1,134 research outputs found

    Entanglement of two qubits in a relativistic orbit

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    The creation and destruction of entanglement between a pair of interacting two-level detectors accelerating about diametrically opposite points of a circular path is investigated. It is found that any non-zero acceleration has the effect of suppressing the vacuum entanglement and enhancing the acceleration radiation thereby reducing the entangling capacity of the detectors. Given that for large accelerations the acceleration radiation is the dominant effect, we investigate the evolution of a two detector system initially prepared in a Bell state using a perturbative mater equation and treating the vacuum fluctuations as an unobserved environment. A general function for the concurrence is obtained for stationary and symmetric worldlines in flatspace. The entanglement sudden death time is computed.Comment: v2: Some typo's fixed, figures compressed to smaller filesize and added some references

    Security Analysis, Agency Costs, and UK Firm Characteristics

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    This paper assesses the monitoring power of security analysts from the manager-shareholder conflict perspective. Using a sample of UK firms tracked by security analysts, our evidence supports the view that security analysis acts as a monitoring mechanism in reducing agency costs. We also find that security analysts are more effective in reducing agency costs for smaller and more focused firms rather than larger and more diversified firms suggesting that for larger and more complex firms security analysis is less effective. The UK findings suggest that the monitoring role of security analysts is not restricted to the U.S. capital market environment.

    Quasi-normal modes for doubly rotating black holes

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    Based on the work of Chen, L\"u and Pope, we derive expressions for the D6D\geq 6 dimensional metric for Kerr-(A)dS black holes with two independent rotation parameters and all others set equal to zero: a10,a20,a3=a4=...=0a_1\neq 0, a_2\neq0, a_3=a_4=...=0. The Klein-Gordon equation is then explicitly separated on this background. For D6D\geq 6 this separation results in a radial equation coupled to two generalized spheroidal angular equations. We then develop a full numerical approach that utilizes the Asymptotic Iteration Method (AIM) to find radial Quasi-Normal Modes (QNMs) of doubly rotating flat Myers-Perry black holes for slow rotations. We also develop perturbative expansions for the angular quantum numbers in powers of the rotation parameters up to second order.Comment: RevTeX 4-1, various figure

    The design and use of the Bioethics Consultation Form

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    The emergence of the ethics consultation as a means to resolve moral crises in clinical medicine has revealed the need for a worksheet that would facilitate intake and analysis. The author developed the “Bioethics Consultation Form” as an attempt to remedy this need. The form is arranged in an outline format and is a useful asset to ethics committee discussions and record keeping. The first section covers basic intake data concerning the patient's medical and personal information, advance directives, and values, as well as the values of the physician and family. After the intake section is completed with the above data, the ethics consultant then turns to the analysis section. This second section allows for (1) the discussion of conflicting values, (2) the identification of priorities, and (3) the elucidation of ethical norms relevant to the case.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43229/1/11017_2004_Article_BF00489215.pd

    Loss of Spin Entanglement For Accelerated Electrons in Electric and Magnetic Fields

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    Using an open quantum system we calculate the time dependence of the concurrence between two maximally entangled electron spins with one accelerated uniformly in the presence of a constant magnetic field and the other at rest and isolated from fields. We find at high Rindler temperature the proper time for the entanglement to be extinguished is proportional to the inverse of the acceleration cubed.Comment: 10 pages, 4 figures, appendix and other discussion added, fixed some typographical errors and some references were correcte

    Identification of a polymer growth process with an equilibrium multi-critical collapse phase transition: the meeting point of swollen, collapsed and crystalline polymers

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    We have investigated a polymer growth process on the triangular lattice where the configurations produced are self-avoiding trails. We show that the scaling behaviour of this process is similar to the analogous process on the square lattice. However, while the square lattice process maps to the collapse transition of the canonical interacting self-avoiding trail model (ISAT) on that lattice, the process on the triangular lattice model does not map to the canonical equilibrium model. On the other hand, we show that the collapse transition of the canonical ISAT model on the triangular lattice behaves in a way reminiscent of the θ\theta-point of the interacting self-avoiding walk model (ISAW), which is the standard model of polymer collapse. This implies an unusual lattice dependency of the ISAT collapse transition in two dimensions. By studying an extended ISAT model, we demonstrate that the growth process maps to a multi-critical point in a larger parameter space. In this extended parameter space the collapse phase transition may be either θ\theta-point-like (second-order) or first-order, and these two are separated by a multi-critical point. It is this multi-critical point to which the growth process maps. Furthermore, we provide evidence that in addition to the high-temperature gas-like swollen polymer phase (coil) and the low-temperature liquid drop-like collapse phase (globule) there is also a maximally dense crystal-like phase (crystal) at low temperatures dependent on the parameter values. The multi-critical point is the meeting point of these three phases. Our hypothesised phase diagram resolves the mystery of the seemingly differing behaviours of the ISAW and ISAT models in two dimensions as well as the behaviour of the trail growth process

    The morphomolecular features of cholangiocarcinoma in the personalised era

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    Cholangiocarcinoma is a group of diverse invasive malignancies arising along the biliary tract. The outcomes for patients with cholangiocarcinoma remain poor but an understanding of molecular aberrations and subsequent targeted therapies to these have opened up new treatment prospects. This review describes the clinical and morphological features and classifications of intrahepatic and perihilar cholangiocarcinoma in addition to laying out the related landscape of the molecular pathology within cholangiocarcinoma. The importance of both a high index of suspicion of cholangiocarcinoma and preserving tissue whilst reporting to access molecular testing and personalised treatment pathways is emphasised

    Scalar spheroidal harmonics in five dimensional Kerr-(A)dS

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    We derive expressions for the general five-dimensional metric for Kerr-(A)dS black holes. The Klein-Gordon equation is explicitly separated and we show that the angular part of the wave equation leads to just one spheroidal wave equation, which is also that for charged five-dimensional Kerr-(A)dS black holes. We present results for the perturbative expansion of the angular eigenvalue in powers of the rotation parameters up to 6th order and compare numerically with the continued fraction method.Comment: 11 pages, two figures, one table; vz. 2: reference added and grammar correcte
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