378 research outputs found

    Novel hemotropic mycoplasmas are widespread and genetically diverse in vampire bats

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    Bats (Order: Chiroptera) have been widely studied as reservoir hosts for viruses of concern for human and animal health. However, whether bats are equally competent hosts of non-viral pathogens such as bacteria remains an important open question. Here, we surveyed blood and saliva samples of vampire bats from Peru and Belize for hemotropic Mycoplasma spp. (hemoplasmas), bacteria that can cause inapparent infection or anemia in hosts. 16S rRNA gene amplification of blood showed 67% (150/223) of common vampire bats (Desmodus rotundus) were infected by hemoplasmas. Sequencing of the 16S rRNA gene amplicons revealed three novel genotypes that were phylogenetically related but not identical to hemoplasmas described from other (non-vampire) bat species, rodents, humans, and non-human primates. Hemoplasma prevalence in vampire bats was highest in non-reproductive and young individuals, did not differ by country, and was relatively stable over time (i.e., endemic). Metagenomics from pooled D. rotundus saliva from Peru detected non-hemotropic Mycoplasma species and hemoplasma genotypes phylogenetically similar to those identified in blood, providing indirect evidence for potential direct transmission of hemoplasmas through biting or social contacts. This study demonstrates vampire bats host several novel hemoplasmas and sheds light on risk factors for infection and basic transmission routes. Given the high frequency of direct contacts that arise when vampire bats feed on humans, domestic animals, and wildlife, the potential of these bacteria to be transmitted between species should be investigated in future work

    Worldwide occurrence of haemoplasmas in wildlife: Insights into the patterns of infection, transmission, pathology and zoonotic potential

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    Haemotropic mycoplasmas (haemoplasmas) have increasingly attracted the attention of wildlife disease researchers due to a combination of wide host range, high prevalence and genetic diversity. A systematic review identified 75 articles that investigated haemoplasma infection in wildlife by molecular methods (chiefly targeting partial 16S rRNA gene sequences), which included 131 host genera across six orders. Studies were less common in the Eastern Hemisphere (especially Africa and Asia) and more frequent in the Artiodactyla and Carnivora. Meta-analysis showed that infection prevalence did not vary by geographic region nor host order, but wild hosts showed significantly higher prevalence than captive hosts. Using a taxonomically flexible machine learning algorithm, we also found vampire bats and cervids to have greater prevalence, whereas mink, a subclade of vesper bats, and true foxes all had lower prevalence compared to the remaining sampled mammal phylogeny. Haemoplasma genotype and nucleotide diversity varied little among wild mammals but were marginally lower in primates and bats. Coinfection with more than one haemoplasma species or genotype was always confirmed when assessed. Risk factors of infection identified were sociality, age, males and high trophic levels, and both prevalence and diversity were often higher in undisturbed environments. Haemoplasmas likely use different and concurrent transmission routes and typically display enzootic dynamics when wild populations are studied longitudinally. Haemoplasma pathology is poorly known in wildlife but appears subclinical. Candidatus Mycoplasma haematohominis, which causes disease in humans, probably has it natural host in bats. Haemoplasmas can serve as a model system in ecological and evolutionary studies, and future research on these pathogens in wildlife must focus on increasing the geographic range and taxa of studies and elucidating pathology, transmission and zoonotic potential. To facilitate such work, we recommend using universal PCR primers or NGS protocols to detect novel haemoplasmas and other genetic markers to differentiate among species and infer cross-species transmission

    Width of Sunspot Generating Zone and Reconstruction of Butterfly Diagram

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    Based on the extended Greenwich-NOAA/USAF catalogue of sunspot groups it is demonstrated that the parameters describing the latitudinal width of the sunspot generating zone (SGZ) are closely related to the current level of solar activity, and the growth of the activity leads to the expansion of SGZ. The ratio of the sunspot number to the width of SGZ shows saturation at a certain level of the sunspot number, and above this level the increase of the activity takes place mostly due to the expansion of SGZ. It is shown that the mean latitudes of sunspots can be reconstructed from the amplitudes of solar activity. Using the obtained relations and the group sunspot numbers by Hoyt and Schatten (1998), the latitude distribution of sunspot groups ("the Maunder butterfly diagram") for the 18th and the first half of the 19th centuries is reconstructed and compared with historical sunspot observations.Comment: 16 pages, 11 figures; accepted by Solar Physics; the final publication will be available at www.springerlink.co

    New study of the isotensor pi-pi interaction

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    With t-channel rho, f2(1270) exchange and the pi pi -> rho rho -> pi pi box diagram contribution, we reproduce the pi pi isotensor S-wave and D-wave scattering phase shifts and inelasticities up to 2.2 GeV quite well in a K-matrix formalism. The t-channel rho exchange provides repulsive negative phase shifts while the t-channel f2(1270) gives an attractive force to increase the phase shifts for pi pi scattering above 1 GeV, and the coupled-channel box diagram causes the inelasticities. The implication to the isoscalar pi pi S-wave interaction is discussed.Comment: 17 pages, 5 figure

