44,805 research outputs found

    Axiom System and Completeness Expression for Quantum Mechanics

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    The standard axiomatization of quantum mechanics (QM) is not fully explicit about the role of the time-parameter. Especially, the time reference within the probability algorithm (the Born Rule, BR) is unclear. Using a plausible principle P1, about the role of probability in a physical theory, and a second principle P2 affording a most natural way to make BR precise, a logical conflict with the standard expression for the completeness of QM can be derived. Rejecting P1 is implausible. Rejecting P2 leads to unphysical results and to a conflict with a generalization of P2, a principle P3. It is thus made plausible that the standard expression of QM completeness must be revised. An absolutely explicit form of the axioms is provided, including a precise form of the projection postulate. An appropriate expression for QM completeness, reflecting the restrictions of the Gleason and Kochen-Specker theorems is proposed.Comment: 20 pages, no figure

    Figura...or Face? Reflections on Two Sociopragmatic Key Concepts in the Light of a Recent Media Conflict Between Italians and Germans and Its Negotiation in Italian Internet Forums

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    This study will contrast the notions of figura and face. It reflects two Sociopragmatic Key Concepts in the Light of a Recent Media Conflict between Italians and Germans and its Negotiation in Italian Internet Forums

    Localization of strongly correlated electrons as Jahn-Teller polarons in manganites

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    A realistic modeling of manganites should include the Coulomb repulsion between ege_g electrons, the Hund's rule coupling to t2gt_{2g} spins, and Jahn-Teller phonons. Solving such a model by dynamical mean field theory, we report large magnetoresistances and spectra in good agreement with experiments. The physics of the unusual, insulating-like paramagnetic phase is determined by correlated electrons which are-due to strong correlations-easily trapped as Jahn-Teller polarons.Comment: 4 pages, 3 figure

    Bayesian Modelling of Inseparable Space-Time Variation in Disease Risk

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    This paper proposes a unified framework for a Bayesian analysis of incidence or mortality data in space and time. We introduce four different types of prior distributions for space ×\times time interaction in extension of a model with only main effects. Each type implies a certain degree of prior dependence for the interaction parameters, and corresponds to the product of one of the two spatial with one of the two temporal main effects. The methodology is illustrated by an analysis of Ohio lung cancer data 1968-88 via Markov chain Monte Carlo simulation. We compare the fit and the complexity of several models with different types of interaction by means of quantities related to the posterior deviance. Our results confirm an epidemiological hypothesis about the temporal development of the association between urbanization and risk factors for cancer

    Top mass from asymptotic safety

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    We discover that asymptotically safe quantum gravity could predict the top-quark mass. For a broad range of microscopic gravitational couplings, quantum gravity could provide an ultraviolet completion for the Standard Model by triggering asymptotic freedom in the gauge couplings and bottom Yukawa and asymptotic safety in the top-Yukawa and Higgs-quartic coupling. We find that in a part of this range, a difference of the top and bottom mass of approximately 170GeV170\, \rm GeV is generated and the Higgs mass is determined in terms of the top mass. Assuming no new physics below the Planck scale, we construct explicit Renormalization Group trajectories for Standard Model and gravitational couplings which link the transplanckian regime to the electroweak scale and yield a top pole mass of Mt,pole171GeVM_\text{t,pole} \approx 171\, \rm GeV.Comment: Matches version accepted in Phys. Lett. B; counting of degrees of freedom in Eq.(7) changed, resulting in M_t=171 GeV and M_h=132 GeV; conclusions unchange

    A Bayesian geoadditive relative survival analysis of registry data on breast cancer mortality

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    In this paper we develop a so called relative survival analysis, that is used to model the excess risk of a certain subpopulation relative to the natural mortality risk, i.e. the base risk that is present in the whole population. Such models are typically used in the area of clinical studies, that aim at identifying prognostic factors for disease specific mortality with data on specific causes of death being not available. Our work has been motivated by continuous-time spatially referenced survival data on breast cancer where causes of death are not known. This paper forms an extension of the analyses presented in Sauleau et al. (2007), where those data are analysed via a geoadditive, semiparametric approach, however without allowance to incorporate natural mortality. The usefulness of this relative survival approach is supported by means of a simulated data set

    Two-Level Rectilinear Steiner Trees

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    Given a set PP of terminals in the plane and a partition of PP into kk subsets P1,...,PkP_1, ..., P_k, a two-level rectilinear Steiner tree consists of a rectilinear Steiner tree TiT_i connecting the terminals in each set PiP_i (i=1,...,ki=1,...,k) and a top-level tree TtopT_{top} connecting the trees T1,...,TkT_1, ..., T_k. The goal is to minimize the total length of all trees. This problem arises naturally in the design of low-power physical implementations of parity functions on a computer chip. For bounded kk we present a polynomial time approximation scheme (PTAS) that is based on Arora's PTAS for rectilinear Steiner trees after lifting each partition into an extra dimension. For the general case we propose an algorithm that predetermines a connection point for each TiT_i and TtopT_{top} (i=1,...,ki=1,...,k). Then, we apply any approximation algorithm for minimum rectilinear Steiner trees in the plane to compute each TiT_i and TtopT_{top} independently. This gives us a 2.372.37-factor approximation with a running time of O(PlogP)\mathcal{O}(|P|\log|P|) suitable for fast practical computations. The approximation factor reduces to 1.631.63 by applying Arora's approximation scheme in the plane
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