Pressure-induced phase transitions in AgClO4

AgClO4 has been studied under compression by x-ray diffraction and density functional theory calculations. Experimental evidence of a structural phase transition from the tetragonal structure of AgClO4 to an orthorhombic barite-type structure has been found at 5.1 GPa. The transition is supported by total-energy calculations. In addition, a second transition to a monoclinic structure is theoretically proposed to take place beyond 17 GPa. The equation of state of the different phases is reported as well as the calculated Raman-active phonons and their pressure evolution. Finally, we provide a description of all the structures of AgClO4 and discuss their relationships. The structures are also compared with those of AgCl in order to explain the structural sequence determined for AgClO4.Comment: 38 pages, 11 figures, 4 table

Quasi-pinning and entanglement in the lithium isoelectronic series

The Pauli exclusion principle gives an upper bound of 1 on the natural occupation numbers. Recently there has been an intriguing amount of theoretical evidence that there is a plethora of additional generalized Pauli restrictions or (in)equalities, of kinematic nature, satisfied by these numbers. Here for the first time a numerical analysis of the nature of such constraints is effected in real atoms. The inequalities are nearly saturated, or quasi-pinned. For rank-six and rank-seven approximations for lithium, the deviation from saturation is smaller than the lowest occupancy number. For a rank-eight approximation we find well-defined families of saturation conditions.Comment: 22 pages, 6 figures, minor changes, references adde

Optimización de secciones ortotropas sometidas a torsión mediante el método de los elementos de contorno

El propósito dellpresente trabajo es la: resolución del problema de optimización de forma de secciones ortótropas, simple y simplemente conexas, sometidas a torsión de Saint-Venant, mediante el método de los elementos de contorno. La función objetivo es el área de la sección, mientras que la única restricción corresponde a una rigidez torsional especificada. Se detalla el algoritmo utilizado para resolver el problema de optimización no lineal resultante, así como los diferentes criterios utilizados para conseguir una redefinición automática de la malla entre dos iteraciones consecutivas. Por último, se incluye una breve descripción del programa desarrollado y varios ejemplos.The aiin of this paper is the solution of the shape optimization problem for simply and multiply-connected orthotropic sections under Saint-Venant torsion by using the Boundary Element Method. The objective function is the area of the section, while the only constraint corresponds to a given torsional stiffness. The nonlinear optimization algorithm is also discussed, so they are the different criteria used to get a consistent and automatic boundary redefinition looking for a ininimum number of iterations in the optimization process. Finaliy, a brief description of the program and severa1 examples are also included.Peer Reviewe

Optimización de secciones ortotropas sometidas a torsión mediante el método de los elementos de contorno

El propósito dellpresente trabajo es la: resolución del problema de optimización de forma de secciones ortótropas, simple y simplemente conexas, sometidas a torsión de Saint-Venant, mediante el método de los elementos de contorno. La función objetivo es el área de la sección, mientras que la única restricción corresponde a una rigidez torsional especificada. Se detalla el algoritmo utilizado para resolver el problema de optimización no lineal resultante, así como los diferentes criterios utilizados para conseguir una redefinición automática de la malla entre dos iteraciones consecutivas. Por último, se incluye una breve descripción del programa desarrollado y varios ejemplos.The aiin of this paper is the solution of the shape optimization problem for simply and multiply-connected orthotropic sections under Saint-Venant torsion by using the Boundary Element Method. The objective function is the area of the section, while the only constraint corresponds to a given torsional stiffness. The nonlinear optimization algorithm is also discussed, so they are the different criteria used to get a consistent and automatic boundary redefinition looking for a ininimum number of iterations in the optimization process. Finaliy, a brief description of the program and severa1 examples are also included.Peer Reviewe

Bipartisanship Breakdown, Functional Networks, and Forensic Analysis in Spanish 2015 and 2016 National Elections

In this paper we present a social network and forensic analysis of the vote counts of Spanish national elections that took place in December 2015 and their sequel in June 2016. Vote counts are extracted at the level of municipalities, yielding an unusually high resolution dataset with over 8000 samples. We initially consider the phenomenon of Bipartisanship breakdown by analysing spatial distributions of several Bipartisanship indices. We find that such breakdown is more prominent close to cosmopolite and largely populated areas and less important in rural areas where Bipartisanship still prevails, and its evolution mildly consolidates in the 2016 round, with some evidence of Bipartisanship reinforcement which we hypothesize to be due to psychological mechanisms of risk aversion. On a third step we explore to which extent vote data are faithful by applying forensic techniques to vote statistics. We first explore the conformance of first digit distributions to Benford's law for each of the main political parties. The results and interpretations are mixed and vary across different levels of aggregation, finding a general good quantitative agreement at the national scale for both municipalities and precincts but finding systematic nonconformance at the level of individual precincts. As a complementary metric, we further explore the co-occurring statistics of voteshare and turnout, finding a mild tendency in the clusters of the conservative party to smear out towards the area of high turnout and voteshare, what has been previously interpreted as a possible sign of incremental fraud. In every case results are qualitatively similar between 2015 and 2016 elections.Comment: 23 pages, 21 figures, accepted for publication in Complexit

Sharing of hand kinematic synergies across subjects in daily living activities

The motor system is hypothesised to use kinematic synergies to simplify hand control. Recent studies suggest that there is a large set of synergies, sparse in degrees of freedom, shared across subjects, so that each subject performs each action with a sparse combination of synergies. Identifying how synergies are shared across subjects can help in prostheses design, in clinical decision-making or in rehabilitation. Subject-specific synergies of healthy subjects performing a wide number of representative daily living activities were obtained through principal component analysis. To make synergies comparable between subjects and tasks, the hand kinematics data were scaled using normative range of motion data. To obtain synergies sparse in degrees of freedom a rotation method that maximizes the sum of the variances of the squared loadings was applied. Resulting synergies were clustered and each cluster was characterized by a core synergy and different indexes (prevalence, relevance for function and within-cluster synergy similarity), substantiating the sparsity of synergies. The first two core synergies represent finger flexion and were present in all subjects. The remaining core synergies represent coordination of the thumb joints, thumb-index joints, palmar arching or fingers adduction, and were employed by subjects in different combinations, thus revealing different subject-specific strategies

Evaluación de las integrales singulares del M.E.C. tridimensional mediante transformaciones no lineales

Se presenta en este trabajo una técnica para la evaluación de las integrales singulares que aparecen en el Método de los Elementos de Contorno en Elasticidad tridimensional, basada en la utilización de transformaciones de coordenadas no lineales, tales como las utilizadas en el caso bidimensional.Peer Reviewe