Clusters en cultivos ilícitos: determinantes y dinámicas

Los datos recientes de areas de cultivos ilícitos indican que a pesar de las fumigaciones, la producción total se ha reducido levemente y los cultivos se han dispersado. Se plantea un modelo teórico que analiza las decisiones tomadas por los cultivadores sobre la localizaci´on de sus parcelas, basando esta escogencia en la dinamización local de los costos esperados. Se utiliza un modelo de agentes para la simulación de la naturaleza compleja de las dinámicas estudiadas. Se encuentra que el incentivo para agruparse aumenta con las economías a escala y se reduce con la expectativa del castigo, sobretodo en zonas con alta densidad de cultivadores.

Counterpoise-corrected geometries and harmonic frequencies of N-body clusters: application to (HF)n (n=3,4)

A study was conducted on the methods of basis set superposition error (BSSE)-free geometry optimization and frequency calculations in clusters larger than a dimer. In particular, three different counterpoise schemes were critically examined. It was shown that the counterpoise-corrected supermolecule energy can be easily obtained in all the cases by using the many-body partitioning of energy

Social perception gaze patterns, symptom severity and resting brain function measured using Arterial Spin Labelling

Autistic spectrum disorder (ASD) is characterised by qualitative alterations in reciprocal social interactions. Some recent studies show alterations in gaze patterns during social perception and rest-functional abnormalities in the ‘social brain network’. This study investigated: i) social perception gaze patterns in children with ASD and controls, ii) the relationship between autism clinical severity and social perception gaze patterns, iii) the relationship between resting cerebral blood flow (rCBF) and social perception gaze patterns. Methods: Nine children with ASD and 9 children with typical development were studied. Eye-tracking was used to detect gaze patterns during presentation of stimuli depicting social scenes. Autism clinical severity was established using the Autism Diagnostic Interview Revised (ADI-R). Arterial spin labelling MRI was used to quantify rCBF. Results: The ASD group looked less at social regions and more at non-social regions than controls. No significant correlation was found between ASD clinical severity and social perception gaze patterns. In the ASD group, gaze behaviour was related to rCBF in the temporal lobe regions at trend level. Positive correlations were found between temporal rCBF and gaze to the face region, while negative correlations were found between temporal rCBF and gaze to non-social regions. Conclusions: These preliminary results suggest that social perception gaze patterns are altered in children with ASD, and could be related to temporal rCBF.

Clusters como modelo para alcanzar la productividad y competitividad industrial en el Ecuador

El desarrollo de una industria no puede ser impulsado desde un sentido únicamente económico, debe contemplar el desarrollo social como un factor fundamental. Un clúster es una opción para involucrar a diferentes sectores de la población en procesos de crecimiento social y económico. El nivel de la calidad de vida de una nación está determinado por la productividad con la cual utiliza su talento humano, recursos naturales y capital, y esto implica planificar procesos institucionales, educacionales y tecnológicos de una manera seria y responsable, considerando el largo plazo y el bienestar de la población. La productividad depende del valor de los productos y servicios en términos de diferenciación, calidad, y de la eficiencia con la que se producen. Si es que todos estos elementos se manejan estratégicamente, lo más lógico es alcanzar la competitividad industrial. Un análisis previo a la propuesta de clusters en el Ecuador es necesario, para definir las mejores condiciones que permitan tener éxito el momento de implementar un proceso productivo como el que se pretende definir con el estudio de los clusters competitivos. Raúl Prebisch precisó tres conceptos para definir el subdesarrollo: la heterogeneidad estructural, la especialización productiva, y, el desarrollo desigual. Desde este punto de vista, la generación de clusters es una alternativa que debe buscar fortalecer un desarrollo más equitativo, involucrando a todos los actores económicos. Esta visión integral del desarrollo va más allá de la complementariedad de las políticas sociales, económicas y ambientales y el ordenamiento democrático, entre capital humano, bienestar social, desarrollo sostenible y ciudadanía: debe interpretarse como el sentido mismo del desarrollo (CEPAL, 2000).

Relationships between lightning and properties of convective cloud clusters

Satellite observations of convective system properties and lightning flash rate are used to investigate the ability of potential lightning parameterizations to capture both the dominant land-ocean contrast in lightning occurrence and regional differences between Africa, the Amazon and the islands of the maritime continent. As found in previous studies, the radar storm height is tightly correlated with the lightning flash rate. A roughly second order power-law fit to the mean radar echo top height above the 0C isotherm is shown to capture both regional and land-ocean contrasts in lightning occurrence and flash rate using a single set of parameters. Recent developments should soon make it possible to implement a parameterization of this kind in global models. Parameterizations based on cloud top height, convective rain rate and convective rain fraction all require the use of separate fits over land and ocean and fail to capture observed differences between continental regions.

New insights on growth mechanisms of protein clusters at surfaces: an AFM and simulation study

Despite its relevance to a wide range of technological and fundamental areas, a quantitative understanding of protein surface clustering dynamics is often lacking. In inorganic crystal growth, surface clustering of adatoms is well described by diffusion-aggregation models. In such models, the statistical properties of the aggregate arrays often reveal the molecular scale aggregation processes. We investigate the potential of these theories to reveal hitherto hidden facets of protein clustering by carrying out concomitant observations of lysozyme adsorption onto mica surfaces, using atomic force microscopy. and Monte Carlo simulations of cluster nucleation and growth. We find that lysozyme clusters diffuse across the substrate at a rate that varies inversely with size. This result suggests which molecular scale mechanisms are responsible for the mobility of the proteins on the substrate. In addition the surface diffusion coefficient of the monomer can also be extracted from the comparison between experiments and simulations. While concentrating on a model system of lysozyme-on-mica, this 'proof of concept' study successfully demonstrates the potential of our approach to understand and influence more biomedically applicable protein-substrate couples.

Strategy clusters and sources of knowledge in French L2 listening comprehension

This article reports on an exploratory investigation into the listening strategies of lower-intermediate learners of French as an L2, including the sources of knowledge they employed in order to comprehend spoken French. Data from 14 learners were analysed to investigate whether employment of strategies in general and sources of knowledge in particular varied according to the underlying linguistic knowledge of the student. While low linguistic knowledge learners were less likely to deploy effectively certain strategies or strategy clusters, high linguistic knowledge levels were not always associated with effective strategy use. Similarly, while there was an association between linguistic knowledge and learners’ ability to draw on more than one source of knowledge in a facilitative manner, there was also evidence that learners tended to over-rely on linguistic knowledge where other sources, such as world knowledge, would have proved facilitative. We conclude by arguing for a fresh approach to listening pedagogy and research, including strategy instruction, bottom-up skill development and a consideration of the role of linguistic knowledge in strategy use.