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<>January 2015  




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A live feed of seminars and special events in the upcoming week.
 January 12th, 2015 (12:20pm  01:30pm)
 Seminar: CCMA Luncheon Seminar
Title: Computational Methods for Flows in Porous Media
Speaker: Workshop (8:30am2:30pm)
Location: MB114
Abstract: http://sites.psu.edu/porous2015/The workshop aims to promote scientific interactions on on computational methods for flows in porous media between graduate students from Penn State, the University of Bergen, Technische Universiteit Eindhoven, and the University of Stuttgart visiting the Department of Mathematics at Penn State. All presentations are given by graduate students from these institutions.
 January 12th, 2015 (02:30pm  03:30pm)
 Seminar: Computational and Applied Mathematics Colloquium
Title: Geological Storage of CO2: Modeling approaches for largescale simulation
Speaker: Jan Nordbotten, University of Bergen (Host: L. Zikatanov)
Location: MB106We discuss the challenges of largescale simulation for CO2 storage. In particular, we will emphasize some of the fundamental challenges associated with the scale of the problem, and illustrate their impact on traditional numerical simulation techniques. Furthermore, we will discuss how multiscale formalism can be exploited to yield largescale models of conceptual and practical interest.
 January 12th, 2015 (03:35pm  04:35pm)
 Seminar: Dynamical systems seminar
Title: Transfer operators, Dolgopyat operators, expander graphs, and applications
Speaker: Dale Winter, Brown University
Location: MB114Spectral bounds on transfer operators have consequences in many areas of mathematics, including dynamics, number theory, and lattice counting problems. Two of the standard tools for proving such spectral bounds are the Dolgopyat operator technique and the expander graph approach of BourgainGamburdSarnak. By combining these techniques we can obtain stronger spectral data and correspondingly stronger consequences. I’ll outline some examples of this approach and some of the corresponding applications in number theory and dynamics.
 January 13th, 2015 (01:00pm  02:00pm)
 Seminar: Theoretical Biology Seminar
Title: TBA
Speaker: TBA
Location: MB106  January 13th, 2015 (03:30pm  06:00pm)
 Seminar: Working Seminar: Dynamics and its Working Tools
Title: Multifractal analysis for multiple mixing, I
Speaker: Joerg Schmeling, University of Lund
Location: MB216  January 14th, 2015 (03:30pm  05:30pm)
 Seminar: Applied Algebra and Network Theory Seminar
Title: Abstract Structures in the Design and Analysis of Quantum Algorithms
Speaker: William Zeng, Oxford University
Location: MB315Despite almost two decades of research, there is still a need to find new and useful quantum algorithms. This is of interest in cases where the usefulness ranges from ``able to generate experimental evidence against the extended ChurchTuring thesis" to ``commercially viable". Better languages, frameworks, and techniques for analyzing the structure of quantum algorithms will aid in these attempts. One such programme, initiated by Abramsky, Coecke, et. al, abstracts the setting of quantum information away from Hilbert spaces and linear maps into abstract process theories: dagger symmetric monoidal categories. This talk will have three goals: [0] Introduce how this abstract semantics applies to quantum computation [1] Show how this abstract setting has been used to design and analyze quantum algorithms in the traditional setting of finite Hilbert spaces and linear maps [2] Describe some current work that uses this framework to construct a model of quantum algorithms in the category of relations. See: W. J. Zeng. Models of quantum algorithms in sets and relations: (in preparation), W. J. Zeng & Jamie Vicary. Abstract structure of unitary oracles for quantum algorithms: arxiv.org/abs/1406.1278, Jamie Vicary. The Topology of of Quantum Algorithms: arxiv.org/abs/1209.3917
 January 15th, 2015 (11:15am  12:05pm)
 Seminar: Algebra and Number Theory Seminar
Title: The ErdosHeilbronn Problem for Finite Groups
Speaker: Jeffrey Paul Wheeler, University of Pittsburgh
Location: MB106Additive Number Theory can be best described as the study of sums of sets of integers. A simple example is given two subsets A and B of a set of integers, what facts can we determine about A+B where A+B := { a+b  a \in A andb \in B }? Note that Lagrange's Four Square Theorem can be expressed as N_0 = S + S + S + S where N_0 is the set of nonnegative integers and S the set of all perfect squares. As well the binary version of Goldbach's Conjecture can stated E \subseteq P + P where E be the set of even integers greater than 2 and P the primes, A classic problem in Additive Number Theory was a conjecture of Paul Erdos and Hans Heilbronn which stood as an open problem for over 30 years until proved in 1994 by Dias da Silva and Hamidounne. The conjecture had its roots in the CauchyDavenport Theorem, namely if A and B are nonempty subsets of Z/pZ with p prime, then A+B >= min{p,A+B1\}, where A+B := {a+b  a \in A and b \in B}. Erdos and Heilbronn conjecture in the early 1960s that if the operation is changed to a restricted sum A \dot{+} B := {a+b  a \in A and b \in B, a \ne b}, then A \dot{+} B >= min{p,A+B3\}. We extend these results from Z/pZ to finite groups.
