154 research outputs found

    Photoperiod Effect on Fecundity, Longevity and Sex ratio of Trichogramma brassicae (Hym: Trichogrammatidae)

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    The effect of photoperiod on parasitization of the eggs of Ephestia kuehniella Zeller (Lep: Pyralidae) by Trichogramma brassicae Bezdenko (Hym: Trichogrammatidae) was investigated under several photoperiodic regimes of L: D = 0: 24, 3: 21, 6: 18, 9: 15, 12: 12, 15: 9, 18: 6, 21: 3 and absolute light on. Fecundity of T. brassicae females (the number of parasitized E. kuehniella eggs) was independent of photoperiod in the whole life time of females. However, photoperiod had a significant influence on the longevity of T. brassicae females. The least fecundity and longevity was for those that developed and were kept under 18L: 6D and the highest fecundity and longevity was for those that developed and were kept under 21L: 3D and absolute darkness, respectively. On the other hand, the proportion of T. brassicae females was dependent of photoperiod and the highest proportion of females was observed under 18L: 6D. It seems that long term photoperiods may stimulate a particular gland to secret a special hormone which results in more longevity and female proportion of parasitoid. As a conclusion, long term photoperiods may improve efficiency of the parasitoid by increasing longevity and sex ratio

    The effect of interaguild predation on avoidance behavior of the aphidophagous midge, Aphidoletes aphidimyza (Dip.: Cecidomyiidae) on its encounter with the predatory bug Orius laevigatus (Het.: Anthocoridae)

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    The predatory bug, Orius laevigatus (Fibber), and the predatory midge, Aphidoletes aphidimyza Rondani, belong to an aphidophagous guild, feeding on the cotton aphid Aphis gossypii Glover. In this study some avoidance behavior of the predatory midge such as dropping from the plant and choosing an oviposition site in the face of interaguild (IG) predator O. laevigatus are investigated. The results indicate that A. aphidimyza females prefer not to lay eggs when they discover that their offspring would be at risk of being attacked by the IG predator. The experiment also shows that the dropping behavior of predatory midge larva, upon being spotted by the predatory bug (44.5%), is significantly higher than the control (6.5%). Both the dropping behavior and mortality of IG prey are found to be influenced by all developmental stages of the cotton aphid. The percentage of mortality and dropping rates of A. aphidimyza larvae in the presence of 2nd instar nymphs of aphids were 10% and 12.5% and for 4th instar nymphs were 31% and 44.5%, respectively. These findings confirm the correlation between habitat choice of A. aphidimyza, in relation to predation risk for its offspring, and also underscore the population structure of prey for avoidance behavior strategy of the aphidophagous midge in an interaguild predation system

    Fitness costs of cornicle secretions as a defense mechanism for cotton aphid, Aphis gossypii (Hem.: Aphididae)

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    The cornicle secretion is a defensive mechanism in many aphid species to warn the related individuals of predation by natural enemies. Many researches have been conducted on the benefits of cornicle droplet and alarm pheromone but the cost of this phenomenon is poorly investigated. This study is intended to evaluate the direct fitness cost of cornicle secretion of immature as well as mature cotton aphids, Aphis gossypii Glover. Aphids were artificially forced to produce cornicle droplets at different stages of their development (second, third and fourth instars as well as adults). They were lightly stroked on the anterior portion of the thorax with a fine brush, resulting in the secretion of visible cornicle droplets. After this manipulation, life-history parameters of aphids were recorded until the death of the last adult individual. Experiments were conducted in a growth chamber at 25 ± 1°C, 50 ± 5% RH and a photoperiod of 16 L: 8 D hours. The results showed that the secretion of cornicle droplets by second and third instar nymphs of cotton aphid did not affect their survivorship and the number of offspring produced by their adult stage. In contrast, fourth instar nymphs as well as adults that emitted cornicle droplets had significantly lower survivorship and offspring production than non-secretors. The cornicle secretion has also fitness costs on the late instar and adult cotton aphids

    Towards an Achievable Performance for the Loop Nests

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    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

    High-resolution stratigraphy of the Changhsingian (Late Permian) successions of NW Iran and the Transcaucasus based on lithological features, conodonts and ammonoids

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    The Permian–Triassic boundary sections in north-western Iran belong to the most complete successions, in which the largest mass extinction event in the history of the Earth can be studied. We investigated the Changhsingian stage in six sections in the area of Julfa (Aras Valley) for their lithology, conodonts and ammonoids. Revision of the biostratigraphy led to the separation of 10 conodont zones (from bottom to top Clarkina orientalis–C. subcarinata interval zone, C. subcarinata, C. changxingensis, C. bachmanni, C. nodosa, C. yini, C. abadehensis, C. hauschkei, Hindeodus praeparvus–H. changxingensis and Merrilina ultima–Stepanovites ?mostleri zones) and 8 ammonoid zones (from bottom to top Iranites transcaucasius–Phisonites triangulus, Dzhulfites nodosus, Shevyrevites shevyrevi, Paratirolites trapezoidalis, P. waageni, Stoyanowites dieneri, Abichites stoyanowi and Arasella minuta zones). The new ammonoid genera Stoyanowites and Arasella are described

