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Alterations in trabecular bone were observed in growing male Wistar rats after 18.5 days of orbital flight on the COSMOS 1129 biosatellite. Spaceflight induced a decreased mass of mineralized tissue and an increased fat content of the bone marrow in the proximal tibial and humeral metaphyses. The osteoblast population appeared to decline immediately(More)
A logit model is used to estimate provider choice from six types by malaria patients in rural Nepal. Patient characteristics that influence choice include travel costs, income category, household size, gender, and severity of malaria. Income effects are introduced by assuming the marginal utility of money is a step function of expenditures on the numeraire.(More)
Nested logit is increasingly advocated as a tool of recreational demand and benefit estimation. The intent of this short monograph is to lay out, in a simple fashion, the theory behind the nested-logit model of site choice and the nested-logit model of participation and site choice. Rigorous but straightforward derivations of the properties of nested-logit(More)
Estimating a demand system under the assumption that preferences are homogeneous may lead to biased estimates of parameters for any specific individual and significantly different expected consumer surplus estimates. This paper investigates several different parametric methods to incorporate heterogeneity in the context of a repeated discrete-choice model.(More)
The acute effects of immobilization on cortical and trabecular bone formation were studied in juvenile male rhesus monkeys (Macaca mulatta). Four animals were immobilized for two weeks by application of total body casts. Two control monkeys were housed in separate metabolic cages under similar environmental and dietary conditions. Tetracycline derivatives(More)
Male Wistar rats were placed in orbit for 18.5 days aboard the Soviet COSMOS 1129 biological satellite. Tetracycline was administered before and after spaceflight to label areas of bone formation. An inhibition of periosteal bone formation occurred during spaceflight in the tibial and humeral diaphyses, but this defect was corrected during the postflight(More)
A hypokinetic model has been developed which attempts to simulate the weightlessness experienced during space flight. Male rats (approximately 130 g) were suspended from the model with a head-down tilt for a two-week period. Total mechanical unloading of the hind limbs and partial unloading of the fore limbs occurred. In comparison to pair-fed control rats,(More)