2,752 research outputs found

    Diffusion in infinite and semi-infinite lattices with long-range coupling

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    We prove that for a one-dimensional infinite lattice, with long-range coupling among sites, the diffusion of an initial delta-like pulse in the bulk, is ballistic at all times. We obtain a closed-form expression for the mean square displacement (MSD) as a function of time, and show some cases including finite range coupling, exponentially decreasing coupling and power-law decreasing coupling. For the case of an initial excitation at the edge of the lattice, we find an approximate expression for the MSD that predicts ballistic behavior at long times, in agreement with numerical results.Comment: 4 pages, 5 figures, submitted for publicatio

    Estudio de la influencia de la calidad del agua de riego sobre las propiedades bioquímicas del suelo

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    Trabajo presentado en el VII Simposio Nacional sobre Control de la Degradación y Restauración de Suelos, celebrado en Bilbao, España, del 23 al 26 de junio de 2015Este estudio analiza la influencia de la calidad del agua de riego sobre los parámetros bioquímicos de los Fluvisoles calcáricos representativos en dos zonas del sur de Alicante. Mediante un análisis de componentes principales (ACP) se obtuvo el PC1 (40% variabilidad), referente a la salinidad, siendo útil para diferenciar ambas zonas de estudio, y el PC2 (31%), englobando los parámetros bioquímicos, que distingue las muestras en función de la profundidad. Sin embargo, no se ha observado un efecto negativo sobre las principales actividades enzimáticas en el área más afectada por la salinización.Peer Reviewe

    Industrial districts and migrant enclaves : a model of interaction

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    So far, the relationship between Industrial Districts (IDs; clusters of interconnected local industries) and migrant enclaves (areas with a high concentration of international migrants from a single nationality) has been studied mostly by focusing on the emergence of 'ethnic enclave economies' within the district and/or by highlighting racist conflicts that achieved notoriety in the media. In this study, we contend that there is a more general and complex interaction between the two phenomena. This interaction is mediated by the local context, national regulations, and the organization of the international market, among other factors. By focusing on the case of the ceramic ID of Castelló de la Plana (Spain), we show how this ID with a high rate of job formality, combined with other job opportunities and a unique 'institutional completeness', set up the conditions for a non-conflictive Romanian migrant enclave that reached 14% of the town's total population in 2012. Finally, and also considering another case study of ID and migrant enclave (Prato, and its Chinese enclave), we suggest a model of interaction that should be interpreted taking into account the general dynamics of the international organization of value and the requirements of flexibility and reduction of costs that frame ID

    Complex network modeling of EEG band coupling in dyslexia: An exploratory analysis of auditory processing and diagnosis

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    Complex network analysis has an increasing relevance in the study of neurological disorders, enhancing the knowledge of brain’s structural and functional organization. Network structure and efficiency reveal different brain states along with different ways of processing the information. This work is structured around the exploratory analysis of the brain processes involved in low-level auditory processing. A complex network analysis was performed on the basis of brain coupling obtained from electroencephalography (EEG) data, while different auditory stimuli were presented to the subjects. This coupling is inferred from the Phase-Amplitude coupling (PAC) from different EEG electrodes to explore differences between control and dyslexic subjects. Coupling data allows the construction of a graph, and then, graph theory is used to study the characteristics of the complex networks throughout time for control and dyslexic subjects. This results in a set of metrics including clustering coefficient, path length and small-worldness. From this, different characteristics linked to the temporal evolution of networks and coupling are pointed out for dyslexics. Our study revealed patterns related to Dyslexia as losing the small-world topology. Finally, these graph-based features are used to classify between control and dyslexic subjects by means of a Support Vector Machine (SVM).Spanish Government PGC2018-098813-B-C32Junta de Andalucia UMA20-FEDERJA-086European CommissionNVIDIA CorporationMinistry of Science and Innovation, Spain (MICINN) Spanish GovernmentEuropean CommissionUniversidad de Malaga/CBU

