报告题目：Boundary operator associated to $\sigma_k$ curvature

报 告 人：Yi Wang, Professor

时 间：2019年6月28日（周五）下午3:00-4:00

地 点：六号楼二楼报告厅

简 介：On a Riemannian manifold $(M, g)$, the $\sigma_k$ curvature is the $k$-th elementary symmetric function of the eigenvalues of the Schouten tensor $A_g$. It is known that the prescibing $\sigma_k$ curvature equation on a closed manifold without boundary is variational if k=1, 2 or $g$ is locally conformally flat; indeed, this problem can be studied by means of the energy $\int \sigma_k(A_g) dv_g$. We construct a natural boundary functional which, when added to this energy, yields as its critical points solutions of prescribing $\sigma_k$ curvature equations with general non-vanishing boundary data. Moreover, we prove that the new energy satisfies the Dirichlet principle. If time permits, I will also discuss applications of our methods. This is joint work with Jeffrey Case.

报告题目：On a Simple Estimation of the Proportional Odds Model …

报 告 人：Peng LIU

时 间：2019年7月2日（周二）上午10:00-11:00

地 点：六号楼二楼报告厅

简 介：Retrospective sampling can be useful in epidemiological research for its convenience to explore an etiological association. One particular retrospective sampling is that disease outcomes of the time-to-event type are collected subject to right truncation, along with other covariates of interest. For regression analysis of the right-truncated time-to-event data, the so-called proportional reverse-time hazards model has been proposed, but the interpretation of its regression parameters tends to be cumbersome, which has greatly hampered its application in practice. In this paper, we instead consider the proportional odds model, an appealing alternative to the popular proportional hazards model. Under the proportional odds model, there is an embedded relationship between the reverse-time hazard function and the usual hazard function. Building on this relationship, we provide a simple procedure to estimate the regression parameters in the proportional odds model for the right truncated d...

报告题目：Stability analysis on vortex sheets for 3-D compressib…

报 告 人：禹芳

时 间：2019年6月17日（周一）上午10:30-11:30

地 点：六号楼二楼报告厅

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