1,634 research outputs found

    Top quark spin in ep collision

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    We discuss the degree of spin polarization of single top quarks produced via WgWg fusion process in epep collision at TESLA+HERAp and CLIC+LHC energies s=1.6\sqrt{s}=1.6 and 5.3 TeV. A description on how to combine the cross sections of e+btνˉe^{+}b\to t\bar{\nu} and e+gtbˉνˉe^{+}g\to t\bar{b}\bar{\nu} processes is given. e+e^{+}-beam direction is taken to be the favorite top quark spin decomposition axis in its rest frame and it is found to be comparable with the ones in pppp collision. It is argued that theoretical simplicity and experimental clearness are the advantage of epep collision.Comment: 2 eps figure

    Graphene coatings: An efficient protection from oxidation

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    We demonstrate that graphene coating can provide an efficient protection from oxidation by posing a high energy barrier to the path of oxygen atom, which could have penetrated from the top of graphene to the reactive surface underneath. Graphene bilayer, which blocks the diffusion of oxygen with a relatively higher energy barrier provides even better protection from oxidation. While an oxygen molecule is weakly bound to bare graphene surface and hence becomes rather inactive, it can easily dissociates into two oxygen atoms adsorbed to low coordinated carbon atoms at the edges of a vacancy. For these oxygen atoms the oxidation barrier is reduced and hence the protection from oxidation provided by graphene coatings is weakened. Our predictions obtained from the state of the art first-principles calculations of electronic structure, phonon density of states and reaction path will unravel how a graphene can be used as a corrosion resistant coating and guide further studies aiming at developing more efficient nanocoatings.Comment: under review in PRB; http://link.aps.org/doi/10.1103/PhysRevB.85.15544

    Even Kakutani Equivalence And The Loose Block Independence Property For Positive Entropy Zᵈ Actions

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    In this paper we define the loose block independence property for positive entropy Zᵈ actions and extend some of the classical results to higher dimensions. In particular, we prove that two loose block independent actions are even Kakutani equivalent if and only if they have the same entropy. We also prove that for d \u3e 1 the ergodic, isometric extensions of the positive entropy loose block independent Zᵈ actions are also loose block independent

    The association between the prevalence of restless leg syndrome, fatigue, and sleep quality in patients undergoing hemodialysis

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    Objective: To determine the prevalence of restless legs syndrome (RLS) in patients with chronic renal failure (CRF) and to compare CRF patients with or without RLS in terms fatigue and sleep quality. Methods: A cross-sectional study was conducted on 220 patients (18-75 years) who were undergoing dialysis 3 times weekly in Çorum Province, Corum, Turkey, between January 2014 and January 2016. The diagnosis of RLS was based on the diagnostic form proposed by the international RLS study group. Sleep quality was evaluated using the Pittsburgh sleep quality index (PSQI), and severity of fatigue was determined by using fatigue severity scale (FSS). Results: Of all the participants, 16.8% (n= 37) (Group 1) were found to have RLS, while 183 patients had no RLS (Group 2). The mean ages were similar between groups. With respect to laboratory analyses, a p-value of <0.05 was considered in Group 1 than in Group 2. Restless legs syndrome was mild (7.1%), moderate (46.4%) and severe (39.3%) in patients with RLS. Factors associated with the severity of RLS included weight, duration of dialysis, anuria, iron, total iron binding capacity, calcium and transferrin saturation. The PSQI and FSS scores were significantly worse in Group 1 (p<0.001). Conclusion: Restless legs syndrome is a common condition in patients undergoing hemodialysis; the results of our study confirm the adverse effects of RLS in terms of many aspects of sleep quality and fatigue. © 2018, Saudi Arabian Armed Forces Hospital. All rights reserved

    An Iterative Cyclic Algorithm for Designing Vaccine Distribution Networks in Low and Middle-Income Countries

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    The World Health Organization's Expanded Programme on Immunization (WHO-EPI) was developed to ensure that all children have access to common childhood vaccinations. Unfortunately, because of inefficient distribution networks and cost constraints, millions of children in many low and middle-income countries still go without being vaccinated. In this paper, we formulate a mathematical programming model for the design of a typical WHO-EPI network with the goal of minimizing costs while providing the opportunity for universal coverage. Since it is only possible to solve small versions of the model optimally, we describe an iterative heuristic that cycles between solving restrictions of the original problem and show that it can find very good solutions in reasonable time for larger problems that are not directly solvable.Comment: International Joint Conference on Industrial Engineering and Operations Management- ABEPRO-ADINGOR-IISE-AIM-ASEM (IJCIEOM 2019). Novi Sad, Serbia, July 15-17t

    Estimation of Purcell factor from mode-splitting spectra in an optical microcavity

