2,104 research outputs found

    Four-Quark Hadrons: an Updated Review

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    The past decade witnessed a remarkable proliferation of exotic charmonium-like resonances discovered at accelerators. In particular, the recently observed charged states are clearly not interpretable as q-qbar mesons. Notwithstanding the considerable advances on the experimental side, conflicting theoretical descriptions do not seem to provide a definitive picture about the nature of the so-called XYZ particles. We present here a comprehensive review about this intriguing topic, discussing both those experimental and theoretical aspects which we consider relevant to make further progress in the field. At this state of progress, XYZ phenomenology speaks in favour of the existence of compact four-quark particles (tetraquarks) and we believe that realizing this instructs us in the quest for a firm theoretical framework.Comment: 120 pages, 53 figures. Several typos corrected and some refs. added in v

    SWIPE: a bolometric polarimeter for the Large-Scale Polarization Explorer

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    The balloon-borne LSPE mission is optimized to measure the linear polarization of the Cosmic Microwave Background at large angular scales. The Short Wavelength Instrument for the Polarization Explorer (SWIPE) is composed of 3 arrays of multi-mode bolometers cooled at 0.3K, with optical components and filters cryogenically cooled below 4K to reduce the background on the detectors. Polarimetry is achieved by means of large rotating half-wave plates and wire-grid polarizers in front of the arrays. The polarization modulator is the first component of the optical chain, reducing significantly the effect of instrumental polarization. In SWIPE we trade angular resolution for sensitivity. The diameter of the entrance pupil of the refractive telescope is 45 cm, while the field optics is optimized to collect tens of modes for each detector, thus boosting the absorbed power. This approach results in a FWHM resolution of 1.8, 1.5, 1.2 degrees at 95, 145, 245 GHz respectively. The expected performance of the three channels is limited by photon noise, resulting in a final sensitivity around 0.1-0.2 uK per beam, for a 13 days survey covering 25% of the sky.Comment: In press. Copyright 2012 Society of Photo-Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibite

    Investigation of the effects of vitamin D and calcium on intestinal motility: In vitro tests and implications for clinical treatment

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    The presence of vitamin D receptors in small intestine muscle cells may lead one to think that vitamin D may act locally, influencing intracellular calcium concentration and contributing to the contraction-relaxation regulation of the intestinal smooth muscle cells. This study investigates the potential effects of vitamin D and calcium on intestinal motility using an in vitro test. Different calcium concentrations added to the tissue not pre-treated with 1,25-dihydroxycholecalciferol [1α,25(OH)2D3] produced no response at low doses (1.25×10–3 and 2.0×10–3 mol L–1) and only a very weak response at higher concentration (3.0×10–3 mol L–1). The addition of 1α,25(OH)2D3 (1.44×10–10 mol L–1) had no effect on isolated ileum motility. When calcium (3.0×10–3 mol L–1) was added after at least 3 hours, it evoked evident and persistent contractions for 60-90 minutes. The contractions were at about 40 % of the peak produced by acetylcholine.Thus, simultaneous intake of vitamin D and calcium might be a useful co-adjuvant in intestinal atony therapy aimed to stimulate normal gut motility in humans. These findings imply that supplemental vitamin D may be important in all cases where calcium has to be prescribed

    The Large-Scale Polarization Explorer (LSPE)

