17 research outputs found
Neutron star envelopes and thermal radiation from the magnetic surface
The thermal structure of neutron star envelopes is discussed with emphasis on analytic results. Recent progress on the effect of chemical constitution and high magnetic fields on the opacities and the thermal structure is further reviewed in view of the application to pulsar cooling and magnetars
The recycling of carbon in glucose, lactate and alanine in sheep
Pregnant ewes with catheters implanted in an artery and the uterine and recurrent tarsal veins were infused at a constant rate with UâÂčâŽC-labelled glucose, alanine or bicarbonate. Measurements were made of the overall and local fractional contribution of glucose and alanine to COâ production and of the extent of interconversion of these metabolites. In the whole animal, by coupling the results with the authorsâ previous study of lactate metabolism, a solution was obtained to an open unrestricted 4-compartment model of the exchange of carbon between glucose, lactate, alanine and COâ. A more limited study was made with non-pregnant sheep because complete data for lactate interactions with alanine were not available. Our analysis of glucose/lactate/alanine/COâ interactions in pregnant sheep suggests that about two-thirds of the glycogenic carbon was oxidised fairly directly to COâ. There was relatively little recycling of glucose carbon through lactate and alanine so that most of the remaining glycogenic carbon was stored as product with relatively long turnover time. It is possible that much of this was in the form of muscle glycogen, and analysis of glycogenic carbon exchange across the hind limb muscle was consistent with this conclusion. In non-pregnant ewes, the findings, although incomplete, suggested that there were no great differences from the findings in pregnant ewes.Derek B. Lindsay, Patrick J. Barker, Andrew J. Northrop, Brian P. Setchell, Graham J. Faichne
Heat alleviation strategies for athletic performance: a review and practitioner guidelines
International competition inevitably presents logistical challenges for athletes. Events such as the Tokyo 2020 Olympic Games, require further consideration given weather forecasts suggest athletes will experience significant heat stress. Given the expected climate, athletes face major challenges to health and performance. With this in mind, heat alleviation strategies should be a fundamental consideration. This review provides a focused perspective of the relevant literature describing how practitioners can structure male and female athlete preparations for performance in hot, humid conditions. Whilst scientific literature commonly describes experimental work, with a primary focus on maximising magnitudes of adaptive responses, this may sacrifice ecological validity, particularly for athletes whom must balance logistical considerations aligned with integrating environmental preparation around training, tapering and travel plans. Additionally, opportunities for sophisticated interventions may not be possible in the constrained environment of the athlete village or event arenas. This review therefore takes knowledge gained from robust experimental work, interprets it and provides direction on how practitioners/coaches can optimise their athletesâ heat alleviation strategies. This review identifies two distinct heat alleviation themes that should be considered to form an individualised strategy for the athlete to enhance thermoregulatory/performance physiology. First, chronic heat alleviation techniques are outlined, these describe interventions such as heat acclimation, which are implemented pre, during and post-training to prepare for the increased heat stress. Second, acute heat alleviation techniques that are implemented immediately prior to, and sometimes during the event are discussed