What to do when the size and complexity of your model essentially prevent you from using it? Well, get a smaller and simpler model... At the heart of this dimension reduction process is the notion of parameter importance which, ultimately, is part of the modeling process itself. Global Sensitivity Analysis (GSA) aims at efficiently identifying important…
In this talk we will discuss new classes of models that seek to describe evolution of a congregation of agents based on laws of self-organization. These models appear in a broad range of applications -- from biological sciences to social behavior. We focus on two long time phenomena: flocking and alignment. It has been a mathematical challenge…
This talk describes tips and tricks for building a successful career in the quantitative sciences. It covers research strategies, work/life balance, networking, and management of the portfolio of activities needed for different kinds of careers (academic, government, and industry). There is particular emphasis on how the professional societies can help advance your career. All graduate…
Mathematical modeling is a way for researchers to visualize components of a system and analyze how those components interact. When these models become significantly large, many problems arise. Here are a few: 1. As models increasingly complex with a myriad of parts, it is prudent for the researcher to ask whether all of these…
Target Audience: First and Second Years
Following Beilinson and Drinfeld, we describe vertex algebras as Lie algebras in a certain pseudo-tensor category. More precisely, starting from a vector superspace V with a linear operator on it, we introduce the operad of n-ary chiral operations on V. When V is equipped with a vertex algebra structure, this allows us to define the cohomology of V with…
Accurate estimation of microseismic events (small earthquakes) generated during hydraulic fracturing of low permeability rocks such as shale enables important characterization of hydraulic fracture networks. Determining the orientation of the fracture is important in characterizing the effectiveness of the stimulation process. We consider the source as separable in time and space and invert for a…
The finite minuscule and d-complete posets generalize Young and shifted Young diagrams. They have many nice combinatorial properties; for example, minuscule posets are Gaussian and Sperner, and d-complete posets have the hook length and jeu de taquin properties. Infinite analogs of the colored minuscule posets were used by R.M. Green to construct representations of many…
Poro-elastic and poro-visco-elastic models describe fluid flow through porous, deformable media. They are relevant in many applications in bioengineering and medicine, such as tissue perfusion and fluid flow inside cartilages and bones. In this talk, I will discuss the application of these models specifically to optical perfusion and its relation to glaucoma, as well as…
Geophysical seismic exploration, as well as radar and sonar imaging, require the solution of large scale forward and inverse problems for hyperbolic systems of equations. In this talk, I will show how model order reduction can be used to address some intrinsic difficulties of these problems. In model order reduction, one approximates the response (transfer…
Inspired by Bar-Natan's description of Khovanov homology, we discuss thin posets and their capacity to support homology and cohomology theories which categorify rank-statistic generating functions. Additionally, we present two main applications. The first, a categorification of certain generalized Vandermonde determinants gotten from the Bruhat order on the symmetric group by applying a special TQFT to…
In fibroblasts responding to gradients of platelet-derived growth factor (PDGF), an important chemoattractant in development and wound healing, signaling through the phospholipase C (PLC)/protein kinase C (PKC) pathway proved necessary for chemotaxis, whereas pathways that collaborate to activate the Arp2/3 complex were found to be dispensable. PKC is activated through its binding to the lipid…
This talk focuses on differential problems describing the flow of a viscous fluid in deformable domains. Such problems include flow in compliant tubes, often adopted for the modeling of arterial blood flow, and flow through deformable porous media, often adopted for the modeling of tissue perfusion. The mixed hyperbolic-parabolic-elliptic nature of these systems guides the…
Anticipating abrupt changes in ecosystem state is key for ecosystem management and preservation. Detailed knowledge of ecological mechanisms behind a critical transition is often difficult to attain, and the theory of resilience - assessment of the ability of a system to withstand disturbances - provides a pathway to circumvent this problem. Loss of system resilience…
Target Audience: Third, Fourth, and Fifth Years
Multiline queues were introduced by Ferrari and Matrin as a tool for understanding the steady state of the Totally Asymmetric Simple Exclusion Process (TASEP) on a ring. Since then, they have attracted independent interest as combinatorial objects. A queue can be described as a transformation of words by a combinatorial rule (related to the Lascoux-Schützenberger action of the symmetric group). A…
We address global sensitivity analysis for models with high-dimensional inputs and function-valued (functional) outputs. Variance-based global sensitivity approaches based on Sobol' indices have been proven useful in a wide range of outputs. However, Sobol' indices can be challenging to compute for computationally intensive models with a large number of parameters. We propose derivative based global…