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    The LSPE is a balloon-borne mission aimed at measuring the polarization of the Cosmic Microwave Background (CMB) at large angular scales, and in particular to constrain the curl component of CMB polarization (B-modes) produced by tensor perturbations generated during cosmic inflation, in the very early universe. Its primary target is to improve the limit on the ratio of tensor to scalar perturbations amplitudes down to r = 0.03, at 99.7% confidence. A second target is to produce wide maps of foreground polarization generated in our Galaxy by synchrotron emission and interstellar dust emission. These will be important to map Galactic magnetic fields and to study the properties of ionized gas and of diffuse interstellar dust in our Galaxy. The mission is optimized for large angular scales, with coarse angular resolution (around 1.5 degrees FWHM), and wide sky coverage (25% of the sky). The payload will fly in a circumpolar long duration balloon mission during the polar night. Using the Earth as a giant solar shield, the instrument will spin in azimuth, observing a large fraction of the northern sky. The payload will host two instruments. An array of coherent polarimeters using cryogenic HEMT amplifiers will survey the sky at 43 and 90 GHz. An array of bolometric polarimeters, using large throughput multi-mode bolometers and rotating Half Wave Plates (HWP), will survey the same sky region in three bands at 95, 145 and 245 GHz. The wide frequency coverage will allow optimal control of the polarized foregrounds, with comparable angular resolution at all frequencies.Comment: In press. Copyright 2012 Society of Photo-Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibite

    Interleukin-9 Overexpression and Th9 Polarization Characterize the Inflamed Gut, the Synovial Tissue, and the Peripheral Blood of Patients With Psoriatic Arthritis

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    Objective. To investigate the expression and tis- sue distribution of Th9-related cytokines in patients with psoriatic arthritis (PsA). Methods. Quantitative gene expression analysis of Th1, Th17, and Th9 cytokines was performed in intestinal biopsy samples obtained from patients with PsA, HLA2B272positive patients with ankylosing spondylitis (AS), patients with Crohn’s disease (CD), and healthy controls. Expression and tissue distribu- tion of interleukin-23 (IL-23), IL-17, IL-22, IL-9, and IL-9 receptor (IL-9R) were evaluated by immunohisto- chemistry and confocal microscopy. Flow cytometry was used to study the frequency of Th9 cells among periph- eral blood, lamina propria, and synovial fluid mononuclear cells. The functional relevance of IL-9R expression on epithelial cells was assessed in functional in vitro studies. Th9 cells in synovial tissue from patients with PsA were also studied. Results. Subclinical gut inflammation in PsA patients was characterized by a clear Th17 and Th22, but not Th1, polarized immune response. Unlike AS and CD, a strong and significant up-regulation of IL-9 was observed in PsA gut, especially among infiltrating mononuclear cells, high endothelial venules, and Pan- eth cells. IL-92positive mononuclear cells were demon- strated to be in large part Th9 cells. IL-9 overexpression was accompanied by significant Paneth cell hyperplasia. Paneth cells strongly overexpressed IL-9R, and stimula- tion of epithelial cells, isolated from PsA patients, with IL-9 resulted in overexpression of a-defensin 5 and IL-23p19. Peripheral and synovial expansion of a4b71 Th9 cells was also observed in patients with PsA. Increased expression of IL-9 and IL-9R was also found in synovial tissue. Conclusion. Strong IL-9/Th9 polarization seems to be the predominant immunologic signature in patients in PsA

    Binary black hole merger in the extreme mass ratio limit

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    We discuss the transition from quasi-circular inspiral to plunge of a system of two nonrotating black holes of masses m1m_1 and m2m_2 in the extreme mass ratio limit m1m2≪(m1+m2)2m_1m_2\ll (m_1+m_2)^2. In the spirit of the Effective One Body (EOB) approach to the general relativistic dynamics of binary systems, the dynamics of the two black hole system is represented in terms of an effective particle of mass μ≡m1m2/(m1+m2)\mu\equiv m_1m_2/(m_1+m_2) moving in a (quasi-)Schwarzschild background of mass M≡m1+m2M\equiv m_1+m_2 and submitted to an O(μ){\cal O}(\mu) radiation reaction force defined by Pad\'e resumming high-order Post-Newtonian results. We then complete this approach by numerically computing, \`a la Regge-Wheeler-Zerilli, the gravitational radiation emitted by such a particle. Several tests of the numerical procedure are presented. We focus on gravitational waveforms and the related energy and angular momentum losses. We view this work as a contribution to the matching between analytical and numerical methods within an EOB-type framework.Comment: 14 pages, six figures. Revised version. To appear in the CQG special issue based around New Frontiers in Numerical Relativity conference, Golm (Germany), July 17-21 200
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