173 research outputs found

    A Phylogenetic Analysis of the Family Pseudonocardiaceae and the Genera Actinokineospora and Saccharothrix with 16s rRNA Sequences and a Proposal To Combine the Genera Amycolata and Pseudonocardia in an Emended Genus Pseudonocardia

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    The 16S rRNAs of 15 species of actinomycetes belonging to the genera Actinokineospora and Saccharothrix and the family Pseudonocardiaceae, including Amycolatopsis, Amycolata, Pseudonocardia, Saccharomonospora, and Saccharopolyspora species, were sequenced by using reverse transcriptase. The sequences were analyzed along with the sequences of reference actinomycetes by using distance matrix and parsimony methods. The wall chemotype IV genus Actinokineospora was found to be closely related to species of the genus Saccharothrix which have chemotype III walls. Together, these two genera formed a clade which was closely related to members of the family Pseudonocardiaceae which have chemotype IV walls. However, the phylogenetic branching pattern did not unambiguously resolve whether the members of all three taxa should be placed in a single family. We suggest, therefore, that the genera Actinokineospora and Saccharothrix should remain outside the family Pseudonocardiaceae until additional sequence or phenotypic data are available to decide the issue. The sequences of species belonging to the genera Amycolata and Pseudonocardia were always recovered as a mixed group in phylogenetic trees, and we propose that these organisms should be classified in an emended genus Pseudonocardia. This proposal is strongly supported by previously published lipid, ribosomal protein, and ultrastructure data

    Quantum and classical fidelities for Gaussian states

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    We examine the physical significance of fidelity as a measure of similarity for Gaussian states, by drawing a comparison with its classical counterpart. We find that the relationship between these classical and quantum fidelities is not straightforward, and in general does not seem to provide insight into the physical significance of quantum fidelity. To avoid this ambiguity we propose that the efficacy of quantum information protocols be characterized by determining their transfer function and then calculating the fidelity achievable for a hypothetical pure reference input state.Comment: 9 pages, 5 figures, to be published in J. Opt. Soc. Am. B special issue on Optical Quantum Information Scienc

    Quantum Cryptography without Switching

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    We propose a new coherent state quantum key distribution protocol that eliminates the need to randomly switch between measurement bases. This protocol provides significantly higher secret key rates with increased bandwidths than previous schemes that only make single quadrature measurements. It also offers the further advantage of simplicity compared to all previous protocols which, to date, have relied on switching.Comment: 4 pages, 4 figures, Submitte

    Exergy accounting: a quantitative comparison of methods and implications for energy-economy analysis

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    Assessments of the feasibility of decoupling energy consumption from economic growth could benefit from an improved understanding of the size, nature and value of different energy flows. This understanding may be enhanced by focusing upon so-called “useful exergy”—a measure of both the quantity and “quality” of energy (defined here as its thermodynamic ability to perform physical work) at the “useful” stage of the energy conversion chain. Useful exergy flows within national economies are increasingly being quantified and their role in economic activity explored. However, this so-called “exergy economics” field currently lacks a consistent methodology. This paper contributes to the development of a more consistent approach. By constructing a “useful exergy account” for the United Kingdom covering the period 1960–2012, we explore how different methodological choices influence estimates of useful exergy for different categories of end-use as well as estimates of total national useful exergy consumption. Specifically, we evaluate the sensitivity of estimates to: (a) the method of estimating the exergy efficiency of different end-uses; (b) the boundaries between end-use categories; and (c) the method of estimating the primary exergy associated with renewable electricity. We also improve upon the current method of accounting for industrial uses of heat. This leads to suggestions for best practice when constructing useful exergy accounts, and the identification of areas where further methodological development is required

    Mutual information--based approach to adaptive homodyne detection of quantum optical states

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    I propose an approach to adaptive homodyne detection of digitally modulated quantum optical pulses in which the phase of the local oscillator is chosen to maximize the average information gain, i.e., the mutual information, at each step of the measurement. I study the properties of this adaptive detection scheme by considering the problem of classical information content of ensembles of coherent states. Using simulations of quantum trajectories and visualizations of corresponding measurement operators, I show that the proposed measurement scheme adapts itself to the features of each ensemble. For all considered ensembles of coherent states, it consistently outperforms heterodyne detection and Wiseman's adaptive scheme for phase measurements [H.M. Wiseman, Phys. Rev. Lett. 75, 4587 (1995)].Comment: Submutted to Phys. Rev.

