899 research outputs found

    Continuity theorems for the M/M/1/nM/M/1/n queueing system

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    In this paper continuity theorems are established for the number of losses during a busy period of the M/M/1/nM/M/1/n queue. We consider an M/GI/1/nM/GI/1/n queueing system where the service time probability distribution, slightly different in a certain sense from the exponential distribution, is approximated by that exponential distribution. Continuity theorems are obtained in the form of one or two-sided stochastic inequalities. The paper shows how the bounds of these inequalities are changed if further assumptions, associated with specific properties of the service time distribution (precisely described in the paper), are made. Specifically, some parametric families of service time distributions are discussed, and the paper establishes uniform estimates (given for all possible values of the parameter) and local estimates (where the parameter is fixed and takes only the given value). The analysis of the paper is based on the level crossing approach and some characterization properties of the exponential distribution.Comment: Final revision; will be published as i

    PDF and scale uncertainties of various DY distributions in ADD and RS models at hadron colliders

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    In the extra dimension models of ADD and RS we study the dependence of the various parton distribution functions on observable of Drell-Yan process to NLO in QCD at LHC and Tevatron energies. Uncertainties at LHC due to factorisation scales in going from leading to next-to-leading order in QCD for the various distributions get reduced by about 2.75 times for a μF\mu_F range 0.5 Q<μF<1.5 Q0.5 ~Q < \mu_F < 1.5 ~Q. Further uncertainties arising from the error on experimental data are estimated using the MRST parton distribution functions.Comment: 27 pages, 11 figures, the version to appear in European Physical Journal

    Regge residues from DGLAP evolution

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    We show that combining forward and backward evolution allows to extract the residues of the triple-pole pomeron and of the other singularities for 10 GeV2Q21000^2 \le Q^2 \le 1000 GeV2^2. In this approach, the essential singularity generated by the DGLAP evolution is considered as a numerical approximation to a triple-pole pomeron. Using an analytical expression for the form factors, we reproduce the experimental data with a χ2/dof\chi^2/dof of 1.02. This proves the compatibility between Regge theory and DGLAP evolution. The method used here enables us to evaluate the uncertainties on the gluon distribution which prove to be large at small xx and small Q2Q^2.Comment: 11 pages, 9 figures, RevTeX 4, Submitted to Phys. Re

    The Transition to a Giant Vortex Phase in a Fast Rotating Bose-Einstein Condensate

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    We study the Gross-Pitaevskii (GP) energy functional for a fast rotating Bose-Einstein condensate on the unit disc in two dimensions. Writing the coupling parameter as 1 / \eps^2 we consider the asymptotic regime \eps \to 0 with the angular velocity Ω\Omega proportional to (\eps^2|\log\eps|)^{-1} . We prove that if \Omega = \Omega_0 (\eps^2|\log\eps|)^{-1} and Ω0>2(3π)1 \Omega_0 > 2(3\pi)^{-1} then a minimizer of the GP energy functional has no zeros in an annulus at the boundary of the disc that contains the bulk of the mass. The vorticity resides in a complementary `hole' around the center where the density is vanishingly small. Moreover, we prove a lower bound to the ground state energy that matches, up to small errors, the upper bound obtained from an optimal giant vortex trial function, and also that the winding number of a GP minimizer around the disc is in accord with the phase of this trial function.Comment: 52 pages, PDFLaTex. Minor corrections, sign convention modified. To be published in Commun. Math. Phy

    DGLAP evolution extends the triple pole pomeron fit

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    We show that the triple pole pomeron model \cite{CMS} provides an initial condition for a DGLAP evolution \cite{DGLAP} that produces a fit to high Q2Q^2 experimental DIS data. We obtain good χ2\chi^2 for initial scales down to 3 GeV2^2. Values of the initial scale smaller than 1.45 GeV2^2 are ruled out at the 90% confidence level.Comment: 8 pages, 6 figures, uses RevTex 4. Typos corrected, some points clarifed and 1 figure adde

    From cheek swabs to consensus sequences : an A to Z protocol for high-throughput DNA sequencing of complete human mitochondrial genomes

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    Background: Next-generation DNA sequencing (NGS) technologies have made huge impacts in many fields of biological research, but especially in evolutionary biology. One area where NGS has shown potential is for high-throughput sequencing of complete mtDNA genomes (of humans and other animals). Despite the increasing use of NGS technologies and a better appreciation of their importance in answering biological questions, there remain significant obstacles to the successful implementation of NGS-based projects, especially for new users. Results: Here we present an ‘A to Z’ protocol for obtaining complete human mitochondrial (mtDNA) genomes – from DNA extraction to consensus sequence. Although designed for use on humans, this protocol could also be used to sequence small, organellar genomes from other species, and also nuclear loci. This protocol includes DNA extraction, PCR amplification, fragmentation of PCR products, barcoding of fragments, sequencing using the 454 GS FLX platform, and a complete bioinformatics pipeline (primer removal, reference-based mapping, output of coverage plots and SNP calling). Conclusions: All steps in this protocol are designed to be straightforward to implement, especially for researchers who are undertaking next-generation sequencing for the first time. The molecular steps are scalable to large numbers (hundreds) of individuals and all steps post-DNA extraction can be carried out in 96-well plate format. Also, the protocol has been assembled so that individual ‘modules’ can be swapped out to suit available resources

