312 research outputs found

    Correlated variability of Mkn 421 at X-ray and TeV wavelengths on timescales of hours

    Get PDF
    Mkn 421 was observed for about two days with BeppoSAX, prior to and partly overlapping the start of a 1 week continuous exposure with ASCA in April 1998, as part of a world-wide multiwavelength campaign. A pronounced, well defined, flare observed in X-rays was also observed simultaneously at TeV energies by the Whipple Observatory's 10 m gamma-ray telescope. These data provide the first evidence that the X-ray and TeV intensities are well correlated on time-scales of hours.Comment: 4 pages, 1 figure, presented at the VERITAS Workshop on the TeV Astrophysics of Extragalactic Object

    Gamma-Hadron Separation Methods for the VERITAS Array of Four Imaging Atmospheric Cherenkov Telescopes

    Get PDF
    Ground-based arrays of imaging atmospheric Cherenkov telescopes have emerged as the most sensitive gamma-ray detectors in the energy range of about 100 GeV and above. The strengths of these arrays are a very large effective collection area on the order of 100,000 square meter, combined with excellent single photon angular and energy resolutions. The sensitivity of such detectors is limited by statistical fluctuations in the number of Cosmic Ray initiated air showers that resemble gamma-ray air showers in many ways. In this paper, we study the performance of simple event reconstruction methods when applied to simulated data of the Very Energetic Radiation Imaging Telescope Array System (VERITAS) experiment. We review methods for reconstructing the arrival direction and the energy of the primary photons, and examine means to improve on their performance. For a software threshold energy of 300 GeV (100 GeV), the methods achieve point source angular and energy resolutions of sigma[63%]= 0.1 degree (0.2 degree) and sigma[68%]= 15% (22%), respectively. The main emphasis of the paper is the discussion of gamma-hadron separation methods for the VERITAS experiment. We find that the information from several methods can be combined based on a likelihood ratio approach and the resulting algorithm achieves a gamma-hadron suppression with a quality factor that is substantially higher than that achieved with the standard methods used so far.Comment: Astroparticle Physics, in press, 22 pages, 10 figure

    The First VERITAS Telescope

    Full text link
    The first atmospheric Cherenkov telescope of VERITAS (the Very Energetic Radiation Imaging Telescope Array System) has been in operation since February 2005. We present here a technical description of the instrument and a summary of its performance. The calibration methods are described, along with the results of Monte Carlo simulations of the telescope and comparisons between real and simulated data. The analysis of TeV Îł\gamma-ray observations of the Crab Nebula, including the reconstructed energy spectrum, is shown to give results consistent with earlier measurements. The telescope is operating as expected and has met or exceeded all design specifications.Comment: Accepted by Astroparticle Physic

    An Integrated TCGA Pan-Cancer Clinical Data Resource to Drive High-Quality Survival Outcome Analytics

    Get PDF
    For a decade, The Cancer Genome Atlas (TCGA) program collected clinicopathologic annotation data along with multi-platform molecular profiles of more than 11,000 human tumors across 33 different cancer types. TCGA clinical data contain key features representing the democratized nature of the data collection process. To ensure proper use of this large clinical dataset associated with genomic features, we developed a standardized dataset named the TCGA Pan-Cancer Clinical Data Resource (TCGA-CDR), which includes four major clinical outcome endpoints. In addition to detailing major challenges and statistical limitations encountered during the effort of integrating the acquired clinical data, we present a summary that includes endpoint usage recommendations for each cancer type. These TCGA-CDR findings appear to be consistent with cancer genomics studies independent of the TCGA effort and provide opportunities for investigating cancer biology using clinical correlates at an unprecedented scale. Analysis of clinicopathologic annotations for over 11,000 cancer patients in the TCGA program leads to the generation of TCGA Clinical Data Resource, which provides recommendations of clinical outcome endpoint usage for 33 cancer types

    Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

    Get PDF
    A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

    Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC

    Get PDF
    Measurements of inclusive jet suppression in heavy ion collisions at the LHC provide direct sensitivity to the physics of jet quenching. In a sample of lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the anti-kt algorithm with values for the distance parameter that determines the nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp. Jet production is found to be suppressed by approximately a factor of two in the 10% most central collisions relative to peripheral collisions. Rcp varies smoothly with centrality as characterized by the number of participating nucleons. The observed suppression is only weakly dependent on jet radius and transverse momentum. These results provide the first direct measurement of inclusive jet suppression in heavy ion collisions and complement previous measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables, submitted to Physics Letters B. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02

