Approximate Models for Neutral Particle Transport in Ducts with Wall Migration

The problem of monoenergetic neutral particle transport in a duct with wall migration for various shielding materials is treated using an approximate one-dimensional model and a Monte Carlo-based multivariate logistic regression model. The one-dimensional model is a third-order approximation in a hierarchy of approximations derived by a weighted residual procedure that accounts for wall migration by means of a kernel density. Physical constants required for the one-dimensional model—scattering probability (c) and the average distance traveled in walls (d) — are calculated using MCNP’s PTRAC and a corresponding parsing code. Numerical results for the one-dimensional model are based on a discrete ordinates solution and compared to MCNP. The logistic regression models are developed using the R language in statistical computing for three explanatory variables— duct radius (r), length (L), and shield thickness plus inner radius (S)— where each parameter is explored via univariate models. Data for the models is collected from MCNP via automated processes using Python and shell scripts. The logistic regression models lead to analytical expressions, which are evaluated by randomly dividing our data set into training and test sets, and calculating predictions

Efecto de Lactobacillus delbrueckii sobre las propiedades texturales de geles binarios de goma gelana

El objetivo del presente trabajo fue evaluar el efecto de la adición de una bacteria probiótica sobre las propiedades texturales de geles comestibles elaborados a base de goma gelana. Para la elaboración de la biopelículas se utilizó un diseño de mezclas simple así: gelana de alto acilo (GAA), gelana de bajo acilo (GBA) y sus mezclas  25GAA/75GBA, 50GAA/50GBA, 75GAA/25GBA, con adición de Lactobacillus delbrueckii. Posteriormente se determinaron las propiedades texturales. Los resultados mostraron que ninguna de las propiedades texturales (dureza, adhesividad, cohesividad, elasticidad) resultan afectadas por la adición de la bacteria probiótica. Sin embargo, todas las formulaciones presentaron características texturales apropiadas para el crecimiento de la bacteria probiótica durante su almacenamiento. Por consiguiente, los geles con adición de bacterias probióticas pueden ser aplicados a una gran variedad de productos alimenticios para incrementar su opción de consumo

CARACTERIZACIÓN DE LOS PRODUCTORES, ADOPCIÓN E IMPACTO ECONÓMICO DEL USO DE LA VARIEDAD DE FRIJOL “PINTO SALTILLO†EN EL NORTE CENTRO DE MÉXICO

In the North-Central Mexico, the main production area of beans in the country, a study was conducted during 2008-2009, whose objectives were to characterize the producers, determine the extent of adoption and to assess the impact of using the bean variety “Pinto Saltilloâ€, generated by INIFAP. The methodological approach was based on a formal interview to a sample of farmers, who were randomly selected from a population of 45,000 registered producers in the pattern of SAGARPA. The sample size was 496 elements. The questionnaire included closed and open questions by analyzing each of the responses through Frequency Analysis. Official sources were consulted for information as well as cooperatives, integrating and marketing of beans. The economic impact analysis of the use of Pinto Saltillo was made considering the increase in performance and / or sale price, and the number of hectares planted. The results indicated that 65.9% of farmers used the variety Pinto Saltillo and that there are different degrees of adoption by state: while in Durango and Chihuahua has been widespread use with rates of 93.3% and 82.8% respectively, Zacatecas recorded use of only 13.3%. The economic benefit generated by this variety released by INIFAP in northern central Mexico with 2008 prices, is approximately 934'000, 000 pesos. The adoption of Pinto Saltillo was a success in production and trade that benefits producers, traders, industrialists and consumers of beans.INIFAP, integrating and marketing organization of beans, bean grown under water scarcity conditions, consumers., Agribusiness,

The Respiratory Exchange Ratio is Associated with Fitness Indicators Both in Trained and Untrained Men: A Possible Application for People with Reduced Exercise Tolerance

