19,514 research outputs found
Binarity in Cool Asymptotic Giant Branch Stars: A Galex Search for Ultraviolet Excesse
The search for binarity in AGB stars is of critical importance for our
understanding of how planetary nebulae acquire the dazzling variety of
aspherical shapes which characterises this class. However, detecting binary
companions in such stars has been severely hampered due to their extreme
luminosities and pulsations. We have carried out a small imaging survey of AGB
stars in ultraviolet light (using GALEX) where these cool objects are very
faint, in order to search for hotter companions. We report the discovery of
significant far-ultraviolet excesses towards nine of these stars. The
far-ultraviolet excess most likely results either directly from the presence of
a hot binary companion, or indirectly from a hot accretion disk around the
companion.Comment: revised for Astrophysical Journa
Reducing sample variance: halo biasing, non-linearity and stochasticity
Comparing clustering of differently biased tracers of the dark matter
distribution offers the opportunity to reduce the cosmic variance error in the
measurement of certain cosmological parameters. We develop a formalism that
includes bias non-linearities and stochasticity. Our formalism is general
enough that can be used to optimise survey design and tracers selection and
optimally split (or combine) tracers to minimise the error on the
cosmologically interesting quantities. Our approach generalises the one
presented by McDonald & Seljak (2009) of circumventing sample variance in the
measurement of . We analyse how the bias, the noise,
the non-linearity and stochasticity affect the measurements of and explore
in which signal-to-noise regime it is significantly advantageous to split a
galaxy sample in two differently-biased tracers. We use N-body simulations to
find realistic values for the parameters describing the bias properties of dark
matter haloes of different masses and their number density.
We find that, even if dark matter haloes could be used as tracers and
selected in an idealised way, for realistic haloes, the sample variance limit
can be reduced only by up to a factor .
This would still correspond to the gain from a three times larger survey volume
if the two tracers were not to be split. Before any practical application one
should bear in mind that these findings apply to dark matter haloes as tracers,
while realistic surveys would select galaxies: the galaxy-host halo relation is
likely to introduce extra stochasticity, which may reduce the gain further.Comment: 21 pages, 13 figures. Published version in MNRA
Projeto Rondon no município de Caridade – CE: avaliação dos resultados obtidos com as feiras da saúde
Trabalho apresentado no II Congresso Nacional do PROJETO RONDON, realizado em Florianópolis, SC, no período de 23 a 25 de setembro de 2015 - Universidade Federal de Santa Catarina.A Organização Mundial de Saúde (OMS) classifica as condições de saúde em agudas e crônicas, tendo a Hipertensão Arterial Sistêmica (HAS) e o Diabetes Mellitus (DM) como condições crônico-degenerativas de saúde. Assim, tais patologias recebem atenção especial do sistema de saúde, haja vista a alta prevalência das complicações cardiovasculares, cerebrovasculares, nefrológicas e visuais oriundas dessas doenças. Nesse sentido, essas afecções e seus agravos necessitam de ações efetivas de promoção e prevenção da saúde. A Feira da Saúde foi uma das oficinas do Centro Universitário de Patos de Minas – UNIPAM durante o Projeto Rondon de Janeiro/2015 - Operação Mandacaru em Caridade - CE. As ações basearam-se na realização de um circuito de atendimento, no qual o paciente foi acolhido e devidamente identificado e a seguir, foram coletadas e registradas, em uma ficha própria desenvolvida para a feira, informações de saúde desses indivíduos. Ao final do circuito, cada pessoa atendida apresentou esse instrumento a um rondonista. Após a avaliação dos dados encontrados na ficha, o membro da equipe dialogou com o paciente, dando ênfase em orientações que, de acordo com as evidências científicas, reduzem a mortalidade, como uma alimentação saudável, a prática regular de atividade física, a redução ou abolição do consumo de bebidas alcóolicas, tabaco e outras drogas e a utilização correta de medicamentos para o controle da Hipertensão Arterial e do Diabetes Mellitus. Ao longo da realização do Projeto Rondon no município, esta oficina foi desenvolvida quatro vezes, em Caridade e nos distritos de São Domingos e Ipueira dos Gomes, ultrapassando o número de 250 indivíduos atendidos. Desses, 135 tiveram suas fichas sorteadas aleatoriamente para a avaliação do perfil dos pacientes acolhidos nas feiras de saúde. Dentre os resultados obtidos, perceberam-se nitidamente os hábitos de vida desfavoráveis para o aparecimento e a progressão das doenças crônicas, sendo relevante citar o percentual elevado de pacientes com sobrepeso e obesidade e o sedentarismo, este último observado através dos mais de 80% dos pacientes que não praticavam nenhuma atividade física. Portanto, acredita-se que as Feiras da Saúde foram de suma importância para a conscientização da população desse município para o autocuidado orientado através de hábitos de vida saudáveis
The redshift and broad band spectral energy distribution of NRAO 150
Context. NRAO 150 is one of the brightest radio and mm AGN sources on the
northern sky. It has been revealed as an interesting source where to study
extreme relativistic jet phenomena. However, its cosmological distance has not
been reported so far, because of its optical faintness produced by strong
Galactic extinction.
