Title: Klingen Eisenstein series and symmetric square $L$-functions

Abstract: It is well-known in number theory that some of the deepest results come in connecting complex analysis in the form of $L$-functions with algebra/geometry in the form of Galois representations/motives. In this talk we will consider this for a particular case. Let $f$ be a newform of weight $k$ and full level. Associated to $f$ one has the adjoint Galois representation and the symmetric square $L$-function. The Bloch-Kato conjecture predicts a precise relationship between special values of the symmetric square $L$-function of $f$ with size of the Selmer groups of twists of the adjoint Galois representation. We will outline a result providing evidence for this conjecture by lifting $f$ to a Klingen Eisenstein series and producing a congruence between the Klingen Eisenstein series and a Siegel cusp form with irreducible Galois representation. time permitting, we will discuss a modularity result for a 4-dimensional Galois representation that arises from the congruence and studying a particular universal deformation ring. This is joint work with Kris Klosin.

Title: Hydrodynamics of Ciliary Swimming

Abstract:

Planktonic microorganisms are ubiquitous in water, and their population dynamics are essential for forecasting the behavior of global aquatic ecosystems. Their population dynamics are strongly affected by these organisms’ motility, which is generated by their hair-like organelles, called cilia or flagella. However, because of the complexity of ciliary dynamics, the precise role of ciliary flow in microbial life remains unclear.

In terms of fluid dynamics, ciliary swimming has been analyzed by using a squirmer model. A classical squirmer model propels itself by generating surface tangential and radial velocities. Recently, we developed a novel squirmer model in which, instead of a velocity being imposed on the cell surface, a shear stress is applied to the fluid on a stress shell placed slightly above the cell body. The shear stress expresses the thrust force generated by cilia, and the fluid must satisfy the no-slip condition on the cell body surface. The stress squirmer model has been successful in reproducing experimentally observed cell-cell interactions and cell-wall interactions.

In order to understand swimming energetics, we further developed a ciliate model incorporating the distinct ciliary apparatus. The hairy squirmer model revealed that over 90% of energy is dissipated inside the ciliary envelope. By using the hairy squirmer model, we found that there exists an optimal number density of cilia, which provides the maximum propulsion efficiency for all ciliates. The propulsion efficiency in this case decreases inversely proportionally to body length. Our estimated optimal density of cilia corresponds to those of actual microorganisms, including species of ciliates and microalgae, which suggests that now-existing motile ciliates and microalgae may have survived by acquiring the optimal propulsion efficiency.

Math club will meet this Thursday (March 9) at 5PM in Keller 303. There will be free pizza and soda. If you wish to attend, please RSVP at the discord group (contact Prof. Lodha for the link)..

The speaker is Dr. Samantha Schumacher who is a Mathematician at Target.

Title: Machine Learning & Artificial Intelligence for Product Availability at Target

Abstract: In this casual talk, we’ll talk about my semi-bizarre mathematical background and the non-linear path that got me into Supply Chain at Target. I will share how a direct application of ML and AI on my team is leading to extraordinary outcomes for Target’s Product Availability. I also want to offer some resume & application advice for those interested in a mathematical career in industry, particularly in retail. Because the direct path looks great on paper, but sometimes the meandering path can provide critical skills for future success.