4,013 research outputs found
Domain wall description of superconductivity
In the present work we shall address the issue of electrical conductivity in
superconductors in the perspective of superconducting domain wall solutions in
the realm of field theory. We take our set up made out of a dynamical complex
scalar field coupled to gauge field to be responsible for superconductivity and
an extra scalar real field that plays the role of superconducting domain walls.
The temperature of the system is interpreted through the fact that the soliton
following accelerating orbits is a Rindler observer experiencing a thermal
bath.Comment: 9 pages, 5 figures, Latex. Version to appear in PL
Cosmic voids in modified gravity scenarios
Modified gravity (MG) theories aim to reproduce the observed acceleration of
the Universe by reducing the dark sector while simultaneously recovering
General Relativity (GR) within dense environments. Void studies appear to be a
suitable scenario to search for imprints of alternative gravity models on
cosmological scales. Voids cover an interesting range of density scales where
screening mechanisms fade out, which reaches from a density contrast close to their centers to close to their
boundaries. We present an analysis of the level of distinction between GR and
two modified gravity theories, the Hu-Sawicki and the symmetron theory.
This study relies on the abundance, linear bias, and density profile of voids
detected in n-body cosmological simulations. We define voids as connected
regions made up of the union of spheres with a {\it \textup{mean}} density
given by , but disconnected from any
other voids. We find that the height of void walls is considerably affected by
the gravitational theory, such that it increases for stronger gravity
modifications. Finally, we show that at the level of dark matter n-body
simulations, our constraints allow us to distinguish between GR and MG models
with and . Differences of best-fit values for
MG parameters that are derived independently from multiple void probes may
indicate an incorrect MG model. This serves as an important consistency check.Comment: 15 pages, 12 figure
As transformações quanto aos principais usos da floresta na comunidade Santa Maria, assentamento olho d'água II, município de Moju, estado do Pará.
As reflexões apresentadas foram resultantes de uma pesquisa realizada na comunidade Santa Maria, espacializada no Assentamento Olho D’Água II, município de Moju, Nordeste Paraense, durante os meses de maio e julho de 2008. O objetivo do artigo é analisar as transformações vivenciadas por um grupo de agricultores quanto ao uso da floresta, mais especificamente as associadas à obtenção de caças e a realização das roças, após a mudança da condição de uso comum (posseiros) para o uso privado (assentados) a partir da implantação do assentamento em 2002. A metodologia constou de abordagens qualitativas e quantitativas, tendo como principais procedimentos: revisão de literatura, entrevistas estruturadas e semiestruturadas, observações e levantamento de dados secundários. Os resultados apontam que ocorreram transformações importantes nas dinâmicas de uso dos recursos com intensificação do cultivo de roças e diminuição da obtenção de caças devido a grande dificuldade em obtê-las, em decorrência das novas condições de acesso privado à terra, como também, por causa do aumento demográfico cuja demanda por caça supera em muito a oferta dos animais, fato que impulsiona ainda mais a especialização no uso das roças que constituem-se na principal fonte de renda e alimento para a reprodução familiar
The pinewood nematode, Bursaphelenchus xylophilus, in Madeira Island
The environmental conditions in Madeira Island are favorable
for the presence and dissemination of the pinewood
nematode (PWN), Bursaphelenchus xylophilus. Five hundred
Pinus pinaster wood samples were collected in several
forest areas and PWN was detected in 22.8 % of the
samples. Bursaphelenchus xylophilus isolates from Madeira
Island displayed the species-specific diagnostic characters.
A morphological variation in the female tail terminus was
detected. In most females, the tail presented a broadly
rounded terminus and, occasionally, a digitate terminus with
a terminal nipple-like extension resembling a mucro. PCR
ITS-RFLP analysis revealed that Madeira Island isolates
exhibited patterns specific to the species B. xylophilus and
similar to virulent isolates. Amplified ITS regions were
further sequenced and no genetic diversity was found for
this genomic region among 17 Portuguese isolates (Madeira
Island and Continental Portugal). Phylogenetic analysis
revealed that Portuguese isolates grouped with isolates from
China, Korea and one isolate from Japa
On virialization with dark energy
We review the inclusion of dark energy into the formalism of spherical
collapse, and the virialization of a two-component system, made of matter and
dark energy. We compare two approaches in previous studies. The first assumes
that only the matter component virializes, e.g. as in the case of a classic
cosmological constant. The second approach allows the full system to virialize
as a whole. We show that the two approaches give fundamentally different
results for the final state of the system. This might be a signature
discriminating between the classic cosmological constant which cannot virialize
and a dynamical dark energy mimicking a cosmological constant. This signature
is independent of the measured value of the equation of state. An additional
issue which we address is energy non-conservation of the system, which
originates from the homogeneity assumption for the dark energy. We propose a
way to take this energy loss into account.Comment: 15 pages, 5 figures. Accepted for publication in JCA
Alcohol consumption among patients with hepatitis B infection in northern Portugal considering gender and hepatitis B virus genotype differences
Alcohol. 2010 Mar;44(2):149-56. Epub 2010 Jan 29.
Alcohol consumption among patients with hepatitis B infection in northern Portugal considering gender and hepatitis B virus genotype differences.
Mota A, Guedes F, Areias J, Pinho L, Cardoso MF.
SourceInstituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Portugal.
Abstract
Alcohol abuse is an important public health problem. In Portugal with a population of 10 millions of inhabitants, there are around 10% of alcoholics or excessive alcohol drinkers and 1% of chronically infected patients with hepatitis B virus (HBV). To examine the characteristics of patients with higher levels of alcohol consumption and to investigate the association between alcohol consumption and liver damage a total of 298 chronically infected individuals, with HBV genotyped and submitted to liver biopsy, were classified with Child's grading and separated by habits of alcohol intake, less and greater than 20g/day. No significant differences were observed about genotype but genotypes A and D were predominant in both of them. A higher percentage of males (P<.001) were observed in the group with alcohol intake above 20g/day, as well a lower proportion of patients with HBeAg negativity (P< or =.035). In this group, biochemistry parameters, such as alanine aminotransferase (P=.006), aspartate aminotransferase (P=.001), gamma-glutamyl transferase (P<.001) were elevated in a significantly higher proportion than in the other group. The analysis of hematological parameters showed significantly lower values of platelets (P=.042) and mean corpuscular volume (P<.001) and significantly higher values of prothrombin time (P<.001) in the group with higher levels of alcohol consumption. The characteristics of biopsy (P<.001) and Child-Phug's classification (P=.002) revealed more severe results in this group. Logistic regression showed a positive association between liver damage and alcohol intake, increasing with age. In female patients, a strong positive association between alcohol intake and liver damage was also found (odds ratio: 9.379; 95% confidence interval: 0.859-468.422; P = .037); however, the most severe cases were only observed in women older than 45 years. In patients with HBV infection, alcohol is associated with a more severe liver disease. No evidence was found concerning association with HBV genotype.
2010 Elsevier Inc. All rights reserved
Surface Analysis Of Alumina Ceramic Exposed To Shock Waves Produced By Plasma Expander
Material surface treatment by plasma expander is relatively recent. Plasma expander is based on the inverse pinch effect. The shock waves produced by plasma expander may also promote modifications in ceramic materials exposed to the expander. These modifications are mainly made by ablation phenomenon. This work was intended to verify the shock wave effects on the ionic ceramic samples with high dielectric constant. The alumina ceramic samples were formed by both uniaxial and isostatic pressing methods and sintered at 1650 degrees C. They were also produced with addition 0.15 wt% of MgO in order to obtain a high densification. The ceramic samples were divided in groups and exposed to 700, 1000 and 1440 pulses during 20 min. These pulses were generated by nitrogen plasma expander at 13.0 Pa and 6 kV. After plasma exposure, there was an increase in roughness parameter values of Al2O3 ceramic surface. The treatment by plasma expander did not modify the hydrophilic characteristic of the alumina ceramic samples. The results of hardness test presented no significant changes on hardness mean values.59
Epidemiological study of genotypes of hepatitis B virus in northerm Portugal
ed Virol. 2009 Jul;81(7):1170-6.
Epidemiological study of genotypes of hepatitis B virus in northern Portugal.
Mota A, Guedes F, Areias J, Pinho L, Cardoso MF.
SourceInstituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal.
Abstract
While the overall prevalence of hepatitis B virus (HBV) infection in Portugal is around 1%, there are no published studies examining HBV genotypes in this country. This study aimed to survey HBV genotypes in the northern Portugal and to examine the possible associations between genotypes and gender, viral transmission routes, viral markers, viral load, and biochemical tests of liver function. The study sample consists of 340 patients with HBV infection of whom 42.9% were women. Tests were carried out for HBV genotypes and biochemical liver function while demographic information, including alcohol intake, was obtained from the patient files. The results indicate the predominance of genotype D (60.3%) and genotype A (31.5%). Intrafamilial transmission was predominant in female patients, while males were infected in equal proportions by perinatal, sexual, and intrafamilial transmission. Absence of HBeAg was found in a significantly smaller proportion of female patients with genotype D as compared to A (56.6% vs. 82.1%, P = 0.028). High viral load was associated significantly and independently with genotype D and HBeAg. Both alanine and aspartate aminotransferases (ALT and AST) were associated with gender and HBeAg. Thus, genotypes A and D were found to be the most prevalent in the north of Portugal. Patients infected with genotype D had higher levels of HBV DNA. HBeAg was associated with genotype D, viral load, and ALT and AST
Transformação dos principais usos da floresta no município de Moju, nordeste paraense.
As reflexões aqui apresentadas foram resultantes de uma pesquisa realizada na comunidade Santa Maria, uma das comunidades componentes do Assentamento Olho D?Água II, município de Moju, estado do Pará. O objetivo do artigo é analisar as transformações vivenciadas por um grupo de agricultores quanto ao uso da floresta, mais especificamente as associadas à obtenção de caças e à realização das roças, após a mudança da condição de uso comum (posseiros) para o uso privado (assentados) a partir da implantação do assentamento em 2002. Os resultados apontam que ocorreram transformações nas dinâmicas de uso dos recursos com a intensificação do cultivo de roças e a diminuição da obtenção de caças devido à grande dificuldade em obtê-las, em decorrência das novas condições de acesso privado à terra e ao aumento demográfico cuja demanda por caça supera em muito a oferta dos animais
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