1,371 research outputs found

    SEARCHING FOR PHYSICS BEYOND THE STANDARD MODEL IN ATLAS WITH THE THIRD GENERATION QUARKS

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    ATLAS (A Toroidal LHC Apparatus) is one of the general-purpose detectors at the CERN's Large Hadron Collider (LHC), designed to study proton- proton collisions at a center of mass energy of 14 TeV. This PhD thesis starts with a performance measurement of the Inner Detector, followed by the measurement of an interesting Standard Model process on early data in which tracking and b-tagging play a fundamental role. Finally a search for new physics on the high integrated luminosity sample is presented. It includes a detailed measurement of the tracks impact parameter resolution as a function on the pseudorapidity \u3b7, the pT and the number of hits and shared hits in the silicon detectors of the tracks. The transverse impact parameter is measured to be ~10 \u3bcm for high pT tracks (pT>20 GeV) in a central \u3b7 region with one hit in the innermost pixel layer (b-layer) and without shared hits with other tracks in the silicon detectors. Two measurements are then presented, that profit of this excellent resolution and the related b-tagging performance. The first measurement of the charge asymmetry in the production of top quark pairs in the semileptonic decay channel. A dataset corresponding to an integrated luminosity of 1.04 fb-1, obtained at a centre-of-mass energy of 1as=7 TeV is used. The charge asymmetry is determined using the differential distribution of the reconstructed observable|yt|-|yT|, where yt and yT denote the top and antitop quark rapidities, respectively. The total charge asymmetry after unfolding is measured to be -0.019 \ub1 0.028 (stat.) \ub1 0.024 (syst.) in agreement with the Standard Model prediction of (0.60\ub10.03)%. Finally, the results of a search for direct pair production of supersymmetric partners of the top quark in 4.7 fb-1 and 13.0 fb-1 of integrated luminosity from proton-proton collisions respectively collected at 7 TeV in 2011 and 8 TeV in 2012 are reported. Scalar top quarks decaying into a b-quark and a superymmetric chargino are searched for in events with two leptons in the final state. This events have a final state topology similar that of top-antitop events and this analysis builds up on the experience that I gained with the top-antitop charge asymmetry measurement. No excess above the Standard Model expectation is observed. A scalar top with mass between 150 and 450 GeV is excluded at 95% CL for a chargino approximately degenerate with the scalar top and a massless ligthest neutralino

    Agronomic and chemical characterization of soybean genotypes for human consumption.

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    Soybean (Glycine max (L) Merrill) presents a high level of good quality protein and lipids that consist mainly of unsaturated fatty acids. It also has considerable amounts of B complex vitamins and minerals such as iron, potassium and magnesium (CarrĂŁo-Panizzi, 1987). In addition to these good nutritional characteristics, soybean for human consumption should have a sweet, nut-like flavor, pale colored seeds (tegument, hilum and cotyledon) and suitable seed size for use as food (Destro, 1991; Vello, 1992). This research was carried out to describe the agronomic and chemical characteristics of food-type soybean genotypes for later use as cultivars or in crosses. Seventy-two soybean genotypes were used in the study, and the agronomic quantitative, qualitative and chemical traits of the grains were assessed, including mineral composition, oil, protein, carbohydrates and ash contents. The results showed that there was great genetic diversity among the genotypes studied for all the agronomic characteristics assessed. The F 82-5782 genotype was outstanding, presenting yield compatible with commercial exploitation as well as large seeds. The Mikawashima genotype presented the highest carbohydrate contents, while the Toffumame II genotype showed the greatest P contents and was also among the six genotypes that presented the greatest K, Ca, Mg, S, Zn, Mn and protein values. These genotypes can be used as cultivars or in breeding programs to solve specific problems of nutrient shortage due to genetic traits

    Diet-induced Obesity In Rats Leads To A Decrease In Sperm Motility.

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    Obesity is rapidly becoming a worldwide epidemic that affects children and adults. Some studies have shown a relationship between obesity and infertility, but until now it remains controversial. Thus, the aim of the present study was to investigate the effect of high-fat diet-induced obesity on male reproductive parameters. In a first experiment, male Wistar rats were fed a high-fat diet (HFD) or standard chow (SD) for 15, 30 or 45 weeks, after which they were evaluated by adiposity index, serum leptin levels, reproductive organ weights and sperm counts. In a second experiment, rats received HFD or SD only for 15 weeks, long enough to cause obesity. Sexual hormones and sexual behavior were evaluated in these animals, as well as fertility after natural mating. Another group of rats was submitted to motility analysis and fertility evaluation after in utero insemination. After 15, 30 or 45 weeks, HFD-fed animals presented significant increases in obesity index and serum leptin levels. Reproductive organ weights and sperm counts in the testis and epididymis were similar between the two groups at all timepoints studied. Sexual behavior was not altered by the diet regimen, and HFD fertility after natural mating was also similar to SD-fed animals. Intergroup testosterone levels were also comparable, but estradiol levels were increased in HFD rats. Furthermore, sperm quality was reduced in HFD animals as evidenced by their decreased percentage of sperm with progressive movement. This altered motility parameter was followed by a trend toward reduction in fertility potential after artificial in utero insemination. The results reported herein showed that obesity can affect sperm quality, by reducing sperm motility, without affecting other sperm parameters. The low sperm quality caused a slight reduction in fertility potential, showing that obesity may lead to impairment in male fertility.93

    The ATLAS EventIndex: Full chain deployment and first operation

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    AbstractThe Event Index project consists in the development and deployment of a complete catalogue of events for experiments with large amounts of data, such as the ATLAS experiment at the LHC accelerator at CERN. Data to be stored in the EventIndex are produced by all production jobs that run at CERN or the GRID; for every permanent output file, a snippet of information, containing the file unique identifier and the relevant attributes for each event, is sent to the central catalogue. The estimated insertion rate during the LHC Run 2 is about 80 Hz of file records containing ∌15 kHz of event records. This contribution describes the system design, the initial performance tests of the full data collection and cataloguing chain, and the project evolution towards the full deployment and operation by the end of 2014
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