16,232 research outputs found

    On the Connection Between Momentum Cutoff and Operator Cutoff Regularizations

    Full text link
    Operator cutoff regularization based on the original Schwinger's proper-time formalism is examined. By constructing a regulating smearing function for the proper-time integration, we show how this regularization scheme simulates the usual momentum cutoff prescription yet preserves gauge symmetry even in the presence of the cutoff scales. Similarity between the operator cutoff regularization and the method of higher (covariant) derivatives is also observed. The invariant nature of the operator cutoff regularization makes it a promising tool for exploring the renormalization group flow of gauge theories in the spirit of Wilson-Kadanoff blocking transformation.Comment: 28 pages in plain TeX, no figures. revised and expande

    Characterisation of an n-type segmented BEGe detector

    Full text link
    A four-fold segmented n-type point-contact "Broad Energy" high-purity germanium detector, SegBEGe, has been characterised at the Max-Planck-Institut f\"ur Physik in Munich. The main characteristics of the detector are described and first measurements concerning the detector properties are presented. The possibility to use mirror pulses to determine source positions is discussed as well as charge losses observed close to the core contact

    Constraints on Non-Commutative Physics Scale with Neutrino-Electron Scattering

    Get PDF
    Neutrino-electron scatterings (νe\nu - e) are purely leptonic processes with robust Standard Model (SM) predictions. Their measurements can therefore provide constraints to physics beyond SM. Non-commutative (NC) field theories modify space-time commutation relations, and allow neutrino electromagnetic couplings at the tree level. Their contribution to neutrino-electron scattering cross-section was derived. Constraints were placed on the NC scale parameter ΛNC\Lambda_{NC} from νe\nu - e experiments with reactor and accelerator neutrinos. The most stringent limit of ΛNC>3.3TeV\Lambda_{NC} > 3.3 TeV at 95% confidence level improves over the direct bounds from collider experiments.Comment: 6 pages, 2 figures, 2 tables, V2: minor revisions to match published versio

    Managing urban flood resilience through the English planning system: insights from the ‘SuDS-face'

    Get PDF
    In academic and professional circles, ‘resilience thinking’ has emerged as the dominant paradigm in flood risk management, which emphasizes the need to plan and design cities that can absorb water and replicate natural processes more closely. In this paper, we explore how planners in England are expected to respond to the resilience agenda against the realities in practice, zoning in on the delivery of sustainable (urban) drainage systems (SuDS). Our exploration highlights that, while SuDS are being implemented, they are largely characterized by a ‘bog standard’ design. We found that there are three main institutional factors that are constraining the implementation of SuDS: the lack of legislative backing, the power afforded to private commercial interests in the neoliberalized planning process, compounded by the severe lack of resources in local authorities. What is missing at the moment is SuDS process and design that is flexible, integrated, collaborative and innovative. There are clear implications that, without the necessary institutional support, resilience thinking will remain largely aspirational, and professionals will struggle to gain traction and translate the larger flood resilience policy agenda into England's future climate-resilient places

    Investigation into O(N) Invariant Scalar Model Using Auxiliary-Mass Method at Finite Temperature

    Get PDF
    Using auxiliary-mass method, O(N) invariant scalar model is investigated at finite temperature. This mass and an evolution equation allow us to calculate an effective potential without an infrared divergence. Second order phase transition is indicated by the effective potential. The critical exponents are determined numerically.Comment: LaTex 8 pages with 3 eps figure

    On the stability of two-chunk file-sharing systems

    Full text link
    We consider five different peer-to-peer file sharing systems with two chunks, with the aim of finding chunk selection algorithms that have provably stable performance with any input rate and assuming non-altruistic peers who leave the system immediately after downloading the second chunk. We show that many algorithms that first looked promising lead to unstable or oscillating behavior. However, we end up with a system with desirable properties. Most of our rigorous results concern the corresponding deterministic large system limits, but in two simplest cases we provide proofs for the stochastic systems also.Comment: 19 pages, 7 figure

    Joint source-channel coding for a quantum multiple access channel

    Get PDF
    Suppose that two senders each obtain one share of the output of a classical, bivariate, correlated information source. They would like to transmit the correlated source to a receiver using a quantum multiple access channel. In prior work, Cover, El Gamal, and Salehi provided a combined source-channel coding strategy for a classical multiple access channel which outperforms the simpler "separation" strategy where separate codebooks are used for the source coding and the channel coding tasks. In the present paper, we prove that a coding strategy similar to the Cover-El Gamal-Salehi strategy and a corresponding quantum simultaneous decoder allow for the reliable transmission of a source over a quantum multiple access channel, as long as a set of information inequalities involving the Holevo quantity hold.Comment: 21 pages, v2: minor changes, accepted into Journal of Physics

    Renormalization Group Flow Equations and the Phase Transition in O(N)-models

    Get PDF
    We derive and solve flow equations for a general O(N)-symmetric effective potential including wavefunction renormalization corrections combined with a heat-kernel regularization. We investigate the model at finite temperature and study the nature of the phase transition in detail. Beta functions, fixed points and critical exponents \beta, \nu, \delta and \eta for various N are independently calculated which allow for a verification of universal scaling relations.Comment: 34 pages, 3 tables, 11 postscript figures, LaTe

    Associations between body mass index and serum levels of C-reactive protein

    Get PDF
    Background. Obesity leads to increased risk of cardiovascular disease and glucose intolerance, which are phenomena of chronic inflammation. This study was performed to determine whether a higher body mass index (BMI) and central obesity are associated with low-grade inflammation.Methods. An analysis of 8 453 adults aged .20 years was performed. Every subject completed a household interview and a questionnaire regarding personal health, and their BMI and serum C-reactive protein (CRP) level were measured. The BMI data were divided into quintiles, using multiple linear regression to estimate the relationship between CRP level and BMI quintiles. An extended-model approach was used forcovariate adjustment. The association between central obesity and CRP level was examined by this method as well.Results. After controlling for demographics, chronic diseases, health behaviours and levels of folate and vitamin B12, the ƒÀ coefficient (which represents the change of naturallog- transformed levels of CRP for each kg/m2 increase in BMI) was 0.078 (
    corecore