1,666 research outputs found

    X-ray production in low energy proton stopping

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    The X-ray yields of stopping protons in an iron-nickel-cobalt alloy are calculated for use in predicting radiation damage in encased electronic devices

    A Geospatial Analysis of CDC-funded HIV Prevention Programs for African Americans in the United States

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    Given the increase in HIV/AIDS infection rates among racial and ethnic minorities, particularly African Americans, this study was undertaken as part of a larger research effort to examine the distribution of HIV prevention services focusing on African American populations within the United States. Data were gathered via a national survey of community-based organizations (CBOs) funded by the Centers for Disease Control and Prevention (CDC). A geocoded national database was constructed to identify, locate, and map these HIV prevention programs. A total of 1,020 CBOs responded to the survey, yielding a response rate of 70.3%. These CBOs administered a total of 3,028 HIV prevention programs. Data describing intervention types and persons served, combined with the address and service area of responding CBOs, were integrated with census data (2000) and analyzed by using a geographic information system (GIS). The results of our national level analysis show that HIV prevention services for African Americans have fair coverage where African Americans comprise a substantial proportion of the population in urban areas in northeastern states, but that HIV prevention services for African Americans are inadequately distributed in the southeastern states. A local-level analysis was conducted for Alabama, where 68% of HIV/AIDS cases are among African Americans. Specific interventions such as street and community outreach, health communications, and public information are fairly well provided to African Americans in more urban cities in Alabama, however, individual- and group-level interventions have poor coverage in rural areas where a large percentage of African-Americans live. Overall, our study illustrates that the use of GIS adds value when used with other data sources to provide prevention services that are accessible to the populations most in need

    Topological properties of punctual Hilbert schemes of almost-complex fourfolds (I)

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    In this article, we study topological properties of Voisin's punctual Hilbert schemes of an almost-complex fourfold XX. In this setting, we compute their Betti numbers and construct Nakajima operators. We also define tautological bundles associated with any complex bundle on XX, which are shown to be canonical in KK-theory

    Snapshot: a safety climate survey

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    This report provides a list of the scales and items contained in the Snapshot survey referred to in Fogarty, G. J., Cooper, R., & McMahon, S. (2018): 'A demands-resources view of safety climate in military aviation' due to appear in the journal Aviation Psychology and Applied Human Factors. Snapshot is administered annually by Australia's Directorate of Defence Aviation and Air Force Safety (DDAAFS) to personnel within the Royal Australian Air Force, the New Zealand Air Force, and selected Australian Army and Navy aviation-related elements. Snapshot was first introduced in 2013 in an effort to strengthen the organisations surveillance of safety culture. It has been designed to support managers (referred to as Commanders within a military context) in the management and enhancement of safety climate. Safety climate and the overall health of an organisation are tightly interwoven. In recognition of this interdependence, Snapshot seeks to provide managers with a holistic picture of their work group by breaking down the pathways and components that contribute to a wide range of organisational outcomes

    Rate of change in abdominal aortic aneurysm diameter after endovascular repair

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    AbstractObjective: Untreated abdominal aortic aneurysms (AAAs) enlarge at a mean rate of 3.9 mm/y with great individual variability. We sought to determine the effect of endovascular repair on the rate of change in aneurysm size. Methods: There were 110 patients who underwent endovascular AAA repair at Stanford University Medical Center and who were followed up for 1 to 30 months (mean, 10 months) with serial contrast-infused helical computed tomography (CT). Maximal aneurysm diameter was determined using two independent methods: (1) measured manually, from cross-sectional computed tomography (XSCT) angiograms and (2) calculated from quantitative three-dimensional computed tomography (3DCT) data as orthonormal diameter. Results: Maximal cross-sectional aneurysm diameter measured by hand (XSCT) and calculated as orthonormal values (3DCT) correlated closely (r = 0.915; P <.001). The XSCT-measured diameter was larger by 2.3 ± 3.75 mm (P <.001), and the 95% CI for SE of the bias was 1.85 to 2.75 mm. Preoperative aneurysm diameter (XSCT 59.1 ± 8.4 mm; 3DCT 58.1 ± 9.3 mm) did not differ significantly from the initial postoperative diameter. Considering all patients, XSCT diameter decreased at a rate of 0.34 ± 0.69 mm/mo, and 3DCT diameter decreased at a rate of 0.28 ± 0.79 mm/mo. Aneurysms in patients without endoleaks had a higher rate of decrease, an XSCT diameter by 0.50 ± 0.74 mm/mo, and 3DCT diameter by 0.46 ± 0.84 mm/mo. In these patients, mean absolute decrease in diameter at 6 months was 3.4 ± 4.5 mm (XSCT) and 3.3 ± 5.9 mm (3DCT) and at 12 months, 5.9 ± 5.7 mm (XSCT) and 5.4 ± 5.7 mm (3DCT). Aneurysms in patients with persistent endoleaks did not change in mean XSCT diameter, and 3DCT diameter increased by 0.12 ± 0.52 mm/mo (not significant). Aneurysm diameter remained within 4 mm of original size in 68% (3DCT) to 71% (XSCT) of patients. In one patient, aneurysm diameter increased (XSCT and 3DCT) more than 5 mm. Four patients who had a new onset endoleak had a much higher expansion rate than those with a chronic endoleak (P <.05). Conclusions: The rate of decrease in aneurysm size (annualized 3.4-4.1 mm/y) after endovascular repair of AAA approximates the reported expansion rate in untreated aneurysms. However, individual aneurysm behavior is unpredictable, and the presence of an endoleak is unreliable in predicting changes in diameter. New onset endoleaks are associated with an enlargement rate greater than that of untreated aneurysms. (J Vasc Surg 2000;32:108-15.

