559 research outputs found

    Space Station Freedom automation and robotics: An assessment of the potential for increased productivity

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    This report presents the results of a study performed in support of the Space Station Freedom Advanced Development Program, under the sponsorship of the Space Station Engineering (Code MT), Office of Space Flight. The study consisted of the collection, compilation, and analysis of lessons learned, crew time requirements, and other factors influencing the application of advanced automation and robotics, with emphasis on potential improvements in productivity. The lessons learned data collected were based primarily on Skylab, Spacelab, and other Space Shuttle experiences, consisting principally of interviews with current and former crew members and other NASA personnel with relevant experience. The objectives of this report are to present a summary of this data and its analysis, and to present conclusions regarding promising areas for the application of advanced automation and robotics technology to the Space Station Freedom and the potential benefits in terms of increased productivity. In this study, primary emphasis was placed on advanced automation technology because of its fairly extensive utilization within private industry including the aerospace sector. In contrast, other than the Remote Manipulator System (RMS), there has been relatively limited experience with advanced robotics technology applicable to the Space Station. This report should be used as a guide and is not intended to be used as a substitute for official Astronaut Office crew positions on specific issues

    Measuring the Intrapersonal Component of Psychological Empowerment: Confirmatory Factor Analysis of the Sociopolitical Control Scale

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    The Sociopolitical Control Scale (SPCS) is a widely used measure of the intrapersonal component of psychological empowerment. Confirmatory factor analyses (CFA) were conducted with data from two samples to test the hypothesized structure of the SPCS, the potential effects of method bias on the measure's psychometric properties, and whether a revised version of the scale (SPCS‐R) yielded improved model fit. Sample 1 included 316 randomly selected community residents of the Midwestern United States. Sample 2 included 750 community residents of the Northeastern U.S. Results indicated that method bias from the use of negatively worded items had a significant effect on the factor structure of the SPCS. CFA of the SPCS‐R, in which negatively worded items were rephrased so that all statements were positively worded, supported the measure's hypothesized two‐factor structure (i.e., leadership competence and policy control). Subscales of the SPCS‐R were found reliable and related in expected ways with measures of community involvement. Implications of the study for empowerment‐based research and practice are described, and strategies to further develop the SPCS are discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/117223/1/ajcp9070.pd

    Numerical modeling of CLT diaphragms tested on a shake-table experiment

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    Current standards and existing literature provide very limited information regarding the design of cross-laminated timber (CLT) floor diaphragms. In addition, limited procedures exist to develop analytical models to estimate the deformation response of CLT floor diaphragms. This paper presents a modelling approach that captures the response of CLT timber diaphragms, with a special focus on CLT spline panel-to-panel connections. The modeling approach is validated through the comparison of the results of the computation model with experimental data obtained from a series of shake-tables test performed on a two-story full-scale building tested in the summer of 2017 at UC San Diego Large High Performance Outdoor Shake Table. The two-story building included two diaphragm designs at each floor level. The first solution consists of CLT panels connected with plywood surface splines that are fastened using self-tapping screws, while the second consists of a CLT-concrete composite floor solution. Results from the nonlinear pushover analysis describe accurately the experimental data obtained.(undefined

    Voluntary exercise can strengthen the circadian system in aged mice

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    Consistent daily rhythms are important to healthy aging according to studies linking disrupted circadian rhythms with negative health impacts. We studied the effects of age and exercise on baseline circadian rhythms and on the circadian system's ability to respond to the perturbation induced by an 8 h advance of the light:dark (LD) cycle as a test of the system's robustness. Mice (male, mPer2luc/C57BL/6) were studied at one of two ages: 3.5 months (n = 39) and >18 months (n = 72). We examined activity records of these mice under entrained and shifted conditions as well as mPER2::LUC measures ex vivo to assess circadian function in the suprachiasmatic nuclei (SCN) and important target organs. Age was associated with reduced running wheel use, fragmentation of activity, and slowed resetting in both behavioral and molecular measures. Furthermore, we observed that for aged mice, the presence of a running wheel altered the amplitude of the spontaneous firing rate rhythm in the SCN in vitro. Following a shift of the LD cycle, both young and aged mice showed a change in rhythmicity properties of the mPER2::LUC oscillation of the SCN in vitro, and aged mice exhibited longer lasting internal desynchrony. Access to a running wheel alleviated some age-related changes in the circadian system. In an additional experiment, we replicated the effect of the running wheel, comparing behavioral and in vitro results from aged mice housed with or without a running wheel (>21 months, n = 8 per group, all examined 4 days after the shift). The impact of voluntary exercise on circadian rhythm properties in an aged animal is a novel finding and has implications for the health of older people living with environmentally induced circadian disruption