 January 15th, 2015 (03:30pm  04:20pm)
 Seminar: Department of Mathematics Colloquium
Title: Homogenization and Anomalous Diffusion
Speaker: Gautam Iyer, Carnegie Mellon (Host: Alexei Novikov)
Location: MB114Homogenization is a well known technique used to approximate the macroscopic behaviour of a material with microscopic impurities. While this originally arose in the study of composite materials, it has applications to various other fields, and I will focus on a few results motivated by fluid dynamics. One well known result in this direction is that of GI Taylor concerning fluid flows in pipes. Unfortunately the length scales involved in typical oil pipelines are not too short this result to apply. I will conclude by describing joint work with A. Novikov concerning cellular flows (i.e. strong array of opposing vortices) and a conjecture on the effective behaviour in a regime outside that of standard homogenization results.
 January 20th, 2015 (01:00pm  02:00pm)
 Seminar: Theoretical Biology Seminar
Title: Identification and control of the dynamical repertoire of intracellular networks
Speaker: Jorge Gómez Tejeda Zañudo, PSU
Location: MB106An important challenge when modeling intracellular networks is to relate the network structure and function to its stable patterns of activity (attractors). Here we present an approach that can be efficiently applied to large network sizes (up to size 1000 and possibly beyond). Formulated in a discrete dynamic framework, this method is based on a topological criterion to find network motifs that stabilize in a fixed state. Combining these network motifs with network reduction techniques, our method predicts the dynamical repertoire of the network elements (fixed states or oscillations) in the model's attractors, and has also been shown to find all of the model's attractors. To illustrate the applicability of our method, we apply it to two different intracellular network models: the network involved in a type of T cell cancer (T cell large granular lymphocytic leukemia), and the network involved in the metastasis of a type of liver cancer (hepatocellular carcinoma). Interestingly, we find that the network motifs identified during our reduction method play a significant role in the cell fate decision mechanisms in both systems, and also provide insights into how to control the dynamics of the system. References: Zañudo JGT and Albert R. An effective network reduction approach to find the dynamical repertoire of discrete dynamic networks. Chaos 23 (2), 025111 (2013); Steinway SN et al. Network Modeling of TGFß Signaling in Hepatocellular Carcinoma EpithelialtoMesenchymal Transition Reveals Joint Sonic Hedgehog and Wnt Pathway Activation. Cancer Research 74 (21), 5963–77 (2014); Zañudo JGTZ and Albert R. Cell fate reprogramming by control of intracellular network dynamics. arXiv:1408.5628 [qbio.MN]. In review (2014).
 January 20th, 2015 (02:30pm  03:30pm)
 Seminar: GAP Seminar
Title: Polyfolds and Fredholm theory
Speaker: Kris Wysocki, Penn State University
Location: MB106One of the main tools in symplectic topology is the study of moduli spaces of pseudoholomorphic maps defined on, perhaps punctured, Riemann surfaces with images in symplectic manifolds, symplectizations, or symplectic cobordisms. In general, these moduli spaces do not permit a satisfactory classical description in view of noncompactness phenomena. In the talk I will give a short introduction to the polyfold theory which provides an analytical framework to deal with these issues.
 January 20th, 2015 (02:30pm  03:45pm)
 Seminar: Logic Seminar
Title: Separation and reduction in secondorder arithmetic
Speaker: David Belanger, Cornell University
Location: MB315A family F of subsets of a set Z has the separation property if for every disjoint pair A,B in F, there is a partition of Z into two sets A_0,B_0 such that A is a subset of A_0, B is a subset of B_0, and A_0,B_0 are both in F. We look at the separation properties for several F, Z pairs, their roles in reverse mathematics, and a few directions these roles suggest for future research.
