330 research outputs found
Distances from the Correlation between Galaxy Luminosities and Rotation Rates
A large luminosity--linewidth template sample is now available, improved
absorption corrections have been derived, and there are a statistically
significant number of galaxies with well determined distances to supply the
zero point. A revised estimate of the Hubble Constant is H_0=77 +-4 km/s/Mpc
where the error is the 95% probability statistical error. Systematic
uncertainties are potentially twice as large.Comment: 21 pages, 9 figures. Invited chapter for the book `Post-Hipparcos
Cosmic Candles', Eds. F. Caputo and A. Heck (Kluwer Academic Publishers,
Dordrecht
Phenomenological Consequences of sub-leading Terms in See-Saw Formulas
Several aspects of next-to-leading (NLO) order corrections to see-saw
formulas are discussed and phenomenologically relevant situations are
identified. We generalize the formalism to calculate the NLO terms developed
for the type I see-saw to variants like the inverse, double or linear see-saw,
i.e., to cases in which more than two mass scales are present. In the standard
type I case with very heavy fermion singlets the sub-leading terms are
negligible. However, effects in the percent regime are possible when
sub-matrices of the complete neutral fermion mass matrix obey a moderate
hierarchy, e.g. weak scale and TeV scale. Examples are cancellations of large
terms leading to small neutrino masses, or inverse see-saw scenarios. We
furthermore identify situations in which no NLO corrections to certain
observables arise, namely for mu-tau symmetry and cases with a vanishing
neutrino mass. Finally, we emphasize that the unavoidable unitarity violation
in see-saw scenarios with extra fermions can be calculated with the formalism
in a straightforward manner.Comment: 22 pages, matches published versio
Probing top charged-Higgs production using top polarization at the Large Hadron Collider
We study single top production in association with a charged Higgs in the
type II two Higgs doublet model at the Large Hadron Collider. The polarization
of the top, reflected in the angular distributions of its decay products, can
be a sensitive probe of new physics in its production. We present theoretically
expected polarizations of the top for top charged-Higgs production, which is
significantly different from that in the closely related process of t-W
production in the Standard Model. We then show that an azimuthal symmetry,
constructed from the decay lepton angular distribution in the laboratory frame,
is a sensitive probe of top polarization and can be used to constrain
parameters involved in top charged-Higgs production.Comment: 22 pages, 18 Figures, Discussions about backgrounds and NLO
corrections added, figures modified, references added, Version published in
JHE
Decoupling property of the supersymmetric Higgs sector with four doublets
In supersymmetric standard models with multi Higgs doublet fields,
selfcoupling constants in the Higgs potential come only from the D-terms at the
tree level. We investigate the decoupling property of additional two heavier
Higgs doublet fields in the supersymmetric standard model with four Higgs
doublets. In particular, we study how they can modify the predictions on the
quantities well predicted in the minimal supersymmetric standard model (MSSM),
when the extra doublet fields are rather heavy to be measured at collider
experiments. The B-term mixing between these extra heavy Higgs bosons and the
relatively light MSSM-like Higgs bosons can significantly change the
predictions in the MSSM such as on the masses of MSSM-like Higgs bosons as well
as the mixing angle for the two light CP-even scalar states. We first give
formulae for deviations in the observables of the MSSM in the decoupling region
for the extra two doublet fields. We then examine possible deviations in the
Higgs sector numerically, and discuss their phenomenological implications.Comment: 26 pages, 24 figures, text sligtly modified,version to appear in
Journal of High Energy Physic
Phenomenology and Cosmology of an Electroweak Pseudo-Dilaton and Electroweak Baryons
In many strongly-interacting models of electroweak symmetry breaking the
lowest-lying observable particle is a pseudo-Goldstone boson of approximate
scale symmetry, the pseudo-dilaton. Its interactions with Standard Model
particles can be described using a low-energy effective nonlinear chiral
Lagrangian supplemented by terms that restore approximate scale symmetry,
yielding couplings of the pseudo-dilaton that differ from those of a Standard
Model Higgs boson by fixed factors. We review the experimental constraints on
such a pseudo-dilaton in light of new data from the LHC and elsewhere. The
effective nonlinear chiral Lagrangian has Skyrmion solutions that may be
identified with the `electroweak baryons' of the underlying
strongly-interacting theory, whose nature may be revealed by the properties of
the Skyrmions. We discuss the finite-temperature electroweak phase transition
in the low-energy effective theory, finding that the possibility of a
first-order electroweak phase transition is resurrected. We discuss the
evolution of the Universe during this transition and derive an
order-of-magnitude lower limit on the abundance of electroweak baryons in the
absence of a cosmological asymmetry, which suggests that such an asymmetry
would be necessary if the electroweak baryons are to provide the cosmological
density of dark matter. We revisit estimates of the corresponding
spin-independent dark matter scattering cross section, with a view to direct
detection experiments.Comment: 34 pages, 4 figures, additional references adde
Non-standard interactions versus non-unitary lepton flavor mixing at a neutrino factory
The impact of heavy mediators on neutrino oscillations is typically described
by non-standard four-fermion interactions (NSIs) or non-unitarity (NU). We
focus on leptonic dimension-six effective operators which do not produce
charged lepton flavor violation. These operators lead to particular
correlations among neutrino production, propagation, and detection non-standard
effects. We point out that these NSIs and NU phenomenologically lead, in fact,
to very similar effects for a neutrino factory, for completely different
fundamental reasons. We discuss how the parameters and probabilities are
related in this case, and compare the sensitivities. We demonstrate that the
NSIs and NU can, in principle, be distinguished for large enough effects at the
example of non-standard effects in the --sector, which basically
corresponds to differentiating between scalars and fermions as heavy mediators
as leading order effect. However, we find that a near detector at superbeams
could provide very synergistic information, since the correlation between
source and matter NSIs is broken for hadronic neutrino production, while NU is
a fundamental effect present at any experiment.Comment: 32 pages, 5 figures. Final version published in JHEP. v3: Typo in Eq.