    Electron Dynamics in Nd1.85_{1.85}Ce.15_{.15}CuO4+δ_{4+\delta}: Evidence for the Pseudogap State and Unconventional c-axis Response

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    Infrared reflectance measurements were made with light polarized along the a- and c-axis of both superconducting and antiferromagnetic phases of electron doped Nd1.85_{1.85}Ce.15_{.15}CuO4+δ_{4+\delta}. The results are compared to characteristic features of the electromagnetic response in hole doped cuprates. Within the CuO2_2 planes the frequency dependent scattering rate, 1/τ(ω)\tau(\omega), is depressed below \sim 650 cm1^{-1}; this behavior is a hallmark of the pseudogap state. While in several hole doped compounds the energy scales associated with the pseudogap and superconducting states are quite close, we are able to show that in Nd1.85_{1.85}Ce.15_{.15}CuO4+δ_{4+\delta} the two scales differ by more than one order of magnitude. Another feature of the in-plane charge response is a peak in the real part of the conductivity, σ1(ω)\sigma_1(\omega), at 50-110 cm1^{-1} which is in sharp contrast with the Drude-like response where σ1(ω)\sigma_1(\omega) is centered at ω=0\omega=0. This latter effect is similar to what is found in disordered hole doped cuprates and is discussed in the context of carrier localization. Examination of the c-axis conductivity gives evidence for an anomalously broad frequency range from which the interlayer superfluid is accumulated. Compelling evidence for the pseudogap state as well as other characteristics of the charge dynamics in Nd1.85_{1.85}Ce.15_{.15}CuO4+δ_{4+\delta} signal global similarities of the cuprate phase diagram with respect to electron and hole doping.Comment: Submitted to PR

    Astroparticle Physics with a Customized Low-Background Broad Energy Germanium Detector

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    The MAJORANA Collaboration is building the MAJORANA DEMONSTRATOR, a 60 kg array of high purity germanium detectors housed in an ultra-low background shield at the Sanford Underground Laboratory in Lead, SD. The MAJORANA DEMONSTRATOR will search for neutrinoless double-beta decay of 76Ge while demonstrating the feasibility of a tonne-scale experiment. It may also carry out a dark matter search in the 1-10 GeV/c^2 mass range. We have found that customized Broad Energy Germanium (BEGe) detectors produced by Canberra have several desirable features for a neutrinoless double-beta decay experiment, including low electronic noise, excellent pulse shape analysis capabilities, and simple fabrication. We have deployed a customized BEGe, the MAJORANA Low-Background BEGe at Kimballton (MALBEK), in a low-background cryostat and shield at the Kimballton Underground Research Facility in Virginia. This paper will focus on the detector characteristics and measurements that can be performed with such a radiation detector in a low-background environment.Comment: Submitted to NIMA Proceedings, SORMA XII. 9 pages, 4 figure

    Innovations in suicide prevention research (INSPIRE): a protocol for a population-based case–control study

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    Background Suicide deaths have been increasing for the past 20 years in the USA resulting in 45 979 deaths in 2020, a 29% increase since 1999. Lack of data linkage between entities with potential to implement large suicide prevention initiatives (health insurers, health institutions and corrections) is a barrier to developing an integrated framework for suicide prevention. Objectives Data linkage between death records and several large administrative datasets to (1) estimate associations between risk factors and suicide outcomes, (2) develop predictive algorithms and (3) establish long-term data linkage workflow to ensure ongoing suicide surveillance. Methods We will combine six data sources from North Carolina, the 10th most populous state in the USA, from 2006 onward, including death certificate records, violent deaths reporting system, large private health insurance claims data, Medicaid claims data, University of North Carolina electronic health records and data on justice involved individuals released from incarceration. We will determine the incidence of death from suicide, suicide attempts and ideation in the four subpopulations to establish benchmarks. We will use a nested case–control design with incidence density-matched population-based controls to (1) identify short-term and long-term risk factors associated with suicide attempts and mortality and (2) develop machine learning-based predictive algorithms to identify individuals at risk of suicide deaths. Discussion We will address gaps from prior studies by establishing an in-depth linked suicide surveillance system integrating multiple large, comprehensive databases that permit establishment of benchmarks, identification of predictors, evaluation of prevention efforts and establishment of long-term surveillance workflow protocols

    Observation of a new chi_b state in radiative transitions to Upsilon(1S) and Upsilon(2S) at ATLAS

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    The chi_b(nP) quarkonium states are produced in proton-proton collisions at the Large Hadron Collider (LHC) at sqrt(s) = 7 TeV and recorded by the ATLAS detector. Using a data sample corresponding to an integrated luminosity of 4.4 fb^-1, these states are reconstructed through their radiative decays to Upsilon(1S,2S) with Upsilon->mu+mu-. In addition to the mass peaks corresponding to the decay modes chi_b(1P,2P)->Upsilon(1S)gamma, a new structure centered at a mass of 10.530+/-0.005 (stat.)+/-0.009 (syst.) GeV is also observed, in both the Upsilon(1S)gamma and Upsilon(2S)gamma decay modes. This is interpreted as the chi_b(3P) system.Comment: 5 pages plus author list (18 pages total), 2 figures, 1 table, corrected author list, matches final version in Physical Review Letter
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