Task mapping on a dragonfly supercomputer

The dragonfly network topology has recently gained traction in the design of high performance computing (HPC) systems and has been implemented in large-scale supercomputers. The impact of task mapping, i.e., placement of MPI ranks onto compute cores, on the communication performance of applications on dragonfly networks has not been comprehensively investigated on real large-scale systems. This paper demonstrates that task mapping affects the communication overhead significantly in dragonflies and the magnitude of this effect is sensitive to the application, job size, and the OpenMP settings. Among the three task mapping algorithms we study (in-order, random, and recursive coordinate bisection), selecting a suitable task mapper reduces application communication time by up to 47%

Signs of low frequency dispersions in disordered binary dielectric mixtures (50-50)

Dielectric relaxation in disordered dielectric mixtures are presented by emphasizing the interfacial polarization. The obtained results coincide with and cause confusion with those of the low frequency dispersion behavior. The considered systems are composed of two phases on two-dimensional square and triangular topological networks. We use the finite element method to calculate the effective dielectric permittivities of randomly generated structures. The dielectric relaxation phenomena together with the dielectric permittivity values at constant frequencies are investigated, and significant differences of the square and triangular topologies are observed. The frequency dependent properties of some of the generated structures are examined. We conclude that the topological disorder may lead to the normal or anomalous low frequency dispersion if the electrical properties of the phases are chosen properly, such that for ``slightly'' {\em reciprocal mixture}--when $\sigma_1\gg\sigma_2$, and $\epsilon_1<\epsilon_2$--normal, and while for ``extreme'' {\em reciprocal mixture}--when $\sigma_1\gg\sigma_2$, and $\epsilon_1\ll\epsilon_2$--anomalous low frequency dispersions are obtained. Finally, comparison with experimental data indicates that one can obtain valuable information from simulations when the material properties of the constituents are not available and of importance.Comment: 13 pages, 7 figure

On micro-structural effects in dielectric mixtures

The paper presents numerical simulations performed on dielectric properties of two-dimensional binary composites on eleven regular space filling tessellations. First, significant contributions of different parameters, which play an important role in the electrical properties of the composite, are introduced both for designing and analyzing material mixtures. Later, influence of structural differences and intrinsic electrical properties of constituents on the composite's over all electrical properties are investigated. The structural differences are resolved by the spectral density representation approach. The numerical technique, without any {\em a-priori} assumptions, for extracting the spectral density function is also presented.Comment: 24 pages, 8 figure and 7 tables. It is submitted to IEEE Transactions on Dielectrics and Electrical Insulatio

Extracting spectral density function of a binary composite without a-priori assumption

The spectral representation separates the contributions of geometrical arrangement (topology) and intrinsic constituent properties in a composite. The aim of paper is to present a numerical algorithm based on the Monte Carlo integration and contrainted-least-squares methods to resolve the spectral density function for a given system. The numerical method is verified by comparing the results with those of Maxwell-Garnett effective permittivity expression. Later, it is applied to a well-studied rock-and-brine system to instruct its utility. The presented method yields significant microstructural information in improving our understanding how microstructure influences the macroscopic behaviour of composites without any intricate mathematics.Comment: 4 pages, 5 figures and 1 tabl

Fractional Equations of Curie-von Schweidler and Gauss Laws

The dielectric susceptibility of most materials follows a fractional power-law frequency dependence that is called the "universal" response. We prove that in the time domain this dependence gives differential equations with derivatives and integrals of noninteger order. We obtain equations that describe "universal" Curie-von Schweidler and Gauss laws for such dielectric materials. These laws are presented by fractional differential equations such that the electromagnetic fields in the materials demonstrate "universal" fractional damping. The suggested fractional equations are common (universal) to a wide class of materials, regardless of the type of physical structure, chemical composition or of the nature of the polarization.Comment: 11 pages, LaTe

Neuroprotective effect of magnesium on lipid peroxidation and axonal function after experimental spinal cord injury

Study design: An experimental study examining the neuroprotective effect of magnesium on axonal function and lipid peroxidation in a rat model of acute traumatic spinal cord injury. Objective: To determine the effectiveness of postinjury treatment with magnesium on evoked potentials and lipid peroxidation after spinal cord injury (SCI). Setting: Pamukkale University, Denizli, Turkey. Methods: Spinal cord injury occurred in 30 rats with an aneurysm clip at T9 and the rats were randomly assigned to undergo subcutaneous administration of one of the following at 1 h after injury: (1) Physiological saline (n = 10); (2) MgSO4, 300 mg/kg (n = 10) and (3) MgSO4, 600 mg/kg (n = 10). Spinal somatosensory evoked potentials (SSEPs) were recorded before injury, 30 min after injury and 3 h after injections. Rats were killed 24 h after the injury, and malondialdehyde (MDA) levels were measured. Results: Following SCI, there were significant decreases in the amplitudes of P1 and N1 (P 0.001) and only high-dose magnesium improved the SSEPs (P &lt; 0.01). On the other hand, there was significant difference in lipid peroxide content between high-dose magnesium treated group and both of saline treated and low-dose magnesium treated groups (P &lt; 0.01). Conclusion: These results suggest that magnesium has a dose-dependent neuroprotective effect on SSEPs and lipid peroxidation after experimental spinal cord injury

