8,680 research outputs found

    Comparisons of elastic and rigid blade-element rotor models using parallel processing technology for piloted simulations

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    A piloted comparison of rigid and aeroelastic blade-element rotor models was conducted at the Crew Station Research and Development Facility (CSRDF) at Ames Research Center. A simulation development and analysis tool, FLIGHTLAB, was used to implement these models in real time using parallel processing technology. Pilot comments and quantitative analysis performed both on-line and off-line confirmed that elastic degrees of freedom significantly affect perceived handling qualities. Trim comparisons show improved correlation with flight test data when elastic modes are modeled. The results demonstrate the efficiency with which the mathematical modeling sophistication of existing simulation facilities can be upgraded using parallel processing, and the importance of these upgrades to simulation fidelity

    Ground-Based Astronomical Instrumentation Development in the United States: A White Paper on the Challenges Faced by the US Community

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    This invited white paper, submitted to the National Science Foundation in January of 2020, discusses the current challenges faced by the United States astronomical instrumentation community in the era of extremely large telescopes. Some details may have changed since submission, but the basic tenets are still very much valid. The paper summarizes the technical, funding, and personnel challenges the US community faces, provides an informal census of current instrumentation groups in the US, and compares the state-of-affairs in the US with that of the European community, which builds astronomical instruments from consortia of large hard-money funded instrument centers in a coordinated fashion. With the recent release of the Decadal Survey on Astronomy and Astrophysics 2020 (Astro2020), it is clear that strong community support exists for this next generation of large telescopes in the US. Is the US ready? Is there sufficient talent, facilities, and resources in the community today to meet the challenge of developing the complex suite of instruments envisioned for two US ELTs? These questions are addressed, along with thoughts on how the National Science Foundation can help build a more viable and stable instrumentation program in the US. These thoughts are intended to serve as a starting point for a broader discussion, with the end goal being a plan that puts the US astronomical instrumentation community on solid footing and poised to take on the challenges presented by the ambitious goals we have set in the era of ELTs.Comment: 22 pages, 1 table, 0 figures. This is an invited white paper submitted to the National Science Foundation in January of 202

    The Community Development Society Students and Young Professionals Initiative

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    There is a growing recognition of the role of youth in community development. Their roles range from serving on youth committees in local development organization to training for careers in the community development profession (e.g., Brennan, Barnett, & Lesmeister, 2007; Christens & Dolan, 2011). Thus, encouraging young professionals and graduate students to become members in professional associations or organizations is crucial for networking, professional development, and collaborative efforts towards community development. In an attempt to bridge potential pitfalls associated with student involvement in a professional association, an ad hoc meeting of graduate students and young professionals was convened at the annual conference of the Community Development Society (CDS) in July 2017. The discussion eventually blossomed into an initiative which created an opportunity to explore best practices for CDS to make students and young professionals feel included and welcomed. The participants discussed best practices for enhancing the culture of the association based on their lived experiences. Furthermore, these discussions revealed four major barriers in participating in a professional association which include lack of monetary funds, self-examination of “doing” community development, practitioners vs. academics, and the overall benefits of belonging to the association and attending the conference

    Perceptions of Grief Education in Accredited Counseling Programs: Recommendations for Counselor Education

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    As grief can be considered a critical life event, unresolved grief can interfere with quality of life, affecting lifestyle, behavior, emotional strength, and cognitive function. Unresolved grief can even result in suicidal ideation. Counselors can and often do work with grief issues in clients and can promote positive outcomes for grieving clients by addressing personal loss and helping clients process grief related issues. This study was based on an analysis of students within counseling programs accredited by the Council for Accreditation of Counseling and Related Educational Programs based on earlier research conducted by one of the authors. Self-perception of competency in counseling clients who are having grief-related issues from loss was assessed using the Grief Counseling Competency Scale. By analyzing results of the Grief Counseling Competency Scale, participants showed a need for further training in grief counseling skills and theory. Results and implications of the quantitative analysis as well as suggestions for further study are discussed

    TAKE-OFF FORCES AND IMPULSES IN THE LONG JUMP

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    A series of jumps by an experienced female athlete were recorded with a force platform and a high-speed video camera. We obtained a wide range of run-up velocities by using direct intervention to set the length of the athlete’s run-up. In all jumps the horizontal take-off force was predominantly a backwards braking force and so the athlete’s horizontal velocity was substantially reduced during the take-off. The athlete’s breaking impulse increased with increasing run-up velocity, but not so much as to negate the increase in run-up velocity. The optimum long jump take-off technique is a compromise between the conflicting desires of generating vertical impulse and minimising the horizontal braking impulse. We currently have no firm recommendation as to the usefulness of a force platform in improving an athlete’s take-off technique

