904 research outputs found

    Interaction of He and He-V clusters with self-interstitials and dislocations defects in bcc Fe

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    The understanding of helium effects in synergy with radiation damage is crucial for the development of structural steels for fusion applications. Recent investigations in ultra-pure iron, taken as a basic model, have shown a drastic impact of dual beam (helium and iron) exposure on the accumulation of radiation-induced dislocation loops in terms of strong bias towards a(0)/2 loops, while a(0) loops are mostly observed upon iron ion beam. In this work we perform a series of atomistic studies to rationalize possible mechanisms through which He could affect the evolution of microstructure and bias the population of a(0)/2 loops. It is shown that He atoms are dragged by gliding a(0)/2 loops. This strongly suppresses loop diffusivity and in turn it prohibits the mutual interaction of a(0)/2 loops, being prerequisite of the formation of a(0) loops, as well as it reduces the disappearance of a(0)/2 loops at sinks. A scenario for the microstructural evolution in the single-and dual-beam conditions is discussed. (C) 2014 Elsevier B. V. All rights reserved.Peer ReviewedPostprint (author's final draft

    Lineal gravity from planar gravity

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    We show how to obtain the two-dimensional black hole action by dimensional reduction of the three-dimensional Einstein action with a non-zero cosmological constant. Starting from the Chern-Simons formulation of 2+1 gravity, we obtain the 1+1 dimensional gauge formulation given by Verlinde. Remarkably, the proposed reduction shares the relevant features of the formulation of Cangemi and Jackiw, without the need for a central charge in the algebra. We show how the Lagrange multipliersin these formulations appear naturally as the remnants of the three dimensional connection associated to symmetries that have been lostin the dimensional reduction. The proposed dimensional reduction involves a shift in the three dimensional connection whose effect is to make the length of the extra dimension infinite.Comment: 13 pages, plain Te

    Five-year diagnostic stability among adolescents in an inpatient psychiatric unit

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    Introduction: In childhood, diagnoses made at the first admission to a psychiatric unit are frequently unstable and temporary. In this study, we examined the stability of DSM-IV-TR disorders and groups of disorders among adolescents followed-up for 5 years after hospitalization. Method: All inpatients admitted for the first time between 2007 and 2008 were included and contacted after 5 years for re-evaluation. The final sample comprised 72 patients. At admission, diagnoses were based on the DSM-IV-TR criteria, Fourth Edition. At five years, diagnoses were made using structured clinical interviews for DSM-IV axis I Disorders and for axis II (SCID-I and SCID-II) as well as the Personality Diagnostic Questionnaire, Fourth Edition (PDQ-4). We also evaluated and collected information on the global assessment of functioning using the World Health Organization Quality of Life-BREF (WHOQOL-BREF) instrument. Depending on the distribution of variables, we used the chi-squared and Fisher exact tests or the Student t and McNemar tests for statistical analyses. Results: The most stable diagnoses were schizophrenia spectrum disorders, bipolar disorder, generalized anxiety disorder, obsessive-compulsive disorder, attention deficit hyperactivity disorder, Tourette syndrome, and pervasive developmental disorder. The most unstable diagnoses were disruptive disorders. Participants were satisfied with their quality of life and the global outcomes of the sample were positive. Conclusion: Major psychiatric disorders, including mood and schizophrenia spectrum disorders, were significantly more stable than other diagnoses and tended to continue into adulthood. In the case of study participants, suffering a mental disorder during adolescence did not appear to affect global functioning outcomes

    Synthesis and gas separation properties of poly(ionic liquid)-ionic liquid composite membranes containing a copper salt

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    Composite poly(ionic liquid)-ionic liquid membranes containing copper (I) chloride (CuCl) have been successfully fabricated via photopolymerization of an IL monomer, 1-vinyl-3-butylimidazolium bistriflimide ([C4vim][Tf2N]), in the presence of CuCl and a non-polymerizable IL, 1-butyl-3-methylimidazolium chloride ([C4mim][Cl]), forming the chlorocuprate anion ([CuCl2]-) in situ. The influence of the metal salt content on the gas separation performance of the composite membranes was assessed. Results showed that increasing the content of non-polymerizable IL enhanced the permeabilities of CO2, H2, N2 and CO relative to those obtained in the pristine poly([C4vim][Tf2N]); whereas the addition of CuCl induced a general reduction of gas diffusivity. On the whole, an enhancement of both gas permeability and ideal gas pair selectivity were observed for CO2/N2 and H2/N2 separations in the Cu-containing composite membranes with respect to the neat poly([C4vim][Tf2N]).Financial support from the Spanish Ministry of Economy and Competitiveness (MINECO) under projects CTQ2012-31639 at the Universidad de Cantabria is gratefully acknowledged. Additional support from the American Chemical Society – Petroleum Research Fund (ACS-PRF 52190-DNI9) is acknowledged