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    We investigate scattering process in an ultra-high-Q optical microcavity coupled to subwavelength scatterers by introducing "splitting quality" Qsp, a dimensionless parameter defined as the ratio of the scatterer-induced mode splitting to the total loss of the coupled system. A simple relation is introduced to directly estimate the Purcell factor from single-shot measurement of transmission spectrum of scatterer-coupled cavity. Experiments with polystyrene (PS) and gold (Au) nanoparticles, Erbium ions and Influenza A virions show that Purcell-factor-enhanced preferential funneling of scattering into the cavity mode takes place regardless of the scatterer type. Experimentally determined highest Qsp for single PS and Au nanoparticles are 9.4 and 16.19 corresponding to Purcell factors with lower bounds of 353 and 1049, respectively. The highest observed Qsp was 31.2 for an ensemble of Au particles. These values are the highest Qsp and Purcell factors reported up to date.Comment: 5 Pages, 4 Figures, 12 Reference

    Unparticle Physics in the Moller Scattering

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    We investigate the virtual effects of vector unparticles in the Moller scattering. We derive the analytic expression for scattering amplitudes with unpolarized beams. We obtain 95% confidence level limits on the unparticle couplings λV\lambda_{V} and λA\lambda_{A} with integrated luminosity of Lint=50,500fb1L_{int}=50, 500 fb^{-1} and s=100,300\sqrt{s}=100, 300 and 500 GeV energies. We show that limits on λV\lambda_{V} are more sensitive than λA\lambda_{A}.Comment: 10 pages, 5 figures, 4 table

    Anomalous Quartic WWγγWW\gamma\gamma and ZZγγZZ\gamma\gamma Couplings in eγe\gamma Collision With Initial Beams and Final State Polarizations

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    The constraints on the anomalous quartic WWγγWW\gamma\gamma and ZZγγZZ\gamma\gamma gauge boson couplings are investigated through the processes eγWγνee\gamma\to W^{-}\gamma\nu_{e} and eγZγee\gamma\to Z\gamma e. Considering the longitudinal and transverse polarization states of the final W or Z boson and incoming beam polarizations we find 95% confidence level limits on the anomalous coupling parameters a0a_{0} and aca_{c} with an integrated luminosity of 500 fb1fb^{-1} and s\sqrt{s}=0.5, 1 TeV energies. Assuming the W+WγγW^{+}W^{-}\gamma\gamma couplings are independent of the ZZγγZZ\gamma\gamma couplings we show that the longitudinal polarization state of the final gauge boson improves the sensitivity to anomalous couplings by a factor of 2-3 depending on energy and coupling. An extra enhancement in sensitivity by a factor of 1.3 comes from a set of initial beam polarizations

    The effect of electromagnetic properties of neutrinos on the photon-neutrino decoupling temperature

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    We examine the impact of electromagnetic properties of neutrinos on the annihilation of relic neutrinos with ultra high energy cosmic neutrinos for the ννˉγγ\nu \bar{\nu}\to \gamma\gamma process. For this process, photon-neutrino decoupling temperature is calculated via effective lagrangian model beyond the standard model. We find that photon-neutrino decoupling temperature can be importantly reduced below the QCD phase transition with the model independent analysis defining electromagnetic properties of neutrinos.Comment: 12 pages, 3 figures, published versio

    Reliability and validity of the Turkish version of the Performance-Oriented Mobility Assessment I

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    The Performance-Oriented Mobility Assessment (POMA)-I is widely used assessment tool for evaluation of balance and gait properties. The aim of this study was to translate POMA-I to Turkish and to assess its reliability and validity. People with amputated lower extremities using prosthetics, those who underwent orthopedic surgery within the last 6 months, those dependent on wheel chairs and also bed-ridden patients, subjects with dementia and Alzheimer's disease, and illiterate people were excluded. After translation into Turkish, the Turkish version of the scale was applied on the participants at 2-week intervals. Volunteers ≥65 years of age were enrolled in the study. Internal consistencies of POMA subscale scores of postural balance and gait, and total score were calculated using Cronbach's α coefficient. The Turkish version was evaluated with respect to inter- and intrarater reliability and test-retest reliability intraclass correlation coefficient (ICC). For validation, Pearson's correlation coefficient between POMA and Berg Balance Scale (BBS) and Timed Up and Go Test (TUGT) was estimated. Eighty participants enrolled in the study with a mean age of 76. 5 ± 6. 75 years. In the reliability evaluation of the scale, considering postural balance, gait, and total score, Cronbach's α coefficients were found to be 0. 72, 0. 83, and 0. 88, respectively. ICCs were detected above 0. 70 for test-retest reliability and also for interrater and intrarater reliability. In validation study POMA total score had a strong positive correlation with BBS total score (r = 0. 86, p<0. 0001), and also a negative correlation with TUGT (r = -0. 75, p < 0. 0001). According to the results of this study, the Turkish version of the POMA-I scale has been found to be a reliable and a valid scale for elderly Turkish people. © 2012 European Group for Research into Elderly and Physical Activity (EGREPA)
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