1,987 research outputs found

    Black holes and gravitational waves in string cosmology

    Get PDF
    Pre--big bang models of inflation based on string cosmology produce a stochastic gravitational wave background whose spectrum grows with decreasing wavelength, and which may be detectable using interferometers such as LIGO. We point out that the gravitational wave spectrum is closely tied to the density perturbation spectrum, and that the condition for producing observable gravitational waves is very similar to that for producing an observable density of primordial black holes. Detection of both would provide strong support to the string cosmology scenario.Comment: 6 pages RevTeX fil

    Detection of freeze injury in oranges using magnetic resonance imaging under motion conditions

    Full text link
    Magnetic resonance imaging (MRI) is applied for on-line inspection of fruits. The aim of this work is to address the applicability of MRI for freeze injury detection in oranges directly on a distribution chain. Undamaged and damaged oranges are conveyed at 50 and 100 mm/s by a specially designed conveyor within a 4.7 T spectrometer obtaining fast low-angle shot images. An automatic segmentation algorithm is proposed that allows the discrimination between undamaged and damaged orange

    VME indicator species collected during exploratory fishing in Macaronesian seamounts

    Get PDF
    During the second half of 2012, the longline vessel MARANSA completed 13 fishing trips in international waters of CECAF Area (Division FAO 34), in nine Seamounts from northeast off Madeira (Lion, Ampere, Unicorn, Seine, “Camaguay”, “Cabezos”, Dacia and “Fantasma”) to south off the Canary Islands (Eco/Endeavour), between latitudes 19°N and 35°N, using bottom longlines. The main target species were demersal species such as Wreckfish (Polyprion americanus) or Splendidalfonsino (Beryx splendens). An observer on board recorded the bycatch of Vulnerable Marine Ecosystems (VME) indicator species in order to evaluate the potential adverse impact of bottom fishing activities on VME and samples of the specimens for later identification in the laboratory were stored. The main indicator species found were cold-water corals (black corals, scleractinians and gorgonians) and sponges, species broadly associated with seamounts. The shallower banks, Ampere and Dacia in the north and centre of the area, show the greater biodiversity and the higher percentage of presence of VME indicator species (52% and 53% of the sets respectively), followed by Endeavour (South of the Canary Islands), 36.4%. In these three banks the species distribution is strongly related to depth, finding Antipatharia (mainly Stichopathes sp) and Scleractinia (Dendrophyllia cornigera and D. ramea) in shallower depths and Porifera (Neophryssospongia nolitangere, Leiodermatium lynceus and Asconema setubalense) in deeper bottoms. Species of the Porifera group are present in all banks except of so-called ”Cabezos”

    Temperature and Density Effects on the Nucleon Mass Splitting

    Get PDF
    The finite temperature and finite density dependence of the neutron-proton mass difference is analysed in a purely hadronic framework where the ρω\rho-\omega mixing is crucial for this isospin symmetry breakdown. The problem is handled within Thermo Field Dynamics. The present results, consistent with partial chiral and charge symmetry restoration, improve the experimental data fit for the energy difference between mirror nuclei.Comment: 17 pages, revtex fil

    Radiation Campaign of HPK Prototype LGAD sensors for the High-Granularity Timing Detector (HGTD)

    Full text link
    We report on the results of a radiation campaign with neutrons and protons of Low Gain Avalanche Detectors (LGAD) produced by Hamamatsu (HPK) as prototypes for the High-Granularity Timing Detector (HGTD) in ATLAS. Sensors with an active thickness of 50~μ\mum were irradiated in steps of roughly 2×\times up to a fluence of 3×1015 neqcm23\times10^{15}~\mathrm{n_{eq}cm^{-2}}. As a function of the fluence, the collected charge and time resolution of the irradiated sensors will be reported for operation at 30-30^{\circ}

    Evolution after Anti-TNF Discontinuation in Patients with Inflammatory Bowel Disease: A Multicenter Long-Term Follow-Up Study