 January 20th, 2015 (03:30pm  06:00pm)
 Seminar: Working Seminar: Dynamics and its Working Tools
Title: Multifractal analysis for multiple mixing, II
Speaker: Joerg Schmeling, University of Lund
Location: MB114  January 21st, 2015 (12:05pm  01:20pm)
 Seminar: Geometry Luncheon Seminar
Title: Closed orbits of pseudoAnosov flows: cardinality and length growth
Speaker: Sergio Fenley, Florida State University
Location: MB114There are Anosov and pseudoAnosov flows so that some orbitsare freely homotopic to infinitely many other orbits. Given such an infinite free homotopy class we analyse its interaction with the torus decomposition of the manifold: whether they can all be contained in a Seifert piece or atoroidal piece. There is a natural ordering of an infinite subset of such a collection, indexed as (gamma_i). We analyse the growth of the length of gamma_i as a function of i.We obtain some inequalities which have some ergodic theory consequences. This is a joint work with Thomas Barthelme.
 January 21st, 2015 (03:30pm  05:30pm)
 Seminar: Applied Algebra and Network Theory Seminar
Title: (Cancelled due to weather )Tensor networks, model reduction, and error modeling
Speaker: Jacob Biamonte, ISI Foundation
Location: MB315  January 22nd, 2015 (11:15am  12:05pm)
 Seminar: Algebra and Number Theory Seminar
Title: No seminar today
Speaker: See Colloquium, Job Candidate
Location: MB106  January 22nd, 2015 (03:30pm  04:20pm)
 Seminar: Department of Mathematics Colloquium
Title: Interpolation problems in algebraic geometry
Speaker: Jack Huizenga (Host: Yuxi Zheng), University of Illinois at Chicago
Location: MB114Classical Lagrangian interpolation states that one can always prescribe n+1 values of a single variable polynomial of degree n. This result paves the way for many beautiful generalizations in algebraic geometry. I will discuss a few of these generalizations and their relevance to important questions in mathematics. I will then discuss recent connections between interpolation problems and the birational geometry of Hilbert schemes of points and moduli spaces of vector bundles.
 January 23rd, 2015 (03:30pm  05:00pm)
 Seminar: CCMA PDEs and Numerical Methods Seminar Series
Title: A simple finite element method simulating the incompressible high Reynolds number flow and boundary layer separation.
Speaker: Yunhua Xue, Nankai University
Location: MB315In this talk, we apply the simple finite element numerical scheme to simulate the vorticitystream function formulation of the incompressible flow over a triangular domain and analyze its boundary layer separation. Compared with many classical finite element fluid solvers, this method avoids a Stokes solver, and only two Poissonlike equations need to be solved at each time step/state. Numerical experiments over this irregular domain for high Reynolds number $Re=10^4, 10^5$ flows are investigated. At same time, the dynamical mechanism of the boundary layer separation, including the bifurcation location and critical time are qualitatively reported.
 January 26th, 2015 (12:20pm  01:30pm)
 Seminar: CCMA Luncheon Seminar
Title: Modeling Blood CellSubstrate Interaction and BiofilmFluid Interaction
Speaker: Zhiliang Xu, University of Notre Dame (Host: Chun)
Location: MB114This is an introductory talk for the CAM Colloquium.
 January 26th, 2015 (02:30pm  03:30pm)
 Seminar: Computational and Applied Mathematics Colloquium
Title: Modeling Blood CellSubstrate Interaction and BiofilmFluid Interaction
Speaker: Zhiliang Xu, University of Notre Dame (Host: Chun)
Location: MB106In this talk, two different models will be discussed. The first model is for studying blood cellenvironment interaction, specially plateletblood vessel wall interaction. Platelets aggregation at the injury site of the blood vessel occurring via plateletplatelet adhesion, tethering and rolling on the injured endothelium is a critical initial step in blood clot formation. To understand this critical step, a hybrid model is developed to represent membranes of biological cells and the distributedLagrangemultiplier/fictitiousdomain (DLM/FD) formulation is used for simulating the fluidcell interactions. For modeling cellsubstrate adhesion, a stochastic receptorligand binding submodel is used. In the second part of the talk, a biofilm model which systemically couples bacterial, extracellular polymeric substances (EPS) and solvent phases in biofilm will be discussed. The model is derived by using energetic variational approach and phasefield method coupling different phases together. An unconditionally energystable numerical splitting scheme is implemented for computing numerical solution of the model efficiently.
 January 26th, 2015 (03:35pm  04:35pm)
 Seminar: Dynamical systems seminar
Title: Leafwise entropy rigidity for foliations.
