6,250 research outputs found

    Dynamic simulations in SixTrack

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    The DYNK module allows element settings in SixTrack to be changed on a turn-by-turn basis. This document contains a technical description of the DYNK module in SixTrack. It is mainly intended for a developer or advanced user who wants to modify the DYNK module, for example by adding more functions that can be used to calculate new element settings, or to add support for new elements that can be used with DYNK.Comment: Submission to CERN yellow report / conference proceeding, the 2015 collimation tracking code worksho

    A Variational Sum-Rule Approach to Collective Excitations of a Trapped Bose-Einstein Condensate

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    It is found that combining an excitation-energy sum rule with Fetter's trial wave function gives almost exact low-lying collective-mode frequencies of a trapped Bose-Einstein condensate at zero temperature.Comment: 11 pages, 2 figures, Revte

    Scaling properties of protein family phylogenies

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    One of the classical questions in evolutionary biology is how evolutionary processes are coupled at the gene and species level. With this motivation, we compare the topological properties (mainly the depth scaling, as a characterization of balance) of a large set of protein phylogenies with a set of species phylogenies. The comparative analysis shows that both sets of phylogenies share remarkably similar scaling behavior, suggesting the universality of branching rules and of the evolutionary processes that drive biological diversification from gene to species level. In order to explain such generality, we propose a simple model which allows us to estimate the proportion of evolvability/robustness needed to approximate the scaling behavior observed in the phylogenies, highlighting the relevance of the robustness of a biological system (species or protein) in the scaling properties of the phylogenetic trees. Thus, the rules that govern the incapability of a biological system to diversify are equally relevant both at the gene and at the species level.Comment: Replaced with final published versio

    Opening the Window for Electroweak Baryogenesis

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    We perform an analysis of the behaviour of the electroweak phase transition in the Minimal Supersymmetric Standard Model, in the presence of light stops. We show that, in previously unexplored regions of parameter space, the order parameter v(Tc)/Tcv(T_c)/T_c can become significantly larger than one, for values of the Higgs and supersymmetric particle masses consistent with the present experimental bounds. This implies that baryon number can be efficiently generated at the electroweak phase transition. As a by-product of this study, we present an analysis of the problem of colour breaking minima at zero and finite temperature, and we use it to investigate the region of parameter space preferred by the best fit to the present precision electroweak measurement data, in which the left-handed stops are much heavier than the right-handed ones.Comment: 16 pages, LaTeX + 4 figures, psfig. (uuencoded

    Pure cervical radiculopathy due to spontaneous spinal epidural haematoma (SSEH): report of a case solved conservatively

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    Introduction: Spontaneous spinal epidural haematoma (SSEH) is widely recognised throughout the literature as a cause of myelopathy, radicular compression being very rarely reported. Surgical management is almost always recommended, especially in the cases of spinal cord compression. Conservative treatment is reported as a curiosity and only in the case of spontaneous improvement. This report presents the particular case of a 64-year-old patient undergoing anticoagulant therapy that had a cervical radiculopathy due to a SSEH confirmed by MRI. The patient improved spontaneously and symptoms were solved with unconventional conservative treatment and without stopping the anticoagulant therapy. Conclusions: Spontaneous epidural haematoma must be kept in mind when patients undergoing anticoagulant therapy have a sudden onset of cervicobrachialgia. Even though most spinal surgeons advocate surgical treatment, a conservative approach may lead to a complete recovery and may be considered as a good option in the case of radicular involvement. Discontinuation of the anticoagulant therapy may not always be needed, especially when the clinical syndrome improves spontaneously

    Collective Thomson scattering measurements of fast-ion transport due to sawtooth crashes in ASDEX Upgrade

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    Sawtooth instabilities can modify heating and current-drive profiles and potentially increase fast-ion losses. Understanding how sawteeth redistribute fast ions as a function of sawtooth parameters and of fast-ion energy and pitch is hence a subject of particular interest for future fusion devices. Here we present the first collective Thomson scattering (CTS) measurements of sawtooth-induced redistribution of fast ions at ASDEX Upgrade. These also represent the first localized fast-ion measurements on the high-field side of this device. The results indicate fast-ion losses in the phase-space measurement volume of about 50% across sawtooth crashes, in good agreement with values predicted with the Kadomtsev sawtooth model implemented in TRANSP and with the sawtooth model in the EBdyna_go code. In contrast to the case of sawteeth, we observe no fast-ion redistribution in the presence of fishbone modes. We highlight how CTS measurements can discriminate between different sawtooth models, in particular when aided by multi-diagnostic velocity-space tomography, and briefly discuss our results in light of existing measurements from other fast-ion diagnostics

