3,936 research outputs found
El ritmo de la gramática: la música en la clase de Español como Lengua Extranjera (E/LE)
La motivación es uno de los facores que más influyen en el aprendizaje de una segunda lengua. La música puede actuar como instrumento para estimular a los estudiantes. A través de ella se pueden enseñar (o practicar) una gran variedad de habilidades: la comprensión y expresión oral, la ortografÃa, la escritura creativa, y, por qué no, también la gramática. En este trabajo describimos nuestra experiencia utilizando canciones como medio para reforzar el aprendizaje de ciertos puntos gramaticales, en clases de Español como Lengua Extranjera (E/LE) de nivel elemental e intermedio. Aunque el trabajo tiene un carácter eminentemente práctico, también se hace referencia a algunos temas de tipo teórico, relacionados, en particular, con el desarrollo de la habilidad de comprensión oral
A biophysical perspective on receptor-mediated virus entry with a focus on HIV
As part of their entry and infection strategy, viruses interact with specific receptor molecules expressed on the surface of target cells. The efficiency and kinetics of the virus-receptor interactions required for a virus to productively infect a cell is determined by the biophysical properties of the receptors, which are in turn influenced by the receptors' plasma membrane (PM) environments. Currently, little is known about the biophysical properties of these receptor molecules or their engagement during virus binding and entry. Here we review virus-receptor interactions focusing on the human immunodeficiency virus type 1 (HIV), the etiological agent of acquired immunodeficiency syndrome (AIDS), as a model system. HIV is one of the best characterised enveloped viruses, with the identity, roles and structure of the key molecules required for infection well established. We review current knowledge of receptor-mediated HIV entry, addressing the properties of the HIV cell-surface receptors, the techniques used to measure these properties, and the macromolecular interactions and events required for virus entry. We discuss some of the key biophysical principles underlying receptor-mediated virus entry and attempt to interpret the available data in the context of biophysical mechanisms. We also highlight crucial outstanding questions and consider how new tools might be applied to advance understanding of the biophysical properties of viral receptors and the dynamic events leading to virus entry
Un método integrado de actualización de modelos de elementos finitos utilizando datos procedentes del análisis modal experimental
En este artÃculo se presenta una técnica completa de actualización de modelos de elementos finitos de acuerdo con los resultados obtenidos con el análisis modal experimental, incidiéndose en la integración del proceso y en la necesidad de calidad de los datos de partida.In this article, a complete updating technique for finite element models on the basis of results from experimental modal analysis is presented, with attention focused on the integration of the process and on the necessity for quality in the basic data.Peer Reviewe
Un método integrado de actualización de modelos de elementos finitos utilizando datos procedentes del análisis modal experimental
En este artÃculo se presenta una técnica completa de actualización de modelos de elementos finitos de acuerdo con los resultados obtenidos con el análisis modal experimental, incidiéndose en la integración del proceso y en la necesidad de calidad de los datos de partida.In this article, a complete updating technique for finite element models on the basis of results from experimental modal analysis is presented, with attention focused on the integration of the process and on the necessity for quality in the basic data.Peer Reviewe
Decoherence reduction via continuous dynamical decoupling: Analytical study of the role of the noise spectrum
We analyze the robust character against non-static noise of clock transitions
implemented via a method of continuous dynamical decoupling (CDD) in a
hyperfine Zeeman multiplet in ^{87}\textrm{Rb}. The emergence of features
specific to the quadratic corrections to the linear Zeeman effect is evaluated.
Our analytical approach, which combines methods of stochastic analysis with
time-dependent perturbation theory, allows tracing the decoherence process for
generic noise sources. Working first with a basic CDD scheme, it is shown that
the amplitude and frequency of the (driving) field of control can be
appropriately chosen to force the non-static random input to have a
(time-dependent) perturbative character. Moreover, in the dressed-state
picture, the effect of noise is described in terms of an operative random
variable whose properties, dependent on the driving field, can be analytically
characterized. In this framework, the relevance of the spectral density of the
fluctuations to the performance of the CDD technique is precisely assessed. In
particular, the range of noise correlation times where the method of
decoherence reduction is still efficient is identified. The results obtained in
the basic CDD framework are extrapolated to concatenated schemes. The
generality of our approach allows its applicability beyond the specific atomic
system considered
Effects of leaf wetness duration and temperature on infection of Prunus by Xanthomonas arboricola pv. pruni
Xanthomonas arboricola pv. pruni is the causal agent of bacterial spot disease of stone fruits and almond. The bacterium is distributed throughout the major stone-fruit-producing areas of the World and is considered a quarantine organism in the European Union according to the Council Directive 2000/29/EC, and by the European and Mediterranean Plant Protection Organization. The effect of leaf wetness duration and temperature on infection of Prunus by X. arboricola pv. pruni was determined in controlled environment experiments. Potted plants of the peach-almond hybrid GF-677 were inoculated with bacterial suspensions and exposed to combinations of six leaf wetness durations (from 0 to 24 h) and seven fixed temperatures (from 5 to 35°C) during the infection period. Then, plants were transferred to a biosafety greenhouse, removed from bags, and incubated at optimal conditions for disease development. Although leaf wetness was required for infection of Prunus by X. arboricola pv. pruni, temperature had a greater effect than leaf wetness duration on disease severity. The combined effect of wetness duration and temperature on disease severity was quantified using a modification of the Weibull equation proposed by Duthie. The reduced-form of Duthie's model obtained by nonlinear regression analysis fitted well to data (R = 0.87 and R2adj = 0.85), and all parameters were significantly different from 0. The estimated optimal temperature for infection by X. arboricola pv. pruni was 28.9°C. Wetness periods longer than 10 h at temperatures close to 20°C, or 5 h at temperatures between 25 and 35°C were necessary to cause high disease severity. The predictive capacity of the model was evaluated using an additional set of data obtained from new wetness duration-temperature combinations. In 92% of the events the observed severity agreed with the predicted level of infection risk. The risk chart derived from the reduced form of Duthie's model can be used to estimate the potential risk for infection of Prunus by X. arboricola pv. pruni based on observed or forecasted temperature and wetness durationMinisterio de Educación, Ciencia y Deporte (AGL2013-41405-R, FPU13/04123) of
Spain (https://www.mecd.gob.es/). University of Girona (SING12/13, MPCUdG2016/085) (www.
udg.edu). European Union’s Seventh Framework Programme for research, technological
development and demonstration under grant agreement number 613678 (DROPSA
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