317 research outputs found

    Proton Spectrum at the Jupiter Laser Facility of LLNL

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    This paper looks at tungsten samples irradiated by beams of protons, gammas, electrons and positrons at the Jupiter Laser Facility of Lawrence Livermore National Laboratory (LLNL). The resulting unstable nuclei created are identified using their gamma spectra. These spectra were taken, usually within an hour of irradiation, for periods up to 48 hrs. In several cases there are two isotopes, one of Rhenium and the other of Tantalum, that emit the same gamma lines. These pairs often involve a long-lived and a short-lived candidate. Spectra were taken 80 days after initial exposure and the long-lived candidates are ruled out

    Comparison of Inappropriate Shocks and Other Health Outcomes Between Single- and Dual-Chamber Implantable Cardioverter-Defibrillators for Primary Prevention of Sudden Cardiac Death: Results From the Cardiovascular Research Network Longitudinal Study of Implantable Cardioverter-Defibrillators

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    BACKGROUND: In US clinical practice, many patients who undergo placement of an implantable cardioverter-defibrillator (ICD) for primary prevention of sudden cardiac death receive dual-chamber devices. The superiority of dual-chamber over single-chamber devices in reducing the risk of inappropriate ICD shocks in clinical practice has not been established. The objective of this study was to compare risk of adverse outcomes, including inappropriate shocks, between single- and dual-chamber ICDs for primary prevention. METHODS AND RESULTS: We identified patients receiving a single- or dual-chamber ICD for primary prevention who did not have an indication for pacing from 15 hospitals within 7 integrated health delivery systems in the Longitudinal Study of Implantable Cardioverter-Defibrillators from 2006 to 2009. The primary outcome was time to first inappropriate shock. ICD shocks were adjudicated for appropriateness. Other outcomes included all-cause hospitalization, heart failure hospitalization, and death. Patient, clinician, and hospital-level factors were accounted for using propensity score weighting methods. Among 1042 patients without pacing indications, 54.0% (n=563) received a single-chamber device and 46.0% (n=479) received a dual-chamber device. In a propensity-weighted analysis, device type was not significantly associated with inappropriate shock (hazard ratio, 0.91; 95% confidence interval, 0.59-1.38 [P=0.65]), all-cause hospitalization (hazard ratio, 1.03; 95% confidence interval, 0.87-1.21 [P=0.76]), heart failure hospitalization (hazard ratio, 0.93; 95% confidence interval, 0.72-1.21 [P=0.59]), or death (hazard ratio, 1.19; 95% confidence interval, 0.93-1.53 [P=0.17]). CONCLUSIONS: Among patients who received an ICD for primary prevention without indications for pacing, dual-chamber devices were not associated with lower risk of inappropriate shock or differences in hospitalization or death compared with single-chamber devices. This study does not justify the use of dual-chamber devices to minimize inappropriate shocks

    13kW Advanced Electric Propulsion Flight System Development and Qualification

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    The next phase of robotic and human deep space exploration missions requires high performance, high power solar electric propulsion systems for large-scale science missions and cargo transportation. Aerojet Rocketdyne's Advanced Electric Propulsion System (AEPS) program is completing development and qualification of a 13kW flight EP system to support NASA exploration. The first use of the AEPS is planned for the NASA Power & Propulsion Element, which is the first element of NASA's cis-lunar Gateway. The flight AEPS system includes a magnetically shielded long-life Hall thruster, power processing unit (PPU), and xenon flow controller (XFC). The Hall thruster, originally developed and demonstrated by NASA's Glenn Research Center and the Jet Propulsion Laboratory, operates at input powers up to 13.3kW while providing a specific impulse over 2600s at an input voltage of 600V. The power processor is designed to accommodate an input voltage range of 95 to 140V, consistent with operation beyond the orbit of Mars. The integrated system is continuously throttleable between 3 and 13.3kW. The program has completed testing of the Technology Development Units and is progressing into the Engineering Development Unit test phase and the final design phase to Critical Design Review (CDR). This paper will present the high power AEPS system capabilities, overall program and design status and the latest test results for the 13kW flight system development as well as the plans for the development and qualification effort of the EP string

