294 research outputs found

    From controlled trials to clinical practice: monitoring transmyocardial revascularization use and outcomes

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    Entangled Light in Moving Frames

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    We calculate the entanglement between a pair of polarization-entangled photon beams as a function of the reference frame, in a fully relativistic framework. We find the transformation law for helicity basis states and show that, while it is frequency independent, a Lorentz transformation on a momentum-helicity eigenstate produces a momentum-dependent phase. This phase leads to changes in the reduced polarization density matrix, such that entanglement is either decreased or increased, depending on the boost direction, the rapidity, and the spread of the beam.Comment: 4 pages and 3 figures. Minor corrections, footnote on optimal basis state

    How to observe a coherent superposition of an atom and a molecule

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    We demonstrate that it is possible, in principle, to perform a Ramsey-type interference experiment to exhibit a coherent superposition of a single atom and a diatomic molecule. This gedanken experiment, based on the techniques of Aharonov and Susskind [Phys. Rev. 155, 1428 (1967)], explicitly violates the commonly-accepted superselection rule that forbids coherent superpositions of eigenstates of differing atom number. This interference experiment makes use of a Bose-Einstein condensate as a reference frame with which to perform the coherent operations analogous to Ramsey pulses. We also investigate an analogous gedanken experiment to exhibit a coherent superposition of a single boson and a fermion, violating the commonly-accepted superselection rule forbidding coherent superpositions of states of differing particle statistics; in this case, the reference frame is realized by a multi-mode state of many fermions. This latter case reproduces all of the relevant features of Ramsey interferometry, including Ramsey fringes over many repetitions of the experiment. However, the apparent inability of this proposed experiment to produce well-defined relative phases between two distinct systems each described by a coherent superposition of a boson and a fermion demonstrates that there are additional, outstanding requirements to fully ``lift'' the univalence superselection rule.Comment: 17 pages, 1 figure, comments welcome, published version (minor changes

    Quantum dynamics in ultra-cold atomic physics

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    We review recent developments in the theory of quantum dynamics in ultra-cold atomic physics, including exact techniques, but focusing on methods based on phase-space mappings that are appli- cable when the complexity becomes exponentially large. These phase-space representations include the truncated Wigner, positive-P and general Gaussian operator representations which can treat both bosons and fermions. These phase-space methods include both traditional approaches using a phase-space of classical dimension, and more recent methods that use a non-classical phase-space of increased dimensionality. Examples used include quantum EPR entanglement of a four-mode BEC, time-reversal tests of dephasing in single-mode traps, BEC quantum collisions with up to 106 modes and 105 interacting particles, quantum interferometry in a multi-mode trap with nonlinear absorp- tion, and the theory of quantum entropy in phase-space. We also treat the approach of variational optimization of the sampling error, giving an elementary example of a nonlinear oscillator

    Prioritising Informed Health Choices Key Concepts for those impacted by cancer: a protocol [version 1; peer review: 2 approved]

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    Background: Few areas of health have been as insidiously influenced by misinformation as cancer. Thus, interventions that can help people impacted by cancer reduce the extent to which they are victims of misinformation are necessary. The Informed Health Choices (IHC) initiative has developed Key Concepts that can be used in the development of interventions for evaluating the trustworthiness of claims about the effects of health treatments. We are developing an online education programme called Informed Health Choices-Cancer (IHC-C) based on the IHC Key Concepts. We will provide those impacted by cancer with the knowledge and skills necessary to think critically about the reliability of health information and claims and make informed choices. Methods: We will establish a steering group (SG) of 12 key stakeholders, including oncology specialists and academics. In addition, we will establish a patient and public involvement (PPI) panel of 20 people impacted by cancer. After training the members on the Key Concepts and the prioritisation process, we will conduct a two-round prioritisation process. In the first round, 12 SG members and four PPI panel members will prioritise Key Concepts for inclusion. In the second round, the remaining 16 PPI members will undertake the prioritisation based on the prioritised Key Concepts from the first round. Participants in both rounds will use a structured judgement form to rate the importance of the Key Concepts for inclusion in the online IHC-C programme. A consensus meeting will be held, where members will reach a consensus on the Key Concepts to be included and rank the order in which the prioritised Key Concepts will be addressed in the IHC-C programme. Conclusions: At the end of this process, we will identify which Key Concepts should be included and the order in which they should be addressed in the IHC-C programme

    Reader technique as a source of variability in determining malaria parasite density by microscopy

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    BACKGROUND: Accurate identification and quantification of malaria parasites are critical for measuring clinical trial outcomes. Positive and negative diagnosis is usually sufficient for the assessment of therapeutic outcome, but vaccine or prophylactic drug trials require measuring density of infection as a primary endpoint. Microscopy is the most established and widely-used technique for quantifying parasite densities in the blood. METHODS: Results obtained by 24–27 expert malaria microscopists, who had independently read 895 slides from 35 donors, were analysed to understand how reader technique contributes to discrepancy in measurements of parasite density over a wide range of densities. RESULTS: Among these 35 donations, standard deviations ranged from 30% to 250% of the mean parasite density and the percent discrepancy was inversely correlated with the mean parasite density. The number of white blood cells indexed and whether parasites were counted in the thick film or thin film were shown to significantly contribute to discrepancy amongst microscopists. CONCLUSION: Errors in microscopy measurements are not widely appreciated or addressed but have serious consequences for efficacy trials, including possibly abandoning promising vaccine candidates

    Marketing Actions and the Value of Customer Assets: A Framework for Customer Asset Management

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    This article develops a framework for assessing how marketing actions affect customers’lifetime value to the firm. The framework is organized around four critical actions that firms must take to effectively manage the asset value of the customer base: database creation, market segmentation, forecasting customer purchase behavior, and resource allocation. In this framework, customer lifetime value is treated as a dynamic construct, that is, it influences the eventual allocation of marketing resources but is also influenced by that allocation. By viewing customers as assets and systematically managing these assets, a firm can identify the most appropriate marketing actions to acquire, maintain, and enhance customer assets and thereby maximize financial returns. The article discusses in detail how to assess customer lifetime value and manage customers as assets. Then, it identifies key research challenges in studying customer asset management and the managerial challenges associated with implementing effective customer asset management practices.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline

    Maxwell Duality, Lorentz Invariance, and Topological Phase

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    We discuss the Maxwell electromagnetic duality relations between the Aharonov-Bohm, Aharonov-Casher, and He-McKellar-Wilkens topological phases, which allows a unified description of all three phenomena. We also elucidate Lorentz transformations that allow these effects to be understood in an intuitive fashion in the rest frame of the moving quantum particle. Finally, we propose two experimental schemes for measuring the He-McKellar-Wilkens phase.Comment: 10 pages, 2 figure
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