1,822 research outputs found

    Transient climate simulations with the HadGEM1 climate model: Causes of past warming and future climate change

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    The ability of climate models to simulate large-scale temperature changes during the twentieth century when they include both anthropogenic and natural forcings and their inability to account for warming over the last 50 yr when they exclude increasing greenhouse gas concentrations has been used as evidence for an anthropogenic influence on global warming. One criticism of the models used in many of these studies is that they exclude some forcings of potential importance, notably from fossil fuel black carbon, biomass smoke, and land use changes. Herein transient simulations with a new model, the Hadley Centre Global Environmental Model version 1 (HadGEM1), are described, which include these forcings in addition to other anthropogenic and natural forcings, and a fully interactive treatment of atmospheric sulfur and its effects on clouds. These new simulations support previous work by showing that there was a significant anthropogenic influence on near-surface temperature change over the last century. They demonstrate that black carbon and land use changes are relatively unimportant for explaining global mean near-surface temperature changes. The pattern of warming in the troposphere and cooling in the stratosphere that has been observed in radiosonde data since 1958 can only be reproduced when the model includes anthropogenic forcings

    Parameters and Predictions for the Long-Period Transiting Planet HD 17156b

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    We report high-cadence time-series photometry of the recently-discovered transiting exoplanet system HD 17156, spanning the time of transit on UT 2007 October 1, from three separate observatories. We present a joint analysis of our photometry, previously published radial velocity measurements, and times of transit center for 3 additional events. Adopting the spectroscopically-determined values and uncertainties for the stellar mass and radius, we estimate a planet radius of Rp = 1.01 +/- 0.09 RJup and an inclination of i = 86.5 +1.1 -0.7 degrees. We find a time of transit center of Tc = 2454374.8338 +/- 0.0020 HJD and an orbital period of P = 21.21691 +/- 0.00071 days, and note that the 4 transits reported to date show no sign of timing variations that would indicate the presence of a third body in the system. Our results do not preclude the existence of a secondary eclipse, but imply there is only a 9.2% chance for this to be present, and an even lower probability (6.9%) that the secondary eclipse would be a non-grazing event. Due to its eccentric orbit and long period, HD 17156b is a fascinating object for the study of the dynamics of exoplanet atmospheres. To aid such future studies, we present theoretical light curves for the variable infrared emission from the visible hemisphere of the planet throughout its orbit.Comment: 8 pages, 4 figures, 1 table, emulateapj format. v2: accepted for publication in ApJ, minor changes. Changed to emulateapj to save the rainforest

    Genetic Variation in Concentration of the 33-mer Protein Subcomponent in Wheat

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    Celiac Disease is a hypersensitive response to gluten caused by HLA-DQ2 or HLA-DQ8 T-cell presentation, initiating destruction of intestinal epithelial cells. Currently, the only remedy for those suffering from celiac disease is elimination of all gluten from the diet. Studies indicate that an indigestible fragment of the gluten molecule, alpha-gliadin subcomponent 33-mer, rich in proline and glutamine, is responsible for the hypersensitivity response. Determination of 33-mer concentration in wheat lines could be beneficial to future development of wheat lines with reduced 33-mer concentration. Protein from wheat flour was extracted and subjected to ELISA techniques in order to quantify the concentration of 33-mer. A technique that quantifies the concentration of 33-mer is a necessary first step for future research efforts focused on identification and development of wheat lines with reduced concentrations of 33-mer. It is possible that wheat with reduced 33-mer may be suitable for consumption by individuals with celiac disease

    Radio continuum observations of Class I protostellar disks in Taurus: constraining the greybody tail at centimetre wavelengths

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    We present deep 1.8 cm (16 GHz) radio continuum imaging of seven young stellar objects in the Taurus molecular cloud. These objects have previously been extensively studied in the sub-mm to NIR range and their SEDs modelled to provide reliable physical and geometrical parametres.We use this new data to constrain the properties of the long-wavelength tail of the greybody spectrum, which is expected to be dominated by emission from large dust grains in the protostellar disk. We find spectra consistent with the opacity indices expected for such a population, with an average opacity index of beta = 0.26+/-0.22 indicating grain growth within the disks. We use spectra fitted jointly to radio and sub-mm data to separate the contributions from thermal dust and radio emission at 1.8 cm and derive disk masses directly from the cm-wave dust contribution. We find that disk masses derived from these flux densities under assumptions consistent with the literature are systematically higher than those calculated from sub-mm data, and meet the criteria for giant planet formation in a number of cases.Comment: submitted MNRA