    Quantum Readiness in Healthcare and Public Health: Building a Quantum Literate Workforce

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    Quantum technologies, including quantum computing, cryptography, and sensing, among others, are set to revolutionize sectors ranging from materials science to drug discovery. Despite their significant potential, the implications for public health have been largely overlooked, highlighting a critical gap in recognition and preparation. This oversight necessitates immediate action, as public health remains largely unaware of quantum technologies as a tool for advancement. The application of quantum principles to epidemiology and health informatics, termed quantum health epidemiology and quantum health informatics, has the potential to radically transform disease surveillance, prediction, modeling, and analysis of health data. However, there is a notable lack of quantum expertise within the public health workforce and educational pipelines. This gap underscores the urgent need for the development of quantum literacy among public health practitioners, leaders, and students to leverage emerging opportunities while addressing risks and ethical considerations. Innovative teaching methods, such as interactive simulations, games, visual models, and other tailored platforms, offer viable solutions for bridging knowledge gaps without the need for advanced physics or mathematics. However, the opportunity to adapt is fleeting as the quantum era in healthcare looms near. It is imperative that public health urgently focuses on updating its educational approaches, workforce strategies, data governance, and organizational culture to proactively meet the challenges of quantum disruption thereby becoming quantum ready.Comment: 13 pages, 1 tabl

    Recovering the second moment of the strain distribution from neutron Bragg edge data

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    Point by point strain scanning is often used to map the residual stress (strain) in engineering materials and components. However, the gauge volume and hence spatial resolution is limited by the beam defining apertures and can be anisotropic for very low and high diffraction (scattering) angles. Alternatively, wavelength resolved neutron transmission imaging has a potential to retrieve information tomographically about residual strain induced within materials through measurement in transmission of Bragg edges - crystallographic fingerprints whose locations and shapes depend on microstructure and strain distribution. In such a case the spatial resolution is determined by the geometrical blurring of the measurement setup and the detector point spread function. Mathematically, reconstruction of strain tensor field is described by the longitudinal ray transform; this transform has a non-trivial null-space, making direct inversion impossible. A combination of the longitudinal ray transform with physical constraints was used to reconstruct strain tensor fields in convex objects. To relax physical constraints and generalise reconstruction, a recently introduced concept of histogram tomography can be employed. Histogram tomography relies on our ability to resolve the distribution of strain in the beam direction, as we discuss in the paper. More specifically, Bragg edge strain tomography requires extraction of the second moment (variance about zero) of the strain distribution which has not yet been demonstrated in practice. In this paper we verify experimentally that the second moment can be reliably measured for a previously well characterised aluminium ring and plug sample. We compare experimental measurements against numerical calculation and further support our conclusions by rigorous uncertainty quantification of the estimated mean and variance of the strain distribution

    The SAMI Galaxy Survey: Asymmetry in Gas Kinematics and its links to Stellar Mass and Star Formation

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    We study the properties of kinematically disturbed galaxies in the SAMI Galaxy Survey using a quantitative criterion, based on kinemetry (Krajnovic et al.). The approach, similar to the application of kinemetry by Shapiro et al. uses ionised gas kinematics, probed by H{\alpha} emission. By this method 23+/-7% of our 360-galaxy sub-sample of the SAMI Galaxy Survey are kinematically asymmetric. Visual classifications agree with our kinemetric results for 90% of asymmetric and 95% of normal galaxies. We find stellar mass and kinematic asymmetry are inversely correlated and that kinematic asymmetry is both more frequent and stronger in low-mass galaxies. This builds on previous studies that found high fractions of kinematic asymmetry in low mass galaxies using a variety of different methods. Concentration of star forma- tion and kinematic disturbance are found to be correlated, confirming results found in previous work. This effect is stronger for high mass galaxies (log(M*) > 10) and indicates that kinematic disturbance is linked to centrally concentrated star formation. Comparison of the inner (within 0.5Re) and outer H{\alpha} equivalent widths of asymmetric and normal galaxies shows a small but significant increase in inner equivalent width for asymmetric galaxies.Comment: 29 pages, 21 figure

    Stability conditions and positivity of invariants of fibrations

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    We study three methods that prove the positivity of a natural numerical invariant associated to 11-parameter families of polarized varieties. All these methods involve different stability conditions. In dimension 2 we prove that there is a natural connection between them, related to a yet another stability condition, the linear stability. Finally we make some speculations and prove new results in higher dimension.Comment: Final version, to appear in the Springer volume dedicated to Klaus Hulek on the occasion of his 60-th birthda
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