Electromagnetic structure and weak decay of meson K in a light-front QCD-inspired model

The kaon electromagnetic (e.m.) form factor is reviewed considering a light-front constituent quark model. In this approach, it is discussed the relevance of the quark-antiquark pair terms for the full covariance of the e.m. current. It is also verified, by considering a QCD dynamical model, that a good agreement with experimental data can be obtained for the kaon weak decay constant once a probability of about 80% of the valence component is taken into account.

Direct observation of the strange b baryon Xi(-)(b)

We report the first direct observation of the strange b baryon Xi(-)(b)(Xi) over bar (+)(b)). We reconstruct the decay Xi(-)(b)-->J/psi Xi(-), with J/psi-->mu(+)mu(-), and Xi(-)-->Lambda pi(-)-->p pi(-)pi(-) in p (p) over bar collisions at root s = 1.96 TeV. Using 1.3 fb(-1) of data collected by the D0 detector, we observe 15.2 +/- 4.4(stat)(-0.4)(+1.9)(syst) Xi(-)(b) candidates at a mass of 5.774 +/- 0.011(stat) +/- 0.015(syst) GeV. The significance of the observed signal is 5.5 sigma, equivalent to a probability of 3.3 x 10(-8) of it arising from a background fluctuation. Normalizing to the decay Lambda(b)-->J/psi Lambda, we measure the relative rate sigma(Xi(-)(b))xB(Xi(-)(b)-->J/psi Xi)/ sigma(Lambda(b))xB(Lambda(b)-->J/psi Lambda) = 0.28 +/- 0.09(stat)(-0.08)(+0.09)(syst).

SEMICLASSICAL VIOLATION of THE EQUIVALENCE PRINCIPLE IN THE GRAVITATIONAL LENSES REALM

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Model-independent measurement of t-channel single top quark production in p(p)over-bar collisions at,root s=1.96 TeV

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

A New Boson with a Mass of 125 GeV Observed with the CMS Experiment at the Large Hadron Collider

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Observation of the Doubly Strange b Baryon Omega(-)(b)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Characterization of multiple reflections and phase space properties for a periodically corrugated waveguide

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Evaluation of nine microsatellite loci and misidentification paternity frequency in a population of Gyr breed bovines

Erros de identificação de paternidade são prejudiciais por reduzir o ganho genético anual e comprometer um programa eficiente de melhoramento genético. O objetivo principal deste trabalho foi avaliar o potencial de uso de nove microssatélites em testes de paternidade e investigar a freqüência de erro de identificação de famílias de um rebanho de animais da raça Gir. No experimento foram utilizadas amostras de sangue de quarenta famílias (touro/ vaca/ bezerro) de animais da raça Gir, Puros de Origem e registrados na Associação Brasileira dos Criadores de Zebu (ABCZ). A maior parte dos microssatélites avaliados neste trabalho são recomendados, para Testes de Paternidade em bovinos, pela Sociedade Internacional de Genética Animal (ISAG). As regiões microssatélites TGLA122, TGLA126, BM1824, BMS2533, SPS115, ETH3, ETH10, ETH225 e POTCHA foram amplificadas por meio da técnica de PCR. Os produtos da amplificação foram separados por eletroforese em gel de poliacrilamida desnaturante. A partir dos dados obtidos foram calculadas as freqüências alélicas, diversidade gênica, conteúdo de polimorfismo informativo e probabilidade de exclusão para cada microssatélite. Também foram calculadas as freqüências genotípicas, heterozigosidade, probabilidade de exclusão combinada e probabilidade de Paternidade nas famílias consideradas. A probabilidade de exclusão combinada para todos os microssatélites estudados foi de 0,9789. Os resultados dos testes de paternidade acusaram erro de identificação em onze das 40 famílias estudadas, ou seja, 27,5% da amostra. A probabilidade de paternidade variou entre 0,8691 e 0,9999, com valor médio de 0,9512.

