Numerical study of the hard-core Bose-Hubbard Model on an Infinite Square Lattice

We present a study of the hard-core Bose-Hubbard model at zero temperature on an infinite square lattice using the infinite Projected Entangled Pair State algorithm [Jordan et al., Phys. Rev. Lett. 101, 250602 (2008)]. Throughout the whole phase diagram our values for the ground state energy, particle density and condensate fraction accurately reproduce those previously obtained by other methods. We also explore ground state entanglement, compute two-point correlators and conduct a fidelity-based analysis of the phase diagram. Furthermore, for illustrative purposes we simulate the response of the system when a perturbation is suddenly added to the Hamiltonian.Comment: 8 pages, 6 figure

Multi-GPU maximum entropy image synthesis for radio astronomy

The maximum entropy method (MEM) is a well known deconvolution technique in radio-interferometry. This method solves a non-linear optimization problem with an entropy regularization term. Other heuristics such as CLEAN are faster but highly user dependent. Nevertheless, MEM has the following advantages: it is unsupervised, it has a statistical basis, it has a better resolution and better image quality under certain conditions. This work presents a high performance GPU version of non-gridding MEM, which is tested using real and simulated data. We propose a single-GPU and a multi-GPU implementation for single and multi-spectral data, respectively. We also make use of the Peer-to-Peer and Unified Virtual Addressing features of newer GPUs which allows to exploit transparently and efficiently multiple GPUs. Several ALMA data sets are used to demonstrate the effectiveness in imaging and to evaluate GPU performance. The results show that a speedup from 1000 to 5000 times faster than a sequential version can be achieved, depending on data and image size. This allows to reconstruct the HD142527 CO(6-5) short baseline data set in 2.1 minutes, instead of 2.5 days that takes a sequential version on CPU.Comment: 11 pages, 13 figure

Energetics and dynamics of H2_2 adsorbed in a nanoporous material at low temperature

Molecular hydrogen adsorption in a nanoporous metal organic framework structure (MOF-74) was studied via van der Waals density-functional calculations. The primary and secondary binding sites for H$_2$ were confirmed. The low-lying rotational and translational energy levels were calculated, based on the orientation and position dependent potential energy surface at the two binding sites. A consistent picture is obtained between the calculated rotational-translational transitions for different H$_2$ loadings and those measured by inelastic neutron scattering exciting the singlet to triplet (para to ortho) transition in H$_2$. The H$_2$ binding energy after zero point energy correction due to the rotational and translational motions is predicted to be $\sim$100 meV in good agreement with the experimental value of $\sim$90 meV.Comment: 5 pagers, 4 figures. added reference

¿Existe alguna relación entre la capacidad de movimiento funcional y el estado ponderal? Un estudio en escolares españoles

Indexación: Scopus.Background: to examine relations between functional movement patterns and weight status in Spanish primary school children and to determine the differences between sexes. Methods: three hundred and thirty-three, 6-13 years old children (164 boys and 169 girls), participated in this study. The main outcome measures were the body mass index (BMI) and the Functional Movement Screen™ (FMS). Children were classified as normal weight (NW), overweight (OV) or obese (OB) according to international cut-offs. Results: total FMS score was negatively correlated with BMI (p < 0.001). FMS score was different between children from NW, OV and OB groups (p = 0.001), lower with the increased BMI (p < 0.001 between all groups). Significant differences (p < 0.05) between NW, OV and OB were found in deep squat, hurdle step, in-line lunge, shoulder mobility, straight leg-raise and push-up tests. As for the sex differences, girls obtained higher scores (p < 0.05) in in-line lunge, shoulder mobility and straight leg-raise, whereas boys did it in push-up (p = 0.044) test. Conclusions: these results confirm that total FMS score significantly and inversely correlates with BMI in a group of 333 school-age children. As for the sex differences, girls outperform boys in movements requiring flexibility and balance, whilst boys outperform girls in tests where muscular strength is required. © 2018 SENPE and Arán Ediciones S.L.Introducción: examinar la relación entre los patrones de movimiento funcional y el estado ponderal en escolares españoles, determinando también la infl uencia de la variable sexo. Métodos: trescientos treinta y tres niños de 6-13 años de edad (164 niños y 169 niñas), participaron voluntariamente en este estudio. Las variables objeto de estudio fueron el índice de masa corporal (IMC) y la batería de test Functional Movement ScreenTM (FMS). Los niños fueron clasifi cados como normopeso (NW), sobrepeso (OV) y obesos (OB) de acuerdo con los puntos de corte internacionales. Resultados: la puntuación total en el FMS correlacionó de forma negativa y signifi cativa con el IMC (p < 0,001). La puntuación en FMS fue diferente entre las categorías de peso (p = 0,001), hallando un peor rendimiento en FMS conforme aumenta el IMC (p < 0,001 entre todos los grupos). Se hallaron diferencias signifi cativas (p < 0,05) entre NW, OV y OB en los test de deep squat, hurdle step, in-line lunge, shoulder mobility, straight leg-raise and push-up. En cuanto a las diferencias por sexo, las chicas obtuvieron puntuaciones más altas en FMS (p < 0,05) en los test in-line lunge, shoulder mobility and straight leg-raise; mientras los chicos obtuvieron puntuaciones superiores en el test de push-up (p = 0,044). Conclusiones: los resultados confi rman que la puntuación total en el FMS correlaciona signifi cativa y negativamente con el IMC en este grupo de 333 escolares. En cuanto a la infl uencia del sexo, las chicas obtuvieron mayor puntuación que los chicos en los test que requerían fl exibilidad y equilibrio, mientras los chicos fueron superiores en los test en los que predominaba la fuerza muscular.https://www.nutricionhospitalaria.org/index.php/articles/01670/show#