    Financial literacy and risk-taking propensity as predictors of undergraduates' entrepreneurial intention

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    Entrepreneurial intention, as one of the best entrepreneurship predictors, is related to the individual's choice to start a new business. Entrepreneurship education is, without a doubt, the topic that arouses the greatest interest in the entrepreneurship research community. However, empirical evidence is contradictory regarding the influence of entrepreneurship education on entrepreneurial intention, leading academics to the recent claim to delve into the existing heterogeneity regarding the relationship between knowledge, skills and competencies and entrepreneurial intention. Consequently, this article proposes individuals' financial literacy as a relevant predictor of undergraduates' entrepreneurial intention. Financial literacy-entrepreneurship evidence is scarce and limited: (1) they do not focus on entrepreneurial intention; (2) they incompletely measure the multidimensional construct of financial literacy; (3) they do not analyse undergraduates, despite being an important starting point for entrepreneurship. Therefore, this article applies covariance-based structural equation models to 568 Spanish undergraduates with business and tourism degrees to obtain the impact of financial literacy (measured through its three dimensions, i.e., financial knowledge, attitude, and behaviour) on entrepreneurial intention through the mediating role of risk-taking propensity. The results show that: (1) financial knowledge positively influences indirectly; (2) financial attitude negatively influences indirectly; (3) financial behaviour positively influences both directly and indirectly. These findings are highly relevant for the entrepreneurship research community in general and policymakers in particular since we demonstrate the entrepreneurial potential derived from undergraduates' financial literacy thanks to the mediating role of risk-taking propensity, which establishes a novel channel to promote entrepreneurship and, thus, solve the serious youth unemployment problems.Ministerio de Educación y Formación Profesional. Formación de Profesorado Universitario (FPU20/02328). Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

    Sedimentología de una unidad carbonatada lacustre del Mioceno Inferior. Sector nororiental de la Cuenca de Loranca (Provincia de Cuenca, España).

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    En el sector centro-oriental de la Cuenca de Loranca se han identificado tres unidades carbonáticas, entre las localidades de San Pedro de Palmiches y Villaconejos de Trabaque. Estas unidades fueron depositadas durante el Mioceno Inferior y se han denominado: Unidad de Valhondillo, Unidad de Villaconejos y Unidad de Priego-Albalate. En este trabajo se realiza el estudio sedimentológico detallado de la Unidad de Villaconejos, que forma parte del sistema deposicional de Valdeganga. El análisis de los depósitos ha permitido deducir la influencia de la deformación tectónica en el relleno de la cuenca. La Unidad de Villaconejos está constituida por depósitos carbonatados asociados a sedimentos ricos en materia orgánica. El análisis secuencial indica: a) episodios de profundización lacustre. y b) colmataciones lacustres progresivas. Dicha Unidad refleja una evolución sedimentológica. que consiste en un predominio de depósitos lacustres en la base de la sucesión, con un cambio gradual a depósitos más someros, característicos de ambientes palustres

    ORDERING THE MOST RELEVANT SKILLS IN AN ENGINEERING DEGREE USING FUZZY LOGIC. A CASE STUDY

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    Nowadays, the increasing uncertainty of a globalized world economy poses additional challenges to the new agricultural engineering graduates. They have to face increasingly complex challenges, such as increasing demand for agricultural produce in a Climate Change situation, a growing difficulty to guarantee food safety caused by global trade, and an improvement of the resilience of productive systems based on precision agriculture. All of this along with the drawback of a reduced interest of new students in this kind of graduate study. Previous works have dealt with the importance of the general skills in an agricultural engineering degree, showing the relevance of the instrumental skills (capacity for analysis and synthesis, organization and planning capacity, ability to manage information, oral and written communication, foreign language knowledge, computer knowledge, problem resolution, and decision making). This work aims to order these instrumental skills to face the above-mentioned challenges in a more effective way. We are aware that the result of this order presents high doses of uncertainty and ambiguity, and that is why we propose the use of fuzzy logic. The application of this methodology based on fuzzy mathematics can contribute to updating the university degrees so that graduates can successfully the new challenges they will encounter in the workplace. Results show that capacity for analysis and synthesis, organization and planning capacity, and foreign language knowledge is the best-considered skill

