Self-similar and charged spheres in the diffusion approximation

We study spherical, charged and self--similar distributions of matter in the diffusion approximation. We propose a simple, dynamic but physically meaningful solution. For such a solution we obtain a model in which the distribution becomes static and changes to dust. The collapse is halted with damped mass oscillations about the absolute value of the total charge.Comment: 15 pages, 7 figure

Exact correlation functions of Bethe lattice spin models in external fields

We develop a transfer matrix method to compute exactly the spin-spin correlation functions of Bethe lattice spin models in the external magnetic field h and for any temperature T. We first compute the correlation function for the most general spin - S Ising model, which contains all possible single-ion and nearest-neighbor pair interactions. This general spin - S Ising model includes the spin-1/2 simple Ising model and the Blume-Emery-Griffiths (BEG) model as special cases. From the spin-spin correlation functions, we obtain functions of correlation length for the simple Ising model and BEG model, which show interesting scaling and divergent behavior as T approaches the critical temperature. Our method to compute exact spin-spin correlation functions may be applied to other Ising-type models on Bethe and Bethe-like lattices.Comment: 19 page

Cluster Hybrid Monte Carlo Simulation Algorithms

We show that addition of Metropolis single spin-flips to the Wolff cluster flipping Monte Carlo procedure leads to a dramatic {\bf increase} in performance for the spin-1/2 Ising model. We also show that adding Wolff cluster flipping to the Metropolis or heat bath algorithms in systems where just cluster flipping is not immediately obvious (such as the spin-3/2 Ising model) can substantially {\bf reduce} the statistical errors of the simulations. A further advantage of these methods is that systematic errors introduced by the use of imperfect random number generation may be largely healed by hybridizing single spin-flips with cluster flipping.Comment: 16 pages, 10 figure

Produtividade de milho sob doses e parcelamentos de N em solo com alto teor de matérioa orgânica no agreste sergipano.

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Infection process and host defense responses in compatible and incompatible interactions between Cowpea (Vigna unguiculata) and Colletotrichum gloeosporioides.

The infection process of Colletotrichum gloeosporioides was examined by light microscopy on two cowpea genotypes, BR 3 Tracuateua and TE 97-411. In the susceptible genotype BR 3 Tracuateua, the pathogen acted as an intracellular hemibiotroph. Invasion of cowpea primary leaves occurred preferentially through the leaf epidermal cells by penetration tubes that emerged from appressoria. The penetration tube swelled within 48 h to form a spherical infection vesicle inside the epidermal cell in a biotrophic interaction. Subsequently, it became multilobed and multiseptated. By 4 d after inoculation, one or more large primary hyphae emerged from the lateral lobes and grew intracellularly and further colonized several adjacent epidermal host cells, characterizing the necrotrophic phase of infection. Primary leaves of the resistant cowpea genotype, TE 97-411, showed enhanced penetration resistance to C. gloeosporioides associated with higher epidermal H2O2 accumulation beneath appressoria and primary germ tubes, papilla formation, and increased phenylalanine ammonia-lyase activity, possibly related to accumulation of phenolic compounds and host cell wall lignification. Macroscopic examination of the primary leaves revealed the presence of shrunken necrotic lesions characteristic of anthracnose in infected BR 3 Tracuateua, whereas in the genotype TE 97-411, cell death was also observed but only in a reduced percentage of the infection sites. In summary, the results obtained in this study suggested that TE 97-411 is the resistant genotype to C. gloeosporioides compared with BR 3 Tracuateua because it developed more effective defense responses against the establishment of the pathogen

Role of Antioxidant Enzymes, Hydrogen Peroxide and PRProteins in the Compatible and Incompatible Interactions of Cowpea (Vigna unguiculata) Genotypes with the Fungus Colletotrichum gloeosporioides.

