Experiences in porting mini-applications to OpenACC and OpenMP on heterogeneous systems

This article studies mini-applications—Minisweep, GenASiS, GPP, and FF—that use computational methods commonly encountered in HPC. We have ported these applications to develop OpenACC and OpenMP versions, and evaluated their performance on Titan (Cray XK7 with K20x GPUs), Cori (Cray XC40 with Intel KNL), Summit (IBM AC922 with Volta GPUs), and Cori-GPU (Cray CS-Storm 500NX with Intel Skylake and Volta GPUs). Our goals are for these new ports to be useful to both application and compiler developers, to document and describe the lessons learned and the methodology to create optimized OpenMP and OpenACC versions, and to provide a description of possible migration paths between the two specifications. Cases where specific directives or code patterns result in improved performance for a given architecture are highlighted. We also include discussions of the functionality and maturity of the latest compilers available on the above platforms with respect to OpenACC or OpenMP implementations

Cuerpo y disciplina, orden y poder: Del Instructor Popular a los Tribunales Infantiles

A fines del siglo XIX, en la República Argentina, el periódico mendocino El Instructor Popular publica el intercambio epistolar entre dos graduados de la Escuela Normal de Paraná: Carlos Norberto Vergara y Ernesto A.Bavio. Reprender, reformar y corregir el error, las faltas y la ignorancia, fueron las justificaciones para hacer uso de punteros y palmetas e incorporar la pena, el dolor y la culpa como correctivos, en las instituciones educativas de "la letra con la sangre entra" en manos de "maestros normales que quieren gobernar con el lático". El espistolario visibiliza y reprueba ciertas prácticas que tuvieron al cuerpo infantil como territorio de anclaje para la institucionalización educativa. Puntear esa conjetura nos permite trazar continuidades y discontinuidades entre los "principios de la disciplina" y "los castigos corporales" como antecedentes para los "tribunales infantiles", implementados en la Escuela Quintana de la Provincia de Mendoza, por Florencia Fossatti, en las primeras décadas del siglo XX.Fil: Alvarado, Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Ciencias Humanas, Sociales y Ambientales; Argentin

Fermionic Dark Matter: Physics, Astrophysics, and Cosmology

The nature of dark matter (DM) is one of the most relevant questions in modern astrophysics. We present a brief overview of recent results that inquire into a possible fermionic quantum nature of the DM particles, focusing mainly on the interconnection between the microphysics of the neutral fermions {and the macrophysical structure of galactic halos, including their formation both in the linear and non-linear cosmological regimes. We discuss the general relativistic Ruffini-Arg\"uelles-Rueda (RAR) model of fermionic DM in galaxies, its applications to the Milky Way, the possibility that the Galactic center harbors a DM core instead of a supermassive black hole (SMBH), the S-cluster stellar orbits with an in-depth analysis of the S2's orbit including precession, the application of the RAR model to other galaxy types (dwarf, elliptic, big elliptic and galaxy clusters), and universal galaxy relations. All the above focusing on the model parameters constraints, most relevant to the fermion mass. We also connect the RAR model fermions with particle physics DM candidates, self-interactions, and galactic observables constraints. The formation and stability of core-halo galactic structures predicted by the RAR model and their relation to warm DM cosmologies are also treated. Finally, we briefly discuss how gravitational lensing, dynamical friction, and the formation of SMBHs can also probe the DM nature.Comment: Review paper to be published in Universe, Special Issue "Galactic Center with Gravity

A note about the quantum of area in a non-commutative space

In this note we show that in a two-dimensional non-commutative space the area operator is quantized, this outcome is compared with the result obtained by Loop Quantum Gravity methods.Comment: 6 pages, references added, minor correction

Global instability by runaway collisions in nuclear stellar clusters: Numerical tests of a route for massive black hole formation

The centers of galaxies host nuclear stellar clusters, supermassive black holes, or both, but the origin of this dichotomy is still a mystery. Nuclear stellar clusters are the densest stellar system of the Universe, so they are ideal places for runaway collisions to occur. In these dense clusters it is possible that global instability occurs, triggered by collisions and mergers forming a massive black hole. Here we test a new mechanism to form massive black holes through runaway stellar collisions in nuclear stellar clusters, performing N-body simulations using the code nbody6++gpu. Our idealized models show that there is a critical mass where collisions become very efficient making it possible to form massive black holes in nuclear stellar clusters. The most massive objects reach masses of the order of $10^4-10^5\rm~ M_\odot$. We find that our highest black hole formation efficiency is up to $50\%$ of the stellar mass at the end of the simulation. In real astrophysical systems, the critical mass scale for this transition is expected to occur in stellar clusters of $10^7-10^9\rm~M_\odot$, implying the formation of quite massive central objects.Comment: 11 pages, 6 figure

Supporting clinical information management by NFC technology

Tele-monitorization is a problem with aging people living alone since the vital signs control is complicated for them. In this sense, some initiatives by adapting technologies make easy these controls. In this work we present a solution consist of the Near Field Communications technology adaptability. Mobile phones NFC enabled serving as a middleware between measure devices and people. In addition, a proposal for managing clinical information and medicine prescription are presented.Tele-monitorization is a problem with aging people living alone since the vital signs control is complicated for them. In this sense, some initiatives by adapting technologies make easy these controls. In this work we present a solution consist of the Near Field Communications technology adaptability. Mobile phones NFC enabled serving as a middleware between measure devices and people. In addition, a proposal for managing clinical information and medicine prescription are presented

Delayed development of basal spikelets in wheat explains their increased floret abortion and rudimentary nature

Large differences exist in the number of grains per spikelet across an individual wheat (Triticum aestivum L.) spike. The central spikelets produce the highest number of grains, while apical and basal spikelets are less productive, and the most basal spikelets are commonly only developed in rudimentary form. Basal spikelets are delayed in initiation, yet they continue to develop and produce florets. The precise timing or the cause of their abortion remains largely unknown. Here, we investigated the underlying causes of basal spikelet abortion using shading applications in the field. We found that basal spikelet abortion is likely to be the consequence of complete floret abortion, as both occur concurrently and have the same response to shading treatments. We detected no differences in assimilate availability across the spike. Instead, we show that the reduced developmental age of basal florets pre-anthesis is strongly associated with their increased abortion. Using the developmental age pre-abortion, we were able to predict final grain set per spikelet across the spike, alongside the characteristic gradient in the number of grains from basal to central spikelets. Future efforts to improve spikelet homogeneity across the spike could thus focus on improving basal spikelet establishment and increasing floret development rates pre-abortion

Linear constraints from generally covariant systems with quadratic constraints

How to make compatible both boundary and gauge conditions for generally covariant theories using the gauge symmetry generated by first class constraints is studied. This approach employs finite gauge transformations in contrast with previous works which use infinitesimal ones. Two kinds of variational principles are taken into account; the first one features non-gauge-invariant actions whereas the second includes fully gauge-invariant actions. Furthermore, it is shown that it is possible to rewrite fully gauge-invariant actions featuring first class constraints quadratic in the momenta into first class constraints linear in the momenta (and homogeneous in some cases) due to the full gauge invariance of their actions. This shows that the gauge symmetry present in generally covariant theories having first class constraints quadratic in the momenta is not of a different kind with respect to the one of theories with first class constraints linear in the momenta if fully gauge-invariant actions are taken into account for the former theories. These ideas are implemented for the parametrized relativistic free particle, parametrized harmonic oscillator, and the SL(2,R) model.Comment: Latex file, revtex4, 18 pages, no figures. This version includes the corrections to many misprints of v1 and also the ones of the published version. The conceptual and technical parts of the paper are not altere