2,063 research outputs found

    Heliospheric Transport of Neutron-Decay Protons

    Get PDF
    We report on new simulations of the transport of energetic protons originating from the decay of energetic neutrons produced in solar flares. Because the neutrons are fast-moving but insensitive to the solar wind magnetic field, the decay protons are produced over a wide region of space, and they should be detectable by current instruments over a broad range of longitudes for many hours after a sufficiently large gamma-ray flare. Spacecraft closer to the Sun are expected to see orders-of magnitude higher intensities than those at the Earth-Sun distance. The current solar cycle should present an excellent opportunity to observe neutron-decay protons with multiple spacecraft over different heliographic longitudes and distances from the Sun.Comment: 12 pages, 4 figures, to be published in special issue of Solar Physic

    Park characteristics, use, and physical activity: A review of studies using SOPARC (System for Observing Play and Recreation in Communities)

    Get PDF
    The System for Observing Play and Recreation in Communities (SOPARC) can obtain information on park users and their physical activity using momentary time sampling. We conducted a literature review of studies using the SOPARC tool to describe the observational methods of each study, and to extract public park use overall and by demographics and physical activity levels. We searched PubMed, Embase, and SPORTDiscus for full-length observational studies published in English in peer-reviewed journals through 2014. Twenty-four studies from 34 articles were included. The number of parks observed per study ranged from 3 to 50. Most studies observed parks during one season. The number of days parks were observed ranged from 1 to 16, with 16 studies observing 5 or more days. All studies included at least one weekday and all but two included at least one weekend day. Parks were observed from 1 to 14 times/day, with most studies observing at least 4 times/day. All studies included both morning and afternoon observations, with one exception. There was a wide range of park users (mean 1.0 to 152.6 people/park/observation period), with typically more males than females visiting parks and older adults less than other age groups. Park user physical activity levels varied greatly across studies, with youths generally more active than adults and younger children more active than adolescents. SOPARC was adapted to numerous settings and these review results can be used to improve future studies using the tool, demonstrate ways to compare park data, and inform park promotions and programming

    Cosmic ray short burst observed with the Global Muon Detector Network (GMDN) on June 22, 2015

    Get PDF
    We analyze the short cosmic ray intensity increase ("cosmic ray burst": CRB) on June 22, 2015 utilizing a global network of muon detectors and derive the global anisotropy of cosmic ray intensity and the density (i.e. the omnidirectional intensity) with 10-minute time resolution. We find that the CRB was caused by a local density maximum and an enhanced anisotropy of cosmic rays both of which appeared in association with Earth's crossing of the heliospheric current sheet (HCS). This enhanced anisotropy was normal to the HCS and consistent with a diamagnetic drift arising from the spatial gradient of cosmic ray density, which indicates that cosmic rays were drifting along the HCS from the north of Earth. We also find a significant anisotropy along the HCS, lasting a few hours after the HCS crossing, indicating that cosmic rays penetrated into the inner heliosphere along the HCS. Based on the latest geomagnetic field model, we quantitatively evaluate the reduction of the geomagnetic cut-off rigidity and the variation of the asymptotic viewing direction of cosmic rays due to a major geomagnetic storm which occurred during the CRB and conclude that the CRB is not caused by the geomagnetic storm, but by a rapid change in the cosmic ray anisotropy and density outside the magnetosphere.Comment: accepted for the publication in the Astrophysical Journa

    The problem of a metal impurity in an oxide: ab-initio study of electronic and structural properties of Cd in Rutile TiO2

    Get PDF
    In this work we undertake the problem of a transition metal impurity in an oxide. We present an ab-initio study of the relaxations introduced in TiO2 when a Cd impurity replaces substitutionally a Ti atom. Using the Full-Potential Linearized-Augmented-Plane-Wave method we obtain relaxed structures for different charge states of the impurity and computed the electric-field gradients (EFGs) at the Cd site. We find that EFGs, and also relaxations, are dependent on the charge state of the impurity. This dependence is very remarkable in the case of the EFG and is explained analyzing the electronic structure of the studied system. We predict fairly anisotropic relaxations for the nearest oxygen neighbors of the Cd impurity. The experimental confirmation of this prediction and a brief report of these calculations have recently been presented [P.R.L. 89, 55503 (2002)]. Our results for relaxations and EFGs are in clear contradiction with previous studies of this system that assumed isotropic relaxations and point out that no simple model is viable to describe relaxations and the EFG at Cd in TiO2 even approximately.Comment: 11 pages, 8 figures, Revtex 4, published in Physical Review

