16,003 research outputs found
Disinfection by hydrogen peroxide nebulization increases susceptibility to avian pathogenic Escherichia coli
Background: Avian pathogenic Escherichia coli (APEC) are the major cause of economic losses in the poultry industry worldwide. Traditionally, antibiotics are used to treat and prevent colibacillosis in broilers. Due to resistance development other ways of preventing/treating the disease have to be found. Therefore during this study the nebulization of low concentrations of hydrogen peroxide (H2O2) was tested in the presence of chickens to lower pathogenicity of APEC.
Results: Significantly higher total lesion scores and higher E. coli concentrations were found in the spleen of chickens exposed to 2 % H2O2 compared to those exposed to 1 % H2O2 and control chickens which had been exposed to nebulization with distilled water. Higher total lesions scores and E. coli concentrations in the spleen were found in chickens exposed to 1 % H2O2 in comparison to control chickens (not significant).
Conclusion: H2O2 is rendering animals more prone to APEC infection contraindicating H2O2 nebulization in the presence of chickens
How has the Louisiana Scholarship Program Affected Students? A Comprehensive Summary of Effects after Four Years
School choice has long been a subject of robust debate. Private school vouchers—programs providing public funds for students to attend K-12 private schools—tend to be the most contentious form of school choice. Over the past three years, our research team has released a series of reports examining how the LSP has affected key student and community conditions
The Effects of Gravitational Back-Reaction on Cosmological Perturbations
Because of the non-linearity of the Einstein equations, the cosmological
fluctuations which are generated during inflation on a wide range of
wavelengths do not evolve independently. In particular, to second order in
perturbation theory, the first order fluctuations back-react both on the
background geometry and on the perturbations themselves. I this paper, the
gravitational back-reaction of long wavelength (super-Hubble) scalar metric
fluctuations on the perturbations themselves is investigated for a large class
of inflationary models. Specifically, the equations describing the evolution of
long wavelength cosmological metric and matter perturbations in an inflationary
universe are solved to second order in both the amplitude of the perturbations
and in the slow roll expansion parameter. Assuming that the linear fluctuations
have random phases, we show that the fractional correction to the power
spectrum due to the leading infrared back-reaction terms does not change the
shape of the spectrum. The amplitude of the effect is suppressed by the product
of the inflationary slow-roll parameter and the amplitude of the linear power
spectrum. The non-gaussianity of the spectrum induced by back-reaction is
commented upon.Comment: 9 page
Transport phenomenology for a holon-spinon fluid
We propose that the normal-state transport in the cuprate superconductors can
be understood in terms of a two-fluid model of spinons and holons. In our
scenario, the resistivity is determined by the properties of the holons while
magnetotransport involves the recombination of holons and spinons to form
physical electrons. Our model implies that the Hall transport time is a measure
of the electron lifetime, which is shorter than the longitudinal transport
time. This agrees with our analysis of the normal-state data. We predict a
strong increase in linewidth with increasing temperature in photoemission. Our
model also suggests that the AC Hall effect is controlled by the transport
time.Comment: 4 pages, 1 postscript figure. Uses RevTeX, epsf, multico
TRADE LIBERALISATION UNDER THE DOHA DEVELOPMENT AGENDA; OPTIONS AND CONSEQUENCES FOR AFRICA
This study provides a quantitative estimate of the potential economic consequences of multilateral trade reform under the WTO for Africa using a framework that explicitly incorporates issues of concern to the region, such as preference erosion, loss of tariff revenue, and trade facilitation. It also examines the impact of OECD agricultural support programmes on economic welfare and specialisation in Africa. In the static version of the GTAP model, the study finds that full liberalisation of trade would increase global welfare (income) by 0.3 per cent, but would add 0.7 per cent annually to income in the African region. Sub-Saharan Africa and, to a lesser extent, Southern Africa, are vulnerable to partial trade reforms as they incur losses from partial reform while all other regions derive positive gains from a liberalisation of minor scope.International Relations/Trade,
Phenomenology of the Littlest Higgs with T-Parity
Little Higgs models offer an interesting approach to weakly coupled
electroweak symmetry breaking without fine tuning. The original little Higgs
models were plagued by strong constraints from electroweak precision data which
required a fine tuning to be reintroduced. An economical solution to this
problem is to introduce a discrete symmetry (analogous to R-parity of SUSY)
called T-parity. T-parity not only eliminates most constraints from electroweak
precision data, but it also leads to a promising dark matter candidate. In this
paper we investigate the dark matter candidate in the littlest Higgs model with
T-parity. We find bounds on the symmetry breaking scale f as a function of the
Higgs mass by calculating the relic density. We begin the study of the LHC
phenomenology of the littlest Higgs model with T-parity. We find that the model
offers an interesting collider signature that has a generic missing energy
signal which could "fake" SUSY at the LHC. We also investigate the properties
of the heavy partner of the top quark which is common to all littlest Higgs
models, and how its properties are modified with the introduction of T-parity.
