1,238 research outputs found
Non-Abelian Chern-Simons-Higgs vortices with a quartic potential
We have constructed numerically non-Abelian vortices in an SU(2)
Chern-Simons-Higgs theory with a quartic Higgs potential. We have analyzed
these solutions in detail by means of improved numerical codes and found some
unexpected features we did not find when a sixth-order Higgs potential was
used. The generic non-Abelian solutions have been generated by using their
corresponding Abelian counterparts as initial guess. Typically, the energy of
the non-Abelian solutions is lower than that of the corresponding Abelian one
(except in certain regions of the parameter space). Regarding the angular
momentum, the Abelian solutions possess the maximal value, although there exist
non-Abelian solutions which reach that maximal value too. In order to classify
the solutions it is useful to consider the non-Abelian solutions with
asymptotically vanishing component of the gauge potential, which may be
labelled by an integer number . For vortex number and above, we have
found uniqueness violation: two different non-Abelian solutions with all the
global charges equal. Finally, we have investigated the limit of infinity Higgs
self-coupling parameter and found a piecewise Regge-like relation between the
energy and the angular momentum.Comment: 9 pages, 13 figure
The dynamically hot stellar halo around NGC 3311: a small cluster-dominated central galaxy
An important open question is the relation between intracluster light and the
halos of central galaxies in galaxy clusters. Here we report results from an on
going project with the aim to characterize the dynamical state in the core of
the Hydra I (Abell 1060) cluster around NGC 3311. Methods: We analyze deep
long-slit absorption line spectra reaching out to ~25 kpc in the halo of NGC
3311. Results: We find a very steep increase in the velocity dispersion profile
from a central sigma_0=150 km/s to sigma_out ~450 km/s at R ~ 12 kpc. Farther
out, to ~25 kpc, sigma appears to be constant at this value, which is ~60% of
the velocity dispersion of the Hydra I galaxies. With its dynamically hot halo
kinematics, NGC 3311 is unlike other normal early-type galaxies. Conclusions:
These results and the large amount of dark matter inferred from X-rays around
NGC 3311 suggest that the stellar halo of this galaxy is dominated by the
central intracluster stars of the cluster, and that the transition from
predominantly galaxy-bound stars to cluster stars occurs in the radial range 4
to 12 kpc from the center of NGC 3311. We comment on the wide range of halo
kinematics observed in cluster central galaxies, depending on the evolutionary
state of their host clusters.Comment: 5 pages, 4 figures, 1 table, accepted for publication in A&
Expressão e distribuição da conexina 32 em fígados de ratos com fibrose induzida experimentalmente
The connexin 32 (Cx32) is a protein that forms the channels that promote the gap junction intercellular communication (GJIC) in the liver, allowing the diffusion of small molecules through cytosol from cell-to-cell. Hepatic fibrosis is characterized by a disruption of normal tissue architeture by cellular lesions, and may alter the GJIC. This work aimed to study the expression and distribution of Cx32 in liver fibrosis induced by the oral administration of dimethylnitrosamine in female Wistar rats. The necropsy of the rats was carried out after five weeks of drug administration. They presented a hepatic fibrosis state. Sections from livers with fibrosis and from control livers were submitted to immunohistochemical, Real Time-PCR and Western-Blot analysis to Cx32. In fibrotic livers the Cxs were diffusely scattered in the cytoplasm, contrasting with the control livers, where the Cx32 formed junction plaques at the cell membrane. Also it was found a decrease in the gene expression of Cx32 without reduction in the protein quantity when compared with controls. These results suggest that there the mechanism of intercellular communication between hepatocytes was reduced by the fibrotic process, which may predispose to the occurrence of a neoplastic process, taken in account that connexins are considered tumor suppressing genes.A conexina 32 (Cx32) é uma proteína que constitui os canais que promovem as comunicações intercelulares via junções comunicantes (CIJC) no fígado, permitindo difusão de pequenas moléculas citoplasmáticas de uma célula à outra. A fibrose hepática caracteriza-se pela alteração da arquitetura normal do fígado e podem alterar as CIJCs. O objetivo deste trabalho foi estudar a expressão e distribuição de Cx32 na fibrose hepática. O objetivo do presente trabalho