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Biomedical subjects

M Jarrah

Publications and source records attributed to M Jarrah.

6 recordsLinked to original sources
PubMed1997

Human body model response to mechanical impulse.

Despite our understanding of the importance of falling, previous studies have ignored the effects of falls from standing height. In this article, lumped parameter linear and nonlinear models of a standing human have been used to simulate the impact response of the body segments due to inputs at the shoes. The acceleration transfer and frequency response were determined. The effect of nonlinear damping was simulated. Nonlinear effects were found to be most significant when the input amplitude increases. Frequency response attenuation was significant, resulting in almost a shift in the magnitude plots in the range (0.1-100 Hz) of frequency. When the input amplitude was reduced, the nonlinear effects became apparent only in the medium frequency range. In the case simulating a human subject exposed to impulse at the foot, a large amount of energy is dissipated in the joints due to the friction resulting in a joint disorder. This is most significant at the medium frequency range that is expected to be induced by a running human subject.

Biomechanical Phenomena↗
PubMed1979

Synchronous aortofemoral or iliofemoral bypass with revascularization of the lower extremity.

Bypassing aortoiliac stenosing lesions to the profunda femoria alone, even with extensive end-arterectomy and angioplasty of the latter, will not provide predictable excellent results in the presence of gangrene and occlusion in the femoral popliteal system. With severe pregangrene and rest pain, residual ischemic complaints are also common, and if lesions are present, healing is incomplete or, at best, delayed. Alternatively, femoropopliteal or tibial bypass, in the presence of even moderately diminished inflow, is subject to either early or delayed closure, unless proximal repair is also performed in appropriately selected patients. Synchronous correction of tandem lesions involving the aortoiliac and femoropopliteal segments should, therefore, be considered for limb salvage only and particularly in the presence of focal gangrene, excision or debridement of which can be anticipated to heal after successful bypass. Major diminution in femoral inflow usually indicates the need for proximal repair only, even in the presence of distal lesions. Noninvasive studies and intraoperative flow determinations are not uniformly helpful in patient selection. Synchronous aortofemoral or iliofemoral and femoropopliteal or tibial reconstructions were performed upon 38 patients, 15 of whom had no prior vascular operation and 23 of whom had previously undergone either aortofemoral or femoropopliteal bypasses that had failed. Graft patency for all patients was 76 per cent, and although it was better for the patients in group 1 than for those in group 2, no statistical significance existed between the two groups. Improved patient selection and criteria for performing synchronous reconstructions might originally have been of benefit for the patients in group 2, avoiding more difficult secondary repairs. It must be emphasized, however, that synchronous reconstructions should not be done routinely in the presence of multilevel disease. Rather, specific indications do exist and should be considered on an individual basis.

Aged↗
PubMedDate not supplied

Heart response to horizontal impulse.

Lumped body parameters linear and nonlinear models have been developed and used for the analysis of the response of the heart in a seated human body due to impulsive horizontal inputs at various body segments. The acceleration transfer magnitude and phase due to impulsive inputs at various body segments are reported. Time histories of the heart acceleration transfer were obtained for both linear and nonlinear models. The results indicate that the largest acceleration transfer occurs at 2-3 Hz frequency. Inputs at the upper body segments excite a second peak and in the acceleration transfer at 10-12 Hz. The nonlinear model shows large attenuation at the high frequency range (larger than 10 Hz) and less attenuation at the 1-5 Hz frequency range.

Abdomen↗