    Pengaruh Pemberian Ketotifen terhadap Jumlah Sel Fibroblas dan Kepadatan Sel Kolagen pada Luka Insisi Tikus Wistar

    Get PDF
    Ingga Hadian, S-501202027. PENGARUH PEMBERIAN KETOTIFEN TERHADAP JUMLAH SEL FIBROBLAS DAN KEPADATAN SEL KOLAGEN PADA LUKA INSISI TIKUS WISTAR. Pembimbing I : DR. Untung Alfianto, dr, Sp.Bs, Pembimbing II : dr. Ardana Tri Arianto. Msi. Med. Sp.An-KNA. Program studi Magister Kedokteran Keluarga, Minat Utama Ilmu Biomedik, Fakultas Kedokteran Universitas Sebelas Maret, Surakarta, 2016. Latar Belakang : Sel mast merupakan salah satu yang berperan dalam proses inflamasi pada penyembuhan luka. Sel mast dikaitkan dengan kejadian luka kronis, sehingga sel mast diduga ikut memelihara proses inflamasi secara berlebihan. Hambatan pada degranulasi sel mast diharapkan akan mempercepat penyembuhan luka yang ditandai dengan meningkatnya jumlah sel fibroblas dan kepadatan sel kolagen. Ketotifen mampu mengurangi dreganulasi sel Mast dan mengurangi pelepasan Histamin, protease sel Mast, myeloperoxidase, leukotriens, PAF dan bermacam-macam Prostaglandin. Ketotifen juga menghambat agregasi polimorfonuklear serta mengurangi respon inflamasi dan mempercepat migrasi fibroblas di fase proliferasi. Tujuan :Mengetahui perbedaan jumlah sel fibroblas dan kepadatan sel kolagen pada tikus wistar yang diberikan Ketotifen oral dosis 0.3 mg/kg dibandingkan plasebo pada penyembuhan luka insisi tikus wistar. Metode : Penelitian ini termasuk true eksperimental laboratorik dengan desain Randomized Controlled Trial yang menggunakan tikus wistar sebagai obyek penelitian. 14 tikus Wistar dibagi dalam 2 kelompok, masing masing kelompok terdiri atas 7 tikus Wistar. Kelompok 1 merupakan kelompok kontrol yang dilakukan insisi sepanjang 2cm pada kulit punggung tikus dan diberikan plasebo per oral selama 6 hari. Kelompok 2 merupakan kelompok perlakuan yang dilakukan insisi sepanjang 2cm pada kulit punggung tikus dan diberikan Ketotifen 0,3 mg/kgBB per oral setiap 12 jam selama 6 hari. Analisis data untuk membandingkan rerata antar kedua kelompok yaitu kelompok perlakuan dan kelompok kontrol menggunakan uji independent samples t-test, dengan tingkat kemaknaan p < 0,05 (dikatakan bermakna secara statistik). Hasil : Pada kelompok kontrol didapatkan rerata persentase kepadatan sel kolagen sebesar 26,05 %, sedangkan pada kelompok Ketotifen didapatkan rerata persentase kepadatan sel kolagen sebesar 36,13 %. Untuk jumlah sel fibroblas pada kelompok kontrol didapatkan rerata sebesar 423 per lapang pandang, sedangkan pada kelompok Ketotifen didapatkan rerata sebesar 555,43 per lapang pandang. Kesimpulan : Ketotifen mempercepat penyembuhan luka ditandai dengan peningkatan sel fibroblas dan sel kolagen. Kata Kunci : Sel Mast, Ketotifen, Sel fibroblas, Serabut Kolagen. ABSTRACT Ingga Hadian, S-501202027. EFFECTS OF KETOTIFEN ON FIBROBLAST CELL COUNT AND COLLAGEN DENSITY ON INCISED WISTAR RATS. DR. Untung Alfianto, dr., Sp.BS, dr. Ardana Tri Arianto, Msi, Med, Sp.An-KNA. Background: Mast cells have a pivotal role in every healing process that involves inflammation of the cells, usually in wounds of chronic nature. If the degranulation process of the mast cells are inhibited, the healing process of the wound will accelerate, indicated by a raise in fibroblast cells and collagen density. Ketotifen are shown to inhibit the degranulation process and decreasing the release of histamin, mast cells proteases, myeloperoxidases, leukotriens, PAF, and various prostaglandins. Ketotifen can also inhibit the aggregation of polymorphonuclear cells, increasing the rate of fibroblast migration in the proliferation phase. This study was aimed to identify the effects of ketotifen on fibroblast cell count and collagen density tested on a wistar rats model. Methods: This study was a true laboratoric experimental study with randomized controlled trial using wistar rats model as objects. 14 rats were divided into two groups, each group contained seven rats. The first group was the control group, where the rats were incised 2 cm above the back skin, and were given per oral placebo for 6 days. The second group were given the same treatment, only the rats were given ketotifen 0.3 mg/kg per oral, every 12 hours lasting 6 days. The data were then collected and tested with independent sample t-test, with p value less than 0,05 is statistically significant. Results: In the control group, the mean percentage of the thickest collagen density were marked at 26.05%, whereas in the treatment group collagen density were marked at 36.13%. The mean fibroblast cell count were marked at 423 and 555.43 each viewing field, on the control group and the treatment group respectively. Conclusion: Ketotifen can accelerate the healing process, marked by the significant increase in collagen density and fibroblast cell count. Keywords: mast cells, ketotifen, fibroblast cells, collagen fibers

