3,734 research outputs found

    The Effect of Changing Government Subsidy Programs: An Analysis of Revenue at the Farm level

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    Producer revenue is simultaneously simulated for several hundred county-specific representative farms. The effects of current and alternative commodity programs are analyzed. In particular, two variations of revenue-triggered programs similar to plans proposed by the National Corn Growers Association are evaluated.Risk, commodity policy, simulation, Agricultural and Food Policy, Risk and Uncertainty, Q180,

    The Dwarfs Beyond: The Stellar-to-Halo Mass Relation for a New Sample of Intermediate Redshift Low Mass Galaxies

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    A number of recent challenges to the standard Lambda-CDM paradigm relate to discrepancies that arise in comparing the abundance and kinematics of local dwarf galaxies with the predictions of numerical simulations. Such arguments rely heavily on the assumption that the local dwarf and satellite galaxies form a representative distribution in terms of their stellar-to-halo mass ratios. To address this question, we present new, deep spectroscopy using DEIMOS on Keck for 82 low mass (10^7-10^9 solar masses) star-forming galaxies at intermediate redshift (z=0.2-1). For 50 percent of these we are able to determine resolved rotation curves using nebular emission lines and thereby construct the stellar mass Tully-Fisher relation to masses as low as 10^7 solar masses. Using scaling relations determined from weak lensing data, we convert this to a stellar-to-halo mass (SHM) relation for comparison with abundance matching predictions. We find a discrepancy between the propagated predictions from simulations compared to our observations, and suggest possible reasons for this as well as future tests that will be more effective.Comment: 11 pages, 7 figures, submitted to ApJ, comments welcom

    History, myth, and audience in Thucydides: Harmodius and Aristogeiton

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    Thucydides’ critique of history’s reception in the proem of book 1 is meant to have a rhetorical effect upon his own history’s recipients: he aims his proem at a sophisticated and self-interested audience that wants to demonstrate its interest in accurate knowledge, as opposed to flattering τὸ μυθῶδες. Thucydides subsequently employs speeches to dramatize the Athenians’ relationship to historical and political knowledge, showing how confusions engendered by the political rhetoric of Pericles’ funeral oration climax in the principled selfignorance displayed in the Herms and Mysteries trials of 415. Through this dramatization of the problems with the Athenians’ relationship to knowledge, especially in his double treatment of the politically charged Harmodius and Aristogeiton story, Thucydides moves his readers away from the assumptions that he attributes to them at the start of his composition, and educates them in the significance of the absence of τὸ μυθῶδες from his histories

    Kpc-scale Properties of Emission-line Galaxies

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    We perform a detailed study of the resolved properties of emission-line galaxies at kpc-scale to investigate how small-scale and global properties of galaxies are related. 119 galaxies with high-resolution Keck/DEIMOS spectra are selected to cover a wide range in morphologies over the redshift range 0.2<z<1.3. Using the HST/ACS and HST/WFC3 imaging data taken as a part of the CANDELS project, for each galaxy we perform SED fitting per resolution element, producing resolved rest-frame U-V color, stellar mass, star formation rate, age and extinction maps. We develop a technique to identify blue and red "regions" within individual galaxies, using their rest-frame color maps. As expected, for any given galaxy, the red regions are found to have higher stellar mass surface densities and older ages compared to the blue regions. Furthermore, we quantify the spatial distribution of red and blue regions with respect to both redshift and stellar mass, finding that the stronger concentration of red regions toward the centers of galaxies is not a significant function of either redshift or stellar mass. We find that the "main sequence" of star forming galaxies exists among both red and blue regions inside galaxies, with the median of blue regions forming a tighter relation with a slope of 1.1+/-0.1 and a scatter of ~0.2 dex compared to red regions with a slope of 1.3+/-0.1 and a scatter of ~0.6 dex. The blue regions show higher specific Star Formation Rates (sSFR) than their red counterparts with the sSFR decreasing since z~1, driver primarily by the stellar mass surface densities rather than the SFRs at a giver resolution element.Comment: 17 pages, 17 figures, Submitted to the Ap

    Homozygous in-frame deletion in CATSPERE in a man producing spermatozoa with loss of CatSper function and compromised fertilizing capacity

