1,579 research outputs found
Depression in autoimmune diseases
Up to 50% of patients with autoimmune diseases show an impairment of health-related quality of life and exhibit depression-like symptoms. The immune system not only leads to inflammation in affected organs, but also mediates behavior abnormalities including fatigue and depression-like symptoms. This review focuses on the different pathways involved in the communication of the immune system with the neuronal network and the body's timing system. The latter is built up by a hierarchically organized expression of clock genes. As discussed here, the activation of the immune system interferes with high amplitude expression of clock genes, an effect which may play a pivotal role in depression-like behavior in autoimmune diseases
KAIUM at DAΦNE
The possibility of producing and detecting at DAΦNE a new hydrogen isotope formed by a (K + e − ) bound system (Kaium) is addressed, considering a dedicated, and relatively simple experiment of short duration. If Kaium will be detected, it could in perspective pave the way for a series of highly sophisticated experiments focused on the precision measurement of several observables, as the K + − K − mass difference, strictly related to CPT invariance
Keck/MOSFIRE Spectroscopy of z=7-8 Galaxies: Ly Emission from a Galaxy at z=7.66
We report the results from some of the deepest Keck/Multi-Object Spectrometer
For Infra-Red Exploration data yet obtained for candidate
galaxies. Our data show one significant line detection with 6.5
significance in our combined 10 hr of integration which is independently
detected on more than one night, thus ruling out the possibility that the
detection is spurious. The asymmetric line profile and non-detection in the
optical bands strongly imply that the detected line is Ly emission from
a galaxy at (Ly, making it the fourth
spectroscopically confirmed galaxy via Ly at . This galaxy is
bright in the rest-frame ultraviolet (UV; ) with a
moderately blue UV slope (), and exhibits a
rest-frame Ly equivalent width of EW(Ly) \AA. The non-detection of the 11 other 7-8
galaxies in our long 10 hr integration, reaching a median 5 sensitivity
of 28 \AA\ in the rest-frame EW(Ly), implies a 1.3 deviation
from the null hypothesis of a non-evolving distribution in the rest-frame
EW(Ly) between and 7-8. Our results are consistent with
previous studies finding a decline in Ly emission at , which may
signal the evolving neutral fraction in the intergalactic medium at the end of
the reionization epoch, although our weak evidence suggests the need for a
larger statistical sample to allow for a more robust conclusion.Comment: 10 pages, 4 figures, ApJ, in pres
Natural convection in a partially open square cavity with internal heat source: An analysis of the opening mass flow
AbstractA steady buoyancy-driven flow of air in a partially open square 2D cavity with internal heat source, adiabatic bottom and top walls, and vertical walls maintained at different constant temperatures is investigated numerically in this work. A heat source with 1% of the cavity volume is present in the center of the bottom wall. The cold right wall contains a partial opening occupying 25%, 50% or 75% of the wall. The influence of the temperature gradient between the verticals walls was analyzed for Rae=103–105, while the influence of the heat source was evaluated through the relation R=Rai/Rae, investigated at between 400 and 2000. Interesting results were obtained. For a low Rayleigh number, it is found that the isotherm plots are smooth and follow a parabolic shape indicating the dominance of the heat source. But as the Rae increases, the flow slowly becomes dominated by the temperature difference between the walls. It is also observed that multiple strong secondary circulations are formed for fluids with a small Rae whereas these features are absent at higher Rae. The comprehensive analysis is concluded with horizontal air velocity and temperature plots for the opening. The numerical results show a significant influence of the opening on the heat transfer in the cavity
Photometric redshifts and selection of high redshift galaxies in the NTT and Hubble Deep Fields
We present and compare in this paper new photometric redshift catalogs of the
galaxies in three public fields: the NTT Deep Field, the HDF-N and the HDF-S.
Photometric redshifts have been obtained for thewhole sample, by adopting a
minimization technique on a spectral library drawn from the Bruzual
and Charlot synthesis models, with the addition of dust and intergalactic
absorption. The accuracy, determined from 125 galaxies with known spectroscopic
redshifts, is in the redshift intervals . The global redshift distribution of I-selected galaxies shows a
distinct peak at intermediate redshifts, z~0.6 at I_{AB}<26 and z~0.8 at
I_{AB}<27.5 followed by a tail extending to z~6. We also present for the first
time the redshift distribution of the total IR-selected sample to faint limits
( and ). It is found that the number density of galaxies
at 1.25<z<1.5 is ~ 0.1 /arcmin^22 at J<=21 and ~1./arcmin^2} at J<22, and drops
to 0.3/arcmin^2 (at J<22) at 1.5<z<2. The HDFs data sets are used to compare
the different results from color selection criteria and photometric redshifts
in detecting galaxies in the redshift range 3.5<z<4.5 Photometric redshifts
predict a number of high z candidates in both the HDF-N and HDF-S that is
nearly 2 times larger than color selection criteria, and it is shown that this
is primarily due to the inclusion of dusty models that were discarded in the
original color selection criteria by Madau et al 1998. In several cases, the
selection of these objects is made possible by the constraints from the IR
bands. Finally, it is shown that galactic M stars may mimic z>5 candidates in
the HDF filter set and that the 4 brightest candidates at in the HDF-S
are indeed most likely M stars. (ABRIDGED)Comment: Version accepted on July, 20, 2000. To appear on Astronomical
Journal, Nov 2000. The data and photometric redshift catalogs presented here
are available on line at http://www.mporzio.astro.it/HIGH
