368 research outputs found
Water demand prospects for the irrigation in São Francisco River.
Abstract: This study analyzed how the irrigation expansion in São Francisco Hydrographic Region (SFRH) would affect the water availability in four specifics physiographic regions into SFRH (Upper, Middle, sub-Middle, and Lower). The TERM-BR model was used to simulate expansion scenarios in irrigated areas aiming to verify the impact in the water use for 2025 and 2035 according to with National Water Resources Plan (PNRH), and Water Resources Plan for the São Francisco River (SFP). The simulations were carried out for areas deemed potentially suitable for irrigation based on the Ministry of National Integration report (MI). The Climatic Water Balance (CWB) was estimated for São Francisco hydrographic region (SFRH) in order to compare regional water supply and demand. Results suggest that cities located in Upper and Middle São Francisco region would present greater irrigation potential due to the water availability and the proximity to neighborhoods that also irrigate. The comparative result of the CWB and the TERM-BR model shown water availability problems in the states of Alagoas and Pernambuco in particular and cities located in São Francisco Lower.GTAP Resource #5725
Dissecting X-ray-emitting Gas around the Center of our Galaxy
Most supermassive black holes (SMBHs) are accreting at very low levels and
are difficult to distinguish from the galaxy centers where they reside. Our own
Galaxy's SMBH provides a uniquely instructive exception, and we present a
close-up view of its quiescent X-ray emission based on 3 mega-second of Chandra
observations. Although the X-ray emission is elongated and aligns well with a
surrounding disk of massive stars, we can rule out a concentration of low-mass
coronally active stars as the origin of the emission based on the lack of
predicted Fe Kalpha emission. The extremely weak H-like Fe Kalpha line further
suggests the presence of an outflow from the accretion flow onto the SMBH.
These results provide important constraints for models of the prevalent
radiatively inefficient accretion state.Comment: 18 pages, 5 PDF figures, pdflatex format; Final version, published in
Scienc
Thermal torque effects on the migration of growing low-mass planets
As planets grow the exchange of angular momentum with the gaseous component ofthe protoplanetary disc produces a net torque resulting in a variation of the semi-major axis of the planet. For low-mass planets not able to open a gap in the gaseousdisc this regime is known as type I migration. Pioneer works studied this mechanismin isothermal discs finding fast inward type I migration rates that were unable toreproduce the observed properties of extrasolar planets. In the last years, several im-provements have been made in order to extend the study of type I migration rates tonon-isothermal discs. Moreover, it was recently shown that if the planet?s luminositydue to solid accretion is taken into account, inward migration could be slowed downand even reversed. In this work, we study the planet formation process incorporating,and comparing, updated type I migration rates for non-isothermal discs and the role ofplanet?s luminosity over such rates. We find that the latter can have important effectson planetary evolution, producing a significant outward migration for the growingplanets.Fil: Guilera, Octavio Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Cuello, N.. Pontificia Universidad Católica de Chile; ChileFil: Montesinos, M.. Universidad de Valparaíso; ChileFil: Miller Bertolami, Marcelo Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Ronco, María Paula. Pontificia Universidad Católica de Chile; Chile. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Cuadra, J.. Pontificia Universidad Católica de Chile; ChileFil: Masset, F. S.. Universidad Autonoma de Mexico; Méxic
Low angular momentum flow model of Sgr A* activity
Sgr A* is the closest massive black hole and can be observed with the highest
angular resolution. Nevertheless, our current understanding of the accretion
process in this source is very poor. The inflow is almost certainly of low
radiative efficiency and it is accompanied by a strong outflow and the flow is
strongly variable but the details of the dynamics are unknown. Even the amount
of angular momentum in the flow is an open question. Here we argue that low
angular momentum scenario is better suited to explain the flow variability. We
present a new hybrid model which describes such a flow and consists of an outer
spherically symmetric Bondi flow and an inner axially symmetric flow described
through MHD simulations. The assumed angular momentum of the matter is low,
i.e. the corresponding circularization radius in the equatorial plane of the
flow is just above the innermost stable circular orbit in pseudo-Newtonian
potential. We compare the radiation spectrum from such a flow to the broad band
observational data for Sgr A*.Comment: Proceedings of the AHAR 2008 Conference: The Universe under the
Microscope; Astrophysics at High Angular Resolution, Bad Honef
Séries temporais de índices de vegetação para identificação de quebra de safra.