Speaker: Christopher Connell, Indiana University at Bloomington
Location: MB114We prove an entropy rigidity statement for general foliated maps f: M > N between compact foliated spaces in the sense of Besson, Courtois and Gallot. In particular, we establish an isoentropic inequality with respect to a transverse quasiinvariant measure which is optimal when almost every leaf of M is locally symmetric. We give some applications of this as well, and indicate how it relates to the entropy rigidity conjecture for higher rank spaces. This is joint work with Zhenyu Li.
 January 27th, 2015 (11:15am  12:05pm)
 Seminar: Combinatorics/Partitions Seminar
Title: Partitions associated with the Ramanujan/Watson mock theta functions omega(q) and nu(q)
Speaker: Ae Ja Yee, PSU
Location: MB106Recently, George Andrews, Atul Dixit, and I have discovered very interesting partition theorems that are related to the mock theta functions omega(q) and nu(q). For instance, the generating function for partitions where each part is less than twice the smallest part equals q times omega(q). In this talk, I will present those discoveries and some related arithmetic properties. This will be a preliminary report on the collaboration with Andrews and Dixit.
 January 27th, 2015 (01:00pm  02:00pm)
 Seminar: Theoretical Biology Seminar
Title: Mathematical modeling of malaria transmission
Speaker: Olivia Prosper, Department of Mathematics, Dartmouth College
Location: MB106Sir Ronald Ross’ discovery of the transmission mechanism of malaria in 1897 inspired a suite of mathematical models for the transmission of vectorborne disease, known as RossMacdonald models. I introduce a common formulation of the RossMacdonald model and discuss its extension to address a current topic in malaria control: the introduction of malaria vaccines. Following over two decades of research, vaccine trials for the malaria vaccine RTS,S have been completed, demonstrating an efficacy of roughly 50% in young children. Regions with high malaria prevalence tend to have high levels of naturally acquired immunity (NAI) to severe malaria, leading to large asymptomatic populations. I introduce a malaria model developed to address concerns about how these vaccines will perform in regions with existing NAI, discuss some analytic results and their public health implications, and reframe our question as an optimal control problem.
 January 27th, 2015 (02:30pm  03:30pm)
 Seminar: GAP Seminar
Title: Symmetry and Geometric Structure for the Worpitzky identity
Speaker: Nick Early, Penn State University
Location: MB106The classical Worpitzky identity for the symmetric group $S_n$ decomposes a cubical lattice into $n!$ simplices of different sizes, each with a multiplicity counted by the number of permutations of $n$ with a fixed number of descents. It is wellknown in combinatorics that the Eulerian numbers can be represented as volumes of suitably normalized hypersimplices. We show how the Worpitzky identity encodes localization data for a system of simplicial polyhedral cones which emerge from the $A_n$ simple root system, and becomes now an isomorphism between two new graded, simplicial symmetric group representations.
 January 27th, 2015 (02:30pm  03:30pm)
 Seminar: Center for Dynamics and Geometry Colloquium
Title: Fourier dimension and its modifications
Speaker: Joerg Schmeling, Lund University
Location: MB114Fourier dimension has proved to be a useful tool to estimate Hausdorff dimensions of subsets of $\mathbb{R}^n$. It is also used in metric number theory and harmonic analysis. However it is not really justified to call it a dimension. We will investigate stability of the Fourier dimension under unions of sets and give positive results as well as counterexamples. As an outcome of these studies we will propose a modification of the Fourier dimension. This modification regularizes this notion in several ways. First it behaves like a dimension. It also has an important counterpart for measures. In particular we can show that the set of Borel measures having a given Fourier dimension is determined by its joint zero sets.
 January 27th, 2015 (02:30pm  03:45pm)
 Seminar: Logic Seminar
Title: Hilbert's Tenth Problem for subrings of the rationals and number fields.
Speaker: Kirsten Eisenträger, Penn State
Location: MB315In 1970 Matiyasevich, building on work by Davis, Putnam and Robinson, proved that Hilbert's Tenth Problem is undecidable. Since then, analogues of this problem have been studied by considering polynomial equations over commutative rings other than the integers. The biggest open problem in the area is Hilbert's Tenth Problem over the rational numbers and over number fields in general. In this talk we will construct some subrings $R$ of the rationals that have the property that Hilbert's Tenth Problem for $R$ is Turing equivalent to Hilbert's Tenth Problem over the rationals. We will show that the same can be done for number fields. The rings will be constructed with a priority argument.