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    STUDY QUESTIONDoes a man (patient 1) with a previously described deficiency in principle cation channel of sperm (CatSper) function have a mutation in the CatSper-epsilon (CATSPERE) and/or CatSper-zeta (CATSPERZ) gene?SUMMARY ANSWERPatient 1 has a homozygous in-frame 6-bp deletion in exon 18 (c.2393_2398delCTATGG, rs761237686) of CATSPERE.WHAT IS KNOWN ALREADYCatSper is the principal calcium channel of mammalian spermatozoa. Spermatozoa from patient 1 had a specific loss of CatSper function and were unable to fertilize at IVF. Loss of CatSper function could not be attributed to genetic abnormalities in coding regions of seven CatSper subunits. Two additional subunits (CatSper-epsilon (CATPSERE) and CatSper-zeta (CATSPERZ)) were recently identified, and are now proposed to contribute to the formation of the mature channel complex.STUDY DESIGN, SIZE, DURATIONThis was a basic medical research study analysing genomic data from a single patient (patient 1) for defects in CATSPERE and CATSPERZ.PARTICIPANTS/MATERIALS, SETTING, METHODSThe original exome sequencing data for patient 1 were analysed for mutations in CATSPERE and CATSPERZ. Sanger sequencing was conducted to confirm the presence of a rare variant.MAIN RESULTS AND THE ROLE OF CHANCEPatient 1 is homozygous for an in-frame 6-bp deletion in exon 18 (c.2393_2398delCTATGG, rs761237686) of CATSPERE that is predicted to be highly deleterious.LIMITATIONS, REASONS FOR CAUTIONThe nature of the molecular deficit caused by the rs761237686 variant and whether it is exclusively responsible for the loss of CatSper function remain to be elucidated.WIDER IMPLICATIONS OF THE FINDINGSPopulation genetics are available for a significant number of predicted deleterious variants of CatSper subunits. The consequence of homozygous and compound heterozygous forms on sperm fertilization potential could be significant. Selective targeting of CatSper subunit expression maybe a feasible strategy for the development of novel contraceptives.STUDY FUNDING/COMPETING INTEREST(S)This study was funded by project grants from the MRC (MR/K013343/1 and MR/012492/1), Chief Scientist Office/NHS research Scotland. This work was also supported by NIH R01GM111802, Pew Biomedical Scholars Award 00028642 and Packer Wentz Endowment Will to P.V.L. C.L.R.B is the editor-in-chief of Molecular Human Reproduction, has received lecturing fees from Merck and Ferring, and is on the Scientific Advisory Panel for Ohana BioSciences. C.L.R.B was chair of the World Health Organization Expert Synthesis Group on Diagnosis of Male infertility (2012–2016)

    Creep in Photovoltaic Modules: Examining the Stability of Polymeric Materials and Components

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    Interest in renewable energy has motivated the implementation of new polymeric materials in photovoltaic modules. Some of these are non-cross-linked thermoplastics, in which there is a potential for new behaviors to occur, including phase transformation and visco-elastic flow. Differential scanning calorimetry and rheometry data were obtained and then combined with existing site-specific time-temperature information in a theoretical analysis to estimate the displacement expected to occur during module service life. The analysis identified that, depending on the installation location, module configuration and/or mounting configuration, some of the thermoplastics are expected to undergo unacceptable physical displacement. While the examples here focus on encapsulation materials, the concerns apply equally to the frame, junction-box, and mounting-adhesive technologies

    Critical Realignment of Humboldt’s “Normal School”: Meeting the Changing Landscape of Teacher Education

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    Our team of teacher educators share our process for reconceptualizing and reaffirming our vision of teacher education as the larger university shifts focus to that of becoming a polytechnic institution. We developed a heuristic to help us articulate our vision based on our commitments and contexts, and discuss the practical implications that this work has in our coursework and clinical practice. Our vision of the polytechnic teacher centers around four commitments: reflective, relational, reconstructive and research-oriented teaching. These commitments are informed by and exist in relationship with broader concepts of positionality, communities of practice, community partners, and polytechnic perspectives

    The Assembly History of Disk Galaxies: II. Probing the Emerging Tully-Fisher Relation During 1<z<1.7

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    Through extended integrations using the recently-installed deep depletion CCD on the red arm of the Keck I Low Resolution Imaging Spectrograph, we present new measurements of the resolved spectra of 70 morphologically-selected star-forming galaxies with i_AB<24.1 in the redshift range 1<z<1.7. Using the formalism introduced in Paper I of this series and available HST ACS images, we successfully recover rotation curves using the extended emission line distribution of [O II] 3727 A to 2.2 times the disk scale radius for a sample of 42 galaxies. Combining these measures with stellar masses derived from HST and ground-based near-infrared photometry enables us to construct the stellar mass Tully-Fisher relation in the time interval between the well-constructed relation defined at z~1 in Paper I and the growing body of resolved dynamics probed with integral field unit spectrographs at z>2. Remarkably, we find a well-defined Tully-Fisher relation with up to 60% increase in scatter and stellar mass zero-point shift constraint of 0.02+/-0.02 dex since z~1.7, compared to the local relation. Although our sample is incomplete in terms of either a fixed stellar mass or star formation rate limit, we discuss the implications that typical star-forming disk galaxies evolve to arrive on a well-defined Tully-Fisher relation within a surprisingly short period of cosmic history.Comment: 13 pages, 8 figures, accepted for publication at Ap
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