Superconducting gamma-detectors for non-destructive analysis in nuclear safeguards

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, June 2010."June 2010." Cataloged from PDF version of thesis.Includes bibliographical references (p. 41-42).Ultra-high energy resolution superconducting gamma ray detectors operated at temperatures of 0. 1 K can improve the accuracy of non-destructive analysis of nuclear materials. These detectors offer an order of magnitude improvement in resolution over conventional high-purity germanium detectors. The increase in resolution improves the peak-to-background ratio, and reduces errors from line overlap, therefore allowing the identification of weak gamma rays on top of a high Compton background. The higher resolution also improves the accuracy of isotope ratio measurements in fissile material. In order to understand the spectral background and improve the detector sensitivity, GEANT4 Monte Carlo simulations are used to model the low energy response of these superconducting detectors. The models are used to identify the spectral contributions from Compton scattering and from the detector shielding to assess the feasibility of identifying fissile material in spent nuclear fuel. The detector simulations are compared for accuracy to experimental data. We discuss the superconducting detector model, possible improvements in spectrometer configuration, and their use in nuclear safeguards by the IAEA.by Andrea Elizabeth Robles Olson.S.B

Aislamiento e identificación fenotípica y genotípica de cepas de Malassezia spp. en pacientes con Pitiriasis versicolor

68 p.Las especies del género Malassezia forman parte de la microbiota normal de la piel, tanto del ser humano como de animales de sangre caliente. La colonización de estas levaduras parece estar influenciada por factores raciales, sexuales y cambios estacionales, con una frecuencia mayor en épocas cálidas y húmedas, pudiendo causar bajo ciertas condiciones infecciones superficiales a la piel.1 Entre las patologías causadas por estas levaduras se encuentran: pitiriasis versicolor, foliculitis y fungemia, y como factor asociado a dermatitis seborreica, dermatitis atópica, psoriasis, papilomatosis reticulada y confluente de Gougerot-Carteaud, pustulosis cefálica neonatal, onicomicosis y otitis externa maligna.2,3,4 Por mucho tiempo se creía que sólo Malassezia furfur era el agente causante de dichas patologías. Los estudios taxonómicos recientes han permitido identificar nuevas especies de Malassezia, reclasificando los agentes etiológicos y demostrado que existen otras especies de Malassezia involucradas.4 En Chile, existen muy pocos estudios y datos que puedan orientar sobre la epidemiología de las dermatomicosis causadas por las especies pertenecientes al género Malassezia, por lo que es interesante establecer el rol que cumplen estas levaduras, en pacientes pertenecientes a la ciudad de Talca, con pitiriasis versicolor

Biodrying under Greenhouse Conditions as Pretreatment for Horticultural Waste

The biodrying process was studied as an alternative technology to reduce the mass and volume of horticultural waste. Four static piles were prepared inside a greenhouse: two containing whole waste and two consisting of shredded waste. All the piles were compared with a test pile containing whole waste and placed outside the greenhouse. In two cases, ventilation ducts were installed to improve aeration. Each greenhouse was 2.0 m wide, 3.5 m long and 1.16 m high. The air temperature and relative humidity were monitored both inside and outside the greenhouse. Mass, humidity, organic matter and total nitrogen in the waste were measured. Piles inside the greenhouse showed decreases of 80% and 75% in weight and volume, respectively, during the first 16 days. The data obtained in this work suggest that biodrying could improve the handling and transport of horticultural waste while also minimizing the impact of pollutants

A psychological approach in the usage of interests to motivate children to the learning of EFL in a public school of Nuevo León, Mexico.

The present work focuses on 10-year-old children from a public school of Nuevo León, Mexico that have difficulties in the learning of English as a Foreign Language (EFL) and making lesson plans’ adaptations including the students’ interests. The general objective is to examine the relationship between interests and learning of children who show difficulties in the learning process of EFL. The participants in this study are 29 children from a 5th grade primary public school who study English, 2 selected students, one English instructor and one practitioner researcher. The instruments used are based on the concept of triangulation, and the data collection tools are observation forms, interviews, questionnaires about interests and student work. Data analysis from a questionnaire about interests was performed and the main interest categories found were physical activities and videogames. These categories are considered as the thematic content to be used in order to adapt the lesson plans of the EFL classes. The conclusions from the analysis of the students' behaviors and participation during the EFL classes are that the students did not show an improvement during the first class even though it included elements of interest to them, but that changed in the second and third classes. In a scale from 0 to 20 points, it can be observed quantitatively that S1 incremented his participation from 8 in the first class to 15 in the third class, and S2 also incremented his participation from 12 in the first class to 17 in the third class

RENTABILIDAD DEL NOGAL PECANERO BAJO SISTEMAS DE PRODUCCIÓN DE MEDIANA TECNOLOGÃA EN DELICIAS, CHIHUAHUA

Pecans (Carya Illinoinensis [Wangenh] K. Koch) are a native food of North America and represent a high economic crop value in the north of Mexico, mainly in the state of Chihuahua, the biggest pecan nut producer in this country. The goal of this study was to evaluate the profitability of pecan orchards in the municipality of Delicias, Chihuahua. Some microeconomic and market information from 2008 were collected from pecan growers and specialists through the technique of Experts' Panel. Standard financial analysis and a Monte Carlo simulation model were used to evaluate the probabilities of risk for net cash income (NCI) and return on capital employed (RCE). The NCI obtained was $277,000 and RC 111.7%, indicating that pecan orchards show high profitability when is produced under medium-technology conditions in the municipality of Delicias, Chihuahua.Carya Illinoinensis, production costs, Monte Carlo simulation., Agribusiness,

Between atrote enfuror and a X and 0 game

Essay on two urban performances, the processes of interaction and the act of writing.Ensayo sobre dos performances urbanos, los procesos de interacción y el acto de escritura.Ensaio sobre duas performances urbanas, os processos de interação e o ato de escrever