Radiopacity Of Glass-ionomer/composite Resin Hybrid Materials.

This study visually compared the radiopacity of seven restorative materials (3 resin-modified glass-ionomer cements, 3 polyacid-modified composite resins, and 1 conventional glass-ionomer cement) to a sound tooth structure sample, and an aluminium stepwedge. All hybrid materials were more radiopaque, except for one resin-modified glass-ionomer cement, than both the tooth structure and conventional glass-ionomer cement.122858

Establishment versus population growth in spatio-temporally varying environments

We consider situations where repeated invasion attempts occur from a source population into a receptor population over extended periods of time. The receptor population contains two locations that provide different expected off- spring numbers to invaders. There is demographic stochasticity in offspring numbers. In addition, temporal variation causes local invader fitnesses to vary. We show that effects of environmental autocorrelation on establishment success depend on spatial covariance of the receptor subpopulations. In situ- ations with a low spatial covariance this effect is positive, whereas high spatial covariance and/or high migration probabilities between the subpopulations causes the effect to be negative. This result reconciles seemingly contradictory results from the literature concerning effects of temporal variation on popu- lation dynamics with demographic stochasticity. We study an example in the context of genetic introgression, where invasions of cultivar plant genes occur through pollen flow from a source population into wild-type receptor populations, but our results have implications in a wider range of contexts, such as the spread of exotic species, metapopulation dynamics and epidemics.Global Challenges (FGGA

Análisis semicuantitativo del calcio y fósforo en el esmalte y la dentina

Existe una serie de características comunes asociadas al proceso biológico de formación de los tejidos calcificados a pesar de que los productos finales sean estructuralmente distintos. La presente investigación tiene como propósito determinar si la ratio Ca/P ratio es la misma para los tejidos calcificados dentales tanto del feto como del adulto y si dicha ratio es diferente al valor de la ratio Ca/P de la hidroxiapatita pura calculada por estequiometría. Se escogió como material de observación el esmalte y la dentina, en muestras de fetos humanos y en un total de 30 ratas adultas de raza Wistar y 20 dientes humanos sanos. Las observaciones se llevaron a cabo por medio de Microscopia Electrónica de Barrido y Microanálisis por separación de energía de rayos X. Los valores totales de la ratio Ca/P para el esmalte oscilaron en un intervalo de 0,9 y 1,2, con una media que se encuentra entre 1,07 y 1,08. Los valores totales de la ratio Ca/P para la dentina oscilan entre 1,03 y 1,12 y la media entre 1,07 y 1,075. No se encontraron diferencias estadísticamente significativas entre esmalte fetal y adulto ni entre la dentina fetal y adulta. Aún no pudiendo definir la existencia de precursores específicos en los tejidos calcificados del diente (esmalte y dentina), nuestros resultados sugieren que no toda la cristalización de estos tejidos corre a cargo de la hidroxiapatita sino que deben haber otros compuestos que expliquen la disminución del valor de la ratio Ca/P en las muestras estudiadas

Análisis semicuantitativo del calcio y fósforo en los tejidos calcificados de la mandíbula

El objetivo de nuestra investigación es realizar un estudio microanalítico semicuantitativo del calcio y el fósforo en los tejidos calcificados de la mandíbula. Dentro de este estudio se pretende calcular el valor de la ratio Ca/P por métodos semicuantitativos y compararlo con los valores estequiométricos de la ratio Ca/P de la hidroxiapatita referidos en la literatura; conocer los valores de la ratio Ca/P obtenidos para el tejido condroide, el hueso lamelar, el hueso fibrorreticular y el cartílago calcificado en las muestras fetales, por una parte, y adultas, por otra; y si existen o no diferencias significativas en la proporción Ca/P obtenidos para feto y adulto. El análisis morfológico de los tejidos calcificados fue realizado por medio de Microrradiografía Electrónica de Barrido (MEB) por electrones retrodispersados (Backscattering), y los resultados permiten afirmar que la ratio obtenida por análisis semicuantitativo mediante dispersión de rayos X de los tejidos calcificados (condroide, hueso lamelar y fibrorreticular) se encuentra más próxima a 1, y que no existen diferencias significativas entre las muestras fetales y de adulto en los tejidos analizados

Updating temperature and salinity mean values and trends in the Western Mediterranean: the RADMED project