    Potential net primary productivity in South America: application of a global model

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    We use a mechanistically based ecosystem simulation model to describe and analyze the spatial and temporal patterns of terrestrial net primary productivity (NPP) in South America. The Terrestrial Ecosystem Model (TEM) is designed to predict major carbon and nitrogen fluxes and pool sizes in terrestrial ecosystems at continental to global scales. Information from intensively studies field sites is used in combination with continental—scale information on climate, soils, and vegetation to estimate NPP in each of 5888 non—wetland, 0.5° latitude °0.5° longitude grid cells in South America, at monthly time steps. Preliminary analyses are presented for the scenario of natural vegetation throughout the continent, as a prelude to evaluating human impacts on terrestrial NPP. The potential annual NPP of South America is estimated to be 12.5 Pg/yr of carbon (26.3 Pg/yr of organic matter) in a non—wetland area of 17.0 ° 106 km2. More than 50% of this production occurs in the tropical and subtropical evergreen forest region. Six independent model runs, each based on an independently derived set of model parameters, generated mean annual NPP estimates for the tropical evergreen forest region ranging from 900 to 1510 g°m—2°yr—1 of carbon, with an overall mean of 1170 g°m—2°yr—1. Coefficients of variation in estimated annual NPP averaged 20% for any specific location in the evergreen forests, which is probably within the confidence limits of extant NPP measurements. Predicted rates of mean annual NPP in other types of vegetation ranged from 95 g°m—2°yr—1 in arid shrublands to 930 g°m@?yr—1 in savannas, and were within the ranges measured in empirical studies. The spatial distribution of predicted NPP was directly compared with estimates made using the Miami mode of Lieth (1975). Overall, TEM predictions were °10% lower than those of the Miami model, but the two models agreed closely on the spatial patterns of NPP in south America. Unlike previous models, however, TEM estimates NPP monthly, allowing for the evaluation of seasonal phenomena. This is an important step toward integration of ecosystem models with remotely sensed information, global climate models, and atmospheric transport models, all of which are evaluated at comparable spatial and temporal scales. Seasonal patterns of NPP in South America are correlated with moisture availability in most vegetation types, but are strongly influenced by seasonal differences in cloudiness in the tropical evergreen forests. On an annual basis, moisture availability was the factor that was correlated most strongly with annual NPP in South America, but differences were again observed among vegetation types. These results allow for the investigation and analysis of climatic controls over NPP at continental scales, within and among vegetation types, and within years. Further model validation is needed. Nevertheless, the ability to investigate NPP—environment interactions with a high spatial and temporal resolution at continental scales should prove useful if not essential for rigorous analysis of the potential effects of global climate changes on terrestrial ecosystems

    A Comparison of Two Quail Abundance Indices and Their Relationship to Quail Harvest in Texas

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    Surveys are used to monitor status and trends of animal populations. However, different surveys may give conflicting results for the same species and population being surveyed. Therefore, we compared results of the North American Breeding Bird Survey (BBS) and Texas Parks and Wildlife (TPW) roadside counts for scaled quail (Callipepla squamata) and northern bobwhite (Colinus virginianus) in Texas. Surveys were compared on both an ecoregion and statewide basis. The BBS and TPW surveys gave similar trends for bobwhites and scaled quail for 5 of 8, and 3 of 5 ecoregions, respectively. Survey trends differed at the statewide scale for both species. We compared estimated statewide harvest as an independent index of quail population status in Texas with results from both surveys. The TPW roadside survey was more closely related to estimated statewide harvest for northern bobwhites (R2 = 0.86, P \u3c= 0.001) and scaled quail (R2 = 0.75, P = 0.0001) than the BBS survey (R2 = 0.60, P = 0.001; and R2 = 0.35, P = \u3c0.0001, respectively). Survey methods, sampling frameworks, and issues of scale are important variables to consider when interpreting survey results. The BBS provides useful data on quail populations at a multi-state or national scale. However, most state wildlife agencies require surveys that provide information at finer spatial scales