foi estudar a expressão e distribuição da Cx32 em fígados com fibrose induzida pela administração oral de dimetilnitrosamina em fêmeas de ratos Wistar. A necropsia foi realizada após cinco semanas da última administração da droga e observou-se um quadro de fibrose hepática. Amostras dos fígados com fibrose e de animais controle foram submetidas à análise imunoistoquímica, por Real Time-PCR e por Western-Blot verificando-se a presença de Cx32 difusa e dispersa no citoplasma dos fígados com fibrose. No grupo controle a Cx32 localizou-se na membrana citoplasmática com a formação de placas juncionais. O fígado com fibrose também revelou diminuição da expressão gênica de Cx32, embora sem a redução da quantidade do produto protéico, quando comparado ao grupo controle. Estes resultados sugerem que o mecanismo de comunicação intercelular entre os hepatócitos reduziu-se durante o processo fibrótico, o que pode predispor a ocorrência de processos neoplásicos, uma vez que as conexinas são consideradas genes supressores de tumores.FAPESPCNP
Resolving galaxies in time and space: II: Uncertainties in the spectral synthesis of datacubes
In a companion paper we have presented many products derived from the
application of the spectral synthesis code STARLIGHT to datacubes from the
CALIFA survey, including 2D maps of stellar population properties and 1D
averages in the temporal and spatial dimensions. Here we evaluate the
uncertainties in these products. Uncertainties due to noise and spectral shape
calibration errors and to the synthesis method are investigated by means of a
suite of simulations based on 1638 CALIFA spectra for NGC 2916, with
perturbations amplitudes gauged in terms of the expected errors. A separate
study was conducted to assess uncertainties related to the choice of
evolutionary synthesis models. We compare results obtained with the Bruzual &
Charlot models, a preliminary update of them, and a combination of spectra
derived from the Granada and MILES models. About 100k CALIFA spectra are used
in this comparison.
Noise and shape-related errors at the level expected for CALIFA propagate to
0.10-0.15 dex uncertainties in stellar masses, mean ages and metallicities.
Uncertainties in A_V increase from 0.06 mag in the case of random noise to 0.16
mag for shape errors. Higher order products such as SFHs are more uncertain,
but still relatively stable. Due to the large number statistics of datacubes,
spatial averaging reduces uncertainties while preserving information on the
history and structure of stellar populations. Radial profiles of global
properties, as well as SFHs averaged over different regions are much more
stable than for individual spaxels. Uncertainties related to the choice of base
models are larger than those associated with data and method. Differences in
mean age, mass and metallicity are ~ 0.15 to 0.25 dex, and 0.1 mag in A_V.
Spectral residuals are ~ 1% on average, but with systematic features of up to
4%. The origin of these features is discussed. (Abridged)Comment: A&A, accepte
Avaliação da eficácia do aluminosilicato de sódio hidratado na prevenção de câncer hepático induzido por aflatoxina em truta arco-íris
The use of aluminum silicates for decontaminating animal feed containing aflatoxins has yielded encouraging results in chicken and turkey poults. In contrast, very few studies have tested these substances in aquaculture. In this work, we investigated the efficacy of a trout diet containing 0.5% hydrated sodium aluminosilicate (HSAS) in protecting against contamination with aflatoxin B1. Trout were reared on these diets for one year and the experimental groups were examined monthly for hepatic presumptive preneoplastic and neoplastic lesions. Regardless of the presence of HSAS, all of the fish that received aflatoxin in their diet have shown hepatic lesions indicative of a carcinogenic process, presenting also the development of cancer in some fish. The concentration of HSAS used in this study was ineffective in preventing the onset of hepatic lesions induced by aflatoxin B1 in rainbow trout.Resultados encorajadores têm sido observados com o emprego de aluminosilicatos para descontaminação de ração contendo aflatoxina destinada à avicultura. No entanto, raros estudos têm sido destinados a testar essa substância em aqüicultura. Assim, no presente trabalho, foi investigada a eficácia do aluminosilicato de sódio hidratado (HSAS, 0,5%) em proteger a truta arco-íris dos danos hepáticos causados por ração contaminada com aflatoxina B1. Os grupos experimentais foram alimentados com suas respectivas dietas durante 12 meses, mensalmente cada grupo foi amostrado para análises anatomopatológica e histopatológica para verificação da presença de lesões hepáticas. Apesar da presença de HSAS, todos os grupos que receberam dieta contaminada com aflatoxina B1 apresentaram lesões hepáticas indicativas do processo carcinogênico, sendo que exemplares alimentados com essas dietas por mais longo prazo apresentaram hepatocarcinoma ou colangiocarcinoma. Estes resultados indicaram que a concentração de HSAS usada no presente estudo não foi efetiva em prevenir o desenvolvimento de lesões hepáticas induzidas por aflatoxina B1 em truta arco-íris.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundo de Apoio ao Ensino, Pesquisa e Extensão da Universidade Estadual de Campina
