1,297 research outputs found
Antimicrobial resistance in coagulase-positive staphylococci isolated from companion animals in Australia: a one year study
Published: April 21, 2017Methicillin-resistant coagulase-positive staphylococci (CoPS) have become increasingly recognised as opportunistic pathogens that limit therapeutic options in companion animals. The frequency of methicillin resistance amongst clinical isolates on an Australia-wide level is unknown. This study determined antimicrobial susceptibility patterns for CoPS isolated from clinical infections in companion animals (dogs, cats and horses) as part of the first nation-wide survey on antimicrobial resistance in animal pathogens in Australia for a one-year period (January 2013 to January 2014). Clinical Staphylococcus spp. isolates (n = 888) obtained from 22 veterinary diagnostic laboratories were identified by MALDI-TOF mass spectrometry and subjected to antimicrobial susceptibility testing for 16 antimicrobials, representing 12 antimicrobial classes. Potential risk factors associated with methicillin resistance in Staphylococcus pseudintermedius isolates from dogs were analysed based on demographic factors and clinical history, including gender, age, previous antimicrobial treatment, chronic and/or recurrent diseases and site of infections. The most commonly identified CoPS were S. pseudintermedius (70.8%; dogs n = 616, cats n = 13) and S. aureus (13.2%, horses n = 53, dogs n = 47 and cats n = 17). Overall, the frequency of methicillin resistance among S. pseudintermedius (MRSP) and S. aureus (MRSA) was 11.8% and 12.8%, respectively. MRSP isolates were strongly associated with resistance to fluoroquinolones (OR 287; 95%CI 91.2-1144.8) and clindamycin (OR 105.2, 95%CI 48.5-231.9). MRSA isolates from dogs and cats were also more likely to be resistant to fluoroquinolones (OR 5.4, 95%CI 0.6-252.1), whereas MRSA from horses were more likely to be resistant to rifampicin. In multivariate analysis, MRSP-positive status was significantly associated with particular infection sites, including surgical (OR 8.8; 95%CI 3.74-20.7), and skin and soft tissue (OR 3.9; 95%CI 1.97-7.51). S. pseudintermedius isolated from dogs with surgical site infections were three times more likely to be methicillin-resistant if cases had received prior antimicrobial treatment. Whilst the survey results indicate the proportion of CoPS obtained from Australian companion animals that are methicillin-resistant is currently moderate, the identified risk factors suggest that it could rapidly increase without adequate biosecurity and infection control procedures in veterinary practice.Sugiyono Saputra, David Jordan, Kate A. Worthing, Jacqueline M. Norris, Hui S. Wong, Rebecca Abraham, Darren J. Trott, Sam Abraha
Application of the Frobenius method to the Schrodinger equation for a spherically symmetric potential: anharmonic oscillator
The power series method has been adapted to compute the spectrum of the
Schrodinger equation for central potential of the form . The bound-state energies
are given as zeros of a calculable function, if the potential is confined in a
spherical box. For an unconfined potential the interval bounding the energy
eigenvalues can be determined in a similar way with an arbitrarily chosen
precision. The very accurate results for various spherically symmetric
anharmonic potentials are presented.Comment: 16 pages, 5 figures, published in J. Phys
Off-Critical Logarithmic Minimal Models
We consider the integrable minimal models , corresponding
to the perturbation off-criticality, in the {\it logarithmic
limit\,} , where are coprime and the
limit is taken through coprime values of . We view these off-critical
minimal models as the continuum scaling limit of the
Forrester-Baxter Restricted Solid-On-Solid (RSOS) models on the square lattice.
Applying Corner Transfer Matrices to the Forrester-Baxter RSOS models in Regime
III, we argue that taking first the thermodynamic limit and second the {\it
logarithmic limit\,} yields off-critical logarithmic minimal models corresponding to the perturbation of the critical
logarithmic minimal models . Specifically, in accord with the
Kyoto correspondence principle, we show that the logarithmic limit of the
one-dimensional configurational sums yields finitized quasi-rational characters
of the Kac representations of the critical logarithmic minimal models . We also calculate the logarithmic limit of certain off-critical
observables related to One Point Functions and show that the
associated critical exponents
produce all conformal dimensions in the infinitely extended Kac table. The corresponding Kac labels
satisfy . The exponent is obtained from the logarithmic limit of the free energy giving the
conformal dimension for the perturbing field . As befits a non-unitary
theory, some observables diverge at criticality.Comment: 18 pages, 5 figures; version 3 contains amplifications and minor
typographical correction
Genetic Diversity of PCR-Positive, Culture-Negative and Culture-Positive Mycobacterium ulcerans Isolated from Buruli Ulcer Patients in Ghana.
