Zero-field magnetization reversal of two-body Stoner particles with dipolar interaction

Nanomagnetism has recently attracted explosive attention, in particular, because of the enormous potential applications in information industry, e.g. new harddisk technology, race-track memory[1], and logic devices[2]. Recent technological advances[3] allow for the fabrication of single-domain magnetic nanoparticles (Stoner particles), whose magnetization dynamics have been extensively studied, both experimentally and theoretically, involving magnetic fields[4-9] and/or by spin-polarized currents[10-20]. From an industrial point of view, important issues include lowering the critical switching field $H_c$, and achieving short reversal times. Here we predict a new technological perspective: $H_c$ can be dramatically lowered (including $H_c=0$) by appropriately engineering the dipole-dipole interaction (DDI) in a system of two synchronized Stoner particles. Here, in a modified Stoner-Wohlfarth (SW) limit, both of the above goals can be achieved. The experimental feasibility of realizing our proposal is illustrated on the example of cobalt nanoparticles.Comment: 5 pages, 4 figure

Silent speech: restoring the power of speech to people whose larynx has been removed

Every year, some 17,500 people in Europe and North America lose the power of speech after undergoing a laryngectomy, normally as a treatment for throat cancer. Several research groups have recently demonstrated that it is possible to restore speech to these people by using machine learning to learn the transformation from articulator movement to sound. In our project articulator movement is captured by a technique developed by our collaborators at Hull University called Permanent Magnet Articulography (PMA), which senses the changes of magnetic field caused by movements of small magnets attached to the lips and tongue. This solution, however, requires synchronous PMA-and-audio recordings for learning the transformation and, hence, it cannot be applied to people who have already lost their voice. Here we propose to investigate a variant of this technique in which the PMA data are used to drive an articulatory synthesiser, which generates speech acoustics by simulating the airflow through a computational model of the vocal tract. The project goals, participants, current status, and achievements of the project are discussed below.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Um jogo como estratégia de educação ambiental sobre a biodiversidade da Colômbia

Since the affection for native fauna plays an important role in its conservation and protection, this quasi-experimental study with a pre-/post- design evaluated the effect of an educational game on the identification and affection for the native fauna of Colombia in 291 fourth- to ninth-grade students from 11 rural and urban public schools in Bogotá and Cundinamarca who answered questionnaires before and after 4-5 weeks of ad libitum play during school recess. After contrasting pregame vs. postgame, we found a significant increase in the percentages of successful identification of non-native fauna. When asked to pick their top five favorite animals from an album before and after the game, students chose more non-native than natives animals. As for choosing three animals to be saved, the native and non-native animals before and after the game were the same, two of them native and three non-native. However, the percentage of students who chose three native animals to be saved increased two to five times after the game compared to before the game. Although the result was positive regarding the identification of non-native species, no significant change in the affection for native animals was observed, which emphasizes the challenge and the need to design environmental education tools that generate profound and lasting changes in the affection for native fauna.Debido a que el afecto por la fauna nativa desempeña un papel importante en su conservación y protección, este estudio cuasiexperimental con un diseño pre-/post- evaluó el efecto de un juego educativo sobre la identificación y el afecto por la fauna nativa de Colombia en 291 estudiantes de cuarto a noveno grado de 11 colegios públicos rurales y urbanos de Bogotá y Cundinamarca, quienes respondieron cuestionarios antes y después de 4-5 semanas de juego ad libitum durante el recreo escolar. Al contrastar el prejuego con e  posjuego se encontró un aumento significativo en los porcentajes de identificación acertada de la fauna no nativa. Cuando se pidió a los estudiantes elegir sus cinco animales favoritos de un álbum, prejuego y posjuego eligieron más animales no nativos que nativos. Respecto a la elección de tres animales para ser salvados, los animales nativos y no nativos pre-/pos-juego fueron los mismos, con dos nativos y tres no nativos. No obstante, el porcentaje de alumnos que eligieron tres animales nativos para salvar tuvo un aumento de dos a cinco veces en el posjuego frente al prejuego. Aunque el resultado fue positivo respecto a la identificación de las especies no nativas, no se observó un cambio significativo en el afecto por los animales nativos, lo cual recalca el desafío y la necesidad de diseñar herramientas de educación ambiental que generen cambios profundos y duraderos en el afecto por la fauna nativa.Dado que o aprecio pela fauna nativa desempenha um papel importante em sua conservação e proteção, este estudo quase-experimental com um planejamento pré-/pós- avaliou o efeito do jogo educativo sobre a identificação e o afeto pela fauna nativa da Colômbia em 291 estudantes do quarto ao nono ano de onze colégios estaduais, rurais e urbanos de Bogotá e Cundinamarca, que responderam questionários antes de depois de 4-5 semanas de jogo ad libitum durante o recesso escolar. Ao contrastar o pré-jogo com o pós-jogo evidenciamos um incremento significativo nas porcentagens de identificação acertada da fauna não nativa. Quando solicitamos aos estudantes escolher seus cinco animais favoritos em um álbum, pré--jogo e pós-jogo, eles escolheram mais animais não nativos do que nativos. Em relação com a escolha de três animais para serem protegidos, os animais nativos e não nativos pré/pós-jogo foram os mesmos, com dois nativos e três não nativos. Contudo, a porcentagem de alunos que escolheram três animais nativos para serem protegidos cresceu de duas a cinco vezes no pós-jogo frente ao pré-jogo. Ainda que o resultado foi positivo em relação com a identificação das espécies não nativas, não observamos uma mudança significativa no afeto pelos animais nativos, o que destaca o desafio e a necessidade de criar ferramentas de educação ambiental que possam gerar mudanças profundas e duráveis no aprecio pela fauna nativa

