388 research outputs found
Novel hemotropic mycoplasmas are widespread and genetically diverse in vampire bats
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
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
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
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
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
Additivity of Breit-Wigner phases has been proposed to describe interfering
resonances in partial waves in 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
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 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
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
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
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
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 . 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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