A history of pigs in Africa

2005

A new facility is constructed for measurements of neutron-induced fission cross-sections in the 20-180 MeV energy region versus the np scattering cross-section, which is adopted as the primary neutron standard. The advantage of the experiment compared to earlier studies is that the fission-fragment detection and the neutron-flux measurement via np scattering are performed simultaneously and at the same position in the beam, and, therefore, many sources of systematic errors cancel out. Further reduction of systematic errors is achieved due to "embedded" determination of effective solid angle of particle detectors using α-particles from the radioactive decay of the target nuclei.

These are the lecture notes for CS 15-840B, a hands-on class in programming parallel algorithms. The class was taught in the fall of 1992 by Guy Blelloch, using the programming language NESL. It stressed the clean and concise expression of a variety of parallel algorithms. About 35 graduate students attended the class, of whom 28 took it for credit. These notes were written by students in the class, and were then reviewed and organized by Guy Blelloch and Jonathan Hardwick. The sample NESL code has been converted from the older LISP-style syntax into the new ML-style syntax. These notes are not in a polished form, and probably contain several errors and omissions, particularly with respect to references in the literature. Corrections are welcome.

Review of Research Journal, International Level Multidisciplinary Research Journal, 2017

2. There is a significant difference in the post-test scores of the Educational Technology Achievement Test of both the experimental and control groups. (t ratio = 1.93, p = 0.05)

Behavioural Brain Research, 2014

Aging is associated with impaired learning and memory accompanied by reductions in adult hippocampal neurogenesis and brain expression of neurotrophic factors among other processes. Epigallocatechin-3-gallate (EGCG, a green tea catechin), -alanine (-ala, the precursor of carnosine), and exercise have independently been shown to be neuroprotective and to reduce inflammation and oxidative stress in the central nervous system. We hypothesized that EGCG, ala supplementation or exercise alone would improve learning and memory and increase neurogenesis in aged mice, and the combined intervention would be better than either treatment alone. Male Balb/cByJ mice (19 mo) were given AIN-93M diet with or without EGCG (182 mg/kg/d) and β-ala (417 mg/kg/d). Half of the mice were given access to a running wheel (VWR).

2008

Les études expérimentales sur les instabilités de combustion en régime de prémélange air/combustible pauvre sont généralement menées sur des foyers pour lesquels le nombre de Reynolds visqueux (Re) et le nombre de Reynolds turbulent (Re t ) ont des valeurs nettement plus faibles (Re~2x10 4 , Re t~2 x10 2 ) que celles caractéristiques des foyers aéronautiques (Re~3x10 5 , Re t~3 x10 3 ). Afin de prendre en compte le régime de combustion turbulente dans le couplage thermo-acoustique, il est donc nécessaire d'étudier celui-ci dans une configuration plus réaliste. Le banc d'essais MICAEDI de l'ONERA est un foyer de type marche descendante permettant la production de flammes méthane/air prémélangées et munis d'accès optiques. Les valeurs de turbulence en jeu (Re~10 5 -3×10 5 et Re t~1 0 3 -2×10 3 ) indiquent que la combustion a lieu dans le régime des flammes plissées épaissies du diagramme de Borghi, régime représentatif des foyers réels. Les instabilités de combustion ont été étudiées dans ce foyer par l'intermédiaire de techniques optiques. La position et la structure du front de flamme ont été identifiées par imagerie de fluorescence induite par laser (PLIF) appliquée au radical OH. Les oscillations du champ de vitesse dans le foyer ont été caractérisées par vélocimétrie par image de particules (PIV), et associées aux mouvements de la zone réactive en synchronisant cette technique à la visualisation haute cadence (4000 i/s) de l'émission de chimiluminescence du radical OH* par caméra rapide intensifiée. Les oscillations de pression instationnaire révèlent une fréquence majoritaire autour de 66 Hz, correspondant au mode acoustique longitudinal ¼ d'onde de la veine d'entrée. Les visualisations haute cadence mettent clairement en évidence des remontées instationnaires de la flamme vers l'amont de la marche à la même fréquence, associées à de fortes fluctuations du niveau de la vitesse au-dessus de la marche, celle-ci pouvant parfois s'élever à 3,5 fois la vitesse moyenne ou au contraire s'annuler voire changer de signe, traduisant une inversion momentanée du sens de l'écoulement principal. Par instants la flamme disparaît du champ de la caméra puis réapparaît, observations attribuées à des phénomènes d'extinctions et de réallumages. Les signaux de pression présentent également de très fortes perturbations associées à des modulations en amplitude et fréquence du signal. Ces caractéristiques sont attribuées au fort niveau de turbulence de l'écoulement réactif. Les images PLIF montrent que le front de flamme se compose d'une multitude de petites structures fortement plissées et de poches de mélange méthane/air en combustion qui se détachent de la flamme principale (« combustion par paquets »). La flamme présente un caractère fortement tridimensionnel, et en régime instable se distribue sur toute la hauteur de la veine d'essais. Les résultats obtenus dans cette étude suggèrent la nécessité de modifier les modèles de combustion turbulente dans les simulations LES appliquées aux turbines à gaz industrielles, et en particulier de prendre en compte l'impact des ondes acoustiques sur la structure de flamme.

