705 research outputs found

    An investigation of cotton for parachute cloth

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    This is a resume of the work of the Bureau of Standards on a cotton parachute cloth for use as a substitute for silk in the event of an emergency curtailing the supply. Cotton yarn of high strength in proportion to its weight and otherwise specially suitable for parachute cloth was developed. Cloth woven from this yarn in the bureau mill was equal or superior to parachute silk in strength and tear resistance, met the requirements with respect to air permeability, and weighed only a few tenths of an ounce per square yard more than the silk cloth. Practical trials of cotton parachutes carried out by the Navy Department clearly indicate that the cotton parachute closely approaches the silk parachute in performance as to rate of descent, opening time, strength and ability to function when stored in the pack for sixty days. The increase in weight of the equipment resulting from the use of cotton cloth instead of silk is considered to be well within practicable limits. A specification for cotton parachute cloth and the way in which the requirements of the specification have been met are given. Cotton yarns suitable for parachute cloth are now being woven commercially in the United States

    Update on the correlation of the highest energy cosmic rays with nearby extragalactic matter

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    Data collected by the Pierre Auger Observatory through 31 August 2007 showed evidence for anisotropy in the arrival directions of cosmic rays above the Greisen-Zatsepin-Kuz'min energy threshold, \nobreak{6×10196\times 10^{19}eV}. The anisotropy was measured by the fraction of arrival directions that are less than 3.13.1^\circ from the position of an active galactic nucleus within 75 Mpc (using the V\'eron-Cetty and V\'eron 12th12^{\rm th} catalog). An updated measurement of this fraction is reported here using the arrival directions of cosmic rays recorded above the same energy threshold through 31 December 2009. The number of arrival directions has increased from 27 to 69, allowing a more precise measurement. The correlating fraction is (386+7)(38^{+7}_{-6})%, compared with 2121% expected for isotropic cosmic rays. This is down from the early estimate of (6913+11)(69^{+11}_{-13})%. The enlarged set of arrival directions is examined also in relation to other populations of nearby extragalactic objects: galaxies in the 2 Microns All Sky Survey and active galactic nuclei detected in hard X-rays by the Swift Burst Alert Telescope. A celestial region around the position of the radiogalaxy Cen A has the largest excess of arrival directions relative to isotropic expectations. The 2-point autocorrelation function is shown for the enlarged set of arrival directions and compared to the isotropic expectation.Comment: Accepted for publication in Astroparticle Physics on 31 August 201

    Renal replacement therapy in acute kidney injury: controversy and consensus

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    Renal replacement therapies (RRTs) represent a cornerstone in the management of severe acute kidney injury. This area of intensive care and nephrology has undergone significant improvement and evolution in recent years. Continuous RRTs have been a major focus of new technological and treatment strategies. RRT is being used increasingly in the intensive care unit, not only for renal indications but also for other organ-supportive strategies. Several aspects related to RRT are now well established, but others remain controversial. In this review, we review the available RRT modalities, covering technical and clinical aspects. We discuss several controversial issues, provide some practical recommendations, and where possible suggest a research agenda for the future

    Search for First Harmonic Modulation in the Right Ascension Distribution of Cosmic Rays Detected at the Pierre Auger Observatory

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    We present the results of searches for dipolar-type anisotropies in different energy ranges above 2.5×10172.5\times 10^{17} eV with the surface detector array of the Pierre Auger Observatory, reporting on both the phase and the amplitude measurements of the first harmonic modulation in the right-ascension distribution. Upper limits on the amplitudes are obtained, which provide the most stringent bounds at present, being below 2% at 99% C.L.C.L. for EeV energies. We also compare our results to those of previous experiments as well as with some theoretical expectations.Comment: 28 pages, 11 figure

    Gender and race do not alter early-life determinants of clinical disease progression in HIV-1 vertically infected children.

