10,720 research outputs found

    User data dissemination concepts for earth resources

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    Domestic data dissemination networks for earth-resources data in the 1985-1995 time frame were evaluated. The following topics were addressed: (1) earth-resources data sources and expected data volumes, (2) future user demand in terms of data volume and timeliness, (3) space-to-space and earth point-to-point transmission link requirements and implementation, (4) preprocessing requirements and implementation, (5) network costs, and (6) technological development to support this implementation. This study was parametric in that the data input (supply) was varied by a factor of about fifteen while the user request (demand) was varied by a factor of about nineteen. Correspondingly, the time from observation to delivery to the user was varied. This parametric evaluation was performed by a computer simulation that was based on network alternatives and resulted in preliminary transmission and preprocessing requirements. The earth-resource data sources considered were: shuttle sorties, synchronous satellites (e.g., SEOS), aircraft, and satellites in polar orbits

    User data dissemination concepts for earth resources: Executive summary

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    The impact of the future capabilities of earth-resources data sensors (both satellite and airborne) and their requirements on the data dissemination network were investigated and optimum ways of configuring this network were determined. The scope of this study was limited to the continental U.S.A. (including Alaska) and to the 1985-1995 time period. Some of the conclusions and recommendations reached were: (1) Data from satellites in sun-synchronous polar orbits (700-920 km) will generate most of the earth-resources data in the specified time period. (2) Data from aircraft and shuttle sorties cannot be readily integrated in a data-dissemination network unless already preprocessed in a digitized form to a standard geometric coordinate system. (3) Data transmission between readout stations and central preprocessing facilities, and between processing facilities and user facilities are most economically performed by domestic communication satellites. (4) The effect of the following factors should be studied: cloud cover, expanded coverage, pricing strategies, multidiscipline missions

    ACTH and polymorphisms at steroidogenic loci as determinants of aldosterone secretion and blood pressure

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    The majority of genes contributing to the heritable component of blood pressure remain unidentified, but there is substantial evidence to suggest that common polymorphisms at loci involved in the biosynthesis of the corticosteroids aldosterone and cortisol are important. This view is supported by data from genome-wide association studies that consistently link the CYP17A1 locus to blood pressure. In this review article, we describe common polymorphisms at three steroidogenic loci (CYP11B2, CYP11B1 and CYP17A1) that alter gene transcription efficiency and levels of key steroids, including aldosterone. However, the mechanism by which this occurs remains unclear. While the renin angiotensin system is rightly regarded as the major driver of aldosterone secretion, there is increasing evidence that the contribution of corticotropin (ACTH) is also significant. In light of this, we propose that the differential response of variant CYP11B2, CYP11B1 and CYP17A1 genes to ACTH is an important determinant of blood pressure, tending to predispose individuals with an unfavourable genotype to hypertension

    Absence of Three-Loop Four-Point Divergences in N=4 Supergravity

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    We compute the coefficient of the potential three-loop divergence in pure N=4 supergravity and show that it vanishes, contrary to expectations from symmetry arguments. The recently uncovered duality between color and kinematics is used to greatly streamline the calculation. We comment on all-loop cancellations hinting at further surprises awaiting discovery at higher loops.Comment: 5 pages, 3 figures; v2 added references and minor correction

    The thermodynamic evolution of the cosmological event horizon

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    By manipulating the integral expression for the proper radius ReR_e of the cosmological event horizon (CEH) in a Friedmann-Robertson-Walker (FRW) universe, we obtain an analytical expression for the change \dd R_e in response to a uniform fluctuation \dd\rho in the average cosmic background density ρ\rho. We stipulate that the fluctuation arises within a vanishing interval of proper time, during which the CEH is approximately stationary, and evolves subsequently such that \dd\rho/\rho is constant. The respective variations 2\pi R_e \dd R_e and \dd E_e in the horizon entropy SeS_e and enclosed energy EeE_e should be therefore related through the cosmological Clausius relation. In that manner we find that the temperature TeT_e of the CEH at an arbitrary time in a flat FRW universe is Ee/SeE_e/S_e, which recovers asymptotically the usual static de Sitter temperature. Furthermore, it is proven that during radiation-dominance and in late times the CEH conforms to the fully dynamical First Law T_e \drv S_e = P\drv V_e - \drv E_e, where VeV_e is the enclosed volume and PP is the average cosmic pressure.Comment: 6 page