Designing robust rapid transit networks with alternative routes

The aim of this paper is to propose a model for the design of a robust rapid transit network. In this paper, a network is said to be robust when the effect of disruption on total trip coverage is minimized. The proposed model is constrained by three different kinds of flow conditions. These constraints will yield a network that provides several alternative routes for given origin–destination pairs, therefore increasing robustness. The paper includes computational experiments which show how the introduction of robustness influences network design.Unión Europea FP6-021235-2Ministerio de Fomento PT2007-003-08CCPPMinisterio de Educación y Ciencia TRA2005-09068-C03-01 MTM2006-15054Ministerio de Ciencia e Innovación TRA2008-06782-C02-01Natural Sciences and Engineering Research Council of Canada 39682-0

Density-Matrix functional theory of strongly-correlated lattice fermions

A density functional theory (DFT) of lattice fermion models is presented, which uses the single-particle density matrix gamma_{ij} as basic variable. A simple, explicit approximation to the interaction-energy functional W[gamma] of the Hubbard model is derived from exact dimer results, scaling properties of W[gamma] and known limits. Systematic tests on the one-dimensional chain show a remarkable agreement with theBethe-Ansatz exact solution for all interaction regimes and band fillings. New results are obtained for the ground-state energyand charge-excitation gap in two dimensions. A successful description of strong electron correlations within DFT is achieved.Comment: 15 pages, 6 figures Submitted to PR

Avaliação de uma estratégia de educação ambiental sobre o conhecimento da fauna nativa no âmbito da taxonomia folk]

Dado que la taxonomía folk se relaciona con una clasificación innata de los organismos, esta podría ser la base para diseñar, implementar y evaluar estrategias de educación ambiental enfocadas en la biodiversidad y su conservación. El presente estudio evaluó, en el marco de la taxonomía folk, una intervención de educación ambiental basada en el juego para mejorar el conocimiento de las especies nativas de Colombia. 291 estudiantes de 4º - 9º grado de 11 colegios públicos de Cundinamarca jugaron ad libitum durante 4-5 semanas en el tiempo del descanso escolar, sin la presencia de personal de tutoría. Se le pidió al estudiantado que enlistaran todos los animales de Colombia que conocían, pre-juego y post-juego. Los animales nativos mencionados se asignaron a las categorías taxonómicas etnobiológicas “formas de vida”, “genérica” y “específica”. Aunque la composición de las formas de vida no cambió, hubo una disminución en su abundancia (taxones: 2 pre-juego vs. 2 post-juego; menciones: 101 pre-juego vs. 89 post-juego) y un aumento en la composición y abundancia de las categorías genérica (taxones: 82 pre-juego y 104 post-juego; total 115; menciones: 2293 pre-juego vs. 2505 post-juego) y específica (taxones: 24 pre-juego vs. 53 post-juego; total 64; menciones: 400 pre-juego vs. 706 post-juego). Debido a la relación entre la cultura y las categorías taxonómicas etnobiológicas, la disminución en la abundancia de formas de vida, al igual que el aumento en la composición y abundancia de los taxones en las categorías genérica y específica, puede considerarse un resultado ideal para las intervenciones de educación ambiental relacionadas con el conocimiento de la biodiversidad y la identificación de especiesSince folk taxonomy is related to the innate classification of organisms, it could be the basis for designing, implementing, and evaluating environmental education strategies focused on biodiversity and its conservation. Through folk taxonomy, this study assessed a game-based environmental education intervention designed to improve Colombian native species’ knowledge. Two hundred and ninety-one (291) students from 4th to 9th grade of 11 public schools in Cundinamarca, Colombia, played ad libitum during the school recess period without a tutor. Students were asked to list all native Colombian animals they knew before playing for the first time and after having played for four to five weeks. The native animals mentioned were classified into the following ethnobiological taxonomic categories: life forms, generic, and specific. Although the composition of the “life forms” category did not change, there was a decrease in its abundance (taxa: two pre-game vs. two post-game; mentions: 101 pre-game vs. 89 post-game). Besides, there was an increase in composition and abundance in the “generic” category (taxa: 82 pre-game vs. 104 post-game; total 115; mentions: 2293 pre-game vs. 2505 post-game) and in the “specific” category (taxa: 24 pre-game vs. 53 post-game; total 64; mentions: 400 pre-game vs. 706 post-game). Because of the relation the relation between culture and the ethnobiological taxonomic categories, the decrease of abundance of taxa in the “life forms” category, and the increase of composition and abundance of taxa in the “generic” and “specific” categories, the results of this study can be considered as ideal for education interventions based on biodiversity and species identificatio

