Robustness of the magnetoresistance of nanoparticle arrays

Recent work has found that the interplay between spin accumulation and Coulomb blockade in nanoparticle arrays results in peaky I-V and tunneling magnetoresistance (TMR) curves and in huge values of the TMR. We analyze how these effects are influenced by a polarization asymmetry of the electrodes, the dimensionality of the array, the temperature, resistance or charge disorder and long-range interactions. We show that the magnitude and voltage dependence of the TMR does not change with the dimensionality of the array or the presence of junction resistance disorder. A different polarization in the electrodes modifies the peak shape in the I-V and TMR curves but not their order of magnitude. Increasing the temperature or length of the interaction reduces to some extent the size of the peaks, being the reduction due to long-range interactions smaller in longer arrays. Charge disorder should be avoided to observe large TMR values.Comment: 8 pages, 8 figure

Miura Transformation between two Non-Linear Equations in 2+1 dimensions

A Dispersive Wave Equation in 2+1 dimensions (2LDW) widely discussed by different authors is shown to be nothing but the modified version of the Generalized Dispersive Wave Equation (GLDW). Using Singularity Analysis and techniques based upon the Painleve Property leading to the Double Singular Manifold Expansion we shall find the Miura Transformation which converts the 2LDW Equation into the GLDW Equation. Through this Miura Transformation we shall also present the Lax pair of the 2LDW Equation as well as some interesting reductions to several already known integrable systems in 1+1 dimensions.Comment: 14 pages, latex. Journal of Mathematical Physics (to appear

1+1 spectral problems arising from the Manakov-Santini system

This paper deals with the spectral problem of the Manakov Santini system. The point Lie symmetries of the Lax pair have been identified. Several similarity reductions arise from these symmetries. An important benefit of our procedure is that the study of the Lax pair instead of the partial differential equations yields the reductions of the eigenfunctions and also the spectral parameter. Therefore, we have obtained five interesting spectral problems in 1+1 dimensions

Policy Monitoring on Accessible Technology for Inclusive Education – Research Findings and Requirements for a Software Tool

Statistics about disabled people usually do not receive as much attention as statistics highlighting other socio-economic problems. However, such statistics is important due to its actual weight. According to the World Health Organization (WHO), about 15% of the world population, meaning one billion people, live with disabilities, and 80% of them live in developing countries. UNESCO claims that 90% of the children with disabilities in developing countries do not attend schools. Thus, it is of upmost relevance to raise awareness and strengthen public policies for the use of Assistive Technology (AT) to ensure Inclusive Education and Access to Information for people with disabilities, particularly in developing countries. Contributing to such efforts, this paper presents research findings on policy monitoring and evaluation tools and defines requirements for a software tool for monitoring a public policy for the use of AT to ensure Inclusive Education and Access to Information for persons with visual and hearing impairments, with particular focus on Uganda. The research findings and tool requirements presented in this paper could be adapted by other countries that pursue such policies.Facultad de Informátic

Alineación arqueoastronómica en A Ferradura (Amoeiro-Ourense)

Presentamos un fenómeno arqueoastronómico centrado en el solsticio de invierno, novedoso en el contexto arqueológico del Noroeste peninsular. Está atestiguado mediante un petroglifo situado en el interior de un abrigo rocoso natural en un contexto arqueológico que provisionalmente consideramos como un santuario de la Segunda edad del Hierro. El estudio mediante el método comparativo de los dos petroglifos más destacados del santuario nos lleva a proponer que estamos ante la expresión material minimalista de una ideología religiosa que se expresa, con otras formas materiales, en el Estanque Monumental de Bibracte o el Capitolio de Roma. Esta ideología gira en torno a las nociones de tiempo y espacio y relaciona el orden jerárquico de la sociedad con el ritmo de la vida natural presidida por el sol

Assessment of the Sustainability of Extensive Livestock Farms on the Common Grasslands of the Natural Park Sierra de Grazalema

The communal pastures of the Natural Park Sierra de Grazalema are grazed by a total of 23 extensive herds, of which 75% are certified as organic, although only 39% are subsidized for being organic. In a previous research work, these farms were characterized and classified into four typologies: group 1 (farms of intermediate size and without sheep), group 2 (large and very extensive farms), group 3 (farms with sheep suitable for both meat and milk) and group 4 (farms with dairy goat milk and without cattle). In this article, the sustainability of these farms is evaluated and compared based on their organic orientation (whether they are organic or conventional) and their typology (the four typologies indicated), as a tool for decision-making in the management of this natural protected area. To do so, 49 sustainability indexes have been generated, grouped into five attributes: adaptability, self-management, equity, stability, and productivity. The results indicate that, at the global level, there are no significant differences in sustainability between the organic and conventional farms studied. In contrast, depending on the typologies, the results indicate that group 3 is the most sustainable, followed by groups 1 and 4, with group 2 being the one with the lowest level of sustainability. Taking into account that there are a reduced number of herds grazing in this natural park, it is essential to solve the weaknesses of these farms in order to guarantee that they continue to maintain environmental equilibrium in the grasslands

Spike-based VITE control with Dynamic Vision Sensor applied to an Arm Robot.

Spike-based motor control is very important in the field of robotics and also for the neuromorphic engineering community to bridge the gap between sensing / processing devices and motor control without losing the spike philosophy that enhances speed response and reduces power consumption. This paper shows an accurate neuro-inspired spike-based system composed of a DVS retina, a visual processing system that detects and tracks objects, and a SVITE motor control, where everything follows the spike-based philosophy. The control system is a spike version of the neuroinspired open loop VITE control algorithm implemented in a couple of FPGA boards: the first one runs the algorithm and the second one drives the motors with spikes. The robotic platform is a low cost arm with four degrees of freedom.Ministerio de Ciencia e Innovación TEC2009-10639-C04-02/01Ministerio de Economía y Competitividad TEC2012-37868-C04-02/0

The lightest flavor--singlet qqq baryons as witnesses to color

We present a new computation in a field-theoretical model of Coulomb gauge QCD of the first radial and angular excitations of a qqq system in a SU(3) flavor singlet state, Lambda_S. The traditional motivation for the study is that the absence of flavor singlets in the lowest-lying spectrum is a direct consequence of the color degree of freedom. (The calculation is tested with decuplet baryons Delta(1232) and Omega(1672).) We also analyze decay branching fractions of the flavor singlet baryon for various masses with the simplest effective Lagrangians