O fator de compressibilidade (Z) de gás natural é utilizado em vários cálculos na engenharia de petróleo (avaliação de formações, perda de carga em tubulações, gradiente de pressão em poços de gás, cálculos de balanço de massa, medição de gás, compressão e processamento de gás). As fontes mais comuns de valores de Z são medições experimentais, caras e demoradas. Essa propriedade também é estimada por correlações empíricas, modelos baseados no princípio dos estados correspondentes ou equações de estado (EOS). Foram avaliadas as capacidades das EOS de Soave-Redlich-Kwong (SRK), Peng-Robinson (PR), Patel-Teja (PT), Patel-Teja-Valderrama (PTV), Schmidt-Wenzel (SW), Lawal-Lake-Silberberg (LLS) e AGA-8 para previsão desta propriedade em aproximadamente 2200 pontos de dados experimentais. Estes pontos foram divididos em quatro grupos: Grupo 1 (Presença de frações C7+, Grupo 2 (temperaturas inferiores a 258,15 K), Grupo 3 (pressões superiores a 10000 kPa) e Grupo 4 (pressões inferiores a 10000 kPa). Os cálculos utilizando as equações de estado sob diferentes esquemas de previsão de coeficientes binários de interação foram cuidadosamente investigados. Os resultados sugerem que a EOS AGA-8 apresenta os menores erros para pressões de até 70000 kPa. Entretanto, observou-se uma tendência de aumento nos desvios médios absolutos em função das concentrações de CO2 e H2S. As EOS PTV e a EOS SW são capazes de predizer o fator de compressibilidade (Z) com desvios médios absolutos entre os valores calculados e experimentais com precisão satisfatória para a maioria das aplicações, para uma variada faixa de temperatura e pressão. Este estudo também apresenta uma avaliação de 224 métodos de cálculo de Z onde foram utilizadas 8 correlações combinadas com 4 regras de mistura para estimativa de temperaturas e pressões pseudorreduzidas das amostras, junto com 7 métodos de caracterização das propriedades críticas da fração C7+, quando presente na composição do gás. Em função dos resultados são sugeridas, para diferentes tipos de sistemas, as melhores combinações de correlações com regras de mistura capazes de predizer fatores de compressibilidade (Z) com os menores erros absolutos médios relativos

Functional records were collected in 584 heifers born between 2001 and 2009 in the Murteira Grave herd of the Brava breed. These records were collected on the farm, in conditions known as “tenta”, which intends to simulate a bullfight and serve as the basis for selection in this breed. The traits recorded were physical type (trapío), bravery (bravura) and ability for bullfight (toureabilidade), which were scored on a scale from 1 to 10. Additionally, a pedigree file was built for the herd, based on the records existing in the Associação Portuguesa de Criadores de Touros de Lide. These records covered the period 1970- 2010, and included 4631 animals. The demographic analysis indicates that the Murteira Grave herd has been able to maintain inbreeding at very moderate levels (0.019±0.019), mostly by introducing animals from other herds periodically. This has resulted in a well-structured population, with a diversified representation of several founders and ancestors. Taken together, the results of our study indicate that the tenta traits evaluated have high levels of genetic variability (h2 =0.24 a 0.45), which provide the foundations for a good selection program with appropriate response. On the other hand, the genetic correlations among the traits selected for are positive, indicating that the improvement in one of the traits will not cause a deterioration in the others, and that benefits will result from the joint selection for the different traits.

The reduction of resinous species in Portuguese forest areas has caused constraints to wood industry supplies. Portugal represents the extreme southwest of Scots pine (Pinus sylvestris) natural distribution and large gaps exist in the knowledge of its wood-quality characteristics. Understanding the relationship between these traits is important for recognizing which combination of wood properties is the most suitable for specific uses. To address these questions, we assessed wood-quality traits, namely, wood-density components (microdensitometric analysis), chemical composition (NIR spectrometry) and mechanical properties (bending tests) of wood samples collected at five representative forest sites in Portugal. Our results showed that Portuguese Pinus sylvestris has good radial growth and denser wood, higher extractive content and higher stiffness and strength than northern European provenances. The lignin content was within the range attributed to softwoods. Among the Portuguese stands, trees growing at lower-altitude sites exhibited denser wood and higher mechanical properties, while trees from high-elevations showed higher amounts of lignin. Ring density was more strongly correlated with earlywood than latewood density. A negative, non-significant correlation was found between ring density and width, supporting the assumption that the higher radial growth (ring width) does not negatively affect wood quality (density). In general, chemical properties had a weak relationship with physical and mechanical properties (MOE and MOR). Both mechanical traits were positively correlated with density and growth components, supporting the assumption that trees with high radial growth do not exhibit poorer mechanical performances

Just like in many other fields of research, sport sciences use statistics to infer about the associations between variables. For example, aiming to examine the relationship between squat jump with sprint running velocity has brought several experiments, demonstrating a strong to very strong association between variables (e.g., Sleivert & Taingahue, 2004; Wisløff et al., 2004). From there on, there have been researchers proposing training programs for improving the squat jump, and consequently, the sprint running (e.g., Chelly et al., 2009). While this example seems unanimous, other emerging ideas may be questionable.