    Status of ANITA and ANITA-lite

    Full text link
    We describe a new experiment to search for neutrinos with energies above 3 x 10^18 eV based on the observation of short duration radio pulses that are emitted from neutrino-initiated cascades. The primary objective of the ANtarctic Impulse Transient Antenna (ANITA) mission is to measure the flux of Greisen-Zatsepin-Kuzmin (GZK) neutrinos and search for neutrinos from Active Galactic Nuclei (AGN). We present first results obtained from the successful launch of a 2-antenna prototype instrument (called ANITA-lite) that circled Antarctica for 18 days during the 03/04 Antarctic campaign and show preliminary results from attenuation length studies of electromagnetic waves at radio frequencies in Antarctic ice. The ANITA detector is funded by NASA, and the first flight is scheduled for December 2006.Comment: 9 pages, 8 figures, to be published in Proceedings of International School of Cosmic Ray Astrophysics, 14th Course: "Neutrinos and Explosive Events in the Universe", Erice, Italy, 2-13 July 200

    Parent’s Physical Activity Associated With Preschooler Activity in Underserved Populations

    Get PDF
    INTRODUCTION: In the U.S., children from low-income families are more likely to be obese. The impact of parent modeling of physical activity (PA) and sedentary behaviors in low-income American ethnic minorities is unclear, and studies examining objective measures of preschooler and parent PA are sparse. METHODS: This cross-sectional study examined 1,003 parent-child pairs who were of low income, largely Latino and African American, and living in one of two geographically disparate metropolitan areas in the U.S. Parents and children wore GT3X/GT3X+ accelerometers for an average of >12 hours/day (7:00am-9:00pm) for 1 week (September 2012 to May 2014). Analysis occurred in 2015-2016. RESULTS: About 75% of children were Latino and >10% were African American. Mean child age was 3.9 years. The majority of children (60%) were normal weight (BMI ≥50th and <85th percentiles), and more than a third were overweight/obese. Children's total PA was 6.03 hours/day, with 1.5 hours spent in moderate to vigorous PA (MVPA). Covariate-adjusted models showed a monotonic, positive association between parent and child minutes of sedentary behavior (β=0.10, 95% CI=0.06, 0.15) and light PA (β=0.06; 95% CI=0.03, 0.09). Child and parent MVPA were positively associated up to 40 minutes/day of parent MVPA, but an inverse association was observed when parental MVPA was beyond 40 minutes/day (p=0.002). CONCLUSIONS: Increasing parental PA and reducing sedentary behavior correlate with increased PA-related behaviors in children. However, more work is needed to understand the impact of high levels of parental MVPA on the MVPA levels of their children

    Wave vector dependence of the dynamics in supercooled metallic liquids

    Full text link
    We present a detailed investigation of the wave vector dependence of collective atomic motion in Au49Cu26.9Si16.3Ag5.5Pd2.3 and Pd42.5Cu27Ni9.5P21 supercooled liquids close to the glass transition temperature. Using x-ray photon correlation spectroscopy in a precedent uncovered spatial range of only few interatomic distances, we show that the microscopic structural relaxation process follows in phase the structure with a marked slowing down at the main average inter-particle distance. This behavior is accompanied by dramatic changes in the shape of the intermediate scattering functions which suggest the presence of large dynamical heterogeneities at length-scales corresponding to few particle diameters. A ballistic-like mechanism of particle motion seems to govern the structural relaxation of the two systems in the highly viscous phase, likely associated to hopping of caged particles in agreement with theoretical studies

    AVERAGE SPATIAL DISTRIBUTION OF COSMIC RAYS BEHIND THE INTERPLANETARY SHOCK-GLOBAL MUON DETECTOR NETWORK OBSERVATIONS

    Get PDF
    We analyze the galactic cosmic ray (GCR) density and its spatial gradient in Forbush Decreases (FDs) observed with the Global Muon Detector Network (GMDN) and neutron monitors (NMs). By superposing the GCR density and density gradient observed in FDs following 45 interplanetary shocks (IP-shocks), each associated with an identified eruption on the Sun, we infer the average spatial distribution of GCRs behind IP-shocks. We find two distinct modulations of GCR density in FDs, one in the magnetic sheath and the other in the coronal mass ejection (CME) behind the sheath. The density modulation in the sheath is dominant in the western flank of the shock, while the modulation in the CME ejecta stands out in the eastern flank. This east-west asymmetry is more prominent in GMDN data responding to similar to 60 GV GCRs than in NM data responding to similar to 10 GV GCRs, because of the softer rigidity spectrum of the modulation in the CME ejecta than in the sheath. The geocentric solar ecliptic-y component of the density gradient, G(y), shows a negative (positive) enhancement in FDs caused by the eastern (western) eruptions, while G(z) shows a negative (positive) enhancement in FDs caused by the northern (southern) eruptions. This implies that the GCR density minimum is located behind the central flank of IP-shocks and propagating radially outward from the location of the solar eruption. We also confirmed that the average Gz changes its sign above and below the heliospheric current sheet, in accord with the prediction of the drift model for the large-scale GCR transport in the heliosphere.ArticleASTROPHYSICAL JOURNAL. 825(2):100 (2016)journal articl