    Ocean warming affects the distribution and abundance of resident fishes by changing their reproductive scope

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    With ocean warming predicted globally, one of the mechanisms driving distributional shifts and changes in the abundance of resident fishes is reproductive output. The relationship between sea surface temperature and the reproductive activity of a eurythermic, resident coastal species, blacktail seabream Diplodus sargus capensis, was examined in the ‘‘ocean warming’’ hotspot of the northern Benguela. Reproductive activity was found to be restricted to periods when the water temperature dropped below 20 _C. A metadata analysis conducted on the D. sargus sub-species complex similarly showed that reproductive activity was restricted to temperatures between 15 and 20 _C, regardless of the range in ambient water temperature. Based on these findings and using satellite derived SST information, we examined D. s. capensis’s total and seasonal ‘‘reproductive scope’’ that is defined as either the area suitable for spawning each year or the duration of its potential spawning season at a fixed geographical locality, respectively. Trends were examined over the last three decades. Reproductive scope by area was found to be shrinking at a rate of 7 % per decade in southern Angola and expanding at a rate of 6 % per decade in northern Namibia. Reproductive scope by season decreased by 1.05 months per decade in Namibe, southern Angola and increased by 0.76 months per decade in Hentiesbaai, northern Namibia. Changes in reproductive scope may be a driving mechanism of distributional shifts in resident fishes, although the rate of the shifts is likely to be slow. More importantly, changes in reproductive scope will not be uniform throughout fish distributions and will most likely result in heterogeneous variations in fish abundance

    Bilateral Remote Ischaemic Conditioning in Children (BRICC) trial:protocol for a two-centre, double-blind, randomised controlled trial in young children undergoing cardiac surgery

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    IntroductionMyocardial protection against ischaemic-reperfusion injury is a key determinant of heart function and outcome following cardiac surgery in children. However, with current strategies, myocardial injury occurs routinely following aortic cross-clamping, as demonstrated by the ubiquitous rise in circulating troponin. Remote ischaemic preconditioning, the application of brief, non-lethal cycles of ischaemia and reperfusion to a distant organ or tissue, is a simple, low-risk and readily available technique which may improve myocardial protection. The Bilateral Remote Ischaemic Conditioning in Children (BRICC) trial will assess whether remote ischaemic preconditioning, applied to both lower limbs immediately prior to surgery, reduces myocardial injury in cyanotic and acyanotic young children.Methods and analysisThe BRICC trial is a two-centre, double-blind, randomised controlled trial recruiting up to 120 young children (age 3 months to 3 years) undergoing primary repair of tetralogy of Fallot or surgical closure of an isolated ventricular septal defect. Participants will be randomised in a 1:1 ratio to either bilateral remote ischaemic preconditioning (3×5 min cycles) or sham immediately prior to surgery, with follow-up until discharge from hospital or 30 days, whichever is sooner. The primary outcome is reduction in area under the time-concentration curve for high-sensitivity (hs) troponin-T release in the first 24 hours after aortic cross-clamp release. Secondary outcome measures include peak hs-troponin-T, vasoactive inotrope score, arterial lactate and central venous oxygen saturations in the first 12 hours, and lengths of stay in the paediatric intensive care unit and the hospital.Ethics and disseminationThe trial was approved by the West Midlands-Solihull National Health Service Research Ethics Committee (16/WM/0309) on 5 August 2016. Findings will be disseminated to the academic community through peer-reviewed publications and presentation at national and international meetings. Parents will be informed of the results through a newsletter in conjunction with a local charity.Trial registration numberISRCTN12923441

    Experimental investigation of continuous variable quantum teleportation

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    We report the experimental demonstration of quantum teleportation of the quadrature amplitudes of a light field. Our experiment was stably locked for long periods, and was analyzed in terms of fidelity, F; and with signal transfer, T_{q}=T^{+}+T^{-}, and noise correlation, V_{q}=V_{in|out}^{+} V_{in|out}^{-}. We observed an optimum fidelity of 0.64 +/- 0.02, T_{q}= 1.06 +/- 0.02 and V_{q} =0.96 +/- 0.10. We discuss the significance of both T_{q}>1 and V_{q}<1 and their relation to the teleportation no-cloning limit.Comment: 4 pages, 4 figure

    Aspects of the biology and fisheries of an economically important sparid Dentex macrophthalmus (Bloch 1791) in the Namibe province, Angola

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    Dentex macrophthalmus is a small, commercially important sparid fish that is abundant in the deeper waters (range 50–500 m) of the Mediterranean Sea (Trunov 1970), the North-West African shelf (Goode and Bean 1896, Fowler 1936), including the Cape Verde and Canary Islands, and the south-eastern Atlantic from the Equator to just south of Lüderitz (27°40′ S) (Trunov 1970). Because of its high abundance, it is of considerable economic importance and is captured in large numbers in both artisanal and commercial fisheries in many countries. Although it is the most important artisanal species along the entire Angolan coast, it is most abundant in the southern region (Kilongo et al. 2007). Despite its economic importance in Angola and elsewhere, relatively little is known on its abundance, fisheries and biology

    Continuous variable polarization entanglement, experiment and analysis

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    We generate and characterise continuous variable polarization entanglement between two optical beams. We first produce quadrature entanglement, and by performing local operations we transform it into a polarization basis. We extend two entanglement criteria, the inseparability criteria proposed by Duan {\it et al.}\cite{Duan00} and the Einstein-Podolsky-Rosen paradox criteria proposed by Reid and Drummond\cite{Reid88}, to Stokes operators; and use them to charactise the entanglement. Our results for the Einstein-Podolsky-Rosen paradox criteria are visualised in terms of uncertainty balls on the Poincar\'{e} sphere. We demonstrate theoretically that using two quadrature entangled pairs it is possible to entangle three orthogonal Stokes operators between a pair of beams, although with a bound 3\sqrt{3} times more stringent than for the quadrature entanglement.Comment: 12 pages, 13 figure
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