5,935 research outputs found

    Complete physical simulation of the entangling-probe attack on the BB84 protocol

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    We have used deterministic single-photon two qubit (SPTQ) quantum logic to implement the most powerful individual-photon attack against the Bennett-Brassard 1984 (BB84) quantum key distribution protocol. Our measurement results, including physical source and gate errors, are in good agreement with theoretical predictions for the Renyi information obtained by Eve as a function of the errors she imparts to Alice and Bob's sifted key bits. The current experiment is a physical simulation of a true attack, because Eve has access to Bob's physical receiver module. This experiment illustrates the utility of an efficient deterministic quantum logic for performing realistic physical simulations of quantum information processing functions.Comment: 4 pages, 5 figure

    Evaluation of the National Compact – Aspirations and Impact

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    Compacts are written agreements that articulate the vision for cooperation between governments and the not-for-profit sector, generally with the overall aim of improving social outcomes. This report documents an evaluation which assessed the implementation and impact of Australia’s National Compact, and the extent to which it has contributed to improved relationships between Federal government agencies and the not-for-profit sector. Findings from interviews, focus groups and surveys captured the perspectives of leaders in the not-for-profit sector and staff in government agencies about the relationship between the sectors, and the role the Compact has played in improving this relationship. Government and not-for-profit stakeholders strongly value the sector relationship and perceive it to be improving, with two thirds of the respondents in the government survey and almost fifty percent in the not-for-profit survey characterising the relationship as strong. The Compact has formalised the importance of the relationship, raised expectations within government agencies and the not-for-profit sector and provided an important symbol and foundation for mutual commitment to improving the relationship. However, awareness of the Compact remains inconsistent; there is limited understanding of the way the Compact has underpinned important elements of not-for-profit reform; and many perceive Compact implementation has lost momentum. As a result, there is limited attribution of improvements in the sector relationship to the Compact. Australia has a critical need for a constructive government-not-for-profit partnership working towards more effective and efficient delivery of social outcomes. In the context of its ageing population and socio-demographic challenges, there will be significantly increasing pressure to deliver stronger outcomes with fewer resources. In this context, the Compact has a vital role to play. The evidence in this report suggests that to build on the Compact’s solid foundation and ensure long term impact, a renewed commitment is needed from leaders of the not-for-profit sector as well as bipartisan support from government. Action is needed to continue to build awareness of the Compact, its aims, actions and outcomes, and its achievements in articulating the foundations for not-for-profit reform. A clearer logic framework linking Compact aspirations to actions and outcomes is needed, to inform continued implementation across both sectors. Establishment of a monitoring framework and an annual Relationship Scorecard would drive on-going refinement of the implementation as well as increased awareness of and commitment to the Compact and its intended outcomes

    The association of long-term exposure to criteria air pollutants, fine particulate matter components, and airborne trace metals with late-life brain amyloid burden in the Atherosclerosis Risk in Communities (ARIC) study

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    BACKGROUND: Studies suggest associations between long-term ambient air pollution exposure and outcomes related to Alzheimer\u27s disease (AD). Whether a link exists between pollutants and brain amyloid accumulation, a biomarker of AD, is unclear. We assessed whether long-term air pollutant exposures are associated with late-life brain amyloid deposition in Atherosclerosis Risk in Communities (ARIC) study participants. METHODS: We used a chemical transport model with data fusion to estimate ambient concentrations of PM RESULTS: At PET imaging, eligible participants (N = 318) had a mean age of 78 years, 56% were female, 43% were Black, and 27% had mild cognitive impairment. We did not find evidence of associations between long-term exposure to any pollutant and brain amyloid positivity in adjusted models. Findings were materially unchanged in sensitivity analyses using alternate air pollution estimation approaches for PM CONCLUSIONS: Air pollution may impact cognition and dementia independent of amyloid accumulation, though whether air pollution influences AD pathogenesis later in the disease course or at higher exposure levels deserves further consideration

    Permutation asymmetry inducing entanglement between degrees of freedom in multiphoton states

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    We describe and examine entanglement between different degrees of freedom in multiphoton states based on the permutation properties. From the state description, the entanglement comes from the permutation asymmetry. According to the different permutation properties, the multiphoton states can be divided into several parts. It will help to deal with the multiphoton interference, which can be used as the measurement of the entanglement.Comment: Final versio

