1,510 research outputs found

    The Current-Temperature Phase Diagram of Layered Superconductors

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    The behavior of clean layered superconductors in the presence of a finite electric current and in zero-magnetic field behavior is addressed. The structure of the current temperature phase diagram and the properties of each of the four regions will be explained. We will discuss the expected current voltage and resistance characteristics of each region as well as the effects of finite size and weak disorder on the phase diagram. In addition, the reason for which a weakly non-ohmic region exists above the transition temperature will be explained.Comment: 8 pages (RevTeX), 4 encapsulated postscript figure

    QCD Coherence and the Top Quark Asymmetry

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    Coherent QCD radiation in the hadroproduction of top quark pairs leads to a forward--backward asymmetry that grows more negative with increasing transverse momentum of the pair. This feature is present in Monte Carlo event generators with coherent parton showering, even though the production process is treated at leading order and has no intrinsic asymmetry before showering. In addition, depending on the treatment of recoils, showering can produce a positive contribution to the inclusive asymmetry. We explain the origin of these features, compare them in fixed-order calculations and the Herwig++, Pythia and Sherpa event generators, and discuss their implications.Comment: 28 pages, 11 figures, 2 table

    Anxiety and self-esteem as mediators of the relation between family communication and indecisiveness in adolescence

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    Abstract In this study, we explored the unique and common contributions of anxiety, self-esteem, and family communication on indecisiveness among adolescents. Three hundred and fifty pupils from 13 to 16 years of age completed selfreport measures on indecisiveness, quality of family communication, trait anxiety, and self-esteem. The findings in this study showed that students\u2019 indecisiveness is predicted by family communication mediated by anxiety and self-esteem. These results have important implications for practice as it stresses the importance of anxiety and self-esteem. Nevertheless, the counselors could also focus on enhancing relationship-building skills by introducing the adolescents\u2019 career formation as an adolescent\u2013parent joint project.L\u2019anxie\ub4te\ub4 et l\u2019estime de soi comme me\ub4diateurs de la relation entre communication au sein de la famille et indecision chronique a` l\u2019adolescence. Dans cette e\ub4tude, nous avons explore\ub4 les contributions uniques et communes de l\u2019anxiete\ub4, de l\u2019estime de soi et de la communication au sein de la famille sur l\u2019indecision chronique aupres d\u2019adolescents. Trois cent cinquante e\ub4le`ves a\u2c6ge\ub4s de 13 a` 16 ans ont rempli des mesures d\u2019auto-e\ub4valuation de l\u2019inde\ub4cision chronique, de la qualite\ub4 de la communication familiale, de l\u2019anxie\ub4te\ub4-trait et de l\u2019estime de soi. Les re\ub4sultats de cette e\ub4tude ont montre\ub4 que l\u2019inde\ub4cision des e\ub4tudiants est explique\ub4e par la communication au sein de la famille et que ce lien est me\ub4diatise\ub4 par l\u2019anxie\ub4te\ub4 et l\u2019estime de soi. Ces re\ub4sultats ont des implications importantes pour la pratique car ils soulignent l\u2019importance de l\u2019anxie\ub4te\ub4 et l\u2019estime de soi. Ne\ub4anmoins, les conseillers pourraient e\ub4galement se concentrer sur l\u2019ame\ub4lioration des compe\ub4tences de construction relationnelle en introduisant la formation professionnelle des adolescents comme un projet conjoint adolescent-parent.Resumen. Ansiedad y Autoestima como Mediadores de la Relacio\ub4n entre Comunicacio\ub4n Familiar e Indecisio\ub4n en la Adolescencia. En este estudio, exploramos las contribuciones u\ub4nicas y comunes de la ansiedad, la autoestima y la comunicacio\ub4n de familia en la indecisio\ub4n de los adolescentes. Tres y cientos cincuenta alumnos entre los 13 y 16 an\u2dcos completaron auto-evaluaciones sobre la indecisio\ub4n, la calidad de comunicacio\ub4n familiar, los rasgos de ansiedad y la autoestima. Los resultados en este estudio muestran que la indecisio\ub4n en los estudiantes es prevista por la comunicacio\ub4n familiar mediada por la ansiedad y la autoestima. Estos resultados tiene importantes implicaciones para la practica ya que destacan la importancia de la ansiedad y la autoestima. Sin embargo, los consejeros podr\u131\ub4an tambie\ub4n focalizarse en el aumento de sus habilidades para construir relaciones mediante la introduccio\ub4n de la formacio\ub4n profesional para adolescentes como un proyecto conjunto del adolescente-padre.Angst und Selbstwertgefu\ua8 hl als Mediatoren der Beziehung zwischen Kommunikation in der Familie und Unentschlossenheit in der Adoleszenz. In dieser Studie untersuchten wir die spezifischen und gemeinsamen Beitra\ua8ge von Angst, Selbstwertgefu\ua8hl und Kommunikation in der Familie auf Unentschlossenheit unter Jugendlichen. Dreihundertfu\ua8nfzig Schu\ua8ler, zwischen 13 bis 16 Jahre alt, fu\ua8llten Skalen zur Unentschlossenheit, Qualita\ua8t der Kommunikation in der Familie, A\ua8 ngstlichkeit und Selbstwertgefu\ua8hl aus. Die Ergebnisse dieser Studie zeigten, dass Unentschlossenheit der Schu\ua8ler von Kommunikation in der Familie vorhergesagt wird, vermittelt durch Angst und Selbstwertgefu\ua8 hl. Diese Ergebnisse haben wichtige Implikationen fu\ua8r die Praxis, da sie die Bedeutung von Angst und Selbstwertgefu\ua8hl hervorheben. Dennoch ko\ua8nnten sich die Beratungspersonen durch die Einfu\ua8hrung der beruflichen Bildung der Jugendlichen als ein gemeinsames Projekt von Jugendliche-Elternteil auch auf die Verbesserung der Fa\ua8higkeiten zum Aufbau von Beziehungen konzentrieren