Modeling of Cu oxidation in adiabatic fixed-bed reactor with N2 recycling in a Ca/Cu chemical loop

A dynamic model has been constructed to describe the Cu oxidation reaction within a large-scale Cu/CuO chemical looping process in adiabatic fixed-bed reactors. Careful control of the temperature is required during Cu oxidation because of its high reaction enthalpy. The recycling of a large amount of nitrogen, previously cooled down, and its mixture with air for Cu oxidation regulates the temperature in the reaction front, ensuring that undesirable hot spots that would lead to the irreversible loss of Cu activity are avoided. Since the gas/solid heat exchange front advances faster than the reaction front, the bed is eventually left at a low temperature. An additional stage was added to allow a gas/solid heat exchange between the hot recycled gas and the oxidized bed. This ensures that the fixed-bed is ready for the next reaction step that involves the reduction of CuO by a fuel gas. A sensitivity analysis of the main operating parameters confirms the theoretical viability of this operation. Cu oxidation is favored at high pressure and therefore fast reaction rates were achieved, even with low contents of oxygen in the feed (around 3–4%). The recirculation of more than 80% of the exit gas from the oxidation reactor and its subsequent cooling down to around 423 K keep the maximum temperature down to within reasonable values (1173 K). Although this work was focused on the boundary conditions of the Ca/Cu looping process for hydrogen production and/or power generation, some of the trends observed may be considered valid for other CLC systems that use similar N2 recycles.The authors acknowledge the grant awarded by the Spanish Science and Innovation Ministry under the project ENE2009-11353 and CSIC (201280E017).Peer reviewe

Phosphorus and humic acid application alleviate salinity stress of pepper seedling

Humic acid is a commercial product that contains many elements which improve the soil fertility and increase the availability of nutrient elements. It consequently affects plant growth and yield and ameliorates the deleterious effects of salt stress. The objective of the study was to determine the effect of humic acids and phosphorus on growth and nutrient content of pepper seedlings (cv. Demre) grown under moderate salt stress in growth chamber conditions. Applications of different levels of phosphorus [0 (P0), 50 (P1), 100 (P2) and 150 (P3) mg kg-1] and humic acid [0 (HA0), 750 (HA1) and 1500 (HA2) mg kg-1] to growing media containing moderate salt dose (8 mM NaCl treatment) were studied. The study was replicated four times with 20 plants in each replicate. Humic acid (HA) and phosphorus applications increased the growth and growth parameter of plants. In company, effects of HA and P application was more effective on growth and growth parameter than each separate effect. The optimum total yield was obtained from 69 mg kg-1 P application with HA2 doses according to regression analysis. Humic acid application significantly increased N, P, K, Ca, Mg, S, Mn and Cu contents of shoot of pepper seedling. Also, N, P, K, Ca, S, Fe, Mn, Zn and Cu contents of root were increased with humic acid application. Na contents of both shoot and root of pepper decreased with increased humic acid doses. It can be concluded that high humic acid doses has positive effects on salt tolerance based on the plant growth parameters and nutrient contents. The present study suggests that HA treatments can ameliorate the deleterious effects of salt stress on pepper plants and HA could offer an economical and simple application to reduce problems of pepper production in moderately saline soil.Keywords: Nutrient uptake, plant growth parameter, salt stress, pepperAfrican Journal of Biotechnology Vol. 9(36), pp. 5845-5851, 6 September, 201

New Mediterranean biodiversity records (March 2016)

In this Collective Article on “New Mediterranean Biodiversity Records”, we present additional records of species found in the Mediterranean Sea. These records refer to eight different countries mainly throughout the northern part of the basin, and include 28 species, belonging to five Phyla. The findings per country include the following species: Spain: Callinectes sapidus and Chelidonura fulvipunctata; Monaco: Aplysia dactylomela; Italy: Charybdis (Charybdis) feriata, Carcharodon carcharias, Seriola fasciata, and Siganus rivulatus; Malta: Pomacanthus asfur; Croatia: Lagocephalus sceleratus and Pomadasys incisus; Montenegro: Lagocephalus sceleratus; Greece: Amathia (Zoobotryon) verticillata, Atys macandrewii, Cerithium scabridum, Chama pacifica, Dendostrea cf. folium, Ergalatax junionae, Septifer cumingii, Syphonota geographica, Syrnola fasciata, Oxyu- richthys petersi, Scarus ghobban, Scorpaena maderensis, Solea aegyptiaca and Upeneus pori; Turkey: Lobotes surinamensis, Ruvettus pretiosus and Ophiocten abyssicolum. In the current article, the presence of Taractes rubescens (Jordan & Evermann, 1887) is recorded for the first time in the Mediterranean from Italy. The great contribution of citizen scientists in monitoring biodiversity records is reflected herein, as 10% of the authors are citizen scientists, and contributed 37.5% of the new findings.peer-reviewe