    Sorghum Genetic Enhancement: Research Process, Dissemination and Impacts

    Get PDF
    This volume covers 32 years of sorghum research across ICRISAT in partnership wi th NARS in Asia, Africa and Latin America and gives insights on the many facets of the research process, dissemination and impacts. The volume was completed through close collaboration among biological, natural and social scientists. The chapters document the f low of ICRISAT sorghum germplasm across regions and the genetic enhancement research process in partnership wi t h NARS. It elaborates on ICRISAT's contribution to NARS breeding programs through capacity building and the supply of useful germplasm, breeding materials, hybrid parents and cultivars. It assesses the impacts of ICRISAT-NARS partnerships in genetic enhancement research on sorghum. The contents include an introduction to the crop, trends in global sorghum production; conservation, utilization and distribution of sorghum germplasm; research-for-development targets; research processes and strategies in Asia, Africa and Latin America, its outputs and contributions to public and private sector institutions; applications of new tools, regional breeding and market-oriented needs of sorghum. Wi th the ultimate aim of increasing sorghum production worldwide, ICRISAT has readily made available its germplasm to NARS of developing and developed countries. Since NARS evaluation and selection of materials has led to the incorporation of ICRISAT germplasm into varieties released and grown in farmers' field, this book assessed the value of the germplasm to NARS and the seed sector. A systematic documentation and analysis of the use of ICRISAT germplasm is undertaken for understanding the role of its germplasm products in varietal development worldwide. Mechanisms to increase the efficiency of genetic enhancement research are explored through a better understanding of past activities and their impact on the development of new cultivars by ICRISAT and its partners. This facilitates exploitation of the wor ld germplasm base and helps identify means of achieving greater utility. Several chapters dealt wi th research partnerships and technology exchange, adoption of improved cultivars and lessons learned f rom adoption studies as wel l as critical factors influencing the uptake process. Important dimensions of the impacts of sorghum research are highlighted. Research benefits were measured in terms of increase in yields, reduction in per uni t cost of production, increase in stability in sorghum yield and improved food security. The nature, extent and determinants of sorghum research spillover effects across continents and agro-ecological zones were also examined and quantified. The concluding chapter presents future directions for partnership and a research strategy for sorghum research-for-development, suggesting new and innovative partnerships among all players (ICRISAT, NARS, public- and private-seed sectors and NGOs ) . This book serves as a valuable resource and wi l l be of significant interest to those working in plant breeding, crop science and agricultural economics

    Comparison of a nurse initiated insulin infusion protocol for intensive insulin therapy between adult surgical trauma, medical and coronary care intensive care patients

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>Sustained hyperglycemia is a known risk factor for adverse outcomes in critically ill patients. The specific aim was to determine if a nurse initiated insulin infusion protocol (IIP) was effective in maintaining blood glucose values (BG) within a target goal of 100–150 mg/dL across different intensive care units (ICUs) and to describe glycemic control during the 48 hours after protocol discontinuation.</p> <p>Methods</p> <p>A descriptive, retrospective review of 366 patients having 28,192 blood glucose values in three intensive care units, Surgical Trauma Intensive Care Unit (STICU), Medical (MICU) and Coronary Care Unit (CCU) in a quaternary care hospital was conducted. Patients were > 15 years of age, admitted to STICU (n = 162), MICU (n = 110) or CCU (n = 94) over 8 months; October 2003-June 2004 and who had an initial blood glucose level > 150 mg/dL. We summarized the effectiveness and safety of a nurse initiated IIP, and compared these endpoints among STICU, MICU and CCU patients.</p> <p>Results</p> <p>The median blood glucose values (mg/dL) at initiation of insulin infusion protocol were lower in STICU (188; IQR, 162–217) than in MICU, (201; IQR, 170–268) and CCU (227; IQR, 178–313); <it>p </it>< 0.0001. Mean time to achieving a target glucose level (100–150 mg/dL) was similar between the three units: 4.6 hours in STICU, 4.7 hours in MICU and 4.9 hours in CCU (<it>p </it>= 0.27). Hypoglycemia (BG < 60 mg/dL) occurred in 7% of STICU, 5% of MICU, and 5% of CCU patients (<it>p </it>= 0.85). Protocol violations were uncommon in all three ICUs. Mean blood glucose 48 hours following IIP discontinuation was significantly different for each population: 142 mg/dL in STICU, 167 mg/dL in MICU, and 160 mg/dL in CCU (<it>p </it>< 0.0001).</p> <p>Conclusion</p> <p>The safety and effectiveness of nurse initiated IIP was similar across different ICUs in our hospital. Marked variability in glucose control after the protocol discontinuation suggests the need for further research regarding glucose control in patients transitioning out of the ICU.</p
    • …
    corecore