3,289 research outputs found
Application of the RMF mass model to the r-process and the influence of mass uncertainties
A new mass table calculated by the relativistic mean field approach with the
state-dependent BCS method for the pairing correlation is applied for the first
time to study r-process nucleosynthesis. The solar r-process abundance is well
reproduced within a waiting-point approximation approach. Using an exponential
fitting procedure to find the required astrophysical conditions, the influence
of mass uncertainty is investigated. R-process calculations using the FRDM,
ETFSI-Q and HFB-13 mass tables have been used for that purpose. It is found
that the nuclear physical uncertainty can significantly influence the deduced
astrophysical conditions for the r-process site. In addition, the influence of
the shell closure and shape transition have been examined in detail in the
r-process simulations.Comment: to be published in Phys. Rev. C, 22 pages, 9 figure
Nucleosynthesis in the Early Galaxy
Recent observations of r-process-enriched metal-poor star abundances reveal a
non-uniform abundance pattern for elements . Based on non-correlation
trends between elemental abundances as a function of Eu-richness in a large
sample of metal-poor stars, it is shown that the mixing of a consistent and
robust light element primary process (LEPP) and the r-process pattern found in
r-II metal-poor stars explains such apparent non-uniformity. Furthermore, we
derive the abundance pattern of the LEPP from observation and show that it is
consistent with a missing component in the solar abundances when using a recent
s-process model. As the astrophysical site of the LEPP is not known, we explore
the possibility of a neutron capture process within a site-independent
approach. It is suggested that scenarios with neutron densities
or in the range best
explain the observations.Comment: 28 pages, 7 Postscript figures. To be published in The Astrophysical
Journa
The central structure of Broad Absorption Line QSOs: observational characteristics in the cm-mm wavelength domain
Accounting for ~20% of the total QSO population, Broad Absorption Line QSOs
are still an unsolved problem in the AGN context. They present wide troughs in
the UV spectrum, due to material with velocities up to 0.2 c toward the
observer. The two models proposed in literature try to explain them as a
particular phase of the evolution of QSOs or as normal QSOs, but seen from a
particular line of sight.
We built a statistically complete sample of Radio-Loud BAL QSOs, and carried
out an observing campaign to piece together the whole spectrum in the cm
wavelength domain, and highlight all the possible differences with respect to a
comparison sample of Radio-Loud non-BAL QSOs. VLBI observations at high angular
resolution have been performed, to study the pc-scale morphology of these
objects. Finally, we tried to detect a possible dust component with
observations at mm-wavelengths.
Results do not seem to indicate a young age for all BAL QSOs. Instead a
variety of orientations and morphologies have been found, constraining the
outflows foreseen by the orientation model to have different possible angles
with respect to the jet axis
Is there an integrative center in the vertebrate brain-stem? A robotic evaluation of a model of the reticular formation viewed as an action selection device
Neurobehavioral data from intact, decerebrate, and neonatal rats, suggests that the reticular formation provides
a brainstem substrate for action selection in the vertebrate central nervous system. In this article, Kilmer,
McCulloch and Blum’s (1969, 1997) landmark reticular formation model is described and re-evaluated, both in
simulation and, for the first time, as a mobile robot controller. Particular model configurations are found to
provide effective action selection mechanisms in a robot survival task using either simulated or physical robots.
The model’s competence is dependent on the organization of afferents from model sensory systems, and a genetic
algorithm search identified a class of afferent configurations which have long survival times. The results support
our proposal that the reticular formation evolved to provide effective arbitration between innate behaviors
and, with the forebrain basal ganglia, may constitute the integrative, ’centrencephalic’ core of vertebrate brain
architecture. Additionally, the results demonstrate that the Kilmer et al. model provides an alternative form of
robot controller to those usually considered in the adaptive behavior literature
Integrando modelos de regressão fatorial e Sistema de Informação Geográfica no estudo da interação genótipo-ambiente em cana-de-açúcar.
O objetivo deste estudo foi identificar fatores ambientais com efeito significativo sobre a interação genótipo x ambiente em cana-de-açúcar e produzir mapas temáticos de adaptabilidade produtiva para o estado de Goiás, integrando modelos de regressão fatorial e dados do Sistema de Informação Geográfica. O estudo foi baseado na produtividade de açúcar total recuperável obtida de ensaios conduzidos em nove localidades, no ano agrícola de 2011/2012.Evento online
Modelling of genotype by environment interaction to improve the recommendation of sugarcane cultivars for the state of Goiás, Brazil.