    Measurement of event-shape observables in Z→ℓ+ℓ− events in pp collisions at √ s=7 TeV with the ATLAS detector at the LHC

    Get PDF
    Event-shape observables measured using charged particles in inclusive ZZ-boson events are presented, using the electron and muon decay modes of the ZZ bosons. The measurements are based on an integrated luminosity of 1.1fb−11.1 {\rm fb}^{-1} of proton--proton collisions recorded by the ATLAS detector at the LHC at a centre-of-mass energy s=7\sqrt{s}=7 TeV. Charged-particle distributions, excluding the lepton--antilepton pair from the ZZ-boson decay, are measured in different ranges of transverse momentum of the ZZ boson. Distributions include multiplicity, scalar sum of transverse momenta, beam thrust, transverse thrust, spherocity, and F\mathcal{F}-parameter, which are in particular sensitive to properties of the underlying event at small values of the ZZ-boson transverse momentum. The Sherpa event generator shows larger deviations from the measured observables than Pythia8 and Herwig7. Typically, all three Monte Carlo generators provide predictions that are in better agreement with the data at high ZZ-boson transverse momenta than at low ZZ-boson transverse momenta and for the observables that are less sensitive to the number of charged particles in the event.Comment: 36 pages plus author list + cover page (54 pages total), 14 figures, 4 tables, submitted to EPJC, All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2014-0

    Operation and performance of the ATLAS semiconductor tracker

    Get PDF
    The semiconductor tracker is a silicon microstrip detector forming part of the inner tracking system of the ATLAS experiment at the LHC. The operation and performance of the semiconductor tracker during the first years of LHC running are described. More than 99% of the detector modules were operational during this period, with an average intrinsic hit efficiency of (99.74±0.04)%. The evolution of the noise occupancy is discussed, and measurements of the Lorentz angle, Ύ-ray production and energy loss presented. The alignment of the detector is found to be stable at the few-micron level over long periods of time. Radiation damage measurements, which include the evolution of detector leakage currents, are found to be consistent with predictions and are used in the verification of radiation background simulations

    Measurement of the View the tt production cross-section using eÎŒ events with b-tagged jets in pp collisions at √s = 13 TeV with the ATLAS detector

    Get PDF
    This paper describes a measurement of the inclusive top quark pair production cross-section (σttÂŻ) with a data sample of 3.2 fb−1 of proton–proton collisions at a centre-of-mass energy of √s = 13 TeV, collected in 2015 by the ATLAS detector at the LHC. This measurement uses events with an opposite-charge electron–muon pair in the final state. Jets containing b-quarks are tagged using an algorithm based on track impact parameters and reconstructed secondary vertices. The numbers of events with exactly one and exactly two b-tagged jets are counted and used to determine simultaneously σttÂŻ and the efficiency to reconstruct and b-tag a jet from a top quark decay, thereby minimising the associated systematic uncertainties. The cross-section is measured to be: σttÂŻ = 818 ± 8 (stat) ± 27 (syst) ± 19 (lumi) ± 12 (beam) pb, where the four uncertainties arise from data statistics, experimental and theoretical systematic effects, the integrated luminosity and the LHC beam energy, giving a total relative uncertainty of 4.4%. The result is consistent with theoretical QCD calculations at next-to-next-to-leading order. A fiducial measurement corresponding to the experimental acceptance of the leptons is also presented
    • 

    corecore