9,544 research outputs found

    Analytic results for two-loop Yang-Mills

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    Recent Developments in computing very specific helicity amplitudes in two loop QCD are presented. The techniques focus upon the singular structure of the amplitude rather than on a diagramatic and integration approachComment: Talk presented at 13th International Symposium on Radiative Corrections, 24-29 September, 2017,St. Gilgen, Austria, 9 page

    The Primary Pretenders

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    We call a composite number q such that there exists a positive integer b with b^p == b (mod q) a prime pretender to base b. The least prime pretender to base b is the primary pretender q_b. It is shown that there are only 132 distinct primary pretenders, and that q_b is a periodic function of b whose period is the 122-digit number 19568584333460072587245340037736278982017213829337604336734362- 294738647777395483196097971852999259921329236506842360439300.Comment: 7 page

    Subscale, hydrogen-burning, airframe-integrated-scramjet: Experimental and theoretical evaluation of a water cooled strut airframe-integrated-scramjet: Experimental leading edge

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    A water-cooled leading-edge design for an engine/airframe integrated scramjet model strut leading edge was evaluated. The cooling design employs a copper cooling tube brazed just downstream of the leading edge of a wedge-shaped strut which is constructed of oxygen-free copper. The survival of the strut leading edge during a series of tests at stagnation point heating rates confirms the practicality of the cooling design. A finite difference thermal model of the strut was also proven valid by the reasonable agreement of calculated and measured values of surface temperature and cooling-water heat transfer

    Secure Borders and Uncertain Trade

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    Comparison Between Geese, Peking Ducks and Mallards in Ability to Digest Common Rye-Grass

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    The aim of this digestibility experiment was to observe the differences between geese, peking ducks and mallards to digest common ryegrass (Lolium perenne L.). Adult birds were used for the trials. The grass was frozen after harvesting, stored until the experimental period and fed in fresh constitution. The birds were reared in special single cages and had free access to water and grass. Geese have the best adapted digestive tract of all waterfowl species to consume and digest high-fibre feedstuffs. Peking ducks are able to consume a lot of grass and it seems the digestibility values are similar to geese. The acceptance of mallards for grass is low but the feed value appears not strongly different from geese and peking ducks

    A synthetic sample of short-cadence solar-like oscillators for TESS

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    NASA's Transiting Exoplanet Survey Satellite (TESS) has begun a two-year survey of most of the sky, which will include lightcurves for thousands of solar-like oscillators sampled at a cadence of two minutes. To prepare for this steady stream of data, we present a mock catalogue of lightcurves, designed to realistically mimic the properties of the TESS sample. In the process, we also present the first public release of the asteroFLAG Artificial Dataset Generator, which simulates lightcurves of solar-like oscillators based on input mode properties. The targets are drawn from a simulation of the Milky Way's populations and are selected in the same way as TESS's true Asteroseismic Target List. The lightcurves are produced by combining stellar models, pulsation calculations and semi-empirical models of solar-like oscillators. We describe the details of the catalogue and provide several examples. We provide pristine lightcurves to which noise can be added easily. This mock catalogue will be valuable in testing asteroseismology pipelines for TESS and our methods can be applied in preparation and planning for other observatories and observing campaigns.Comment: 14 pages, 6 figures, accepted for publication in ApJS. Archives containing the mock catalogue are available at https://doi.org/10.5281/zenodo.1470155 and the pipeline to produce it at https://github.com/warrickball/s4tess . The first public release of the asteroFLAG Artificial Dataset Generator v3 (AADG3) is described at https://warrickball.github.io/AADG3

    Integrating testing for sexually transmissible infections into routine primary care for Aboriginal young people: a strengths-based qualitative analysis

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    Objectives: This paper examines factors that enabled successful integration of testing for sexually transmissible infections into routine care in Aboriginal Community Controlled Health Services. Methods: This paper reports analysis of qualitative interview data recorded with 19 purposively sampled key informants in New South Wales, Australia, representing six Aboriginal Community Controlled Health Services and five government health bodies supporting those services. The analysis explicitly adopted a strengths-based approach. Results: Participants reported a strong belief that routine screening overcomes shame and increases engagement with sexual health screening. Incorporating sexual health screening into general medical consultations increases the capture of asymptomatic cases. The Medicare Benefits Schedule 715 Adult Health Check was highlighted as an ideal lever for effective integration into routine care. Conclusion: Integration of testing for sexually transmissible infections into routine care is widely perceived as best practice by senior stakeholders in Aboriginal healthcare in NSW. Findings support continued work to optimise the MBS 715 as a lever to increase testing. Implications for public health: Identifying accessible strategies to increase testing for sexually transmissible infections in Aboriginal Community Controlled Health Services can reduce disparities in notifications affecting Aboriginal young people

    Models of the Structure and Gating Mechanisms of the Pore Domain of the NaChBac Ion Channel

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    AbstractThe NaChBac prokaryotic sodium channel appears to be a descendent of an evolutionary link between voltage-gated KV and CaV channels. Like KV channels, four identical six-transmembrane subunits comprise the NaChBac channel, but its selectivity filter possesses a signature sequence of eukaryotic CaV channels. We developed structural models of the NaChBac channel in closed and open conformations, using K+-channel crystal structures as initial templates. Our models were also consistent with numerous experimental results and modeling criteria. This study concerns the pore domain. The major differences between our models and K+ crystal structures involve the latter portion of the selectivity filter and the bend region in S6 of the open conformation. These NaChBac models may serve as a stepping stone between K+ channels of known structure and NaV, CaV, and TRP channels of unknown structure

    Discovery of circularly polarised radio emission from SS 433

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    We report the discovery of circularly polarised radio emission from the radio-jet X-ray binary SS 433 with the Australia Telescope Compact Array. The flux density spectrum of the circular polarization, clearly detected at four frequencies between 1 - 9 GHz, has a spectral index of (-0.9 +/- 0.1). Multiple components in the source and a lack of very high spatial resolution do not allow a unique determination of the origin of the circular polarization, nor of the spectrum of fractional polarization. However, we argue that the emission is likely to arise in the inner regions of the binary, possibly via propagation-induced conversion of linear to circular polarization, and the fractional circular polarization of these regions may be as high as 10%. Observations such as these have the potential to investigate the composition, whether pairs or baryonic, of the ejecta from X-ray binaries.Comment: Accepted for publication in ApJ Letter

    Attractive instability of oppositely charged membranes induced by charge density fluctuations

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    We predict the conditions under which two oppositely charged membranes show a dynamic, attractive instability. Two layers with unequal charges of opposite sign can repel or be stable when in close proximity. However, dynamic charge density fluctuations can induce an attractive instability and thus facilitate fusion. We predict the dominant instability modes and timescales and show how these are controlled by the relative charge and membrane viscosities. These dynamic instabilities may be the precursors of membrane fusion in systems where artificial vesicles are engulfed by biological cells of opposite charge
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