2,845 research outputs found

    Jupiter's polar ionospheric flows: measured intensity and velocity variations poleward of the main auroral oval

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    Recent analysis of high-resolution spectra of Doppler-shifted H3+ emission from the auroral/polar regions of Jupiter revealed a complex wind system, with a persistent auroral electrojet and strong anti-sunward flows in a region of lesser intensity centred around the magnetic pole [ Stallard et al., 2001 ]. This region, which we have called the Dark Polar Region (DPR), is re-investigated, transforming the observed line-of-sight velocities into a frame of reference fixed with respect to the magnetic pole. The DPR is shown to include a region essentially stagnant in this frame of reference (the f-DPR). We identify it as a region coupled to open magnetotail field lines. There is also a transition region in which the ion velocity returns to corotation (the r-DPR)

    Letter to Dr. H.A. Morgan from E.J. Miller, Editor

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    Toward a Cosmological Dual to Inflation

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    We derive all single-field cosmologies with unit sound speed that generate scale invariant curvature perturbations on a dynamical attractor background. We identify three distinct phases: slow-roll inflation; a slowly contracting adiabatic ekpyrotic phase, described by a rapidly varying equation of state; and a novel adiabatic ekpyrotic phase on a slowly expanding background. All of these yield identical power spectra. The degeneracy is broken at the 3-point level: unlike the nearly Gaussian spectrum of slow-roll inflation, adiabatic ekpyrosis predicts large non-Gaussianities on small scales

    STAT5a/b contribute to sex bias in vascular disease: A neuroendocrine perspective

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    Previous studies have elucidated a neuroendocrine mechanism consisting of the hypothalamus (growth hormone releasing hormone, GHRH) – pituitary (growth hormone, GH) – STAT5a/b axis that underlies sex-biased gene expression in the liver. It is now established that male vs female patterned secretion of GHRH, and thus of circulating GH levels (“pulsatile” vs “more continuous” respectively), leading to differently patterned activation of PY-STAT5a/b in hepatocytes results in sex-biased gene expression of cohorts of hundreds of downstream genes. This review outlines new data in support of a STAT5a/b-based mechanism of sex bias in the vascular disease pulmonary hypertension (PH). Puzzling observations in PH include its 2-4-fold higher prevalence in women but a male-dominance in many rodent models, and, paradoxically, inhibition of PH development by estrogens in such models. We observed that conditional deletion of STAT5a/b in vascular smooth muscle cells (SMC) in mice converted the male-dominant model of chronic hypoxia-induced PH into a female-dominant phenotype. In human idiopathic PH, there was reduced STAT5a/b and PY-STAT5 in cells in late-stage obliterative pulmonary arterial lesions in both men and women. A juxtaposition of the prior liver data with the newer PH-related data drew attention to the hypothalamus-GH-STAT5 axis, which is the major target of estrogens at the level of the hypothalamus. This hypothesis explains many of the puzzling aspects of sex bias in PH in humans and rodent models. The extension of STAT5-anchored mechanisms of sex bias to vascular disease emphasizes the contribution of central neuroendocrine processes in generating sexual dimorphism in different tissues and cell types

    Dual-energy X-ray absorptiometry scans accurately predict differing body fat content in live sheep

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    Background There is considerable interest in implementing mobile scanning technology for on-farm body composition analysis on live animals. These experiments evaluated the use of dual energy X-ray absorptiometry (DXA) as an accurate method of total body fat measurement in live sheep. Results In Exp. 1, visceral and whole body fat analysis was undertaken in sheep with body condition scores (BCS) in the range 2 to 3.25 (scale 1: thin to 5: fat). The relationship of BCS was moderately correlated with visceral fat depot mass (r = 0.59, P  0.05, n = 9). There was a moderate correlation between DXA body fat and BCS (r = 0.70, P < 0.01, n = 17), and DXA body fat was highly correlated with chemical body fat (r = 0.81, P < 0.001, n = 9). In Exp. 3, a series of five DXA scans, at 8-week intervals, was performed on growing sheep over a 32-week period. The average BCS ranged from 2.39 ± 0.07 (S.E.M.) to 3.05 ± 0.11 and the DXA body fat (%) ranged from 16.8 ± 0.8 to 24.2 ± 1.2. There was a moderate correlation between DXA body fat and BCS over the 32 weeks (r = 0.61, P < 0.001, n = 24). Conclusions Overall, these experiments indicated that there was good agreement between BCS, DXA and chemical analysis for measuring total body fat in sheep, and that DXA scanning is a valid method for longitudinal measurement of total body fat in live sheep

    Animal welfare indicators for sheep during sea transport: The effect of voyage day and time of day