Ionized gas kinematics of galaxies in the CALIFA survey I: Velocity fields, kinematic parameters of the dominant component, and presence of kinematically distinct gaseous systems
This work provides an overall characterization of the kinematic behavior of
the ionized gas of the galaxies included in the Calar Alto Legacy Integral
field Area (CALIFA), offering kinematic clues to potential users of this survey
for including kinematical criteria for specific studies. From the first 200
galaxies observed by CALIFA, we present the 2D kinematic view of the 177
galaxies satisfying a gas detection threshold. After removing the stellar
contribution, we used the cross-correlation technique to obtain the radial
velocity of the dominant gaseous component. The main kinematic parameters were
directly derived from the radial velocities with no assumptions on the internal
motions. Evidence of the presence of several gaseous components with different
kinematics were detected by using [OIII] profiles. Most objects in the sample
show regular velocity fields, although the ionized-gas kinematics are rarely
consistent with simple coplanar circular motions. 35% of the objects present
evidence of a displacement between the photometric and kinematic centers larger
than the original spaxel radii. Only 17% of the objects in the sample exhibit
kinematic lopsidedness when comparing receding and approaching sides of the
velocity fields, but most of them are interacting galaxies exhibiting nuclear
activity. Early-type galaxies in the sample present clear photometric-kinematic
misaligments. There is evidence of asymmetries in the emission line profiles
suggesting the presence of kinematically distinct gaseous components at
different distances from the nucleus. This work constitutes the first
determination of the ionized gas kinematics of the galaxies observed in the
CALIFA survey. The derived velocity fields, the reported kinematic
peculiarities and the identification of the presence of several gaseous
components might be used as additional criteria for selecting galaxies for
specific studies.Comment: 38 pages, 16 figures, 4 tables. Paper accepted for publication in A&
Stellar Population gradients in galaxy discs from the CALIFA survey
While studies of gas-phase metallicity gradients in disc galaxies are common,
very little has been done in the acquisition of stellar abundance gradients in
the same regions. We present here a comparative study of the stellar
metallicity and age distributions in a sample of 62 nearly face-on, spiral
galaxies with and without bars, using data from the CALIFA survey. We measure
the slopes of the gradients and study their relation with other properties of
the galaxies. We find that the mean stellar age and metallicity gradients in
the disc are shallow and negative. Furthermore, when normalized to the
effective radius of the disc, the slope of the stellar population gradients
does not correlate with the mass or with the morphological type of the
galaxies. Contrary to this, the values of both age and metallicity at 2.5
scale-lengths correlate with the central velocity dispersion in a similar
manner to the central values of the bulges, although bulges show, on average,
older ages and higher metallicities than the discs. One of the goals of the
present paper is to test the theoretical prediction that non-linear coupling
between the bar and the spiral arms is an efficient mechanism for producing
radial migrations across significant distances within discs. The process of
radial migration should flatten the stellar metallicity gradient with time and,
therefore, we would expect flatter stellar metallicity gradients in barred
galaxies. However, we do not find any difference in the metallicity or age
gradients in galaxies with without bars. We discuss possible scenarios that can
lead to this absence of difference.Comment: 24 pages, 17 figures, accepted for publication in A&
REST PERIOD FOR STRENGTH RECOVERY DURING ISOKINETIC TESTING