Journal of Computational Physics, 2014

A new method that solves concurrently the multi-fluid and Maxwell's equations has been developed for plasma simulations. By calculating the stress tensor in the multi-fluid momentum equation by means of computational particles moving in a self-consistent electromagnetic field, the kinetic effects are retained while solving the multi-fluid equations. The Maxwell's and multifluid equations are discretized implicitly in time enabling kinetic simulations over time scales typical of the fluid simulations. The fluid-kinetic Particlein-Cell solver has been implemented in a three-dimensional electromagnetic code, and tested against the ion cyclotron resonance and magnetic reconnection problems. The new method is a promising approach for coupling fluid and kinetic methods in a unified framework.

Rev. Sítio Novo, 2020

Resumen-La investigación aborda el contexto de las instituciones de educación superior brasileña en la década de 90 en comparación con la actualidad, desde una perspectiva política, legislativa, social y estadística. Con énfasis en las directrices del Banco Mundial para los países en desarrollo y las legislaciones brasileñas que guían la educación superior. El compromiso con la educación, el conocimiento y la investigación, en particular, la responsabilidad social universitaria. Los datos estadísticos incluyen un panorama histórico-social de instituciones de educación superior, candidatos, vacantes, ofertas, regiones brasileñas, inscripciones y graduados de la década de 90 y eventos actuales, donde es posible comprender lo que sucede con la educación superior en el país desde la reforma universitaria, hasta el año de 2017 a través del Censo de Educación Superior. El objetivo de la investigación es hacer una comparación entre los datos estadísticos de la década de 90 a la actualidad. Los resultados se presentan en tablas con datos estadísticos de fuentes documentales oficiales y de literaturas. Sin duda, las conclusiones han de lograr hallazgos de poca participación e investimentos del gobierno en la educación superior, una gran expansión del sector privado que contrapone al sector público, ausencias de investigaciones en los grados, discrepancias significativas en las varias regiones del país, entre otros. Palabras clave: Contexto social. Estadística. IES. Político-económico. Ensino universitário brasileiro: uma visão geral da década de 90 para a atualidade. Resumo-A pesquisa aborda o contexto das instituições de ensino superior brasileiras na década de 90 em comparação à atualidade, sob uma perspectiva política, legislativa, social e estatística. Enfatiza-se nas diretrizes do Banco Mundial para os países em desenvolvimento e as leis brasileiras que orientam o ensino superior, o compromisso com a educação, o conhecimento e a pesquisa, em particular a responsabilidade social da universidade. Os dados estatísticos incluem um panorama histórico-social das instituições de ensino superior, candidatos, vagas, ofertas, regiões brasileiras, matrículas e diplomados dos anos de 1990 e aos dados mais atuais, onde é possível compreender o que acontece com o ensino superior no país desde a reforma universitária, até 2017 através do Censo do Ensino Superior. O objetivo da pesquisa é fazer uma comparação estatística entre os dois períodos. Os resultados são apresentados em tabelas com dados estatísticos de fontes documentais oficiais e de literaturas na área. Sem dúvida, as conclusões alcançam resultados de pouca participação e investimentos do governo no ensino superior, uma grande expansão do setor privado que contrasta com o setor público, a ausência de pesquisas nas graduações, discrepâncias significativas nas várias regiões do país, entre outros. Palavras-chave: Contexto social. Estatística. IES. Político-econômico.

Language Rich Europe - Trends in Policies and Practices for Multilingualism in Europe, 2012

The two-dimensional shallow water equations were formulated and numerically 19 solved in an arbitrary curvilinear coordinate system, which offers a relatively high 20 degree of flexibility in representing the natural flow domains with structured meshes. 21 The model employs an efficient TVD-MacCormack scheme, which has second order 22 accuracy in both time and space. Refinements were made to enhance the model's 23 accuracy and stability in computing the shallow wave dynamics in real-world scenarios, 24 with irregular boundaries and uneven beds. In particular, advanced open boundary 25 conditions have been proposed according to the method of characteristics, and rigorous 26 mass conservation has been enforced during the computation at both the inner-domain 27 and the boundaries. These refinements are necessary when modelling the flood 28 inundation over a large area and the tidal oscillation in a macro-tidal estuary. The 29 effectiveness of the refinements was verified by simulating the forced tidal resonance in 30 an idealised condition and the Malpasset dam-break flood. The application of the 31 refined model to the study of tidal oscillations in the Severn Estuary and Bristol 32 Channel can be found in the companion paper. 33 34