The objective of this work was to identify environmental factors with significant effects on the genotype by environment interaction (GEI) of sugarcane, and to generate thematic maps yield adaptability of genotypes for the state of Goiás, Brazil, through the integrated use of factorial regression models and the geographic information system (GIS). The study was based on the yield of recoverable sugar (YRS) from cultivar field trials carried out in nine locations. Fourteen environmental factors were used, out of which 11 were divided into 10 crop growth phases, totaling 113 environmental covariates (ECs). The selection of ECs was done by successive simple linear regressions, and the respective genotypic sensitivity coefficients were used to generate adaptability maps. Approximately 57% of the GEI effects were related to the covariates longitude, average temperature at crop germination phase, and maximum temperature at the beginning of the phase of greatest growth. For YRS, the RB034128 and RB034021 clones show specific yield adaptations, and the RB034045 cultivar can share the growing area with the RB867515 check cultivar
Fluxo de gases (CH4, N2O e CO2) em área de cana-de-açúcar sem queima irrigada com efluente de esgoto tratado.
O reuso agrícola de efluentes de esgoto tratado (EET) é uma prática de interesse ambiental e econômico, contudo, seu impacto em solos brasileiros ainda é pouco conhecido. Dentre as culturas com características favoráveis para o reuso agrícola, a cana-de-açúcar se destaca, por possuir elevado potencial para o cultivo irrigado e pela crescente expansão, incentivada pela produção de biocombustíveis. Com o objetivo de avaliar o efeito da irrigação da cana-de açúcar (Saccharum officinarum) com efluente de esgoto tratado sobre a emissão de gases (CH4, N2O e CO2) relacionados com o efeito estufa, foi conduzido um experimento em Piracicaba, SP, em área próxima a uma à estação de tratamento de esgoto (ETE). A avaliação das emissões foi conduzida 4 meses após a rebrota, referente à segunda soca da cana-de-açúcar. Não foram observados efeitos do manejo da irrigação com EET nos fluxos de CH4 e N2O a partir do solo. A irrigação com EET promoveu um aumento linear nas emissões de CO2 nas lâminas com 100% da Evapotranspiração da cultura (Etc) e de 200% da Etc, elevaram as emissões de CO2 em 33 e 146% pelo solo cultivado com cana de açúcar
Ciclagem interna de nitrogênio em solo cultivado com capim Tifton-85 e irrigado com esgoto tratado.
O objetivo desta pesquisa foi avaliar o efeito da irrigação com água, efluente secundário de nitrogenada na produção vegetal, na quantidade de liteira depositada e nos conteúdos de matéria orgânica particulada em uma pastagem de capim-Bermuda tifton 85. O delineamento experimental foi composto de quatro blocos ao acaso e seis tratamentos: SI (controle, sem fertilização e sem irrigação); W100, irrigação com água e 100% da dose de fertilizante nitrogenado recomendado; E0, E33, E66 e E100, irrigado com esgoto tratado e adição de 0, 33; 66 e 100% da dose recomendada, respectivamente. Amostras de efluente/água, solo, produção vegetal e liteira foram coletadas no período de abril a outubro de 2007. A maior oferta de N nos tratamentos E66, E100 e A100, através da fertilização, irrigação e ciclagem interna pela Bermuda Tifton 85 em período pós chuvas (abril?junho de 2007). No sistema avaliado, a deposição de liteira foi mais diferentes tratamentos. Maiores conteúdos médios de MOP foram observados no solo dos tratamentos irrigados e fertilizados.1 CD-ROM
Morphological and molecular characterization of two trematode worms in the gastropod Asolene pulchella (Anton, 1859)
Asolene pulchella (Anton, 1859) Asolene pulchella (Caenogastropoda, Ampullariidae) is a native gastropod from La Plata River. In a previous study we reported the presence of parasite forms of Trematoda (Plathyhelminthes) in the digestive gland of adult snails from Regatas Lake (Buenos Aires). In this work identified two parasites with a morphological and molecular approach. The digestive gland of A. pulchella showed a large amount of larval forms (sporocysts and rediae) with internal cercariae in diverse degree of development.Facultad de Ciencias Naturales y Muse
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