    Analytical and Numerical Models for Wind and Seismic Design and Assessment of Mass Timber Diaphragms

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    While the use of cross-laminated timber (CLT) panels for building construction has increased over the last several decades, current standards and existing literature provide limited information regarding the design of CLT diaphragms or the prediction of their deflections when subjected to wind and strong earthquake motions. This paper presents the design and assessment of a CLT diaphragm that was part of a full-scale two-story structure subjected to shake-table testing. An analytical model is proposed for diaphragm deflection accounting for in-plane shear and bending stiffness, as well as the stiffness of various connections. Moreover, a refined numerical modeling strategy is proposed in order to consider phenomena such as panel-to-panel gap closure. Results indicate that the analytical model yields conservative results both in terms of deflections and forces when compared to the numerical model that simulates similar sources of strength and stiffness. The analytical model is suitable for the design of symmetric diaphragms with regular shapes, whereas the numerical model can also be used to model asymmetric diaphragms with irregular shapes

    A Comparison of Administrative and Physiologic Predictive Models in Determining Risk Adjusted Mortality Rates in Critically Ill Patients

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    Hospitals are increasingly compared based on clinical outcomes adjusted for severity of illness. Multiple methods exist to adjust for differences between patients. The challenge for consumers of this information, both the public and healthcare providers, is interpreting differences in risk adjustment models particularly when models differ in their use of administrative and physiologic data. We set to examine how administrative and physiologic models compare to each when applied to critically ill patients.We prospectively abstracted variables for a physiologic and administrative model of mortality from two intensive care units in the United States. Predicted mortality was compared through the Pearsons Product coefficient and Bland-Altman analysis. A subgroup of patients admitted directly from the emergency department was analyzed to remove potential confounding changes in condition prior to ICU admission.We included 556 patients from two academic medical centers in this analysis. The administrative model and physiologic models predicted mortalities for the combined cohort were 15.3% (95% CI 13.7%, 16.8%) and 24.6% (95% CI 22.7%, 26.5%) (t-test p-value<0.001). The r(2) for these models was 0.297. The Bland-Atlman plot suggests that at low predicted mortality there was good agreement; however, as mortality increased the models diverged. Similar results were found when analyzing a subgroup of patients admitted directly from the emergency department. When comparing the two hospitals, there was a statistical difference when using the administrative model but not the physiologic model. Unexplained mortality, defined as those patients who died who had a predicted mortality less than 10%, was a rare event by either model.In conclusion, while it has been shown that administrative models provide estimates of mortality that are similar to physiologic models in non-critically ill patients with pneumonia, our results suggest this finding can not be applied globally to patients admitted to intensive care units. As patients and providers increasingly use publicly reported information in making health care decisions and referrals, it is critical that the provided information be understood. Our results suggest that severity of illness may influence the mortality index in administrative models. We suggest that when interpreting "report cards" or metrics, health care providers determine how the risk adjustment was made and compares to other risk adjustment models

    Black Hole Spin via Continuum Fitting and the Role of Spin in Powering Transient Jets

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    The spins of ten stellar black holes have been measured using the continuum-fitting method. These black holes are located in two distinct classes of X-ray binary systems, one that is persistently X-ray bright and another that is transient. Both the persistent and transient black holes remain for long periods in a state where their spectra are dominated by a thermal accretion disk component. The spin of a black hole of known mass and distance can be measured by fitting this thermal continuum spectrum to the thin-disk model of Novikov and Thorne; the key fit parameter is the radius of the inner edge of the black hole's accretion disk. Strong observational and theoretical evidence links the inner-disk radius to the radius of the innermost stable circular orbit, which is trivially related to the dimensionless spin parameter a_* of the black hole (|a_*| < 1). The ten spins that have so far been measured by this continuum-fitting method range widely from a_* \approx 0 to a_* > 0.95. The robustness of the method is demonstrated by the dozens or hundreds of independent and consistent measurements of spin that have been obtained for several black holes, and through careful consideration of many sources of systematic error. Among the results discussed is a dichotomy between the transient and persistent black holes; the latter have higher spins and larger masses. Also discussed is recently discovered evidence in the transient sources for a correlation between the power of ballistic jets and black hole spin.Comment: 30 pages. Accepted for publication in Space Science Reviews. Also to appear in hard cover in the Space Sciences Series of ISSI "The Physics of Accretion onto Black Holes" (Springer Publisher). Changes to Sections 5.2, 6.1 and 7.4. Section 7.4 responds to Russell et al. 2013 (MNRAS, 431, 405) who find no evidence for a correlation between the power of ballistic jets and black hole spi