Aims. Aiming at measuring the redshift of NRAO 150, and hence to start making
possible quantitative studies from the source.
Methods. We have conducted spectroscopic and photometric observations of the
source in the near-IR, as well as in the optical.
Results. All such observations have been successful in detecting the source.
The near-IR spectroscopic observations reveal strong H and H
emission lines from which the cosmological redshift of NRAO 150
() has been determined for the first time. We classify the
source as a flat-spectrum radio-loud quasar, for which we estimate a large
super-massive black-hole mass . After
extinction correction, the new near-IR and optical data have revealed a
high-luminosity continuum-emission excess in the optical (peaking at
\,\AA, rest frame) that we attribute to thermal emission from the
accretion disk for which we estimate a high accretion rate, \,% of the
Eddington limit.
Conclusions. Comparison of these source properties, and its broad-band
spectral-energy distribution, with those of Fermi blazars allow us to predict
that NRAO 150 is among the most powerful blazars, and hence a high luminosity
-although not detected yet- -ray emitter.Comment: 8 pages, 4 figure
Biomimetic cork-based CeO2 ecoceramics for hydrogen generation using concentrated solar energy
Naturally occurring and sustainable materials can be used as a template to create biomimetic/biomorphic ceramics, known as Ecoceramics (environmentally conscious ceramics). In this work, cork was chosen as template to produce novel ceria (CeO2) ecoceramics, for applications in water splitting for H2 production via direct concentrated solar thermochemical fuel production (TCFP). The cork powder was pyrolised at 900 °C and the resulting carbon skeleton was infiltrated with an aqueous CeO2 precursor, and then heated at 1000 °C for 2 h to produce the ecoceramic. The cellular structure of the cork was maintained, with hexagonal cell dimensions of 20-30 μm in diameter, but the grains were nanoscale at ≤100 nm. XRD data confirmed that CeO2 was the only crystalline phase obtained. An important feature was that, while the rectangular side walls were maintained to hold the three-dimensionally ordered macroporous (3DOM) cellular cork structure, the rear hexagonal walls were pierced repeatedly through the structure, unlike in the original cork structure, which will allow gasses such as H2 to permeate well into the structure, greatly increasing the reactive area available for catalysis. The next step will be to test the capabilities of both the regular, porous 3DOM structure and the nanoscale grains for thermochemical water splitting to produce hydrogen under direct concentrated solar energy
A systematic review of breast milk microbiota composition and the evidence for transfer to and colonisation of the infant gut
The intestinal microbiota plays a major role in infant health and development. However, the role of the breastmilk
microbiota in infant gut colonisation remains unclear. A systematic review was performed to evaluate the composition
of the breastmilk microbiota and evidence for transfer to/colonisation of the infant gut. Searches were performed
using PUBMED, OVID, LILACS and PROQUEST from inception until 18th March 2020 with a PUBMED update
to December 2021. 88 full texts were evaluated before final critique based on study power, sample contamination
avoidance, storage, purification process, DNA extraction/analysis, and consideration of maternal health and other
potential confounders. Risk of skin contamination was reduced mainly by breast cleaning and rejecting the first milk
drops. Sample storage, DNA extraction and bioinformatics varied. Several studies stored samples under conditions
that may selectively impact bacterial DNA preservation, others used preculture reducing reliability. Only 15 studies,
with acceptable sample size, handling, extraction, and bacterial analysis, considered transfer of bacteria to the
infant. Three reported bacterial transfer from infant to breastmilk. Despite consistent evidence for the breastmilk
microbiota, and recent studies using improved methods to investigate factors affecting its composition, few studies
adequately considered transfer to the infant gut providing very little evidence for effective impact on gut colonisation
Determining the regimes of cold and warm inflation in the susy hybrid model
The SUSY hybrid inflation model is found to dissipate radiation during the
inflationary period. Analysis is made of parameter regimes in which these
dissipative effects are significant. The scalar spectral index, its running,
and the tensor-scalar ratio are computed in the entire parameter range of the
model. A clear prediction for strong dissipative warm inflation is found for
n_S-1 \simeq 0.98 and a low tensor-scalar ratio much below 10^{-6}. The strong
dissipative warm inflation regime also is found to have no \eta-problem and
with the field amplitude much below the Planck scale. As will be discussed,
this has important theoretical implications in permitting a much wider variety
of SUGRA extensions to the basic model.Comment: paragraph added at the end of section V; references added; accepted
for publication in Phys. Rev.
