266 research outputs found

    Can a supernova be located by its neutrinos?

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    A future core-collapse supernova in our Galaxy will be detected by several neutrino detectors around the world. The neutrinos escape from the supernova core over several seconds from the time of collapse, unlike the electromagnetic radiation, emitted from the envelope, which is delayed by a time of order hours. In addition, the electromagnetic radiation can be obscured by dust in the intervening interstellar space. The question therefore arises whether a supernova can be located by its neutrinos alone. The early warning of a supernova and its location might allow greatly improved astronomical observations. The theme of the present work is a careful and realistic assessment of this question, taking into account the statistical significance of the various neutrino signals. Not surprisingly, neutrino-electron forward scattering leads to a good determination of the supernova direction, even in the presence of the large and nearly isotropic background from other reactions. Even with the most pessimistic background assumptions, SuperKamiokande (SK) and the Sudbury Neutrino Observatory (SNO) can restrict the supernova direction to be within circles of radius 5∘5^\circ and 20∘20^\circ, respectively. Other reactions with more events but weaker angular dependence are much less useful for locating the supernova. Finally, there is the oft-discussed possibility of triangulation, i.e., determination of the supernova direction based on an arrival time delay between different detectors. Given the expected statistics we show that, contrary to previous estimates, this technique does not allow a good determination of the supernova direction.Comment: 11 pages including 2 figures. Revised version corrects typos, adds some brief comment

    Brane Big-Bang Brought by Bulk Bubble

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    We propose an alternative inflationary universe scenario in the context of Randall-Sundrum braneworld cosmology. In this new scenario the existence of extra-dimension(s) plays an essential role. First, the brane universe is initially in the inflationary phase driven by the effective cosmological constant induced by small mismatch between the vacuum energy in the 5-dimensional bulk and the brane tension. This mismatch arises since the bulk is initially in a false vacuum. Then, the false vacuum decay occurs, nucleating a true vacuum bubble with negative energy inside the bulk. The nucleated bubble expands in the bulk and consequently hits the brane, bringing a hot big-bang brane universe of the Randall-Sundrum type. Here, the termination of the inflationary phase is due to the change of the bulk vacuum energy. The bubble kinetic energy heats up the universe. As a simple realization, we propose a model, in which we assume an interaction between the brane and the bubble. We derive the constraints on the model parameters taking into account the following requirements: solving the flatness problem, no force which prohibits the bubble from colliding with the brane, sufficiently high reheating temperature for the standard nucleosynthesis to work, and the recovery of Newton's law up to 1mm. We find that a fine tuning is needed in order to satisfy the first and the second requirements simultaneously, although, the other constraints are satisfied in a wide range of the model parameters.Comment: 20pages, 5figures, some references added, the previous manuscript has been largely improve

    Plasma Wakefield Acceleration with a Modulated Proton Bunch

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    The plasma wakefield amplitudes which could be achieved via the modulation of a long proton bunch are investigated. We find that in the limit of long bunches compared to the plasma wavelength, the strength of the accelerating fields is directly proportional to the number of particles in the drive bunch and inversely proportional to the square of the transverse bunch size. The scaling laws were tested and verified in detailed simulations using parameters of existing proton accelerators, and large electric fields were achieved, reaching 1 GV/m for LHC bunches. Energy gains for test electrons beyond 6 TeV were found in this case.Comment: 9 pages, 7 figure

    The energy dependence of ptp_t angular correlations inferred from mean-ptp_{t} fluctuation scale dependence in heavy ion collisions at the SPS and RHIC

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    We present the first study of the energy dependence of ptp_t angular correlations inferred from event-wise mean transverse momentum fluctuations in heavy ion collisions. We compare our large-acceptance measurements at CM energies $\sqrt{s_{NN}} =$ 19.6, 62.4, 130 and 200 GeV to SPS measurements at 12.3 and 17.3 GeV. $p_t$ angular correlation structure suggests that the principal source of $p_t$ correlations and fluctuations is minijets (minimum-bias parton fragments). We observe a dramatic increase in correlations and fluctuations from SPS to RHIC energies, increasing linearly with $\ln \sqrt{s_{NN}}$ from the onset of observable jet-related fluctuations near 10 GeV.Comment: 10 pages, 4 figure

    Evidence of Color Coherence Effects in W+jets Events from ppbar Collisions at sqrt(s) = 1.8 TeV

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    We report the results of a study of color coherence effects in ppbar collisions based on data collected by the D0 detector during the 1994-1995 run of the Fermilab Tevatron Collider, at a center of mass energy sqrt(s) = 1.8 TeV. Initial-to-final state color interference effects are studied by examining particle distribution patterns in events with a W boson and at least one jet. The data are compared to Monte Carlo simulations with different color coherence implementations and to an analytic modified-leading-logarithm perturbative calculation based on the local parton-hadron duality hypothesis.Comment: 13 pages, 6 figures. Submitted to Physics Letters

    Examining the reliability and validity of the Clinical Assessment Interview for Negative Symptoms within the Management of Schizophrenia in Clinical Practice (MOSAIC) multisite national study

