Transaction Activation scheduling Support for Transactional Memory

Transactional Memory (TM) is considered as one of the most promising paradigms for developing concurrent applications. TM has been shown to scale well on multiple cores when the data access pattern behaves “well,” i.e., when few conflicts are induced. In contrast, data patterns with frequent write sharing, with long transactions, or when many threads contend for a smaller number of cores, produce numerous aborts. These problems are traditionally addressed by application-level contention managers, but they suffer from a lack of precision and provide unpredictable benefits on many workloads. In this paper, we propose a system approach where the scheduler tries to avoid aborts by preventing conflicting transactions from running simultaneously. We use a combination of several techniques to help reduce the odds of conflicts, by (1) avoiding preempting threads running a transaction until the transaction completes, (2) keeping track of conflicts and delaying the restart of a transaction until conflicting transactions have committed, and (3) keeping track of conflicts and only allowing a thread with conflicts to run at low priority. Our approach has been implemented in Linux for Software Transactional Memory (STM) using a shared memory segment to allow fast communication between the STM library and the scheduler. It only requires small and contained modifications to the operating system. Experimental evaluation demonstrates that our approach significantly reduces the number of aborts while improving transaction throughput on various workloads

Optimización del ciclo de minado para la reducción de los costos en la Cantera RB, Ferreñafe.

La investigación surgió de la observación de un problema vinculado deficiencia en el ciclo de minado en la cantera RB, para dicha investigación se buscó trabajar con una muestra es la cantera RB utilizando como tipo y diseño de investigación explicativo. Asimismo, para el recojo de información se utilizaron métodos como el método de observación y técnicas de campo en ella la observación y también la técnica de entrevista, junto a instrumentos empleados como guía de observación de campo, guía de descripción geológica, guía de entrevista a 9 trabajadores de la empresa, además, se utilizó el programa Excel, ArcGIS para realizar los mapas de ubicación, toma y cálculos de los datos. Toda esta metodología le da a este informe de investigación el respaldo, sustento y seriedad respectiva. Finalmente, se obtuvo como resultados que la cantera no cuenta con un control del tonelaje de extracción diario, asimismo no existe relación entre los equipos de carguío y acarreo y hace falta el control de costos en las operaciones de minado, todos estos resultados se presentan por medio de gráficos, cada uno con sus respectivos análisis que contribuyeron a comprobar la hipótesis si se optimiza el ciclo de minado se reducirá los costos en la cantera RB, Ferreñafe, todo este trabajo permitió concluir que implementación de nuevos parámetros de corte directo, carguío y acarreo mejoraron el rendimiento de cada equipo, permitiendo ejercer un control de los costos en todas las operaciones de minado, asimismo el cálculo y eliminación de las demoras en las operaciones de carguío permitieron reducir los costos de operación de S/.126,688.88 a S/. 94,288.88 por mes

Supporting Time-Based QoS Requirements in Software Transactional Memory

International audienceSoftware Transactional Memory (STM) is an optimistic concurrency control mechanism that simplifies parallel programming. Still, there has been little interest in its applicability for reactive applications in which there is a required response time for certain operations. We propose supporting such applications by allowing programmers to associate time with atomic blocks in the forms of deadlines and QoS requirements. Based on statistics of past executions, we adjust the execution mode of transactions by decreasing the level of optimism as the deadline approaches. In the presence of concurrent deadlines, we propose different conflict resolution policies. Execution mode switching mechanisms allow meeting multiple deadlines in a consistent manner, with potential QoS degradations being split fairly among several threads as contention increases, and avoiding starvation. Our implementation consists of extensions to a STM runtime that allow gathering statistics and switching execution modes. We also propose novel contention managers adapted to transactional workloads subject to deadlines. The experimental evaluation shows that our approaches significantly improve the likelihood of a transaction meeting its deadline and QoS requirement, even in cases where progress is hampered by conflicts and other concurrent transactions with deadlines

Escherichia coli TatA and TatB Proteins Have N-out, C-in Topology in Intact Cells

