2009 (02:30pm - 03:30pm)

Seminar: The Pritchard Lab Seminar
Title: TBA
Speaker: Bernard Deconinck, Dept of Applied Mathematics, University of Washington
Location: MB216

November 9th, 2009 (03:30pm - 05:30pm)

Seminar: Center for Dynamics and Geometry Seminar
Title: An overview of principal results and open problems in parabolic dynamics
Speaker: Anatole Katok, Penn State
Location: MB106
Abstract: http://www.math.psu.edu/katok_a/Parabolic-anno.pdf

November 9th, 2009 (04:00pm - 05:00pm)

Seminar: Student Geometric Functional Analysis Seminar
Title: TBA
Speaker: TBA
Location: MB315
Abstract: http://

November 10th, 2009 (02:30pm - 03:45pm)

Seminar: Logic Seminar
Title: LR-reducibility and the Turing jump operator
Speaker: Stephen G. Simpson, Pennsylvania State University
Location: MB315
Abstract: http://www.math.psu.edu/simpson/papers/massmtr.pdf

For any recursive ordinal alpha, let 0^(alpha) denote the alpha-th Turing jump of 0. We prove that if 0^(alpha) is LR-reducible to a Turing oracle X then 0^(alpha+1) is Turing reducible to the Turing jump of X. We then apply this result to the study of measure-theoretic regularity in the effective Borel hierarchy. In particular, 0^(alpha) is LR-reducible to X if and only if every set at level alpha+2 of the effective Borel hierarchy includes a set of the same measure which is an effective union of effectively closed sets relative to X.

November 10th, 2009 (02:30pm - 03:30pm)

Seminar: GAP Seminar
Title: Singularities of admissible normal functions
Speaker: Zhaohu Nie, PSU-Altoona
Location: MB106

The first proof of the Lefschetz (1,1) theorem was given by Poincare and Lefschetz using normal functions for a Lefschetz pencil. The hope to generalize this method to higher codimensional Hodge conjecture was blocked by the failure of Jacobian inversion. In another direction, one can hope for an inductive proof of the Hodge conjecture if for any primitive Hodge class one can find a, necessarily singular, hypersurface to "capture part of it". Recently Green and Griffiths introduced the notion of extended normal functions over higher dimensional bases such that their singular loci corresponds to such hypersurfaces. In this talk, we will present how to understand singularities using the viewpoint of admissible normal functions, and how the Hodge conjecture is then equivalent to the existence of singularities. This is joint work with P. Brosnan, H. Fang and G. Pearlstein.

November 10th, 2009 (03:30pm - 06:00pm)

Seminar: Working Seminar: Dynamics and its Working Tools
Title: Measure rigidity for Zariski dense groups, IV.
Speaker: Jean-Francois Quint, University of Paris-13
Location: MB216
Abstract: http://www.math.psu.edu/katok_a/Quint-lectures.pdf

November 11th, 2009 (12:15pm - 01:15pm)

Seminar: Geometry Luncheon Seminar
Title: Curvature and the sign of the Euler characteristic
Speaker: John Roe, Penn State
Location: MB114

A conjecture variously attributed to Hopf or Chern says that the Euler characteristic of a compact 2n-dimensional, nonpositively curved manifold should have sign (-1)^n. In dimension 2 this follows from the classical Gauss-Bonnet theorem and in dimension 4 from Chern's generalization, but in dimensions 6 and up local computations do not suffice for the proof. I'll talk about the analytic methods that go back to the work of Atiyah and Dodziuk in the 1970s, and especially about Gromov's beautiful proof that the theorem is true for a negatively curved Kahler manifold.

November 12th, 2009 (11:15am - 12:05pm)

Seminar: Algebra and Number Theory Seminar
Title: A Dirichlet Unit Theorem for Drinfeld modules
Speaker: Lenny Taelman, University of Leiden
Location: MB106

November 12th, 2009 (02:30pm - 03:30pm)

Seminar: Noncommutative Geometry Seminar
Title: C*-Algebras, Foliations and K-Theory 5
Speaker: Yi-Jun Yao
Location: MB106
Abstract: http://www.math.psu.edu/roe/NCG/notes-index.html

November 12th, 2009 (02:30pm - 03:30pm)

Seminar: MASS Colloquium
Title: Topological Network Topology
Speaker: Robert Ghrist, University of Pennsylvania
Location: MB114
Abstract: http://

Networks are ubiquitous: communications networks, social networks, sensor networks, biological networks, etc., abound. "Network topology" is, usually, a misnomer, connoting graph theory. This talk will, via simple examples, argue for a topological interpretation of networks that, via algebraic topology, reveals classes of information hidden within networks around us.