We analyze the effect of the tensor force and other components of the nucleon-nucleon interaction on the nuclear symmetry energy and its density dependence by using the Hellmann–Feynman theorem. The analysis is performed within the microscopic Brueckner–Hartree–Fock approach using the Argonne V18 potential plus a Urbana IX three-nucleon force. Our results show that the potential part of the nuclear Hamiltonian, and in particular its tensor component, gives the largest contribution to the symmetry energy. The decomposition of the symmetry energy into a kinetic part and a potential energy part provides physical insight on the correlated nature of the system, indicating that pure neutron matter is less correlated than symmetric nuclear matter.

ABSTRACT A total of 6593 weight records collected from 796 male and female Anglo-Nubian goats aged up to 130 days, offspring from 29 sires and 225 dams, were used to compare models and estimate genetic parameters throughout the growth curve by applying random regression models. Direct and maternal additive genetic effects and direct and maternal permanent environmental effects were included as random in the models. The contemporary groups were included as fixed effects and goat age at kidding was included as a covariable (linear and quadratic). The choice of the best model was based on the AIC, BIC and AICc criteria. Variance estimates of the four random effects increased as the animals aged. Direct heritability (h2) rose from 0.13 to 0.40 with age, whereas maternal heritability showed a low value. Genetic correlations of weight between closer ages were high. The most suitable random regression model to compare the fitting of random effects was that which employed the Legendre polynomials of quadratic order with homogeneous variance (3333-1).

Three production systems for sheep (Low - L, Medium - M and High - H technology), with increasing technological levels, were studied under conditions in the Center-west of Brazil, to determine economic weights and selection indices of important traits. Receipts and costs were simulated using an economic simulator to calculate the structure of the operational costs. Only characteristics that were responsible for more than 10% of the profit were studied, which included: number of weaned lambs, food consumption (ewe and lamb), weight of carcass and weight of female lambs sold for reproduction. Regardless of the index used (profitability or yield) or system (L, M or H), the economic weights are larger for the number of lambs weaned per ewe. With improvement in the technology used within the production system (H to L) the importance of this trait becomes less important. Lamb growth increased and weight of female for slaughter decreased in importance in higher technology systems. Changes in herd structure had little influence on economic values, whereas (co)variances were important sources of change in selection indices.

Abstract In this work we study the influence of the Sobradinho dam construction on daily streamflow of São Francisco River, Brasil, by analyzing long-range correlations in magnitude and sign time series obtained from streamflow anomalies, using the Detrended Fluctuation Analysis (DFA) method. The magnitude series relates to the nonlinear properties of the original time series, while the sign series relates to the linear properties. The streamflow data recorded during the period 1929-2009, were divided in the periods pre-construction (1929 to 1972) and post-construction (1980 to 2009) of Sobradinho dam and analyzed for small scales (less than 1 year) and for large scales (more than 1 year). In post-construction of Sobradinho dam, DFA-exponents of magnitude series increased at small scales (0.895 to 1.013) and at large scales (0.371 to 0.619) indicating that the memory associated with nonlinear components becames stronger. For sign series, the DFA-exponent increased at small scales (0.596 to 0.692) indicating stronger persistence of flow increments direction, and decreased at large scales (0.381 to 0.259) indicating stronger anti-persistence (positive increments are more likely to be followed by negative increments and vice versa). These results provide new evidence on the hydrological changes in the São Francisco River caused by human activities.

This study aimed to evaluate the relationship among traits related to yield and nutritive value of alfalfa genotypes grown under deficit and full irrigation conditions. Seventy-seven alfalfa genotypes were evaluated in two different cuts, the first one with full irrigation, and the second, with water deficit. A randomized block design with three replications was used. The evaluated traits were vigor, plant height, dry matter biomass, stem-to-leaf ratio, dry matter percentage, leaf and stem protein contents, in vitro dry matter digestibility, neutral detergent fiber, acid detergent fiber, and lignin. Significant interaction between genotypes and environments was reported for vigor, plant height, and lignin. The correlation between traits and path analysis of dry matter biomass was performed for each cut, aiming to identify auxiliary traits for indirect selection. Water availability did not alter the phenotypic and genotypic correlations, only their magnitudes. Regardless of the environment, plant height is one of the most promising traits for the selection of alfalfa genotypes with higher dry matter biomass since it showed a high direct effect in the same sense of its phenotypic correlations. However, the coefficient of determination obtained by the model applied to full irrigation was higher than that of the water-deficit environment, indicating the importance of variables not included in this study in the determination of alfalfa dry matter biomass under dry conditions.

Abstract Correlations and path analysis allow the understanding of the interrelations between characteristics of interest to the plant breeding. However, in order for their results to be reliable, the undesirable effect of multicollinearity must be excluded. The objective of this study was to estimate the correlations and their partitioning in direct and indirect effects, by path analysis, on the fruit production per plant (FP) of papaya from the heterotic Solo and Formosa groups, using two different strategies to circumvent multicollinearity. Eleven agronomic variables were evaluated in twelve papaya genotypes from the Solo group and nine from the Formosa group. Path analysis was obtained with the FP as the basic variable and to eliminate multicollinearity were used the discard of variables and the ridge path analysis. For the Solo group, fruit length and pulp thickness had greater direct effects on FP. In the Formosa group, the number of commercial fruits had a direct and indirect effect on FP. The two methodologies used to circumvent multicollinearity had high coefficient of determination, with better values for the ridge path analysis. The results indicated that the interrelation between the study characters was different in the Solo and Formosa groups. Thus, indirect selection strategies should be specific for each heterotic group.