5,626 research outputs found

    Motivations to Control Prejudice Bias Performance Feedback in Developmental Relationships

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    In developmental relationships, providing accurate assessments of performance is necessary to maximize the developmental benefits for those receiving the feedback. Research suggests that performance assessments for underrepresented minorities are susceptible to biases related to out-group prejudice; however, little is known about the contributions of motivations to control prejudice, particularly in face-to-face settings. Addressing this, we examined the influences of internal and external motivations to control prejudice (IMS and EMS) on the positivity of White mentor’s feedback about their underrepresented minority mentee’s task performance. We analyzed video-recorded interactions between 56 randomly assigned cross-racial dyads, wherein mentees performed a speech task and were given subsequent face-to-face verbal feedback from their mentor. To gain comparatively unbiased assessments of feedback positivity and of mentee performance, we used independent coders. Using structural equation modeling, our results suggested that positivity of mentors’ feedback was uniquely predicted by both IMS and EMS over and above mentee performance

    Management Systems in Secondary Reading Classrooms

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    One outcome of federal, state or district funding of reading programs has been the development of a competency based curriculum with the inclusion of a classroom management system. This management system is the structure for the implementation of the goals, guidelines and behavioral objectives of the program. Each program with its management system is developed and written by teachers In consultation with school and/or district level cooperation

    The role of cosmic ray pressure in accelerating galactic outflows

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    We study the formation of galactic outflows from supernova explosions (SNe) with the moving-mesh code AREPO in a stratified column of gas with a surface density similar to the Milky Way disk at the solar circle. We compare different simulation models for SNe placement and energy feedback, including cosmic rays (CR), and find that models that place SNe in dense gas and account for CR diffusion are able to drive outflows with similar mass loading as obtained from a random placement of SNe with no CRs. Despite this similarity, CR-driven outflows differ in several other key properties including their overall clumpiness and velocity. Moreover, the forces driving these outflows originate in different sources of pressure, with the CR diffusion model relying on non-thermal pressure gradients to create an outflow driven by internal pressure and the random-placement model depending on kinetic pressure gradients to propel a ballistic outflow. CRs therefore appear to be non-negligible physics in the formation of outflows from the interstellar medium.Comment: 8 pages, 4 figures, accepted for publication in ApJL; movie of simulated gas densities can be found here: http://www.h-its.org/tap-images/galactic-outflows

    Novel splice variants associated with one of the zebrafish dnmt3 genes

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    BACKGROUND: DNA methylation and the methyltransferases are known to be important in vertebrate development and this may be particularly true for the Dnmt3 family of enzymes because they are thought to be the de novo methyltransferases. Mammals have three Dnmt3 genes; Dnmt3a, Dnmt3b, and Dnmt3L, two of which encode active enzymes and one of which produces an inactive but necessary cofactor. However, due to multiple promoter use and alternative splicing there are actually a number of dnmt3 isoforms present. Six different dnmt3 genes have recently been identified in zebrafish. RESULTS: We have examined two of the dnmt3 genes in zebrafish that are located in close proximity in the same linkage group and we find that the two genes are more similar to each other than they are to the other zebrafish dnmt3 genes. We have found evidence for the existence of several different splice variants and alternative splice sites associated with one of the two genes and have examined the relative expression of these genes/variants in a number of zebrafish developmental stages and tissues. CONCLUSION: The similarity of the dnmt3-1 and dnmt3-2 genes suggests that they arose due to a relatively recent gene duplication event. The presence of alternative splice and start sites, reminiscent of what is seen with the human DNMT3s, demonstrates strong parallels between the control/function of these genes across vertebrate species. The dynamic expression levels of these genes/variants suggest that they may well play a role in early development and this is particularly true for dnmt3-2-1 and dnmt3-1. dnmt3-2-1 is the predominantly expressed form prior to zygotic gene activation whereas dnmt3-1 predominates post zygotic gene activation suggesting a distinct developmental role for each

    How Cosmic Rays Mediate the Evolution of the Interstellar Medium

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    We explore the impact of diffusive cosmic rays (CRs) on the evolution of the interstellar medium (ISM) under varying assumptions of supernova explosion environment. In practice, we systematically vary the relative fractions of supernovae (SN) occurring in star-forming high-density gas and those occurring in random locations decoupled from star-forming gas to account for SN from run-away stars or explosions in regions that have been cleared by prior SN, stellar winds, or radiation. We explore various mixed models by adjusting these fractions relative to each other. We find that in the simple system of a periodic stratified gas layer the ISM structure will evolve to one of two solutions: a "peak driving" state where warm gas is volume filling or a "thermal runaway" state where hot gas is volume filling. CR pressure and transport are important factors that strongly influence the solution state the ISM reaches and have the ability to flip the ISM between solutions. Observable signatures such as gamma ray emission and HI gas are explored. We find that gamma ray luminosity from pion decay is largely consistent with observations for a range of model parameters. The thickness of the HI gas layer may be too compact, however, this may be due to a large cold neutral fraction of midplane gas. The volume fraction of hot gas evolves to stable states in both solutions, but neither settles to a Milky Way-like configuration, suggesting that additional physics which is omitted here (e.g. a cosmological circum-galactic medium, radiation transport, or spectrally resolved and spatially varying CR transport) may be required.Comment: 27 pages, 21 Figures, submitted to MNRAS, comments welcom

