371 research outputs found

    Coulomb corrections to bremsstrahlung in electric field of heavy atom at high energies

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    The differential and partially integrated cross sections are considered for bremsstrahlung from high-energy electrons in atomic field with the exact account of this field. The consideration exploits the quasiclassical electron Green's function and wave functions in an external electric field. It is shown that the Coulomb corrections to the differential cross section are very susceptible to screening. Nevertheless, the Coulomb corrections to the cross section summed up over the final-electron states are independent of screening in the leading approximation over a small parameter 1/mrscr1/mr_{scr} (rscrr_{scr} is a screening radius, mm is the electron mass, =c=1\hbar=c=1). Bremsstrahlung from an electron beam of the finite size on heavy nucleus is considered as well. Again, the Coulomb corrections to the differential probability are very susceptible to the beam shape, while those to the probability integrated over momentum transfer are independent of it, apart from the trivial factor, which is the electron-beam density at zero impact parameter. For the Coulomb corrections to the bremsstrahlung spectrum, the next-to-leading terms with respect to the parameters m/ϵm/\epsilon (ϵ\epsilon is the electron energy) and 1/mrscr1/mr_{scr} are obtained.Comment: 13 pages, 4 figure

    Protein kinase CK2 localizes to sites of DNA double-strand break regulating the cellular response to DNA damage

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    <p>Abstract</p> <p>Background</p> <p>The DNA-dependent protein kinase (DNA-PK) is a nuclear complex composed of a large catalytic subunit (DNA-PKcs) and a heterodimeric DNA-targeting subunit Ku. DNA-PK is a major component of the non-homologous end-joining (NHEJ) repair mechanism, which is activated in the presence of DNA double-strand breaks induced by ionizing radiation, reactive oxygen species and radiomimetic drugs. We have recently reported that down-regulation of protein kinase CK2 by siRNA interference results in enhanced cell death specifically in DNA-PKcs-proficient human glioblastoma cells, and this event is accompanied by decreased autophosphorylation of DNA-PKcs at S2056 and delayed repair of DNA double-strand breaks.</p> <p>Results</p> <p>In the present study, we show that CK2 co-localizes with phosphorylated histone H2AX to sites of DNA damage and while CK2 gene knockdown is associated with delayed DNA damage repair, its overexpression accelerates this process. We report for the first time evidence that lack of CK2 destabilizes the interaction of DNA-PKcs with DNA and with Ku80 at sites of genetic lesions. Furthermore, we show that CK2 regulates the phosphorylation levels of DNA-PKcs only in response to direct induction of DNA double-strand breaks.</p> <p>Conclusions</p> <p>Taken together, these results strongly indicate that CK2 plays a prominent role in NHEJ by facilitating and/or stabilizing the binding of DNA-PKcs and, possibly other repair proteins, to the DNA ends contributing to efficient DNA damage repair in mammalian cells.</p

    Unfolding the Hierarchy of Voids

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    We present a framework for the hierarchical identification and characterization of voids based on the Watershed Void Finder. The Hierarchical Void Finder is based on a generalization of the scale space of a density field invoked in order to trace the hierarchical nature and structure of cosmological voids. At each level of the hierarchy, the watershed transform is used to identify the voids at that particular scale. By identifying the overlapping regions between watershed basins in adjacent levels, the hierarchical void tree is constructed. Applications on a hierarchical Voronoi model and on a set of cosmological simulations illustrate its potential.Comment: 5 pages, 2 figure

    Evidence for CP Violation in the Decay D+KS0π+D^+\rightarrow K^0_S\pi^+

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    We observe evidence for CP violation in the decay D+KS0π+D^+\rightarrow K^0_S\pi^+ using a data sample with an integrated luminosity of 977 fb1^{-1} collected by the Belle detector at the KEKB e+ee^+e^- asymmetric-energy collider. The CP asymmetry in the decay is measured to be (0.363±0.094±0.067)(-0.363\pm0.094\pm0.067)%, which is 3.2 standard deviations away from zero, and is consistent with the expected CP violation due to the neutral kaon in the final state.Comment: 6 pages, 3 figure

    The HyVac4 Subunit Vaccine Efficiently Boosts BCG-Primed Anti-Mycobacterial Protective Immunity