Postprin

Factors of Susceptibility of Human Myiasis Caused by the New World Screw-Worm, Cochliomyia hominivorax in São Gonçalo, Rio de Janeiro, Brazil

This study was carried out between July 2007 and June 2008 and reports on the occurrence of human myiasis caused by the New World screwworm, Cochliomyia hominivorax (Coquerel) (Diptera: Calliphoridae) in São Gonçalo in the state of Rio de Janeiro, Brazil. Liquid or solid vaseline was used to suffocate the larvae, which were then preserved in 70% ethanol and sent to the Instituto Oswaldo Cruz for identification. C. hominivorax were identified in all 22 cases of myiasis. There were 12 male and 10 female patients with ages ranging from 03 to 71. Ethnically the highest incidence was among black people, with 17 cases. Open wounds were the main cause of the parasitosis, whereas poor personal hygiene, the low educational level, alcoholism, bedridden patients, and physical or mental disability were possibly secondary factors; in addition to all these factors the income of the patients was very low

Approximations of Shape Metrics and Application to Shape Warping and Empirical Shape Statistics

International audienceThis chapter proposes a framework for dealing with two problems related to the analysis of shapes: the definition of the relevant set of shapes and that of defining a metric on it. Following a recent research monograph by Delfour and Zolésio [8], we consider the characteristic functions of the subsets of ℝ2 and their distance functions. The L 2 norm of the difference of characteristic functions and the L∞ and the W 1,2 norms of the difference of distance functions define interesting topologies, in particular that induced by the well-known Hausdorff distance. Because of practical considerations arising from the fact that we deal with image shapes defined on finite grids of pixels, we restrict our attention to subsets of ℝ2 of positive reach in the sense of Federer [12], with smooth boundaries of bounded curvature. For this particular set of shapes we show that the three previous topologies are equivalent. The next problem we consider is that of warping a shape onto another by infinitesimal gradient descent, minimizing the corresponding distance. Because the distance function involves an inf, it is not differentiable with respect to the shape. We propose a family of smooth approximations of the distance function which are continuous with respect to the Hausdorff topology, and hence with respect to the other two topologies. We compute the corresponding Gâteaux derivatives. They define deformation flows that can be used to warp a shape onto another by solving an initial value problem. We show several examples of this warping and prove properties of our approximations that relate to the existence of local minima. We then use this tool to produce computational de.nitions of the empirical mean and covariance of a set of shape examples. They yield an analog of the notion of principal modes of variation. We illustrate them on a variety of examples

Melhoramento ótico de células solares tandem com base em silício cristalino

CIES2020 - XVII Congresso Ibérico e XIII Congresso Ibero-americano de Energia SolarRESUMO: A estratégia mais promissora para reduzir o custo da eletricidade fotovoltaica é o aumento da eficiência dos sistemas. As células de silício cristalino estão cada vez mais próximas do seu limite teórico de eficiência, sendo por isso progressivamente mais difícil aumentar a sua de eficiência. As células solares tandem com base em silício cristalino são um dos caminhos mais promissores para atingir uma eficiência de conversão para além dos 30% com um custo competitivo. Neste artigo é apresentada uma proposta de célula tandem com base em silício cristalino de com três terminais em que as subcélulas são ligadas em paralelo, sendo também propostas algumas estratégias para melhorar as propriedades óticas deste dispositivo. São apresentados os resultados do desenvolvimento de um método de melhoramento do desempenho ótico do silício cristalino, baseado em gravação química assistida por metal, e de simulações numéricas de dispositivos.ABSTRACT: The most promising strategy to reduce the cost of photovoltaic electricity is to increase the systems’ efficiency. Crystalline silicon cells are getting closer to their theoretical efficiency limit, which is why it is progressively more difficult to increase their efficiency. Crystalline silicon-based tandem solar cells are one of the most promising ways to achieve conversion efficiency beyond 30% at a competitive cost. This article presents a proposal for a tandem cell based on crystalline silicon with three terminals in which the subcells are connected in parallel, and some strategies to improve the optical properties of this device are proposed. The results of the development of a method to improve the optical performance of crystalline silicon, based on metal-assisted chemical etching and numerical device simulations’ results are presented.info:eu-repo/semantics/publishedVersio