    Multi-technique characterisation of MOVPE-grown GaAs on Si

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    The heterogeneous integration of III-V materials on a Si CMOS platform offers tremendous prospects for future high speed and low power logic applications. That said this integration generates immense scientific and technological challenges. In this work multi-technique characterisation is used to investigate properties of GaAs layers grown by Metal-Organic Vapour Phase Epitaxy (MOVPE) on Si substrates - (100) with 4⁰ offset towards - under various growth conditions. This being a crucial first step towards the production of III-V template layers with a relatively lower density of defects for selective epitaxial overgrowth of device quality material. The optical and structural properties of heteroepitaxial GaAs are first investigated by micro-Raman spectroscopy and photoluminescence and reflectance measurements. High-resolution X-ray diffraction (HR-XRD) is used to investigate structural properties. Advanced XRD techniques, including double-axis diffraction and X-ray crystallographic mapping are used to evaluate degrees of relaxation and distribution of the grain orientations in the epilayers, respectively. Results obtained from the different methodologies are compared in an attempt to understand growth kinetics of the materials system. The GaAs overlayer grown with annealing at 735⁰C following As predeposition at 500⁰C shows the best crystallinity. Close inspection confirms the growth of epitaxial GaAs preferentially oriented along (100) embedded in a highly-textured polycrystalline structure

    Chemoenzymatic elaboration of monosaccharides using engineered cytochrome P450_(BM3) demethylases

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    Polysaccharides comprise an extremely important class of biopolymers that play critical roles in a wide range of biological processes, but the synthesis of these compounds is challenging because of their complex structures. We have developed a chemoenzymatic method for regioselective deprotection of monosaccharide substrates using engineered Bacillus megaterium cytochrome P450 (P450_(BM3)) demethylases that provides a highly efficient means to access valuable intermediates, which can be converted to a wide range of substituted monosaccharides and polysaccharides. Demethylases displaying high levels of regioselectivity toward a number of protected monosaccharides were identified using a combination of protein and substrate engineering, suggesting that this approach ultimately could be used in the synthesis of a wide range of substituted mono- and polysaccharides for studies in chemistry, biology, and medicine

    Probing nonstandard interactions with reactor neutrinos

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    New limits on the weak mixing angle and on the electron neutrino effective charge radius in the low energy regime, below 100 MeV, are obtained from a combined fit of all electron-(anti)neutrino electron elastic scattering measurements. We have included the recent TEXONO measurement with a CsI (Tl) detector. Only statistical error of this measurement has been taken into account. Weak mixing angle is found to be sin^2 theta_W = 0.255 +0.022 -0.023. The electron neutrino effective charge radius squared is bounded to be r^2 = (0.9 +0.9 -1.0) x 10^{-32} cm^2. The sensitivity of future low energy neutrino experiments to nonstandard interactions of neutrinos with quarks is also discussed.Comment: 3 pages, 2 figures, talk given at the Neutrino Oscillation Workshop (NOW 2008), Otranto, Italy, September 6-13, 2008. Misprints correcte

    Protecting Free-Living Dormice: Molecular Identification of Cestode Parasites in Captive Dormice (Muscardinus avellanarius) Destined for Reintroduction

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    The success of any population translocation programme relies heavily on the measures implemented to control and monitor the spread of disease. Without these measures, programmes run the risk of releasing immunologically naĂŻve species or, more dangerously, introducing novel infectious agents to native populations. As a precaution, a reintroduction programme for the common or hazel dormouse, Muscardinus avellanarius, in England screens dormice before release following captive breeding. Using PCR sequencing of a range of genes, we tested whether the same species of tapeworm(s) were present in captive and free-living dormice. Whilst only Rodentolepis straminea were identified in free-living dormice, cestode ova found in a captive individual produced a molecular match closely related to Hymenolepis microstoma and a previously unrecorded Rodentolepis species. To prevent putting at risk the free-living population, we recommended the continued treatment of dormice showing tapeworm infection before release. Our work demonstrates how molecular techniques can be used to inform reintroduction programmes, reduce risk from disease and increase chances of reintroduction success
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