2,339 research outputs found

    Initial results from the HARP experiment at CERN

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    Initial results on particle yields obtained by the HARP experiment are presented. The measurements correspond to proton--nucleus collisions at beam energies of 12.9 GeV/cGeV/c and for a thin Al target of 5% interacion legth. The angular range considered is between 10 and 250 mradmrad. This results are the first step in the upcoming measurement of the forward production cross-section for the same target and beam energy, relevant for the calculation of the far--to--near ratio of the K2K experiment.Comment: Presented at the Neutrino 2004 Internation Conferenc

    The NEXT experiment

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    NEXT (Neutrino Experiment with a Xenon TPC) is an experiment to search neutrinoless double beta decay processes (ßß0¿ßß0¿). The isotope chosen by NEXT is 136Xe. The NEXT technology is based in the use of time projection chambers operating at a typical pressure of 15 bar and using electroluminescence to amplify the signal (HPXe). The main advantages of the experimental technique are: a) excellent energy resolution; b) the ability to reconstruct the trajectory of the two electrons emitted in the decays, a unique feature of the HPXe which further contributes to the suppression of backgrounds; c) scalability to large masses; and d) the possibility to reduce the background to negligible levels thanks to the barium tagging technology (BaTa). The NEXT roadmap was designed in four stages: i) Demonstration of the HPXe technology with prototypes deploying a mass of natural xenon in the range of 1 kg; ii) Characterisation of the backgrounds to the ßß0¿ßß0¿ signal and measurement of the ßß2¿ßß2¿ signal with the NEW detector, deploying 10 kg of enriched xenon and operating at the LSC; iii) Search for ßß0¿ßß0¿ decays with the NEXT-100 detector, which deploys 100 kg of enriched xenon; iv) Search for ßß0¿ßß0¿ decays with the BEXT detector, which will deploy masses in the range of the ton and will introduce two additional handles, only possible in a HPXe: a) A magnetic field, capable of further enhancing the topological signal of NEXT; and b) barium-tagging (a technique pioneered by the EXO experiment which is also accessible to NEXT). The first stage of NEXT has been successfully completed during the period 2009–2013. The prototypes NEXT-DEMO (IFIC) and NEXT-DBDM (Berkeley) were built and operated for more than two years. These apparatuses have demonstrated the main features of the technology. The experiment is currently developing its second phase. The NEW detector is being constructed during 2014 and will operate in the LSC during 2015. The NEXT-100 detector will be built and commissioned during 2016 and 2017 and will start data taking in 2018. NEXT-100 could discover ßß0¿ßß0¿ processes if the period of the decay is equal or less than 6×10256×1025 year. The fourth phase of the experiment (BEXT) could start in 2020

    A new player in cartilage homeostasis: adiponectin induces nitric oxide synthase type II and pro-inflammatory cytokines in chondrocytes

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    SummaryObjectiveRecent studies revealed a close connection between adipose tissue, adipokines and articular degenerative inflammatory diseases such as rheumatoid arthritis (RA) and osteoarthritis (OA). The goal of this work was to investigate the activity of adiponectin in human and murine chondrocytes and to study its functional role in the modulation of nitric oxide synthase type II (NOS2). For completeness, interleukin (IL)-6, IL-1β, matrix metalloproteinase (MMP)-2, MMP-3, MMP-9, tissue inhibitor of metalloproteinase (TIMP)-1, prostaglandin E2 (PGE2), leukotriene B4 (LTB4), tumor necrosis factor alpha (TNF)-α and monocyte chemoattractant protein-1 (MCP-1) accumulation have been evaluated in adiponectin-stimulated chondrocytes cell culture supernatants.MethodsMurine ATDC5 cell line, C28/I2, C20A4, TC28a2 human immortalized chondrocytes, and human cultured chondrocytes were used. Nitrite accumulation was determined by Griess reaction. Adiponectin receptors (AdipoRs) expression was evaluated by immunofluorescence microscopy and confirmed by reverse transcriptase-polymerase chain reaction. NOS2 expression was evaluated by Western blot analysis whereas cytokines, prostanoids and metalloproteinases production was evaluated by specific enzyme-linked immunosorbent assays.ResultsHuman and murine chondrocytes express functional AdipoRs. Adiponectin induces NOS2. This effect is inhibited by aminoguanidine, dexamethasone and by a selective inhibitor of phosphatidylinositol 3-kinase. In addition, adiponectin is able to increase IL-6, MMP-3, MMP-9 and MCP-1 by murine cultured chondrocytes whereas it was unable to modulate TNF-α, IL-1β, MMP-2, TIMP-1, PGE2 and LTB4 release.ConclusionsThese results bind more closely the interactions between fat-derived adipokines and articular inflammatory diseases, and suggest that adiponectin is a novel key element in the maintenance of cartilage homeostasis which might be considered as a potential therapeutical target in joint degenerative diseases