    Search for chargino-neutralino production with mass splittings near the electroweak scale in three-lepton final states in √s=13 TeV pp collisions with the ATLAS detector

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    A search for supersymmetry through the pair production of electroweakinos with mass splittings near the electroweak scale and decaying via on-shell W and Z bosons is presented for a three-lepton final state. The analyzed proton-proton collision data taken at a center-of-mass energy of √s=13  TeV were collected between 2015 and 2018 by the ATLAS experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 139  fb−1. A search, emulating the recursive jigsaw reconstruction technique with easily reproducible laboratory-frame variables, is performed. The two excesses observed in the 2015–2016 data recursive jigsaw analysis in the low-mass three-lepton phase space are reproduced. Results with the full data set are in agreement with the Standard Model expectations. They are interpreted to set exclusion limits at the 95% confidence level on simplified models of chargino-neutralino pair production for masses up to 345 GeV

    Search for direct stau production in events with two hadronic tau-leptons in root s=13 TeV pp collisions with the ATLAS detector

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    A search for the direct production of the supersymmetric partners ofτ-leptons (staus) in final stateswith two hadronically decayingτ-leptons is presented. The analysis uses a dataset of pp collisions corresponding to an integrated luminosity of139fb−1, recorded with the ATLAS detector at the LargeHadron Collider at a center-of-mass energy of 13 TeV. No significant deviation from the expected StandardModel background is observed. Limits are derived in scenarios of direct production of stau pairs with eachstau decaying into the stable lightest neutralino and oneτ-lepton in simplified models where the two staumass eigenstates are degenerate. Stau masses from 120 GeV to 390 GeV are excluded at 95% confidencelevel for a massless lightest neutralino

    Utilisation of an operative difficulty grading scale for laparoscopic cholecystectomy

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    Background A reliable system for grading operative difficulty of laparoscopic cholecystectomy would standardise description of findings and reporting of outcomes. The aim of this study was to validate a difficulty grading system (Nassar scale), testing its applicability and consistency in two large prospective datasets. Methods Patient and disease-related variables and 30-day outcomes were identified in two prospective cholecystectomy databases: the multi-centre prospective cohort of 8820 patients from the recent CholeS Study and the single-surgeon series containing 4089 patients. Operative data and patient outcomes were correlated with Nassar operative difficultly scale, using Kendall’s tau for dichotomous variables, or Jonckheere–Terpstra tests for continuous variables. A ROC curve analysis was performed, to quantify the predictive accuracy of the scale for each outcome, with continuous outcomes dichotomised, prior to analysis. Results A higher operative difficulty grade was consistently associated with worse outcomes for the patients in both the reference and CholeS cohorts. The median length of stay increased from 0 to 4 days, and the 30-day complication rate from 7.6 to 24.4% as the difficulty grade increased from 1 to 4/5 (both p < 0.001). In the CholeS cohort, a higher difficulty grade was found to be most strongly associated with conversion to open and 30-day mortality (AUROC = 0.903, 0.822, respectively). On multivariable analysis, the Nassar operative difficultly scale was found to be a significant independent predictor of operative duration, conversion to open surgery, 30-day complications and 30-day reintervention (all p < 0.001). Conclusion We have shown that an operative difficulty scale can standardise the description of operative findings by multiple grades of surgeons to facilitate audit, training assessment and research. It provides a tool for reporting operative findings, disease severity and technical difficulty and can be utilised in future research to reliably compare outcomes according to case mix and intra-operative difficulty

    Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at √ s = 8 TeV with the ATLAS detector

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    Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fb−1 of √ s = 8 TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with pT > 120 GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between Emiss T > 150 GeV and Emiss T > 700 GeV. Good agreement is observed between the number of events in data and Standard Model expectations. The results are translated into exclusion limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. In addition, limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presente

    Obstetric professionals’ perceptions of non-invasive prenatal testing for Down syndrome: clinical usefulness compared with existing tests and ethical implications

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    Background: While non-invasive prenatal testing (NIPT) for fetal aneuploidy is commercially available in many countries, little is known about how obstetric professionals in non-Western populations perceive the clinical usefulness of NIPT in comparison with existing first-trimester combined screening (FTS) for Down syndrome (DS) or invasive prenatal diagnosis (IPD), or perceptions of their ethical concerns arising from the use of NIPT. Methods: A cross-sectional survey among 327 obstetric professionals (237 midwives, 90 obstetricians) in Hong Kong. Results: Compared to FTS, NIPT was believed to: provide more psychological benefits and enable earlier consideration of termination of pregnancy. Compared to IPD, NIPT was believed to: provide less psychological stress for high-risk women and more psychological assurance for low-risk women, and offer an advantage to detect chromosomal abnormalities earlier. Significant differences in perceived clinical usefulness were found by profession and healthcare sector: (1) obstetricians reported more certain views towards the usefulness of NIPT than midwives and (2) professionals in the public sector perceived less usefulness of NIPT than the private sector. Beliefs about earlier detection of DS using NIPT were associated with ethical concerns about increasing abortion. Participants believing that NIPT provided psychological assurance among low-risk women were less likely to be concerned about ethical issues relating to informed decision-making and pre-test consultation for NIPT. Conclusions: Our findings suggest the need for political debate initially on how to ensure pregnant women accessing public services are informed about commercially available more advanced technology, but also on the potential implementation of NIPT within public services to improve access and equity to DS screening services

    Real-Time Imaging Reveals the Dynamics of Leukocyte Behaviour during Experimental Cerebral Malaria Pathogenesis

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    During experimental cerebral malaria (ECM) mice develop a lethal neuropathological syndrome associated with microcirculatory dysfunction and intravascular leukocyte sequestration. The precise spatio-temporal context in which the intravascular immune response unfolds is incompletely understood. We developed a 2-photon intravital microscopy (2P-IVM)-based brain-imaging model to monitor the real-time behaviour of leukocytes directly within the brain vasculature during ECM. Ly6Chi monocytes, but not neutrophils, started to accumulate in the blood vessels of Plasmodium berghei ANKA (PbA)-infected MacGreen mice, in which myeloid cells express GFP, one to two days prior to the onset of the neurological signs (NS). A decrease in the rolling speed of monocytes, a measure of endothelial cell activation, was associated with progressive worsening of clinical symptoms. Adoptive transfer experiments with defined immune cell subsets in recombinase activating gene (RAG)-1-deficient mice showed that these changes were mediated by Plasmodium-specific CD8+ T lymphocytes. A critical number of CD8+ T effectors was required to induce disease and monocyte adherence to the vasculature. Depletion of monocytes at the onset of disease symptoms resulted in decreased lymphocyte accumulation, suggesting reciprocal effects of monocytes and T cells on their recruitment within the brain. Together, our studies define the real-time kinetics of leukocyte behaviour in the central nervous system during ECM, and reveal a significant role for Plasmodium-specific CD8+ T lymphocytes in regulating vascular pathology in this disease. © 2014 Pai et al

    CD4+ Natural Regulatory T Cells Prevent Experimental Cerebral Malaria via CTLA-4 When Expanded In Vivo

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    Studies in malaria patients indicate that higher frequencies of peripheral blood CD4+ Foxp3+ CD25+ regulatory T (Treg) cells correlate with increased blood parasitemia. This observation implies that Treg cells impair pathogen clearance and thus may be detrimental to the host during infection. In C57BL/6 mice infected with Plasmodium berghei ANKA, depletion of Foxp3+ cells did not improve parasite control or disease outcome. In contrast, elevating frequencies of natural Treg cells in vivo using IL-2/anti-IL-2 complexes resulted in complete protection against severe disease. This protection was entirely dependent upon Foxp3+ cells and resulted in lower parasite biomass, impaired antigen-specific CD4+ T and CD8+ T cell responses that would normally promote parasite tissue sequestration in this model, and reduced recruitment of conventional T cells to the brain. Furthermore, Foxp3+ cell-mediated protection was dependent upon CTLA-4 but not IL-10. These data show that T cell-mediated parasite tissue sequestration can be reduced by regulatory T cells in a mouse model of malaria, thereby limiting malaria-induced immune pathology
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