2,671 research outputs found
The peculiar nova V1309 Sco/Nova Sco 2008: A candidate twin of V838 Mon
Nova Scorpii 2008 was the target of our Directory Discretionary Time proposal
at VLT+UVES in order to study the evolution, origin and abundances of the
heavy-element absorption system recently discovered in 80% of classical novae
in outburst. The early decline of Nova Scorpii 2008 was monitored with high
resolution echelle spectroscopy at 5 different epochs. The analysis of the
absorption and the emission lines show many unusual characteristics. Nova
Scorpii 2008 is confirmed to differ from a common Classical Nova as well as a
Symbiotic Recurrent Nova, and it shows characteristics which are common to the
so called, yet debated, red-novae. The origin of this new nova remains
uncertain.Comment: 10 pages, 8 figures. Accepted by A&
Assessment of transrectal ultrasonography for detection of ovarian follicles in hair sheep
This study evaluated the accuracy of transrectal ultrasonography (US) for the determination of ovarian follicles in hair sheep. Number and size of follicles in 24 ovaries (n= 12 ewes) were determined using an ultrasound machine (Aloka SSD 500), fitted with a 7.5 MHz transrectal probe. The ovaries were collected just after US, for measurement of the number and size of follicles (postmortem findings; PM). There were no differences in the number of small (2 to 2.9 mm), medium (3 to 3.9 mm), large (℠4 mm) and total follicles/ovary as detected by US and PM (1.3 ± 0.3 vs 1.6 ± 0.3; 0.5 ± 0.2 vs 0.8 ± 0.2; 0.5 ± 0.2 vs 0.5 ± 0.2; and 2.3 ± 0.3 vs 2.9 ± 0.4; respectively). The sensitivity and predictive value of US for detection of follicles in each category were 71.1, and 87%; 68.4, and 100%; 91.7, and 100%; 73.9, and 92.7%, respectively; the correlation coefficiennts (r) for number of small, medium, large and total follicles being 0.75, 0.83, 0.96 and 0,75 (P<0.001), respectively. It was concluded that US is an efficient tool for detection and measurement of ovarian follicles in studies of the reproductive physiology in hair ewes
Infrared photometry and CaT spectroscopy of globular cluster M 28 (NGC 6626)
Recent studies show that the inner Galactic regions host genuine bulge
globular clusters, but also halo intruders, complex remnants of primordial
building blocks, and objects likely accreted during major merging events. In
this study we focus on the properties of M 28, a very old and massive cluster
currently located in the Galactic bulge. We analysed wide-field infrared
photometry collected by the VVV survey, VVV proper motions, and
intermediate-resolution spectra in the calcium triplet range for 113 targets in
the cluster area. Our results in general confirm previous estimates of the
cluster properties available in the literature. We find no evidence of
differences in metallicity between cluster stars, setting an upper limit of
Delta[Fe/H]<0.08 dex to any internal inhomogeneity. We confirm that M 28 is one
of the oldest objects in the Galactic bulge (13-14 Gyr). From this result and
the literature data, we find evidence of a weak age-metallicity relation among
bulge globular clusters that suggests formation and chemical enrichment. In
addition, wide-field density maps show that M 28 is tidally stressed and that
it is losing mass into the general bulge field. Our study indicates that M 28
is a genuine bulge globular cluster, but its very old age and its mass loss
suggest that this cluster could be the remnant of a larger structure, possibly
a primeval bulge building block.Comment: Accepted for publication in Astronomy & Astrophysic
Classification of strengthening exercises of the lower member posterior chain, based on the amplitude of muscular activation in amateur soccer players between 18-25 years
The hamstring injuries are recurrent in the sports disciplines of teams such as football, with rehabilitation being a key point to prevent future alterations. Within this process, the strengthening paradigms are rather empirical, therefore, criteria based on the exercises used are required. In this context, the objective of the present investigation is to classify the strengthening exercises of the posterior lower limb chain, based on the amplitude of muscular activation, in amateur soccer players of the AndrĂ©s Bello University (UNAB), for which a non-experimental, descriptive, cross-sectional design. The study population was 30 university students, who were studying from first to fifth year, during the academic period 2017. The participants were summoned to the Laboratory of Rehabilitation Sciences, where after signing the informed consent they had to perform a phase of heating on a cycle ergometer, then the MCIV (maximum voluntary isometric contraction) of the semimembranous, semitendinous, biceps femoral and gluteus maximus muscles was calculated, finally applying a battery of strengthening exercises, which were classified according to the intensity of muscle activation. In relation to this, it was obtained that 8 of the 13 exercises implemented were classified as low intensity (p <0.05), 3 of medium intensity (p <0.05) and 2 of high intensity (p <0.05), while the peak of amplitude of the semimembranous, semitendinous and biceps femoral muscles moved to the right in temporal terms, to the extent that the exercises classified as low, medium and