Lefschetz Center for Dynamical Systems Seminar
Brown University Center for Statistical Sciences Seminar
Department of Epidemiology and Public Health, Yale University School of Medicine | |
* Refreshments following seminar at 167 Angell Street, 2nd floor conference room |
Abstract: Coupled with environmental factors, genes contribute to numerous human diseases and traits. While there are many epidemiological methods to assess the familial clustering of traits, few are flexible enough to accommodate interactions between covariates and familial factors. In this paper, we propose and develop a frailty model that establishes an integrated framework to evaluate familial transmission of a disease by controlling for covariate effects and conveniently testing the interactions between covariates and familial factors. We also present a peeling algorithm that dramatically reduces the computational burden. This frailty model is employed to examine the familial transmission of major subtypes of alcoholism, namely, alcohol abuse and dependence. We conclude that alcohol dependence is strongly familial whereas alcohol abuse expresses a marginally significant pattern of familial transmisssion. Moreover, females manifest alcoholism at a lower threshold, and there is no sex-specific familial transmission of alcoholism after adjustment for the threshold effect.
This is a joint work with Kathleen Merikangas.
Stochastic Systems Seminar
Part of the Wayland Interdisciplinary Lecture Series on the
Simulation and Visualization of Physical Phenomena
Brown Applied Mathematics Pattern Theory and Vision Seminar
Abstract: In computer vision, objects are often represented by the boundary of their projection onto a plane (picture). So the problem of object recognition is often reduced to curve recognition up to Lie group action. In mathematical terms, the question we are trying to answer can be formulated as follows:
Given a Lie Group $G$ acting on a manifold $M$ and two curves $C_1, C_2 \in M$, does there exist a transformation $g\in G$ such that $G\cdot C_1=C_2$.
Our solution is based on Fels-Olver moving frames. We prolong the action of $G$ onto $M^{\times (n)}:=M\times M\times \ldots \times M$ ($n$ times), the {\em Cartesian space } of $M$, which is, in a sense. a discrete version of the jet bundle. Suitably chosen invariants of this action are used to parameterize a noise-resistant signature of optimal dimension. Our method is completely algorithmic and works for most Lie groups. The examples of the Euclidean, affine and similarity (Euclidean+ scaling) Lie groups will be discussed.
Brown University Analysis Seminar
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