Doctoral Student Seminar: ​Shenghua He and Rajagopal Venkatesarami

Mar 22, 2019
12:30 PM
1:30 PM
Lopata 101
Rajagopal Venkatesaramani

Title: A Semantic Cover Approach to Topic Modeling

Abstract: We introduce a novel topic modeling approach based on constructing a semantic set cover for clusters of similar documents.

Specifically, our approach first clusters documents using their Tf-Idf representation, and then covers each cluster with a set of topic words based on semantic similarity, defined in terms of a word embedding. Computing a topic cover amounts to solving a minimum set cover problem. Our evaluation compares our topic modeling approach to LDA on three metrics: 1) qualitative topic match, measured using evaluations by MTurk human subjects, 2) performance on classification tasks using each topic model as a sparse feature representation, and 3) topic coherence. We find that qualitative judgments significantly favor our approach, the method outperforms LDA on topic coherence, and is comparable to LDA on document classification tasks.

Shenghua He

Title: Automatic microscopic cell counting by use of unsupervised adversarial domain adaptation and supervised density regression

Abstract: Accurate cell counting in microscopic images is important for medical diagnoses and biological studies. However, manual cell counting is very time-consuming, tedious, and prone to subjective errors. We propose a new density regression-based method for automatic cell counting that reduces the need to manually annotate experimental images. A supervised learning-based density regression model (DRM) is trained with annotated synthetic images (the source domain) and their corresponding ground truth density maps. A domain adaptation model (DAM) is built to map experimental images (the target domain) to the feature space of the source domain. By use of the unsupervised learning-based DAM and supervised learning-based DRM, a cell density map of a given target image can be estimated, from which the number of cells can be counted. Results from experimental immunofluorescent microscopic images of human embryonic stem cells demonstrate the promising performance of the proposed counting method.