Search results for "ample"
showing 10 items of 2398 documents
A method for the preparation of repacked soil cores with homogeneous aggregates for studying microbial nitrogen transformations under highly controll…
1998
International audience; he feasibility of studies on nitrate transformations during incubation in controlled conditions of air-filled porosity using a method of soil core preparation was investigated. Repacked cores were obtained by uniaxial confined compression in a cylindrical mould of a mass of calibrated and conveniently wet aggregates with a water content selected to saturate the textural porosity of the soil aggregates, imposing structural porosity and thereby producing controlled conditions of aeration. The principle and the descrip- tion of the incubation method are explained and some denitrification and respiration data obtained with low and increasing OZ partial pressures are pres…
Sample preparation and analysis of gangliosides and phospholipids from plasma by liquid chromatography coupled to mass spectrometry
2016
Gangliosides (GG) and phospholipids (PL) are two classes of complex and polar lipids exhibiting a wide structural heterogeneity. LC/MS offers an access to this huge diversity but also faces some challenges. Efficient extraction and purification sample methods are thus required to perform accurate and reliable analyses. To this end, GG and PL were extracted from human plasma with three solvent mixtures (CHCl3/MeOH/H2O) of increasing polarity, in comparison with the reference Folch method. GG were further purified with a Phree Phospholipid Removal column, whose sorbent is designed to selectively remove PL. GG and PL classes were then separated under HILIC conditions before analysis using a Qq…
Las Formas Intranquilas. Poética transgenérica y sampleo literario en la escritura de Cristina Rivera Garza
2015
International audience
Electronic noses : specify or disappear
2000
Abstract When the quality control is achieved by using GC or GC/MS, the apparatus must comply with the applicable norms, but what about “electronic noses”? End users demand for formal specifications for selectivity, sensitivity, repeatability and sample throughput. The behavioural modelling of electronic olfactometers may provide specifications for these required parameters. This will allow both the measure itself, and evaluate the influence of the experimental errors on the sample classification. Users may expect to find a methodology allowing the performances of systems to be checked before any final decision and during routine use. We have demonstrated that the system sensitivity and log…
Extrapolation of the Species Accumulation Curve for Incomplete Species Samplings: A New Nonparametric Approach to Estimate the Degree of Sample Compl…
2015
9 pages; International audience; Incomplete species samplings are deemed to remain the common practice in those groups of animals, such as small or micro- invertebrates, with numerous species that often are more or less difficult to detect in the field. Thus, extrapolating the Species Accumulation Curve as far as possible beyond the actual sample size may thus serve as a useful (although imperfect) surrogate to the desired, but practically inaccessible, complete samplings. In this context, several kinds of theoretical or empirical models for the Species Accumulation Curve and also a lot of estimators of the asymptotic limit of the Curve (i.e. total species richness) have been proposed. The …
Hacer Teatro: beneficios para el desarrollo positivo en adolescentes
1970
Este estudio se centra en analizar las opiniones de los adolescentes sobre los beneficios que para ellos supone participar en experiencias teatrales. Se han identificado a partir de seis grupos foco, con una muestra de 53 participantes, de entre 12 y 20 años. Los resultados apuntan a que dichas prácticas: promueven habilidades personales; ofrecen una oportunidad para explorar y expresar sentimientos; proporcionan un contexto de apoyo y seguridad; posibilitan hacer amigos; incrementan habilidades comunicativas; proporcionan recursos para ser empleados en otros ámbitos y momentos de la vida; ayudan a formar la identidad y a mejorar la autoestima; desarrollan destrezas para entender a los otro…
Fact-checking y vigilancia del poder: La verificación del discurso público en los nuevos medios de América Latina
2018
El fact-checking ha experimentado un desarrollo importante en los últimos años, como técnica destinada a la verificación del discurso público, en un momento en que la difusión de noticias falsas o la pérdida de calidad y credibilidad de los medios alcanza cotas preocupantes. Este artículo analiza nueve iniciativas surgidas desde 2010 en media docena de países latinoamericanos, representativas de un ecosistema emergente en una región enfrentada a menudo con problemas para alcanzar una verdadera democracia mediática. Desde una aproximación cualitativa y cuantitativa, esta investigación compara la metodología de trabajo y las modalidades de evaluación que presentan, así como las temáticas y ac…
Comportamiento de las correlaciones producto-momento y tetracórica-policórica en escalas ordinales: un estudio de simulación
2017
El análisis estadístico multivariante de escalas de respuesta tipo Likert, dado su empleo generalizado, resulta un tema controvertido en la comunidad científica, principalmente desde la especificación del problema de la medida. Este trabajo tiene como objeto estudiar cómo afectan diversas condiciones de estas escalas ordinales al cálculo de los coeficientes de correlación producto-momento y tetracórico-policórico. Para ello, se aplica un estudio de simulación en el que se generaron 90 bases de datos con 10 ítems cada una, controlando las siguientes variables: número de categorías de respuesta, distribución simétrica o asimétrica de los datos, tamaño de la muestra y nivel de relación entre l…
A clampless and sutureless aortic anastomosis technique using an endograft connector for aortoiliac occlusive disease in which the aorta cannot be cl…
2012
Bypass surgery in aortoiliac or aortofemoral occlusive disease can be technically demanding and hazardous due to huge calcifications and/or patient co-morbidities. We report about mid-term results of a telescoping sutureless aortic anastomosis technique using endografts as connectors to address such challenging situations. This is a single-center experience (2004–2011) in seven patients (63 ± 6 years) requiring aortoiliac (three) or aortofemoral (four) bypass surgery. In six cases, an aortic stent graft was telescoped into the infrarenal aorta and partly deployed within the aorta and partly outside the aorta. In the first case, a bifurcated stent graft was deployed and the iliac legs were p…
Optimal sample allocation conditioned on a small area model, estimator, and auxiliary data
2018
We have studied optimal sample allocation, associated with small area estimation, when the objective is to obtain as accurate estimates as possible, for the population and for the subpopulations, called as areas here. It is a question of a two-level optimization problem. The basic premise is composed of planned areas, stratified sampling, and small overall sample size predetermined by restricted time and budget resources. Low sample sizes are common in market surveys. During this thesis, we have developed new allocation methods, based on a small area model, estimator, and auxiliary data. The final method, the three-term Pareto allocation, is based on the three terms of the mean-squared erro…