937 research outputs found

    Envirocare of Utah: Expanding Waste Acceptance Criteria to Provide Low-Level and Mixed Waste Disposal Options.

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    Envirocare of Utah operates a low-level radioactive waste disposal facility 80 miles west of Salt Lake City in Clive, Utah. Accepted waste types includes NORM, 11e2 byproduct material, Class A low-level waste, and mixed waste. Since 1988, Envirocare has offered disposal options for environmental restoration waste for both government and commercial remediation projects. Annual waste receipts exceed 12 million cubic feet. The waste acceptance criteria (WAC) for the Envirocare facility have significantly expanded to accommodate the changing needs of restoration projects and waste generators since its inception, including acceptable physical waste forms, radiological acceptance criteria, RCRA requirements and treatment capabilities, PCB acceptance, and liquids acceptance. Additionally, there are many packaging, transportation, and waste management options for waste streams acceptable at Envirocare. Many subcontracting vehicles are also available to waste generators for both government and commercial activities

    Heavy Residue Formation in 20 MeV/nucleon 197Au + 90Zr collisions

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    The yields and velocity distributions of heavy residues and fission fragments from the reaction of 20 MeV/nucleon 197Au + 90Zr have been measured using the MSU A1200 fragment separator. A bimodal distribution of residues is observed, with one group, resulting from peripheral collisions, having fragment mass numbers A=160-200, while the other group, resulting from ``hard'' collisions, has A=120-160. This latter group of residues can be distinguished from fission fragments by their lower velocities. A model combining deep-inelastic transfer and incomplete fusion for the primary interaction stage and a statistical evaporation code for the deexcitation stage has been used to describe the properties of the product distributions.Comment: 19 pages, 6 figures, preprint submitted to Nucl. Phys.

    Neutron-rich rare isotope production from projectile fission of heavy beams in the energy range of 20 MeV/nucleon

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    We investigate the possibilities of producing neutron-rich nuclides in projectile fission of heavy beams in the energy range of 20 MeV/nucleon expected from low-energy facilities. We report our efforts to theoretically describe the reaction mechanism of projectile fission following a multinucleon transfer collision at this energy range. Our calculations are mainly based on a two-step approach: the dynamical stage of the collision is described with either the phenomenological Deep-Inelastic Transfer model (DIT), or with the microscopic Constrained Molecular Dynamics model (CoMD). The deexcitation/fission of the hot heavy projectile fragments is performed with the Statistical Mul- tifragmentation Model (SMM). We compared our model calculations with our previous experimental projectile-fission data of 238U (20 MeV/nucleon)+208Pb and 197Au (20 MeV/nucleon)+197Au and found an overall reasonable agreement. Our study suggests that projectile fission following periph- eral heavy-ion collisions at this energy range offers an effective route to access very neutron-rich rare isotopes toward and beyond the astrophysical r-process path

    Performance of statistical models to predict mental health and substance abuse cost

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    BACKGROUND: Providers use risk-adjustment systems to help manage healthcare costs. Typically, ordinary least squares (OLS) models on either untransformed or log-transformed cost are used. We examine the predictive ability of several statistical models, demonstrate how model choice depends on the goal for the predictive model, and examine whether building models on samples of the data affects model choice. METHODS: Our sample consisted of 525,620 Veterans Health Administration patients with mental health (MH) or substance abuse (SA) diagnoses who incurred costs during fiscal year 1999. We tested two models on a transformation of cost: a Log Normal model and a Square-root Normal model, and three generalized linear models on untransformed cost, defined by distributional assumption and link function: Normal with identity link (OLS); Gamma with log link; and Gamma with square-root link. Risk-adjusters included age, sex, and 12 MH/SA categories. To determine the best model among the entire dataset, predictive ability was evaluated using root mean square error (RMSE), mean absolute prediction error (MAPE), and predictive ratios of predicted to observed cost (PR) among deciles of predicted cost, by comparing point estimates and 95% bias-corrected bootstrap confidence intervals. To study the effect of analyzing a random sample of the population on model choice, we re-computed these statistics using random samples beginning with 5,000 patients and ending with the entire sample. RESULTS: The Square-root Normal model had the lowest estimates of the RMSE and MAPE, with bootstrap confidence intervals that were always lower than those for the other models. The Gamma with square-root link was best as measured by the PRs. The choice of best model could vary if smaller samples were used and the Gamma with square-root link model had convergence problems with small samples. CONCLUSION: Models with square-root transformation or link fit the data best. This function (whether used as transformation or as a link) seems to help deal with the high comorbidity of this population by introducing a form of interaction. The Gamma distribution helps with the long tail of the distribution. However, the Normal distribution is suitable if the correct transformation of the outcome is used

