414 research outputs found

    Software Sustainability Assessment (SoSA) exercise report

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    This document reports on an exercise carried out within the CAiSE 2016 tutorial. The participants were asked to apply the SoSA method on a case, divided into three distinct groups. Then they were asked to provide feedback on the method. Herein, we analyse the results of their models, their feedback and we discuss benefits and drawbacks of the method

    Holography and Variable Cosmological Constant

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    An effective local quantum field theory with UV and IR cutoffs correlated in accordance with holographic entropy bounds is capable of rendering the cosmological constant (CC) stable against quantum corrections. By setting an IR cutoff to length scales relevant to cosmology, one easily obtains the currently observed rho_Lambda ~ 10^{-47} GeV^4, thus alleviating the CC problem. It is argued that scaling behavior of the CC in these scenarios implies an interaction of the CC with matter sector or a time-dependent gravitational constant, to accommodate the observational data.Comment: 7 pages, final version accepted by PR

    Evaluation of resistive-plate-chamber-based TOF-PET applied to in-beam particle therapy monitoring

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    Particle therapy is a highly conformal radiotherapy technique which reduces the dose deposited to the surrounding normal tissues. In order to fully exploit its advantages, treatment monitoring is necessary to minimize uncertainties related to the dose delivery. Up to now, the only clinically feasible technique for the monitoring of therapeutic irradiation with particle beams is Positron Emission Tomography (PET). In this work we have compared a Resistive Plate Chamber (RPC)-based PET scanner with a scintillation-crystal-based PET scanner for this application. In general, the main advantages of the RPC-PET system are its excellent timing resolution, low cost, and the possibility of building large area systems. We simulated a partial-ring scannerbeam monitoring, which has an intrinsically low positron yield compared to diagnostic PET. In addition, for in-beam PET there is a further data loss due to the partial ring configuration. In order to improve the performance of the RPC-based scanner, an improved version of the RPC detector (modifying the thickness of the gas and glass layers), providing a larger sensitivity, has been simulated and compared with an axially extended version of the crystal-based device. The improved version of the RPC shows better performance than the prototype, but the extended version of the crystal-based PET outperforms all other options. based on an RPC prototype under construction within the Fondazione per Adroterapia Oncologica (TERA). For comparison with the crystal-based PET scanner we have chosen the geometry of a commercially available PET scanner, the Philips Gemini TF. The coincidence time resolution used in the simulations takes into account the current achievable values as well as expected improvements of both technologies. Several scenarios (including patient data) have been simulated to evaluate the performance of different scanners. Initial results have shown that the low sensitivity of the RPC hampers its application to hadro

    M31's Heavy Element Distribution and Outer Disk

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    Hubble Space Telescope imaging of 11 fields in M31 were reduced to color-magnitude diagrams. The fields were chosen to sample all galactocentric radii to 50 kpc. Assuming that the bulk of the sampled stellar populations are older than a few Gyr, the colors of the red giants map to an abundance distribution with errors of order 0.1 dex in abundance. The radially sampled abundance distributions are all about the same width, but show a mild abundance gradient that flattens outside ~20 kpc. The various distributions were weighted and summed with the aid of new surface brightness profile fits to obtain an abundance distribution representative of the entirety of M31. M31 is a system near chemical maturity. This ``observed closed box'' is compared to analytical closed box models. M31 suffers from a lack of metal-poor stars and metal-rich stars relative to the simplest closed-box model in the same way as the solar neighborhood.Comparing to several simple chemical evolution models, neither complete mixing of gas at all times nor zero mixing, inhomogeneous models give the most convincing match to the data. As noted elsewhere, the outer disk of M31 is a factor of ten more metal-rich than the Milky Way halo, ten times more metal-rich than the dwarf spheroidals cospatial with it, and more metal-rich than most of the globular clusters at the same galactocentric radius. Difficulties of interpretation are greatly eased if we posit that the M31 disk dominates over the halo at all radii out to 50 kpc. In fact, scaling from current density models of the Milky Way, one should not expect to see halo stars dominating over disk stars until beyond our 50 kpc limit. A corollary conclusion is that most published studies of the M31 "halo" are actually studies of its disk.Comment: 28 pages, 11 black-and-white figures, in press, Astrophysical Journa

    Resummed Quantum Gravity

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    We present the current status of the a new approach to quantum general relativity based on the exact resummation of its perturbative series as that series was formulated by Feynman. We show that the resummed theory is UV finite and we present some phenomenological applications as well.Comment: 4 pages, 1 figure; presented at ICHEP0

    Onecut-dependent Nkx6.2 transcription factor expression is required for proper formation and activity of spinal locomotor circuits.