(27) correcte
Snoring in primary school children and domestic environment: A Perth school based study
BACKGROUND: The home is the predominant environment for exposure to many environmental irritants such as air pollutants and allergens. Exposure to common indoor irritants including volatile organic compounds, formaldehyde and nitrogen dioxide, may increase the risk of snoring for children. The aim of this study was to investigate domestic environmental factors associated with snoring in children. METHODS: A school-based respiratory survey was administered during March and April of 2002. Nine hundred and ninety six children from four primary schools within the Perth metropolitan area were recruited for the study. A sub-group of 88 children aged 4–6 years were further selected from this sample for domestic air pollutant assessment. RESULTS: The prevalences of infrequent snoring and habitual snoring in primary school children were 24.9% and 15.2% respectively. Passive smoking was found to be a significant risk factor for habitual snoring (odds ratio (OR) = 1.77; 95% confidence interval (CI): 1.20–2.61), while having pets at home appeared to be protective against habitual snoring (OR = 0.58; 95% CI: 0.37–0.92). Domestic pollutant assessments showed that the prevalence of snoring was significantly associated with exposure to nitrogen dioxide during winter. Relative to the low exposure category (<30 μg/m(3)), the adjusted ORs of snoring by children with medium (30 – 60 μg/m(3)) and high exposures (> 60 μg/m(3)) to NO(2 )were 2.5 (95% CI: 0.7–8.7) and 4.5 (95% CI: 1.4–14.3) respectively. The corresponding linear dose-response trend was also significant (P = 0.011). CONCLUSION: Snoring is common in primary school children. Domestic environments may play a significant role in the increased prevalence of snoring. Exposure to nitrogen dioxide in domestic environment is associated with snoring in children
Impacto da técnica de expiração lenta e prolongada na mecânica respiratória de lactentes sibilantes
Global analysis of gene expression in mineralizing fish vertebra-derived cell lines: new insights into anti-mineralogenic effect of vanadate
<p>Abstract</p> <p>Background</p> <p>Fish has been deemed suitable to study the complex mechanisms of vertebrate skeletogenesis and gilthead seabream (<it>Sparus aurata</it>), a marine teleost with acellular bone, has been successfully used in recent years to study the function and regulation of bone and cartilage related genes during development and in adult animals. Tools recently developed for gilthead seabream, <it>e.g. </it>mineralogenic cell lines and a 4 Ă— 44K Agilent oligo-array, were used to identify molecular determinants of <it>in vitro </it>mineralization and genes involved in anti-mineralogenic action of vanadate.</p> <p>Results</p> <p>Global analysis of gene expression identified 4,223 and 4,147 genes differentially expressed (fold change - FC > 1.5) during <it>in vitro </it>mineralization of VSa13 (pre-chondrocyte) and VSa16 (pre-osteoblast) cells, respectively. Comparative analysis indicated that nearly 45% of these genes are common to both cell lines and gene ontology (GO) classification is also similar for both cell types. Up-regulated genes (FC > 10) were mainly associated with transport, matrix/membrane, metabolism and signaling, while down-regulated genes were mainly associated with metabolism, calcium binding, transport and signaling. Analysis of gene expression in proliferative and mineralizing cells exposed to vanadate revealed 1,779 and 1,136 differentially expressed genes, respectively. Of these genes, 67 exhibited reverse patterns of expression upon vanadate treatment during proliferation or mineralization.</p> <p>Conclusions</p> <p>Comparative analysis of expression data from fish and data available in the literature for mammalian cell systems (bone-derived cells undergoing differentiation) indicate that the same type of genes, and in some cases the same orthologs, are involved in mechanisms of <it>in vitro </it>mineralization, suggesting their conservation throughout vertebrate evolution and across cell types. Array technology also allowed identification of genes differentially expressed upon exposure of fish cell lines to vanadate and likely involved in its anti-mineralogenic activity. Many were found to be unknown or they were never associated to bone homeostasis previously, thus providing a set of potential candidates whose study will likely bring insights into the complex mechanisms of tissue mineralization and bone formation.</p
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