Adaptive Partitioning for Large-Scale Dynamic Graphs

Abstract—In the last years, large-scale graph processing has gained increasing attention, with most recent systems placing particular emphasis on latency. One possible technique to improve runtime performance in a distributed graph processing system is to reduce network communication. The most notable way to achieve this goal is to partition the graph by minimizing the num-ber of edges that connect vertices assigned to different machines, while keeping the load balanced. However, real-world graphs are highly dynamic, with vertices and edges being constantly added and removed. Carefully updating the partitioning of the graph to reflect these changes is necessary to avoid the introduction of an extensive number of cut edges, which would gradually worsen computation performance. In this paper we show that performance degradation in dynamic graph processing systems can be avoided by adapting continuously the graph partitions as the graph changes. We present a novel highly scalable adaptive partitioning strategy, and show a number of refinements that make it work under the constraints of a large-scale distributed system. The partitioning strategy is based on iterative vertex migrations, relying only on local information. We have implemented the technique in a graph processing system, and we show through three real-world scenarios how adapting graph partitioning reduces execution time by over 50 % when compared to commonly used hash-partitioning. I

Actividad físico-deportiva extraescolar en alumnos de primaria

En este estudio sociológico se plantea de forma imperiosa detectar las carencias en la actividad física extraescolar de la población escolar. En este sentido, nuestro estudio ahonda un poco más en la actividad físico-deportiva extraescolar en alumnos de Educación Primaria (6-12 años) de un distrito de Madrid (Carabanchel). Los resultados muestran como tan solo un 46,1% de las niñas realiza actividad físico-deportiva extraescolar. Estos porcentajes no son tan preocupantes en el caso de los niños (60,3%). Otro aspecto determinante en este trabajo ha sido el conocer el tiempo de práctica de los escolares que asisten a las actividades, siendo entre una y dos veces por semana el más determinante (92,1%). Teniendo en cuenta las modalidades deportivas y el tiempo de práctica aquí reflejados, padres y educadores debemos promover la práctica regular de ejercicio físico de nuestros niños, fomentando los efectos beneficiosos sobre la salud

A Simple Method to Check the Reliability of Annual Sunspot Number in the Historical Period 1610-1847

A simple method to detect inconsistencies in low annual sunspot numbers based on the relationship between these values and the annual number of active days is described. The analysis allowed for the detection of problems in the annual sunspot number series clustered in a few specific periods and unambiguous, namely: i) before Maunder minimum, ii) the year 1652 during the Maunder minimum, iii) the year 1741 in Solar Cycle -1, and iv) the so-called "lost" solar cycle in 1790s and subsequent onset of the Dalton Minimum.Comment: 15 pages, 3 figures, to be published in Solar Physic

Work and Art: Artistic Contracts of Silverware in the 18 th - 19 th centuries

[Resumo] Con este estudo queremos contribuír a un maior coñecemento de como as relacións xurídico-laborais están presentes desde antigo a través dos contratos artísticos de aprendizaxe na ordenación do traballo e nos contratos das obras na arte da prataría dos ss. XVIII-XIX. De igual maneira buscamos achegarnos á consideración social do traballo dos artistas representado en miniaturas, gravados ou pinturas.[Abstract] With this study we want to contribute to a better understanding of how relations under employment law are present since ancient times through artistic learning contracts in the work organization and in the work contracts in the art of silverware during the 18th-19th centuries. In the same way, we seek to explore the social consideration of the work of artists represented in miniatures, engravings or paintings

The nucleon spin and momentum decomposition using lattice QCD simulations

We determine within lattice QCD, the nucleon spin carried by valence and sea quarks, and gluons. The calculation is performed using an ensemble of gauge configurations with two degenerate light quarks with mass fixed to approximately reproduce the physical pion mass. We find that the total angular momentum carried by the quarks in the nucleon is $J_{u+d+s}{=}0.408(61)_{\rm stat.}(48)_{\rm syst.}$ and the gluon contribution is $J_g {=}0.133(11)_{\rm stat.}(14)_{\rm syst.}$ giving a total of $J_N{=}0.54(6)_{\rm stat.}(5)_{\rm syst.}$ consistent with the spin sum. For the quark intrinsic spin contribution we obtain $\frac{1}{2}\Delta \Sigma_{u+d+s}{=}0.201(17)_{\rm stat.}(5)_{\rm syst.}$. All quantities are given in the $\overline{\textrm{MS}}$ scheme at 2~GeV. The quark and gluon momentum fractions are also computed and add up to $\langle x\rangle_{u+d+s}+\langle x\rangle_g{=}0.804(121)_{\rm stat.}(95)_{\rm syst.}+0.267(12)_{\rm stat.}(10)_{\rm syst.}{=}1.07(12)_{\rm stat.}(10)_{\rm syst.}$ satisfying the momentum sum.Comment: Version published in PR