144 research outputs found
Model for a Universe described by a non-minimally coupled scalar field and interacting dark matter
In this work it is investigated the evolution of a Universe where a scalar
field, non-minimally coupled to space-time curvature, plays the role of
quintessence and drives the Universe to a present accelerated expansion. A
non-relativistic dark matter constituent that interacts directly with dark
energy is also considered, where the dark matter particle mass is assumed to be
proportional to the value of the scalar field. Two models for dark matter
pressure are considered: the usual one, pressureless, and another that comes
from a thermodynamic theory and relates the pressure with the coupling between
the scalar field and the curvature scalar. Although the model has a strong
dependence on the initial conditions, it is shown that the mixture consisted of
dark components plus baryonic matter and radiation can reproduce the expected
red-shift behavior of the deceleration parameter, density parameters and
luminosity distance.Comment: 11 pages and 6 figures. To appear in GR
Brown muscle disease and Manila clam Ruditapes Philippinarum dynamics in Arcachon Bay, France
Brown Muscle Disease (BMD) affects Manila clam Ruditapes philippinarum. It was described for the first time in 2005 in Arcachon Bay, France. The pathology consists in a progressive necrosis of the posterior adductor muscle, valve gaping, clam migration to the sediment surface, and death. This study aims to quantify the prevalence of BMD in the bay and to evaluate the effect of BMD on Manila clam dynamics. The prevalence was assessed on 50 stations spread within Arcachon Bay. About 62% of Manila clam habitat surface was infected by BMD. A survey of buried and surface clams was conducted from November 2006 to March 2008 in Lanton, a site infected by BMD. Modal progression analysis separated confidently cohorts from 2003 to 2005 recruitments. This pathology only affected adult clams (>25 mm, >2 years). For both buried and surface individuals, shell length was significantly correlated with BMD infection. Surface clams had prevalence (67%) higher than buried clams (23%) and showed greater mortality rate after 15 d in running water: 82% against 12% for buried individuals. The final disease index (FDI) and the condition index (CI) were monthly evaluated on 50 clams located at each position in the sediment. CI displayed a significant decrease after BMD's infection from light to severe disease stages. Length data analysis through Bhattacharya's method (FISAT II software) allowed identifying four cohorts. The 2003s cohort enabled to calculate mortality rate that was 39% for 5 months and to estimate that BMD was responsible of 95% of that mortality. The temperature was certainly an important factor in BMD transmission, because cohort dynamics results argued that BMD developed during spring and summer
The Interplay Between the "Low" and "High" Energy CP-Violation in Leptogenesis
We analyse within the "flavoured" leptogenesis scenario of baryon asymmetry
generation, the interplay of the "low energy" CP-violation, originating from
the PMNS neutrino mixing matrix , and the "high energy" CP-violation which
can be present in the matrix of neutrino Yukawa couplings, , and can
manifest itself only in "high" energy scale processes. The type I see-saw model
with three heavy right-handed Majorana neutrinos having hierarchical spectrum
is considered. The "orthogonal" parametrisation of the matrix of neutrino
Yukawa couplings, which involves a complex orthogonal matrix , is employed.
In this approach the matrix is the source of "high energy" CP-violation.
Results for normal hierarchical (NH) and inverted hierarchical (IH) light
neutrino mass spectrum are derived in the case of decoupling of the heaviest RH
Majorana neutrino. It is shown that taking into account the contribution to
due to the CP-violating phases in the neutrino mixing matrix can
change drastically the predictions for , obtained assuming only "high
energy" CP-violation from the -matrix is operative in leptogenesis. In the
case of IH spectrum, in particular, there exist significant regions in the
corresponding parameter space where the purely "high energy" contribution in
plays a subdominant role in the production of baryon asymmetry compatible
with the observations.Comment: Results unchanged; comments and references added; version to be
puplished in Eur.Phys.J.
Lepton Flavor Violating Process in Bi-maximal texture of Neutrino Mixings
We investigate the lepton flavor violation in the framework of the MSSM with
right-handed neutrinos taking the large mixing angle MSW solution in the
quasi-degenerate and the inverse-hierarchical neutrino masses. We predict the
branching ratio of and processes
assuming the degenerate right-handed Majorana neutrino masses. We find that the
branching ratio in the quasi-degenerate neutrino mass spectrum is 100 times
smaller than the ones in the inverse-hierarchical and the hierarchical neutrino
spectra. We emphasize that the magnitude of is one of important
ingredients to predict BR(). The effect of the deviation
from the complete-degenerate right-handed Majorana neutrino masses are also
estimated. Furtheremore, we examine the S_{3\sL}\times S_{3\sR} model, which
gives the quasi-degenerate neutrino masses, and the Shafi-Tavartkiladze model,
which gives the inverse-hierarchical neutrino masses. Both predicted branching
ratios of are smaller than the experimantal bound.Comment: Latex file, 38 pages, 10 figures, revised versio
Collisionless collective modes of fermions in magnetic traps
We present a Random-Phase-Approximation formalism for the collective spectrum
of two hyperfine species of dilute 40K atoms, magnetically trapped at zero
temperature and subjected to a repulsive s-wave interaction between atoms with
different spin projections. We examine the density-like and the spin-like
oscillation spectra, as well as the transition density profiles created by
external multipolar fields. The zero sound spectrum is always fragmented and
the density and spin channels become clearly distinguishable if the trapping
potentials acting on the species are identical. Although this distinction is
lost when these confining fields are different, at selected excitation
frequencies the transition densities may display the signature of the channel.Comment: 10 pages, 9 figure
Supersymmetric Seesaw without Singlet Neutrinos: Neutrino Masses and Lepton-Flavour Violation
We consider the supersymmetric seesaw mechanism induced by the exchange of
heavy SU(2)_W triplet states, rather than `right-handed' neutrino singlets, to
generate neutrino masses. We show that in this scenario the neutrino flavour
structure tested at low-energy in the atmospheric and solar neutrino
experiments is directly inherited from the neutrino Yukawa couplings to the
triplets. This allows us to predict the ratio of the tau --> mu gamma (or tau
--> e gamma) and mu --> e gamma decay rates in terms of the low-energy neutrino
parameters. Moreover, once the model is embedded in a grand unified model,
quark-flavour violation can be linked to lepton-flavour violation.Comment: 26 LaTeX pages, 10 postscript figures, uses epsfig and axodraw.
