5,922 research outputs found

    INTERESTS AND DECENT WORK’S ACCOUNT OF WELL-BEING AND JOB PERFORMANCE IN A LOWER SOCIAL CLASS SAMPLE

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    There is a need for more accurate information regarding the work-related experiences of individuals from lower social class backgrounds. The present study seeks to evaluate the degree to which important career-related variables (e.g., interest congruence, decent work) account for differences in subjective well-being (SWB) and job performance (e.g., occupational citizenship behavior [OCB], task performance) for a sample of adults from lower social class backgrounds. A novel approach to evaluating the objective indicators of social class for individual study participants was implemented to collect a sample of 365 participants, 105 of which were included in analysis. A path analysis was conducted to evaluate study hypotheses. Results indicated that decent work accounted for a significant amount of the variance in SWB, but not for task performance or OCB. Interest congruence did not account for a significant amount of the variance in any outcome variables. Practical implications of the results, study limitations, and next steps for research are discussed

    Experimental Findings and Numerical Simulations on Gasoline Fuel Injector System

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    https://deepblue.lib.umich.edu/bitstream/2027.42/154192/1/39015101405176.pd

    Body mass index and incident coronary heart disease in women: a population-based prospective study

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    BACKGROUND A high body mass index (BMI) is associated with an increased risk of mortality from coronary heart disease (CHD); however, a low BMI may also be associated with an increased mortality risk. There is limited information on the relation of incident CHD risk across a wide range of BMI, particularly in women. We examined the relation between BMI and incident CHD overall and across different risk factors of the disease in the Million Women Study. METHODS 1.2 million women (mean age=56 years) participants without heart disease, stroke, or cancer (except non-melanoma skin cancer) at baseline (1996 to 2001) were followed prospectively for 9 years on average. Adjusted relative risks and 20-year cumulative incidence from age 55 to 74 years were calculated for CHD using Cox regression. RESULTS After excluding the first 4 years of follow-up, we found that 32,465 women had a first coronary event (hospitalization or death) during follow-up. The adjusted relative risk for incident CHD per 5 kg/m2 increase in BMI was 1.23 (95% confidence interval (CI) 1.22 to 1.25). The cumulative incidence of CHD from age 55 to 74 years increased progressively with BMI, from 1 in 11 (95% CI 1 in 10 to 12) for BMI of 20 kg/m2, to 1 in 6(95% CI 1 in 5 to 7) for BMI of 34 kg/m2. A 10 kg/m2 increase in BMI conferred a similar risk to a 5-year increment in chronological age. The 20 year cumulative incidence increased with BMI in smokers and non-smokers, alcohol drinkers and non-drinkers, physically active and inactive, and in the upper and lower socioeconomic classes. In contrast to incident disease, the relation between BMI and CHD mortality (n=2,431) was J-shaped. For the less than 20 kg/m2 and ≥35 kg/m2 BMI categories, the respective relative risks were 1.27 (95% CI 1.06 to 1.53) and 2.84 (95% CI 2.51 to 3.21) for CHD deaths, and 0.89 (95% CI 0.83 to 0.94) and 1.85 (95% CI 1.78 to 1.92) for incident CHD. CONCLUSIONS CHD incidence in women increases progressively with BMI, an association consistently seen in different subgroups. The shape of the relation with BMI differs for incident and fatal disease.The Million Women Study is funded by Cancer Research UK, the Medical Research Council, and the NHS Breast Screening Programme. The funding organizations were not involved in the study design or conduct, data analysis or interpretation, manuscript preparation or review, final version approval, or decision to submit the manuscript

    HOGWILD!: A Lock-Free Approach to Parallelizing Stochastic Gradient Descent

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    Stochastic Gradient Descent (SGD) is a popular algorithm that can achieve state-of-the-art performance on a variety of machine learning tasks. Several researchers have recently proposed schemes to parallelize SGD, but all require performance-destroying memory locking and synchronization. This work aims to show using novel theoretical analysis, algorithms, and implementation that SGD can be implemented without any locking. We present an update scheme called HOGWILD! which allows processors access to shared memory with the possibility of overwriting each other's work. We show that when the associated optimization problem is sparse, meaning most gradient updates only modify small parts of the decision variable, then HOGWILD! achieves a nearly optimal rate of convergence. We demonstrate experimentally that HOGWILD! outperforms alternative schemes that use locking by an order of magnitude.Comment: 22 pages, 10 figure

