Towards an Achievable Performance for the Loop Nests

Numerous code optimization techniques, including loop nest optimizations, have been developed over the last four decades. Loop optimization techniques transform loop nests to improve the performance of the code on a target architecture, including exposing parallelism. Finding and evaluating an optimal, semantic-preserving sequence of transformations is a complex problem. The sequence is guided using heuristics and/or analytical models and there is no way of knowing how close it gets to optimal performance or if there is any headroom for improvement. This paper makes two contributions. First, it uses a comparative analysis of loop optimizations/transformations across multiple compilers to determine how much headroom may exist for each compiler. And second, it presents an approach to characterize the loop nests based on their hardware performance counter values and a Machine Learning approach that predicts which compiler will generate the fastest code for a loop nest. The prediction is made for both auto-vectorized, serial compilation and for auto-parallelization. The results show that the headroom for state-of-the-art compilers ranges from 1.10x to 1.42x for the serial code and from 1.30x to 1.71x for the auto-parallelized code. These results are based on the Machine Learning predictions.Comment: Accepted at the 31st International Workshop on Languages and Compilers for Parallel Computing (LCPC 2018

Glutathione-s-transferase pi expression in leukaemia: a comparative analysis with mdr-1 data.

Drug resistance in haemopoietic cells may be partly related to the expression of the glutathione-s-transferase (GST) pi and mdr-1 genes. We have used RNA slot blotting techniques to investigate the expression of GST pi in peripheral blood and bone marrow of eleven normal subjects, nine patients with myelodysplastic syndrome (MDS), eighteen patients with acute myeloblastic leukaemia (AML), and thirty-two patients with chronic lymphocyte leukaemia (CLL). We found increased expression of GST pi in 8 of 9 MDS, (7 peripheral blood, 1 bone marrow) 12 of 18 AML (5 peripheral blood, 7 bone marrow; 4 of 5 untreated, 1 of 5 secondary, 7 of 11 relapse or refractory) and in the peripheral blood of 24 of 32 CLL (3 of 7 untreated, 21 of 25 treated) relative to normal controls. Increased expression of GST pi can occur at any stage of disease and shows no clear relation to mdr-1 expression except, possibly, in CLL. In 3 AML patients GST pi transcript levels were the same or lower on relapse compared to presentation. Upregulation of the GST pi gene could not be demonstrated in 2 CLL patients in response to treatment with intermittent chlorambucil

Desenvolvimento de novas linhagens de mamoeiro com auxílio de marcadores microssatélites.

O mamoeiro apresenta sistema reprodutivo bastante diversificado, podendo haver genótipos dióicos com reprodução por alogamia e genótipos ginóico-andromonóicos com autogamia facultativa. Este último tipo é o que predomina nos cultivos comerciais em função da preferência do mercado consumidor por frutos oriundos de plantas hermafroditas. Portanto, as ações de melhoramento visando o desenvolvimento de novas variedades são realizadas em populações ginóico-andromonóicas.PDF. T26

Influence of Fluorination on the Solubilities of Carbon Dioxide, Ethane, and Nitrogen in 1‑n‑Fluoro-alkyl-3-methylimidazolium Bis(n‑fluoroalkylsulfonyl)amide Ionic Liquids

International audienceThe effect on gas solubilities of adding partially fluorinated alkyl side chains either on imidazolium-based cations or on bis(perfluoroalkylsulfonyl)amide anions was studied. The aim was to gain knowledge of the mechanisms of dissolution of gases in fluorinated ionic liquids and, if possible, to improve physical absorption of carbon dioxide in ionic liquids. We have determined experimentally, in the temperature range of 298–343 K and at pressures close to atmospheric pressure, the solubility and thermodynamics of solvation of carbon dioxide, ethane, and nitrogen in the ionic liquids 1-octyl-3-methylimidazolium bis[trifluoromethylsulfonyl]amide ([C8mim][NTf2]), 1-octyl-3-methylimidazolium bis[pentafluoroethylsulfonyl]amide ([C8mim][BETI]), 1-(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)-3-methylimidazolium bis[trifluoromethylsulfonyl]amide ([C8H4F13mim][NTf2]), and 1-(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)-3-methylimidazolium bis[pentafluoroethylsulfonyl]amide ([C8H4F13mim][BETI]). Ionic liquids with partial fluorination on the cation were found to exhibit higher carbon dioxide and nitrogen mole fraction solubilities but lower ethane solubilities, compared to those of their hydrogenated counterparts. Molecular simulation provided insights about the mechanisms of solvation of the different gases in the ionic liquids