    MicroRNAs in Aldosterone Production and Action

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    The secretion of aldosterone by the adrenal cortex is a tightly regulated process. Loss of this control can result in severe hypertension and end-organ damage, so detailed understanding of the various mechanisms by which the body regulates aldosterone biosynthesis is key. The emergence of microRNAs (miRNAs) as negative regulators of numerous physiological processes has naturally led to their study in the context of aldosterone production. We summarise several studies that have demonstrated a significant role for microRNAs in aldosterone biosynthesis and action, thereby presenting a possible therapeutic role in the treatment of common forms of hypertension such as primary aldosteronism. Furthermore, the presence of microRNAs in the circulation offers the prospect of accessible and informative biomarkers that may simplify the currently protracted and technically difficult diagnosis of such conditions

    Fast and Slow Rotators in the Densest Environments: a SWIFT IFS study of the Coma Cluster

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    We present integral-field spectroscopy of 27 galaxies in the Coma cluster observed with the Oxford SWIFT spectrograph, exploring the kinematic morphology-density relationship in a cluster environment richer and denser than any in the ATLAS3D survey. Our new data enables comparison of the kinematic morphology relation in three very different clusters (Virgo, Coma and Abell 1689) as well as to the field/group environment. The Coma sample was selected to match the parent luminosity and ellipticity distributions of the early-type population within a radius 15' (0.43 Mpc) of the cluster centre, and is limited to r' = 16 mag (equivalent to M_K = -21.5 mag), sampling one third of that population. From analysis of the lambda-ellipticity diagram, we find 15+-6% of early-type galaxies are slow rotators; this is identical to the fraction found in the field and the average fraction in the Virgo cluster, based on the ATLAS3D data. It is also identical to the average fraction found recently in Abell 1689 by D'Eugenio et al.. Thus it appears that the average slow rotator fraction of early type galaxies remains remarkably constant across many different environments, spanning five orders of magnitude in galaxy number density. However, within each cluster the slow rotators are generally found in regions of higher projected density, possibly as a result of mass segregation by dynamical friction. These results provide firm constraints on the mechanisms that produce early-type galaxies: they must maintain a fixed ratio between the number of fast rotators and slow rotators while also allowing the total early-type fraction to increase in clusters relative to the field. A complete survey of Coma, sampling hundreds rather than tens of galaxies, could probe a more representative volume of Coma and provide significantly stronger constraints, particularly on how the slow rotator fraction varies at larger radii.Comment: Accepted for publication in MNRA

    Optimising outputs from a validated online instrument to measure health-related quality of life (HRQL) in dogs

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    Measurement of health-related quality of life (HRQL) is becoming increasingly valuable within veterinary preventative health care and chronic disease management, as well as in outcomes research. Initial reliability and validation of a 22 item shortened version of VetMetrica (VM), structured questionnaire instrument to measure HRQL in dogs via a mobile application was reported previously. Meaningful interpretation and presentation of the 4 domain scores comprising the HRQL profile generated by VM is key to its successful use in clinical practice and research. Study one describes transformation of domain scores from 0–6 to 0–100 and normalisation of these based on the healthy canine population in two age ranges, such that a score of 50 on a 0–100 scale represents the score for the age-related average healthy dog, and establishment of a threshold to assess domain-specific health status for individual dogs. This provides the clinician with a simple method of ascertaining the health status of an individual dog relative to the average healthy population in the same age group (norm-based scoring). Study two determines the minimum important difference (MID) in domain scores which represents the smallest improvement in score that is meaningful to the dog owner, thus providing the clinician with a means of recognising what is likely to be a significant improvement in scores for an individual dog over time. Visual representation of these guidelines for the purpose of interpreting VM profile scores is presented using case studies
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