    Comparative mapping of expressed sequence tags containing microsatellites in rainbow trout (Oncorhynchus mykiss)

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    BACKGROUND: Comparative genomics, through the integration of genetic maps from species of interest with whole genome sequences of other species, will facilitate the identification of genes affecting phenotypes of interest. The development of microsatellite markers from expressed sequence tags will serve to increase marker densities on current salmonid genetic maps and initiate in silico comparative maps with species whose genomes have been fully sequenced. RESULTS: Eighty-nine polymorphic microsatellite markers were generated for rainbow trout of which at least 74 amplify in other salmonids. Fifty-five have been associated with functional annotation and 30 were mapped on existing genetic maps. Homologous sequences were identified for 20 of the EST containing microsatellites to identify comparative assignments within the tetraodon, mouse, and/or human genomes. CONCLUSION: The addition of microsatellite markers constructed from expressed sequence tag data will facilitate the development of high-density genetic maps for rainbow trout and comparative maps with other salmonids and better studied species

    Population Genetics of GYPB and Association Study between GYPB*S/s Polymorphism and Susceptibility to P. falciparum Infection in the Brazilian Amazon

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    Merozoites of Plasmodium falciparum invade through several pathways using different RBC receptors. Field isolates appear to use a greater variability of these receptors than laboratory isolates. Brazilian field isolates were shown to mostly utilize glycophorin A-independent invasion pathways via glycophorin B (GPB) and/or other receptors. The Brazilian population exhibits extensive polymorphism in blood group antigens, however, no studies have been done to relate the prevalence of the antigens that function as receptors for P. falciparum and the ability of the parasite to invade. Our study aimed to establish whether variation in the GYPB*S/s alleles influences susceptibility to infection with P. falciparum in the admixed population of Brazil.Two groups of Brazilian Amazonians from Porto Velho were studied: P. falciparum infected individuals (cases); and uninfected individuals who were born and/or have lived in the same endemic region for over ten years, were exposed to infection but have not had malaria over the study period (controls). The GPB Ss phenotype and GYPB*S/s alleles were determined by standard methods. Sixty two Ancestry Informative Markers were genotyped on each individual to estimate admixture and control its potential effect on the association between frequency of GYPB*S and malaria infection.GYPB*S is associated with host susceptibility to infection with P. falciparum; GYPB*S/GYPB*S and GYPB*S/GYPB*s were significantly more prevalent in the in the P. falciparum infected individuals than in the controls (69.87% vs. 49.75%; P<0.02). Moreover, population genetics tests applied on the GYPB exon sequencing data suggest that natural selection shaped the observed pattern of nucleotide diversity.Epidemiological and evolutionary approaches suggest an important role for the GPB receptor in RBC invasion by P. falciparum in Brazilian Amazons. Moreover, an increased susceptibility to infection by this parasite is associated with the GPB S+ variant in this population

    America's Rural Hospitals: A Selective Review of 1980s Research

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    We review 1980s research on American rural hospitals within the context of a decade of increasing restrictiveness in the reimbursement and operating environments. Areas addressed include rural hospital definitions, organizational and financial performance, and strategic management activities. The latter category consists of hospital closure, diversification and vertical integration, swing-bed conversion, sole community provider designation, horizontal integration and multihospital system affiliation, marketing, and patient retention. The review suggests several research needs, including: developing more meaningful definitions of rural hospitals, engaging in methodologically sound work on the effects of innovative programs and strategic management activities—including conversion of the facility itself—on rural hospital performance, and completing studies of the effects of rural hospital closure or conversion on the health of the communities served.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74857/1/j.1748-0361.1990.tb00682.x.pd
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