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    BACKGROUND: The current vaccine against tuberculosis (TB), BCG, has failed to control TB worldwide and the protective efficacy is moreover limited to 10-15 years. A vaccine that could efficiently boost a BCG-induced immune response and thus prolong protective immunity would therefore have a significant impact on the global TB-burden. METHODS/FINDINGS: In the present study we show that the fusion protein HyVac4 (H4), consisting of the mycobacterial antigens Ag85B and TB10.4, given in the adjuvant IC31® or DDA/MPL effectively boosted and prolonged immunity induced by BCG, leading to improved protection against infection with virulent M. tuberculosis (M.tb). Increased protection correlated with an increased percentage of TB10.4 specific IFNγ/TNFα/IL-2 or TNFα/IL-2 producing CD4 T cells at the site of infection. Moreover, this vaccine strategy did not compromise the use of ESAT-6 as an accurate correlate of disease development/vaccine efficacy. Indeed both CD4 and CD8 ESAT-6 specific T cells showed significant correlation with bacterial levels. CONCLUSIONS/SIGNIFICANCE: H4-IC31® can efficiently boost BCG-primed immunity leading to an increased protective anti-M.tb immune response dominated by IFNγ/TNFα/IL-2 or TNFα/IL2 producing CD4 T cells. H4 in the CD4 T cell inducing adjuvant IC31® is presently in clinical trials

    4 f(P1) giant dipole resonance in La³⁺

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    Photoabsorption of free La3+ ions in the 4d excitation region has been measured using the dual-laser plasma technique. A dramatic strong and broad 4d94f(1P) giant dipole resonance was observed. The interpretation of the results is provided using theoretical techniques which go beyond the independent particle approximation. In particular the strong term dependence for 4f(1P) gives evidence of strong polarization effects for the description of the giant dipole resonance

    Regularity Properties and Pathologies of Position-Space Renormalization-Group Transformations

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    We reconsider the conceptual foundations of the renormalization-group (RG) formalism, and prove some rigorous theorems on the regularity properties and possible pathologies of the RG map. Regarding regularity, we show that the RG map, defined on a suitable space of interactions (= formal Hamiltonians), is always single-valued and Lipschitz continuous on its domain of definition. This rules out a recently proposed scenario for the RG description of first-order phase transitions. On the pathological side, we make rigorous some arguments of Griffiths, Pearce and Israel, and prove in several cases that the renormalized measure is not a Gibbs measure for any reasonable interaction. This means that the RG map is ill-defined, and that the conventional RG description of first-order phase transitions is not universally valid. For decimation or Kadanoff transformations applied to the Ising model in dimension d3d \ge 3, these pathologies occur in a full neighborhood {β>β0,h<ϵ(β)}\{ \beta > \beta_0 ,\, |h| < \epsilon(\beta) \} of the low-temperature part of the first-order phase-transition surface. For block-averaging transformations applied to the Ising model in dimension d2d \ge 2, the pathologies occur at low temperatures for arbitrary magnetic-field strength. Pathologies may also occur in the critical region for Ising models in dimension d4d \ge 4. We discuss in detail the distinction between Gibbsian and non-Gibbsian measures, and give a rather complete catalogue of the known examples. Finally, we discuss the heuristic and numerical evidence on RG pathologies in the light of our rigorous theorems.Comment: 273 pages including 14 figures, Postscript, See also ftp.scri.fsu.edu:hep-lat/papers/9210/9210032.ps.

    Global, regional, and national comparative risk assessment of 79 behavioural, environmental and occupational, and metabolic risks or clusters of risks, 1990-2015: a systematic analysis for the Global Burden of Disease Study 2015