This work was conducted to measured the time-course activities and evaluate the possible roles of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and hydrogen peroxide (H2 O2 ), and the pathogenesis-related proteins (PR-proteins), peroxidase (POX), β-1,3-glucanase (GLU) and chitinase (CHI), in the resistant (TE97) and susceptible (BR3) cowpea genotypes in response to C. gloeosporioides infection

Rubella seroprevalence among primary and pre- primary school pupils at Moi's Bridge location, Uasin Gishu District, Kenya

<p>Abstract</p> <p>Background</p> <p>Rubella is an infectious and generally mild childhood viral disease. The disease is of public health importance because infection acquired during early pregnancy often results in foetal abnormalities that are classified as congenital rubella syndrome (CRS). The burden of rubella infection in most developing countries in not well documented because of limited epidemiological data. However, availability of an effective vaccine has made it necessary to have all the countries with no routine vaccination schedule to evaluate the burden of disease in order to make informed decisions on rubella vaccination and strategy. To address this gap we conducted a study to determine age-specific rubella seroprevalence rates and related risk factors among primary and pre-primary school children in Uasin Gishu district, Moi's Bridge location of Kenya.</p> <p>Methods</p> <p>Subjects of the study were 498 pupils from seven primary schools aged 4–20 years. Questionnaire surveys with blood sampling were conducted between January to July 2005. Samples were tested for rubella specific IgG antibody using ELISA test kit (Enzygnost^®Behring, Germany).</p> <p>Results</p> <p>Overall, rubella seropositivity rate was 80% and it increased with age from 59% (among ages 4–6 years) to 94% (ages 14–20 years). Multivariate logistic regression analysis model, showed that age of child and ownership of a television set which is a proxy measure of socio-economic status of family were significantly associated with rubella seropositivity. The odds of rubella seropositivity in a child older than 13 years was more than that in children younger than 7 years (OR = 3.8 95% CI 2.56–5.78). The odds of rubella seropositivity in a child whose family did not own a television set was 3 times higher than that of child whose family owned a set (OR 3.06, 95% CI 1.17–7.97).</p> <p>Conclusion</p> <p>The study provides important and highly useful information on rubella age specific seroprevalence rates in Kenya. Advancing age was found to be associated with increased risk of rubella. Low socio-economic factors suggest an increased risk of infection in certain categories of society, and control measures need to target this. Overall, the findings can also be used by policy makers to model introduction of routine rubella vaccination in the country and also other developing countries facing similar challenges. More than half of the children got infected in pre-primary and efforts to control rubella should target pre-school children. These data provides pre-vaccination information that can be used to guide immunization strategy as well as to determine success of an immunization programme.</p

Nonadiabatic charged spherical gravitational collapse

We present a complete set of the equations and matching conditions required for the description of physically meaningful charged, dissipative, spherically symmetric gravitational collapse with shear. Dissipation is described with both free-streaming and diffusion approximations. The effects of viscosity are also taken into account. The roles of different terms in the dynamical equation are analyzed in detail. The dynamical equation is coupled to a causal transport equation in the context of Israel-Stewart theory. The decrease of the inertial mass density of the fluid, by a factor which depends on its internal thermodynamic state, is reobtained, with the viscosity terms included. In accordance with the equivalence principle, the same decrease factor is obtained for the gravitational force term. The effect of the electric charge on the relation between the Weyl tensor and the inhomogeneity of energy density is discussed.Comment: 23 pages, Latex. To appear in Phys. Rev. D. Some references correcte

Host defense responses restricts the growth of the fungus Colletotrichum lindemuthianum in cowpea, TE 97 411-1E resistant genotype.

Cowpea is the main subsistence crop in the semiarid North-east of Brazil. However, very few is known concerning to its defense mechanisms against fungi. The objective of this present work was to evaluate the infection strategies of the hemibiotrophic fungi Colletotrichum lindemuthianum and the associated cytological defense responses of two cowpea genotypes, TE 97-411-1E (resistant) and BR 3 Tracuateua (susceptible). The infection process of the fungi in both genotypes occurred preferentially through the leaf epidermal cells by penetration tubes emerged from appressoria. The resistant cowpea genotype, TE 97-411-1E, showed enhanced penetration resistance to C. lindemuthianum associated with higher epidermal H2O2 accumulation, papilla formation, and increase in phenylalanine ammonialyase activity, possibly related to accumulation of phenolic compounds and host cell wall lignification. Macroscopic examination of the primary leaves revealed the presence of shrunken necrotic lesions characteristic of anthracnose in infected BR 3 Tracuateua, whereas in TE 97-411-1E cell death was also observed but only in a reduced percentage of the infection sites. In summary the results obtained in the present study suggested that TE 97-411-1E genotype is more resistant to C. lindemuthianum compared to BR 3 Tracuateua, as it developed more effective defense responses against the establishment of the pathogen