    Cohomology of quantum groups: An analog of Kostant's Theorem

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    We prove the analog of Kostant's Theorem on Lie algebra cohomology in the context of quantum groups. We prove that Kostant's cohomology formula holds for quantum groups at a generic parameter qq, recovering an earlier result of Malikov in the case where the underlying semisimple Lie algebra g=sl(n)\mathfrak{g} = \mathfrak{sl}(n). We also show that Kostant's formula holds when qq is specialized to an ℓ\ell-th root of unity for odd ℓ≥h−1\ell \ge h-1 (where hh is the Coxeter number of g\mathfrak{g}) when the highest weight of the coefficient module lies in the lowest alcove. This can be regarded as an extension of results of Friedlander-Parshall and Polo-Tilouine on the cohomology of Lie algebras of reductive algebraic groups in prime characteristic.Comment: 12 page

    Optical Navigation Algorithm Performance

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    There is a wide variety of optical navigation (OpNav) techniques that can be used to extract observables from images of natural bodies. Each of these techniques has a number of strengths and weaknesses and domains where they are most applicable. In this paper, we compare the performance of some of the most commonly used OpNav techniques across a variety of orbital regimes and a variety of body types through the use of synthetic images. Specifically, we consider the techniques of analytic model fitting, phase corrected moment estimation, limb-scanning, ellipsoid matching, and cross correlation using synthetic images of a tri-axial ellipsoid, the asteroid Bennu, and the comet 67P/Churyumov-Gerasimenko. For each technique, regime, and body, we examine the overall accuracy and the type of information available. The resulting information provides a useful tool for understanding which techniques are best suited for a given image, as well as for understanding the relative performance of each technique

    An Empirically Derived Three-Dimensional Laplace Resonance in the Gliese 876 Planetary System

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    We report constraints on the three-dimensional orbital architecture for all four planets known to orbit the nearby M dwarf Gliese 876 based solely on Doppler measurements and demanding long-term orbital stability. Our dataset incorporates publicly available radial velocities taken with the ELODIE and CORALIE spectrographs, HARPS, and Keck HIRES as well as previously unpublished HIRES velocities. We first quantitatively assess the validity of the planets thought to orbit GJ 876 by computing the Bayes factors for a variety of different coplanar models using an importance sampling algorithm. We find that a four-planet model is preferred over a three-planet model. Next, we apply a Newtonian MCMC algorithm to perform a Bayesian analysis of the planet masses and orbits using an n-body model in three-dimensional space. Based on the radial velocities alone, we find that a 99% credible interval provides upper limits on the mutual inclinations for the three resonant planets (Φcb<6.20∘\Phi_{cb}<6.20^\circ for the "c" and "b" pair and Φbe<28.5∘\Phi_{be}<28.5^\circ for the "b" and "e" pair). Subsequent dynamical integrations of our posterior sample find that the GJ 876 planets must be roughly coplanar (Φcb<2.60∘\Phi_{cb}<2.60^\circ and Φbe<7.87∘\Phi_{be}<7.87^\circ), suggesting the amount of planet-planet scattering in the system has been low. We investigate the distribution of the respective resonant arguments of each planet pair and find that at least one argument for each planet pair and the Laplace argument librate. The libration amplitudes in our three-dimensional orbital model supports the idea of the outer-three planets having undergone significant past disk migration.Comment: 19 pages, 11 figures, 8 tables. Accepted to MNRAS. Posterior samples available at https://github.com/benelson/GJ87

    The 55 Cancri Planetary System: Fully Self-Consistent N-body Constraints and a Dynamical Analysis

