145 research outputs found
Evidence for enhanced desorption of hydrogen atoms from a Si 100 surface induced by slow highly charged ions
We report evidence for an enhanced desorption of hydrogen atoms from a Si 100 surface bombarded by 30 keV Xeq q 6?22 ions. The measured desorption yield amounts to 0.76 and 2.2 hydrogen atoms per incident Xe10 and Xe18 ion, respectively. For understanding the behaviour of hydrogen desorption from Si, another experiment was carried out to see the hydrogen signals as a function of time for about 140 min after deliberately introducing hydrogen into the target chamber and then shut off the valve. The results are discussed in the light of potential sputtering which essentially dominates for ions at higher charge states and the interpretation is supported by theoretical estimates
B -> X_s gamma gamma and B_s -> gamma gamma in supersymmetry with broken R-parity
We examine the effects of R-parity violating (RPV) supersymmetry on the
two-photon B decays B -> X_s gamma gamma and B_s -> gamma gamma. We find that,
although there are many one-loop RPV diagrams that can contribute to these
two-photon B decays, the RPV effect is dominated by a single diagram. This
diagram, named here lambda-irreducible, has a distinct topology which is
irrelevant for the b -> s gamma amplitude at one-loop and has thus a negligible
effect on the one-photon decay B -> X_s gamma. We show that the
lambda-irreducible RPV diagram can give BR(B_s -> gamma gamma) ~ 5*10^(-6) and
BR(B -> X_s gamma gamma) ~ 6*10^(-7), which is about 16 and 5 times larger than
the SM values, respectively. Although the enhancement to the decay width of B
-> X_s gamma gamma is not that dramatic, we find that the energy distribution
of the two photons is appreciably different from the SM, due to new threshold
effects caused by the distinct topology of the RPV lambda-irreducible diagram.
Moreover, this diagram significantly changes the forward-backward asymmetry
with respect to the softer photon in B -> X_s gamma gamma. Thus, the RPV effect
in B -> X_s gamma gamma can be discerned using these observables.Comment: 12 pages, 6 figure
Impact of CP phases on neutrinoless double beta decay
We highlight in a model independent way the dependence of the effective
Majorana mass parameter, relevant for neutrinoless double beta decay, on the CP
phases of the PMNS matrix, using the most recent neutrino data including the
cosmological WMAP measurement. We perform our analysis with three active
neutrino flavours in the context of three kinds of mass spectra:
quasi-degenerate, normal hierarchical and inverted hierarchical. If a
neutrinoless double beta decay experiment records a positive signal, then
assuming that Majorana masses of light neutrinos are responsible for it, we
show how it might be possible to discriminate between the three kinds of
spectra.Comment: 10 pages, latex, 9 eps figs, version to appear in Phys Rev
Mass Parameterizations and Predictions of Isotopic Observables
We discuss the accuracy of mass models for extrapolating to very asymmetric
nuclei and the impact of such extrapolations on the predictions of isotopic
observables in multifragmentation. We obtain improved mass predictions by
incorporating measured masses and extrapolating to unmeasured masses with a
mass formula that includes surface symmetry and Coulomb terms. We find that
using accurate masses has a significant impact on the predicted isotopic
observables.Comment: 12 pages, 4 figure
B_s --> mu+ mu- decay in the R-parity violating minimal supergravity
We study B_s --> mu+ mu- in the context of the R-parity violating minimal
supergravity in the high tan beta regime. We find that the lowest value of the
branching ratio can go well below the present LHCb sensitivity and hence B_s
--> mu+ mu- can even be invisible to the LHC. We also find that the present
upper bound on Br(B_s --> mu+ mu-) puts strong constraint on the minimal
supergravity parameter space. The constraints become more severe if the upper
bound is close to its standard model prediction.Comment: 18 pages, 10 figures; version to be published in European Physical
Journal
Probing New Physics Models of Neutrinoless Double Beta Decay with SuperNEMO
The possibility to probe new physics scenarios of light Majorana neutrino
exchange and right-handed currents at the planned next generation neutrinoless
double beta decay experiment SuperNEMO is discussed. Its ability to study
different isotopes and track the outgoing electrons provides the means to
discriminate different underlying mechanisms for the neutrinoless double beta
decay by measuring the decay half-life and the electron angular and energy
distributions.Comment: 17 pages, 14 figures, to be published in E.P.J.
