Sharp values for the constants in the polynomial Bohnenblust-Hille inequality

In this paper we prove that the complex polynomial Bohnenblust-Hille constant for $2$-homogeneous polynomials in ${\mathbb C}^2$ is exactly $\sqrt[4]{\frac{3}{2}}$. We also give the exact value of the real polynomial Bohnenblust-Hille constant for $2$-homogeneous polynomials in ${\mathbb R}^2$. Finally, we provide lower estimates for the real polynomial Bohnenblust-Hille constant for polynomials in ${\mathbb R}^2$ of higher degrees.Comment: 16 page

Multi-component symmetry-projected approach for molecular ground state correlations

The symmetry-projected Hartree--Fock ansatz for the electronic structure problem can efficiently account for static correlation in molecules, yet it is often unable to describe dynamic correlation in a balanced manner. Here, we consider a multi-component, systematically-improvable approach, that accounts for all ground state correlations. Our approach is based on linear combinations of symmetry-projected configurations built out of a set of non-orthogonal, variationally optimized determinants. The resulting wavefunction preserves the symmetries of the original Hamiltonian even though it is written as a superposition of deformed (broken-symmetry) determinants. We show how short expansions of this kind can provide a very accurate description of the electronic structure of simple chemical systems such as the nitrogen and the water molecules, along the entire dissociation profile. In addition, we apply this multi-component symmetry-projected approach to provide an accurate interconversion profile among the peroxo and bis($\mu$-oxo) forms of [Cu$_2$O$_2$]$^{2+}$, comparable to other state-of-the-art quantum chemical methods

Excited electronic states from a variational approach based on symmetry-projected Hartree--Fock configurations

Recent work from our research group has demonstrated that symmetry-projected Hartree--Fock (HF) methods provide a compact representation of molecular ground state wavefunctions based on a superposition of non-orthogonal Slater determinants. The symmetry-projected ansatz can account for static correlations in a computationally efficient way. Here we present a variational extension of this methodology applicable to excited states of the same symmetry as the ground state. Benchmark calculations on the C$_2$ dimer with a modest basis set, which allows comparison with full configuration interaction results, indicate that this extension provides a high quality description of the low-lying spectrum for the entire dissociation profile. We apply the same methodology to obtain the full low-lying vertical excitation spectrum of formaldehyde, in good agreement with available theoretical and experimental data, as well as to a challenging model $C_{2v}$ insertion pathway for BeH$_2$. The variational excited state methodology developed in this work has two remarkable traits: it is fully black-box and will be applicable to fairly large systems thanks to its mean-field computational cost

Using FPGA for visuo-motor control with a silicon retina and a humanoid robot

The address-event representation (AER) is a neuromorphic communication protocol for transferring asynchronous events between VLSI chips. The event information is transferred using a high speed digital parallel bus. This paper present an experiment based on AER for visual sensing, processing and finally actuating a robot. The AER output of a silicon retina is processed by an AER filter implemented into a FPGA to produce a mimicking behaviour in a humanoid robot (The RoboSapiens V2). We have implemented the visual filter into the Spartan II FPGA of the USB-AER platform and the Central Pattern Generator (CPG) into the Spartan 3 FPGA of the AER-Robot platform, both developed by authors.Unión Europea IST-2001-34124 (CAVIAR)Ministerio de Ciencia y Tecnología TIC-2003-08164-C03-0

On the evolution of the molecular line profiles induced by the propagation of C-shock waves

We present the first results of the expected variations of the molecular line emission arising from material recently affected by C-shocks (shock precursors). Our parametric model of the structure of C-shocks has been coupled with a radiative transfer code to calculate the molecular excitation and line profiles of shock tracers such as SiO, and of ion and neutral molecules such as H13CO+ and HN13C, as the shock propagates through the unperturbed medium. Our results show that the SiO emission arising from the early stage of the magnetic precursor typically has very narrow line profiles slightly shifted in velocity with respect to the ambient cloud. This narrow emission is generated in the region where the bulk of the ion fluid has already slipped to larger velocities in the precursor as observed toward the young L1448-mm outflow. This strongly suggests that the detection of narrow SiO emission and of an ion enhancement in young shocks, is produced by the magnetic precursor of C-shocks. In addition, our model shows that the different velocity components observed toward this outflow can be explained by the coexistence of different shocks at different evolutionary stages, within the same beam of the single-dish observations.Comment: 7 pages, 4 figures, accepted for publication in Ap

Inestabilidad de laderas en el Valle del Meredal (Asturias, NO de España)

[Resumen] En el valle del Meredal se han identificado 64 movimientos en masa que incluyenmovimientos complejos, deslizamientos rotacionales, flujos y avalanchas rocosas, cuyo desarrollo está condicionado por el diferente comportamiento mecánico de los materiales del sustrato. La aplicación de distintos criterios de cronología relativa basados en el grado de superposición y conservación de las formas ha permitido diferenciar cinco clases de movimientos en masa en cuanto a su edad. Desde el punto de vista regional, la incisión de la red fluvial asociada a los cambios climáticos cuaternarios y a la elevación del margen cantábrico parece ser el factor determinante del origen de esta dinámica.[Abstract] In the Meredal valley 64 landslides, including complex movements, rock slumps,flows and rock avalanches have been identified. The development of these landslides is conditioned by the mechanical behaviour of the different bedrock lithologies. Five chronological classes of movements have been established by applying several relative chronology criteria, as superposition and preservation degree of the landslides. From the regional point of view, fluvial drainage incision linked to quaternary climate changes and to the uplift of the cantabrian margin seems to be determinant in the origin of this dynamics

Incorporación de metodologías participativas al proceso de formación del alumnado universitario

Con el objetivo de mejorar la participación del alumnado en las aulas y la calidad del proceso enseñanza-aprendizaje, se han utilizado técnicas participativas en el desarrollo dela asignatura de Agricultura Ecológica en la Escuela de Ingeniería Técnica Agrícola. Las técnicas empleadas proceden del ámbito del Diagnóstico Rural Participativo, la Educación Social y la Animación Sociocultural. Los resultados nos han permitido concluir que, a pesar de la escasa formación previa de los alumnos en la materia, la adopción de técnicas participativas estimula al alumnado y mejora el proceso de aprendizaje y su interés por la asignatura. Es interesante seguir trabajando en la aplicación de estas metodologías en la docencia universitaria porque facilitan al alumnado la adquisición de un conocimiento holístico en la materia y habilidades para el trabajo en grupo

Synthetic precursor to make alkali activated cements

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