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Biomedical subjects

M J Shaffer

Publications and source records attributed to M J Shaffer.

At least 37 records · Page 2Linked to original sources
PubMedDate not supplied

Simulating interactive effects of symbiotic nitrogen fixation, carbon dioxide elevation, and climatic change on legume growth.

The underlying mechanisms of interaction between the symbiotic nitrogen-fixation process and main physiological processes, such as assimilation, nutrient allocation, and structural growth, as well as effects of nitrogen fixation on plant responses to global change, are important and still open to more investigation. Appropriate models have not been adequately developed. A dynamic ecophysiological model was developed in this study for a legume plant [Glycine max (L.) Merr.] growing in northern China. The model synthesized symbiotic nitrogen fixation and the main physiological processes under variable atmospheric CO2 concentration and climatic conditions, and emphasized the interactive effects of these processes on seasonal biomass dynamics of the plant. Experimental measurements of ecophysiological quantities obtained in a CO2 enrichment experiment on soybean plants, were used to parameterize and validate the model. The results indicated that the model simulated the experiments with reasonable accuracy. The R2 values between simulations and observations are 0.94, 0.95, and 0.86 for total biomass, green biomass, and nodule biomass, respectively. The simulations for various combinations of atmospheric CO2 concentration, precipitation, and temperature, with or without nitrogen fixation, showed that increasing atmospheric CO2 concentration, precipitation, and efficiency of nitrogen fixation all have positive effects on biomass accumulation. On the other hand, an increased temperature induced lower rates of biomass accumulation under semi-arid conditions. In general, factors with positive effects on plant growth tended to promote each other in the simulation range, except the relationship between CO2 concentration and climatic factors. Because of the enhanced water use efficiency with a higher CO2 concentration, more significant effects of CO2 concentration were associated with a worse (dryer and warmer in this study) climate.

Biomass↗
PubMedDate not supplied

Clinical engineering standards, obligations, and accountability.

The growing volume and complexity of biomedical equipment in hospitals are creating legal implications for the clinical engineer. Statutory regulations, court decisions on product liability, and the patient's right to privacy and confidentially affect daily operations. The doctrines of agency, negligence, strict liability, and breach of contract, plus the medical Device Amendments of 1976 to the Federal Food, Drug, and Cosmetic Act, and the Joint Commission on Accreditation of Hospitals' 1976 standards, complicate the conventional clinical engineering functions. The need for the clinical engineer to be alert to his legal obligation is assessed.

Biomedical Engineering↗