Diversidad genética de Pinus pinaster en la Península Ibérica: correlación entre isoenzimas y caracteres cuantitativos
The estimation of genetic diversity using molecular markers is a major component of genetic conservation programs. However, molecular data are only weakly correlated with adaptive variation, which seriously limits the value of molecular information for guiding conservation policies. In this paper, we used allozyme markers to analyse the distribution of gene diversity in the native range of Pinus pinaster Ait. in the Iberian Peninsula, including seven marginal populations close to the Mediterranean Basin. Then, the variability of three quantitative traits (total height, stem form and survival) was computed using data from a multisite provenance test in central Spain and the two data sets were compared. Within the general pattern of variation, marginal populations presented levels of diversity closely related to those of nearby central populations, clearly suggesting that historical factors were more important than actual population sizes in determining levels of observed diversity. A weak but nevertheless significant correlation between allozymes and quantitative variability was found in maritime pine. Environmental gradients, as measured by geographic variables, are suggested to have selective effects on quantitative traits and to influence effective population size, which might explain the weak correlation found between allozyme and adaptive variability.Uno de los principales componentes de los programas de conservación genética es el uso de marcadores moleculares para la estimación de la diversidad genética. A pesar de ello, la variación observada en marcadores moleculares está débilmente correlacionada con la variación adaptativa, lo que limita seriamente la aplicación de estos estudios en el desarrollo de políticas de conservación. En este trabajo, se compara la distribución de la diversidad genética de Pinus pinaster Ait. en la Península Ibérica obtenida con marcadores moleculares (isoenzimas) y caracteres cuantitativos (altura, forma del fuste y supervivencia). El estudio incluye siete poblaciones marginales. Éstas, muestran valores de diversidad similares a los de poblaciones centrales próximas lo que sugiere una gran importancia de los procesos históricos regionales frente a efectos relacionados con el tamaño efectivo poblacional. La correlación de los marcadores moleculares utilizados con los caracteres cuantitativos medidos en los ensayos de campo es débil, aunque significativa. Esta correlación podría explicarse considerando efectos selectivos en respuesta a gradientes ambientales que afectan a su vez el tamaño efectivo de las poblaciones
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Estimation of Groundwater Recharge to the Gulf Coast Aquifer in Texas, USA
Quantifying groundwater recharge is essential for managing water resources in aquifers. The objective of this study was to quantify spatial variability in recharge in the outcrop zones of the Gulf Coast aquifer in Texas.
Regional recharge was estimated using the chloride mass balance approach applied to groundwater chloride data from the TWDB database in 10,530 wells, which represented the most recent samples from wells located in the region. Regional groundwater recharge was also estimated using streamflow hydrograph separation in 59 watersheds using USGS unregulated gage data. Recharge was also estimated by applying the chloride mass balance approach to unsaturated zone chloride data from 27 boreholes that represented a range of precipitation, land use, and soil texture settings in the central and southern Gulf Coast regions.
Groundwater chloride concentrations generally decrease from the southern to the northern Gulf Coast, qualitatively indicating increasing recharge in this direction with increasing precipitation. Ratios of chloride to bromide are less than 150 to 200 throughout most of the Gulf Coast, suggesting a predominantly meteoric source for groundwater chloride.
Recharge rates based on the chloride mass balance approach range from less than 0.1 in/yr in the south to 10 in/yr in the north, correlated with increasing precipitation. Streamflow ranges from ephemeral in parts of the southern Gulf Coast to perennial throughout the rest of the Gulf Coast based on flow duration curves. Hydrograph separation using Base-Flow Index (BFI) showed that recharge increased from south to north, similar to increases in recharge based on groundwater chloride data.
Unsaturated zone profiles show high local variability in chloride concentrations, with mean concentrations below the root zone ranging from 7 to 10,200 mg/L. Resultant percolation rates below the root zone based on the chloride mass balance approach range from less than 0.1 to 6.8 in/yr. In some areas, variations in percolation rates are related to differences in soil texture, whereas in other regions, they are related to differences in land use. However, there is no systematic variation in percolation rates throughout the region, unlike the trends in recharge with regional precipitation from groundwater chloride data and stream hydrograph separation.
Recharge rates based on groundwater chloride data can be considered to provide a conservative lower bound on actual recharge because many processes can add chloride to the system, resulting in lower recharge rates whereas there are no processes that can remove chloride from the system in the Gulf Coast. Stream hydrograph separation provides recharge rates in contributing basins that do not cover the entire Gulf Coast region. Recharge estimates from the chloride mass balance applied to groundwater and perennial stream hydrograph separation are highly correlated (r = 0.96), and differences between these two sets of recharge estimates can be used to evaluate uncertainties in recharge rates in contributing basins to the stream gages.
Recharge rates from groundwater chloride and streamflow hydrograph separation can be used to provide a range of recharge rates for future groundwater models of the Gulf Coast aquifer.Bureau of Economic Geolog
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