Maximizing Trip Coverage in the Location of a Single Rapid Transit Alignment

This article describes several heuristics for the construction of a rapid transit alignment. The objective is the maximization of the total origin-destination demand covered by the alignment. Computational results show that the best results are provided by a simple greedy extension heuristic. This conclusion is confirmed on the Sevilla data for scenarios when the upper bound for inter-station distance is greater than 1250 m. Otherwise, when those upper bounds are smaller (750mand 1000 m), an insertion heuristic followed by a post-optimization phase yields the best results. Computational times are always insignificant.Canadian Natural Sciences and Engineering Research Council OGP0039682Ministerio de Ciencia y Tecnología BFM2000-1052-C02-01Ministerio de Ciencia y Tecnología BFM2003-04062/MAT

An Integrated Methodology for the Rapid Transit Network Design

The Rapid Transit System Network Design Problem consists of two intertwined location problems: the determination of alignments and that of the stations. The underlying space, a network or a region of the plane, mainly depends on the place in which the system is being constructed, at grade or elevated, or underground, respectively. For solving the problem some relevant criteria, among them cost and future utilisation, are applied. Urban planners and engineering consulting usually select a small number of corridors to be combined and then analysed. The way of selecting and comparing these alternatives is performed by the application of the four-stage transit planning model. Due to the complexity of the overall problem, during last ten years some efforts have been dedicated to modelling some aspects as optimisation problems and to provide Operations Research methods for solving them. This approach leads to the consideration of a higher number of candidates than that of the classic corridor analysis. The main aim of this paper is to integrate the steps of the transit planning model (trip attraction and generation, trip distribution, mode choice and traffic equilibrium) into an optimisation process.Ministerio de Ciencia y Tecnología BFM2003-04062/MATEMinisterio de Fomento 2003/136

Applications of Direct Injection Soft Chemical Ionisation-Mass Spectrometry for the Detection of Pre-blast Smokeless Powder Organic Additives

Analysis of smokeless powders is of interest from forensics and security perspectives. This article reports the detection of smokeless powder organic additives (in their pre-detonation condition), namely the stabiliser diphenylamine and its derivatives 2-nitrodiphenylamine and 4-nitrodiphenylamine, and the additives (used both as stabilisers and plasticisers) methyl centralite and ethyl centralite, by means of swab sampling followed by thermal desorption and direct injection soft chemical ionisation-mass spectrometry. Investigations on the product ions resulting from the reactions of the reagent ions H3O+ and O2+ with additives as a function of reduced electric field are reported. The method was comprehensively evaluated in terms of linearity, sensitivity and precision. For H3O+, the limits of detection (LoD) are in the range of 41-88 pg of additive, for which the accuracy varied between 1.5 and 3.2%, precision varied between 3.7 and 7.3% and linearity showed R20.9991. For O2+, LoD are in the range of 72 to 1.4 ng, with an accuracy of between 2.8 and 4.9% and a precision between 4.5 and 8.6% and R20.9914. The validated methodology was applied to the analysis of commercial pre-blast gun powders from different manufacturers.(VLID)4826148Accepted versio