The role of chain scission and chain branching in high density polyethylene during thermo-mechanical degradation

The mechanical and thermo-oxidative degradation of high density polyethylene (HDPE) was measured in a twin-screw extruder using various processing conditions. Two types of HDPE, Phillips and Ziegler-Natta, having different levels of terminal vinyl unsaturation were analysed. Mild screw profiles, having mainly conveying elements, have short mean residence times then profiles with kneading discs and left hand elements. Carbonyl and traps-vinylene group concentrations increased, whereas vinyl group concentration decreased with number of extrusions. Higher temperature profiles intensified these effects. The thermo-mechanical degradation mechanism begins with chain scission in the longer chains due to their higher probability of entanglements. These macroradicals then react with the vinyl terminal unsaturations of other chains producing chain branching. Shorter chains are more mobile, not suffering scission but instead are used for grafting the macroradicals, increasing the molecular weight. Increase in the levels of extrusion temperature, shear and vinyl end groups content facilitates the thermo-mechanical degradation reducing the amount of both, longer chains via chain scission and shorter chains via chain branching, narrowing the polydispersity. Phillips HDPE produces a higher level of chain branching than does the Ziegler-Natta type. (C) 2004 Elsevier Ltd. All rights reserved.

Hyperlipidemia as a risk factor of renal allograft function impairment

In this study, the graft outcome in renal allograft recipients with [high cholesterol group (HCG), n = 30] or without [normal cholesterol group (NCG), n = 42] hypercholesterolemia and with [high triglyceride group (HTG), n = 33] or without [normal triglyceride group (NTG), n = 36] hypertriglyceridemia were prospectively compared. At 6 months post-transplantation, no significant difference was observed between the groups (NTG compared with HTG, and NCG compared with HCG) regarding age, presence of arterial hypertension, kind of donor (living related or cadaveric), immunosuppressive therapy, number of rejection episodes per patient, frequency of patients with acute cellular rejection, prevalence of patients with diabetes mellitus or proteinuria > 3 g/24 h, and mean serum creatinine. The probability of doubling serum creatinine during follow-up was statistically different between NTG and HTG (12 months: NTG = 0.03, HTG = 0.15; 36 months: NTG = 0.08, HTG = 0.33; 60 months: NTG = 0.08, HTG = 0.48; and 120 months: NTG = 0.18, HTG = 0.48), but not between NCG and HCG (12 months: NCG = 0.05, HCG = 0.13; 36 months: NCG = 0.13, HCG = 0.24; 60 months: NCG = 0.19, HCG = 0.31; 84 months: NCG = 0.27, HCG = 0.31). There was no significant difference in actuarial graft survival between HCG and NCG or between NTG and HTG. Hypertriglyceridemia, but not hypercholesterolemia, was associated with loss of graft function.

On the scattering of comets by a planet

In this paper, numerical simulations are made, using the three-dimensional restricted three-body problem as the mathematical model, to calculate the effects of a swing-by with the planet Saturn in the orbit of a comet. To show the results, the orbit of the comet is classified in four groups: elliptic direct, elliptic retrograde, hyperbolic direct and hyperbolic retrograde. Then, the modification in the orbit of the comet due to the close approach is shown in plots that specify from which group the comet's orbit is coming and to which group it is going. Several families of orbits are found and shown in detail. An analysis about the trends as parameters (position and velocity at the periapse) vary is performed and the influence of each of them is shown and explained. The result is a collection of maps that describe the evolution of the trajectory of the comet due to the close approach. Those maps can be used to estimate the probability of some events, like the capture or escape of a comet. An example of this technique is shown in the paper. (C) 2005 COSPAR. Published by Elsevier Ltd. All rights reserved.

DISTRIBUTION OF THE NUMBER OF EURYTREMA SP EGGS PER GRAM OF FECES IN NATURALLY INFECTED CATTLE

Eurytrema sp. egg counts (epg) in the feces of naturally infected cattle were performed and the technique employed showed 94.2% probability of detecting positive cases of the infection with a single examination independently of the host parasite burden. It was also demonstrated that the epg of Eurytrema sp. follows a negative binomial distribution model and is characterized by its small magnitude.

