941 resultados para marine community dynamics


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Empirical data indicate that the so-called ""Buddhism of yellow color"" that is predominantly associated with Japanese ""immigrant"" Buddhism, is constantly in decline in terms of ""explicit"" adherents. After some methodological observations, this article gives an overview of the relevant statistical data. The last part discusses possible reasons for these negative dynamics, referring to causes within Buddhist institutions, the ethnic community, and at the level of the individual.

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It is a generally acknowledged fact that the dynamics of frontier advance deeply influenced the broad experience of American post colonial societies. The colonization, which started most from the east boundaries of the continent, appropriated and gradually transformed the American territories from east to west. The advance, initially represented by the arrival of the European settlers, went on to become an important trace of that society which did not come to know any physical limits of a restricted territory. However, despite the common identity granted by these territorial dynamics, the later developments and consequences seem to have shaped differently the Northern representatives from their Southern counterparts. In addition, the interpretation of these facts bore in each of these regions different meanings and traits.

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Background: The Brazilian population is mainly descendant from European colonizers, Africans and Native Americans. Some Afro-descendants lived in small isolated communities since the slavery period. The epidemiological status of HBV infection in Quilombos communities from northeast of Brazil remains unknown. The aim of this study was to characterize the HBV genotypes circulating inside a Quilombo isolated community from Maranhao State, Brazil. Methods: Seventy-two samples from Frechal Quilombo community at Maranhao were collected. All serum samples were screened by enzyme-linked immunosorbent assays for the presence of hepatitis B surface antigen ( HBsAg). HBsAg positive samples were submitted to DNA extraction and a fragment of 1306 bp partially comprising HBsAg and polymerase coding regions (S/POL) was amplified by nested PCR and its nucleotide sequence was determined. Viral isolates were genotyped by phylogenetic analysis using reference sequences from each genotype obtained from GenBank (n = 320). Sequences were aligned using Muscle software and edited in the SE-AL software. Bayesian phylogenetic analyses were conducted using Markov Chain Monte Carlo (MCMC) method to obtain the MCC tree using BEAST v.1.5.3. Results: Of the 72 individuals, 9 (12.5%) were HBsAg-positive and 4 of them were successfully sequenced for the 1306 bp fragment. All these samples were genotype A1 and grouped together with other sequences reported from Brazil. Conclusions: The present study represents the first report on the HBV genotypes characterization of this community in the Maranhao state in Brazil where a high HBsAg frequency was found. In this study, we reported a high frequency of HBV infection and the exclusive presence of subgenotype A1 in an Afro-descendent community in the Maranhao State, Brazil.

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Background: To determine the prevalence of diabetes mellitus (DM) and impaired glucose tolerance (IGT) in a rural community (Bengo) of Angola. Methods: A random sample of 421 subjects aged 30 to 69 years (30% men and 70% women) was selected from three villages of Bengo province. This cross-sectional home survey was conducted using a sampling design of stage conglomerates. First, clinical and anthropometric data were obtained and fasting capillary glucose level was determined. Subjects who screened positive (fasting capillary glucose >= 100 mg/dl and < 200 mg/dl) and each sixth consecutive subject who screened negative (fasting capillary glucose < 100 mg/dl) were submitted to the second phase of survey, consisting of the 75 g oral glucose tolerance test. Data was analyzed by the use of SAS statistical software. Results: The prevalence rates of diabetes mellitus and IGT were 2.8% and 8.1%, respectively. The age group with the highest prevalence of diabetes was 60 to 69 years (42%). Impaired glucose tolerance prevalence was 38% in the 40 to 49 year age group and it increased with age, considering that the 50 to 59 and 60 to 69 year age groups as a whole represent 50% of all subjects with impaired glucose tolerance. The prevalence of diabetes mellitus did not differ significantly between men (3.2%) and women (2.7%) (p = 0.47). On the other hand, the prevalence of impaired glucose tolerance among women showed almost twice that found in men (9.1% vs. 5.6%, respectively). Overweight was present in 66.7% of the individuals with diabetes mellitus and 26.5% of individuals with impaired glucose tolerance showed overweight or obesity. Conclusions: Although the prevalence of diabetes mellitus was low, the prevalence of impaired glucose tolerance is considered to be within an intermediary range, suggesting a future increase in the frequency of diabetes in this population.

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Previous population dynamics data, generated for Amblyomma parvum Aragao and Aniblyomma cajennense (Fabricius) in Argentina and southeastern Brazil, have indicated that these ticks complete I generation per year, with larvae predominating in autumn, nymphs in winter, and mostly adults during spring and summer. The present study reports population dynamics data for free-living Amblyomma spp. ticks in northern Brazil (Amazon forest, latitude 10 degrees S, 63 degrees W), and for Amblyomma spp. ticks collected oil birds in Southeastern Brazil (latitude 23 degrees S, 45 degrees W). In northern Brazil, adult ticks predominated from mid-spring to mid-autumn, larvae predominated in early winter, and nymphs from mid-winter to mid-spring. Seven Amblyomma spp. were identified, although A. cajannense predominated in I of the 2 sites sampled. In southeastern Brazil, larval infestations on birds peaked in autumn, followed by a nymphal infestation peak in late winter. At least 32% and 75% of these larvae and nymphs, respectively, were identified as Amblyomma longirostre (Koch). Similar to previous work, the present study showed that Amblyomma spp. larvae and nymphs predominated during autumn-winter months, and mostly adults during spring-summer months, a pattern compatible with 1 genration/yr, even at latitude 10 degrees S in northern Brazil.