 January 27th, 2015 (03:30pm  06:00pm)
 Seminar: Working Seminar: Dynamics and its Working Tools
Title: Introduction to KAK theory.0. Local linearization of circle diffeomorphisms with Diophantine rotation number
Speaker: Federico Rodriguez Hertz, Penn State
Location: MB114  January 28th, 2015 (12:05pm  01:20pm)
 Seminar: Geometry Luncheon Seminar
Title: Variational principles for isometric embeddings and rigidity
Speaker: Ivan Izmestiev, FU Berlin (Visiting Penn State)
Location: MB114The discrete total scalar curvature of a manifold glued from euclidean (or hyperbolic) simplices is the sum of the lengths of edges multiplied with the angular defects around them (a volume term is added in the hyperbolic case). This functional has very nice variational properties with respect to the length variables: its critical points correspond to vanishing angle defects, that is to constant curvature metrics. In certain cases we are able to determine the signature of its second variation, which looks very much like that of its smooth counterpart. We will present some applications to isometric embeddings and rigidity.
 January 28th, 2015 (03:30pm  05:00pm)
 Seminar: Complex Fluids Seminar
Title: Stability of steady states of the NavierStokesPoisson equations with nonflat doping profile
Speaker: Yong Wang, Xiamen University
Location: MB106We consider the stability of the steady state of the compressible NavierStokesPoisson equations with the nonflat doping profile. We prove the global existence of classical solutions near the steady state for the large doping profile. For the small doping profile, we prove the time decay rates of the solution provided that the initial perturbation belongs to L^p with 1=< p< 3/2.
 January 29th, 2015 (11:15am  12:05pm)
 Seminar: Algebra and Number Theory Seminar
Title: Descent for specializations of Galois branched covers
Speaker: Ryan Eberhart, Penn State University
Location: MB106Let G be a finite group and K a number field. Hilbert's irreducibility theorem states that a regular GGalois branched cover of P^1_K, the projective line over K, gives rise to GGalois field extensions of K by specializing the cover (i.e. plugging in specific coordinates into the equations for the cover). A common tactic for progress on the Inverse Galois Problem over Q is to construct a GGalois branched cover of P^1_Q. We investigate a related line of inquiry: given a GGalois branched of P^1_K, do any of the specializations descend to a GGalois field extension of Q, even though the cover itself may not? We prove that the answer is yes when G is cyclic if one allows specializations at closed points. However, we show that the answer is in general no if we restrict to specializations at Krational points. This is joint work with Hilaf Hasson.
 January 29th, 2015 (02:30pm  03:30pm)
 Seminar: Noncommutative Geometry Seminar
Title: Oka principle: commutative and noncommutative. I
Speaker: Nigel Higson, Penn State
Location: MB106The original Oka principle asserts that smooth vector bundles on closed, complex submanifolds of complex affine space admit unique holomorphic structures. It has obvious implications for Ktheory, and, through them, potential applications to noncommutative geometry, especially to the BaumConnes conjecture. I'll discuss the original result (due to Oka and Grauert), and then actual as well as potential extensions to the noncommutative context.
 January 29th, 2015 (03:30pm  04:20pm)
 Seminar: Department of Mathematics Colloquium
Title: Faculty Meeting
Speaker: Faculty Meeting, Pennsylvania State University
Location: MB114  January 30th, 2015 (03:30pm  05:00pm)
 Seminar: CCMA PDEs and Numerical Methods Seminar Series
Title: Nonlinear approximation theory for the homogeneous Boltzmann equation
Speaker: Binh Tran, Basque Center for Applied Mathematics, Spain
Location: MB315
Abstract: http://www.math.univparis13.fr/~binh/A challenging problem in solving the Boltzmann equation numerically is that the velocity space is approximated by a finite region. Therefore, most methods are based on a truncation technique and the computational cost is then very high if the velocity domain is large. Moreover, sometimes, nonphysical conditions have to be imposed on the equation in order to keep the velocity domain bounded. In this talk, we introduce the first nonlinear approximation theory for the Boltzmann equation. Our nonlinear wavelet approximation is nontruncated and based on a nonlinear, adaptive spectral method associated with a new wavelet filtering technique and a new formulation of the equation. The approximation is proved to converge and perfectly preserve most of the properties of the homogeneous Boltzmann equation. It could also be considered as a general frame work for approximating kinetic integral equations.