【主 题】 Automatic identification of curve shapes with applications to ultrasonic vocalization

【报告人】 唐炎林, 研究员

华东师范大学

【时 间】 2019年11月15日   16:00-17:00

【地 点】 上海财经大学统计与管理学院大楼1208会议室

【摘 要】Like human beings, many animals produce sounds for communication and social interactions. The vocalizations of mice have the characteristics of songs, consisting of syllables of different types determined by the frequency modulations and structure variations. To characterize the impact of social environments and genotypes on vocalizations, it is important to identify the patterns of syllables based on the shapes of frequency contours. Using existing hypothesis testing methods to determine the shape classes would require testing various null and alternative hypotheses for each curve, and is impractical for vocalization studies where the interest is on a large number of frequency contours. We propose a new penalization-based method, which provides function estimation and automatic shape identification simultaneously. The method estimates the functional curve through quadratic B-spline approximation, and captures the shape feature by penalizing the positive and negative parts of the first two derivatives of the spline function in a group manner. Under some regularity conditions, we show that the proposed method can identify the correct shape with probability approaching one, and the resulting nonparametric estimator can achieve the optimal convergence rate. Simulation shows that the proposed method gives more stable curve estimation and more accurate curve classification than the unconstrained B-spline estimator, and it is competitive to the shape-constrained estimator assuming prior knowledge of the curve shape.  The proposed method is applied to the motivating vocalization study to examine the effect of Methyl-CpG binding protein 2 gene on the vocalizations of mice during courtship.

【嘉宾简介】唐炎林，华东师范大学统计学院研究员。2012年1月于复旦大学统计系获得博士学位，师从朱仲义教授。2012年5月起在同济大学数学系工作，历任讲师、副教授，2019年1月加入华东师范大学统计学院。主要研究方向为分位数回归、高维数据统计推断、删失数据，主持国家自然科学基金面上项目、青年项目各一项，上海市浦江人才计划一项。

【主持人】尤进红