Culture of Mycobacterium ulcerans from Buruli ulcer patients has very low sensitivity. Thus confirmation of M. ulcerans infection is primarily based on PCR directed against IS2404. In this study we compare the genotypes obtained by variable number of tandem repeat analysis of DNA from IS2404-PCR positive cultures with that obtained from IS2404 positive, culture-negative tissue. A significantly greater genetic heterogeneity was found among culture-negative samples compared with that found in cultured strains but a single genotype is over-represented in both sample sets. This study provides evidence that both the focal location of bacteria in a lesion as well as differences in the ability to culture a particular genotype may underlie the low sensitivity of culture. Though preliminary, data from this work also suggests that mycobacteria previously associated with fish disease (M. pseudoshottsii) may be pathogenic for humans
Differential Microlensing Measurements of Quasar Broad Line Kinematics in Q2237+0305
The detailed workings of the central engines of powerful quasars remain a
mystery. This is primarily due to the fact that, at their cosmological
distances, the inner regions of these quasars are spatially unresolvable.
Reverberation mapping is now beginning to unlock the physics of the Broad
Emission Line Region (BELR) in nearby, low-luminosity quasars, however it is
still unknown whether this gas is dominated by virial motion, by outflows, or
infall. The challenge is greater for more distant, powerful sources due to the
very long response time of the BELR to changes in the continuum. We present a
new technique for probing the kinematic properties of the BELR and accretion
disk of high-z quasars using differential microlensing, and show how
substantial information can be gained through a single observation of a
strongly-lensed quasar using integral field spectroscopy. We apply this
technique to GMOS IFU observations of the multiply-imaged quasar Q2237+0305,
and find that the observed microlensing signature in the CIII] broad emission
line favours gravitationally-dominated dynamics over an accelerating outflow.Comment: 16 pages, 14 figure
R-parity preserving super-WIMP decays
We point out that when the decay of one electroweak scale super-WIMP state to
another occurs at second order in a super-weak coupling constant, this can
naturally lead to decay lifetimes that are much larger than the age of the
Universe, and create observable consequences for the indirect detection of dark
matter. We demonstrate this in a supersymmetric model with Dirac neutrinos,
where the right-handed scalar neutrinos are the lightest and next-to-lightest
supersymmetric partners. We show that this model produces a super-WIMP decay
rate scaling as m_nu^4/(weak scale)^3, and may significantly enhance the
fraction of energetic electrons and positrons over anti-protons in the decay
products. Such a signature is consistent with the observations recently
reported by the PAMELA experiment.Comment: 14 pages, v3 JHEP versio
The multiple quasar Q2237+0305 under a microlensing caustic
We use the high magnification event seen in the 1999 OGLE campaign light
curve of image C of the quadruply imaged gravitational lens Q2237+0305 to study
the structure of the quasar engine. We have obtained g'- and r'-band photometry
at the Apache Point Observatory 3.5m telescope where we find that the event has
a smaller amplitude in the r'-band than in the g'- and OGLE V-bands. By
comparing the light curves with microlensing simulations we obtain constraints
on the sizes of the quasar regions contributing to the g'- and r'-band flux.
Assuming that most of the surface mass density in the central kiloparsec of the
lensing galaxy is due to stars and by modeling the source with a Gaussian
profile, we obtain for the Gaussian width 1.20 x 10^15 sqrt(M/0.1M_sun)cm <
sigma_g' < 7.96 x 10^15 sqrt(M/0.1Msun) cm, where M is the mean microlensing
mass, and a ratio sigma_r'/sigma_g'=1.25^{+0.45}_{-0.15}. With the limits on
the velocity of the lensing galaxy from Gil-Merino et al. (2005) as our only
prior, we obtain 0.60 x 10^15 sqrt(M/0.1Msun) cm < sigma_g' < 1.57 x 10^15
sqrt(M/0.1Msun) cm and a ratio sigma_r'/sigma_g'=1.45^{+0.90}_{-0.25} (all
values at 68 percent confidence). Additionally, from our microlensing
simulations we find that, during the chromatic microlensing event observed, the
continuum emitting region of the quasar crossed a caustic at >72 percent
confidence.Comment: Accepted for publication in A&A, 8 pages, 4 figures. Slightly
modified compared to the original version: qualitative results unchanged,
constraints on the r'/g' source size ratio now tighter due to correction of
an error in the numerical treatment of the simulated light curve
Gridded and direct Epoch of Reionisation bispectrum estimates using the Murchison Widefield Array
We apply two methods to estimate the 21~cm bispectrum from data taken within
the Epoch of Reionisation (EoR) project of the Murchison Widefield Array (MWA).
Using data acquired with the Phase II compact array allows a direct bispectrum
estimate to be undertaken on the multiple redundantly-spaced triangles of
antenna tiles, as well as an estimate based on data gridded to the -plane.
The direct and gridded bispectrum estimators are applied to 21 hours of
high-band (167--197~MHz; =6.2--7.5) data from the 2016 and 2017 observing
seasons. Analytic predictions for the bispectrum bias and variance for point
source foregrounds are derived. We compare the output of these approaches, the
foreground contribution to the signal, and future prospects for measuring the
bispectra with redundant and non-redundant arrays. We find that some triangle
configurations yield bispectrum estimates that are consistent with the expected
noise level after 10 hours, while equilateral configurations are strongly
foreground-dominated. Careful choice of triangle configurations may be made to
reduce foreground bias that hinders power spectrum estimators, and the 21~cm
bispectrum may be accessible in less time than the 21~cm power spectrum for
some wave modes, with detections in hundreds of hours.Comment: 19 pages, 10 figures, accepted for publication in PAS
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