    Dwarf Galaxy Dark Matter Density Profiles Inferred from Stellar and Gas Kinematics

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    We present new constraints on the density profiles of dark matter (DM) halos in seven nearby dwarf galaxies from measurements of their integrated stellar light and gas kinematics. The gas kinematics of low mass galaxies frequently suggest that they contain constant density DM cores, while N-body simulations instead predict a cuspy profile. We present a data set of high resolution integral field spectroscopy on seven galaxies and measure the stellar and gas kinematics simultaneously. Using Jeans modeling on our full sample, we examine whether gas kinematics in general produce shallower density profiles than are derived from the stars. Although 2/7 galaxies show some localized differences in their rotation curves between the two tracers, estimates of the central logarithmic slope of the DM density profile, gamma, are generally robust. The mean and standard deviation of the logarithmic slope for the population are gamma=0.67+/-0.10 when measured in the stars and gamma=0.58+/-0.24 when measured in the gas. We also find that the halos are not under concentrated at the radii of half their maximum velocities. Finally, we search for correlations of the DM density profile with stellar velocity anisotropy and other baryonic properties. Two popular mechanisms to explain cored DM halos are an exotic DM component or feedback models that strongly couple the energy of supernovae into repeatedly driving out gas and dynamically heating the DM halos. We investigate correlations that may eventually be used to test models. We do not find a secondary parameter that strongly correlates with the central DM density slope, but we do find some weak correlations. Determining the importance of these correlations will require further model developments and larger observational samples. (Abridged)Comment: 29 pages, 18 figures, 10 tables, accepted for publication in Ap

    The diet-derived short chain fatty acid propionate improves beta-cell function in humans and stimulates insulin secretion from human islets in vitro

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    Aims: Diet-derived short chain fatty acids (SCFAs) improve glucose homeostasis in vivo, but the role of individual SCFAs and their mechanisms of action have not been defined. This study evaluated the effects of increasing colonic delivery of the SCFA propionate on β-cell function in humans and the direct effects of propionate on isolated human islets in vitro. Materials and Methods: For 24 weeks human subjects ingested an inulin-propionate ester that delivers propionate to the colon. Acute insulin, GLP-1 and non-esterified fatty acid (NEFA) levels were quantified pre- and post-supplementation in response to a mixed meal test. Expression of the SCFA receptor FFAR2 in human islets was determined by western blotting and immunohistochemistry. Dynamic insulin secretion from perifused human islets was quantified by radioimmunoassay and islet apoptosis was determined by quantification of caspase 3/7 activities. Results: Colonic propionate delivery in vivo was associated with improved β-cell function with increased insulin secretion that was independent of changes in GLP-1 levels. Human islet β-cells expressed FFAR2 and propionate potentiated dynamic glucose-stimulated insulin secretion in vitro, an effect that was dependent on signalling via protein kinase C. Propionate also protected human islets from apoptosis induced by the NEFA sodium palmitate and inflammatory cytokines. Conclusions: Our results indicate that propionate has beneficial effects on β-cell function in vivo, and in vitro analyses demonstrated that it has direct effects to potentiate glucose-stimulated insulin release and maintain β-cell mass through inhibition of apoptosis. These observations support ingestion of propiogenic dietary fibres to maintain healthy glucose homeostasis

    The VIRUS-P Exploration of Nearby Galaxies (VENGA): Survey Design and First Results

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    VENGA is a large-scale extragalactic IFU survey, which maps the bulges, bars and large parts of the outer disks of 32 nearby normal spiral galaxies. The targets are chosen to span a wide range in Hubble types, star formation activities, morphologies, and inclinations, at the same time of having vast available multi-wavelength coverage from the far-UV to the mid-IR, and available CO and 21cm mapping. The VENGA dataset will provide 2D maps of the SFR, stellar and gas kinematics, chemical abundances, ISM density and ionization states, dust extinction and stellar populations for these 32 galaxies. The uniqueness of the VIRUS-P large field of view permits these large-scale mappings to be performed. VENGA will allow us to correlate all these important quantities throughout the different environments present in galactic disks, allowing the conduction of a large number of studies in star formation, structure assembly, galactic feedback and ISM in galaxies.Comment: 7 pages, 3 figures, proceedings of the "Third Biennial Frank N. Bash Symposium, New Horizons in Astronomy" held in Austin, TX, Oct. 2009. To be published in the Astronomical Society of the Pacific Conference Series, eds. L. Stanford, L. Hao, Y. Mao, J. Gree
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