    Population study of the native Losine horse

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    The Losine horse, Spanish Losine Pony according to Masón (1969), gets its name for the point of origin, the Losa Valley in the north of the province of Burgos (Spain). This breed maintained its numbers until the 50s when its population declined until reaching a critical point 1986 of only around 180 specimens, in that year, in view of the alarming situation, recovery program for the breed was initiated with the establishment of the first centre for the Breeding and selection of the Losine horse in Pancorbo (Burgos). The fact that so little time has passed since establishing this centre, explains the fact that the Losine horse has a 20.31 p.100 of its population of 154 specimens belonging to the base or founding animals. Further more, it has high average of pedigree founders (16.80) that represent approximately 65 p.100 of the population base. The sequential entrance of founding animal from generation to generation has caused a low ave rage of inbreeding in the Losine horse population ( Fmedia = 1.8 p.100).El caballo Losino, Pony sp. Losino según Masón (1969), recibe su denominación del área original de cría, el Valle de Losa, en el Norte de la provincia de Burgos (España). Esta raza mantuvo sus efectivos hasta los años 50 pero posteriormente su población descendió hasta llegar en 1986 a los límites más críticos de su historia (alrededor de 180 ejemplares). En ese año, en vista de la alarmante situación, se inició un proyecto de recuperación de la raza, creándose en Pancorbo (Burgos) el primer Centro de Cría y Selección del caballo Losino. El hecho de haber transcurrido tan poco espacio de tiempo desde el momento de comenzar, en el Centro de Pancorbo, la recuperación de la Raza del Caballo Losino hace que de los 154 animales que han sido censados hasta el momento del estudio, un 20,31 p.100 sean animales pertenecientes a la población base o fundadora. Así mismo, observamos el elevado número medio de fundadores por pedigrí (16,80) que representa aproximadamente el 65 p.100 de la población base. La entrada secuencial de animales fundadores en cada intervalo generacional, ha motivado que la consanguinidad media de la población de caballos Losinos sea baja ( Fmedia = 1,8 p.100

    Surface solitons in quasiperiodic nonlinear photonic lattices

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    We study discrete surface solitons in semi-infinite, one-dimensional, nonlinear (Kerr), quasiperiodic waveguide arrays of the Fibonacci and Aubry-Andr\'e types, and explore different families of localized surface modes, as a function of optical power content (`nonlinearity') and quasiperiodic strength (`disorder'). We find a strong asymmetry in the power content of the mode as a function of the propagation constant, between the cases of focussing and defocussing nonlinearity, in both models. We also examine the dynamical evolution of a completely-localized initial excitation at the array surface. We find that in general, for a given optical power, a smaller quasiperiodic strength is required to effect localization at the surface than in the bulk. Also, for fixed quasiperiodic strength, a smaller optical power is needed to localize the excitation at the edge than inside the bulk.Comment: 8 pages, 7 figures, submitted for publicatio

    Ac magnetic susceptibility of a molecular magnet submonolayer directly patterned onto a microSQUID sensor

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    We report the controlled integration, via Dip Pen Nanolithography, of monolayer dots of ferritin-based CoO nanoparticles (12 Bohr magnetons) into the most sensitive areas of a microSQUID sensor. The nearly optimum flux coupling between these nanomagnets and the microSQUID improves the achievable sensitivity by a factor 100, enabling us to measure the linear susceptibility of the molecular array down to very low temperatures (13 mK). This method opens the possibility of applying ac susceptibility experiments to characterize two-dimensional arrays of single molecule magnets within a wide range of temperatures and frequencies.Comment: 4 pages 3 figure
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