Comparison of experimental and numerical studies of ionizing flow over a cylinder

Comparisons are made between experimental measurements and numerical simulations of ionizing flows generated in a superorbital facility. Nitrogen, with a freestream velocity of around 10 km/s, was passed over a cylindrical model, and images were recorded using two-wavelength holographic interferometry. The resulting density, electron concentration, and temperature maps were compared with numerical simulations from the Langley Research Center aerothermodynamic upwind relaxation algorithm. The results showed generally good agreement in shock location and density distributions. Some discrepancies were observed for the electron concentration, possibly, because simulations were of a two-dimensional flow, whereas the experiments were likely to have small three-dimensional effects.

The effects of predator odors in mammalian prey species: A review of field and laboratory studies

wPrey species show specific adaptations that allow recognition, avoidance and defense against predators. For many mammalian species this includes sensitivity towards predator-derived odors. The typical sources of such odors include predator skin and fur, urine, feces and anal gland secretions. Avoidance of predator odors has been observed in many mammalian prey species including rats, mice, voles, deer, rabbits, gophers, hedgehogs, possums and sheep. Field and laboratory studies show that predator odors have distinctive behavioral effects which include (1) inhibition of activity, (2) suppression of non-defensive behaviors such as foraging, feeding and grooming, and (3) shifts to habitats or secure locations where such odors are not present. The repellent effect of predator odors in the field may sometimes be of practical use in the protection of crops and natural resources, although not all attempts at this have been successful. The failure of some studies to obtain repellent effects with predator odors may relate to (1) mismatches between the predator odors and prey species employed, (2) strain and individual differences in sensitivity to predator odors, and (3) the use of predator odors that have low efficacy. In this regard, a small number of recent studies have suggested that skin and fur-derived predator odors may have a more profound lasting effect on prey species than those derived from urine or feces. Predator odors can have powerful effects on the endocrine system including a suppression of testosterone and increased levels of stress hormones such as corticosterone and ACTH. Inhibitory effects of predator odors on reproductive behavior have been demonstrated, and these are particularly prevalent in female rodent species. Pregnant female rodents exposed to predator odors may give birth to smaller litters while exposure to predator odors during early life can hinder normal development. Recent research is starting to uncover the neural circuitry activated by predator odors, leading to hypotheses about how such activation leads to observable effects on reproduction, foraging and feeding. (c) 2005 Elsevier Ltd. All rights reserved.

Free radicals in alcoholic myopathy: Indices of damage and preventive studies

Chronic alcoholic myopathy affects up to two-thirds of all alcohol misusers and is characterized by selective atrophy of Type If (glycolytic, fast-twitch, anaerobic) fibers. In contrast, the Type I fibers (oxidative, slow-twitch, aerobic) are relatively protected. Alcohol increases the concentration of cholesterol hydroperoxides and malondialdehyde-protein adducts, though protein-carbonyl concentration levels do not appear to be overtly increased and may actually decrease in some studies. In alcoholics, plasma concentrations of a-tocopherol may be reduced in myopathic patients. However, a-tocopherol supplementation has failed to prevent either the loss of skeletal muscle protein or the reductions in protein synthesis in alcohol-dosed animals. The evidence for increased oxidative stress in alcohol-exposed skeletal muscle is thus inconsistent. Further work into the role of ROS in alcoholic myopathy is clearly warranted. (C) 2002 Elsevier Science Inc.

Antipodas: Journal of Hispanic and Galician Studies

Special title: De La Mancha a Nueva Nurcia. Imágenes de identidad en viejos y nuevos mundos: From La Mancha to New Nurcia. Images of identity in old and new worlds. In memory of Ben Haneman, doctor of medicine and friend, who contributed to the spread of quixotic ideals in Australia.

An evolutionary framework for studies of hibernation and short-term torpor

Data from diverse studies endorse ideas that short term torpor and hibernation are expressions of ancient characters. In evolutionary terms, their basic mechanisms are probably plesiomorphic (= ancestral/primitive) and physiologically similar. This contrasts with the alternate view that they are apomorphic (= derived, specialized), arising independently in many taxa from homeothermic ancestry by numerous apparent convergences. This paper explores some of the implications of accepting the plesiomorphic interpretation. Hibernation is, of course, a complex phenomenon that has undergone variations and refinements in different mammalian lineages. The argument is not that hibernation in total is a plesiomorphic character, but that it is built upon fundamental processes that are. Taking this view provides a framework for research that emphasizes the value of comparative studies, particularly of reptiles and birds. Studies of reptiles, for example, might unravel the mystery about periodic arousals. A plesiomorphic framework also explains the most extreme examples of hibernation as derived specializations from ancestry in which heterothermy is more about energy management than escape from cold. It cautions against using low body temperature (Tb) alone to diagnose torpor, emphasizes the need to distinguish between constitutional eurythermy (plesiomorphic) and constitutional stenothermy (apomorphic), and leads to a parsimonious theory about the evolution of endothermy. The paper proposes that brown adipose tissue (BAT) is apomorphic within eutheria and highlights the conundrum posed by the occurrence of both nonshivering thermogenesis (NST) and rapid arousal from hibernation in noneutherian mammals that lack BAT and uncoupling protein 1 (UCP1). It endorses the likely existence of a different, ancient and widespread mechanism for regulatory NST in mammals.