Where: Kirwan Hall 1311

Speaker: () -

Where: Kirwan Hall 1311

Speaker: Joey Iverson (UMD) -

Where: Kirwan Hall 1311

Speaker: Anirudha Poria () -

Abstract: It is well known that the Gabor expansions converge to identity operator in weak* sense on the Wiener amalgam spaces as sampling density tends to infinity. In this talk, I will discuss the convergence of Gabor expansions to identity operator in the operator norm as well as weak* sense on Wiener amalgam spaces as the sampling density tends to infinity. Also discuss the validity of the Janssen's representation and the Wexler-Raz biorthogonality condition for Gabor frame operator on Wiener amalgam spaces.

Where: Kirwan Hall 1311

Speaker: TBA () -

Where: Kirwan Hall 1311

Speaker: Sivaram Narayan (Central Michigan University) -

Abstract: We say that a bounded operator T on a complex Hilbert space H is complex symmetric if there exists a conjugation (i.e., a conjugate linear, isometric involution) J such that T=JT^*J. In this talk, we will first discuss a few general results about complex symmetric operators on a Hilbert space. We will then focus for most of the talk on the complex symmetry of composition operators C_\varphi f = f \circ \varphi induced on the Hardy space H^2 by analytic self-maps \varphi of the open unit disk D. We show that there are complex symmetric composition operators on H^2 induced by \varphi that are linear-fractional but not automorphisms. In doing so, we answer a recent question of Noor, and partially answer the original problem posed by Garcia and Hammond.

Where: Kirwan Hall 1311

Speaker: Stephen Casey (American University) -

Abstract: Our talk addresses the problems of extracting information from periodic point processes. These problems arise in numerous situations, from radar pulse repetition interval analysis to bit synchronization in communication systems. We divide our analysis into two cases: periodic processes created by a single source, and those processes created by several sources. We wish to extract the fundamental period of the generators, and, in the second case, to

deinterleave the processes.

We first present very efficient algorithm for extracting the fundamental period from a set of sparse and noisy observations of a single source periodic process. The procedure is computationally straightforward, quickly convergent, and stable with respect to noise. Its use is justified by a theorem which shows that for a set of randomly chosen positive integers, the probability that they do not all share a common prime factor approaches one quickly as the cardinality of the set increases. The proof of this theorem rests on a probabilistic interpretation of the Riemann zeta function. We then build upon this procedure to deinterleave

and then analyze data from multiple periodic processes. This relies on the probabilistic interpretation of the Riemann zeta function, the equidistribution theorem of Weyl, and techniques from spectrum analysis. We present simulations of the procedures, which were developed jointly by the speaker and Kevin Duke of American University.

We close by using our a probabilistic interpretation of the Riemann zeta function to to develop numerical approximations of the sums $\sum_{n=1}^\infty \frac{1}{n^{2k+1}}$, for k in the natural numbers.

Where: Kirwan Hall 1311

Speaker: Nate Strawn (Georgetown University) -

Abstract: We demonstrate the connectivity of algebraic varieties of finite unit norm tight frames (FUNTFs). Our central technique involves explicit continuous lifts of paths from the polytope of eigensteps (or, Gelfand-Tsetlin patterns) to spaces of FUNTFs. After demonstrating this connectivity result, we refine our analysis to show that the set of nonsingular points on these spaces is also connected. Using tools from real algebraic geometry, this refined connectivity result shows that FUNTFs varieties are irreducible in the algebro-geometric sense. This last result allows us to show that generic FUNTFs are full spark, and hence the full spark FUNTFs are dense in the space of FUNTFs. This resolves an important theoretical question regarding the application of FUNTFs in the field of Compressed Sensing. We conclude with open questions and future directions. This is joint work with Dustin Mixon and Jameson Cahill.

Where: Kirwan Hall 1311

Speaker: Irina Mitrea (Temple University) -

Abstract: This talk serves as an illustration of the principle that combining techniques originating in Complex Variables, Geometric Measure Theory, and Harmonic Analysis creates a potent mix, leading to sharp versions of many significant results in Complex Analysis and opening the door for pursuing new directions all together. Specifically, I will concentrate on Scattering Theory for null-solutions of perturbed Dirac operators in exterior Ahlfors-David regular domains, treated via methods and tools of a Complex Variables flavor such as higher dimensional versions of the Cauchy's operator, Hardy spaces, Fatou theorems, unique continuation property, etc.

Where: Kirwan Hall 1311

Speaker: Greg Coxson (United States Naval Academy) -

Abstract: The problem of optimizing binary and quad-phase aperiodic autocorrelation sidelobe levels is notoriously difficult, and likely NP-hard. Some have likened these problems to that of seeking needles in a haystack. I have at times tried to find aspects of these problems that can be used to predict behavior for all code lengths N, but these efforts have always ended in frustration. However, recently, I posed a question about the binary case that not only yielded an enumeration result for all code lengths N, but even led to a similar result for the quad-phase case. A side benefit of the work is a pair of simple algorithms for visiting, one-by-one, single representatives of each PSL equivalence class for any code length N of interest. Such algorithms can be employed, ideally in combination with other methods, to expedite searches for low-sidelobe binary and quad-phase codes.

Where: Kirwan Hall 1311

Speaker: Alex Cloninger (Yale) -

Where: Kirwan Hall 1311

Speaker: James Murphy (Johns Hopkins University) -

Where: Kirwan Hall 1311

Speaker: Christiana Sabett (UMD) -

Where: Kirwan Hall 3206

Speaker: () -

Where: Kirwan Hall 3206

Speaker: Rafael Reisenhofer (University of Bremen) -

Where: Kirwan Hall 3206

Speaker: FFT 2017 (FFT 2017) - http://www.norbertwiener.umd.edu/FFT/2017/schedule.html

Abstract: See the list of speakers and abstracts at http://www.norbertwiener.umd.edu/FFT/2017/schedule.html.

Main lectures:

1) Charles Chui (Stanford) Thursday, February 16, 2017, 4:15-5:00

2) Robert Kanigel (MIT) Thursday, February 16, 2017, 6:40-7:30

3) David Donoho (Stanford) Friday, February 17, 2017, 3:30-4:30

Where: Kirwan Hall 3206

Speaker: FFT 2017 () - http://www.norbertwiener.umd.edu/FFT/2017/schedule.html

Abstract: Abstract: See the list of speakers and abstracts at http://www.norbertwiener.umd.edu/FFT/2017/schedule.html.

David Donoho (Stanford) Friday, February 17, 2017, 3:30-4:30

Where: Kirwan Hall 3206

Speaker: Yen Do (UVA) -

Where: Kirwan Hall 3206

Speaker: Michelle Quirk () -

Where: Kirwan Hall 3206

Speaker: Andrew Childs (UMD) -

Where: Kirwan Hall 3206

Speaker: Alfredo Nava-Tudela (UMD) -

Where: Kirwan Hall 3206

Speaker: Michael Robinson (American University) -

Where: Kirwan Hall 3206

Speaker: Addison Bohannon (UMD) -

Where: Kirwan Hall 3206

Speaker: Sui Tang (JHU) -