12,814 research outputs found

    Photoproduction of mixed radions at a proton-proton collider

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    We investigate Higgs-radion mixing scenario through single radion photoproduction process pppγppRqXpp\to p\gamma p\to pRqX at the LHC where XX represents the remnants of one of the initial protons. We consider high luminosity values of Lint=200  fb1L_{int}=200\;fb^{-1}, 500  fb1500\;fb^{-1} and 3000  fb13000\;fb^{-1}. We obtain bounds on the mixing parameter space by considering RγγR\to \gamma\gamma, RW+WR\to W^+ W^- and RZZR\to ZZ decay channels of the radion as the signal. We also perform a similar analysis for a 100 TeV future proton-proton collider and compare its potential with that of LHC.Comment: 25 pages, 13 figure

    HD 179821 (V1427 Aql, IRAS 19114+0002) -- A Massive Post-Red Supergiant Star?

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    We have derived elemental abundances of a remarkable star, HD 179821, with unusual composition (e.g. [Na/Fe]=1.0±\pm0.2 dex) and extra-ordinary spectral characteristics. Its metallicity at [Fe/H]=0.4 dex places it among the most metal-rich stars yet analyzed. The abundance analysis of this luminous star is based on high resolution and high quality (S/N\approx120--420) optical echelle spectra from McDonald Observatory and Special Astronomy Observatory. The data includes five years of observations over twenty-one epochs. Standard 1D {\sc LTE} analysis provides a fresh determination of the atmospheric parameters over all epochs: \Teff = 7350±\pm200 \kelvin, \logg = +0.6±\pm0.3, and a microturbulent velocity ξ=\xi = 6.6±\pm1.6 km s1^{\rm -1} and [Fe/H] = 0.4±\pm0.2, and a carbon abundance [C/Fe]= -0.19±\pm0.30. We find oxygen abundance [O/Fe]= -0.25±\pm0.28 and an enhancement of 0.9 dex in N. A supersonic macroturbulent velocity of 22.0 ±\pm 2.0 km s1^{\rm -1} is determined from both strong and weak Fe\,{\sc i} and Fe\,{\sc ii} lines. Elemental abundances are obtained for 22 elements. HD 179821 is not enriched in s-process products. Eu is overabundant relative to the anticipated [X/Fe] \approx 0.0. Some peculiarities of its optical spectrum (e.g. variability in the spectral line shapes) is noticed. This includes the line profile variations for Hα\alpha line. Based on its estimated luminosity, effective temperature and surface gravity, HD 179821 is a massive star evolving to become a red supergiant and finally a Type II supernova.Comment: 19 pages, 8 figures, accepted for publication in MNRA

    Contracts, Biases and Consumption of Access Services

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    We consider a consumption model that takes into account the valuation and demand uncertainties that consumers face while using access services. Typical examples of such services include telecommunication services, extended warranties for consumer electronics, and club memberships. We demonstrate that consumption is affected by contract structure (pay-peruse vs. three part tariffs) even if the optimal consumption plans are identical. We find that a majority of individuals correctly use a threshold policy that is similar to a nearly optimal heuristic, however they use the free units too quickly leading to overconsumption and lost surplus. These errors are partially driven by mistaken beliefs about the value distribution. We also measure subjectsâ willingness to pay for a contract with free access units, and we find that nearly half of subjects are willing to pay at least the full per-unit price, with a substantial fraction willing to overpay. The optimal firm strategy is therefore to offer a contract that presells access units at a very small discount; this strategy increases revenue by 8 − 15% compared to only offering a pay-per-use contract.access services, pricing contracts, decision biases, experiment

    The labor market in the Great Recession: an update

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    Since the end of the Great Recession in mid-2009, the unemployment rate has recovered slowly, falling by only one percentage point from its peak. We find that the lackluster labor market recovery can be traced in large part to weakness in aggregate demand; only a small part seems attributable to increases in labor market frictions. This continued labor market weakness has led to the highest level of long-term unemployment in the U.S. in the postwar period, and a blurring of the distinction between unemployment and nonparticipation. We show that flows from nonparticipation to unemployment are important for understanding the recent evolution of the duration distribution of unemployment. Simulations that account for these flows suggest that the U.S. labor market is unlikely to be subject to high levels of structural long-term unemployment after aggregate demand recovers. ; Powerpoint supplement available at http://www.frbsf.org/economics/economists/wp11-29bk_supplement.pdfLabor market ; Recessions

    The effect of vascular graft and human umbilical cord blood-derived CD34+ stem cell on peripheral nerve healing

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    AIM: There are many trials concerning peripheral nerve damage causes and treatment options. Unfortunately, nerve damage is still a major problem regarding health, social and economic issues. On this study, we used vascular graft and human cord blood derived stem cells to find an alternative treatment solution to this problem. MATERIAL AND METHODS: We used 21 female Wistar rats on our study. They were anesthetized with ketamine and we studied right hind limbs. On Group 1, we did a full layer cut on the right sciatic nerve. On Group 2, we did a full layer cut on the right sciatic nerve, and we covered synthetic vascular graft on cut area. On Group 3, we did a full layer cut on right sciatic nerve, and we covered the area with stem cell applied vascular graft. RESULTS: At the end of postoperative 8. weeks, we performed EMG on the rats. When we compared healthy and degenerated areas as a result of EMG, we found significant amplitude differences between the groups on healthy areas whereas there was no significant difference on degenerated areas between the groups. Then we re-opened the operated area again to reveal the sciatic nerve cut area, and we performed electron microscope evaluation. On the stem cell group, we observed that both the axon and the myelin sheet prevented degeneration. CONCLUSION: This study is a first on using synthetic vascular graft and cord blood derived CD34+ cells in peripheral nerve degeneration. On the tissues that were examined with electron microscope, we observed that CD34+ cells prevented both axonal and myelin sheath degeneration. Nerve tissue showed similar results to the control group, and the damage was minimal. © 2018 Ali Yilmaz, Abdullah Topcu, Cagdas Erdogan, Levent Sinan Bir, Barbaros Sahin, Gulcin Abban, Erdal Coskun, Ayca Ozkul

    Contracts, biases and consumption of access services

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    We consider a consumption model that takes into account the valuation and demand uncertainties that consumers face while using access services. Typical examples of such services include telecommunication services, extended warranties for consumer electronics, and club memberships. We demonstrate that consumption is affected by contract structure (pay-peruse vs. three part tariffs) even if the optimal consumption plans are identical. We find that a majority of individuals correctly use a threshold policy that is similar to a nearly optimal heuristic, however they use the free units too quickly leading to overconsumption and lost surplus. These errors are partially driven by mistaken beliefs about the value distribution. We also measure subjects' willingness to pay for a contract with free access units, and we find that nearly half of subjects are willing to pay at least the full per-unit price, with a substantial fraction willing to overpay. The optimal firm strategy is therefore to offer a contract that presells access units at a very small discount; this strategy increases revenue by 8 - 15% compared to only offering a pay-per-use contract

    Ionic Capillary Evaporation in Weakly Charged Nanopores

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    Using a variational field theory, we show that an electrolyte confined to a neutral cylindrical nanopore traversing a low dielectric membrane exhibits a first-order ionic liquid-vapor pseudo-phase-transition from an ionic-penetration "liquid" phase to an ionic-exclusion "vapor" phase, controlled by nanopore-modified ionic correlations and dielectric repulsion. For weakly charged nanopores, this pseudotransition survives and may shed light on the mechanism behind the rapid switching of nanopore conductivity observed in experiments.Comment: This version is accepted for publication in PR
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