13,283 research outputs found
Proton lifetime, Yukawa couplings and dynamical SUSY breaking in SU(5) GUT
We study the influence of messenger Yukawa couplings and top, bottom and
Yukawa couplings on the proton lifetime in SU(5) Supersymmetric GUT with
dynamical supersymmetry breaking mechanism due to Dine and Nelson.Comment: 7 pages latex file, 6 ps figures include
Probiotic administration in congenital heart disease: a pilot study.
ObjectiveTo investigate the impact of probiotic Bifidobacterium longum ssp. infantis on the fecal microbiota and plasma cytokines in neonates with congenital heart disease.Study designSixteen infants with congenital heart disease were randomly assigned to receive either B. infantis (4.2 × 10(9) colony-forming units two times daily) or placebo for 8 weeks. Stool specimens from enrolled infants and from six term infants without heart disease were analyzed for microbial composition. Plasma cytokines were analyzed weekly in the infants with heart disease.ResultsHealthy control infants had increased total bacteria, total Bacteroidetes and total bifidobacteria compared to the infants with heart disease, but there were no significant differences between the placebo and probiotic groups. Plasma interleukin (IL)10, interferon (IFN)γ and IL1β levels were transiently higher in the probiotic group.ConclusionCongenital heart disease in infants is associated with dysbiosis. Probiotic B. infantis did not significantly alter the fecal microbiota. Alterations in plasma cytokines were found to be inconsistent
Black string corrections in variable tension braneworld scenarios
Braneworld models with variable tension are investigated, and the corrections
on the black string horizon along the extra dimension are provided. Such
corrections are encrypted in additional terms involving the covariant
derivatives of the variable tension on the brane, providing profound
consequences concerning the black string horizon variation along the extra
dimension, near the brane. The black string horizon behavior is shown to be
drastically modified by the terms corrected by the brane variable tension. In
particular, a model motivated by the phenomenological interesting case
regarding Eotvos branes is investigated. It forthwith provides further physical
features regarding variable tension braneworld scenarios, heretofore concealed
in all previous analysis in the literature. All precedent analysis considered
uniquely the expansion of the metric up to the second order along the extra
dimension, what is able to evince solely the brane variable tension absolute
value. Notwithstanding, the expansion terms aftermath, further accomplished in
this paper from the third order on, elicits the successive covariant
derivatives of the brane variable tension, and their respective coupling with
the extrinsic curvature, the Weyl tensor, and the Riemann and Ricci tensors, as
well as the scalar curvature. Such additional terms are shown to provide sudden
modifications in the black string horizon in a variable tension braneworld
scenarioComment: 12 pages, 5 figures, accepted in PR
First results with the ORPHEUS dark matter detector
The ORPHEUS dark matter detector is operating at our underground laboratory
in Bern (70 m.w.e.). The detector relies on measuring the magnetic flux
variation produced by weakly interacting massive particles (WIMPs) as they heat
micron-sized superheated superconducting tin granules (SSG) and induce
superconducting-to-normal phase transitions. In an initial phase, 0.45 kg of
tin granules in a segmented detector volume have been used. In this paper a
general description of the experimental set-up, overall performance of the
detector, and first results are presented.Comment: 20 pages, Latex, submitted to Astropart. Phy
Lexicographic cones and the ordered projective tensor product
We introduce lexicographic cones, a method of assigning an ordered vector
space \Lex(S) to a poset , generalising the standard lexicographic cone.
These lexicographic cones are then used to prove that the projective tensor
cone of two arbitrary cones is a cone, and to find a new characterisation of
finite-dimensional vector lattices.Comment: 8 page
NNLO Logarithmic Expansions and Exact Solutions of the DGLAP Equations from x-Space: New Algorithms for Precision Studies at the LHC
A NNLO analysis of certain logarithmic expansions, developed for precision
studies of the evolution of the QCD parton distributions (pdf) at the Large
Hadron Collider, is presented. We elaborate on their relations to all the
solutions of the DGLAP equations that have been hitherto obtained from Mellin
space, to which are equivalent. Exact expansions, equivalent to exact solutions
of the equations, are constructed in the non-singlet sector. The algorithmic
features of our approach are also emphasized, since this method allows to
obtain numerical solutions of the evolution equations with the same accuracy of
other methods, based on Mellin space, and of brute force methods, which solve
the equations by finite differences. The implementation of our analysis allows
to compare with existing benchmarks for the evolution of the pdf's, useful for
applications at the LHC, and to extend them significantly in a systematic
fashion, especially when solutions that retain logarithmic corrections only of
a certain accuracy are searched for.Comment: 56 pages, no figure
A Renormalizable Supersymmetric SU(5) Model
In the Supersymmetric SU(5) Model of Unification with the Missing Partner
Mechanism, we present a renormalizable model using the Georgi-Jarlsog mechanism
to describe the fermion masses and mixing. At the meantime the proton decay
rates are also suppressed to satisfy the experimental data
Beyond self-report: tools to compare estimated and real-world smartphone use
Psychologists typically rely on self-report data when quantifying mobile phone usage, despite little evidence of its validity. In this paper we explore the accuracy of using self-reported estimates when compared with actual smartphone use. We also include source code to process and visualise these data. We compared 23 participants' actual smartphone
use over a two-week period with self-reported estimates and the Mobile Phone Problem Use Scale. Our results indicate that estimated time spent using a smartphone may be an adequate measure of use, unless a greater resolution of data are required. Estimates concerning the number of times an individual used their phone across a typical day did not correlate with actual smartphone use. Neither estimated duration nor number of uses correlated with the Mobile Phone Problem Use Scale. We conclude that estimated smartphone use should be interpreted with caution in psychological research
Ramsey interference in a multilevel quantum system
We report Ramsey interference in the excitonic population of a negatively charged quantum dot measured in resonant fluorescence. Our experiments show that the decay time of the Ramsey interference is limited by the spectral width of the transition. Applying a vertical magnetic field induces Zeeman split transitions that can be addressed by changing the laser detuning to reveal two-, three-, and four-level system behavior. We show that under finite field the phase-sensitive control of two optical pulses from a single laser can be used to prepare both population and spin states simultaneously. We also demonstrate the coherent optical manipulation of a trapped spin in a quantum dot in a Faraday geometry magnetic field
Phantom Friedmann Cosmologies and Higher-Order Characteristics of Expansion
We discuss a more general class of phantom () cosmologies with
various forms of both phantom () matter. We
show that many types of evolution which include both Big-Bang and Big-Rip
singularities are admitted and give explicit examples. Among some interesting
models, there exist non-singular oscillating (or "bounce") cosmologies, which
appear due to a competition between positive and negative pressure of variety
of matter content. From the point of view of the current observations the most
interesting cosmologies are the ones which start with a Big-Bang and terminate
at a Big-Rip. A related consequence of having a possibility of two types of
singularities is that there exists an unstable static universe approached by
the two asymptotic models - one of them reaches Big-Bang, and another reaches
Big-Rip. We also give explicit relations between density parameters
and the dynamical characteristics for these generalized phantom models,
including higher-order observational characteristics such as jerk and "kerk".
Finally, we discuss the observational quantities such as luminosity distance,
angular diameter, and source counts, both in series expansion and explicitly,
for phantom models. Our series expansion formulas for the luminosity distance
and the apparent magnitude go as far as to the fourth-order in redshift
term, which includes explicitly not only the jerk, but also the "kerk" (or
"snap") which may serve as an indicator of the curvature of the universe.Comment: REVTEX 4, 23 pages, references updated, to appear in Annals of
Physics (N.Y.
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