109 research outputs found

    Questionable and Unquestionable in Quantum Mechanics

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    We derive the basic postulates of quantum physics from a few very simple operational assumptions based exclusively on the relative frequencies of observable events (measurement operations and measurement outcomes). We isolate a notion which can be identified with the system's own state, in the sense that it characterizes the system's probabilistic behavior against all possible measurement operations. We investigate some important features of the possible states of the system. All those investigations remain within the framework of classical Kolmogorovian probability theory, meaning that any physical system (traditionally categorized as classical or quantum) that can be described in operational terms can be described within classical Kolmogorovian probability theory. In the second part of the paper we show that anything that can be described in operational terms can, if we wish, be represented in the Hilbert space quantum mechanical formalism. The outcomes of each measurement can be represented by a system of pairwise orthogonal closed subspaces spanning the entire Hilbert space; the states of the system can be represented by pure state operators, and the probabilities of the outcomes can be reproduced by the usual trace formula. Each real valued quantity can be associated with a suitable self-adjoint operator, such that the possible measurement results are the eigenvalues and the outcome events are represented by the eigenspaces, according to the spectral decomposition of the operator in question. This suggests that the basic postulates of quantum theory are in fact analytic statements: they do not tell us anything about a physical system beyond the fact that the system can be described in operational terms. This is almost true. At the end of the paper we discuss a few subtle points where the representation we obtained is not completely identical with standard quantum mechanics.Comment: 40 page

    Effect of the Cretaceous Serra Geral igneous event on the temperatures and heat flow of the Parana Basin, southern Brazil

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    We investigate the effects of the cooling of intrusive and extrusive igneous bodies on the temperature history and surface heat flow of the Parana Basin. The Serra Geral igneous event (130–135 Ma) covered most of this basin with flood basalts. Associated with this event numerous sills and dykes intruded the sediments and basement, and extensive underplating may have occurred in the lower crust and upper mantle beneath the basin. We develop an analytical model of the conductive cooling of tabular intrusive bodies and use it to calculate temperatures within the sediments as a function of time since emplacement. Depending on the thickness of these igneous bodies and the timing of sequential emplacement, the thermal history of a given locus in the basin can range from a simple extended period of higher temperatures to multiple episodes of peak temperatures separated by cooling intervals. The cooling of surface flood basalts, sills and dykes is capable of maintaining temperatures abovc the normal geothermal gradient temperatures for a few hundred thousand years, while large-scale underplating may influence temperatures for up to 10 million years. We conclude that any residual heat from the cooling of the Serra Geral igneous rocks has long since decayed to insignificant values and that present-day temperatures and heat flow are not affected. However, the burial of the sediments beneath the thick basalt cap caused a permanent temperature increase of up to 50°C in the underlying sediments since the beginning of the Cretaceous.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72088/1/j.1365-2117.1994.tb00087.x.pd

    Hamilton-Jacobi quantization of singular Lagrangians with linear velocities

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    In this paper, constrained Hamiltonian systems with linear velocities are investigated by using the Hamilton-Jacobi method. We shall consider the integrablity conditions on the equations of motion and the action function as well in order to obtain the path integral quantization of singular Lagrangians with linear velocities.Comment: late

    Mapping the Relationship Among Political Ideology, CSR Mindset, and CSR Strategy: A Contingency Perspective Applied to Chinese Managers

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    The literature on antecedents of corporate social responsibility (CSR) strategies of firms has been predominately content driven. Informed by the managerial sense-making process perspective, we develop a contingency theoretical framework explaining how political ideology of managers affects the choice of CSR strategy for their firms through their CSR mindset. We also explain to what extent the outcome of this process is shaped by the firm’s internal institutional arrangements and external factors impacting on the firm. We develop and test several hypotheses using data collected from 129 Chinese managers. The results show that managers with a stronger socialist ideology are likely to develop a mindset favouring CSR, which induces the adoption of a proactive CSR strategy. The CSR mindset mediates the link between socialist ideology and CSR strategy. The strength of the relationship between the CSR mindset and the choice of CSR strategy is moderated by customer response to CSR, industry competition, the role of government, and CSR-related managerial incentives

    CMS physics technical design report : Addendum on high density QCD with heavy ions

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    Peer reviewe

    Design, performance, and calibration of the CMS hadron-outer calorimeter

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    Observation of a new boson at a mass of 125 GeV with the CMS experiment at the LHC

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