19,205 research outputs found
Effects of MDMA on body temperature in humans
Hyperthermia is a severe complication associated with the recreational use of 3,4-methylenedioxymethamphetamine(MDMA, Ecstasy). In this review, the clinical laboratory studies that tested the effects of MDMA on body temperature are summarized. The mechanisms that underlie the hyperthermic effects of MDMA in humans and treatment of severe hyperthermia are presented. The data show that MDMA produces an acute and dose-dependent rise in core body temperature in healthy subjects. The increase in body temperature is in the range of 0.2-0.8C and does not result in hyperpyrexia (>40C) in a controlled laboratory setting. However, moderately hyperthermic body temperatures >38.0C occur frequently at higher doses, even in the absence of physical activity and at room temperature. MDMA primarily releases serotonin and norepinephrine. Mechanistic clinical studies indicate that the MDMA-induced elevations in body temperature in humans partially depend on the MDMA-induced release of norepinephrine and involve enhanced metabolic heat generation and cutaneous vasoconstriction, resulting in impaired heat dissipation. The mediating role of serotonin is unclear. The management of sympathomimetic toxicity and associated hyperthermia mainly includes sedation with benzodiazepines and intravenous fluid replacement. Severe hyperthermia should primarily be treated with additional cooling and mechanical ventilation
Schematic models for dynamic yielding of sheared colloidal glasses
The nonlinear rheological properties of dense suspensions are discussed
within simplified models, suggested by a recent first principles approach to
the model of Brownian particles in a constant-velocity-gradient solvent flow.
Shear thinning of colloidal fluids and dynamical yielding of colloidal glasses
arise from a competition between a slowing down of structural relaxation,
because of particle interactions, and enhanced decorrelation of fluctuations,
caused by the shear advection of density fluctuations. A mode coupling approach
is developed to explore the shear-induced suppression of particle caging and
the resulting speed-up of the structural relaxation.Comment: 33 pages, 10 figures; accepted for publication in Faraday Disc. 123
(2002); small numerical correction
Partitions with fixed differences between largest and smallest parts
We study the number of partitions of with difference between
largest and smallest parts. Our main result is an explicit formula for the
generating function . Somewhat
surprisingly, is a rational function for ; equivalently,
is a quasipolynomial in for fixed . Our result generalizes to
partitions with an arbitrary number of specified distances.Comment: 5 page
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