The twin arginine protein transport (Tat) system translocates folded proteins across the cytoplasmic membrane of prokaryotes and the thylakoid membrane of chloroplasts. In Escherichia coli, TatA, TatB, and TatC are essential components of the machinery. A complex of TatB and TatC acts as the substrate receptor, whereas TatA is proposed to form the Tat transport channel. TatA and TatB are related proteins that comprise an N-terminal transmembrane helix and an adjacent amphipathic helix. Previous studies addressing the topological organization of TatA have given conflicting results. In this study, we have addressed the topological arrangement of TatA and TatB in intact cells by labeling of engineered cysteine residues with the membrane-impermeable thiol reagent methoxypolyethylene glycol maleimide. Our results show that TatA and TatB share an N-out, C-in topology, with no evidence that the amphipathic helices of either protein are exposed at the periplasmic side of the membrane. We further show that the N-out, C-in topology of TatA is fixed and is not affected by the absence of other Tat components or by the overproduction of a Tat substrate. These data indicate that topological reorganization of TatA is unlikely to accompany Tat-dependent protein transport

Existence of a novel clathrin-independent endocytic pathway in yeast that depends on Rho1 and formin

Much like mammalian cells, yeast contain a Rho-dependent pathway for endocytosis in addition to canonical clathrin-dependent endocytosis

Experimental determination of the permeability of engineering textiles: Benchmark II

In this second international permeability benchmark, the in-plane permeability values of a carbon fabric were studied by twelve research groups worldwide. One participant also investigated the deformation of the tested carbon fabric. The aim of this work was to obtain comparable results in order to make a step toward standardization of permeability measurements. Unidirectional injections were thus conducted to determine the unsaturated in-plane permeability tensor of the fabric. Procedures used by participants were specified in the guidelines defined for this benchmark. Participants were asked to use the same values for parameters such as fiber volume fraction, injection pressure and fluid viscosity to minimize sources of scatter. The comparison of the results from each participant was encouraging. The scatter between data obtained while respecting the guidelines was below 25%. However, a higher dispersion was observed when some parameters differed from the recommendations of this exercise.The authors are grateful to J.M. Beraud from Hexcel Fabrics for his support that made possible this exercise. The contributions of J.B. Alms, N.C. Correia, S. Advani, E. Ruiz and P.C.T. Goncalves to the preparation of the guidelines document and templates are acknowledged by the participants of this benchmark.Vernet, N.; Ruiz, E.; Advani, S.; Alms, JB.; Aubert, M.; Barburski, M.; Barari, B.... (2014). Experimental determination of the permeability of engineering textiles: Benchmark II. Composites Part A: Applied Science and Manufacturing. 61:172-184. doi:10.1016/j.compositesa.2014.02.010S1721846

Advances in quantum metrology

The statistical error in any estimation can be reduced by repeating the measurement and averaging the results. The central limit theorem implies that the reduction is proportional to the square root of the number of repetitions. Quantum metrology is the use of quantum techniques such as entanglement to yield higher statistical precision than purely classical approaches. In this Review, we analyse some of the most promising recent developments of this research field and point out some of the new experiments. We then look at one of the major new trends of the field: analyses of the effects of noise and experimental imperfections

Análisis, diseño e implementación de un sistema generador de código para la carga óptima, corrección de errores y estandarización de datos para el posterior uso de esta información en el proceso de mediación telefónica de empresas de telecomunicaciones

Este trabajo de Tesis presenta una solución a la interpretación y transformación de datos, aplicable a Linkotel S.A, por medio de la cual sus operadores podrán definir formatos de entrada de datos, así como los procesos que llevarán a cabo la transformación de dichos datos de manera eficiente y confiable. Se da una introducción general y las justificaciones para la realización de este proyecto de tesis. Se analizan los conceptos más importantes de mediación, como son: sus objetivos principales, las etapas que lo conforman y las diversas industrias en las cuales puede ser aplicado este concepto. Se describe en particular la mediación en empresas de telefonía fija y se discute la etapa de transformación de datos de diversos orígenes hacia un formato convergente.GuayaquilIngeniero en Computació