Background The respiratory exchange ratio (RER) indirectly shows the muscle's oxidative capacity to get energy. Sedentarism, exercise and physically active lifestyles modify it. For that reason, this study evaluates the associations between RER during sub-maximum exercise and other well established fitness indicators (body fat, maximum heart rate, maximum O 2 uptake, workload, and lactate threshold), in physically active trained and untrained men. Methods The RER, O 2 uptake and blood lactate were measured in eight endurance trained and eight untrained men (age, 22.9 ± 4.5 vs. 21.9 ± 2.8 years; body mass, 67.1 ± 5.4 vs. 72.2 ± 7.7 kg; body fat, 10.6 ± 2.4% vs. 16.6 ± 3.8% and maximum O2 uptake, 68.9 ± 6.3 vs. 51.6 ± 5.8 ml · kg −1 · min −1 ), during maximum exercise test and during three different sub-maximum exercises at fixed workload: below, within or above the lactate threshold. Results Endurance trained men presented higher O 2 uptake, lower blood lactate concentrations and lower RER values than those in untrained men at the three similar relative workloads. Even though with these differences in RER, a strong association (p < 0.05) of RER during sub-maximum exercise with the other well established fitness indicators was observed, and both maximum O 2 uptake and lactate threshold determined more than 57% of its variance (p < 0.05). Conclusions These data demonstrate that RER measurement under sub-maximum exercise conditions was well correlated with other established physical fitness indicators, despite training condition. Furthermore, the results suggest that RER could help obtain an easy approach of fitness status under low exercise intensity and could be utilized in subjects with reduced exercise tolerance

In-Situ Visualization of Long-Range Defect Interactions at the Edge of Melting

Connecting a bulk material's microscopic defects to its macroscopic properties is an age-old problem in materials science. Long-range interactions between dislocations (line defects) are known to play a key role in how materials deform or melt, but we lack the tools to connect these dynamics to the macroscopic properties. We introduce time-resolved dark-field X-ray microscopy to directly visualize how dislocations move and interact over hundreds of micrometers, deep inside bulk aluminum. With real-time movies, we reveal the thermally-activated motion and interactions of dislocations that comprise a boundary, and show how weakened binding forces inhomogeneously destabilize the structure at 99% of the melting temperature. Connecting dynamics of the microstructure to its stability, we provide important opportunities to guide and validate multiscale models that are yet untested

Propagation of charged particle waves in a uniform magnetic field

This paper considers the probability density and current distributions generated by a point-like, isotropic source of monoenergetic charges embedded into a uniform magnetic field environment. Electron sources of this kind have been realized in recent photodetachment microscopy experiments. Unlike the total photocurrent cross section, which is largely understood, the spatial profiles of charge and current emitted by the source display an unexpected hierarchy of complex patterns, even though the distributions, apart from scaling, depend only on a single physical parameter. We examine the electron dynamics both by solving the quantum problem, i. e., finding the energy Green function, and from a semiclassical perspective based on the simple cyclotron orbits followed by the electron. Simulations suggest that the semiclassical method, which involves here interference between an infinite set of paths, faithfully reproduces the features observed in the quantum solution, even in extreme circumstances, and lends itself to an interpretation of some (though not all) of the rich structure exhibited in this simple problem.Comment: 39 pages, 16 figure

Simultaneous Bright- and Dark-Field X-ray Microscopy at X-ray Free Electron Lasers

The structures, strain fields, and defect distributions in solid materials underlie the mechanical and physical properties across numerous applications. Many modern microstructural microscopy tools characterize crystal grains, domains and defects required to map lattice distortions or deformation, but are limited to studies of the (near) surface. Generally speaking, such tools cannot probe the structural dynamics in a way that is representative of bulk behavior. Synchrotron X-ray diffraction based imaging has long mapped the deeply embedded structural elements, and with enhanced resolution, Dark Field X-ray Microscopy (DFXM) can now map those features with the requisite nm-resolution. However, these techniques still suffer from the required integration times due to limitations from the source and optics. This work extends DFXM to X-ray free electron lasers, showing how the $10^{12}$ photons per pulse available at these sources offer structural characterization down to 100 fs resolution (orders of magnitude faster than current synchrotron images). We introduce the XFEL DFXM setup with simultaneous bright field microscopy to probe density changes within the same volume. This work presents a comprehensive guide to the multi-modal ultrafast high-resolution X-ray microscope that we constructed and tested at two XFELs, and shows initial data demonstrating two timing strategies to study associated reversible or irreversible lattice dynamics