2,347 research outputs found
Probing Majorana neutrinos in rare K and D, D_s, B, B_c meson decays
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
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
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
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
Symmetry and Radiatively Generated Leptogenesis
We consider a symmetry in neutrino sectors realized at GUT scale
in the context of a seesaw model. In our scenario, the exact
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 , 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 and from and zero,
respectively. It is shown that the right amount of the baryon asymmetry
can be achieved via so-called resonant leptogenesis, which can be
realized at rather low seesaw scale with large 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
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
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
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
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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