Switching of Magnetic Moments of Nanoparticles by Surface Acoustic Waves

We report evidence of the magnetization reversal in nanoparticles by surface acoustic waves (SAWs). The experimental system consists of isolated magnetite nanoparticles dispersed on a piezoelectric substrate. Magnetic relaxation from a saturated state becomes significantly enhanced in the presence of the SAW at a constant temperature of the substrate. The dependence of the relaxation on SAW power and frequency has been investigated. The effect is explained by the effective ac magnetic field generated by the SAW in the nanoparticles.Comment: Accepted in Europhysics Letter

Imported malaria among African immigrants: is there still a relationship between developed countries and their ex-colonies?

© 2009 Millet et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens

Democratic population decisions result in robust policy-gradient learning: A parametric study with GPU simulations

High performance computing on the Graphics Processing Unit (GPU) is an emerging field driven by the promise of high computational power at a low cost. However, GPU programming is a non-trivial task and moreover architectural limitations raise the question of whether investing effort in this direction may be worthwhile. In this work, we use GPU programming to simulate a two-layer network of Integrate-and-Fire neurons with varying degrees of recurrent connectivity and investigate its ability to learn a simplified navigation task using a policy-gradient learning rule stemming from Reinforcement Learning. The purpose of this paper is twofold. First, we want to support the use of GPUs in the field of Computational Neuroscience. Second, using GPU computing power, we investigate the conditions under which the said architecture and learning rule demonstrate best performance. Our work indicates that networks featuring strong Mexican-Hat-shaped recurrent connections in the top layer, where decision making is governed by the formation of a stable activity bump in the neural population (a "non-democratic" mechanism), achieve mediocre learning results at best. In absence of recurrent connections, where all neurons "vote" independently ("democratic") for a decision via population vector readout, the task is generally learned better and more robustly. Our study would have been extremely difficult on a desktop computer without the use of GPU programming. We present the routines developed for this purpose and show that a speed improvement of 5x up to 42x is provided versus optimised Python code. The higher speed is achieved when we exploit the parallelism of the GPU in the search of learning parameters. This suggests that efficient GPU programming can significantly reduce the time needed for simulating networks of spiking neurons, particularly when multiple parameter configurations are investigated. © 2011 Richmond et al

Determinants of social commitment in the young. Applying the Theory of Reasoned Action

AbstractFramed within the Theory of Reasoned Action, the current work aims to further our knowledge of how social commitment is engendered and what volunteers’ determinants are. Findings to emerge from the empirical study conducted amongst a sample of 488 youngsters aged between 16 and 18 evidence that youngsters’ intention to cooperate with non-government organisations is determined directly by the attitudes they display towards these organisations and towards social issues, and by their immediate environment, and indirectly by their beliefs concerning social conflicts. We highlight the twin role played by attitudes towards non-government organisations (NGOs) throughout the whole process as it proves to be the major determinant of commitment, transforming part of the attitude towards problems into an intention to cooperate, making it a core variable and underscoring the power an organisation's image has to attract volunteers

On the statistical significance of compressed ratios in isobaric labeling: A cross-platform comparison

Isobaric labeling is gaining popularity in proteomics due to its multiplexing capacity. However, copeptide fragmentation introduces a bias that undermines its accuracy. Several strategies have been shown to partially and, in some cases, completely solve this issue. However, it is still not clear how ratio compression affects the ability to identify a protein's change of abundance as statistically significant. Here, by using the "two proteomes" approach (E. coli lysates with fixed 2.5 ratios in the presence or absence of human lysates acting as the background interference) and manipulating isolation width values, we were able to model isobaric data with different levels of accuracy and precision in three types of mass spectrometers: LTQ Orbitrap Velos, Impact, and Q Exactive. We determined the influence of these variables on the statistical significance of the distorted ratios and compared them to the ratios measured without impurities. Our results confirm previous findings1-4 regarding the importance of optimizing acquisition parameters in each instrument in order to minimize interference without compromising precision and identification. We also show that, under these experimental conditions, the inclusion of a second replicate increases statistical sensitivity 2-3-fold and counterbalances to a large extent the issue of ratio compression

On the statistical significance of compressed ratios in isobaric labeling: A cross-platform comparison

Isobaric labeling is gaining popularity in proteomics due to its multiplexing capacity. However, copeptide fragmentation introduces a bias that undermines its accuracy. Several strategies have been shown to partially and, in some cases, completely solve this issue. However, it is still not clear how ratio compression affects the ability to identify a protein's change of abundance as statistically significant. Here, by using the "two proteomes" approach (E. coli lysates with fixed 2.5 ratios in the presence or absence of human lysates acting as the background interference) and manipulating isolation width values, we were able to model isobaric data with different levels of accuracy and precision in three types of mass spectrometers: LTQ Orbitrap Velos, Impact, and Q Exactive. We determined the influence of these variables on the statistical significance of the distorted ratios and compared them to the ratios measured without impurities. Our results confirm previous findings1-4 regarding the importance of optimizing acquisition parameters in each instrument in order to minimize interference without compromising precision and identification. We also show that, under these experimental conditions, the inclusion of a second replicate increases statistical sensitivity 2-3-fold and counterbalances to a large extent the issue of ratio compression

Centros piloto : informe sobre sus características e implantación en Galicia

Se intenta la elaboración de orientaciones técnicas detalladas para la organización pedagógica y la programación de actitudes educativas de dichos centros, a la luz de los principios de la Reforma educativa y de las adquisiciones más recientes de las Ciencias de la Educación, teniendo en cuenta su doble finalidad: investigación educativa y formación del profesorado. 50 centros gallegos de EGB y Bachillerato y centenares de profesionales de la educación así como alumnos. Visitas a los centros y conversaciones con inspectores, directores, profesores y alumnos. Análisis documental y una puesta en común, discusión e intercambio de ideas del equipo investigador. Recoge una serie de recomendaciones generales y otras específicas para cada nivel de enseñanza. Las referentes a la EGB comprenden: enseñanza de la lectura, estudios sociales, enseñanza de la escritura, educación personalizada, globalización, individualización, formación del profesorado, instalaciones escolares, Educación Preescolar, clases de recuperación, salud mental. Los de BUP se ocupan de: currículum, metodología instructiva, formación del profesorado, arquitectura, administración de centros piloto. También se recogen tópicos especiales: la Lengua gallega y la educación, creatividad en la escuela, materiales de instrucción, profesor asesor, evaluación, ocupaciones y servicios especiales de los alumnos en los centros piloto, investigación, aspectos financieros esenciales para el buen desenvolvimiento de los centros piloto. Termina con un informe específico del Centro Piloto Barrie de la Maza. Se señalan a lo largo de cada uno de los apartados.GaliciaBiblioteca de Educación del Ministerio de Educación, Cultura y Deporte; Calle San Agustín, 5 - 3 Planta; 28014 Madrid; Tel. +34917748000; Fax +34917748026; [email protected]