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Physical Sciences and Mathematics Commons

Open Access. Powered by Scholars. Published by Universities.®

Applied Mathematics

2012

William & Mary

Arts & Sciences Articles

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Full-Text Articles in Physical Sciences and Mathematics

Discrete-State Stochastic Models Of Calcium-Regulated Calcium Influx And Subspace Dynamics Are Not Well-Approximated By Odes That Neglect Concentration Fluctuations, Seth H. Weinberg, Gregory D. Smith Dec 2012

Discrete-State Stochastic Models Of Calcium-Regulated Calcium Influx And Subspace Dynamics Are Not Well-Approximated By Odes That Neglect Concentration Fluctuations, Seth H. Weinberg, Gregory D. Smith

Arts & Sciences Articles

Cardiac myocyte calcium signaling is often modeled using deterministic ordinary differential equations (ODEs) and mass-action kinetics. However, spatially restricted “domains” associated with calcium influx are small enough (e.g., 10−17 liters) that local signaling may involve 1–100 calcium ions. Is it appropriate to model the dynamics of subspace calcium using deterministic ODEs or, alternatively, do we require stochastic descriptions that account for the fundamentally discrete nature of these local calcium signals? To address this question, we constructed a minimal Markov model of a calcium-regulated calcium channel and associated subspace. We compared the expected value of fluctuating subspace calcium concentration (a result …


Generating A Close-To-Reality Synthetic Population Of Ghana, Tyler Frazier, Andreas Alfons Jan 2012

Generating A Close-To-Reality Synthetic Population Of Ghana, Tyler Frazier, Andreas Alfons

Arts & Sciences Articles

The purpose of this research is to generate a close-to-reality synthetic human population for use in a geosimulation of urban dynamics. Two commonly accepted approaches to generating synthetic human populations are Iterative Proportional Fitting (IPF) and Resampling with Replacement. While these methods are effective at reproducing one instance of the probability model describing the survey, it is an instance with extremely small variability amongst subgroups and is very unlikely to be the real population. IPF and Resampling with Replacement also rely on pure replication of units from the underlying sample which can increase unrealistic model behavior. In this work we …