2,689 research outputs found
Gravity with extra dimensions and dark matter interpretation: Phenomenological example via Miyamoto-Nagai galaxy
A configuration whose density profile coincides with the Newtonian potential
for spiral galaxies is constructed from a 4D isotropic metric plus extra
dimensional components. A Miyamoto-Nagai ansatz is used to solve Einstein
equations. The stable rotation curves of such system are computed and, without
fitting techniques, we recover with accuracy the observational data for flat or
not asymptotically flat galaxy rotation curves. The density profiles are
reconstructed and compared to that obtained from the Newtonian potential.Comment: 10 pages, 10 figures, submitted to Brazilian Journal of Physic
Pneumatosis Coli Treated with Metronidazole and Hyperbaric Oxygen Therapy: A Successful Case
A pneumatose intestinal, caracterizada pela presença de gás na parede do cólon, é uma condição incomum com um espectro de apresentação variável. Pode ser idiopática ou secundária a outras doenças. A tomografia computorizada é o método de diagnóstico com maior sensibilidade. Na ausência de sinais e sintomas sugestivos de complicações, como a perfuração e a peritonite, a pneumatose intestinal pode ser tratada de forma conservadora. Apresenta-se o caso de uma mulher de 59 anos com pneumatose cólica secundária a teratoma ovárico benigno. Após a cirurgia, manteve-se sintomática e foi tratada com sucesso com metronidazol e oxigenoterapia hiperbárica
Exopolysaccharide production by Helicobacter pylori
Helicobacter pylori is a widespread Gram-negative bacterium that infects the
stomach of humans leading to the onset of several gastric disorders, such as, gastritis,
gastric ulcers, and cancers. Studies from developing countries with low socioeconomic
status and poor management of the drinking water suggest that it may serve as an
environmental reservoir of H. pylori and therefore contribute to human infection.
It has been reported that H. pylori has the ability to form microbial consortia
embedded by a highly hydrated exopolysaccharidic matrix (biofilms) on surfaces
exposed to water. The enhanced protection provided to microbial cells by the
exopolysaccharides (EPS) brings added concerns about the possibility of H. pylori
being transmitted through drinking water. H. pylori EPS as been reported to be
composed mainly by Gal:Glc:GlcN in a proportion of 1.0:2.1:7.0, respectively (Stark et
al., 1999).
The present work brings about microscopical evidences of the capability of H.
pilory to form free swimming bacterial aggregates and biofilms when submitted to
nutrient depletion and hydrodynamic stress. Evidences that H. pylori aggregation is an
exopolysaccharidic mediated phenomena both in planktonic and sessile states are also
showed. Ethanol fractioning of the material recovered from these aggregates revealed an
EPS composed of Gal:Glc:GlcN in a proportion of 1.0:0.4:1.6 respectively. A further
structural detail about this EPS is under progress
Evidences of exopolysaccharide production by Helicobacter pylori submitted to hydrodynamic stress
Helicobacter pylori is a widespread Gram-negative bacterium that infects the
stomach of humans leading to the onset of several gastric disorders, such as
gastritis, gastric ulcers, and cancers. The transmission of H. pylori remains
unclear but two different pathways have been suggested: faecal-oral and oraloral.
It has been reported that H. pylori has the ability to incorporate in
biofilms formed on water-exposed surfaces thus providing a route of
infection. On the other hand, a polysaccharide-containing biofilm has been
observed at the air-liquid interface when H. pylori is grown in a glass
fermenter1. Because exopolysaccharides (EPS) play a determinant role in
bacterial adhesion by conferring protection against adverse conditions such
as starvation and environmental aggressions, EPS production would be
expected to be higher if the bacterium is exposed to water. In this work the
capability of H. pylori to produce EPS when exposed to water and under
hydrodynamic stress has been evaluated. H. pylori was inoculated in
autoclaved distilled water and allowed to stand under gentle stirring at room
temperature. The significant and continuous increase in the sugar content
192 hours after inoculation suggests the production of exopolysaccharides.
This evidence is reinforced by epiflourescence microscopical observation of
the bacteria stained with DAPI (4,6-diamidino-2-phenylindole) that revealed
the presence of bacterial aggregates 318 hours after inoculation
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A Data-Driven Feature Extraction Method for Enhanced Phonocardiogram Segmentation
In this work, we present a method to extract features from heart sound signals in order to enhance segmentation performance. The approach is data-driven, since the way features are extracted from the recorded signals is adapted to the data itself. The proposed method is based on the extraction of delay vectors, which are modeled with Gaussian mixture model priors, and an information-theoretic dimensionality reduction step which aims to maximize discrimination between delay vectors in different segments of the heart sound signal. We test our approach with heart sounds from the publicly available PhysioNet dataset showing an average F1 score of 92.6% in detecting S1 and S2 sounds
Depositional sequences and ammonoid assemblages in the upper Cenomanian-lower Santonian of the Iberian Peninsula (Spain and Portugal)
A clear relationship exists between eustatic sea-level rises and falls recorded as cyclical depositional sequences and ammonite faunas during the Cenomanian-Santonian in the Iberian and West Portuguese basins. Most of the faunal turnovers correlate with stratigraphic intervals related to marine transgressions, maximum flooding of the shelf (locally associated to anoxic events), and marine regressions. Specifically, within each depositional sequence, three distinct and identical events of morphological change occur, involving ammonoids belonging to different groups. Transgressive sediments are characterized by moderately ornamented, inflated and evolute morphologies, which are replaced by smooth, involute and compressed oxycones (the most hydrodynamic shells) during maximum flooding (and to a lesser extent at the early highstand) of the sequences. The latter morphologies in turn are replaced by coarsely ornamented and evolute shells during late highstands. We conclude that ammonoid faunal analysis can be used to trace sea-level changes and provides an additional tool for sequence stratigraphy
He II 4686 emission from the massive binary system in Car: constraints to the orbital elements and the nature of the periodic minima
{\eta} Carinae is an extremely massive binary system in which rapid spectrum
variations occur near periastron. Most notably, near periastron the He II
line increases rapidly in strength, drops to a minimum value,
then increases briefly before fading away. To understand this behavior, we
conducted an intense spectroscopic monitoring of the He II
emission line across the 2014.6 periastron passage using ground- and
space-based telescopes. Comparison with previous data confirmed the overall
repeatability of EW(He II ), the line radial velocities, and the
timing of the minimum, though the strongest peak was systematically larger in
2014 than in 2009 by 26%. The EW(He II ) variations, combined
with other measurements, yield an orbital period d. The observed
variability of the EW(He II ) was reproduced by a model in which
the line flux primarily arises at the apex of the wind-wind collision and
scales inversely with the square of the stellar separation, if we account for
the excess emission as the companion star plunges into the hot inner layers of
the primary's atmosphere, and including absorption from the disturbed primary
wind between the source and the observer. This model constrains the orbital
inclination to -, and the longitude of periastron to
-. It also suggests that periastron passage occurred on
d. Our model also reproduced EW(He II )
variations from a polar view of the primary star as determined from the
observed He II emission scattered off the Homunculus nebula.Comment: The article contains 23 pages and 17 figures. It has been accepted
for publication in Ap
Desempenho de hibridos de abóboras e morangas avaliadas no Distrito Federal.
O presente trabalho teve como objetivo avaliar o desempenho agronômico de oito hibridos experimentais de abóboras e morangas em Brasília, DF.Suplemento. Edição dos Anais do 53 Congresso Brasileiro de Olericultura, jul. 2014
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