November 12th, 2009 (02:30pm - 03:20pm)

Seminar: MASS Colloquium
Title: Topological Network Topology
Speaker: Robert Ghrist, University of Pennsylvania
Location: MB113

Networks are ubiquitous: communications networks, social networks, sensor networks, biological networks, etc., abound. "Network topology" is, usually, a misnomer, connoting graph theory. This talk will, via simple examples, argue for a topological interpretation of networks that, via algebraic topology, reveals classes of information hidden within networks around us.

November 12th, 2009 (04:00pm - 05:00pm)

Seminar: Department of Mathematics Colloquium
Title: Euler Integration for Data
Speaker: Robert Ghrist, University of Pennsylvania
Location: MB114

This talk covers an ingenious integral calculus based on Euler characteristic, stemming from work on sheaves due to MacPherson and Kashiwara in the 1970s, and connecting back further to classical integral geometry. I will emphasize its novel utility in data management, particularly in aggregation of redundant data and inverse problems over sensor networks. As often happens, applying these tools to practical problems suggests a new generalization of this calculus with deep connections to Morse theory.

November 13th, 2009 (12:00pm - 01:30pm)

Seminar: CCMA Luncheon Seminar
Title: Introduction to Mathematical Modeling of Cellular Signaling in Macrophages
Speaker: Mary Ann Horn, NSF and Department of Mathematics, Vanderbilt University
Location: MB114

This will be an introduction for the colloquium talk held later in the afternoon.

November 13th, 2009 (03:35pm - 04:25pm)

Seminar: Computational and Applied Mathematics Colloquium
Title: Mathematical Modeling of Cellular Signaling in Macrophages: Understanding the Pathways
Speaker: Mary Ann Horn, NSF and Department of Mathematics, Vanderbilt University
Location: MB106

Our goal is the construction of a comprehensive mathematical model for the uridine 5'-diphosphate (UDP) signaling pathway in the RAW 264.7 macrophage, a type of white blood cell. This mathematical model incorporates modules for: (i) the ligand interaction with the P2Y6 receptor, the putative mode of action for UDP; (ii) the subsequent G-protein cascade; (iii) the activation of effector enzymes including phospholipase C (PLC), diacylglycerol kinase (DGK), and several forms of phosphatidylinositol kinase (PI4K, PI5K). In addition, small molecule dynamics for Ca2+, IP3, and PIPn are either modeled or used as functional inputs to provide a comprehensive description of the signaling dynamics. Our model focuses on diacylglycerol (DAG) and phosphatidic acid (PA), and lipidomic technology is utilized to measure the formation and fate of these important lipid second messengers. Modeling techniques, challenges, and computational simulations will be presented. (Joint work with Hannah L. Callender, Dianne L. DeCamp, Paul C. Sternweis, and H. Alex Brown.)

November 16th, 2009 (03:30pm - 05:30pm)

Seminar: Center for Dynamics and Geometry Seminar
Title: Effective results on actions of commuting toral automorphisms
Speaker: Zhiren Wang, Princeton
Location: MB106

Let $G$ be an abelian subgroup of $SL(d,Z)$. When $G$ acts totally irreducibly on $T^d$, has some hyperbolicity and is not virtually-cyclic, Berend proved that every orbit on $T^d$ is either the whole torus or finite. We will discuss effective forms of this theorem and how they are related to number-theoretical problems. This is an analogue of the recent quantitative Furstenberg's theorem concerning the $\times 2$, $\times 3$ action on the circle by Bourgain-Lindenstrauss-Michel-Venkatesh.

November 16th, 2009 (03:35pm - 04:25pm)

Seminar: CCMA PDEs and Numerical Methods Seminar Series
Title: TBA
Speaker: Arash Yavari, The School of Civil and Environmental Engineering, Georgia Tech
Location: MB216

TBA

November 16th, 2009 (04:00pm - 05:00pm)

Seminar: Student Geometric Functional Analysis Seminar
Title: TBA
Speaker: TBA
Location: MB315
Abstract: http://

November 17th, 2009 (02:30pm - 03:45pm)

Seminar: Logic Seminar
Title: To be announced
Speaker: Kostas Hatzikiriakou, University of Thessaly, Greece
Location: MB315

Abstract not yet available.

November 17th, 2009 (02:30pm - 03:30pm)

Seminar: GAP Seminar
Title: Sheaf of Modules over $F_1$-schemes
Speaker: Chenghao Chu, Johns Hopkins University
Location: MB106

Using Connes and Consani’s definition of F1 -schemes, we define and study the category of coherent sheaves over an F1 -scheme. We show that exact sequences of locally free modules are well defined in the category of coherent sheaves over an F1 -scheme. We then apply Q-construction to define algebraic K-theory of F1 -schemes. In partic- ular, we show that the algebraic K-groups of S pec(F1 ) are the stable homotopy groups of the sphere $S^0$ , which is generally believed to be true. If time permits, we define algebraic K-theory of not necessarily commutative monoids. In particular, we discuss the homotopy invari- ance property of algebraic K-theory of monoids and F1 -schemes.

