- Department of Mathematics Colloquium Speaker Committee

- Because there might be a time delay in updating the webpage, please always check with the committee for the available dates.

** Refreshments** take place 30 minutes prior to the talk.

Typical Colloquium Talks are
Thursday, 4:00–4:50pm, in Pearce 227. Refreshments are in Pearce 216.

There might be some talks scheduled on a different day and time. The following table gives the most accurate information for each event.

Date |
Speaker |
Title (Scroll down for Abstract) |
Remark |

9/7/2017 | Department Meeting | Department Meeting | |

9/21/2017 | Amit Savkar (University of Connecticut) | From placement to classification a reliable assessment, feedback and instruction for freshmen level mathematics | |

9/28/2017 | Department Meeting | Department Meeting | |

10/5/2017 | Mary Martinez (OCRIE, CMU) | Civil Rights and Institutional Equity | 3:30 - 4:30 |

10/12/2017 | Gopal Prasad (University of Michigan) | Number Theory in Geometry | |

10/19/2017 | Vytaras Brazauskas (University of Wisconsin-Milwaukee) | Robust Claim Severity Models: Theory, Simulations, Examples | |

10/26/2017 | Department Meeting (Cancelled) | Department Meeting (Cancelled) | |

10/27/2017 Friday |
Mythily Ramaswamy (TIFR, Bangalore, India) | Control of PDE Models | 3:00 - 4:00 PE 223 |

11/2/2017 | |||

11/9/2017 | Katrina Piatek-Jimenez (CMU) | College Students' Perceptions of Mathematicians | |

11/16/2017 | |||

11/30/2017 | Department Meeting | Department Meeting | |

12/7/2017 |

**Speaker: ** Amit Savkar (September 21)

**Title: ** From placement to classification a reliable assessment, feedback and instruction for freshmen level mathematics

**Abstract: **
The talk will focus on two parts: i) the design and implementation of effective placement exam and intervention strategy for incoming freshmen. In particular it will focus on the reduction of DFW rates in calculus I and calculus II courses at the university of Connecticut. ii) classification of students using different modeling techniques such as latent class analysis, clustering techniques etc. The author will present results from simulation study of a million students on the effect of classification using mixture model for partial credit response and dichotomous response.

**Speaker: ** Mary Martinez (September 28)

**Title: ** Civil Rights and Institutional Equity

**Abstract: **
Discrimination, harassment, and violence can affect all of us. This training will help provide you with the tools to help promote a workplace free of harassment, discrimination, and sexual misconduct, as well as discuss your responsibilities under Title IX. The trainings will help all employees recognize harassment and sexual misconduct, and provide practical tips on creating a safe, inclusive environment.

**Speaker: ** Gopal Prasad (October 12)

**Title: ** Number Theory in Geometry

**Abstract: **
Historically, geometry has played a very important role in the development of other branches of mathematics including Number Theory. In fact, the first irrational algebraic numbers arose in geometry, through Pythagoras theorem! In my talk, I will show how Number Theory has been used recently in Algebraic Geometry and Riemannian Geometry to settle some interesting problems. In my work with Sai-Kee Yeung (Purdue U.) on classification of fake projective planes and their higher dimensional analogues, and in my work with Andrei Rapinchuk (U. of Virginia) on isospectral locally symmetric spaces, results and estimates from Number Theory were crucial.

I recall that a fake projective plane (fpp) is a smooth complex projective algebraic surface with same Betti numbers as the complex projective plane, but which is not isomorphic to the complex projective plane. The firs example of such surfaces was constructed by David Mumford. It was an important problem in the theory of algebraic surfaces to determine them all. My work with Sai-Kee Yeung classified fpp's in 28 classes and we now know that altogether there are 100 fake projective planes. We have also determined their higher dimensional analogues.

There is a famous question formulated by Mark Kac: "Can we hear the shape of a drum?" In precise mathematical terms the question is: "Does the spectrum (= set of eigenvalues together with their multiplicities) of the Laplace-Beltrami operator on a compact Riemannian manifold determine the manifold up to isometry". The answer is "no" in general. However, for specific class of manifolds, one can expect a "better'' answer. Jointly with Rapinchuk, I have investigated this question for locally symmetric spaces and the answer turned out to be quite surprising.

**Speaker: ** Vytaras Brazauskas (October 19)

**Title: ** Robust Claim Severity Models: Theory, Simulations, Examples

**Abstract: **
Many quantities arising in non-life insurance depend on
claim severity distributions, which are usually modeled
assuming a parametric form. Obtaining good estimates of
the quantities, therefore, reduces to having good estimates
of the model parameters. However, the notion of 'good estimate'
depends on the problem at hand. For example, the maximum
likelihood estimators (MLE) are efficient, but they generally
lack robustness. Since outliers are common in insurance loss
data, it is therefore important to have a method that allows
one to balance between efficiency and robustness.

In this talk, we suggest a general estimation method that
we call the method of trimmed moments (MTM). This method is
appropriate for various model-fitting situations including
those for which a close fit in one or both tails of the
distribution is not required. The MTM estimators can achieve
various degrees of robustness, and they also allow the decision
maker to easily see the actions of the estimators on the data,
which makes them particularly appealing. We illustrate these
features with detailed theoretical analyses and simulation
studies of the MTM estimators in the case of location-scale
families and several loss distributions such as lognormal and
Pareto. As a further illustration, we present two real-data
examples that involve ratemaking and risk measuring exercises.
The first data set concerns hurricane damages in the United
States from 1925 to 1995, and the second represents total
damages done by 827 fires in Norway for the year 1988.

This is a joint work with B. Jones and R. Zitikis (University
of Western Ontario). Support by a grant from the Actuarial
Foundation, the Society of Actuaries, and the Casualty Actuarial
Society is gratefully acknowledged.

**Speaker: ** Mythily Ramaswamy (October 27)

**Title: ** Control of PDE Models

**Abstract: **
Starting with a brief introduction to
control of ODE systems, I will discuss similar
issues for PDE systems. The focus will be on
linear viscoelastic fluid flow
models, a system of
coupled partial differential equations for velocity
and stress.

**Speaker: ** Katrina Piatek-Jimenez (November 9)

**Title: ** College Students' Perceptions of Mathematicians

**Abstract: **
Society's perceptions of mathematicians can affect how individuals view those who enjoy mathematics and those who enter mathematical careers. These perceptions can also influence certain students' mathematics performance, perseverance, and career choice in the field. It is likely that negative perceptions more greatly affect women and certain minorities, who are already underrepresented in the field of mathematics. During this talk, I will discuss some of my work in this area of study. In particular, I will focus on my most recent study in which we asked 179 college students to "Draw a Mathematician" and to list five characteristics and five careers for mathematicians. We then conducted four focus group interviews with a total of 12 participants to explore their beliefs more deeply. During the focus group interviews, we asked the participants to view 16 photos of individual people and asked them to determine whether they believed each person was a mathematician or not and to explain their reasoning. Through our analysis of the data, we have found that many college students do have specific beliefs about mathematicians, however, some of their perceptions are different than those found in previous studies with younger children.