arXiv subjects

Benjamin Tang

Publications and source records attributed to Benjamin Tang.

3 recordsLinked to original sources

arXiv2025

Endoplasmic Reticulum Structure Determines Optimal Ribosome Density

Recent work has shown an increasing interest in understanding the structure of the endoplasmic reticulum (ER) and how ribosomes are displayed on it. Here we present a model that explains a physical reason for why the cell creates different structures of the ER. Due to the diffusion of biomolecules, we find that flat sheets and a matrix of tubules have different regimes of optimized capture efficiency. We extend the model to explain the observed difference in density of ribosomes on the structures of the ER. Due to the capture efficiency of tubules, less ribosomes are needed on those structures. For flat sheets, more ribosome coverage at biological separation distance is needed to match the same fraction of relative flux. We then push the model to predict that depending on the future life of the translated protein and overall demand for protein expression, the cell will utilize one structure of the ER over another. Predictions are compared with experimental data.

physics.bio-ph↗

arXiv2025

Efficiently Escaping Saddle Points under Generalized Smoothness via Self-Bounding Regularity

We study the optimization of non-convex functions that are not necessarily smooth (gradient and/or Hessian are Lipschitz) using first order methods. Smoothness is a restrictive assumption in machine learning in both theory and practice, motivating significant recent work on finding first order stationary points of functions satisfying generalizations of smoothness with first order methods. We develop a novel framework that lets us systematically study the convergence of a large class of first-order optimization algorithms (which we call decrease procedures) under generalizations of smoothness. We instantiate our framework to analyze the convergence of first order optimization algorithms to first and \textit{second} order stationary points under generalizations of smoothness. As a consequence, we establish the first convergence guarantees for first order methods to second order stationary points under generalizations of smoothness. We demonstrate that several canonical examples fall under our framework, and highlight practical implications.

math.OC↗

arXiv2024

Glassy Relaxation Dynamics in the Two-Dimensional Heavy Fermion Antiferromagnet CeSiI

The recent discovery of the van der Waals (vdW) layered heavy fermion antiferromagnetic metal CeSiI offers promising potential for achieving accessible quantum criticality in the two-dimensional (2D) limit. CeSiI exhibits both heavy fermion behavior and antiferromagnetic (AFM) ordering, while the exact magnetic structure and phase diagram have yet to be determined. Here, we investigate magnetic properties of atomically thin CeSiI devices with thicknesses ranging from 2-15 vdW layers. The thickness-dependent magnetotransport measurement reveals an intrinsic 2D nature of heavy fermion behavior and antiferromagnetism. Notably, we also find an isotropic, time-dependent hysteresis in both magnetoresistance and Hall resistance, showing glassy relaxation dynamics. This glassy behavior in magnetic structures may suggest the presence of spin glass phases or multipolar ordering, further establishing CeSiI as an intriguing material system for investigating the interplay between magnetic orders and the Kondo effect.

cond-mat.str-el↗