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    Objective: To identify early life predictors of clinical progression before and beyond age 1 year. Design: Prospective follow-up of 161 vertically HIV infected children in the ongoing European Collaborative Study provided data from birth over 16 years. Methods: Kaplan-Meier and Cox regression procedures were used to assess the predictive value of first available laboratory and clinical markers for progression defined as serious disease or death. We investigate gender and race effects on associations and the optimal threshold for longitudinal CD4+ percentage measurements after age 6 months for predicting disease progression. Results: Earliest (during the first 6 months) measurements of CD4+ percentage below 20% [three-fold increased risk (P = 0.041)] and absolute lymphocytes (AL) (reduction of risk of three-quarters for a one log increase (P =0.014)) were independently associated with overall and rapid disease progression during the first year. Persistent lymphadenopathy (or hepatomegaly) in early life was also additionally associated with overall disease progression, and after age 1 year [greater than doubling of risk, (P = 0.040)], but not with rapid progression. Associations were not significantly dependent on gender or race. CD4+ percentage of 10% was the best prognostic cut-off. Conclusions: Early clinical markers are strongly predictive of disease progression after 1 year of age into adolescence. However, rapid progression is less straightforward to predict, probably due largely to early progression during the first few months in such individuals. The independently predictive value of AL measurements suggest they could be used alone in the management of children in resource-poor settings

    Intensity Dependence of Multiple Orbital Contributions and Shape Resonance in High-Order Harmonic Generation of Aligned N₂ Molecules

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    We report measurements and theoretical simulations of high-order harmonic generation (HHG) in aligned N₂ molecules using a 1200-nm intense laser field when the generating pulse is perpendicular to the aligning one. With increasing laser intensity, the minimum in the HHG spectra first shifts its position and then disappears. Theoretical simulations including the macroscopic propagation effects in the medium reproduce these observations and the disappearance of the minimum is attributed to the additional contribution of HHG from inner orbitals. We also predict that the well-known shape resonance in the photoionization spectra of N₂ should exist in the HHG spectra. It is most clearly seen when the generating laser is parallel to the aligning one and disappears gradually as the angle between the two lasers increases. No clear evidence of this shape resonance has been reported so far when using lasers with different wavelengths. Further experimentation is needed to draw conclusions

    Integrating Trauma and Violence Informed Care in Primary Health Care Settings for First Nations Women Experiencing Violence: A Systematic Review

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    It is imperative that access to primary health care services is equitable as health care practitioners are often the first responders to women who experience violence. This is of particular importance for First Nations women who disproportionately experience interpersonal and structural violence when compared to non-First Nations women, as well as the ongoing impact of colonization, racism, and intergenerational trauma. To understand how primary health care services can provide equitable and effective care for First Nations women, we explored how trauma and violence informed care is integrated in primary health care settings through the lens of an equity-oriented framework. A systematic search of electronic databases included Medline (via Ovid), Scopus, Informit, and PubMed and grey literature. Six studies were included in the review and we undertook a narrative synthesis using the equity-oriented framework to draw together the intersection of trauma and violence informed care with culturally safe and contextually tailored care. This review demonstrates how equity-oriented primary health care settings respond to the complex and multiple forms of violence and intergenerational trauma experienced by First Nations women and thus mitigate shame and stigma to encourage disclosure and help seeking. Key attributes include responding to women’s individual contexts by centering family, engaging elders, encouraging community ownership, which is driven by a culturally competent workforce that builds trust, reduces retraumatization, and respects confidentiality. This review highlights the importance of strengthening and supporting the workforce, as well as embedding cultural safety within intersectoral partnerships and ensuring adequate resourcing and sustainability of initiatives

    Computational modeling with spiking neural networks

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    This chapter reviews recent developments in the area of spiking neural networks (SNN) and summarizes the main contributions to this research field. We give background information about the functioning of biological neurons, discuss the most important mathematical neural models along with neural encoding techniques, learning algorithms, and applications of spiking neurons. As a specific application, the functioning of the evolving spiking neural network (eSNN) classification method is presented in detail and the principles of numerous eSNN based applications are highlighted and discussed
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