arXiv subjects

Vedant Sachdeva

Publications and source records attributed to Vedant Sachdeva.

5 recordsLinked to original sources

arXiv2022

Learning to learn: Non-equilibrium design protocols for adaptable materials

Evolution in time-varying environments naturally leads to adaptable biological systems that can easily switch functionalities. Advances in the synthesis of environmentally-responsive materials therefore open up the possibility of creating a wide range of synthetic materials which can also be trained for adaptability. We consider high-dimensional inverse problems for materials where any particular functionality can be realized by numerous equivalent choices of design parameters. By periodically switching targets in a given design algorithm, we can teach a material to perform incompatible functionalities with minimal changes in design parameters. We exhibit this learning strategy for adaptability in two simulated settings: elastic networks that are designed to switch deformation modes with minimal bond changes; and heteropolymers whose folding pathway selections are controlled by a minimal set of monomer affinities. The resulting designs can reveal physical principles, such as nucleation-controlled folding, that enable adaptability.

cond-mat.soft↗

arXiv2021

Inferring couplings in networks across order-disorder phase transitions

Statistical inference is central to many scientific endeavors, yet how it works remains unresolved. Answering this requires a quantitative understanding of the intrinsic interplay between statistical models, inference methods and data structure. To this end, we characterize the efficacy of direct coupling analysis (DCA)--a highly successful method for analyzing amino acid sequence data--in inferring pairwise interactions from samples of ferromagnetic Ising models on random graphs. Our approach allows for physically motivated exploration of qualitatively distinct data regimes separated by phase transitions. We show that inference quality depends strongly on the nature of generative models: optimal accuracy occurs at an intermediate temperature where the detrimental effects from macroscopic order and thermal noise are minimal. Importantly our results indicate that DCA does not always outperform its local-statistics-based predecessors; while DCA excels at low temperatures, it becomes inferior to simple correlation thresholding at virtually all temperatures when data are limited. Our findings offer new insights into the regime in which DCA operates so successfully and more broadly how inference interacts with data structure.

physics.bio-ph↗

arXiv2019

Tuning environmental timescales to evolve and maintain generalists

Natural environments can present diverse challenges, but some genotypes remain fit across many environments. Such `generalists' can be hard to evolve, out-competed by specialists fitter in any particular environment. Here, inspired by the search for broadly-neutralising antibodies during B-cell affinity maturation, we demonstrate that environmental changes on an intermediate timescale can reliably evolve generalists, even when faster or slower environmental changes are unable to do so. We find that changing environments on timescales comparable to evolutionary transients in a population enhances the rate of evolving generalists from specialists, without enhancing the reverse process. The yield of generalists is further increased in more complex dynamic environments, such as a `chirp' of increasing frequency. Our work offers design principles for how non-equilibrium fitness `seascapes' can dynamically funnel populations to genotypes unobtainable in static environments.

q-bio.PE↗

arXiv2016

Hemoglobin Strain Field Waves and Allometric Functionality

Hemoglobin (Hgb) forms tetramers (dimerized dimers), which enhance its globular stability and may also facilitate small gas molecule transport, as shown by recent all-atom Newtonian solvated simulations. Hydropathic bioinformatic scaling reveals many wave-like features of strained Hgb structures at the coarse-grained amino acid level, while distinguishing between these features thermodynamically. Strain fields localized near hemes interfere with extended strain fields associated with dimer interfacial misfit, resulting in wave-length dependent dimer correlation function antiresonances.

q-bio.BM↗

arXiv2016

Oxygen Channels and Fractal Wave-Particle Duality in the Evolution of Myoglobin and Neuroglobin

The evolution of terrestrial and aquatic wild type (WT) globins is dominated by changes in two proximate - distal Histidine ligand exit channels, here monitored quantitatively by hydropathic waves. These waves reveal allometric functional features inaccessible to single amino acid stereochemical contact models, and even very large all-atom Newtonian simulations. The evolutionary differences between these features between myoglobin and neuroglobin are related to the two oxidation channels through hydropathic wave analysis, which identifies subtle interspecies functional differences inaccessible to traditional size and metabolic scaling studies. Our analysis involves dynamic synchronization of allometric interactions across entire globins.

q-bio.OT↗