    Novel Microscopic Mechanism of Intermixing during Growth on Soft Metallic Substrates

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    Generic computer simulations using empiric interatomic potentials suggest a new, collective mechanism that could be responsible for mixing at heteroepitaxial interfaces. Even if single adsorbate atoms diffuse by hopping on the substrate surface and do not mix at the terraces, two-dimensional islands formed by nucleation may become unstable above a certain critical size and explode upwards forming clusters of several atomic layers. This process is accompanied by strong distortions of the underlying atomic layers, and on soft materials it can result in surface etching and incorporation of substrate atoms into the islands.Fil: Gomez, Liliana Maria. Universidad Nacional de Rosario. Facultad de Ciencias Exactas, Ingeniería y Agrimensura; ArgentinaFil: Slutzky, Claudia Marcela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Ferron, Julio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: de la Figuera, J.. Sandia National Laboratories; Estados UnidosFil: Camarero, J.. Universidad Autónoma de Madrid; EspañaFil: Vazquez de Parga, A.. Universidad Autónoma de Madrid; EspañaFil: de Miguel, J.J.. Universidad Autónoma de Madrid; EspañaFil: Miranda, R.. Universidad Autónoma de Madrid; Españ

    Markers of inflammation and bone remodelling associated with improvement in clinical response measures in psoriatic arthritis patients treated with golimumab

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    <p>Objective To determine serum biomarker associations with clinical response to golimumab treatment in patients with psoriatic arthritis (PsA).</p> <p>Methods GO–REVEAL was a randomised, placebo-controlled study of golimumab in patients with active PsA. Samples were collected from 100 patients at baseline, week 4 and week 14, and analysed for serum-based biomarkers and protein profiling (total 92 markers); data were correlated with clinical measures at week 14.</p> <p>Results Serum levels of a subset of proteins (apolipoprotein C III, ENRAGE, IL-16, myeloperoxidase, vascular endothelial growth factor, pyridinoline, matrix metalloproteinase 3, C-reactive protein (CRP), carcinoembryonic antigen, intercellular adhesion molecule 1 and macrophage inflammatory protein 1α) at baseline or week 4 were strongly associated with American College of Rheumatology 20% improvement (ACR20) response and/or disease activity score in 28 joints (DAS28) at week 14. A smaller subset of proteins was significantly associated with a 75% improvement in the psoriasis area and severity index score (PASI75) at week 14, (adiponectin, apolipoprotein CIII, serum glutamic oxaloacetic transaminase, and tumour necrosis factor α). Subsets of proteins were identified as potentially predictive of clinical response for each of the clinical measures, and the power of these biomarker panels to predict clinical response to golimumab treatment was stronger than for CRP alone.</p> <p>Conclusions This analysis provides insight into several panels of markers that may have utility in identifying PsA patients likely to have ACR20, DAS28, or PASI75 responses following golimumab treatment.</p&gt

    On supersymmetric Minkowski vacua in IIB orientifolds

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    Supersymmetric Minkowski vacua in IIB orientifold compactifications based on orbifolds with background fluxes and non-perturbative superpotentials are investigated. Especially, microscopic requirements and difficulties to obtain such vacua are discussed. We show that orbifold models with one and two complex structure moduli and supersymmetric 2-form flux can be successfully stabilized to such vacua. By taking additional gaugino condensation on fixed space-time filling D3-branes into account also models without complex structure can be consistently stabilized to Minkowski vacua.Comment: 17 pages, 2 figures; More detailed proof for absence of complex flat directions in susy AdS vacua given; Footnotes and reference adde