    How cosmic rays mediate the evolution of the interstellar medium

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    Funding: CP acknowledges support by the European Research Council under ERC-CoG grant CRAGSMAN-646955.We explore the impact of diffusive cosmic rays (CRs) on the evolution of the interstellar medium (ISM) under varying assumptions of supernova explosion environment. In practice, we systematically vary the relative fractions of supernovae (SN) occurring in star-forming high-density gas and those occurring in random locations decoupled from star-forming gas to account for SN from run-away stars or explosions in regions that have been cleared by prior SN, stellar winds, or radiation. We find that in the simple system of a periodic stratified gas layer the ISM structure will evolve to one of two solutions: a ‘peak driving’ state where warm gas is volume filling or a ‘thermal runaway’ state where hot gas is volume filling. CR pressure and transport are important factors that strongly influence the solution state the ISM reaches and have the ability to flip the ISM between solutions. Observable signatures such as gamma-ray emission and H I gas are explored. We find that gamma-ray luminosity from pion decay is largely consistent with observations for a range of model parameters. The thickness of the H I gas layer may be too compact, however, this may be due to a large cold neutral fraction of mid-plane gas. The volume fraction of hot gas evolves to stable states in both solutions, but neither settles to a Milky Way-like configuration, suggesting that additional physics omitted here (e.g. a cosmological circumgalactic medium, radiation transport, or spectrally resolved and spatially varying CR transport) may be required.Peer reviewe

    Exploring Terrestrial Planet Formation in the TW Hydrae Association

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    Spitzer Space Telescope infrared measurements are presented for 24 members of the TW Hydrae association (TWA). High signal-to-noise 24-micron (um) photometry is presented for all of these stars, including 20 stars that were not detected by IRAS. Among these 20 stars, only a single object, TWA 7, shows excess emission at 24um and at the level of only 40% above the star's photosphere. TWA 7 also exhibits a strong 70um excess that is a factor of 40 brighter than the stellar photosphere at this wavelength. At 70um, an excess of similar magnitude is detected for TWA 13, though no 24um excess was detected for this binary. For the 18 stars that failed to show measurable IR excesses, the sensitivity of the current 70um observations does not rule out substantial cool excesses at levels 10-40x above their stellar continua. Measurements of two T Tauri stars, TW Hya and Hen 6-300, confirm that their spectacular IR spectral energy distributions (SEDs) do not turn over even by 160um, consistent with the expectation for their active accretion disks. In contrast, the Spitzer data for the luminous planetary debris systems in the TWA, HD 98800B and HR 4796A, are consistent with single-temperature blackbody SEDs. The major new result of this study is the dramatic bimodal distribution found for the association in the form of excess emission at a wavelength of 24um, indicating negligible amounts of warm (>100 K) dust and debris around 20 of 24 stars in this group of very young stars. This bimodal distribution is especially striking given that the four stars in the association with strong IR excesses are >100x brighter at 24um than their photospheres

    Temporal inflection points in decorated pottery: a bayesian refinement of the late formative chronology in the Southern Lake Titicaca Basin, Bolivia

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    The Late Formative period immediately precedes the emergence of Tiwanaku, one of the earliest South American states, yet it is one of the most poorly understood periods in the southern Lake Titicaca Basin (Bolivia). In this article, we refine the ceramic chronology of this period with large sets of dates from eight sites, focusing on temporal inflection points in decorated ceramic styles. These points, estimated here by Bayesian models, index specific moments of change: (1) cal AD 120 (60-170, 95% probability): the first deposition of Kalasasaya red-rimmed and zonally incised styles; (2) cal AD 240 (190-340, 95% probability): a tentative estimate of the final deposition of Kalasasaya zonally incised vessels; (3) cal AD 420 (380-470, 95% probability): the final deposition of Kalasasaya red-rimmed vessels; and (4) cal AD 590 (500-660, 95% probability): the first deposition of Tiwanaku Redwares. These four modeled boundaries anchor an updated Late Formative chronology, which includes the Initial Late Formative phase, a newly identified decorative hiatus between the Middle and Late Formative periods. The models place Qeya and transitional vessels between inflection points 3 and 4 based on regionally consistent stratigraphic sequences. This more precise chronology will enable researchers to explore the trajectories of other contemporary shifts during this crucial period in Lake Titicaca Basin's prehistory.Fil: Marsh, Erik Johnson. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentina. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales. Laboratorio de Paleoecología Humana; ArgentinaFil: Roddick, Andrew P.. Mc Master University; CanadáFil: Bruno, Maria C.. Dickinson College; Estados UnidosFil: Smith, Scott C.. Franklin & Marshall College; Estados UnidosFil: Janusek, John W.. Vanderbilt University; Estados UnidosFil: Hastorf, Christine A.. University of California at Berkeley; Estados Unido
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