    Get PDF
    OBJECTIVES:The aims of this study were to assess the risk of relapse after discontinuation of anti-tumor necrosis factor (anti-TNF) drugs in patients with inflammatory bowel disease (IBD), to identify the factors associated with relapse, and to evaluate the overcome after retreatment with the same anti-TNF in those who relapsed.METHODS:This was a retrospective, observational, multicenter study. IBD patients who had been treated with anti-TNFs and in whom these drugs were discontinued after clinical remission was achieved were included.RESULTS:A total of 1, 055 patients were included. The incidence rate of relapse was 19% and 17% per patient-year in Crohn''s disease and ulcerative colitis patients, respectively. In both Crohn''s disease and ulcerative colitis patients in deep remission, the incidence rate of relapse was 19% per patient-year. The treatment with adalimumab vs. infliximab (hazard ratio (HR)=1.29; 95% confidence interval (CI)=1.01-1.66), elective discontinuation of anti-TNFs (HR=1.90; 95% CI=1.07-3.37) or discontinuation because of adverse events (HR=2.33; 95% CI=1.27-2.02) vs. a top-down strategy, colonic localization (HR=1.51; 95% CI=1.13-2.02) vs. ileal, and stricturing behavior (HR=1.5; 95% CI=1.09-2.05) vs. inflammatory were associated with a higher risk of relapse in Crohn''s disease patients, whereas treatment with immunomodulators after discontinuation (HR=0.67; 95% CI=0.51-0.87) and age (HR=0.98; 95% CI=0.97-0.99) were protective factors. None of the factors were predictive in ulcerative colitis patients. Retreatment of relapse with the same anti-TNF was effective (80% responded) and safe.CONCLUSIONS:The incidence rate of inflammatory bowel disease relapse after anti-TNF discontinuation is relevant. Some predictive factors of relapse after anti-TNF withdrawal have been identified. Retreatment with the same anti-TNF drug was effective and safe

    El registro ENEIDA (Estudio Nacional en Enfermedad Inflamatoria intestinal sobre Determinantes genéticos y Ambientales) de GETECCU: diseño, monitorización y funciones

    Get PDF
    El registro ENEIDA, promovido por el Grupo Español de Trabajo en Enfermedad de Crohn y Colitis Ulcerosa (GETECCU), fue creado en 2005 por un grupo de gastroenterólogos interesados en mejorar el manejo de los pacientes con enfermedad inflamatoria intestinal. Los objetivos principales del registro fueron facilitar la recogida de datos clínicos de interés para la práctica clínica asistencial, así como la elaboración de estudios colaborativos a partir de datos clínicos y muestras biológicas. En sus 15 años de existencia, ENEIDA ha evolucionado en múltiples aspectos, desde su contenido o su soporte tecnológico hasta el número de centros participantes, para convertirse en uno de los registros de referencia para el estudio y cuidado de los pacientes con enfermedad inflamatoria intestinal, con una producción científica continua y de alta calidad que lo ha situado como ejemplo de explotación científica colaborativa en el ámbito internacional. En este artículo se revisan los objetivos, el diseño, las características estructurales, la monitorización y la explotación científica del registro ENEIDA

    Single hadron response measurement and calorimeter jet energy scale uncertainty with the ATLAS detector at the LHC

    Get PDF
    The uncertainty on the calorimeter energy response to jets of particles is derived for the ATLAS experiment at the Large Hadron Collider (LHC). First, the calorimeter response to single isolated charged hadrons is measured and compared to the Monte Carlo simulation using proton-proton collisions at centre-of-mass energies of sqrt(s) = 900 GeV and 7 TeV collected during 2009 and 2010. Then, using the decay of K_s and Lambda particles, the calorimeter response to specific types of particles (positively and negatively charged pions, protons, and anti-protons) is measured and compared to the Monte Carlo predictions. Finally, the jet energy scale uncertainty is determined by propagating the response uncertainty for single charged and neutral particles to jets. The response uncertainty is 2-5% for central isolated hadrons and 1-3% for the final calorimeter jet energy scale.Comment: 24 pages plus author list (36 pages total), 23 figures, 1 table, submitted to European Physical Journal

    Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

    Get PDF
    This paper presents measurements of the W+μ+νW^+ \rightarrow \mu^+\nu and WμνW^- \rightarrow \mu^-\nu cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13

    Measurement of χ c1 and χ c2 production with s√ = 7 TeV pp collisions at ATLAS

    Get PDF
    The prompt and non-prompt production cross-sections for the χ c1 and χ c2 charmonium states are measured in pp collisions at s√ = 7 TeV with the ATLAS detector at the LHC using 4.5 fb−1 of integrated luminosity. The χ c states are reconstructed through the radiative decay χ c → J/ψγ (with J/ψ → μ + μ −) where photons are reconstructed from γ → e + e − conversions. The production rate of the χ c2 state relative to the χ c1 state is measured for prompt and non-prompt χ c as a function of J/ψ transverse momentum. The prompt χ c cross-sections are combined with existing measurements of prompt J/ψ production to derive the fraction of prompt J/ψ produced in feed-down from χ c decays. The fractions of χ c1 and χ c2 produced in b-hadron decays are also measured
    corecore