high intensity are compared.Las lesiones de isquiotibiales son recurrentes en disciplinas deportivas de equipos como el fĂștbol, siendo la rehabilitaciĂłn un punto clave para prevenir alteraciones futuras. Dentro de este proceso, los paradigmas de fortalecimiento son mĂĄs bien empĂricos, por lo tanto, criterios fundamentados en torno a los ejercicios utilizados son requeridos. Bajo este contexto, el objetivo de la presente investigaciĂłn fue clasificar los ejercicios de fortalecimiento de la cadena posterior de miembro inferior, en base a la amplitud de activaciĂłn muscular, en futbolistas amateur de la Universidad AndrĂ©s Bello (UNAB), para lo cual se utilizĂł un diseño no experimental de tipo descriptivo y de corte transversal. La poblaciĂłn de estudio, fueron 30 estudiantes universitarios, que estaban cursando de primero a quinto año, durante el periodo acadĂ©mico 2017. Los participantes fueron citados al Laboratorio de Ciencias de RehabilitaciĂłn de la UNAB, en donde luego de firmar el consentimiento informado debieron realizar una fase de calentamiento en cicloergĂłmetro, posteriormente se calculĂł la MCIV (MĂĄxima contracciĂłn isomĂ©trica voluntaria) de los mĂșsculos semimembranoso, semitendinoso, bĂceps femoral y glĂșteo mayor, para finalmente aplicar una baterĂa de ejercicios de fortalecimientos, los cuales fueron clasificados segĂșn la intensidad de activaciĂłn muscular. En relaciĂłn con esto, se obtuvo que 8 de los 13 ejercicios implementados fueron clasificados de baja intensidad (p<0.05), 3 de mediana intensidad (p<0.05) y 2 de alta intensidad (p<0.05), mientras que el peak de amplitud de los mĂșsculos semimembranoso, semitendinoso y bĂceps femoral se desplazĂł a la derecha en tĂ©rminos temporales, en la medida que se comparan los ejercicios clasificados como de baja, media y alta intensidad
Discovery of catalases in members of the Chlamydiales order.
Catalase is an important virulence factor for survival in macrophages and other phagocytic cells. In Chlamydiaceae, no catalase had been described so far. With the sequencing and annotation of the full genomes of Chlamydia-related bacteria, the presence of different catalase-encoding genes has been documented. However, their distribution in the Chlamydiales order and the functionality of these catalases remain unknown. Phylogeny of chlamydial catalases was inferred using MrBayes, maximum likelihood, and maximum parsimony algorithms, allowing the description of three clade 3 and two clade 2 catalases. Only monofunctional catalases were found (no catalase-peroxidase or Mn-catalase). All presented a conserved catalytic domain and tertiary structure. Enzymatic activity of cloned chlamydial catalases was assessed by measuring hydrogen peroxide degradation. The catalases are enzymatically active with different efficiencies. The catalase of Parachlamydia acanthamoebae is the least efficient of all (its catalytic activity was 2 logs lower than that of Pseudomonas aeruginosa). Based on the phylogenetic analysis, we hypothesize that an ancestral class 2 catalase probably was present in the common ancestor of all current Chlamydiales but was retained only in Criblamydia sequanensis and Neochlamydia hartmannellae. The catalases of class 3, present in Estrella lausannensis and Parachlamydia acanthamoebae, probably were acquired by lateral gene transfer from Rhizobiales, whereas for Waddlia chondrophila they likely originated from Legionellales or Actinomycetales. The acquisition of catalases on several occasions in the Chlamydiales suggests the importance of this enzyme for the bacteria in their host environment
Benznidazole biotransformation and multiple targets in <i>Trypanosoma</i> cruzi revealed by metabolomics
<b>Background</b><p></p>
The first line treatment for Chagas disease, a neglected tropical disease caused by the protozoan parasite Trypanosoma cruzi, involves administration of benznidazole (Bzn). Bzn is a 2-nitroimidazole pro-drug which requires nitroreduction to become active, although its mode of action is not fully understood. In the present work we used a non-targeted MS-based metabolomics approach to study the metabolic response of T. cruzi to Bzn.<p></p>
<b>Methodology/Principal findings</b><p></p>
Parasites treated with Bzn were minimally altered compared to untreated trypanosomes, although the redox active thiols trypanothione, homotrypanothione and cysteine were significantly diminished in abundance post-treatment. In addition, multiple Bzn-derived metabolites were detected after treatment. These metabolites included reduction products, fragments and covalent adducts of reduced Bzn linked to each of the major low molecular weight thiols: trypanothione, glutathione, Îł-glutamylcysteine, glutathionylspermidine, cysteine and ovothiol A. Bzn products known to be generated in vitro by the unusual trypanosomal nitroreductase, TcNTRI, were found within the parasites, but low molecular weight adducts of glyoxal, a proposed toxic end-product of NTRI Bzn metabolism, were not detected.<p></p>
<b>Conclusions/significance</b><p></p>
Our data is indicative of a major role of the thiol binding capacity of Bzn reduction products in the mechanism of Bzn toxicity against T. cruzi
Highlights from the Pierre Auger Observatory
The Pierre Auger Observatory is the world's largest cosmic ray observatory.
