211 research outputs found
Impact of gaps in the asteroseismic characterization of pulsating stars. I. On the efficiency of pre-whitening
It is known that the observed distribution of frequencies in CoRoT and Kepler
{\delta} Scuti stars has no parallelism with any theoretical model.
Pre-whitening is a widespread technique in the analysis of time series with
gaps from pulsating stars located in the classical instability strip such as
{\delta} Scuti stars. However, some studies have pointed out that this
technique might introduce biases in the results of the frequency analysis. This
work aims at studying the biases that can result from pre-whitening in
asteroseismology. The results will depend on the intrinsic range and
distribution of frequencies of the stars. The periodic nature of the gaps in
CoRoT observations, just in the range of the pulsational frequency content of
the {\delta} Scuti stars, is shown to be crucial to determine their oscillation
frequencies, the first step to perform asteroseismolgy of these objects. Hence,
here we focus on the impact of pre-whitening on the asteroseismic
characterization of {\delta} Scuti stars. We select a sample of 15 {\delta}
Scuti stars observed by the CoRoT satellite, for which ultra-high quality
photometric data have been obtained by its seismic channel. In order to study
the impact on the asteroseismic characterization of {\delta} Scuti stars we
perform the pre-whitening procedure on three datasets: gapped data, linearly
interpolated data, and ARMA interpolated data. The different results obtained
show that at least in some cases pre-whitening is not an efficient procedure
for the deconvolution of the spectral window. therefore, in order to reduce the
effect of the spectral window to the minimum it is necessary to interpolate
with an algorithm that is aimed to preserve the original frequency content, and
not only to perform a pre-whitening of the data.Comment: 27 pages, 47 figures Tables and typos fixe
Primary pulmonary melanoma: the unexpected tumour
A 62-year-old woman was referred to our pulmonology team with exertional dyspnoea and chest tightness of 2 months duration. Her medical history included cervical cancer and thyroid nodules. Imaging studies showed collapse of left upper lobe. Fiberoptic bronchoscopy unveiled an endoluminal lesion and bronchial biopsy displayed features of melanoma. She denied a history of melanoma or excision of lesions of skin, mucous membranes or the eye. A thorough evaluation including combined positron emission tomography with CT scan excluded other possible sites of primary melanoma, but there was a metastasis in a thoracic vertebra. Palliative radiotherapy of the spine was performed. Chemotherapy initiation with dacarbazine was postponed by the appearance of a malignant pleural effusion, confirmed by pleural fluid cytology. After four cycles chemotherapy was discontinued due to disease progression. The patient is still alive with a follow-up of 12 months, currently on best supportive care
Clinical applications of pharmacogenomics
Indexación: Scopus.Pharmacogenomics is an emergent field aimed at tailoring pharmacological therapy. Genetic polymorphisms can modify the expression and function of enzymes and proteins involved in drug metabolism, affecting absorption, distribution, biotransformation and excretion as well as the drug-target interaction. Therefore, the presence of allelic variants will classify people as poor, extensive or rapid/ultra rapid metabolizers, modifying drug efficacy and safety. In this work, the state of art in relation to this discipline is presented and the genetic variants of enzymes that are involved in drug pharmacokinetics or pharmacodynamics are described. The effects of these variants on the therapeutic response to drugs used in our country are also discussed.http://ref.scielo.org/4y6n8
La convivencia del ser humano según Xavier Zubiri
La presente investigación tiene por objeto examinar la manera como Xavier Zubiri aborda desde la metafísica el dinamismo de la convivencia, en su obra Estructura Dinámica de la Realidad. Nuestra revisión se inicia con una aproximación a su concepción filosófica en general, para luego enfocarnos en su pensamiento metafísico y allí analizar los aspectos tratados propiamente sobre el dinamismo de la convivencia
GW150914: First search for the electromagnetic counterpart of a gravitational-wave event by the TOROS collaboration
We present the results of the optical follow-up conducted by the TOROS
collaboration of the first gravitational-wave event GW150914. We conducted
unfiltered CCD observations (0.35-1 micron) with the 1.5-m telescope at Bosque
Alegre starting ~2.5 days after the alarm. Given our limited field of view
(~100 square arcmin), we targeted 14 nearby galaxies that were observable from
the site and were located within the area of higher localization probability.
We analyzed the observations using two independent implementations of
difference-imaging algorithms, followed by a Random-Forest-based algorithm to
discriminate between real and bogus transients. We did not find any bona fide
transient event in the surveyed area down to a 5-sigma limiting magnitude of
r=21.7 mag (AB). Our result is consistent with the LIGO detection of a binary
black hole merger, for which no electromagnetic counterparts are expected, and
with the expected rates of other astrophysical transients.Comment: ApJ Letters, in pres
Cosmological Constraints from a Combination of Galaxy Clustering and Lensing -- III. Application to SDSS Data
We simultaneously constrain cosmology and galaxy bias using measurements of
galaxy abundances, galaxy clustering and galaxy-galaxy lensing taken from the
Sloan Digital Sky Survey. We use the conditional luminosity function (which
describes the halo occupation statistics as function of galaxy luminosity)
combined with the halo model (which describes the non-linear matter field in
terms of its halo building blocks) to describe the galaxy-dark matter
connection. We explicitly account for residual redshift space distortions in
the projected galaxy-galaxy correlation functions, and marginalize over
uncertainties in the scale dependence of the halo bias and the detailed
structure of dark matter haloes. Under the assumption of a spatially flat,
vanilla {\Lambda}CDM cosmology, we focus on constraining the matter density,
{\Omega}m, and the normalization of the matter power spectrum, {\sigma}8, and
we adopt WMAP7 priors for the spectral index, the Hubble parameter, and the
baryon density. We obtain that \Omegam = 0.278_{-0.026}^{+0.023} and {\sigma}8
= 0.763_{-0.049}^{+0.064} (95% CL). These results are robust to uncertainties
in the radial number density distribution of satellite galaxies, while allowing
for non-Poisson satellite occupation distributions results in a slightly lower
value for {\sigma}8 (0.744_{-0.047}^{+0.056}). These constraints are in
excellent agreement (at the 1{\sigma} level) with the cosmic microwave
background constraints from WMAP. This demonstrates that the use of a realistic
and accurate model for galaxy bias, down to the smallest non-linear scales
currently observed in galaxy surveys, leads to results perfectly consistent
with the vanilla {\Lambda}CDM cosmology.Comment: 21 pages, 9 figures, 5 tables, submitted to MNRA
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