1,112 research outputs found

    Bell's inequalities for states with positive partial transpose

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    We study violations of n particle Bell inequalities (as developed by Mermin and Klyshko) under the assumption that suitable partial transposes of the density operator are positive. If all transposes with respect to a partition of the system into p subsystems are positive, the best upper bound on the violation is 2^((n-p)/2). In particular, if the partial transposes with respect to all subsystems are positive, the inequalities are satisfied. This is supporting evidence for a recent conjecture by Peres that positivity of partial transposes could be equivalent to existence of local classical models.Comment: 4 pages, REVTe

    Evaluation of non-chemical seed treatment methods for the control of Alternaria dauci and A. radicina on carrot seeds

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    The current study was initiated to evaluate the efficacy of physical methods (hot water, aerated steam, electron treatment) and agents of natural origin (resistance inducers, plant derived products, micro-organisms) as seed treatments of carrots for control of Alternaria dauci and A. radicina. Control of both Alternaria species by seed treatment with the resistance inducers was generally poor. Results were also not satisfactory with most of the formulated commercial micro-organism preparations. Based on the average of five field trials, one of these, BA 2552 (Pseudomonas chlororaphis), provided a low but significant increase in plant stand. Among the experimental micro-organisms, the best results were obtained with Pseudomonas sp. strain MF 416 and Clonostachys rosea strain IK726. A similar level of efficacy was provided by seed treatment with an emulsion (1%) of thyme oil in water. Good and consistent control was generally achieved with the physical methods aerated steam, hot water and electron treatment. Aerated steam treatment was, apart from the thiram-containing chemical standard, the best single treatment, and its performance may at least partially be due to extensive pre-testing, resulting in dosages optimally adapted to the respective seed lot. In some of the experiments the effect of the hot water treatment, which was tested at a fixed, not specifically adapted dosage, was significantly improved when combined with a Pseudomonas sp. MF 416 or C. rosea IK726 treatment. The results are discussed in relation to the outcome of experiments in which the same seed treatment methods and agents were tested in other seed-borne vegetable pathosystems

    Transfer of quantum states using finite resources

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    We discuss the problem of transfering a qubit from Alice to Bob using a noisy quantum channel and only finite resources. As the basic protocol for the transfer we apply quantum teleportation. It turns out that for a certain quality of the channel direct teleportation combined with qubit purification is superior to entanglement purification of the channel. If, however, the quality of the channel is rather low one should simply apply an estimation-preparation scheme.Comment: 9 pages RevTeX including 5 figures, replaced with revised version, to appear in Phys. Rev.

    STOVE: Seed treatments for organic vegetable production

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    The aim of the EU-financed research project „STOVE“ (Seed Treatments for Organic Vegetable Production) is to evaluate different methods potentially suited for seed treatment of vegetables in organic farming regarding their efficacy, to optimise these methods, and where feasible to combine them with each other. Scientists from seven European research institutions and a producer of organic vegetable seeds carry out the project

    South African physiotherapists’ attitudes to medicine prescription as an extension of practice

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    DATA AVAILABILITY : Raw data are available upon request as unedited SPSS data files, including outputs generated from the corresponding author, W.C.BACKGROUND : The extension of medicine prescription rights to other healthcare providers was proposed to reduce pharmacotherapeutic service delivery challenges in the South African healthcare sector. The scope of practice of physiotherapists is being reviewed to possibly include prescription rights to promote service delivery. OBJECTIVES : Our study assessed the attitudes of registered South African physiotherapists to the inclusion of prescription rights in their scope of practice, including enablers and challenges, and the drug classes they believe to be most relevant. METHOD : A cross-sectional descriptive survey of South African registered physiotherapists was completed using an online questionnaire. RESULTS : A total of 359 participants completed the questionnaire, where 88.2% agreed that prescribing rights should be introduced, and 87.64% would want to be trained to prescribe. Participants identified several benefits: improved service delivery (91.3%); reduced healthcare delivery costs (89.8%); decreased need for multiple healthcare practitioner consultations (93.2%). Concerns included: inadequate training (55%); increased workload (18.7%); increased insurance premiums against medical liability claims (46.2%). Drugs of relevance included analgesics (95.6%) and bronchodilators (96.0%), while low preference was placed on drugs unrelated to physiotherapy. Chi-square analysis revealed associations between specific drug classes and fields of expertise. CONCLUSION : South African physiotherapists agree that prescribing and a limited formulary would benefit their scope of practice; however, educational concerns are evident. CLINICAL IMPLICATIONS : Findings support the drive to extend the South African physiotherapy scope of practice, however, investigation will be needed to determine the most appropriate way to capacitate future physiotherapists and current graduates should the extension be approved.http://www.sajp.co.zaam2024PharmacologyPhysiotherapyNon

    Light-Front Quantisation as an Initial-Boundary Value Problem

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    In the light front quantisation scheme initial conditions are usually provided on a single lightlike hyperplane. This, however, is insufficient to yield a unique solution of the field equations. We investigate under which additional conditions the problem of solving the field equations becomes well posed. The consequences for quantisation are studied within a Hamiltonian formulation by using the method of Faddeev and Jackiw for dealing with first-order Lagrangians. For the prototype field theory of massive scalar fields in 1+1 dimensions, we find that initial conditions for fixed light cone time {\sl and} boundary conditions in the spatial variable are sufficient to yield a consistent commutator algebra. Data on a second lightlike hyperplane are not necessary. Hamiltonian and Euler-Lagrange equations of motion become equivalent; the description of the dynamics remains canonical and simple. In this way we justify the approach of discretised light cone quantisation.Comment: 26 pages (including figure), tex, figure in latex, TPR 93-

    Parametrization of projector-based witnesses for bipartite systems

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    Entanglement witnesses are nonpositive Hermitian operators which can detect the presence of entanglement. In this paper, we provide a general parametrization for orthonormal basis of Cn{\mathbb C}^n and use it to construct projector-based witness operators for entanglement detection in the vicinity of pure bipartite states. Our method to parameterize entanglement witnesses is operationally simple and could be used for doing symbolic and numerical calculations. As an example we use the method for detecting entanglement between an atom and the single mode of quantized field, described by the Jaynes-Cummings model. We also compare the detection of witnesses with the negativity of the state, and show that in the vicinity of pure stats such constructed witnesses able to detect entanglement of the state.Comment: 12 pages, four figure

    Nonlinear Inequalities and Entropy-Concurrence Plane

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    Nonlinear inequalities based on the quadratic Renyi entropy for mixed two-qubit states are characterized on the Entropy-Concurrence plane. This class of inequalities is stronger than Clauser-Horne-Shimony-Holt (CHSH) inequalities and, in particular, are violated "in toto" by the set of Type I Maximally-Entangled-Mixture States (MEMS I)
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