    Forward Global Photometric Calibration of the Dark Energy Survey

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    Many scientific goals for the Dark Energy Survey (DES) require calibration of optical/NIR broadband b=grizYb = grizY photometry that is stable in time and uniform over the celestial sky to one percent or better. It is also necessary to limit to similar accuracy systematic uncertainty in the calibrated broadband magnitudes due to uncertainty in the spectrum of the source. Here we present a "Forward Global Calibration Method (FGCM)" for photometric calibration of the DES, and we present results of its application to the first three years of the survey (Y3A1). The FGCM combines data taken with auxiliary instrumentation at the observatory with data from the broad-band survey imaging itself and models of the instrument and atmosphere to estimate the spatial- and time-dependence of the passbands of individual DES survey exposures. "Standard" passbands are chosen that are typical of the passbands encountered during the survey. The passband of any individual observation is combined with an estimate of the source spectral shape to yield a magnitude mbstdm_b^{\mathrm{std}} in the standard system. This "chromatic correction" to the standard system is necessary to achieve sub-percent calibrations. The FGCM achieves reproducible and stable photometric calibration of standard magnitudes mbstdm_b^{\mathrm{std}} of stellar sources over the multi-year Y3A1 data sample with residual random calibration errors of σ=5−6 mmag\sigma=5-6\,\mathrm{mmag} per exposure. The accuracy of the calibration is uniform across the 5000 deg25000\,\mathrm{deg}^2 DES footprint to within σ=7 mmag\sigma=7\,\mathrm{mmag}. The systematic uncertainties of magnitudes in the standard system due to the spectra of sources are less than 5 mmag5\,\mathrm{mmag} for main sequence stars with 0.5<g−i<3.00.5<g-i<3.0.Comment: 25 pages, submitted to A

    Wnt signaling and Loxl2 promote aggressive osteosarcoma

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    Osteosarcoma (OS) is the most frequent primary malignant bone tumor in urgent need of better therapies. Using genetically modified mouse models (GEMMs), we demonstrate that Wnt signaling promotes c-Fos-induced OS formation via the actions of the collagen-modifying enzyme Loxl2. c-Fos/AP-1 directly regulates the expression of the Wnt ligands Wnt7b and Wnt9a in OS cells through promoter binding, and Wnt7b and Wnt9a in turn promote Loxl2 expression in murine and human OS cells through the transcription factors Zeb1 and Zeb2. Concordantly, inhibition of Wnt ligand secretion by inactivating the Wnt-less (Wls) gene in osteoblasts in c-Fos GEMMs either early or in a therapeutic setting reduces Loxl2 expression and progression of OS. Wls-deficient osteosarcomas proliferate less, are less mineralized and are enriched in fibroblastic cells surrounded by collagen fibers. Importantly, Loxl2 inhibition using either the pan-Lox inhibitor BAPN or a specific inducible shRNA reduces OS cell proliferation in vitro and decreases tumor growth and lung colonization in murine and human orthotopic OS transplantation models. Finally, OS development is delayed in c-Fos GEMMs treated with BAPN or with specific Loxl2 blocking antibodies. Congruently, a strong correlation between c-FOS, LOXL2 and WNT7B/WNT9A expression is observed in human OS samples, and c-FOS/LOXL2 coexpression correlates with OS aggressiveness and decreased patient survival. Therefore, therapeutic targeting of Wnt and/or Loxl2 should be considered to potentiate the inadequate current treatments for pediatric, recurrent, and metastatic OS

    Chemical Abundance Analysis of Tucana III, the Second rr-process Enhanced Ultra-Faint Dwarf Galaxy

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    We present a chemical abundance analysis of four additional confirmed member stars of Tucana III, a Milky Way satellite galaxy candidate in the process of being tidally disrupted as it is accreted by the Galaxy. Two of these stars are centrally located in the core of the galaxy while the other two stars are located in the eastern and western tidal tails. The four stars have chemical abundance patterns consistent with the one previously studied star in Tucana III: they are moderately enhanced in rr-process elements, i.e. they have ≈+ \approx +0.4 dex. The non-neutron-capture elements generally follow trends seen in other dwarf galaxies, including a metallicity range of 0.44 dex and the expected trend in α\alpha-elements, i.e., the lower metallicity stars have higher Ca and Ti abundance. Overall, the chemical abundance patterns of these stars suggest that Tucana III was an ultra-faint dwarf galaxy, and not a globular cluster, before being tidally disturbed. As is the case for the one other galaxy dominated by rr-process enhanced stars, Reticulum II, Tucana III's stellar chemical abundances are consistent with pollution from ejecta produced by a binary neutron star merger, although a different rr-process element or dilution gas mass is required to explain the abundances in these two galaxies if a neutron star merger is the sole source of rr-process enhancement.Comment: 18 pages, 10 figures; accepted by Ap
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