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    We present an updated study of the planets known to orbit 55 Cancri A using 1,418 high-precision radial velocity observations from four observatories (Lick, Keck, Hobby-Eberly Telescope, Harlan J. Smith Telescope) and transit time/durations for the inner-most planet, 55 Cancri "e" (Winn et al. 2011). We provide the first posterior sample for the masses and orbital parameters based on self-consistent n-body orbital solutions for the 55 Cancri planets, all of which are dynamically stable (for at least 10810^8 years). We apply a GPU version of Radial velocity Using N-body Differential evolution Markov Chain Monte Carlo (RUN DMC; B. Nelson et al. 2014) to perform a Bayesian analysis of the radial velocity and transit observations. Each of the planets in this remarkable system has unique characteristics. Our investigation of high-cadence radial velocities and priors based on space-based photometry yields an updated mass estimate for planet "e" (8.09±0.268.09\pm0.26 M⊕_\oplus), which affects its density (5.51±1.001.325.51\pm^{1.32}_{1.00} g cm−3^{-3}) and inferred bulk composition. Dynamical stability dictates that the orbital plane of planet "e" must be aligned to within 60o60^o of the orbital plane of the outer planets (which we assume to be coplanar). The mutual interactions between the planets "b" and "c" may develop an apsidal lock about 180o180^o. We find 36-45% of all our model systems librate about the anti-aligned configuration with an amplitude of 51o±10o6o51^o\pm^{6^o}_{10^o}. Other cases showed short-term perturbations in the libration of ϖb−ϖc\varpi_b-\varpi_c, circulation, and nodding, but we find the planets are not in a 3:1 mean-motion resonance. A revised orbital period and eccentricity for planet "d" pushes it further toward the closest known Jupiter analog in the exoplanet population.Comment: 12 pages, 5 figures, 4 tables, accepted to MNRAS. Figure 2 (left) is updated from published version. Posterior samples available at http://www.personal.psu.edu/ben125/Downloads.htm

    A Novel Approach to Estimation of Patient-Specific Muscle Strength

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    Current modeling techniques have been used to model the Reverse Total Shoulder Arthroplasty (RTSA) to account for the geometric changes implemented after RTSA. Though these models have provided insight into the effects of geometric changes from RTSA these is still a limitation of understanding muscle function after RTSA on a patient-specific basis. The goal of this study sought to overcome this limitation by developing an approach to calibrate patient-specific muscle strength for an RTSA subject

    Vascular disease in women: comparison of diagnoses in hospital episode statistics and general practice records in England

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    BACKGROUND Electronic linkage to routine administrative datasets, such as the Hospital Episode Statistics (HES) in England, is increasingly used in medical research. Relatively little is known about the reliability of HES diagnostic information for epidemiological studies. In the United Kingdom (UK), general practitioners hold comprehensive records for individuals relating to their primary, secondary and tertiary care. For a random sample of participants in a large UK cohort, we compared vascular disease diagnoses in HES and general practice records to assess agreement between the two sources. METHODS Million Women Study participants with a HES record of hospital admission with vascular disease (ischaemic heart disease [ICD-10 codes I20-I25], cerebrovascular disease [G45, I60-I69] or venous thromboembolism [I26, I80-I82]) between April 1st 1997 and March 31st 2005 were identified. In each broad diagnostic group and in women with no such HES diagnoses, a random sample of about a thousand women was selected for study. We asked each woman's general practitioner to provide information on her history of vascular disease and this information was compared with the HES diagnosis record. RESULTS Over 90% of study forms sent to general practitioners were returned and 88% of these contained analysable data. For the vast majority of study participants for whom information was available, diagnostic information from general practice and HES records was consistent. Overall, for 93% of women with a HES diagnosis of vascular disease, general practice records agreed with the HES diagnosis; and for 97% of women with no HES diagnosis of vascular disease, the general practitioner had no record of a diagnosis of vascular disease. For severe vascular disease, including myocardial infarction (I21-22), stroke, both overall (I60-64) and by subtype, and pulmonary embolism (I26), HES records appeared to be both reliable and complete. CONCLUSION Hospital admission data in England provide diagnostic information for vascular disease of sufficient reliability for epidemiological analyses.The Million Women Study is funded by Cancer Research UK and the UK Medical Research Council. The study is registered with the NHS National Institute of Health Research Portfolio (study number 6862). General practices were reimbursed for conducting the data collection through NHS Service Support Cost funding of the National Institute of Health Research
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