A Work-Stealing For Dynamic Workload Balancing On CPU-GPU Heterogeneous Computing Platforms

Although many general purpose workloads have been accelerated on graphical processing units (gpus) over the last decade, other applications whose runtime behaviors are dynamic and irregular such as ones based on trees and graphs have suffered from serious workload imbalance problem caused by architectural differences between cpu and gpu processors. In this thesis, we propose a work-stealing framework to overcome such problems. Our proposed framework allows cpu and gpu threads to steal tasks from each other as well as within the same device by leveraging fine-grained data sharing and thread communication feature available on modern cpu-gpu heterogeneous systems. The implementation of bfs application on the top of our framework achieves a minimum of 8.5% performance improvement over the one with coarse-grained task partitioning scheme. It also achieves 16% performance improvement on average over its non-stealing counterpart

Use of remote sensing and GIS in mapping the environmental sensitivity areas for desertification of Egyptian territory

International audienceDesertification is defined in the first art of the convention to combat desertification as "land degradation in arid, semiarid and dry sub-humid areas resulting from climatic variations and human activities". Its consequence include a set of important processes which are active in arid and semi arid environment, where water is the main limiting factor of land use performance in such ecosystem . Desertification indicators or the groups of associated indicators should be focused on a single process. They should be based on available reliable information sources, including remotely sensed images, topographic data (maps or DEM'S), climate, soils and geological data. The current work aims to map the Environmental Sensitivity Areas (ESA's) to desertification in whole territory of Egypt at a scale of 1:1 000 000. ETM satellite images, geologic and soil maps were used as main sources for calculating the index of Environmental Sensitivity Areas (ESAI) for desertification. The algorism is adopted from MEDALLUS methodology as follows; ESAI = (SQI * CQI * VQI)1/3 Where SQI is the soil quality index, CQI is the climate quality index and VQI is the vegetation quality index. The SQI is based on rating the parent material, slope, soil texture, and soil depth. The VQI is computed on bases of rating three categories (i.e. erosion protection, drought resistance and plant cover). The CQI is based on the aridity index, derived from values of annual rainfall and potential evapotranspiration. Arc-GIS 9 software was used for the computation and sensitivity maps production. The results show that the soil of the Nile Valley are characterized by a moderate SQI, however the those in the interference zone are low soil quality indexed. The dense vegetation of the valley has raised its VQI to be good, however coastal areas are average and interference zones are low. The maps of ESA's for desertification show that 86.1% of Egyptian territory is classified as very sensitive areas, while 4.3% as Moderately sensitive, and 9.6% as sensitive. It can be concluded that implementing the maps of sensitivity to desertification is rather useful in the arid and semi arid areas as they give more likely quantitative trend for frequency of sensitive areas. The integration of different factors contributing to desertification sensitivity may lead to plan a successful combating. The usage of space data and GIS proved to be suitable tools to rely estimation and to fulfill the needed large computational requirements. They are also useful in visualizing the sensitivity situation of different desertification parameters

Observation of two distinct pairs fluctuation lifetimes and supercurrents in the pseudogap regime of cuprate junctions

Pairs fluctuation supercurrents and inverse lifetimes in the pseudogap regime are reported. These were measured on epitaxial c-axis junctions of the cuprates, with a PrBa[subscript 2]Cu[subscript 3]O[subscript 7−δ] barrier sandwiched in between two YBa[subscript 2]Cu[subscript 3]O[subscript 7−δ] or doped YBa[subscript 2]Cu[subscript 3]O[subscript y] electrodes, with or without magnetic fields parallel to the a-b planes. All junctions had a T[subscript c](high)≈85–90 K and a T[subscript c](low)≈50–55 K electrodes, allowing us to study pairs fluctuation supercurrents and inverse lifetimes in between these two temperatures. In junctions with a pseudogap electrode under zero field, an excess current due to pair fluctuations was observed which persisted at temperatures above T[subscript c](low), in the pseudogap regime, and up to about T[subscript c](high). No such excess current was observed in junctions without an electrode with a pseudogap. The measured conductance spectra at temperatures above T[subscript c](low) were fitted using a modified fluctuations model by Scalapino [Phys. Rev. Lett. 24, 1052 (1970)] of a junction with a serial resistance. We found that in the pseudogap regime, the conductance vs voltage consists of a narrow peak sitting on top of a very broad peak. This yielded two distinct pairs fluctuation lifetimes in the pseudogap electrode which differ by an order of magnitude up to about T[subscript c](high). Under in-plane fields, these two lifetime values remain separated in two distinct groups, which varied with increasing field moderately. We also found that detection of Amperian pairing [Phys. Rev. X 4, 031017 (2014)] in our cuprate junctions is not feasible, due to Josephson vortices penetration into the superconducting electrodes which drove the necessary field above the depairing field.National Science Foundation (U.S.) (Grant DRM-1522575

Learning to get along despite struggling to get by

A review of evolutionary theories for cooperation, with emphasis on the mechanisms that can favor cooperation and reduce conflict within multicellular organisms, enabling the transition from unicellular to multicellular life

Cavity optomechanics with stoichiometric SiN films

We study high-stress SiN films for reaching the quantum regime with mesoscopic oscillators connected to a room-temperature thermal bath, for which there are stringent requirements on the oscillators' quality factors and frequencies. Our SiN films support mechanical modes with unprecedented products of mechanical quality factor $Q_m$ and frequency $\nu_m$ reaching $Q_{m} \nu_m \simeq2 \times 10^{13}$ Hz. The SiN membranes exhibit a low optical absorption characterized by Im$(n) \lesssim 10^{-5}$ at 935 nm, representing a 15 times reduction for SiN membranes. We have developed an apparatus to simultaneously cool the motion of multiple mechanical modes based on a short, high-finesse Fabry-Perot cavity and present initial cooling results along with future possibilities.Comment: 4 pages, 5 figure