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Aims. We present a dynamical analysis of the galaxy cluster Abell 1942 based on a set of 128 velocities obtained at the European Southern Observatory. Methods. Data on individual galaxies are presented and the accuracy of the determined velocities as some properties of the cluster are discussed. We have also made use of publicly available Chandra X-ray data. Results. We obtained an improved mean redshift value z = 0.22513 +/- 0.0008 and velocity dispersion sigma = 908(139)(+147) km s(-1). Our analysis indicates that inside a radius of similar to 1.5 h(70)(-1) Mpc (similar to 7 arcmin) the cluster is well relaxed, without any remarkable features and the X-ray emission traces the galaxy distribution fairly well. Two possible optical substructures are seen at similar to 5 arcmin from the centre in the northwest and the southwest directions, but are not confirmed by the velocity field. These clumps are, however, kinematically bound to the main structure of Abell 1942. X-ray spectroscopic analysis of Chandra data resulted in a temperature kT = 5.5+/-0.5 keV and metal abundance Z = 0.33 +/- 0.15 Z(circle dot). The velocity dispersion corresponding to this temperature using the T(X-sigma) scaling relation is in good agreement with the measured galaxy velocities. Our photometric redshift analysis suggests that the weak lensing signal observed to the south of the cluster and previously attributed to a ""dark clump"" is produced by background sources, possibly distributed as a filamentary structure.

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We discuss the dynamics of the Universe within the framework of the massive graviton cold dark matter scenario (MGCDM) in which gravitons are geometrically treated as massive particles. In this modified gravity theory, the main effect of the gravitons is to alter the density evolution of the cold dark matter component in such a way that the Universe evolves to an accelerating expanding regime, as presently observed. Tight constraints on the main cosmological parameters of the MGCDM model are derived by performing a joint likelihood analysis involving the recent supernovae type Ia data, the cosmic microwave background shift parameter, and the baryonic acoustic oscillations as traced by the Sloan Digital Sky Survey red luminous galaxies. The linear evolution of small density fluctuations is also analyzed in detail. It is found that the growth factor of the MGCDM model is slightly different (similar to 1-4%) from the one provided by the conventional flat Lambda CDM cosmology. The growth rate of clustering predicted by MGCDM and Lambda CDM models are confronted to the observations and the corresponding best fit values of the growth index (gamma) are also determined. By using the expectations of realistic future x-ray and Sunyaev-Zeldovich cluster surveys we derive the dark matter halo mass function and the corresponding redshift distribution of cluster-size halos for the MGCDM model. Finally, we also show that the Hubble flow differences between the MGCDM and the Lambda CDM models provide a halo redshift distribution departing significantly from the those predicted by other dark energy models. These results suggest that the MGCDM model can observationally be distinguished from Lambda CDM and also from a large number of dark energy models recently proposed in the literature.

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Hepatitis C virus (HCV) infects 170 million people worldwide, and is a major public health problem in Brazil, where over 1% of the population may be infected and where multiple viral genotypes co-circulate. Chronically infected individuals are both the source of transmission to others and are at risk for HCV-related diseases, such as liver cancer and cirrhosis. Before the adoption of anti-HCV control measures in blood banks, this virus was mainly transmitted via blood transfusion. Today, needle sharing among injecting drug users is the most common form of HCV transmission. Of particular importance is that HCV prevalence is growing in non-risk groups. Since there is no vaccine against HCV, it is important to determine the factors that control viral transmission in order to develop more efficient control measures. However, despite the health costs associated with HCV, the factors that determine the spread of virus at the epidemiological scale are often poorly understood. Here, we sequenced partial NS5b gene sequences sampled from blood samples collected from 591 patients in Sao Paulo state, Brazil. We show that different viral genotypes entered Sao Paulo at different times, grew at different rates, and are associated with different age groups and risk behaviors. In particular, subtype 1b is older and grew more slowly than subtypes 1a and 3a, and is associated with multiple age classes. In contrast, subtypes 1a and 3b are associated with younger people infected more recently, possibly with higher rates of sexual transmission. The transmission dynamics of HCV in Sao Paulo therefore vary by subtype and are determined by a combination of age, risk exposure and underlying social network. We conclude that social factors may play a key role in determining the rate and pattern of HCV spread, and should influence future intervention policies.