    Comprehensive Evidence-Based Assessment and Prioritization of Potential Antidiabetic Medicinal Plants: A Case Study from Canadian Eastern James Bay Cree Traditional Medicine

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    Canadian Aboriginals, like others globally, suffer from disproportionately high rates of diabetes. A comprehensive evidence-based approach was therefore developed to study potential antidiabetic medicinal plants stemming from Canadian Aboriginal Traditional Medicine to provide culturally adapted complementary and alternative treatment options. Key elements of pathophysiology of diabetes and of related contemporary drug therapy are presented to highlight relevant cellular and molecular targets for medicinal plants. Potential antidiabetic plants were identified using a novel ethnobotanical method based on a set of diabetes symptoms. The most promising species were screened for primary (glucose-lowering) and secondary (toxicity, drug interactions, complications) antidiabetic activity by using a comprehensive platform of in vitro cell-based and cell-free bioassays. The most active species were studied further for their mechanism of action and their active principles identified though bioassay-guided fractionation. Biological activity of key species was confirmed in animal models of diabetes. These in vitro and in vivo findings are the basis for evidence-based prioritization of antidiabetic plants. In parallel, plants were also prioritized by Cree Elders and healers according to their Traditional Medicine paradigm. This case study highlights the convergence of modern science and Traditional Medicine while providing a model that can be adapted to other Aboriginal realities worldwide

    AMI-LA radio continuum observations of Spitzer c2d small clouds and cores: Serpens region

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    We present deep radio continuum observations of the cores identified as deeply embedded young stellar objects in the Serpens molecular cloud by the Spitzer c2d programme at a wavelength of 1.8cm with the Arcminute Microkelvin Imager Large Array (AMI-LA). These observations have a resolution of ~30arcsec and an average sensitivity of 19microJy/beam. The targets are predominantly Class I sources, and we find the detection rate for Class I objects in this sample to be low (18%) compared to that of Class 0 objects (67%), consistent with previous works. For detected objects we examine correlations of radio luminosity with bolometric luminosity and envelope mass and find that these data support correlations found by previous samples, but do not show any indiction of the evolutionary divide hinted at by similar data from the Perseus molecular cloud when comparing radio luminosity with envelope mass. We conclude that envelope mass provides a better indicator for radio luminosity than bolometric luminosity, based on the distribution of deviations from the two correlations. Combining these new data with archival 3.6cm flux densities we also examine the spectral indices of these objects and find an average spectral index of 0.53+/-1.14, consistent with the canonical value for a partially optically thick spherical or collimated stellar wind. However, we caution that possible inter-epoch variability limits the usefulness of this value, and such variability is supported by our identification of a possible flare in the radio history of Serpens SMM 1.Comment: accepted MNRA

    Visitor expenditure estimation for grocery store location planning: a case study of Cornwall

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    Visitor expenditure is an important driver of demand in many local economies, supporting a range of services and facilities which may not be viable based solely on residential demand. In areas where self-catering accommodation is prevalent visitor demand makes up a considerable proportion of sales and revenue within grocery stores, yet this form of visitor consumption is commonly overlooked in supply and demand-side estimates of visitor spend. As such, store location planning in tourist resorts, decisions about local service provision and the local economic impacts of tourism are based on very limited demand-side estimates of visitor spend. Using Cornwall, South West England as a study area, we outline a methodology and data sources to estimate small-area visitor grocery spend. We use self-catering accommodation provision, utilisation and visitor expenditure rates as key factors driving visitor spend. We identify that the use of visitor accommodation accounts for the spatial and temporal complexities of visitor demand that may be overlooked when using alternative approaches, such as the up-scaling of residential demand. Using a spatial interaction model, we demonstrate that our expenditure estimates can be used to generate store level revenue estimation within tourist resorts, and we make a number of recommendations for service provision and store location planning in these areas
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