    The epidemiology of traumatic brain injuries sustained by children under 10 years of age presenting to a tertiary hospital in Soweto, South Africa

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    Background. Traumatic brain injury (TBI) in the paediatric population is a significant contributor to death and disability worldwide. In sub-Saharan Africa, death and disability from TBI are still superseded by infectious disease. Mechanisms of injury differ by region and socioeconomics, but in general, falls, road traffic collisions (RTCs), being ‘struck by/against objects’ and non-accidental injuries (NAIs) are responsible for most cases.Objectives. To: (i) quantify the burden of TBI in terms of demographics, causes and severity; (ii) explore resource utilisation regarding length of stay, computed tomography (CT) brain scan use and multidisciplinary participation; (iii) interrogate possible temporal patterns of injury; and (iv) thus identify potential targets for community-based prevention strategies.Methods. In a 5-year retrospective review of all children aged <10 years admitted with TBI between September 2013 and August 2018, demographics, date of injury, mechanism of injury, severity of TBI based on the Glasgow Coma Scale, and requirement for a CT brain scan were collected for each patient. Outcomes were reported as discharge, transfer or death. Outcomes for children sustaining isolated TBI were compared with those for children sustaining TBI with polytrauma.Results. A total of 2 153 patients were included, with a mean (standard deviation) age of 4.6 (2.7) years and a male/female ratio of 1.7:1. RTCs were the most frequent cause of injury at 59% (80% of these were pedestrian-vehicle collisions), followed by falls at 24%. Mild TBIs accounted for 87% of admissions, moderate injuries for 6%, and severe injuries for 7%. Polytrauma was associated with increased severity of TBI. The cohort had a 2.3% mortality. NAIs accounted for 6% of injuries and carried a 4% mortality. The median (interquartile range) duration of hospitalisation was 1 (1 - 3) days, ranging from <24 hours to 132 days. CT scans were performed on 43% of admitted patients, and 48% of patients had consultations with another medical or allied medical discipline. Injuries were more frequent during the summer months and over weekends. Infants aged <1 year were identified as a group particularly vulnerable to injury, specifically NAI.Conclusions. Paediatric TBI was demonstrated to be a resource-intensive public health concern. From the results, we identified potential primary prevention targets that could perhaps be incorporated into broader community-based intervention programmes. We also identified a need to study long-term consequences of mild TBI further in our paediatric population

    The Political Participation of First Year Social Work Students: Does Practice Specialization Matter?

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    This study identifies the types of political participation engaged in by MSW students (n=214). A self-report survey administered to MSW students at a Northeastern university indicates limited political involvement. MSW students participate in political activities not requiring significant time, energy, or resources. Furthermore, on the scale and its two subscales, micro-oriented students had less political participation than macro-oriented students. This study suggests firstyear social work students may lack the tools to engage in the political process effectively. Schools of social work should include political participation education in both micro and macro foundation courses and field placement

    Structure effects in the region of superheavy elements via the α\alpha-decay chain of 293^{293}118

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    The α\alpha-decay chain of 293^{293}118, first proposed in the Berkeley cold fusion experiment 208^{208}Pb(86^{86}Kr,1n) and now retracted, is calculated by using the preformed cluster model (PCM) of one of us (RKG). Also, the possible branchings of α\alpha-particles to heavier cluster decays of all the parents in this chain are calculated for the first time. The calculated Q-values, penetrabilities and preformation factors for α\alpha-decays suggest that the 285^{285}114 nucleus with Z=114, N=171 is a magic nucleus, either due to the magicity of Z=114, or of N=172 or of both. The N=172 is proposed to be a magic number in certain relativistic mean-field calculations, but with Z=120. The calculated cluster decays point to new interesting possibilities of 14^{14}C decay of the 281^{281}112 parent, giving rise to a (reasonably) deformed Z=106, N=161, 267^{267}106 daughter (N=162 being now established as the deformed magic shell) or to a doubly magic 48^{48}Ca cluster emitted from any of the parent nucleus in the α\alpha-decay chain. Apparently, these are exciting new directions for future experiments

    Search for the Production of Element 112 in the 48Ca + 238U Reaction

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    We have searched for the production of element 112 in the reaction of 231 MeV 48Ca with 238U. We have not observed any events with a "one event" upper limit cross section of 1.6 pb for EVR-fission events and 1.8 pb for EVR-alpha events.Comment: 6 pages, 3 figures, submitted to Phys. Rev.
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