arXiv subjects

Susmita Datta

Publications and source records attributed to Susmita Datta.

3 recordsLinked to original sources

arXiv2026

Sparse Reduced-rank Regression Methods for Spatially Misaligned Data with Application to Spatial Transcriptomics

Understanding the spatiotemporal dynamics of disease progression in relation to transcriptomic profiles provides key insights into complex conditions such as Alzheimer's disease. To enable such investigations, STARmap PLUS technology offers joint profiling of high-resolution spatial transcriptomics and protein detection within the same tissue section. Detailed visual and clustering-based analyses of STARmap PLUS data by Zeng et al. (2023) provided important insights into molecular and cellular changes associated with Alzheimer's disease pathology. Motivated by this work, we develop a kernel-weighted sparse reduced-rank regression framework that estimates associations between plaque size and neighboring cell-level transcriptomic profiles while enabling gene selection and borrowing strength across genes, cell types, and disease stages. The proposed approach is implemented in a fully automated manner with data-driven specification of key model components. Through simulation studies, we demonstrate the robustness of the proposed method and its superiority across a range of simulation scenarios. Applied to Alzheimer's disease data, the proposed framework uncovers biologically meaningful associations, highlighting its potential for advancing the understanding of disease mechanisms.

stat.AP↗

arXiv2019

MarZIC: A Marginal mediation model for Zero-Inflated Compositional mediators with applications to microbiome data

The human microbiome can contribute to pathogeneses of many complex diseases by mediating disease-leading causal pathways. However, standard mediation analysis methods are not adequate to analyze the microbiome as a mediator due to the excessive number of zero-valued sequencing reads in the data that is compounded by its compositional structure. The two main challenges raised by the zero-inflated data structure are: (a) disentangling the mediation effect induced by the point mass at zero; and (b) identifying the observed zero-valued data points that are actually not zero (i.e., false zeros). We develop a novel marginal mediation analysis method under the potential-outcomes framework to fill this gap and show the marginal model can also account for the compositional structure. The mediation effect can be decomposed into two components that are inherent to the two-part nature of zero-inflated distributions. With probabilistic models to account for observing zeros, we also address the challenge with false zeros. A comprehensive simulation study and the application in a real microbiome study showcase our approach in comparison with existing approaches.

stat.ME↗

arXiv2005

Colors of Luminous Bulges in Cluster MS1054-03 and Field Galaxies at Redshifts z ~ 0.83

Using HST images, we separate the bulge-like (pbulge) and disk-like (pdisk) components of 71 galaxies in the rich cluster MS1054-03 and of 21 in the field. Our key finding is that luminous pbulges are very red with restframe U-B ~ 0.45, while predicted colors are bluer by 0.20 mag. Moreover, these very red colors appear to be independent of environment, pbulge luminosity, pdisk color, and pbulge fraction. These results challenge any models of hierarchical galaxy formation that predict the colors of distant (z ~ 0.8) luminous field and cluster bulges would differ. Our findings also disagree with other claims that 30% to 50% of bright bulges and ellipticals at z ~ 1 are very blue (U-B < 0).

astro-ph↗