    De novo once-monthly darbepoetin α treatment for the anemia of chronic kidney disease using a computerized algorithmic approach

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    Background: Anemia of chronic kidney disease (CKD) has been traditionally treated by erythropoiesis-stimulating agents (ESAs) and/or iron following manual determination of dose. We hypothesized that once-monthly (QM) algorithmically dosed darbepoetin α (DA) and iron administration would successfully treat anemia of CKD in ESA-naive CKD subjects. Methods: QM DA and iron doses were determined via a computerized program targeting a hemoglobin (Hb) of 10.5 - 12.5 g/dl in anemic, ESA-naive, CKD Stages 3 - 5 subjects. Six consecutive QM doses were administered. Hb, ferritin, and transferrin saturation were recorded. Data are presented as means ± standard deviation. Results: Anemia was identified in 133 subjects, with a mean follow-up of 188 days. DA doses and Hb were significantly greater at Months 3 and 6 compared to baseline (p \u3c 0.05); DA doses were 109 ± 68 μg and 118 ± 91, respectively, at Months 3 and 6. Hemoglobin levels were correspondingly 11.3 ± 1.1 g/dl and 11.3 ± 1.0. 78% of patients achieved the target Hb by 6 months of therapy. The elevation of Hb was greater in non-proteinuric than proteinuric subjects at 6 months of treatment (11.6 ± 0.8 g/dl vs. 11.0 ± 1.1; p \u3c 0.05), despite lower DA dose (96 ± 76 μg vs. 139 ± 98; p \u3c 0.05). Conclusion: Successful treatment of the anemia of CKD by QM DA based upon a computerized dosing program was achieved by 6 months in 78% of ESA-naïve, CKD subjects. © 2011 Dustri-Verlag Dr. K. Feistle

    Factors Associated With Ordering Laboratory Monitoring Of High-Risk Medications

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    Background Knowledge about factors associated with provider ordering of appropriate testing is limited. Objective To determine physician factors correlated with ordering of recommended laboratory monitoring tests for high-risk medications, accounting for patient characteristics. Methods Analysis of the administrative claims and electronic medical records of patients prescribed a high-risk medication requiring laboratory monitoring in a large multispecialty group practice between January 1, 2008 and December 31, 2008. The outcome is a physician order for each recommended laboratory test for each prescribed medication. Key predictor variables include physician characteristics, including age, gender, specialty training, years since completing training, and prescribing volume. We used multivariable logistic regression to identify the independent association of physician and patient characteristics with ordering of laboratory tests to monitor medications after adjustment for potential confounders, taking into account clustering of drugs within patients and patients within providers. Results Physician orders for laboratory testing varied across drug-test pairs and ranged from 9% (Primidone–Phenobarbital level) to 97% (Azathioprine–CBC) with 50% of drug-test pairs in the 85-91% ordered range. Failure to order a test was associated with lower provider prescribing volume for study drugs and whether the physician was a specialist (primary care providers were more likely to order tests than specialists). Patients with lower patient comorbidity burden and younger patients were less likely to have appropriate tests ordered. Drug-test combinations with black box warnings were more likely to have tests ordered. Conclusions Interventions targeting providers should be addressed at those subgroups with the greatest potential for improvement: providers with lower frequencies of prescribing high-risk medications, and healthier and younger patients. Drug-test combinations with black box warnings have higher ordering rates, but many medications without such warnings also have evidence of harm, thus efforts to improve testing are necessary for all medications shown to be high-risk

