2,347 research outputs found

    Probing Majorana neutrinos in rare K and D, D_s, B, B_c meson decays

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    We study lepton number violating decays of charged K, D, D_s, B and B_c mesons of the form M^+\to {M'}^-\ell^+\ell^+, induced by the existence of Majorana neutrinos. These processes provide information complementary to neutrinoless double nuclear beta decays, and are sensitive to neutrino masses and lepton mixing. We explore neutrino mass ranges m_N from below 1 eV to several hundred GeV. We find that in many cases the branching ratios are prohibitively small, however in the intermediate range m_\pi < m_N < m_{B_c}, in specific channels and for specific neutrino masses, the branching ratios can be at the reach of high luminosity experiments like those at the LHC-b and future Super flavor-factories, and can provide bounds on the lepton mixing parameters.Comment: 25 page

    s-Process Nucleosynthesis in Advanced Burning Phases of Massive Stars

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    We present a detailed study of s-process nucleosynthesis in massive stars of solar-like initial composition and masses 15, 20,25, and 30 Msun. We update our previous results of s-process nucleosynthesis during the core He-burning of these stars and then focus on an analysis of the s-process under the physical conditions encountered during the shell-carbon burning. We show that the recent compilation of the Ne22(alpha,n)Mg25 rate leads to a remarkable reduction of the efficiency of the s-process during core He-burning. In particular, this rate leads to the lowest overproduction factor of Kr80 found to date during core He-burning in massive stars. The s-process yields resulting from shell carbon burning turn out to be very sensitive to the structural evolution of the carbon shell. This structure is influenced by the mass fraction of C12 attained at the end of core helium burning, which in turn is mainly determined by the C12(alpha,gamma)O16 reaction. The still present uncertainty in the rate for this reaction implies that the s-process in massive stars is also subject to this uncertainty. We identify some isotopes like Zn70 and Rb87 as the signatures of the s-process during shell carbon burning in massive stars. In determining the relative contribution of our s-only stellar yields to the solar abundances, we find it is important to take into account the neutron exposure of shell carbon burning. When we analyze our yields with a Salpeter Initial Mass Function, we find that massive stars contribute at least 40% to s-only nuclei with mass A 90, massive stars contribute on average ~7%, except for Gd152, Os187, and Hg198 which are ~14%, \~13%, and ~11%, respectively.Comment: 52 pages, 16 figures, accepted for publication in Ap

    Tiffs, tosses, and turns:Effects of affective reactivity to interpersonal stressors during the day on nightly sleep

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    BackgroundSleep has been recognized as an antecedent as well as a consequence of daytime stress. However, less research has compared the role of different stressor types on same-night sleep in the context of daily life. Interpersonal stressors may be particularly important, given that social stressors to elicit greater stress responses than other forms of stressors. This study tested the hypothesis that following days when a person exhibits greater negative affect (NA) reactivity to stressors (versus on days with less NA reactivity), sleep quality will be lower. This link between affective reactivity to stressors and subsequent sleep was expected to be more pronounced for interpersonal stressors versus non-interpersonal stressors.MethodsIn this pre-registered study, 252 adults in British Columbia, Canada (ages 25 to 87y; 68% women; 64% White) completed mobile surveys 5x/day for 14 days to assess daily stressors and NA. Self-reported sleep quality was assessed in morning surveys. Multilevel-models tested daily stressors (interpersonal, non-interpersonal, or no stressors), daily NA (averaged across the day), and their interaction as predictors of subsequent sleep quality, controlling for prior-night sleep quality and sociodemographics.ResultsDaily NA and stressor occurrence independently predicted poorer subsequent sleep quality. Stressor type moderated the relationship between NA and sleep quality, such that this association was stronger for interpersonal compared to non-interpersonal stressors.DiscussionThe findings suggest that encountering interpersonal stressors may be particularly impactful to one’s subsequent sleep. Future studies should consider investigating potential mechanisms that may underlie this association, such as pre-sleep cognitive, emotional, and physiological arousal

    A Dual Geometry of the Hadron in Dense Matter

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    We identify the dual geometry of the hadron phase of dense nuclear matter and investigate the confinement/deconfinement phase transition. We suggest that the low temperature phase of the RN black hole with the full backreaction of the bulk gauge field is described by the zero mass limit of the RN black hole with hard wall. We calculated the density dependence of critical temperature and found that the phase diagram closes. We also study the density dependence of the rho meson mass.Comment: 16 pages, 4 figures, typos corrected, references adde