    Volatile compounds in the thermoplastic extrusion of bovine rumen

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    The volatile compounds of raw and extruded bovine rumen, extracted by dynamic headspace, were separated by gas chromatography and analyzed by GC-MS. Raw and extruded materials presented thirty-two volatile compounds. The following compounds were identified in raw bovine rumen: heptane, 1-heptene, 4-methyl-2-pentanone, toluene, hexanal, ethyl butyrate, o-xylene, m-xylene, p-xylene, heptanal, limonene, nonanal, dodecane, tridecane, tetradecane, pentadecane, hexadecane, heptadecane and octadecane. The following compounds were identified in the extruded material: 1-heptene, 2,4-dimethylhexane, toluene, limonene, undecane, tetradecane, pentadecane, hexadecane, heptadecane, octadecane and nonadecane. Mass spectra of some unidentified compounds indicated the presence of hydrocarbons with branched chains or cyclic structure.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

    Agriculture, Food and Natural Resources Handbook 2011

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    The use of lead (Pb) ammunition in the form of shot pellets has been identified as a Pb exposure risk in wildlife and their human consumers. We explore the hypothesis that Pb shot ban enforcement reduces the risk of avian Pb poisoning as well as Pb exposure in game meat consumers. We assessed compliance with a partial ban on Pb shot commencing in 2003 by examination of 937 waterbirds harvested by hunters between 2007 and 2012 in the Ebro delta (Spain). Prevalence of Pb shot ingestion was determined, as were Pb concentrations in liver and muscle tissue to evaluate the potential for Pb exposure in game meat consumers. Hunted birds with only embedded Pb shot (no steel) declined from 26.9% in 2007–08 to < 2% over the following three hunting seasons after ban reinforcement. Pb shot ingestion in mallards decreased from a pre-ban value of 30.2% to 15.5% in the post-ban period. Liver Pb levels were predominantly defined by the presence of ingested shot, whereas muscle levels were defined by the presence of both ingested and embedded shot. Only 2.5% of mallard muscle tissue had Pb levels above European Union regulations for meat (0.1 μg/g wet weight) in the 2008–09 season, when Pb shot ingestion prevalence was also at a minimum (5.1%). Effective restrictions in Pb ammunition use have a dual benefit since this reduces Pb exposure for game meat consumers due to embedded ammunition as well as reducing Pb poisoning in waterbirds

    Understanding Parents\u27 Views toward the Newly Enacted HPV Vaccine School Entry Policy in Puerto Rico: A Qualitative Study

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    BACKGROUND: The Human papillomavirus vaccine (HPV) is an essential tool for the prevention of HPV-related cancers. In Puerto Rico, the Secretary of Health established a school entry requirement of at least one dose of HPV vaccination in girls and boys aged 11 and 12 years, taking effect in August 2018. Our study aimed to examine parents\u27 and guardians\u27 views of unvaccinated children about the process of implementation of the new HPV vaccination school entry policy in Puerto Rico and identify potential barriers and facilitators related to the implementation of this requirement. METHODS: During April through November 2019, we conducted three focus groups (n = 12) and eight in-depth semi-structured interviews with parents of children aged 11 and 12 who had not yet initiated the HPV vaccine series. The interview topics addressed were: perception of vaccination, HPV vaccine and it is inclusion as new school entry requirement practice, procedure of the sources of information, influencers, and willingness to change. The interviews were recorded and transcribed by our staff members. We identified emergent themes through thematic analysis. RESULTS: The participants\u27 perspective on the HPV vaccine school requirement was mixed. Lack of information of the HPV vaccines and lack of communication about the school-entry requirement were the themes most mentioned in the interviews. Moreover, previous negative experiences from friends or family members and adverse effects deterred some participants from vaccinating their kids. We discussed barriers in the process of soliciting an exemption. CONCLUSION: Most barriers mentioned by study participants are modifiable. Information about the HPV vaccine mandate\u27s implementation and educational materials regarding HPV vaccine safety need to be provided to address parents\u27 concerns related to the vaccine\u27s side effects. Schools (teachers, principal directors, and administrative staff), the government, and parent organizations need to be part of these efforts. This multilevel approach will help to improve disseminating information about HPV vaccination to clarify doubts and misinformation among parents
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