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    In the developing spinal cord, Onecut transcription factors control the diversification of motor neurons into distinct neuronal subsets by ensuring the maintenance of Isl1 expression during differentiation. However, other genes downstream of the Onecut proteins and involved in motor neuron diversification have remained unidentified. In the present study, we generated conditional mutant embryos carrying specific inactivation of Onecut genes in the developing motor neurons, performed RNA-sequencing to identify factors downstream of Onecut proteins in this neuron population, and employed additional transgenic mouse models to assess the role of one specific Onecut-downstream target, the transcription factor Nkx6.2. Nkx6.2 expression was up-regulated in Onecut-deficient motor neurons, but strongly downregulated in Onecut-deficient V2a interneurons, indicating an opposite regulation of Nkx6.2 by Onecut factors in distinct spinal neuron populations. Nkx6.2-null embryos, neonates and adult mice exhibited alterations of locomotor pattern and spinal locomotor network activity, likely resulting from defective survival of a subset of limb-innervating motor neurons and abnormal migration of V2a interneurons. Taken together, our results indicate that Nkx6.2 regulates the development of spinal neuronal populations and the formation of the spinal locomotor circuits downstream of the Onecut transcription factors

    Mass-Varying Neutrinos from a Variable Cosmological Constant

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    We consider, in a completely model-independent way, the transfer of energy between the components of the dark energy sector consisting of the cosmological constant (CC) and that of relic neutrinos. We show that such a cosmological setup may promote neutrinos to mass-varying particles, thus resembling a recently proposed scenario of Fardon, Nelson, and Weiner (FNW), but now without introducing any acceleronlike scalar fields. Although a formal similarity of the FNW scenario with the variable CC one can be easily established, one nevertheless finds different laws for neutrino mass variation in each scenario. We show that as long as the neutrino number density dilutes canonically, only a very slow variation of the neutrino mass is possible. For neutrino masses to vary significantly (as in the FNW scenario), a considerable deviation from the canonical dilution of the neutrino number density is also needed. We note that the present `coincidence' between the dark energy density and the neutrino energy density can be obtained in our scenario even for static neutrino masses.Comment: 8 pages, minor corrections, two references added, to apear in JCA

    Correlates of ideal cardiovascular health in European adolescents: The HELENA study

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    Background and aims: The ideal cardiovascular health (iCVH) construct consists of 4 health behaviors (smoking status, body mass index, physical activity and diet) and 3 health factors (total cholesterol, blood pressure and fasting glucose). A greater number of iCVH components in adolescence are related to better cardiovascular health, but little is known about the correlates of iCVH in adolescents. Thus, the aim of the study was to examine correlates of iCVH in European adolescents. Methods and results: The study comprised 637 European adolescents with complete iCVH data. Participants were part of the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) study, a cross-sectional, multicenter study conducted in 9 different European countries. Correlates investigated were sex and age, family affluence scale, maternal education, geographic location, sleep time, television viewing, duration of pregnancy, birth weight and breastfeeding. Younger adolescents, those whose mothers had medium/high education or those whowatched television less than 2 h per day had a greater number of iCVH components compared to those who were older, had a mother with low education or watched television 2 h or more daily (P <= 0.01). Conclusion: Since in our study older adolescents had worse iCVH than younger adolescents, early promotion of cardiovascular health may be important. Future studies mayalso investigate the usefulness of limiting television viewing to promote iCVH. Finally, since adolescents of mothers with low education had poorer iCVH, it may be of special interest to tailor public health promotion to adolescents from families with low socioeconomic status

    N-glycans of Human Protein C Inhibitor: Tissue-Specific Expression and Function

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    Protein C inhibitor (PCI) is a serpin type of serine protease inhibitor that is found in many tissues and fluids in human, including blood plasma, seminal plasma and urine. This inhibitor displays an unusually broad protease specificity compared with other serpins. Previous studies have shown that the N-glycan(s) and the NH2-terminus affect some blood-related functions of PCI. In this study, we have for the first time determined the N-glycan profile of seminal plasma PCI, by mass spectrometry. The N-glycan structures differed markedly compared with those of both blood-derived and urinary PCI, providing evidence that the N-glycans of PCI are expressed in a tissue-specific manner. The most abundant structure (m/z 2592.9) had a composition of Fuc3Hex5HexNAc4, consistent with a core fucosylated bi-antennary glycan with terminal Lewisx. A major serine protease in semen, prostate specific antigen (PSA), was used to evaluate the effects of N-glycans and the NH2-terminus on a PCI function related to the reproductive tract. Second-order rate constants for PSA inhibition by PCI were 4.3±0.2 and 4.1±0.5 M−1s−1 for the natural full-length PCI and a form lacking six amino acids at the NH2-terminus, respectively, whereas these constants were 4.8±0.1 and 29±7 M−1s−1 for the corresponding PNGase F-treated forms. The 7–8-fold higher rate constants obtained when both the N-glycans and the NH2-terminus had been removed suggest that these structures jointly affect the rate of PSA inhibition, presumably by together hindering conformational changes of PCI required to bind to the catalytic pocket of PSA
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