    Proceedings International Sorghum and Millet CRSP Conference

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    On behalf of the INTSORMIL Board of Directors, Principal Investigators and the Management Entity Office, it gives me great pleasure this moming to welcome you to this opening session of the 1991 INTSORMIL International SorghumIMlllet CRSP Conference. INTSORMIL initiated the Biennial CRSP conference series in 1983. Attendance has grown with each meeting. Today we have 199 persons registered from 12 States in the U.S. and 27 different countries. There are representatives from three International Agricultural Research Centers (lCRISAT, IFPRI, and ICRISAT), four private seed companies and the U.S. National Grain Sorghum Producers Association (NGSPA). I look around this audience and see new faces and old friends. I see senior sorghum and millet scientists from Africa and ICRISAT. I see senior NARS administrators who value the collaborative research relationship between INTSORM IL and their staff. I see graduate students from around the world. I see INTSORMIL graduates who have accepted major administrative responsibilities in the NARS of their home countries. I see the cream of the crop of developed and developing world sorghum and millet science. We have come to share our ideas and concepts about how to make further contributions to resolution of hunger and poverty In those developing countries where sorghum and millet are major food grain crops

    Insights and issues with simulating terrestrial DOC loading of Arctic river networks

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    Author Posting. © Ecological Society of America, 2013. This article is posted here by permission of Ecological Society of America for personal use, not for redistribution. The definitive version was published in Ecological Applications 23 (2013): 1817-1836, doi:10.1890/11-1050.1.Terrestrial carbon dynamics influence the contribution of dissolved organic carbon (DOC) to river networks in addition to hydrology. In this study, we use a biogeochemical process model to simulate the lateral transfer of DOC from land to the Arctic Ocean via riverine transport. We estimate that, over the 20th century, the pan-Arctic watershed has contributed, on average, 32 Tg C/yr of DOC to river networks emptying into the Arctic Ocean with most of the DOC coming from the extensive area of boreal deciduous needle-leaved forests and forested wetlands in Eurasian watersheds. We also estimate that the rate of terrestrial DOC loading has been increasing by 0.037 Tg C/yr2 over the 20th century primarily as a result of climate-induced increases in water yield. These increases have been offset by decreases in terrestrial DOC loading caused by wildfires. Other environmental factors (CO2 fertilization, ozone pollution, atmospheric nitrogen deposition, timber harvest, agriculture) are estimated to have relatively small effects on terrestrial DOC loading to Arctic rivers. The effects of the various environmental factors on terrestrial carbon dynamics have both offset and enhanced concurrent effects on hydrology to influence terrestrial DOC loading and may be changing the relative importance of terrestrial carbon dynamics on this carbon flux. Improvements in simulating terrestrial DOC loading to pan-Arctic rivers in the future will require better information on the production and consumption of DOC within the soil profile, the transfer of DOC from land to headwater streams, the spatial distribution of precipitation and its temporal trends, carbon dynamics of larch-dominated ecosystems in eastern Siberia, and the role of industrial organic effluents on carbon budgets of rivers in western Russia.This study was supported, in part, by the U.S. National Science Foundation under grants ARC-0531047, ARC-0531082, ARC-0531119, ARC-0554811, and ARC- 0652838; the U.S. Environmental Protection Agency under grant R833261; the U.S. Department of Energy under grant DE-FG02-08ER64597; and the U.S. National Aeronautics and Space Administration under grant NNX09A126G

    Physical Oceanography of the Southwest Atlantic Ocean

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    First Paragraph: From its littoral margin to the open ocean, the western South Atlantic (Fig. 1) is marked at all depths by circulation patterns and exchange processes that are centrally important to the regional marine resources and local economies, and to the global flux of heat and dissolved substances. Among other important characteristics, the Southwest Atlantic (SWA) is characterized by the presence of the Brazil Current (BC), a warm western boundary current that, while weaker than the Gulf Stream in terms of mass transport, is energetically comparable to its North Atlantic counterpart, particularly in the region of confluence with the northward-flowing Malvinas Current (MC) at approximately 38°S. Because of the wide range of issues needed to be understood in terms of the physical oceanography, this oceanic region has been addressed by several important scientific programs, a few of which are listed in Table 1 and indicated on Fig. 2. Results from these and other programs are summarized here and recommendations for future efforts are offered
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