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    Ensuring the well-being of animals during transport is becoming an increasingly important societal concern. The Australian livestock export industry recognises the need for comprehensive monitoring and reporting on animal welfare during sea transport. It is predicted that pen-side assessments of sheep can be used to monitor environmental conditions, resource access, and animal health and behavioural outcomes throughout a sea voyage. Pen-side assessments by observation are non-invasive and practical to apply in an industry setting. This study monitored sheep using a pilot list of welfare indicators during two sea voyages from Australia to the Middle East, in contrasting seasons. Sheep behaviour, environment and resources were recorded three times daily via pen-side observations of six pens of Merino wethers (castrated males), repeated over three decks for each voyage. Behavioural outcomes were examined for the effect of sampling frequency on group assessments. The number of behavioural measures were reduced via Principal Component (PC) analysis. The primary three PC factors were tested against the time of sampling and pen location after accounting for the effect of environmental- and resource-based predictor variables. PC 1 (24.0 % of the total variance) described activity levels, with sheep on Voyage B being more active in the morning and resting or recumbent in the middle of the afternoon and evening. PC 2 (14.7 %) reflected heat responses with the majority of the variation in these data accounted for by changes in Wet Bulb Globe Temperature (WBGT) and manure pad moisture. The heat responses described by PC 2 also varied by voyage day (p < 0.001) and time point (p < 0.001). PC 3 scores (9.5 %) reflected flight distances and feeding behaviour and strongly correlated to WBGT and pellet consumption per head per day. Feeding behaviour generally became more competitive, and flight distances reduced as both voyages progressed. Results indicate that a comprehensive welfare monitoring protocol requires repeated daily sampling throughout a voyage. The findings of this study are pertinent for developing a sampling strategy to assess sheep welfare during sea transport

    Absence of a dose-rate effect in the transformation of C3H 10T1/2 cells by α-particles

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    The findings of Hill et al. (1984) on the greatly enhanced transformation frequencies at very low dose rates of fission neutrons induced us to perform an analogous study with -particles at comparable dose rates. Transformation frequencies were determined with γ-rays at high dose rate (0·5 Gy/min), and with -particles at high (0·2 Gy/min) and at low dose rates (0·83-2·5 mGy/min) in the C3H 10T1/2 cell system. α-particles were substantially more effective than γ-rays, both for cell inactivation and for neoplastic transformation at high and low dose rates. The relative biological effectiveness (RBE) for cell inactivation and for neoplastic transformation was of similar magnitude, and ranged from about 3 at an -particle dose of 2 Gy to values of the order of 10 at 0·25 Gy. In contrast to the experiments of Hill et al. (1984) with fission neutrons, no increased transformation frequencies were observed when the -particle dose was protracted over several hours

    Conformationally restricted calpain inhibitors

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    The cysteine protease calpain-I is linked to several diseases and is therefore a valuable target for inhibition. Selective inhibition of calpain-I has proved difficult as most compounds target the active site and inhibit a broad spectrum of cysteine proteases as well as other calpain isoforms. Selective inhibitors might not only be potential drugs but should act as tools to explore the physiological and pathophysiological roles of calpain-I. α-Mercaptoacrylic acid based calpain inhibitors are potent, cell permeable and selective inhibitors of calpain-I and calpain-II. These inhibitors target the calcium binding domain PEF(S) of calpain-I and -II. Here X-ray diffraction analysis of co-crystals of PEF(S) revealed that the disulfide form of an α-mercaptoacrylic acid bound within a hydrophobic groove that is also targeted by a calpastatin inhibitory region and made a greater number of favourable interactions with the protein than the reduced sulfhydryl form. Measurement of the inhibitory potency of the α-mercaptoacrylic acids and X-ray crystallography revealed that the IC50 values decreased significantly on oxidation as a consequence of the stereo-electronic properties of disulfide bonds that restrict rotation around the S–S bond. Consequently, thioether analogues inhibited calpain-I with potencies similar to those of the free sulfhydryl forms of α-mercaptoacrylic acids

    Suspended particulate matter dynamics in coastal waters from ocean color: Application to the northern Gulf of Mexico

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    Suspended particulate matter (SPM) plays an important role in primary production, pollutant transport, and other biogeochemical processes in coastal marine environments. We present an empirical two-band ocean color remote sensing reflectance algorithm (Rrs670/ Rrs555) for SPM concentrations developed using field measurements obtained in coastal waters influenced by the Mississippi River in 2000, 2002, and 2004. The ratio algorithm was also found to be highly correlated to backscattering coefficient (bbp(555), r2 = 0.96), the backscattering ratio (bbp(555) /bp(555), r2 = 0.82) and the spectral backscattering slope (γ, r2 = 0.72) in March 2002, a period with large hydrographic variability in the study area. Strong correlations between water column bbp(555), SPM and nonalgal absorption anap(443) suggest the dominant influence of nonalgal particles on bbp. Sea WiFS derived SPM and γ distributions indicated event-based variability linked to energetic disturbances such as frontal passages, resuspension, and river discharge that with bbp/bp could reveal refractive index and particle size characteristics in the coastal environment
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