Colloquia - Fall 2025

If you are interested in giving a talk, please email Dr. Daniel Vallieres ( dvallieres@csuchico.edu).

Colloquia are typically held on Friday in Holt 175. Please see below for specific information. Refreshments are served at 3:45 pm and the talk begins at 4:00 pm. Everyone is invited to attend!

Upcoming talks 

Friday, Nov. 21st — Holt 175, 4:00 pm

Marcus A. Battraw —CSU Chico

Title: Understanding affected muscle activity in children with unilateral congenital below-elbow deficiency for intuitive control of dexterous prostheses

Abstract: Many complex factors affect whether children born with an upper limb deficiency (ULD) will use a prosthetic limb for daily activities. Children face higher rates of prosthesis abandonment at 35- 45%, compared to adults at 23-26% pointing to distinct and unresolved obstacles. Ultimately, for children to use their prosthesis, it must facilitate the effective performance of daily tasks and promote healthy social interactions. Although beginning to emerge, multiarticulate upper limb prostheses offer significant functional advantages for children, but remain sparse despite the continued advancement of mechatronic technologies that have benefited adults. Moreover, this population of children presents unique challenges, as they were born never having actuated a hand– a stark departure from those with acquired limb absence. Our work therefore builds the fundamental groundwork necessary for the effective translation of dexterous prosthetic hands to children with ULD. We begin with an examination of how typically developing children use their hands in daily activities to inform dexterous device development. Subsequently, a child-sized dexterous prosthetic hand was developed and benchmarked to serve as a dedicated research platform. Prior to utilizing this device, a cohort of children born with ULD were recruited, and an in-depth analysis of state-of-the-art prosthetic control, namely surface electromyography (sEMG) as a measure of affected muscle electrical activity, was conducted. Measures of movement consistency and distinguishability were investigated, and machine learning algorithms were tuned to decode missing-hand motor intent. Finally, we assessed the real-time performance these children have in executing missing hand movements to control a prosthetic limb. This work offers a crucial foundation for understanding muscle actuation and the use of advanced prostheses among children with ULD."

Past talks

Friday, Nov. 7th — Holt 175, 4:00 pm

Edward Roualdes —CSU Chico

Title: A new Metropolis-Hastings algorithm with an adaptive stepsize

Abstract: Designing algorithms to generate a sequence of random numbers from arbitrarily complex distributions is a challenging, but popular pastime for statisticians. The most common theory used to generate such numbers is called Markov Chain Monte Carlo (MCMC). Almost all tools in the world of MCMC use the Metropolis-Hastings algorithm. Many of these algorithms require, unfortunately, a fixed stepsize. In this talk, we introduce a new Metropolis-Hastings algorithm which allows the stepsize to adapt to part of the target distribution at each iteration. The material presented here is a joint effort with Barbara Grigg and Chase Wilson.

Friday, Oct 31 — Holt 175, 4:00 pm

Jie Peng — UC Davis

Title: Learning Directed Acyclic Graphical Models with Mixed Variables

Abstract: In this talk, we address the problem of learning directed acyclic graphical (DAG) models that include both continuous and binary variables. By employing appropriate models for each variable type, our approach allows either continuous or binary nodes to act as parents or children within the inferred graph.

To enhance robustness and reduce false positives, we incorporate a bootstrap aggregation strategy that also enables the effective use of prior information.

This framework is broadly applicable to the inference of gene regulatory networks from high-throughput omics data at both the bulk and single-cell levels.

In this talk, we will discuss its application to learning ligand–receptor interaction networks between adjacent tumor and immune/stromal cells using spatially resolved transcriptomic data.

Friday, Oct 17 — Holt 175, 4:00pm

Edgar Bering IV — San Jose State

Title: What is an Abstract Commensurator?

Abstract: Groups are the symmetries of things, but a group is also a highly symmetric object itself. The automorphism group of a group consists of all isomorphisms f : G → G and there is a rich theory of automorphism groups. Groups are richer still; containing many hidden symmetries, isomorphisms between finite-index subgroups. These hidden symmetries also form a group: the abstract commensurator of the group. The goal of this talk is to introduce the abstract commensurator from both algebraic and geometric points of view, illustrated with the central examples of the integers and the fundamental group of a torus.

Friday, Oct 3 — Holt 175 or via Zoom, 4:00 pm

Lew Ludwig — Denison Univ.

Title: From Disruption to Direction: Practical Steps for Faculty Engaging with AI

Abstract: Generative AI arrived uninvited, disrupting classrooms and scholarship alike. In this session, we’ll take stock of the current landscape by briefly surveying the “big three” models—ChatGPT, Claude, and Gemini—and what they mean for teaching. From there, I’ll demonstrate a simple three-step framework—Improve, Create, Integrate—that gives faculty a straightforward way to begin working productively with AI, whether they are brand new or already experimenting. Attendees will receive an electronic handout to explore later. If time permits, we’ll also look at ways AI can create new opportunities for engaging undergraduates in research. This talk is aimed at those new to, or in the early stages of, using AI.

Friday, Sept 26 — Holt 175, 4:00pm

Matt Krauel — CSU Sacramento

Title: There are Wronskian questions: A talk about some in the context of number theory and physics

Abstract: The Wronskian is a particular determinant built from input functions and their derivatives. It is typically introduced relatively early in a mathematician's journey, such as in a first course on ordinary differential equations. By inserting important number-theoretic functions called modular forms, the Wronskian has been used to help prove famous identities in number theory and provide machinery used in classifying conformal field theories in physics. We begin this talk by briefly reviewing these interesting involvements of the Wronskian. We then discuss recent research and new directions in this area by the speaker.

Past Colloquia