A Bayesian approach for assessing the stability of genotypes

Several statistical models can be used for assessing genotype X environment interaction (GEI) and studying genotypic stability. The objectives of this research were to show how (i) to use Bayesian methodology for computing Shukla's phenotypic stability variance and (ii) to incorporate prior information on the parameters for better estimation. Potato [Solanum tuberosum subsp. andigenum (Juz. & Bukasov) Hawkes], wheat (Triticum aestivum L.), and maize (Zea mays L.) multi environment trials (MET) were used for illustrating the application of the Bayes paradigm. The potato trial included 15 genotypes, but prior information for just three genotypes was used. The wheat trial used prior information on all 10 genotypes included in the trial, whereas for the maize trial, noninformative priors for the nine genotypes was used. Concerning the posterior distribution of the genotypic means, the maize MET with 20 sites gave less disperse posterior distributions of the genotypic means than did the posterior distribution of the genotypic means of the other METs, which included fewer environments. The Bayesian approach allows use of other statistical strategies such as the normal truncated distribution (used in this study). When analyzing grain yield, a lower bound of zero and an upper bound set by the researcher's experience can be used. The Bayesian paradigm offers plant breeders the possibility of computing the probability of a genotype being the best performer. The results of this study show that although some genotypes may have a very low probability of being the best in all sites, they have a relatively good chance of being among the five highest yielding genotypes.

Evaluation of Philips and Ziegler-Natta high-density polyethylene degradation during processing in an internal mixer using the chain scission and branching distribution function analysis

The oxidative and thermo-mechanical degradation of HDPE was studied during processing in an internal mixer under two conditions: totally and partially filled chambers, which provides lower and higher concentrations of oxygen, respectively. Two types of HDPEs, Phillips and Ziegler-Natta, having different levels of terminal vinyl unsaturations were analyzed. Materials were processed at 160, 200, and 240 degrees C. Standard rheograrns using a partially filled chamber showed that the torque is much more unstable in comparison to a totally filled chamber which provides an environment depleted of oxygen. Carbonyl and transvinylene group concentrations increased, whereas vinyl group concentration decreased with temperature and oxygen availability. Average number of chain scission and branching (n(s)) was calculated from MWD curves and its plotting versus functional groups' concentration showed that chain scission or branching takes place depending upon oxygen content and vinyl groups' consumption. Chain scission and branching distribution function (CSBDF) values showed that longer chains undergo chain scission easier than shorter ones due to their higher probability of entanglements. This yields macroradicals that react with the vinyl terminal unsaturations of other chains producing chain branching. Shorter chains are more mobile, not suffering scission but instead are used for grafting the macroradicals, increasing the molecular weight. Increase in the oxygen concentration, temperature, and vinyl end groups' content facilitates the thermo-mechanical degradation reducing the amount of both, longer chains via chain scission and shorter chains via chain branching, narrowing the polydispersity. Phillips HDPE produces a higher level of chain branching than the Ziegler-Natta's type at the same processing condition. (c) 2006 Elsevier Ltd. All rights reserved.

Conformational analyses and docking studies of a series of 5-nitrofuran- and 5-nitrothiophen-semicarbazone derivatives in three possible binding sites of trypanothione and glutathione reductases

To explore three possible binding sites of trypanothione and glutathione reductase, namely, the active, the dimer interface and the coenzyme NADPH binding site, a series of eight compounds, nitrofurans and nitrothiophenes derivatives, were docked, using their crystallographic and modeled conformations. Docking results showed that, for both families and both enzymes, compounds are more likely to bind in the interface site, even though there is some probability of binding in the active site. These studies are in agreement with experimental data, which suggest that these class of compounds can act either as uncompetitive or mixed type inhibitors, and also with the finding that there is an alpha-helix which connects the active with the interface site, thus allowing charge transference between them. (c) 2005 Elsevier B.V. All rights reserved.