The purpose of this study was to replicate the testing protocol used by Parcell, Sawyer, Valmor, Tricoli and Chinevere (2002) with a female population to determine whether females had the same recovery responses as males when performing isokinetic tests. Eleven female subjects were recruited and tested on 4 separate occasions. A 4 X 5 repeated measures ANOVA was used to analyze the data (p < .05). There were no significant findings. The conclusions were that the females in the study did not understand maximal force production, peak torque averages don't provide the same information as the highest peak torque per set, or the females need more time to become attenuated to the testing apparatus
CALIFA, the Calar Alto Legacy Integral Field Area survey: I. Survey presentation
We present here the Calar Alto Legacy Integral Field Area (CALIFA) survey,
which has been designed to provide a first step in this direction.We summarize
the survey goals and design, including sample selection and observational
strategy.We also showcase the data taken during the first observing runs
(June/July 2010) and outline the reduction pipeline, quality control schemes
and general characteristics of the reduced data. This survey is obtaining
spatially resolved spectroscopic information of a diameter selected sample of
galaxies in the Local Universe (0.005< z <0.03). CALIFA has been
designed to allow the building of two-dimensional maps of the following
quantities: (a) stellar populations: ages and metallicities; (b) ionized gas:
distribution, excitation mechanism and chemical abundances; and (c) kinematic
properties: both from stellar and ionized gas components. CALIFA uses the PPAK
Integral Field Unit (IFU), with a hexagonal field-of-view of
\sim1.3\sq\arcmin', with a 100% covering factor by adopting a three-pointing
dithering scheme. The optical wavelength range is covered from 3700 to 7000
{\AA}, using two overlapping setups (V500 and V1200), with different
resolutions: R\sim850 and R\sim1650, respectively. CALIFA is a legacy survey,
intended for the community. The reduced data will be released, once the quality
has been guaranteed. The analyzed data fulfill the expectations of the original
observing proposal, on the basis of a set of quality checks and exploratory
analysis.
We conclude from this first look at the data that CALIFA will be an important
resource for archaeological studies of galaxies in the Local Universe.Comment: 32 pages, 29 figures, Accepted for publishing in Astronomy and
Astrophysic
Two-dimensional multi-component photometric decomposition of CALIFA galaxies
We present a two-dimensional multi-component photometric decomposition of 404 galaxies from the Calar Alto Legacy Integral Field Area Data Release 3 (CALIFA-DR3). They represent all possible galaxies with no clear signs of interaction and not strongly inclined in the final CALIFA data release. Galaxies are modelled in the g, r, and i Sloan Digital Sky Survey (SDSS) images including, when appropriate, a nuclear point source, bulge, bar, and an exponential or broken disc component. We use a human-supervised approach to determine the optimal number of structures to be included in the fit. The dataset, including the photometric parameters of the CALIFA sample, is released together with statistical errors and a visual analysis of the quality of each fit. The analysis of the photometric components reveals a clear segregation of the structural composition of galaxies with stellar mass. At high masses (log(M⋆/M⊙) > 11), the galaxy population is dominated by galaxies modelled with a single Sérsic or a bulge+disc with a bulge-to-total (B/T) luminosity ratio B/T > 0.2. At intermediate masses (9.5 < log(M⋆/M⊙) < 11), galaxies described with bulge+disc but B/T < 0.2 are preponderant, whereas, at the low mass end (log(M⋆/M⊙)< 9.5), the prevailing population is constituted by galaxies modelled with either pure discs or nuclear point sources+discs (i.e., no discernible bulge). We obtain that 57% of the volume corrected sample of disc galaxies in the CALIFA sample host a bar. This bar fraction shows a significant drop with increasing galaxy mass in the range 9.5 < log(M⋆/M⊙) < 11.5. The analyses of the extended multi-component radial profile result in a volume-corrected distribution of 62%, 28%, and 10% for the so-called Type I (pure exponential), Type II (down-bending), and Type III (up-bending) disc profiles, respectively. These fractions are in discordance with previous findings. We argue that the different methodologies used to detect the breaks are the main cause for these differences.PostprintPeer reviewe
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