Our current exposure reaches nearly 40,000 km str and provides us with an
unprecedented quality data set. The performance and stability of the detectors
and their enhancements are described. Data analyses have led to a number of
major breakthroughs. Among these we discuss the energy spectrum and the
searches for large-scale anisotropies. We present analyses of our X
data and show how it can be interpreted in terms of mass composition. We also
describe some new analyses that extract mass sensitive parameters from the 100%
duty cycle SD data. A coherent interpretation of all these recent results opens
new directions. The consequences regarding the cosmic ray composition and the
properties of UHECR sources are briefly discussed.Comment: 9 pages, 12 figures, talk given at the 33rd International Cosmic Ray
Conference, Rio de Janeiro 201
A search for point sources of EeV photons
Measurements of air showers made using the hybrid technique developed with
the fluorescence and surface detectors of the Pierre Auger Observatory allow a
sensitive search for point sources of EeV photons anywhere in the exposed sky.
A multivariate analysis reduces the background of hadronic cosmic rays. The
search is sensitive to a declination band from -85{\deg} to +20{\deg}, in an
energy range from 10^17.3 eV to 10^18.5 eV. No photon point source has been
detected. An upper limit on the photon flux has been derived for every
direction. The mean value of the energy flux limit that results from this,
assuming a photon spectral index of -2, is 0.06 eV cm^-2 s^-1, and no celestial
direction exceeds 0.25 eV cm^-2 s^-1. These upper limits constrain scenarios in
which EeV cosmic ray protons are emitted by non-transient sources in the
Galaxy.Comment: 28 pages, 10 figures, accepted for publication in The Astrophysical
Journa
Anisotropy and chemical composition of ultra-high energy cosmic rays using arrival directions measured by the Pierre Auger Observatory
The Pierre Auger Collaboration has reported evidence for anisotropy in the
distribution of arrival directions of the cosmic rays with energies
eV. These show a correlation with the distribution
of nearby extragalactic objects, including an apparent excess around the
direction of Centaurus A. If the particles responsible for these excesses at
are heavy nuclei with charge , the proton component of the
sources should lead to excesses in the same regions at energies . We here
report the lack of anisotropies in these directions at energies above
(for illustrative values of ). If the anisotropies
above are due to nuclei with charge , and under reasonable
assumptions about the acceleration process, these observations imply stringent
constraints on the allowed proton fraction at the lower energies
Reconstruction of inclined air showers detected with the Pierre Auger Observatory
We describe the method devised to reconstruct inclined cosmic-ray air showers
with zenith angles greater than detected with the surface array of
the Pierre Auger Observatory. The measured signals at the ground level are
fitted to muon density distributions predicted with atmospheric cascade models
to obtain the relative shower size as an overall normalization parameter. The
method is evaluated using simulated showers to test its performance. The energy
of the cosmic rays is calibrated using a sub-sample of events reconstructed
with both the fluorescence and surface array techniques. The reconstruction
method described here provides the basis of complementary analyses including an
independent measurement of the energy spectrum of ultra-high energy cosmic rays
using very inclined events collected by the Pierre Auger Observatory.Comment: 27 pages, 19 figures, accepted for publication in Journal of
Cosmology and Astroparticle Physics (JCAP
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