A Conservative Discontinuous Galerkin Scheme With O(N-2) Operations In Computing Boltzmann Collision Weight Matrix

In the present work, we propose a deterministic numerical solver for the homogeneous Boltzmann equation based on Discontinuous Galerkin (DG) methods. The weak form of the collision operator is approximated by a quadratic form in linear algebra setting. We employ the property of >shifting symmetry> in the weight matrix to reduce the computing complexity from theoretical O(N-3) down to O(N-2), with N the total number of freedom for d-dimensional velocity space. In addition, the sparsity is also explored to further reduce the storage complexity. To apply lower order polynomials and resolve loss of conserved quantities, we invoke the conservation routine at every time step to enforce the conservation of desired moments (mass, momentum and/or energy), with only linear complexity. Due to the locality of the DG schemes, the whole computing process is well parallelized using hybrid OpetiMP and MPI. The current work only considers integrable angular cross-sections under elastic and/or inelastic interaction laws. Numerical results on 2-D and 3-D problems are shown.Mathematic

Estudio comparativo de capas de TiO2depositadas por PLD a presión atmosférica y nebulización pirolítica

Las nanocapas cerámicas son ampliamente estudiadas por su interés en aplicaciones tecnológicas. Estos recubrimientos pueden conformar celdas solares, superficies de transmisión, emisión o reflexión selectiva de luz, entre otras tantas aplicaciones. En este trabajo se presenta una comparación entre películas delgadas de TiO2 depositadas por ablación láser pulsado (PLD) y por nebulización pirolítica (sol-gel spray-pyrolisis, SP). La caracterización de las nanocapas se realizó empleando diversas técnicas como microscopía electrónica de barrido (SEM), espectrometría de dispersión de energía de Rayos X (EDS), microscopia de Fuerza Atómica (AFM), Difracción de Rayos X y espectroscopia Raman.TiO 2 layers and nanolayers are widely studied due to its technological applications. This material could be used in solar cells, transmission, emission or selective reflection, among other applications. In this paper, we show a characterization of layers of TiO 2 grown by two different methods, Pulsed Laser Deposition (PLD) at atmospheric pressure and spray pyrolysis (SP). The samples were characterized by SEM, EDS, AFM, XRD and Raman Spectrometry.Fil: Tejerina, Matías Rubén. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Tecnología de Recursos Minerales y Cerámica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Tecnología de Recursos Minerales y Cerámica; ArgentinaFil: Gamba, Martina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Ponce Cabrera, L.. San Petersburg Electrotechnical University; RusiaFil: Alvira, Fernando Carlos. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Linear Theory of Electron-Plasma Waves at Arbitrary Collisionality

The dynamics of electron-plasma waves are described at arbitrary collisionality by considering the full Coulomb collision operator. The description is based on a Hermite-Laguerre decomposition of the velocity dependence of the electron distribution function. The damping rate, frequency, and eigenmode spectrum of electron-plasma waves are found as functions of the collision frequency and wavelength. A comparison is made between the collisionless Landau damping limit, the Lenard-Bernstein and Dougherty collision operators, and the electron-ion collision operator, finding large deviations in the damping rates and eigenmode spectra. A purely damped entropy mode, characteristic of a plasma where pitch-angle scattering effects are dominant with respect to collisionless effects, is shown to emerge numerically, and its dispersion relation is analytically derived. It is shown that such a mode is absent when simplified collision operators are used, and that like-particle collisions strongly influence the damping rate of the entropy mode.Comment: 23 pages, 10 figures, accepted for publication on Journal of Plasma Physic

Octonic Electrodynamics

In this paper we present eight-component values "octons", generating associative noncommutative algebra. It is shown that the electromagnetic field in a vacuum can be described by a generalized octonic equation, which leads both to the wave equations for potentials and fields and to the system of Maxwell's equations. The octonic algebra allows one to perform compact combined calculations simultaneously with scalars, vectors, pseudoscalars and pseudovectors. Examples of such calculations are demonstrated by deriving the relations for energy, momentum and Lorentz invariants of the electromagnetic field. The generalized octonic equation for electromagnetic field in a matter is formulated.Comment: 12 pages, 1 figur

Masculinity and feminity measurement in physical education teachers

Esta investigación tuvo por objetivo analizar las mediciones de masculinidad, feminidad, machismo y sumisión, características asociadas a la personalidad, de un grupo de docentes de Educación Física. Participaron en el estudio 53 docentes de nivel básico que laboran en un programa implementado por una institución gubernamental en la Ciudad de México. El muestreo fue de tipo no probabilístico. Se empleó como instrumento el Inventario de Masculinidad y Feminidad (IMAFE), instrumento confiable y válido en México, sujeto a prueba en otros países, en él se incluyen aspectos de los papeles de género tradicionales: machismo y sumisión. El análisis de los datos se efectúo mediante la prueba “t-Student” y el análisis de varianza de una clasificación, así como la comparación de medias de los resultados arrojados. Se concluye que no hay diferencias estadísticamente significativas en las cuatro escalas propuestas por el IMAFE y las variables de trabajo, sexo, edad y estado civil, en el grupo de docentes de Educación Física, en lo que respecta a las características asociadas a la personalidadThis research aimed to analyze the measurements of masculinity, femininity, machismo and submission features associated with the personality characteristics of a group of physical education teachers. Participated in the study53 basic level teachers working in a program implemented by a government institution in Mexico City. The sampling was not probabilistic type. As a tool for data collection was used the Inventory of Masculinity and femininity (IMAFE), reliable and valid instrument in Mexico, subject to testing in other countries, there aspects of traditional gender roles: machismo and submission. Data analysis undertaken using the “t-student” test and analysis of variance classification and comparison of the results obtained. It is concluded that no statistically significant differences in the four scales proposed by IMAFE and work variables sex, age and marital status in the group of physical education teachers in regard to the characteristics associated with personalit

Isolation and Expansion of Muscle Precursor Cells from Human Skeletal Muscle Biopsies

One of the major issues concerning human skeletal muscle progenitor cells is represented by the efficient isolation and in vitro expansion of cells retaining the ability to proliferate, migrate and differentiate once transplanted. Here we describe a method (1) effective in obtaining human muscle precursor cells both from fresh and frozen biopsies coming from different muscles, (2) selective to yield cells uniformly positive for CD56 and negative for CD34 without FACS sorting, (3) reliable in maintaining proliferative and in vitro differentiative capacity up to passage 10

Percolation, Morphogenesis, and Burgers Dynamics in Blood Vessels Formation

Experiments of in vitro formation of blood vessels show that cells randomly spread on a gel matrix autonomously organize to form a connected vascular network. We propose a simple model which reproduces many features of the biological system. We show that both the model and the real system exhibit a fractal behavior at small scales, due to the process of migration and dynamical aggregation, followed at large scale by a random percolation behavior due to the coalescence of aggregates. The results are in good agreement with the analysis performed on the experimental data.Comment: 4 pages, 11 eps figure

The dissipative linear Boltzmann equation for hard spheres

We prove the existence and uniqueness of an equilibrium state with unit mass to the dissipative linear Boltzmann equation with hard--spheres collision kernel describing inelastic interactions of a gas particles with a fixed background. The equilibrium state is a universal Maxwellian distribution function with the same velocity as field particles and with a non--zero temperature lower than the background one, which depends on the details of the binary collision. Thanks to the H--theorem we then prove strong convergence of the solution to the Boltzmann equation towards the equilibrium.Comment: 17 pages, submitted to Journal of Statistical Physic