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    The current study sought to expand on prior reports of the validity and reliability of the CAINS (CAINS) by examining its performance across diverse non-academic clinical settings as employed by raters not affiliated with the scale's developers and across a longer test-retest follow-up period. The properties of the CAINS were examined within the Management of Schizophrenia in Clinical Practice (MOSAIC) schizophrenia registry. A total of 501 participants with a schizophrenia spectrum diagnosis who were receiving usual care were recruited across 15 national Patient Assessment Centers and evaluated with the CAINS, other negative symptom measures, and assessments of functioning, quality of life and cognition. Temporal stability of negative symptoms was assessed across a 3-month follow-up. Results replicated the two-factor structure of the CAINS reflecting Motivation and Pleasure and expression symptoms. The CAINS scales exhibited high internal consistency and temporal stability. Convergent validity was supported by significant correlations between the CAINS subscales with other negative symptom measures. Additionally, the CAINS was significantly correlated with functioning and quality of life. Discriminant validity was demonstrated by small to moderate associations between the CAINS and positive symptoms, depression, and cognition (and these associations were comparable to those found with other negative symptom scales). Findings suggest that the CAINS is a reliable and valid tool for measuring negative symptoms in schizophrenia across diverse clinical samples and settings

    Robust and prototypical immune responses toward COVID-19 vaccine in First Nations peoples are impacted by comorbidities.

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    High-risk groups, including Indigenous people, are at risk of severe COVID-19. Here we found that Australian First Nations peoples elicit effective immune responses to COVID-19 BNT162b2 vaccination, including neutralizing antibodies, receptor-binding domain (RBD) antibodies, SARS-CoV-2 spike-specific B cells, and CD4âș and CD8âș T cells. In First Nations participants, RBD IgG antibody titers were correlated with body mass index and negatively correlated with age. Reduced RBD antibodies, spike-specific B cells and follicular helper T cells were found in vaccinated participants with chronic conditions (diabetes, renal disease) and were strongly associated with altered glycosylation of IgG and increased interleukin-18 levels in the plasma. These immune perturbations were also found in non-Indigenous people with comorbidities, indicating that they were related to comorbidities rather than ethnicity. However, our study is of a great importance to First Nations peoples who have disproportionate rates of chronic comorbidities and provides evidence of robust immune responses after COVID-19 vaccination in Indigenous people.Wuji Zhang, Lukasz Kedzierski, Brendon Y. Chua, Mark Mayo, Claire Lonzi, Vanessa Rigas, Bianca F. Middleton, Hayley A. McQuilten, Louise C. Rowntree, Lilith F. Allen, Ruth A. Purcell, Hyon-Xhi Tan, Jan Petersen, Priyanka Chaurasia, Francesca Mordant, Mikhail V. Pogorelyy, Anastasia A. Minervina, Jeremy Chase Crawford, Griffith B. Perkins, Eva Zhang, Stephanie Gras, E. Bridie Clemens, Jennifer A. Juno, Jennifer Audsley, David S. Khoury, Natasha E. Holmes, Irani Thevarajan, Kanta Subbarao, Florian Krammer, Allen C. Cheng, Miles P. Davenport, Branka Grubor-Bauk, P. Toby Coates, Britt Christensen, Paul G. Thomas, Adam K. Wheatley, Stephen J. Kent, Jamie Rossjohn, Amy W. Chung, John Boffa, Adrian Miller, Sarah Lynar, Jane Nelson, Thi H. O. Nguyen, Jane Davies, Katherine Kedziersk

    Inflation and Braneworlds: Degeneracies and Consistencies

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    Scalar and tensor perturbations arising in an inflationary braneworld scenario driven by a single scalar field are considered, where the bulk on either side of the brane corresponds to Anti-de Sitter spaces with different cosmological constants. A consistency relation between the two spectra is derived and found to have an identical form to that arising in standard single-field inflation based on conventional Einstein gravity. The dS/CFT correspondence may provide further insight into the origin of this degeneracy. Possible ways of lifting such a degeneracy are discussed.Comment: 10 page

    Gender norms and social norms: differences, similarities and why they matter in prevention science.

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    Two streams of theory and practice on gender equity have begun to elide. The first is work conducted to change social norms, particularly using theory that emerged from studies in social psychology. The second is work done on gender norms, emerging historically from feminist scholars working to counter gender inequality. As these two streams of work intersect, conceptual clarity is needed to understand differences and similarities between these two traditions. Increased clarity will improve efforts to address harmful norms and practices. In this article, we review similarities and differences between social and gender norms, reviewing the history of the concepts and identifying key tension points of contrast. We identified six areas of comparison that might be helpful for practitioners working for the promotion of global health as they make sense of social and gender norms. We then offer a definition of gender norms for practitioners and researchers working at the intersection between these two theories. Our definition draws from the two different streams of thought of how norms influence people's actions, acknowledging the double nature of gender norms: beliefs nested in people's minds and embedded in institutions that profoundly affect health-related behaviours and shape differential access to health services

    Search for electroweak production of single top quarks in ppˉp\bar{p} collisions.

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    We present a search for electroweak production of single top quarks in the electron+jets and muon+jets decay channels. The measurements use ~90 pb^-1 of data from Run 1 of the Fermilab Tevatron collider, collected at 1.8 TeV with the DZero detector between 1992 and 1995. We use events that include a tagging muon, implying the presence of a b jet, to set an upper limit at the 95% confidence level on the cross section for the s-channel process ppbar->tb+X of 39 pb. The upper limit for the t-channel process ppbar->tqb+X is 58 pb. (arXiv
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