Biomedical subjects

A Houshyar

Publications and source records attributed to A Houshyar.

3 recordsLinked to original sources

PubMed1991

Transient behavior of a stochastic process for screening progressive diseases.

This paper extends a mathematical model developed by the authors for describing the stochastic process underlying the etiology of non-contagious progressive diseases. For a population with no prior history of scheduled screening, the number of undetected and detected diseased individuals in the population under an established screening policy is used to calculate the expected total screening cost at any given time during the transient period of the associated stochastic process. A graphical representation of our model shows the status of different subgroups of a particular age group at any time T, and provides a clear summary of the expected number of individuals whose disease remains undetected.

Mass Screening↗

PubMed1990

Physiological and psychophysical responses to static, dynamic and combined arm tasks.

The main objective of the present study was to determine the effects of arm tasks possessing varying degrees of static and dynamic components upon the physiological and psychophysical strain imposed on the human body. Heart rate and blood pressure were used as indices of cardiovascular strain, while ratings of perceived exertion and endurance time are used as indices of psychophysical strain. For each weight of load studied, static tasks recorded the highest systolic blood pressure, dyastolic pressure, and ratings of perceived exertion values followed by combined, then highly dynamic, tasks. The highly dynamic task recorded the highest endurance time followed by combined then purely static tasks. This study supports the idea that blood pressure should be incorporated as one of the monitored strain factors in setting criteria for manual materials-handling tasks. In addition, the ratings of perceived exertion can be used as an effective tool in assessing the static component of the task. Based on the results obtained from the experimental conditions studied, the weight of the load has been shown to be an important parameter in the design of arm tasks comprising varying degrees of static and dynamic components. On the other hand, the frequency of handling is not an important parameter in the design of these types of tasks.

Journal Article↗

PubMed1990

A mathematical model for scheduling screening tests for progressive diseases.

In this paper, a mathematical model describing the stochastic process underlying the etiology of noncontagious, curable, progressive diseases is developed. In our previous study of progressive diseases, the reliabilities of screening tests were assumed to be constants, independent of how long the individual has had the disease. The purpose of this study is to develop more insight into modeling the disease process, and the interaction of screening tests with the natural behavior of the disease. To accomplish this task, more realistic screening parameters are selected, and optimum policies for mass screening programs under different reliabilities of screening tests are developed. These modifications make the model general enough to be applicable to a larger class of progressive diseases that includes breast cancer. Solutions to two simplified versions of the model for childhood neuroblastoma illustrate the use of our proposed procedure.

Catastrophic Illness↗