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Mediated intimacy and postfeminism: A discourse analytic examination of sex and relationships advice in a women's magazine
This paper uses a discourse analytic perspective to analyse sex and relationship advice in a best-selling women's magazine. It identifies three different interpretative repertoires which together structure constructions of sexual relationships: the intimate entrepreneurship repertoire, organised around plans, goals and the scientific management of relationships; men-ology, in which women are instructed in how to learn to please men; and transforming the self, which calls on women to remodel their interior lives in order to construct a desirable subjectivity. The paper considers each repertoire in turn, and also looks at how they work together in order to privilege men and heterosexuality. Discussion focuses in particular on the postfeminist nature of the advice, in which pre-feminist, feminist and anti-feminist ideas are entangled in such a way as to make gender ideologies more pernicious and difficult to contest
A genome-wide association study of obstructive heart defects among participants in the National Birth Defects Prevention Study
Obstructive heart defects (OHDs) share common structural lesions in arteries and cardiac valves, accounting for ~25% of all congenital heart defects. OHDs are highly heritable, resulting from interplay among maternal exposures, genetic susceptibilities, and epigenetic phenomena. A genome-wide association study was conducted in National Birth Defects Prevention Study participants (Ndiscovery = 3978; Nreplication = 2507), investigating the genetic architecture of OHDs using transmission/disequilibrium tests (TDT) in complete case-parental trios (Ndiscovery_TDT = 440; Nreplication_TDT = 275) and case–control analyses separately in infants (Ndiscovery_CCI = 1635; Nreplication_CCI = 990) and mothers (case status defined by infant; Ndiscovery_CCM = 1703; Nreplication_CCM = 1078). In the TDT analysis, the SLC44A2 single nucleotide polymorphism (SNP) rs2360743 was significantly associated with OHD (pdiscovery = 4.08 × 10−9; preplication = 2.44 × 10−4). A CAPN11 SNP (rs55877192) was suggestively associated with OHD (pdiscovery = 1.61 × 10−7; preplication = 0.0016). Two other SNPs were suggestively associated (p < 1 × 10−6) with OHD in only the discovery sample. In the case–control analyses, no SNPs were genome-wide significant, and, even with relaxed thresholds (× discovery < 1 × 10−5 and preplication < 0.05), only one SNP (rs188255766) in the infant analysis was associated with OHDs (pdiscovery = 1.42 × 10−6; preplication = 0.04). Additional SNPs with pdiscovery < 1 × 10−5 were in loci supporting previous findings but did not replicate. Overall, there was modest evidence of an association between rs2360743 and rs55877192 and OHD and some evidence validating previously published findings
Search for R-parity Violating Decays of Supersymmetric Particles in e+e- Collisions at LEP
A search, in e^+e^- collisions, for chargino, neutralino, scalar lepton and
scalar quark pair-production is performed, without assuming R-parity
conservation in decays, in the case that only one of the coupling constants
lambda_ijk or lambda''_ijk is non-negligible. No signal is found in data up to
a centre-of-mass energy of 208GeV. Limits on the production cross sections and
on the masses of supersymmetric particles are derived
Phylogenomic analysis of a 55.1 kb 19-gene dataset resolves a monophyletic Fusarium that includes the Fusarium solani Species Complex
Scientific communication is facilitated by a data-driven, scientifically sound taxonomy that considers the end-user¿s needs and established successful practice. In 2013, the Fusarium community voiced near unanimous support for a concept of Fusarium that represented a clade comprising all agriculturally and clinically important Fusarium species, including the F. solani species complex (FSSC). Subsequently, this concept was challenged in 2015 by one research group who proposed dividing the genus Fusarium into seven genera, including the FSSC described as members of the genus Neocosmospora, with subsequent justification in 2018 based on claims that the 2013 concept of Fusarium is polyphyletic. Here, we test this claim and provide a phylogeny based on exonic nucleotide sequences of 19 orthologous protein-coding genes that strongly support the monophyly of Fusarium including the FSSC. We reassert the practical and scientific argument in support of a genus Fusarium that includes the FSSC and several other basal lineages, consistent with the longstanding use of this name among plant pathologists, medical mycologists, quarantine officials, regulatory agencies, students, and researchers with a stake in its taxonomy. In recognition of this monophyly, 40 species described as genus Neocosmospora were recombined in genus Fusarium, and nine others were renamed Fusarium. Here the global Fusarium community voices strong support for the inclusion of the FSSC in Fusarium, as it remains the best scientific, nomenclatural, and practical taxonomic option availabl
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