    SQUID-based microtesla MRI for in vivo relaxometry of the human brain

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    SQUID-based MRI (magnetic resonance imaging) at microtesla fields has developed significantly over the past few years. Here we describe application of this method for magnetic relaxation measurements in the living human brain. We report values of the longitudinal relaxation time T1 for brain tissues, measured in vivo for the first time at microtesla fields. The experiments were performed at 46 microtesla field using a seven-channel SQUID system designed for microtesla MRI and MEG. Values of T1, measured for different tissues at this field, are found to be close (within 5%) to the corresponding values of the transverse relaxation time T2 at the same field. Implications of this result for imaging contrast in microtesla MRI are discussed.Comment: To appear in Proceedings of 2008 Applied Superconductivity Conferenc

    Large-x Parton Distributions

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    Reliable knowledge of parton distributions at large x is crucial for many searches for new physics signals in the next generation of collider experiments. Although these are generally well determined in the small and medium x range, it has been shown that their uncertainty grows rapidly for x>0.1. We examine the status of the gluon and quark distributions in light of new questions that have been raised in the past two years about "large-x" parton distributions, as well as recent measurements which have improved the parton uncertainties. Finally, we provide a status report of the data used in the global analysis, and note some of the open issues where future experiments, including those planned for Jefferson Labs, might contribute.Comment: LaTeX, 9 pages, 7 figures. Invited talk presented at the ``Workshop on Nucleon Structure in the High x-Bjorken Region (HiX2000),'' Temple University, Philadelphia, Pennsylvania, March 30-April 1, 200

    Neotectonics and current hydrologically-induced karst deformation. Case study of the Plateau de Carlern (Alpes-Maritimes, France)

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    International audienceThe astronomical and geodetic observatory OCA, located on the karst plateau of Calern (Caussols, France), has been monitoring earth deformation for several years. Two long baseline tiltmeters have been installed in a shaft in 2007, along with classical hydrogeological monitoring tools in order to investigate the relationship between current karst deformation and hydrology. Dye tests have shown that the plateau is drained towards the East, to the spring of Bramafam, except for its Western third. Karst tilting, as recorded by the tiltmeters, is linked to rainfall events. These instruments bring additional information to characterize different reservoirs: the deep karst aquifer of Bramafan with high amplitude oscillations of its water table, up to 100 m, the perched aquifer of Moustiques shaft whose response is attenuated, and several slope aquifers with reduced oscillations (Fontaniers, Castel Bon Pré). Tilt deformation reaches 8 μrad with a definite orientation between N90°E and N100°E. The best correlation between hydrology and tilts is observed for the deep aquifers. If the first autumn rainfall is ineffective on tilt, it recharges the epikarst and refills the reserves. The winter rains cause the water to flush towards the eastern deep aquifer and provokes a quick tilting of the plateau. Finally, the long term variations in tilt and water table show a very good correlation The relationship between current hydrological deformations and tectonics is also analyzed; broken and shifted speleothems in the shafts indicate a general shift of the plateau towards the south

    Inflation with racetrack superpotential and matter field

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    Several models of inflation with the racetrack superpotential for the volume modulus coupled to a matter field are investigated. In particular, it is shown that two classes of racetrack inflation models, saddle point and inflection point ones, can be constructed in a fully supersymmetric framework with the matter field F-term as a source of supersymmetry breaking and uplifting. Two models of F-term supersymmetry breaking are considered: the Polonyi model and the quantum corrected O'Raifeartaigh model. In the former case, both classes of racetrack inflation models differ significantly from the corresponding models with non-supersymmetric uplifting. The main difference is a quite strong dominance of the inflaton by the matter field. In addition, fine-tuning of the parameters is relaxed as compared to the original racetrack models. In the case of the racetrack inflation models coupled to the O'Raifeartaigh model, the matter field is approximately decoupled from the inflationary dynamics. In all of the above models the gravitino mass is larger than the Hubble scale during inflation. The possibility of having the gravitino much lighter than the Hubble scale is also investigated. It is very hard to construct models with light gravitino in which the volume modulus dominates inflation. On the other hand, models in which the inflationary dynamics is dominated by the matter field are relatively simple and seem to be more natural.Comment: 40 pages, 13 figures, references added, typos corrected, version to be publishe
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