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Biomedical subjects

B Gavish

Publications and source records attributed to B Gavish.

24 records · Page 2Linked to original sources
PubMedDate not supplied

Monitoring of erythrocyte aggregate morphology under flow by computerized image analysis.

The morphology of red blood cell (RBC) aggregates was studied by direct visualization of RBC aggregation at different flow conditions in a computerized image analyzer. The aggregate morphology is expressed by an Aggregate Shape Parameter (ASP), defined as the ratio of the aggregate projected area to its square perimeter. Aggregation was induced by either dextran-70 (m.w. 70,000) or dextran-500 (m.w. 500,000), and compared to that in plasma. It was found that the aggregate morphology is a characteristic of the aggregating agent--in dextran-500, the RBC form rouleau aggregates as in plasma, while in dextran-70, they form clusters. In each system, while maintaining the overall typical morphology, the ASP decreases (i.e., the aggregate becomes longer) as the aggregate size is increased. The distribution of the ASP as a function of the aggregate size remains unchanged when the aggregate size is changed by modulation of the dextran concentration or the shear stress. Stretching of a rouleau aggregate by application of shear stress is reflected by a corresponding change in the ASP. It is suggested that the ASP is a characteristic of intercellular interactions. A theoretical model is proposed for evaluation of the deviation of aggregate shape from that of rouleau structure.

Erythrocyte Aggregation↗
PubMedDate not supplied

E-approximations for multidimensional weighted location problems.

This paper considers the multidimensional weighted minimax location problem, namely, finding a facility location that minimizes the maximal weighted distance to n points. General distance norms are used. An epsilon-approximate solution is obtained by applying a variant of the Russian method for the solution of Linear Programming. The algorithm has a time complexity of O(n log epsilon) for fixed dimensionality k. Computational results are presented.

Catchment Area, Health↗
PubMedDate not supplied

Plethysmographic characterization of vascular wall by a new parameter--minimum rise-time: age dependence in health.

Analysis of the plethysmographic pulse volume contour in terms of "crest time", made in 1940-1960, revealed age dependence and clinically significant variations between health and disease, including arteriosclerosis, hypertension and various dermatoses. A new parameter--"minimum rise-time" (MRT) is suggested and defined from pulse volume contour. In health it was found to be age dependent using finger photoplethysmography. The MRT of the pulse volume is shown by a model 1) to be associated with the mechanical properties (viscoelasticity) of the vascular wall, 2) to approximate the MRT of the pulse pressure, and 3) to be free of ambiguities found in "crest time" and "half rise-time" previously used. The analysis suggests that the gradient of the MRT along peripheral vessels might be a clinical indication of variations in the mechanical properties of the vascular wall.

Adolescent↗