A agricultura está sujeita a intempéries que afetam a produção negativamente. Monitorar quebras causadas por clima adverso, em termos de quantidade perdida e área afetada, é de interesse para produtores, mercado consumidor e empresas do agronegócio. O sensoriamento remoto tem se mostrado útil para o monitoramento agrícola, principalmente com o uso de séries temporais. Esse trabalho utilizou séries de EVI/MODIS para calcular o Índice de Vegetação Padronizado (IVP), os quais foram comparados com a produtividade de soja nos municípios da região Sul do País. Os dados de sensoriamento remoto foram processados na plataforma de computação em nuvem Google Earth Engine, que se mostrou apropriada para manejar grandes volumes de dados. O IVP médio dos municípios mostrou boa relação com a produtividade de soja. Dessa forma, esse índice poderá ser utilizado para identificação de áreas afetadas por quebra de safra e para o monitoramento da produção agrícola.SBIAgro 2017. Na publicação: Santiago Viana Cuadra
Séries temporais de índices de vegetação para identificação de quebra de safra.
A agricultura está sujeita a intempéries que afetam a produção negativamente. Monitorar quebras causadas por clima adverso, em termos de quantidade perdida e área afetada, é de interesse para produtores, mercado consumidor e empresas do agronegócio. O sensoriamento remoto tem se mostrado útil para o monitoramento agrícola, principalmente com o uso de séries temporais. Esse trabalho utilizou séries de EVI/MODIS para calcular o Índice de Vegetação Padronizado (IVP), os quais foram comparados com a produtividade de soja nos municípios da região Sul do País. Os dados de sensoriamento remoto foram processados na plataforma de computação em nuvem Google Earth Engine, que se mostrou apropriada para manejar grandes volumes de dados. O IVP médio dos municípios mostrou boa relação com a produtividade de soja. Dessa forma, esse índice poderá ser utilizado para identificação de áreas afetadas por quebra de safra e para o monitoramento da produção agrícola.SBIAgro 2017. Na publicação: Santiago Viana Cuadra
Spherically Symmetric Accretion Flows: Minimal Model with MHD Turbulence
The first spherical accretion model was developed 55 years ago, but the
theory is yet far from being complete. The real accretion flow was found to be
time-dependent and turbulent. This paper presents the minimal MHD spherical
accretion model that separately deals with turbulence. Treatment of turbulence
is based on simulations of several regimes of collisional MHD. The effects of
freezing-in amplification, dissipation, dynamo action, isotropization, and
constant magnetic helicity are self-consistently included. The assumptions of
equipartition and magnetic field isotropy are released. Correct dynamics of
magnetized flow is calculated. Diffusion, convection, and radiation are not
accounted for. Two different types of Radiatively Inefficient accretion flows
are found: a transonic non-rotating flow (I), a flow with effective transport
of angular momentum outward (II). Non-rotating flow has an accretion rate
several times smaller than Bondi rate, because turbulence inhibits accretion.
