2,145 research outputs found

    The XO Planetary Survey Project - Astrophysical False Positives

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    Searches for planetary transits find many astrophysical false positives as a by-product. There are four main types analyzed in the literature: a grazing-incidence eclipsing binary star, an eclipsing binary star with a small radius companion star, a blend of one or more stars with an unrelated eclipsing binary star, and a physical triple star system. We present a list of 69 astrophysical false positives that had been identified as candidates of transiting planets of the on-going XO survey. This list may be useful in order to avoid redundant observation and characterization of these particular candidates independently identified by other wide-field searches for transiting planets. The list may be useful for those modeling the yield of the XO survey and surveys similar to it. Subsequent observations of some of the listed stars may improve mass-radius relations, especially for low-mass stars. From the candidates exhibiting eclipses, we report three new spectroscopic double-line binaries and give mass function estimations for 15 single lined spectroscopic binaries.Comment: 13 pages, 4 figures, accepted to ApJ

    An analysis of the feasibility of using image processing to estimate the live weight of sheep

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    One of the difficulties in successfully managing the supply and use of animal feed in sheep farming is in knowing the live weight of the sheep in the various mobs a farmer may be using. Most farmers make intuitive estimates of whether their sheep are increasing, maintaining or losing weight. A few farmers will weigh samples from the mobs, but this is an expensive and tedious operation, and consequently not carried out very often. If an inexpensive and simple method could be devised for quickly obtaining the average live weight of a mob of sheep this would markedly aid their successful management. This discussion paper contains outlines of the various methods that might be used as well as the problems with each method. There are also discussions covering the efforts made, as explained in the literature, for use in estimating the live weight of other species. This provides a means of generating ideas. The discussion paper concludes with recommendations on what appear to be the most promising approaches that might be further investigated. If such a system could be devised there is no doubt many farmers around the world would utilise it to assist in the management of their feed supplies, and consequently improve the efficient production of meat and wool

    Electron rescattering at metal nanotips induced by ultrashort laser pulses

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    We report on the first investigation of plateau and cut-off structures in photoelectron spectra from nano-scale metal tips interacting with few-cycle near-infrared laser pulses. These hallmarks of electron rescattering, well-known from atom-laser interaction in the strong-field regime, appear at remarkably low laser intensities with nominal Keldysh parameters of the order of ≳10\gtrsim 10. Quantum and quasi-classical simulations reveal that a large field enhancement near the tip and the increased backscattering probability at a solid-state target play a key role. Plateau electrons are by an order of magnitude more abundant than in comparable atomic spectra, reflecting the high density of target atoms at the surface. The position of the cut-off serves as an in-situ probe for the locally enhanced electric field at the tip apex

    Bushmeat Hunting, Deforestation, and Prediction of Zoonotic Disease

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    Integrating virology, ecology, and other disciplines enhances prediction of new emerging zoonoses

    Biliary Duct Granular Cell Tumor: A Rare But Surgically Curable Benign Tumor

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    Granulosa cell tumors are rare benign tumors which may be found throughout the body. Rare cases are isolated within the biliary tree. If completely resected, surgical excision is curative

    Microwave Spectroscopy

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    Contains reports on five research projects

    X-irradiation of cells on glass slides has a dose doubling impact

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    Immunofluorescence detection of γH2AX foci is a widely used tool to quantify the induction and repair of DNA double-strand breaks (DSBs) induced by ionising radiation. We observed that X-irradiation of mammalian cells exposed on glass slides induced twofold higher foci numbers compared to irradiation with γ-rays. Here, we show that the excess γH2AX foci after X-irradiation are produced from secondary radiation particles generated from the irradiation of glass slides. Both 120 kV X-rays and 137Cs γ-rays induce ∼20 γH2AX foci per Gy in cells growing on thin (∼2 μm) plastic foils immersed in water. The same yield is obtained following γ-irradiation of cells growing on glass slides. However, 120 kV X-rays produce ∼40 γH2AX foci per Gy in cells growing on glass, twofold greater than obtained using cells irradiated on plastic surfaces. The same increase in γH2AX foci number is obtained if the plastic foil on which the cells are grown is irradiated on a glass slide. Thus, the physical proximity to the glass material and not morphological differences of cells growing on different surfaces accounts for the excess γH2AX foci. The increase in foci number depends on the energy and is considerably smaller for 25 kV relative to 120 kV X-rays, a finding which can be explained by known physical properties of radiation. The kinetics for the loss of foci, which is taken to represent the rate of DSB repair, as well as the Artemis dependent repair fraction, was similar following X- or γ-irradiation, demonstrating that DSBs induced by this range of treatments are repaired in an identical manner

    Antimicrobial treatment improves mycobacterial survival in nonpermissive growth conditions

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    Antimicrobials targeting cell wall biosynthesis are generally considered inactive against nonreplicating bacteria. Paradoxically, we found that under nonpermissive growth conditions, exposure of Mycobacterium bovis BCG bacilli to such antimicrobials enhanced their survival. We identified a transcriptional regulator, RaaS (for regulator of antimicrobial-assisted survival), encoded by bcg1279 (rv1219c) as being responsible for the observed phenomenon. Induction of this transcriptional regulator resulted in reduced expression of specific ATP-dependent efflux pumps and promoted long-term survival of mycobacteria, while its deletion accelerated bacterial death under nonpermissive growth conditions in vitro and during macrophage or mouse infection. These findings have implications for the design of antimicrobial drug combination therapies for persistent infectious diseases, such as tuberculosis
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