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    SummaryBackground The Global Burden of Diseases, Injuries, and Risk Factors Study 2015 provides an up-to-date synthesis of the evidence for risk factor exposure and the attributable burden of disease. By providing national and subnational assessments spanning the past 25 years, this study can inform debates on the importance of addressing risks in context. Methods We used the comparative risk assessment framework developed for previous iterations of the Global Burden of Disease Study to estimate attributable deaths, disability-adjusted life-years (DALYs), and trends in exposure by age group, sex, year, and geography for 79 behavioural, environmental and occupational, and metabolic risks or clusters of risks from 1990 to 2015. This study included 388 risk-outcome pairs that met World Cancer Research Fund-defined criteria for convincing or probable evidence. We extracted relative risk and exposure estimates from randomised controlled trials, cohorts, pooled cohorts, household surveys, census data, satellite data, and other sources. We used statistical models to pool data, adjust for bias, and incorporate covariates. We developed a metric that allows comparisons of exposure across risk factors—the summary exposure value. Using the counterfactual scenario of theoretical minimum risk level, we estimated the portion of deaths and DALYs that could be attributed to a given risk. We decomposed trends in attributable burden into contributions from population growth, population age structure, risk exposure, and risk-deleted cause-specific DALY rates. We characterised risk exposure in relation to a Socio-demographic Index (SDI). Findings Between 1990 and 2015, global exposure to unsafe sanitation, household air pollution, childhood underweight, childhood stunting, and smoking each decreased by more than 25%. Global exposure for several occupational risks, high body-mass index (BMI), and drug use increased by more than 25% over the same period. All risks jointly evaluated in 2015 accounted for 57·8% (95% CI 56·6–58·8) of global deaths and 41·2% (39·8–42·8) of DALYs. In 2015, the ten largest contributors to global DALYs among Level 3 risks were high systolic blood pressure (211·8 million [192·7 million to 231·1 million] global DALYs), smoking (148·6 million [134·2 million to 163·1 million]), high fasting plasma glucose (143·1 million [125·1 million to 163·5 million]), high BMI (120·1 million [83·8 million to 158·4 million]), childhood undernutrition (113·3 million [103·9 million to 123·4 million]), ambient particulate matter (103·1 million [90·8 million to 115·1 million]), high total cholesterol (88·7 million [74·6 million to 105·7 million]), household air pollution (85·6 million [66·7 million to 106·1 million]), alcohol use (85·0 million [77·2 million to 93·0 million]), and diets high in sodium (83·0 million [49·3 million to 127·5 million]). From 1990 to 2015, attributable DALYs declined for micronutrient deficiencies, childhood undernutrition, unsafe sanitation and water, and household air pollution; reductions in risk-deleted DALY rates rather than reductions in exposure drove these declines. Rising exposure contributed to notable increases in attributable DALYs from high BMI, high fasting plasma glucose, occupational carcinogens, and drug use. Environmental risks and childhood undernutrition declined steadily with SDI; low physical activity, high BMI, and high fasting plasma glucose increased with SDI. In 119 countries, metabolic risks, such as high BMI and fasting plasma glucose, contributed the most attributable DALYs in 2015. Regionally, smoking still ranked among the leading five risk factors for attributable DALYs in 109 countries; childhood underweight and unsafe sex remained primary drivers of early death and disability in much of sub-Saharan Africa. Interpretation Declines in some key environmental risks have contributed to declines in critical infectious diseases. Some risks appear to be invariant to SDI. Increasing risks, including high BMI, high fasting plasma glucose, drug use, and some occupational exposures, contribute to rising burden from some conditions, but also provide opportunities for intervention. Some highly preventable risks, such as smoking, remain major causes of attributable DALYs, even as exposure is declining. Public policy makers need to pay attention to the risks that are increasingly major contributors to global burden. Funding Bill & Melinda Gates Foundation

    Observation of the electromagnetic doubly OZI-suppressed decay J/ψϕπ0J/\psi \rightarrow \phi \pi^{0}

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    Using a sample of 1.311.31 billion J/ψJ/\psi events accumulated with the BESIII detector at the BEPCII collider, we report the observation of the decay J/ψϕπ0J/\psi \rightarrow \phi\pi^{0}, which is the first evidence for a doubly Okubo-Zweig-Iizuka suppressed electromagnetic J/ψJ/\psi decay. A clear structure is observed in the K+KK^{+} K^{-} mass spectrum around 1.02 GeV/c2c^2, which can be attributed to interference between J/ψϕπ0J/\psi \rightarrow \phi\pi^{0} and J/ψK+Kπ0J/\psi \rightarrow K^{+}K^{-}\pi^{0} decays. Due to this interference, two possible solutions are found. The corresponding measured values of the branching fraction of J/ψϕπ0J/\psi \to \phi\pi^{0} are [2.94±0.16(stat.)±0.16(syst.)]×106[2.94 \pm 0.16\text{(stat.)} \pm 0.16\text{(syst.)}] \times 10^{-6} and [1.24±0.33(stat.)±0.30(syst.)]×107[1.24 \pm 0.33\text{(stat.)} \pm 0.30\text{(syst.)}] \times 10^{-7}.Comment: 7 pages, 4 figures, published in Phys. Rev.

    Search for Kaluza-Klein Graviton Emission in ppˉp\bar{p} Collisions at s=1.8\sqrt{s}=1.8 TeV using the Missing Energy Signature

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    We report on a search for direct Kaluza-Klein graviton production in a data sample of 84 pb1{pb}^{-1} of \ppb collisions at s\sqrt{s} = 1.8 TeV, recorded by the Collider Detector at Fermilab. We investigate the final state of large missing transverse energy and one or two high energy jets. We compare the data with the predictions from a 3+1+n3+1+n-dimensional Kaluza-Klein scenario in which gravity becomes strong at the TeV scale. At 95% confidence level (C.L.) for nn=2, 4, and 6 we exclude an effective Planck scale below 1.0, 0.77, and 0.71 TeV, respectively.Comment: Submitted to PRL, 7 pages 4 figures/Revision includes 5 figure
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