467 research outputs found

    Mass-Richness relations for X-ray and SZE-selected clusters at 0.4<z<2.00.4 < z <2.0 as seen by SpitzerSpitzer at 4.5ÎĽ\mum

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    We study the mass-richness relation of 116 spectroscopically-confirmed massive clusters at 0.4<z<20.4 < z < 2 by mining the SpitzerSpitzer archive. We homogeneously measure the richness at 4.5μ\mum for our cluster sample within a fixed aperture of 2′2^{\prime} radius and above a fixed brightness threshold, making appropriate corrections for both background galaxies and foreground stars. We have two subsamples, those which have a) literature X-ray luminosities and b) literature Sunyaev-Zeldovich effect masses. For the X-ray subsample we re-derive masses adopting the most recent calibrations. We then calibrate an empirical mass-richness relation for the combined sample spanning more than one decade in cluster mass and find the associated uncertainties in mass at fixed richness to be ±0.25\pm 0.25 dex. We study the dependance of the scatter of this relation with galaxy concentration, defined as the ratio between richness measured within an aperture radius of 1 and 2 arcminutes. We find that at fixed aperture radius the scatter increases for clusters with higher concentrations. We study the dependance of our richness estimates with depth of the [4.5]μ\mum imaging data and find that reaching a depth of at least [4.5]= 21 AB mag is sufficient to derive reasonable mass estimates. We discuss the possible extension of our method to the mid-infrared WISEWISE all-sky survey data, and the application of our results to the EuclidEuclid mission. This technique makes richness-based cluster mass estimates available for large samples of clusters at very low observational cost.Comment: Submitted to ApJ on Aug 31 2016, Revised version resubmitted on Apr 11th 201

    Planning for the Sun to Come Up: How Nevada and California Explain the Future of Net Metering

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    This Article explores the growth of rooftop solar and the future of net metering through the debates and policies of Nevada and California. Part II details the recent, rapid growth and projected future growth of solar power in the United States. Part II also describes how Nevada and Californiaare leading the nation in utilization of solar power and are already addressing issues that are likely to emerge in other areas of the country. Part III begins with a brief introduction to net metering and the national scope of net metering program reviews. Part III concludes with a summary of the most recent changes to each states net metering laws. Part IV contains a comparative analysis of five key legislative and regulatory factors influencing how net metering will develop in the future. The elements are the interaction between renewable portfolio standards and net metering programs, solar photovoltaic (PV) incentive programs, time-of-use rates, electricity sector decoupling, and comprehensive electric grid planning. Part V summarizes key findings from our research and provides lessons learned for other states considering evolving their net metering programs. Part VI concludes this article with a forward-looking assessment of the challenges facing net metering

    Structural and functional characterization of the two phosphoinositide binding sites of PROPPINs.

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    β-propellers that bind polyphosphoinositides (PROPPINs), a eukaryotic WD-40 motif-containing protein family, bind via their predicted β-propeller fold the polyphosphoinositides PtdIns3P and PtdIns(3,5)P2 using a conserved FRRG motif. PROPPINs play a key role in macroautophagy in addition to other functions. We present the 3.0-Å crystal structure of Kluyveromyces lactis Hsv2, which shares significant sequence homologies with its three Saccharomyces cerevisiae homologs Atg18, Atg21, and Hsv2. It adopts a seven-bladed β-propeller fold with a rare nonvelcro propeller closure. Remarkably, in the crystal structure, the two arginines of the FRRG motif are part of two distinct basic pockets formed by a set of highly conserved residues. In comprehensive in vivo and in vitro studies of ScAtg18 and ScHsv2, we define within the two pockets a set of conserved residues essential for normal membrane association, phosphoinositide binding, and biological activities. Our experiments show that PROPPINs contain two individual phosphoinositide binding sites. Based on docking studies, we propose a model for phosphoinositide binding of PROPPINs

    Caregiver Criticism, Help-giving and the Burden of Schizophrenia Among Mexican American Families

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    Objectives—The present study tested an attribution model of help-giving in family caregivers of persons with schizophrenia as it relates to caregivers’ reported burden. We hypothesized (a) that caregivers’ attributions of their ill relatives’ responsibility for their symptoms would be associated with more negative and less positive affective reactions, (b) that affective reactions would be related to perceptions of administered support, and (c) that support would in turn predict greater burden. Methods—We examined 60 family caregivers of Mexican origin living in Southern California. Mexican Americans were chosen because of their high degree of contact with their ill relative thereby facilitating the examination of help-giving and burden. Contrary to past studies, caregivers’ attributions and affective stance were assessed independently, the former based on self-report and the latter based on codes drawn from the Camberwell Family Interview. Caregiver burden was assessed at baseline and one year later. Results—Path analyses showed partial support for the attribution model of help-giving. Specifically, attributions of responsibility negatively predicted caregiver’s warmth, which in turn predicted more administered support. Contrary to hypotheses, attributions were not associated with caregiver criticism, and criticism was positively related to administered support. In addition, caregiver support was not related to burden at either baseline or a year later. Criticism was a significant predictor of burden at follow-up through burden at baseline. Conclusion—The emotional stance of caregivers predicts burden independent of the help they provide. Caregiver criticism not only predicts negative patient outcomes but can predict negative caregiver outcomes as well

    Calibration and data quality of warm IRAC

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    We present an overview of the calibration and properties of data from the IRAC instrument aboard the Spitzer Space Telescope taken after the depletion of cryogen. The cryogen depleted on 15 May 2009, and shortly afterward a two-month- long calibration and characterization campaign was conducted. The array temperature and bias setpoints were revised on 19 September 2009 to take advantage of lower than expected power dissipation by the instrument and to improve sensitivity. The final operating temperature of the arrays is 28.7 K, the applied bias across each detector is 500 mV and the equilibrium temperature of the instrument chamber is 27.55 K. The final sensitivities are essentially the same as the cryogenic mission with the 3.6 ÎĽm array being slightly less sensitive (10%) and the 4.5 ÎĽm array within 5% of the cryogenic sensitivity. The current absolute photometric uncertainties are 4% at 3.6 and 4.5 ÎĽm, and better than milli-mag photometry is achievable for long-stare photometric observations. With continued analysis, we expect the absolute calibration to improve to the cryogenic value of 3%. Warm IRAC operations fully support all science that was conducted in the cryogenic mission and all currently planned warm science projects (including Exploration Science programs). We expect that IRAC will continue to make ground-breaking discoveries in star formation, the nature of the early universe, and in our understanding of the properties of exoplanets
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