Date of Award

Spring 2008

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Electrical & Computer Engineering

Program/Concentration

Electrical Engineering

Committee Director

Ravindra P. Joshi

Committee Member

Linda L. Vahala

Committee Member

Sachin Shetty

Call Number for Print

Special Collections LD4331.E55 G328 2008

Abstract

Statistical computations are an important tool for the analysis of stochastic phenomena and processes that are characterized by variability. Biological systems (e.g., cells, tissues etc.) are perfect examples wherein response to a given external stimulus can be varied and needs to be adequately considered. The Monte Carlo method of analysis has now been recognized as the most effective way of treating stochastic variability.

This thesis uses Monte Carlo based simulations to probe two problems that require the quantification and modeling of effects caused by energy deposition onto biological matter from external sources. One problem involves the probabilistic study of the potential biological risk factors arising from cosmic and space radiation during space missions. The second problem is the prediction of cell survival in response to a train of externally applied electric pulses. The first task set forth in this thesis is the development of a Graphical User Interface (GUI) for the assessment of various stochastic factors affecting the uncertainties in risk estimation from outer space radiation. The GUI developed here incorporates data collected from research at NASA and includes the risk coefficients specified therein. It uses Normal, Lognormal and Polynomial distributions specified for the various risk factors. The GUI is capable of performing Monte Carlo calculations based on combinations of these distributions. Results of the simulations can be displayed, plotted and analyzed.

The second task carried out in this thesis is the time-dependent, Markovian modeling of birth-death-repair responses of cells subjected to a train of electric pulses. The focus was on developing a model that would predict the cell survivability as a function of time, following such external pulsing. The concepts of target theory (as first proposed in the context of ionizing radiation) have been applied for the analysis and survivability predictions. The dependence of the survivability results on the applied voltage (i.e., electric field), the number of pulses (i.e., the total energy deposition), and recovery rates from electrical injury are naturally included in this approach. The numerical model implementation, upon its development, has successfully been carried out through a Monte Carlo scheme that tracks cell health as a function of time. Very good agreement between model survivability predictions with actual experimental data has been obtained, thus validating the present approach.

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DOI

10.25777/6p46-qz76

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