    Brane Inflation, Solitons and Cosmological Solutions: I

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    In this paper we study various cosmological solutions for a D3/D7 system directly from M-theory with fluxes and M2-branes. In M-theory, these solutions exist only if we incorporate higher derivative corrections from the curvatures as well as G-fluxes. We take these corrections into account and study a number of toy cosmologies, including one with a novel background for the D3/D7 system whose supergravity solution can be completely determined. This new background preserves all the good properties of the original model and opens up avenues to investigate cosmological effects from wrapped branes and brane-antibrane annihilation, to name a few. We also discuss in some detail semilocal defects with higher global symmetries, for example exceptional ones, that could occur in a slightly different regime of our D3/D7 model. We show that the D3/D7 system does have the required ingredients to realise these configurations as non-topological solitons of the theory. These constructions also allow us to give a physical meaning to the existence of certain underlying homogeneous quaternionic Kahler manifolds.Comment: Harvmac, 115 pages, 9 .eps figures; v2: typos corrected, references added and the last section expanded; v3: Few minor typos corrected and references added. Final version to appear in JHE

    Unitarity and Interfering Resonances in pipi Scattering and in Pion Production piN->pipiN

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    Additivity of Breit-Wigner phases has been proposed to describe interfering resonances in partial waves in ππ\pi\pi scattering. This assumption leads to an expression for partial wave amplitudes that involves products of Breit-Wigner amplitudes. We show that this expression is equivalent to a coherent sum of Breit-Wigner amplitudes with specific complex coefficients which depend on the resonance parameters of all contributing resonances. We use analyticity of ππ\pi\pi partial wave amplitudes to show that they must have the form of a coherent sum of Breit-Wigner amplitudes with complex coefficients and a complex coherent background. The assumption of additivity of Breit-Wigner phases restricts the partial waves to analytical functions with very specific form of residues of Breit-Wigner poles. We argue that the general form provided by the analyticity is more appropriate in fits to data to determine resonance parameters. The partial wave unitarity can be imposed using the modern methods of constrained optimization. We discuss unitarity and the production amplitudes in πNππN\pi N\to\pi\pi N and use analyticity in the dipion mass variable to justify the common practice of writing the production amplitudes as a coherent sum of Breit-Wigner amplitudes with free complex coefficients and a complex coherent background in fits to mass spectra with interfering resonances.Comment: 31 page

    Probing quantum gravity using photons from a flare of the active galactic nucleus Markarian 501 observed by the MAGIC telescope

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    We analyze the timing of photons observed by the MAGIC telescope during a flare of the active galactic nucleus Mkn 501 for a possible correlation with energy, as suggested by some models of quantum gravity (QG), which predict a vacuum refractive index \simeq 1 + (E/M_{QGn})^n, n = 1,2. Parametrizing the delay between gamma-rays of different energies as \Delta t =\pm\tau_l E or \Delta t =\pm\tau_q E^2, we find \tau_l=(0.030\pm0.012) s/GeV at the 2.5-sigma level, and \tau_q=(3.71\pm2.57)x10^{-6} s/GeV^2, respectively. We use these results to establish lower limits M_{QG1} > 0.21x10^{18} GeV and M_{QG2} > 0.26x10^{11} GeV at the 95% C.L. Monte Carlo studies confirm the MAGIC sensitivity to propagation effects at these levels. Thermal plasma effects in the source are negligible, but we cannot exclude the importance of some other source effect.Comment: 12 pages, 3 figures, Phys. Lett. B, reflects published versio

    The Deuteron Spin-dependent Structure Function g1d and its First Moment

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    We present a measurement of the deuteron spin-dependent structure function g1d based on the data collected by the COMPASS experiment at CERN during the years 2002-2004. The data provide an accurate evaluation for Gamma_1^d, the first moment of g1d(x), and for the matrix element of the singlet axial current, a0. The results of QCD fits in the next to leading order (NLO) on all g1 deep inelastic scattering data are also presented. They provide two solutions with the gluon spin distribution function Delta G positive or negative, which describe the data equally well. In both cases, at Q^2 = 3 (GeV/c)^2 the first moment of Delta G is found to be of the order of 0.2 - 0.3 in absolute value.Comment: fits redone using MRST2004 instead of MRSV1998 for G(x), correlation matrix adde

    A new measurement of the Collins and Sivers asymmetries on a transversely polarised deuteron target

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    New high precision measurements of the Collins and Sivers asymmetries of charged hadrons produced in deep-inelastic scattering of muons on a transversely polarised 6LiD target are presented. The data were taken in 2003 and 2004 with the COMPASS spectrometer using the muon beam of the CERN SPS at 160 GeV/c. Both the Collins and Sivers asymmetries turn out to be compatible with zero, within the present statistical errors, which are more than a factor of 2 smaller than those of the published COMPASS results from the 2002 data. The final results from the 2002, 2003 and 2004 runs are compared with naive expectations and with existing model calculations.Comment: 40 pages, 28 figure

    Anisotropy studies around the galactic centre at EeV energies with the Auger Observatory

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    Data from the Pierre Auger Observatory are analyzed to search for anisotropies near the direction of the Galactic Centre at EeV energies. The exposure of the surface array in this part of the sky is already significantly larger than that of the fore-runner experiments. Our results do not support previous findings of localized excesses in the AGASA and SUGAR data. We set an upper bound on a point-like flux of cosmic rays arriving from the Galactic Centre which excludes several scenarios predicting sources of EeV neutrons from Sagittarius AA. Also the events detected simultaneously by the surface and fluorescence detectors (the `hybrid' data set), which have better pointing accuracy but are less numerous than those of the surface array alone, do not show any significant localized excess from this direction.Comment: Matches published versio
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