Flow with angular momentum transport has accretion rate about 10-100 times
smaller than Bondi rate. The effects of highly helical turbulence, states of
outer magnetization, and different equations of state are discussed. The flows
were found to be convectively stable on average, despite gas entropy increases
inward. The proposed model has a small number of free parameters and the
following attractive property. Inner density in the non-rotating magnetized
flow was found to be several times lower than density in a non-magnetized
accretion. Still several times lower density is required to explain the
observed low IR luminosity and low Faraday rotation measure of accretion onto
Sgr A*.Comment: Accepted for publication in ApJS. 52 pages, 7 figure
In vitro-generated Tc17 cells present a memory phenotype and serve as a reservoir of Tc1 cells in vivo
Indexación: Scopus.Memory CD8+ T cells are ideal candidates for cancer immunotherapy because they can mediate long-term protection against tumors. However, the therapeutic potential of different in vitro-generated CD8+ T cell effector subsets to persist and become memory cells has not been fully characterized. Type 1 CD8+ T (Tc1) cells produce interferon-γ and are endowed with high cytotoxic capacity, whereas IL-17-producing CD8+ T (Tc17) cells are less cytotoxic but display enhanced self-renewal capacity. We sought to evaluate the functional properties of in vitro-generated Tc17 cells and elucidate their potential to become long lasting memory cells. Our results show that in vitro-generated Tc17 cells display a greater in vivo persistence and expansion in response to secondary antigen stimulation compared to Tc1 cells. When transferred into recipient mice, Tc17 cells persist in secondary lymphoid organs, present a recirculation behavior consistent with central memory T cells, and can shift to a Tc1 phenotype. Accordingly, Tc17 cells are endowed with a higher mitochondrial spare respiratory capacity than Tc1 cells and express higher levels of memory-related molecules than Tc1 cells. Together, these results demonstrate that in vitro-generated Tc17 cells acquire a central memory program and provide a lasting reservoir of Tc1 cells in vivo, thus supporting the use of Tc17 lymphocytes in the design of novel and more effective therapies.https://www.frontiersin.org/articles/10.3389/fimmu.2018.00209/ful
Coordinated mm/sub-mm observations of Sagittarius A* in May 2007
At the center of the Milky Way, with a distance of ~8 kpc, the compact source
Sagittarius A* (SgrA*) can be associated with a super massive black hole of
~4x10^6 solar masses. SgrA* shows strong variability from the radio to the
X-ray wavelength domains. Here we report on simultaneous
NIR/sub-millimeter/X-ray observations from May 2007 that involved the NACO
adaptive optics (AO) instrument at the European Southern Observatory's Very
Large Telescope, the Australian Telescope Compact Array (ATCA), the US mm-array
CARMA, the IRAM 30m mm-telescope, and other telescopes. We concentrate on the
time series of mm/sub-mm data from CARMA, ATCA, and the MAMBO bolometer at the
IRAM 30m telescope.Comment: 7 pages, 3 figures, contribution for the conference "The Universe
under the Microscope" (AHAR 2008), to be published in Journal of Physics:
Conference Series by Institute of Physics Publishin
Coordinated multi-wavelength observations of Sgr A*
We report on recent near-infrared (NIR) and X-ray observations of Sagittarius
A* (Sgr A*), the electromagnetic manifestation of the ~4x10^6 solar masses
super-massive black hole (SMBH) at the Galactic Center. The goal of these
coordinated multi-wavelength observations is to investigate the variable
emission from Sgr A* in order to obtain a better understanding of the
underlying physical processes in the accretion flow/outflow. The observations
have been carried out using the NACO adaptive optics (AO) instrument at the
European Southern Observatory's Very Large Telescope (July 2005, May 2007) and
the ACIS-I instrument aboard the Chandra X-ray Observatory (July 2005). We
report on a polarized NIR flare synchronous to a 8x1033 erg/s X-ray flare in
July 2005, and a further flare in May 2007 that shows the highest sub-flare to
flare contrast observed until now. The observations can be interpreted in the
framework of a model involving a temporary disk with a short jet. In the disk
component flux density variations can be explained due to hot spots on
relativistic orbits around the central SMBH. The variations of the
sub-structures of the May 2007 flare are interpreted as a variation of the hot
spot structure due to differential rotation within the disk.Comment: 15 pages, 7 figures, contribution for the conference "The Universe
under the Microscope" (AHAR 2008), to be published in Journal of Physics:
Conference Series by Institute of Physics Publishin
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