Comments and references adde
The role of Majorana CP phases in the bi-maximal mixing scheme -hierarchical Dirac mass case-
We discuss the energy scale profile of the bi-maximal mixing which is given
at the GUT energy scale in the minimal SUSY model, associated with an
assumption that Y_nu^dagger Y_nu is diagonal, where Y_nu is the neutrino-Yukawa
coupling matrix. In this model, the Dirac mass matrix which appears in the
seesaw neutrino mass matrix is determined by three neutrino masses, two
relative Majorana phases and three heavy Majorana masses. All CP phases are
related by two Majorana phases. We show that the requirement that the solar
mixing angle moves from the maximal mixing at GUT to the observed one as the
energy scale decreases by the renormalization effect. We discuss the
leptogenesis, and the lepton flavor violation process by assuming the universal
soft breaking terms.Comment: 19 pages, 2 figure
Charged lepton Flavor Violation in Supersymmetry with Bilinear R-Parity Violation
The simplest unified extension of the Minimal Supersymmetric Standard Model
with bi-linear R-parity violation naturally predicts a hierarchical neutrino
mass spectrum, suitable to explain atmospheric and solar neutrino fluxes. We
study whether the individual violation of the lepton numbers L_{e,mu,tau} in
the charged sector can lead to measurable rates for BR(mu->e gamma)and
$BR(tau-> mu gamma). We find that some of the R-parity violating terms that are
compatible with the observed atmospheric neutrino oscillations could lead to
rates for mu->e gamma measurable in projected experiments. However, the Delta
m^2_{12} obtained for those parameters is too high to be compatible with the
solar neutrino data, excluding therefore the possibility of having measurable
rates for mu->e gamma in the model.Comment: 29 pages, 8 figures. Constraint from solar neutrino data included,
conclusions changed respect v
Famosa: Evaluation of a multigene panel in patients with suspected HBOC
Background: Objectives: Characterize 1) the frequency of mutations in patients with clinical criteria for HBOC using a 25-gene panel in a Spanish population (FAMOSA study). 2) The psychological impact of these tests and patient''s counseling preferences.
Methods: Patients with breast or ovarian cancer who met the NCCN criteria for genetic testing with a) prior testing for BRCA genes with NO mutation identified; or b) recently diagnosed (<6 months) and not genetically tested, were enrolled for multiplex cancer testing (MyRisk 25-gene panel). Participants completed self-questionnaires regarding geneting counseling preferences and three psychological scales (MICRA, CWS, R-IES) at base-line, one week, three and twelve months after results disclosure.
Results: From November 14 to February 15, 210 patients were included in the FAMOSA study (109 HBOC). 61 (56%) patients were previously tested for BRCA1/2 gene mutations with conventional techniques; median age: 44y (22-77); gender: 3 males / 106 females; cancer types: breast 95 (87%); ovary 14 (13%). Overall 22 pathogenic variants were identified in 21 patients (19, 3%): 10 BRCA1, 2 BRCA2, 2 PALB2, 3 MUYTH, 1 CDKN2A; 2 ATM, 1 BRAD1, 1 BRIP1. One patient had an unexpected mutation in CDKN2A gene (gluteus sarcoma age 20; bilateral breast ca; ages 45 and 50; father lung ca, age 70; brother melanoma, age 35). Three patients had a significant mutation of a recessive condition in MUYTH. Of 61 patients previously tested negative for HBOC, 1 had a pathogenic variant in BRCA1 and 17/ 19 patients with VUS were classified negative in BRCA genes with MyRisk.Patients are willing to be disclosed all available information from panel testing. Differences were observed among type of results at short and mid-term. Cancer worry was higher in moderate-penetrance carriers than high penetrance carriers. Longer follow up is ongoing.
Conclusions: Panel testing in patients with HBOC yielded a 19, 3% mutation rate, increasing the yield of genetic mutations beyond BRCA. Patients are willing to be disclosed all available information from panel testing
The Problem of Large Leptonic Mixing
Unlike in the quark sector where simple permutation symmetries can
generate the general features of quark masses and mixings, we find it
impossible (under conditions of hierarchy for the charged leptons and without
considering the see-saw mechanism or a more elaborate extension of the SM) to
guarantee large leptonic mixing angles with any general symmetry or
transformation of only known particles. If such symmetries exist, they must be
realized in more extended scenarios.Comment: RevTeX, 4 pages, no figure
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