    μτ\mu-\tau Symmetry and Radiatively Generated Leptogenesis

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    We consider a μτ\mu-\tau symmetry in neutrino sectors realized at GUT scale in the context of a seesaw model. In our scenario, the exact μτ\mu-\tau symmetry realized in the basis where the charged lepton and heavy Majorana neutrino mass matrices are diagonal leads to vanishing lepton asymmetries. We find that, in the minimal supersymmetric extension of the seesaw model with large tanβ\tan\beta, the renormalization group (RG) evolution from GUT scale to seesaw scale can induce a successful leptogenesis even without introducing any symmetry breaking terms by hand, whereas such RG effects lead to tiny deviations of θ23\theta_{23} and θ13\theta_{13} from π/4\pi/4 and zero, respectively. It is shown that the right amount of the baryon asymmetry ηB\eta_B can be achieved via so-called resonant leptogenesis, which can be realized at rather low seesaw scale with large tanβ\tan\beta in our scenario so that the well-known gravitino problem is safely avoided.Comment: 17 pages, 5 figures. Published in PR

    Water Quality, Aquatic Life and Fish in Song Bung River. A Part Study of the Environmental Impact Assesment for the Song Bung 4 Hydropower Development Project in Central Vietnam

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    Årsliste 2007The study comprise three main tasks: 1) Assess the present situation in the river with respect to water quality, aquatic life, fish and fishery; 2) Assess the impact of the hydropower regulation scheme on these items, and 3) Propose and outline mitigation measures to reduce the negative impacts. The study also deals with impact from mining and how this will conflict with the regulation plans. It also elucidates the potential for releases of greenhouse gases from the reservoir. Finally the study proposes a monitoring programme, as well as Terms of Reference for a study of the aquatic resources in the whole Vu Gia River system.Asian Development Ban

    An Update of Weed Flora of Vıneyards ın Northwestern Turkey

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    The weed flora of vineyards in northwestern Turkey was determined in a survey carried out in 93 vineyards. Total of 68 species 53 dicotyledonous and 11 monocotyledonous belonging to 32 families were identified in grape growing areas. The majority of weed species were annual species with different vegetation periods. The dominant weed species in the region were Capsella bursa pastoris, Convolvulus arvensis, Senecio vulgaris, Stellaria media, Sorghum halepense, Euphorbia helioscopia. Meanwhile frequent families were Poaceae, Asteraceae, Brassicaceae, Fabaceae, Geraniaceae, Lamiaceae, Polygonaceae and Euphorbiaceae

    A systematic review and meta-analysis of the gonadotoxic effects of cyclophosphamide and benefits of gonadotropin releasing hormone agonists (GnRHa) in women of child-bearing age with autoimmune rheumatic disease

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    Objectives: To systematically review the risk of sustained amenorrhoea with intravenous (IV) cyclophosphamide in autoimmune rheumatic disease (ARD), and evaluate the efficacy of gonadotropin releasing hormone agonists (GnRHa) to reduce this risk. / Methods: Systematic search for papers reporting the incidence of sustained amenorrhoea ≥ 12 months in ARD following: IV cyclophosphamide; or GnRHa and IV cyclophosphamide compared to IV cyclophosphamide alone. / Results: From 31 articles and 1388 patients with a mean age of 27.7 years, sustained amenorrhoea occurred in 273 patients (19.7%). Of 56 patients (mean age range 23.9-25.6 years) receiving GnRHa and IV cyclophosphamide, and 37 controls (mean age range 25-30.1 years) given IV cyclophosphamide only, sustained amenorrhoea occurred in 2/56 (3.6%) patients treated with GnRHa, compared to 15/37 (40.5%) controls. Pooled odds ratio of sustained amenorrhoea with GnRHa and cyclophosphamide versus cyclophosphamide alone was 0.054 (95% CI 0.0115-0.2576 p<0.001), corresponding to a number needed to treat of 2.7 (95% CI 1.955-4.388) and absolute risk reduction of 36.95% (95% CI 35.6-38.4%). / Conclusion: Sustained amenorrhoea with IV cyclophosphamide was observed in patients with ARD, especially with increasing age and cumulative doses >5g. GnRHa reduced this risk and should be considered with IV cyclophosphamide in women of childbearing age with ARD

    Fluctuation theorem for constrained equilibrium systems

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    We discuss the fluctuation properties of equilibrium chaotic systems with constraints such as iso-kinetic and Nos\'e-Hoover thermostats. Although the dynamics of these systems does not typically preserve phase-space volumes, the average phase-space contraction rate vanishes, so that the stationary states are smooth. Nevertheless finite-time averages of the phase-space contraction rate have non-trivial fluctuations which we show satisfy a simple version of the Gallavotti-Cohen fluctuation theorem, complementary to the usual fluctuation theorem for non-equilibrium stationary states, and appropriate to constrained equilibrium states. Moreover we show these fluctuations are distributed according to a Gaussian curve for long-enough times. Three different systems are considered here, namely (i) a fluid composed of particles interacting with Lennard-Jones potentials; (ii) a harmonic oscillator with Nos\'e-Hoover thermostatting; (iii) a simple hyperbolic two-dimensional map.Comment: To appear in Phys. Rev.
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