743 research outputs found

    Resolved photon and multi-component model for γ\gamma^*p and γγ\gamma^* \gamma^* scattering at high energies

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    We generalize our previous model for γp\gamma^* p scattering to γγ\gamma \gamma scattering. In the latter case the number of components naturally grows. When using the model parameters from our previous γp\gamma^* p analysis the model cross section for γγ\gamma \gamma scattering is larger than the corresponding LEP2 experimental data by more than a factor of two. However, performing a new simultaneous fit to γp\gamma^* p and γγ\gamma \gamma total cross section we can find an optimal set of parameters to describe both processes. We propose new measures of factorization breaking for γγ\gamma^* \gamma^* collisions and present results for our new model.Comment: 23 pages, 10 figure

    Microlensing Results Challenge the Core Accretion Runaway Growth Scenario for Gas Giants

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    We compare the planet-to-star mass-ratio distribution measured by gravitational microlensing to core accretion theory predictions from population synthesis models. The core accretion theory's runaway gas accretion process predicts a dearth of intermediate-mass giant planets that is not seen in the microlensing results. In particular, the models predict 10×\sim10\,\times fewer planets at mass ratios of 104q4×10410^{-4} \leq q \leq 4 \times 10^{-4} than inferred from microlensing observations. This tension implies that gas giant formation may involve processes that have hitherto been overlooked by existing core accretion models or that the planet-forming environment varies considerably as a function of host-star mass. Variation from the usual assumptions for the protoplanetary disk viscosity and thickness could reduce this discrepancy, but such changes might conflict with microlensing results at larger or smaller mass ratios, or with other observations. The resolution of this discrepancy may have important implications for planetary habitability because it has been suggested that the runaway gas accretion process may have triggered the delivery of water to our inner solar system. So, an understanding of giant planet formation may help us to determine the occurrence rate of habitable planets.Comment: 12 pages, 2 figures, 1 table, accepted for publication in ApJ

    European propolis is highly active against trypanosomatids including Crithidia fasciculata

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    Extracts of 35 samples of European propolis were tested against wild type and resistant strains of the protozoal pathogens Trypanosoma brucei, Trypanosoma congolense and Leishmania mexicana. The extracts were also tested against Crithidia fasciculata a close relative of Crithidia mellificae, a parasite of bees. Crithidia, Trypanosoma and Leishmania are all members of the order Kinetoplastida. High levels of activity were obtained for all the samples with the levels of activity varying across the sample set. The highest levels of activity were found against L. mexicana. The propolis samples were profiled by using liquid chromatography with high resolution mass spectrometry (LC-MS) and principal components analysis (PCA) of the data obtained indicated there was a wide variation in the composition of the propolis samples. Orthogonal partial least squares (OPLS) associated a butyrate ester of pinobanksin with high activity against T. brucei whereas in the case of T. congolense high activity was associated with methyl ethers of chrysin and pinobanksin. In the case of C. fasciculata highest activity was associated with methyl ethers of galangin and pinobanksin. OPLS modelling of the activities against L. mexicana using the mass spectrometry produced a less successful model suggesting a wider range of active components

    The evolution of tooth wear indices

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    Tooth wear—attrition, erosion and abrasion—is perceived internationally as an ever-increasing problem. Clinical and epidemiological studies, however, are difficult to interpret and compare due to differences in terminology and the large number of indices that have been developed for diagnosing, grading and monitoring dental hard tissue loss. These indices have been designed to identify increasing severity and are usually numerical. Some record lesions on an aetiological basis (e.g. erosion indices), others record lesions irrespective of aetiology (tooth wear indices); none have universal acceptance, complicating the evaluation of the true increase in prevalence reported. This article considers the ideal requirements for an erosion index. It reviews the literature to consider how current indices have evolved and discusses if these indices meet the clinical and research needs of the dental profession

    Pathological or physiological erosion—is there a relationship to age?

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    This conventional literature review discusses whether pathological tooth wear is age dependant. It briefly reviews the components of tooth wear and the prevalence of tooth wear in children, adolescents and adults. The emphasis on terminology relating to tooth wear varies. In some countries, the role of erosion is considered the most important, whereas others consider the process to be a combination of erosion, attrition and abrasion often with one being more dominant. The importance of tooth wear or erosion indices in the assessment and the evidence for progression within subject and within lesions is described. The data from the few studies reporting pathological levels of wear reported in children and adults are discussed, in particular its relationship with age. There is little evidence to support the concept that pathological levels of erosion or wear are age dependant. There is, however, some evidence to suggest that normal levels of erosion or wear are age dependant

    The First Neptune Analog or Super-Earth with Neptune-like Orbit: MOA-2013-BLG-605Lb

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    We present the discovery of the first Neptune analog exoplanet or super-Earth with Neptune-like orbit, MOA-2013-BLG-605Lb. This planet has a mass similar to that of Neptune or a super-Earth and it orbits at 9149\sim 14 times the expected position of the snow-line, asnowa_{\rm snow}, which is similar to Neptune's separation of 11asnow 11\,a_{\rm snow} from the Sun. The planet/host-star mass ratio is q=(3.6±0.7)×104q=(3.6\pm0.7)\times 10^{-4} and the projected separation normalized by the Einstein radius is s=2.39±0.05s=2.39\pm0.05. There are three degenerate physical solutions and two of these are due to a new type of degeneracy in the microlensing parallax parameters, which we designate "the wide degeneracy". The three models have (i) a Neptune-mass planet with a mass of Mp=217+6MEarthM_{\rm p}=21_{-7}^{+6} M_{Earth} orbiting a low-mass M-dwarf with a mass of Mh=0.190.06+0.05MM_{\rm h}=0.19_{-0.06}^{+0.05} M_\odot, (ii) a mini-Neptune with Mp=7.91.2+1.8MEarthM_{\rm p}= 7.9_{-1.2}^{+1.8} M_{Earth} orbiting a brown dwarf host with Mh=0.0680.011+0.019MM_{\rm h}=0.068_{-0.011}^{+0.019} M_\odot and (iii) a super-Earth with Mp=3.20.3+0.5MEarthM_{\rm p}= 3.2_{-0.3}^{+0.5} M_{Earth} orbiting a low-mass brown dwarf host with Mh=0.0250.004+0.005MM_{\rm h}=0.025_{-0.004}^{+0.005} M_\odot which is slightly favored. The 3-D planet-host separations are 4.61.2+4.7_{-1.2}^{+4.7} AU, 2.10.2+1.0_{-0.2}^{+1.0} AU and 0.940.02+0.67_{-0.02}^{+0.67} AU, which are 8.91.4+10.58.9_{-1.4}^{+10.5}, 121+712_{-1}^{+7} or 141+1114_{-1}^{+11} times larger than asnowa_{\rm snow} for these models, respectively. The Keck AO observation confirm that the lens is faint. This discovery suggests that low-mass planets with Neptune-like orbit are common. So processes similar to the one that formed Neptune in our own Solar System or cold super-Earth may be common in other solar systems.Comment: 54 pages, 10 figures, 13 tables, Accepted for publication in the Ap
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