Events
Department of Mathematics and Statistics
Texas Tech University
Zebra and quagga mussel are among the world's notorious invasive species because of their large and widespread ecological and economic effects. Although these two species have similar life histories and share many ecological traits, they have some significant ecological differences and impacts. Understanding their long-term population dynamics is critical to determining impacts and effective management. To investigate how the population reproduction rates, intraspecific and interspecific competitions, as well as dispersal abilities affect the population persistence and spatial distributions of the two species in a spatially heterogeneous environment, we developed a dynamic model that describes the competitive interactions between zebra and quagga mussels in multiple patches. The dynamic analysis of the model yields some sufficient conditions that lead to population persistence, extirpation, as well as competitive exclusion and coexistence. By the numerical solutions of a two-patch model, we examine how the interplay between the local population dynamics in each patch and the individual dispersal between patches affects the competition outcomes of the two species in a spatially variable system.
This Biomath seminar may be attended Monday the 14th at 4:00 PM CST (UT-6) via this Zoom link. Meeting ID: 839 9465 7333 Passcode: BfriM6
Vertex algebras and factorization algebras are two approaches to chiral conformal field theory. Costello and Gwilliam describe how every holomorphic factorization algebra on the plane of complex numbers satisfying certain assumptions gives rise to a Z-graded vertex algebra. They construct some models of chiral conformal theory as factorization algebras. We attach a factorization algebra to every Z-graded vertex algebra.  | Wednesday
Feb. 16
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| Algebra and Number Theory
No Seminar
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In this talk we will present some connections between different random graph models. The classical Erdos-Renyi and Chung-Lu models with independent edges are well-known and easy to work with, whereas more complicated models such as regular random graph, scale-free random graph and preferential attachment random graph are more difficult to be studied. However there are similar properties which can be found on many different models. The connections between models allow us to prove a result on one model using a similar result on another model. We will also talk about some examples of properties which can be proved using this method such as convergence of limiting ditribution of eigenvalues, power law of eigenvalues, average distance, etc.
Keywords: Random graph; Preferential attachment; Erdos-Renyi; Chung-Lu; regular random graph.
Watch online via this Zoom link.
Nonlocal vector calculus, which is based on the nonlocal forms of gradient, divergence, and Laplace operators in multiple dimensions, has shown promising applications in fields such as hydrology, mechanics, and image processing. In this work, we study the analytical underpinnings of these operators. We rigorously treat compositions of nonlocal operators, prove nonlocal vector calculus identities, and connect weighted and unweighted variational frameworks. We combine these results to obtain a weighted fractional Helmholtz decomposition which is valid for sufficiently smooth vector fields. Our approach identifies the function spaces in which the stated identities and decompositions hold, providing a rigorous foundation to the nonlocal vector calculus identities that can serve as tools for nonlocal modeling in higher dimensions.
Please virtually attend the Applied Math seminar via this Zoom link Wednesday the 16th at 4 PM -- meeting ID: 937 2431 1192
This presentation reviews the significant progress in academic research on economic impact of climate change
and explores the implications for expected returns and strategic portfolio allocations across major public asset classes.
There have been numerous efforts to measure the environmental impact within a broader ESG framework with
a focus on microeconomic and firm-level implications. In this presentation, we assess the impact of climate change
on long-term expected returns across asset classes from a top-down macroeconomic perspective.
We use well-accepted climate risk scenarios to assess the potential impact of alternative climate scenarios on economic growth,
inflation, and asset returns for major asset classes.
Finally, we design hypothetical portfolios given these top-down assumptions and explore portfolio allocation implications.
Bio:
Yesim Tokat-Acikel, PhD, is a Managing Director, Head of Multi-Asset Research and Portfolio Manager for PGIM
Quantitative Solutions working within the Global Multi-Asset Solutions team.
In this capacity, she is responsible for the research, development, and portfolio management of systematic total
and absolute return investment solutions. She is also an investment lead for our global solutions efforts.
Prior to PGIM Quantitative Solutions, Yesim worked as a Senior Quantitative Analyst developing GTAA strategies at AllianceBernstein,
and as a Senior Investment Analyst for the Vanguard Group, where she built tactical and strategic asset
allocation models for retirement and private client markets.
Yesim’s articles have appeared in the Journal of Portfolio Management, the Journal of Investment Management,
Journal of Investing, Journal of Risk and Financial Management, the Journal of Economic Dynamics and Control,
the Strategic Management Journal, and the Journal of Financial Planning, among other leading publications.
She earned a BS in industrial engineering from Bilkent University in Turkey, an MS in industrial engineering
from the University of Arizona, Tucson, and a PhD in economics from the University of California, Santa Barbara.