679 research outputs found
Generalized Galilean Algebras and Newtonian Gravity
The non-relativistic versions of the generalized Poincar\'{e} algebras and
generalized -Lorentz algebras are obtained. This non-relativistic algebras
are called, generalized Galilean algebras type I and type II and denoted by
and
respectively. Using a generalized In\"{o}n\"{u}--Wigner contraction procedure
we find that the generalized Galilean algebras type I can be obtained from the
generalized Galilean algebras type II. The -expansion procedure allows us to
find the algebra from the Newton--Hooke
algebra with central extension. The procedure developed in Ref. \cite{newton}
allow us to show that the non-relativistic limit of the five dimensional
Einstein--Chern--Simons gravity is given by a modified version of the Poisson
equation. The modification could be compatible with the effects of Dark Matter,
which leads us to think that Dark Matter can be interpreted as a
non-relativistic limit of Dark Energy.Comment: 16 pages, no figures in 755 (2016) 433-43
Gaussian covariance matrices for anisotropic galaxy clustering measurements
Measurements of the redshift-space galaxy clustering have been a prolific
source of cosmological information in recent years. Accurate covariance
estimates are an essential step for the validation of galaxy clustering models
of the redshift-space two-point statistics. Usually, only a limited set of
accurate N-body simulations is available. Thus, assessing the data covariance
is not possible or only leads to a noisy estimate. Further, relying on
simulated realisations of the survey data means that tests of the cosmology
dependence of the covariance are expensive. With these points in mind, this
work presents a simple theoretical model for the linear covariance of
anisotropic galaxy clustering observations with synthetic catalogues.
Considering the Legendre moments (`multipoles') of the two-point statistics and
projections into wide bins of the line-of-sight parameter (`clustering
wedges'), we describe the modelling of the covariance for these anisotropic
clustering measurements for galaxy samples with a trivial geometry in the case
of a Gaussian approximation of the clustering likelihood. As main result of
this paper, we give the explicit formulae for Fourier and configuration space
covariance matrices. To validate our model, we create synthetic HOD galaxy
catalogues by populating the haloes of an ensemble of large-volume N-body
simulations. Using linear and non-linear input power spectra, we find very good
agreement between the model predictions and the measurements on the synthetic
catalogues in the quasi-linear regime.Comment: 17 pages, 16 figures, 3 tables; modified to match version accepted by
MNRA
Probing neutralino dark matter in the MSSM & the NMSSM with directional detection
We investigate the capability of directional detectors to probe neutralino
dark matter in the Minimal Supersymmetric Standard Model and the
Next-to-Minimal Supersymmetric Standard Model with parameters defined at the
weak scale. We show that directional detectors such as the future MIMAC
detector will probe spin dependent dark matter scattering on nucleons that are
beyond the reach of current spin independent detectors. The complementarity
between indirect searches, in particular using gamma rays from dwarf spheroidal
galaxies, spin dependent and spin independent direct search techniques is
emphasized. We comment on the impact of the negative results on squark searches
at the LHC. Finally, we investigate how the fundamental parameters of the
models can be constrained in the event of a dark matter signal.Comment: 21 pages, 16 figure
Anatomy of flower and fruit of Vassobia breviflora (Solanaceae) in the south of the southern Yungas (Argentina)
Solanaceae es una familia con aproximadamente 2400 especies de distribución cosmopolita. Vassobia breviflora es la única especie del género presente en Argentina. El objetivo de este trabajo fue revisar y caracterizar la anatomía de la flor y fruto de V. breviflora a partir de muestras recolectadas en poblaciones de las Yungas del noroeste argentino. Se aplicaron técnicas anatómicas convencionales. Los resultados mostraron que la mayoría de las estructuras de la flor, el fruto y la semilla no difirieron de lo previamente reportado respecto de la organización estructural descripta para otras especies de Solanaceae. No obstante, por primera vez, describimos el androceo, el fruto, la semilla, pedicelo floral y frutal, cinco tipos de tricomas y cinco tipos de estomas en el perianto. Encontramos diferencias en la forma del tejido de transmisión y del tipo de óvulo respecto de lo previamente descripto. Además, localizamos el parénquima y las células epidérmicas secretoras del nectario. En el contexto de la familia Solanaceae, discutimos la función y valor diagnóstico de las estructuras descriptas.Solanaceae is a family with nearly 2400 species of cosmopolitan distribution. Vassobia breviflora is the only species of the genus present in Argentina. The goal of this work was to review and characterize the anatomy of the flower and fruit of V. breviflora from samples collected in populations of Yungas in the argentine Northwest. Conventional anatomical techniques were applied. The results showed that most flower, fruit and seed structures did not differ from those previously reported regarding the structural organization described for other species of the Solanaceae family. However, for the first time, we described the androecium, fruit, seed, floral and fruit pedicels, five types of tricomes and five types of stomata in the perianth. We found some differences in the shape of the transmission tissue and in the type of ovule with respect to that previously reported. Also, we located the parenchyma and the epidermic secretory cells of the nectary. In the context of the family Solanaceae, we discussed the function and diagnostic value of the described structures.Fil: Bernacki, F. G.. Fundación Miguel Lillo; ArgentinaFil: Albornoz, P. L.. Fundación Miguel Lillo; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo; ArgentinaFil: Valoy, M.. Fundación Miguel Lillo; ArgentinaFil: Ordano, Mariano Andrés. Fundación Miguel Lillo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
The Higgs boson in the MSSM in light of the LHC
We investigate the expectations for the light Higgs signal in the MSSM in
different search channels at the LHC. After taking into account dark matter and
flavor constraints in the MSSM with eleven free parameters, we show that the
light Higgs signal in the channel is expected to be at most at
the level of the SM Higgs, while the from W fusion
and/or the can be enhanced. For the main discovery
mode, we show that a strong suppression of the signal occurs in two different
cases: low or large invisible width. A more modest suppression is
associated with the effect of light supersymmetric particles. Looking for such
modification of the Higgs properties and searching for supersymmetric partners
and pseudoscalar Higgs offer two complementary probes of supersymmetry.Comment: 19 pages, 8 figure
Congenital Transmission of Trypanosoma cruzi: A Review About the Interactions Between the Parasite, the Placenta, the Maternal and the Fetal/Neonatal Immune Responses
Chagas disease (CD), caused by the protozoan parasite Trypanosoma cruzi, is
considered a neglected tropical disease by the World Health Organization. Congenital
transmission of CD is an increasingly relevant public health problem. It progressively
becomes the main transmission route over others and can occur in both endemic and
non-endemic countries. Though most congenitally infected newborns are asymptomatic
at birth, they display higher frequencies of prematurity, low birth weight, and lower
Apgar scores compared to uninfected ones, and some suffer from severe symptoms.
If not diagnosed and treated, infected newborns are at risk of developing disabling
and life-threatening chronic pathologies later in life. The success or failure of congenital
transmission depends on interactions between the parasite, the placenta, the mother,
and the fetus. We review and discuss here the current knowledge about these
parameters, including parasite virulence factors such as exovesicles, placental tropism,
potential placental defense mechanisms, the placental transcriptome of infected
women, gene polymorphism, and the maternal and fetal/neonatal immune responses,
that might modulate the risk of T. cruzi congenital transmission.This work was supported by the ERANET-LAC grants
ELAC2014/HID-0328 and ERANet17/HLH-0142 (to UK, AO,
AS, and CT), FONDECYT 1190341 (Conicyt, Chile to UK), and
PICT 2015-0074 (FONCyT, Argentina to AS)
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