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This article focuses on the identification of the number of paths with different lengths between pairs of nodes in complex networks and how these paths can be used for characterization of topological properties of theoretical and real-world complex networks. This analysis revealed that the number of paths can provide a better discrimination of network models than traditional network measurements. In addition, the analysis of real-world networks suggests that the long-range connectivity tends to be limited in these networks and may be strongly related to network growth and organization.

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Noise is an intrinsic feature of population dynamics and plays a crucial role in oscillations called phase-forgetting quasicycles by converting damped into sustained oscillations. This function of noise becomes evident when considering Langevin equations whose deterministic part yields only damped oscillations. We formulate here a consistent and systematic approach to population dynamics, leading to a Fokker-Planck equation and the associate Langevin equations in accordance with this conceptual framework, founded on stochastic lattice-gas models that describe spatially structured predator-prey systems. Langevin equations in the population densities and predator-prey pair density are derived in two stages. First, a birth-and-death stochastic process in the space of prey and predator numbers and predator-prey pair number is obtained by a contraction method that reduces the degrees of freedom. Second, a van Kampen expansion in the inverse of system size is then performed to get the Fokker-Planck equation. We also study the time correlation function, the asymptotic behavior of which is used to characterize the transition from the cyclic coexistence of species to the ordinary coexistence.

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The dynamic polarizability and optical absorption spectrum of liquid water in the 6-15 eV energy range are investigated by a sequential molecular dynamics (MD)/quantum mechanical approach. The MD simulations are based on a polarizable model for liquid water. Calculation of electronic properties relies on time-dependent density functional and equation-of-motion coupled-cluster theories. Results for the dynamic polarizability, Cauchy moments, S(-2), S(-4), S(-6), and dielectric properties of liquid water are reported. The theoretical predictions for the optical absorption spectrum of liquid water are in good agreement with experimental information.

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The electronic properties of liquid ammonia are investigated by a sequential molecular dynamics/quantum mechanics approach. Quantum mechanics calculations for the liquid phase are based on a reparametrized hybrid exchange-correlation functional that reproduces the electronic properties of ammonia clusters [(NH(3))(n); n=1-5]. For these small clusters, electron binding energies based on Green's function or electron propagator theory, coupled cluster with single, double, and perturbative triple excitations, and density functional theory (DFT) are compared. Reparametrized DFT results for the dipole moment, electron binding energies, and electronic density of states of liquid ammonia are reported. The calculated average dipole moment of liquid ammonia (2.05 +/- 0.09 D) corresponds to an increase of 27% compared to the gas phase value and it is 0.23 D above a prediction based on a polarizable model of liquid ammonia [Deng , J. Chem. Phys. 100, 7590 (1994)]. Our estimate for the ionization potential of liquid ammonia is 9.74 +/- 0.73 eV, which is approximately 1.0 eV below the gas phase value for the isolated molecule. The theoretical vertical electron affinity of liquid ammonia is predicted as 0.16 +/- 0.22 eV, in good agreement with the experimental result for the location of the bottom of the conduction band (-V(0)=0.2 eV). Vertical ionization potentials and electron affinities correlate with the total dipole moment of ammonia aggregates. (c) 2008 American Institute of Physics.

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We model interface formation by metal deposition on the conjugated polymer poly-para-phenylene vinylene, studying direct aluminum and layered aluminum-calcium structures Al/PPV and Al/Ca/PPV. To do that we use classical molecular dynamics simulations, checked by ab initio density-functional theory calculations, for selected relevant configurations. We find that Al not only migrates easily into the film, with a strong charge transfer to the neighboring chains, but also promotes rearrangement of the polymer in the interfacial region to the hexagonal structure. On the other hand, our results indicate that a thin Ca layer is sufficient to protect the film and maintain a well-defined metal/polymer interface, and that also a thin Al capping layer may protect the whole from environmental degradation.

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We have performed ab initio molecular dynamics simulations to generate an atomic structure model of amorphous hafnium oxide (a-HfO(2)) via a melt-and-quench scheme. This structure is analyzed via bond-angle and partial pair distribution functions. These results give a Hf-O average nearest-neighbor distance of 2.2 angstrom, which should be compared to the bulk value, which ranges from 1.96 to 2.54 angstrom. We have also investigated the neutral O vacancy and a substitutional Si impurity for various sites, as well as the amorphous phase of Hf(1-x)Si(x)O(2) for x=0.25, 0375, and 0.5.

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NiCl(2)-4SC(NH(2))(2) (known as DTN) is a spin-1 material with a strong single-ion anisotropy that is regarded as a new candidate for Bose-Einstein condensation (BEC) of spin degrees of freedom. We present a systematic study of the low-energy excitation spectrum of DTN in the field-induced magnetically ordered phase by means of high-field electron spin resonance measurements at temperatures down to 0.45 K. We argue that two gapped modes observed in the experiment can be consistently interpreted within a four-sublattice antiferromagnet model with a finite interaction between two tetragonal subsystems and unbroken axial symmetry. The latter is crucial for the interpretation of the field-induced ordering in DTN in terms of BEC.