We include an appendix with a list of Feynman rules specific to the littlest
Higgs with T-parity to facilitate further study.Comment: 32 pages, 8 figures; dark matter bounds revised; comphep model files
made publicly available at http://www.lns.cornell.edu/public/theory/tparity
Information Flow in Entangled Quantum Systems
All information in quantum systems is, notwithstanding Bell's theorem,
localised. Measuring or otherwise interacting with a quantum system S has no
effect on distant systems from which S is dynamically isolated, even if they
are entangled with S. Using the Heisenberg picture to analyse quantum
information processing makes this locality explicit, and reveals that under
some circumstances (in particular, in Einstein-Podolski-Rosen experiments and
in quantum teleportation) quantum information is transmitted through
'classical' (i.e. decoherent) information channels.Comment: PostScript version now available:
http://www.qubit.org/people/patrickh/Papers/InformationFlow.p
Analysis of Nonlinear Synchronization Dynamics of Oscillator Networks by Laplacian Spectral Methods
We analyze the synchronization dynamics of phase oscillators far from the
synchronization manifold, including the onset of synchronization on scale-free
networks with low and high clustering coefficients. We use normal coordinates
and corresponding time-averaged velocities derived from the Laplacian matrix,
which reflects the network's topology. In terms of these coordinates,
synchronization manifests itself as a contraction of the dynamics onto
progressively lower-dimensional submanifolds of phase space spanned by
Laplacian eigenvectors with lower eigenvalues. Differences between high and low
clustering networks can be correlated with features of the Laplacian spectrum.
For example, the inhibition of full synchoronization at high clustering is
associated with a group of low-lying modes that fail to lock even at strong
coupling, while the advanced partial synchronizationat low coupling noted
elsewhere is associated with high-eigenvalue modes.Comment: Revised version: References added, introduction rewritten, additional
minor changes for clarit
Diffusion of a granular pulse in a rotating drum
The diffusion of a pulse of small grains in an horizontal rotating drum is
studied through discrete elements methods simulations. We present a theoretical
analysis of the diffusion process in a one-dimensional confined space in order
to elucidate the effect of the confining end-plate of the drum. We then show
that the diffusion is neither subdiffusive nor superdiffusive but normal. This
is demonstrated by rescaling the concentration profiles obtained at various
stages and by studying the time evolution of the mean squared deviation.
Finally we study the self-diffusion of both large and small grains and we show
that it is normal and that the diffusion coefficient is independent of the
grain size
The decay b -> s g at NLL in the Standard Model
I present the Standard Model calculation of the decay rate for b -> s g (g
denotes a gluon) at next-to-leading logarithms (NLL). In order to get a
meaningful physical result, the decay b -> s g g and certain contributions of b
-> s \bar{f} f (where f are the light quark flavours u, d and s) have to be
included as well. Numerically we get BR^(NLL) = (5.0 +/- 1.0) * 10^{-3} which
is more than a factor 2 larger than the leading logarithmic result BR^(LL) =
(2.2 +/- 0.8) * 10^{-3}. Further, I consider the impact of this contribution on
the charmless hadronic branching ratio BRc, which could be used to extract the
CKM-ratio |V_(ub)/V_(cb)| with more accuracy. Finally, I have a short look at
BRc in scenarios where the Wilson coefficient C_8 is enhanced by new physics.Comment: 7 pages including 5 postscript figures; uses epsfi
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