4,776 research outputs found

    Jet Production in proton-proton collisions at sqrt(s) =7 TeV with the ATLAS experiment

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    We report on the first measurements done with the ATLAS experiment of the characteristics of energetic jets produced in proton-proton collisions at the center of mass energy of 7 TeV. Jets are reconstructed using the anti-kt clustering algorithm with distance parameter R=0.6. The kinematic region investigated in this paper corresponds to jets with transverse momentum p_T>30$GeV and rapidity |y_jet |<2.8. A critical understanding of the jet production is obtained by comparing the data to predictions based on leading-order QCD matrix elements plus parton shower Monte Carlo simulated events. The results shown are obtained on a data sample corresponding to about 1 nb**-1 of integrated luminosity delivered by the Large Hadron Collider.Comment: 4 pages, Presented at QCD10 - 15th International QCD Conference, Montpellier (France), 28th June-3rd Jul

    Association between Teachers’ Selflessness and School Organizational Commitment

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    This study aimed to determine the relationship between teachers' selflessness on their school organizational commitment. The study employed a descriptive-correlation research design with the online survey as the primary data collection tool. The respondents came from the 30 elementary and secondary schools in the Schools Division Office, Central Luzon. One hundred fifty-one public school teachers participated in the online survey using a stratified sampling technique. Adapted questionnaires were used to gather data. For the statistical treatment of the study, the mean was used for the teachers' responses. In contrast, for the relationship, the study used Pearson r-correlation. The study found that teachers' selflessness described their philosophies as "agree." As for the teachers' organizational commitment, it generated moderate to high responses. There is a significant difference in teachers' selflessness regarding sex and position. Also, the study found a relationship between teachers' selflessness, and affective and continuance commitment aspects of teachers' organizational commitment. Based on the results mentioned above, the researcher provided some crucial recommendations for the study

    Determination of free and amidated bile acids by high-performance liquid chromatography with evaporative light-scattering mass detection

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    A simple reverse phase high-performance liquid chromatographic method for a simultaneous analysis of free, glycine- and taurine-amidated bile acids is described. The resolution of ursodeoxycholic, cholic, chenodeocycholic, deoxycholic, and lithocholic acids, either free or amidated with glycine and taurine, is achieved using a C-18 octadecylsilane column (30 cm length, 4 micron particle size) with a gradient elution of aqueous methanol (65‚ÄĒ-75%) containing 15 mM ammonium acetate, pH 5.40, at 37 degrees C. The separated bile acids are detected with a new evaporative light-scattering mass detector and by absorbance at 200 nm. A complete resolution of the 16 bile acids, including the internal standard nor-deoxycholic acid, is obtained within 55 min. Using the light-scattering mass detector, amidated bile acids and, for the first time, free bile acids can be detected with similar detection limits in the order of 2-7 nmol. The new detector improves the baseline and the signal-to-noise ratio over the UV detection as it is not affected by impurities present in the samples with higher molar absorptivity than bile acids or by the change in the mobile phase composition during the gradient. The method fulfills all the standard requirements of precision and accuracy and the linearity of the mass detector is over 5 decade the detection limit. The new method has been used for the direct analysis of bile acid in stools and bile with only a preliminary clean-up procedure using a C-18 reverse phase extraction

    A device to characterize optical fibres

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    ATLAS is a general purpose experiment approved for the LHC collider at CERN. An important component of the detector is the central hadronic calorimeter; for its construction more than 600,000 Wave Length Shifting (WLS) fibres (corresponding to a total length of 1,120 Km) have been used. We have built and put into operation a dedicated instrument for the measurement of light yield and attenuation length over groups of 20 fibres at a time. The overall accuracy achieved in the measurement of light yield (attenuation length) is 1.5% (3%). We also report the results obtained using this method in the quality control of a large sample of fibres.Comment: 17 pages 20 figeres submitted to NIM journa

    Protein Microdeposition Using a Conventional Ink-Jet Printer

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    Many recent bioanalytical systems based on immunologic and hybridization reactions in a mono- or bidimensional microarray format require technology that can produce arrays of spots containing biospecific molecules. Some microarray deposition instruments are commercially available, and other devices have been described in recent papers. We describe a system obtained by adapting a commercial ink-jet printer and used to produce mono- and bidimensional arrays of spots containing horseradish peroxidase on cellulose paper. In a few minutes, it was possible to obtain bidimensional arrays containing several thousands of spots with a diameter as low as 0.2 mm, with each of which requiring only a few nanoliters of the enzyme deposition solution. The quantity of enzyme in each spot was evaluated with a chemiluminescent reaction and a charge-coupled device-based, low-light imaging luminograph. The chemiluminescence measurements revealed that the reproducibility of the enzyme deposition was satisfactory for analytical purposes, with the variation coefficients being lower than 10% in almost all cases

    Exploring Proprotein Convertase Subtilisin/Kexin 9 (PCSK9) Autoproteolysis Process by Molecular Simulations: Hints for Drug Design

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    Proprotein convertase subtilisin/kexin 9 (PCSK9) is a notable target for the treatment of hypercholesterolemia because it regulates the population of the low-density lipoprotein receptor (LDLR) on liver cells. The PCSK9 zymogen is a serine protease that spontaneously undergoes a double self-cleavage step. The available X-ray structures depict the PCSK9 mature state, but the atomic details of the zymogen state of the enzyme are still unknown. Additionally, why the protease activity of PCSK9 is blocked after the second autoprocessing step remains unclear, as this deviates from other members of the PCSK family. By performing constant-pH molecular dynamics (MD) simulations, we investigated the protonation state of the catalytic triad of PCSK9 and found that it strongly influences the catalytic properties of the enzyme. Moreover, we determined the final step of the maturation process by classical and steered MD simulations. This study could facilitate the identification of ligands capable of interfering with the PCSK9 maturation process

    New Insights into Bile Acids Related Signaling Pathways in the Onset of Colorectal Cancer

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    Colorectal cancer (CRC) ranks as the second among the causes of tumor death worldwide, with an estimation of 1.9 million new cases in 2020 and more than 900,000 deaths. This rate might increase by 60% over the next 10 years. These data are unacceptable considering that CRC could be successfully treated if diagnosed in the early stages. A high-fat diet promotes the hepatic synthesis of bile acids (BAs) increasing their delivery to the colonic lumen and numerous scientific reports correlate BAs, especially secondary BAs, with CRC incidence. We reviewed the physicochemical and biological characteristics of BAs, focusing on the major pathways involved in CRC risk and progression. We specifically pointed out the role of BAs as signaling molecules and the tangled relationships among their nuclear and membrane receptors with the big bang of molecular and cellular events that trigger CRC occurrence
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