773 research outputs found

    The effect of hydrostatic pressure environment on the low cycle fatigue properties of a maraging steel

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    Tests were conducted in a specially constructed fatigue machine which allowed the maintenance of a steady triaxial hydrostatic pressure on the specimen and simultaneous application of push-pull uniaxial tensional and compressive stresses

    Proxy SVARs : asymptotic theory, bootstrap inference, and the effects of income tax changes in the United States

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    Proxy structural vector autoregressions (SVARs)identify structural shocks in vector autoregressions (VARs) with external proxy variables that are correlated with the structural shocks of interest but uncorrelated with other structural shocks. We provide asymptotic theory for proxy SVARs when the VAR innovations and proxy variables are jointly a-mixing. We also prove the asymptotic validity of a residual-based moving block bootstrap (MBB) for inference on statistics that depend jointly on estimators for the VAR coeffcients and for covariances of the VAR innovations and proxy variables. These statistics include structural impulse response functions (IRFs). Conversely, wild bootstraps are invalid, even when innovations and proxy variables are either independent and identically distributed or martingale difference sequences, and simulations show that their coverage rates for IRFs can be badly mis-sized. Using the MBB to re-estimate confidence intervals for the IRFs in Mertens and Ravn (2013), we show that inferences cannot be made about the effects of tax changes on output, labor, or investment

    Local cultures in institutional contexts: The functions of academic departments in liberal arts colleges

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    The academic department remains understudied as a context of faculty work, particularly in institutional settings beyond the research university. In this article, we report findings from a study of faculty experiences within academic departments in liberal arts colleges, through analysis of interviews with 55 faculty members representing a 13-member consortium of liberal arts institutions in the mid-western U.S. Through inductive analysis and deductive coding from existing models, we identified five functions of departments in liberal arts colleges, including: (a) faculty hiring, retention, and promotion; (b) new faculty socialization; (c) informal interactions, mentoring, and network-building; (d) establishing and communicating institutional and departmental policies, practices, and procedures; and (e) the structuring of academic work. Findings suggest that departmental functions in liberal arts colleges are generally the same as those in other institution types, but play out differently and thus have different consequences for academic careers. Across functions, liberal arts colleges seem to be undergoing an evolution, or perhaps revolution, that has implications for academic work in such contexts

    Systems Alignment for Comprehensive Faculty Development in Liberal Arts Colleges

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    Using an alignment framework, the authors explore faculty development initiatives in liberal arts colleges in order to understand the connection between organizational priorities and processes as connected to faculty members’ stated needs. The study draws on mixed methods data from The Initiative for Faculty Development in Liberal Arts Colleges (IFDLAC), including survey andinterview data from the 13 member institutions of the Great Lakes Colleges Association (GLCA).The authors offer future implications for faculty development practice

    Instructional Resources to Assess Applied Projects as a Culminating Graduate Communication Student Experience

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    This study reviews the traditional culminating graduate student experiences, theses, and comprehensive exams, as well as a newer, more professionally relevant option, applied research projects. We conceptualize applied projects as student-led, client-connected, hands-on, experiential projects that address a real-world communication problem or topic through the creation of relevant deliverables. We used Glassick et al.’s (1997) scholarship assessed model and the National Communication Association’s communication learning outcomes to determine perceived differences between culminating experiences. Survey results (N = 32) of recent alumni and current master’s level Communication students demonstrate near-equal ratings of applied projects and theses in their ability to both meet scholarship assessment criteria and communication learning outcomes. Comprehensive exams are rated comparatively worse. Based on these criteria and others gained from implementing applied projects as an option for students, we offer a rubric for assessing master’s level applied research projects

    Do slower life history strategies reduce sociodemographic sex differences?

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    This study examines the relations between sociodemographic sex differences and life history strategies in the populations of Mexican States. Sex differences in anatomy and behavior was measured with traits such as educational achievement, mortality, and morbidity. The data were obtained from the Instituto Nacional de Estadística y Geografía (INEGI) and sampled from thirty-one Mexican states and the Federal District (N = 32). An extension analysis was performed selecting only the sex ratio variables that had a correlation with the slow Life History factor greater than or equal to an absolute value of .25. A unit-weighted sex ratio factor was created using these variables. Across 32 Mexican states, the correlation between latent slow life history and sex ratio was .57 (p .05). These results are consistent with our hypothesis that slower life histories favor reduced sexual dimorphism in physiology and behavior among human subnational populations. The results of the study further understanding of variations in population sex differences, male-biased behaviors toward sexual equality, and the differences among subnational (regional) populations within the United States of Mexico.   DOI:10.2458/azu_jmmss_v6i1_chavarria_miner

    The OSIRIS-REx Visible and InfraRed Spectrometer (OVIRS): Spectral Maps of the Asteroid Bennu

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    The OSIRIS-REx Visible and Infrared Spectrometer (OVIRS) is a point spectrometer covering the spectral range of 0.4 to 4.3 microns (25,000-2300 cm-1). Its primary purpose is to map the surface composition of the asteroid Bennu, the target asteroid of the OSIRIS-REx asteroid sample return mission. The information it returns will help guide the selection of the sample site. It will also provide global context for the sample and high spatial resolution spectra that can be related to spatially unresolved terrestrial observations of asteroids. It is a compact, low-mass (17.8 kg), power efficient (8.8 W average), and robust instrument with the sensitivity needed to detect a 5% spectral absorption feature on a very dark surface (3% reflectance) in the inner solar system (0.89-1.35 AU). It, in combination with the other instruments on the OSIRIS-REx Mission, will provide an unprecedented view of an asteroid's surface.Comment: 14 figures, 3 tables, Space Science Reviews, submitte

    The Green Bank Northern Celestial Cap Pulsar Survey - I: Survey Description, Data Analysis, and Initial Results

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    We describe an ongoing search for pulsars and dispersed pulses of radio emission, such as those from rotating radio transients (RRATs) and fast radio bursts (FRBs), at 350 MHz using the Green Bank Telescope. With the Green Bank Ultimate Pulsar Processing Instrument, we record 100 MHz of bandwidth divided into 4,096 channels every 81.92 μs\mu s. This survey will cover the entire sky visible to the Green Bank Telescope (δ>−40∘\delta > -40^\circ, or 82% of the sky) and outside of the Galactic Plane will be sensitive enough to detect slow pulsars and low dispersion measure (<<30 pc cm−3\mathrm{pc\,cm^{-3}}) millisecond pulsars (MSPs) with a 0.08 duty cycle down to 1.1 mJy. For pulsars with a spectral index of −-1.6, we will be 2.5 times more sensitive than previous and ongoing surveys over much of our survey region. Here we describe the survey, the data analysis pipeline, initial discovery parameters for 62 pulsars, and timing solutions for 5 new pulsars. PSR J0214++5222 is an MSP in a long-period (512 days) orbit and has an optical counterpart identified in archival data. PSR J0636++5129 is an MSP in a very short-period (96 minutes) orbit with a very low mass companion (8 MJM_\mathrm{J}). PSR J0645++5158 is an isolated MSP with a timing residual RMS of 500 ns and has been added to pulsar timing array experiments. PSR J1434++7257 is an isolated, intermediate-period pulsar that has been partially recycled. PSR J1816++4510 is an eclipsing MSP in a short-period orbit (8.7 hours) and may have recently completed its spin-up phase.Comment: 18 pages, 10 figures, 5 tables, accepted by Ap
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