November 17th, 2009 (03:30pm - 06:00pm)

Seminar: Working Seminar: Dynamics and its Working Tools
Title: Survey of Arnold diffusion
Speaker: Vadim Kaloshin, Penn State
Location: MB216

November 17th, 2009 (04:00pm - 04:55pm)

Seminar: Applied Analysis Seminar
Title: Differential games with imperfect information.
Speaker: Pierre Cardialiaguet, University of Brest, France
Location: MB106

after recalling some basic results on zero-sum differential games with perfect information (dynamic programming, existence and characterization of the value in terms of viscosity solution of some Hamilton-Jacobi equation), I will briefly introduce and discuss the model of differential games with imperfect information, where the players have an asymmetric information on the data.

November 18th, 2009 (12:15pm - 01:15pm)

Seminar: Geometry Luncheon Seminar
Title: Closed geodesics in Riemannian and Finsler manifolds
Speaker: Anatole Katok, PSU
Location: MB114

November 19th, 2009 (11:00am - 12:30pm)

Seminar: Teaching Seminar
Title: Math and the Library
Speaker: John Meier
Location: MB114

The Physical and Mathematical Sciences Library provides a number of services to students and instructors such as course reserves and interlibrary loan. Along with a brief review of these services, John Meier, the math librarian, will discuss how the discovery of books and information in the library can get students excited about mathematics."

November 19th, 2009 (02:30pm - 03:30pm)

Seminar: Noncommutative Geometry Seminar
Title: C*-Algebras, Foliations and K-Theory 6
Speaker: Yanli Song, Penn State
Location: MB106
Abstract: http://www.math.psu.edu/roe/NCG/notes-index.html

November 19th, 2009 (04:00pm - 05:00pm)

Seminar: Department of Mathematics Colloquium
Title: Second species solutions of the 3 body problem
Speaker: S. Bolotin, University of Wisconsin and Moscow Steklov Mathematical Institute
Location: MB114

Most of Poincare's work on Celestial Mechanics is about 3 body problem with two of the masses small, e.g. Sun and two planets. He named periodic orbits which encounter near collisions of small masses second species solutions. Such solutions shadow chains of collision orbits of two uncoupled Kepler problems. Levi-Civita regularization replaces double collisions of small masses by a 2-dimensional normally hyperbolic symplectic invariant manifold. Then description of almost collision orbits is reduced to dynamics of a skew product of a collection of symplectic maps defined in terms of the Kepler problem. We will see that in many cases this dynamics can be analyzed.

November 20th, 2009 (03:35pm - 04:25pm)

Seminar: Computational and Applied Mathematics Colloquium
Title: TBA
Speaker: Mitchell Luskin, School of Mathematics, University of Minnesota
Location: MB106

November 20th, 2009 (04:00pm - 10:00pm)

Seminar: Center for Undergraduate Research in Mathematics
Title: Conference for Undergraduate Research in Mathematics
Speaker: Various, Various
Location: MB114

November 21st, 2009 (07:00am - 07:00pm)

Seminar: Center for Undergraduate Research in Mathematics
Title: Conference for Undergraduate Research in Mathematics
Speaker: Various, Various
Location: MB114

November 23rd, 2009 (04:00pm - 05:00pm)

Seminar: Student Geometric Functional Analysis Seminar
Title: TBA
Speaker: TBA
Location: MB315
Abstract: http://

November 26th, 2009 (11:15am - 12:05pm)

Seminar: Algebra and Number Theory Seminar
Title: Thanksgiving
Speaker: Mr Turkey
Location: MB106

November 27th, 2009 (03:35pm - 04:25pm)

Seminar: Computational and Applied Mathematics Colloquium
Title: Thanksgiving break
Speaker: No talk
Location: MB106

November 30th, 2009 (02:30pm - 03:30pm)

Seminar: The Pritchard Lab Seminar
Title: Gravity waves from vortex dipoles and jets
Speaker: Fuqing Zhang, Dept of Meteorology, Penn State University
Location: MB216

Jets are one of the major sources of gravity waves fundamental to atmospheric dynamics. In this study, idealized balanced jets and vortex dipoles in a uniformly stratified atmosphere are used to initialize a nonlinear mesoscale numerical model. In all cases, inertial gravity waves are generated in the jet exit region. We subsequently develop a linear numerical model to explore the source mechanisms of these waves.

November 30th, 2009 (04:00pm - 05:00pm)

Seminar: Student Geometric Functional Analysis Seminar
Title: TBA
Speaker: TBA
Location: MB315
Abstract: http://