Current Talks

Refreshments are served 30 minutes before each talk in the Conference Room MSPB 335

Date Speaker Talk
September 21, 2017 at 3:30 p.m. in MSPB 370 Selvi Beyarslan, University of South Alabama

Algebraic Properties of Toric Rings of Graphs

Abstract: Let G = (V,E) be a simple graph. We investigate the Cohen-Macaulayness and algebraic invariants, such as the Castelnuovo-Mumford regularity and the projective dimension, of the toric ring k[G] via those toric rings associated to induced subgraphs of G.

October 18, 2017 at 6:00 p.m. in the University Library Auditorium
This talk is aimed at a general audience!
H. N. Nagaraja, College of Public Health, The Ohio State University

Fourth Satya Mishra Memorial Lecture

Statistical Methods for Public Health and Medicine

Abstract: Probabilistic modeling, statistical design, and inferential methods form the backbone of the remarkable advances in medicine and public health. General goals of inference are hypothesis testing (as in clinical trials), estimation (of risk for a disease), and prediction (of a future condition). We illustrate them by introducing examples, data types, statistical models, and methods. With summary statistics on commonly used statistical concepts in major public health and medical journals, we discuss popular statistical methods that drive current research in public health and medical science. We examine trends in biostatistical research and observe the evolving field of data science and bioinformatics.

October 19, 2017 at 3:30 p.m. in MSPB 370 H. N. Nagaraja, College of Public Health, The Ohio State University

Some Applications of Ordered Data Models

Abstract: We introduce three probability models for ordered data viewing them as (i) order statistics, (ii) record values, and (iii) order statistics and their concomitants. Applications of spacings of order statistics to auction theory and actuarial science will be illustrated with two examples: (a) properties of expected rent in regular and reverse auctions and (b) finding approximation to finite-time ruin probabilities for a company with large initial reserves. The problem of estimating mobility rates in search models using record value theory will be discussed. We will see how the concept of concomitants of order statistics can be used to model data-snooping biases in search engines, two-stage designs, and tests of financial asset pricing models. Some recent work on order statistics and spacings will be introduced.

November 2, 2017 at 3:30 p.m. in MSPB 370 Jonas Hartwig, Iowa State University


Abstract: TBA

November 9, 2017 at 3:30 p.m. in MSPB 370 William Hardesty, Louisana State University


Abstract: TBA

Previous Talks


Date Speaker Talk
September 19, 2017 Kodai Wada, Waseda University, Tokyo, Japan

Linking Invariants of Virtual Links

Abstract: In the first half of the talk, we introduce the notion of an even virtual link and define a certain linking invariant of even virtual links, which is similar to the linking number. Here, a virtual link diagram is even if the virtual crossings divide each component into an even number of arcs. The set of even virtual link diagrams is closed under classical and virtual Reidemeister moves, and it contains the set of classical link diagrams. For two even virtual link diagrams, the difference between the linking invariants of them gives a lower bound of the minimal number of forbidden moves needed to deform one into the other. Moreover, we give an example which shows that the lower bound is best possible.

In the second half of the talk, we define a polynomial invariant of any virtual link which is a generalization of the linking invariant above. The polynomial invariant is a natural extension of the index type invariants of virtual knots, for example, the writhe polynomial and the affine index polynomial.

September 7 & 14, 2017 Bin Wang, University of South Alabama

A Mixture Model for Next-Generation Sequencing Gene Expression Data I & II

Abstract: Gene expression data are usually highly skewed with a lot of weakly- or non-expressed genes. As a result, gene expression data profiled using next-generation sequencing (NGS) techniques usually contain a large amount of zero measurements. We propose to model the NGS data using a mixture model. Via data binning, the expectation-maximization algorithm performs well to estimate the distributions of gene profiles. We also propose a novel normalization method by assuming the existence of a common distribution among all gene profiles.

August 24, 2017 Andrei Pavelescu, University of South Alabama

Complete Minors of Self-Complementary Graphs

Abstract: Some topological properties of graphs are connected to the existence of complete minors. For a simple non-oriented graph G, a minor of G is any graph that can be obtained from G by a sequence of edge deletions and contractions. In this talk, we show that any self-complementary graph with n vertices contains a K[(n+1)/2] minor. We also prove that this bound is the best possible and present some consequences about which self-complementary graphs are planar, intrinsically linked or intrinsically knotted. This is joint work with Dr. Elena Pavelescu.

For colloquium talks from previous years click here