Estudo e implementação de aprendizagem por reforço em redes neurais para controle de robôs móveis
Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-graduação em Ciência da ComputaçãoRobôs Móveis Inteligentes são sistemas computacionais que operam em ambientes dinâmicos e imprevisíveis. Eles interpretam dados obtidos pelos sensores que refletem eventos ocorridos e executam comandos em motores que produzem efeitos no ambiente. O grau de autonomia de um agente está relacionado à capacidade de decidir por si só como relacionar os dados dos sensores com os comandos aos atuadores em seus esforços para atingir os objetivos para os quais foi projetado. Deste modo, a capacidade de aprendizado e adaptação do agente está intimamente relacionada com o seu grau de autonomia. Dentro do paradigma de inspiração biológica adotada na arquitetura de controle PiramidNet, Redes Neurais Artificiais são as ferramentas utilizadas para implementar a inteligência e o controle dos sistemas robóticos. Entretanto, mecanismos capazes de fazer o aprendizado permanente e em tempo de operação em sistemas robóticos controlados por Redes Neurais são escassos ou ainda estão em fase inicial de desenvolvimento. Neste trabalho, pretendeu-se estudar, propor e implementar métodos que possibilitassem o aprendizado em tempo real de Robôs Móveis Inteligentes controlados por Redes Neurais Artificiais. Para tal, propôs-se uma arquitetura neural de controle capaz de apresentar características de plasticidade e de estabilidade adequadas, utilizando redes ART # Adaptive Ressonance Theory e redes MLP # Multi-Layer Perceptron, associados a um esquema de aprendizagem por reforço como metodologia de aprendizado em tempo real
Measuring the Redshift Evolution of Clustering: the Hubble Deep Field South
We present an analysis of the evolution of galaxy clustering in the redshift
interval 0<z<4.5 in the HDF-S. The HST optical data are combined with infrared
ISAAC/VLT observations, and photometric redshifts are used for all the galaxies
brighter than I_AB<27.5. The clustering signal is obtained in different
redshift bins using two different approaches: a standard one, which uses the
best redshift estimate of each object, and a second one, which takes into
account the redshift probability function of each object. This second method
makes it possible to improve the information in the redshift intervals where
contamination from objects with insecure redshifts is important. With both
methods, we find that the clustering strength up to z~3.5 in the HDF-S is
consistent with the previous results in the HDF-N. While at redshift lower than
z~1 the HDF galaxy population is un/anti-biased (b<1) with respect to the
underlying dark matter, at high redshift the bias increases up to b~2-3,
depending on the cosmological model. These results support previous claims
that, at high redshift, galaxies are preferentially located in massive haloes,
as predicted by the biased galaxy formation scenario. The impact of cosmic
errors on our analyses has been quantified, showing that errors in the
clustering measurements in the HDF surveys are indeed dominated by shot-noise
in most regimes. Future observations with instruments like the ACS on HST will
improve the S/N by at least a factor of two and more detailed analyses of the
errors will be required. In fact, pure shot-noise will give a smaller
contribution with respect to other sources of errors, such as finite volume
effects or non-Poissonian discreteness effects.Comment: 17 pages Latex, with 12 PostScript figures, Accepted for publication
in MNRA
The Optical Identification of a Primeval Galaxy at z >~ 4.4
We have obtained with the SUSI CCD camera on the ESO 3.5m NTT deep images in
the BVRI bands of the field centered on the QSO BRI 1202-0725 (). In the final combined frames the stellar images have FWHM of
1,1,0.6 and 0.65 arcsec respectively. The R and I images show clearly a galaxy
from the QSO, corresponding to kpc at .
Possible identification with the metal absorption systems seen in the line of
sight to the QSO, including the highest redshift damped system known to date at
, are discussed. We conclude that its colours can be reconciled only
with the spectrum of a primeval galaxy at z >~ 4.4, making it the most distant
galaxy detected so far. From its magnitudes and models of young galaxy
evolution we deduce that it is forming stars at a rate
yr and has an estimated age of the order of yr or less, implying
that the bulk of the stellar population formed at .Comment: 5 pages, 1 b/w + 1 color Postcript figure (6.5 Mb after
decompression). Uses mn.sty (included). To appear in MNRAS Letter
Beacons into the Cosmic Dark Ages: Boosted transmission of Ly from UV bright galaxies at
Recent detections of Lyman alpha (Ly) emission from galaxies
were somewhat unexpected given a dearth of previous non-detections in this era
when the intergalactic medium (IGM) is still highly neutral. But these
detections were from UV bright galaxies, which preferentially live in
overdensities which reionize early, and have significantly Doppler-shifted
Ly line profiles emerging from their interstellar media (ISM), making
them less affected by the global IGM state. Using a combination of reionization
simulations and empirical ISM models we show, as a result of these two effects,
UV bright galaxies in overdensities have higher transmission through
the IGM than typical field galaxies, and this boosted transmission is
enhanced as the neutral fraction increases. The boosted transmission is not
sufficient to explain the observed high Ly fraction of galaxies (Stark et al. 2017), suggesting Ly emitted by
these galaxies must be stronger than expected due to enhanced production and/or
selection effects. Despite the bias of UV bright galaxies to reside in
overdensities we show Ly observations of such galaxies can accurately
measure the global neutral hydrogen fraction, particularly when Ly from
UV faint galaxies is extinguished, making them ideal candidates for
spectroscopic follow-up into the cosmic Dark Ages.Comment: 6 pages, 5 figures. Accepted for publication in ApJ
- …