    Investigation of presence, distribution and flight period of oak leaf roller moth, Tortrix viridana (Lep.: Tortricidae) using pheromone traps in Kurdistan province

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    Forests cover about 5,200,000 hectares of the west of Iran, from which 500,000 hectares are located in Kurdistan province. One of the most important pests in the oak forests of this province is oak leaf roller moth, Tortrix viridana L. (Lep.: Tortricidae). This pest significantly damages the oak forest each year. Using pheromone trap is one of the suitable methods for monitoring of this pest. In this work, distribution and flight period of the pest were studied by pheromone traps during two years. Fifteen regions were trapped at the equal distances (40 km) from Kamyaran (south west of Kurdistan province) to Baneh (north west of Kurdistan province) to investigate the presence and distribution of this moth. Also, a region located between Sanandaj and Marivan was selected to study the flight period. Some traps were established in this region and checked every two days. Investigation of pest distribution showed that oak leaf roller moth was present all over the sites from Kamyaran to Baneh. Different populations of moth were trapped in all over the sites. The highest population was trapped in Colit region (mid-west of Kurdistan province). The study of flight period showed that first moths were trapped on May, 16th and the peak of the flight took place on May, 21st and finally the last moths were trapped on June, 24th. Therefore, adults activated during 40 days; mating and oviposition occurred during this period. Incubation period lasted 9 months and activation of larvae was coincident with flashing of foliar buds

    Defining KIR and HLA Class I Genotypes at Highest Resolution via High-Throughput Sequencing.

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    The physiological functions of natural killer (NK) cells in human immunity and reproduction depend upon diverse interactions between killer cell immunoglobulin-like receptors (KIRs) and their HLA class I ligands: HLA-A, HLA-B, and HLA-C. The genomic regions containing the KIR and HLA class I genes are unlinked, structurally complex, and highly polymorphic. They are also strongly associated with a wide spectrum of diseases, including infections, autoimmune disorders, cancers, and pregnancy disorders, as well as the efficacy of transplantation and other immunotherapies. To facilitate study of these extraordinary genes, we developed a method that captures, sequences, and analyzes the 13 KIR genes and HLA-A, HLA-B, and HLA-C from genomic DNA. We also devised a bioinformatics pipeline that attributes sequencing reads to specific KIR genes, determines copy number by read depth, and calls high-resolution genotypes for each KIR gene. We validated this method by using DNA from well-characterized cell lines, comparing it to established methods of HLA and KIR genotyping, and determining KIR genotypes from 1000 Genomes sequence data. This identified 116 previously uncharacterized KIR alleles, which were all demonstrated to be authentic by sequencing from source DNA via standard methods. Analysis of just two KIR genes showed that 22% of the 1000 Genomes individuals have a previously uncharacterized allele or a structural variant. The method we describe is suited to the large-scale analyses that are needed for characterizing human populations and defining the precise HLA and KIR factors associated with disease. The methods are applicable to other highly polymorphic genes.This study was supported by U.S. National Institutes of Health grants U01 AI090905, R01 20 GM109030, R01 AI17892 and U19 AI119350. Authors Steven Norberg and Mostafa Ronaghi are 21 employees of Illumina Inc.This is the author accepted manuscript. It is currently under an indefinite embargo pending publication by Elsevier

    The PERSIANN family of global satellite precipitation data: a review and evaluation of products

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    Over the past 2 decades, a wide range of studies have incorporated Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks (PERSIANN) products. Currently, PERSIANN offers several precipitation products based on different algorithms available at various spatial and temporal scales, namely PERSIANN, PERSIANN-CCS, and PERSIANN-CDR. The goal of this article is to first provide an overview of the available PERSIANN precipitation retrieval algorithms and their differences. Secondly, we offer an evaluation of the available operational products over the contiguous US (CONUS) at different spatial and temporal scales using Climate Prediction Center (CPC) unified gauge-based analysis as a benchmark. Due to limitations of the baseline dataset (CPC), daily scale is the finest temporal scale used for the evaluation over CONUS. Additionally, we provide a comparison of the available products at a quasi-global scale. Finally, we highlight the strengths and limitations of the PERSIANN products and briefly discuss expected future developments.</p

    Perovskite CIGS Tandem Solar Cells From Certified 24.2 toward 30 and Beyond

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    We demonstrate a monolithic perovskite CIGS tandem solar cell with a certified power conversion efficiency PCE of 24.2 . The tandem solar cell still exhibits photocurrent mismatch between the subcells; thus optical simulations are used to determine the optimal device stack. Results reveal a high optical potential with the optimized device reaching a short circuit current density of 19.9 mA cm 2 and 32 PCE based on semiempirical material properties. To evaluate its energy yield, we first determine the CIGS temperature coefficient, which is at amp; 8722;0.38 K 1 notably higher than the one from the perovskite subcell amp; 8722;0.22 K 1 , favoring perovskite in the field operation at elevated cell temperatures. Both single junction cells, however, are significantly outperformed by the combined tandem device. The enhancement in energy output is more than 50 in the case of CIGS single junction device. The results demonstrate the high potential of perovskite CIGS tandem solar cells, for which we describe optical guidelines toward 30 PC
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