Veranstaltungen

zum Archiv

Dienstag, 11.06.2019, 15:00 Uhr (WIAS-405-406)
Seminar Modern Methods in Applied Stochastics and Nonparametric Statistics
Dr. N. Tapia, WIAS Berlin:
Signatures in shape analysis
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, 4. Etage, Raum: 405/406

Weitere Informationen
Seminar Modern Methods in Applied Stochastics and Nonparametric Statistics

Veranstalter
WIAS Berlin
11. Juni 2019 (WIAS-ESH)
Workshop/Konferenz: Colloquium in Honor of the 80th Birthday of Klaus Schneider
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Veranstalter
WIAS Berlin
Mittwoch, 12.06.2019, 10:00 Uhr (WIAS-ESH)
Forschungsseminar Mathematische Statistik
Prof. S. Müller, University of Sydney, Australia:
c2pLasso: The categorical-continuous pliable Lasso to identify brain regions affecting motor impairment in Huntington disease
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Abstrakt
In many clinical studies, prediction models are essential for forecasting and monitoring the progression of a disease. Developing prediction models is a challenge when dealing with high-dimensional data since we do not know which variables are related to the response variable of interest and this relationship may depend on other continuous or categorical modifying variables as well. We formalize this problem as the varying-coefficient model selection and propose a novel variable selection method, c2pLasso, that accounts for both continuous and categorical modifying variables.
Our contributions are three-fold:
1. The c2pLasso method is shown to better screen irrelevant variables over the existing method that ignores the group structure of categorical modifying variables and to lead to a prediction model with higher accuracy and easier interpretation.
2. Our method adequately considers the pre-specified group structure among modifying variables in addition to unstructured modifying variables.
3. The c2pLasso is empirically shown to perform better than existing methods such as the Lasso and pLasso even when there is no categorical modifying variable or any pre-specified group structure among modifying variables. Using simulation studies, we show our method selects less irrelevant variables compared to existing methods while choosing relevant variables correctly. This provides us with a prediction model with higher specificity, lower false discovery rate and lower mean squared error. The proposed methodology is motivated by and illustrated using data from a Huntington disease study; the result identifies brain regions associated with motor impairment accounting for differentiated relationship by disease severity. To the best of our knowledge, our study is the first to identify the interaction effect between disease severity and the volume of brain regions in a varying-coefficient model framework.
This is joint work with Rakheon Kim and Tanya Garcia, both at Texas A&M, Department of Statistics.

Veranstalter
Humboldt-Universität zu Berlin
Universität Potsdam
WIAS Berlin
Mittwoch, 12.06.2019, 15:15 Uhr (WIAS-ESH)
Berliner Oberseminar „Nichtlineare partielle Differentialgleichungen” (Langenbach-Seminar)
F. Della Porta, Max-Planck-Institut für Mathematik Leipzig:
The nonlocal Cahn--Hilliard--Hele--Shaw system with regular and singular potential
mehr ... Veranstaltungsort
Weierstraß-Institut, Mohrenstr. 39, 10117 Berlin, Erdgeschoss, Erhard-Schmidt-Hörsaal

Abstrakt
The Cahn--Hilliard--Hele--Shaw system (also called the Cahn--Hilliard--Darcy system) can be used to describe the evolution of binary immiscible fluids in a Hele--Shaw cell or in porous media, and has been recently used as a buildingblock for some tumor-growth models. In my talk, I will introduce a physically motivated nonlocal variant of the Cahn--Hilliard--Hele--Shaw system, and present some related analytical results. These include the well-posedness of the system, the existence of a global attractor, and the convergence of solutions to equilibria as time goes to infinity (in the two-dimensional case). We discuss both the case with regular and singular potential.

Veranstalter
Humboldt-Universität zu Berlin
WIAS Berlin