Precompilation: an alternative approach to provide native generic programming support in C++

In C++, Generative Programming (GP) techniques are being used to generate highly customized and optimized products automatically manufactured at compile-time; to provide these functionalities increasing compiling power is required. This work presents an improved compilation model for C++ by adding the ‘precompilation’ phase, leading beyond the Template Meta Programming technique to produce constants and conditional code. Procedural, object-oriented and all the remaining language features become available to produce constants, instances, and compiletime checks, opening, at the same time, a new way for metadata types treatment. In addition to that, when compiling for embedded platforms, some calculi may be moved from resource-critical run time to compile time, taking advantage of the processing power of the host platform. A tool named PRECOMP C++ is also presented in this work as a precompilationenabled C++ extension that supports GP in standard C++ execution during compile time, providing the ability to run metaprograms that operate with more complex data types and features than those supported in Template Meta Programming, such as floating point, pointers arithmetic, inclusion polymorphism, and dynamic memoryII Workshop de Ingeniería de Software y Bases de Datos (WISBD)Red de Universidades con Carreras en Informática (RedUNCI

Multivector Fields and Connections. Setting Lagrangian Equations in Field Theories

The integrability of multivector fields in a differentiable manifold is studied. Then, given a jet bundle $J^1E\to E\to M$, it is shown that integrable multivector fields in $E$ are equivalent to integrable connections in the bundle $E\to M$ (that is, integrable jet fields in $J^1E$). This result is applied to the particular case of multivector fields in the manifold $J^1E$ and connections in the bundle $J^1E\to M$ (that is, jet fields in the repeated jet bundle $J^1J^1E$), in order to characterize integrable multivector fields and connections whose integral manifolds are canonical lifting of sections. These results allow us to set the Lagrangian evolution equations for first-order classical field theories in three equivalent geometrical ways (in a form similar to that in which the Lagrangian dynamical equations of non-autonomous mechanical systems are usually given). Then, using multivector fields; we discuss several aspects of these evolution equations (both for the regular and singular cases); namely: the existence and non-uniqueness of solutions, the integrability problem and Noether's theorem; giving insights into the differences between mechanics and field theories.Comment: New sections on integrability of Multivector Fields and applications to Field Theory (including some examples) are added. The title has been slightly modified. To be published in J. Math. Phy

Structural aspects of Hamilton-Jacobi theory

In our previous papers [11,13] we showed that the Hamilton-Jacobi problem can be regarded as a way to describe a given dynamics on a phase space manifold in terms of a family of dynamics on a lower-dimensional manifold. We also showed how constants of the motion help to solve the Hamilton-Jacobi equation. Here we want to delve into this interpretation by considering the most general case: a dynamical system on a manifold that is described in terms of a family of dynamics (`slicing vector fields') on lower-dimensional manifolds. We identify the relevant geometric structures that lead from this decomposition of the dynamics to the classical Hamilton-Jacobi theory, by considering special cases like fibred manifolds and Hamiltonian dynamics, in the symplectic framework and the Poisson one. We also show how a set of functions on a tangent bundle can determine a second-order dynamics for which they are constants of the motion.Comment: 26 pages. Minor changes (some minor mistakes are corrected