34,876 research outputs found
Intestinal Microbial Ecology of Broilers Vaccinated and Challenged With Mixed Eimeria Species, and Supplemented with Essential Oil Blends
Intestinal microbiota is an important component in the development of defense mechanisms in the gut mucosa. This project determined the dynamics of intestinal microbial communities (MC) of broilers vaccinated at first day of age with live oocysts of Eimeria species and fed diets supplemented with 2 specific essential oil (EO) blends, Crina Poultry (CP) and Crina Alternate (CA). Five treatments were analyzed: 1) unmedicated-uninfected (UU) control; 2) unmedicated-infected (UI) control; 3) vaccinated with Advent cocci-vaccine and without feed additive (COV) supplements; 4) vaccinated with Advent and supplemented with CP; and 5) vaccinated with Advent and supplemented with CA. The EO blends were added at 100 ppm to the same basal diets. Chicks were gavage-infected at 19 d of age with Eimeria acervulina, Eimeria maxima, and Eimeria tenella. Duodenal, ileal, and cecal samples were taken from 12 birds per treatment just before the infection and 7 d after the challenge, pooled in 6 samples, and frozen. Denaturing gradient gel electrophoresis was used to examine PCR-amplified fragments of the bacterial 16S ribosomal DNA variable region. Results are presented as percentages of similarity coefficients (SC). Dendrograms of amplicon patterns indicated MC differences due to intestinal location, feed additives, and cocci infection. The EO blends CP and CA did affect MC in all gut sections. The cocci-infection caused drastic MC population shifts in duodenal, ileal, and cecal sections (36.7, 55.4, and 36.2% SC, respectively). The CP-supplemented birds had higher SC between pre- and postchallenge MC in duodenal and ileal (73.3, 81.8%) than COV (66.4, 66.5%). However, COV broilers had the smallest changes in cecal MC after infection (79.5% SC). We concluded that cocci-vaccination causes small changes in intestinal MC, but challenge causes drastic shifts. The EO blend supplementation modulates MC in cocci-vaccinated broilers, avoiding drastic shifts after a mixed coccidia infection. Correlations between MC dynamics and host responses are discussed
Langlands duality for representations of quantum groups
We establish a correspondence (or duality) between the characters and the
crystal bases of finite-dimensional representations of quantum groups
associated to Langlands dual semi-simple Lie algebras. This duality may also be
stated purely in terms of semi-simple Lie algebras. To explain this duality, we
introduce an "interpolating quantum group" depending on two parameters which
interpolates between a quantum group and its Langlands dual. We construct
examples of its representations, depending on two parameters, which interpolate
between representations of two Langlands dual quantum groups.Comment: 37 pages. References added. Accepted for publication in Mathematische
Annale
What would you do? An investigation of stated-response data
When analysing choices or policy impacts, economists generally rely on what people actually do, rather than what they say they would do. The "stated response" approach is treated with scepticism due, for example, to concerns regarding the effect of strategic or social considerations on what people say, and a belief that people may not adequately consider such a hypothetical question. This paper evaluates an example of this approach; the direct questioning of parents as to whether they would withdraw their children from school if the Familias en Accion education subsidies were withdrawn. Our results suggest that these concerns are not entirely invalid but that the stated responses do provide important information and correlate in the expected manner with child and household characteristics. We conclude by emphasising the importance of good question design, which may allow researchers to use the "stated response" method as a complement to more typical quantitative methodologies
Two-dimensional Bloch electrons in perpendicular magnetic fields: an exact calculation of the Hofstadter butterfly spectrum
The problem of two-dimensional, independent electrons subject to a periodic
potential and a uniform perpendicular magnetic field unveils surprisingly rich
physics, as epitomized by the fractal energy spectrum known as Hofstadter's
Butterfly. It has hitherto been addressed using various approximations rooted
in either the strong potential or the strong field limiting cases. Here we
report calculations of the full spectrum of the single-particle Schr\"{o}dinger
equation without further approximations. Our method is exact, up to numerical
precision, for any combination of potential and uniform field strength. We
first study a situation that corresponds to the strong potential limit, and
compare the exact results to the predictions of a Hofstadter-like model. We
then go on to analyze the evolution of the fractal spectrum from a Landau-like
nearly-free electron system to the Hofstadter tight-binding limit by tuning the
amplitude of the modulation potential
Bound state of dimers on a spherical surface
The study of particle motion on spherical surfaces is relevant to adsorption
on buckyballs and other solid particles. This paper reports results for the
binding energy of such dimers, consisting of two light particles (He atoms or
hydrogen molecules) constrained to move on a spherical surface. The binding
energy reaches a particularly large value when the radius of the sphere is
about 3/4 of the particles' diameter.Comment: 6 pages, 3 figures, submitted to JLTP, conference proceedings QFS
200
Study of semileptonic and nonleptonic decays of the meson
We evaluate semileptonic and two--meson nonleptonic decays of the
meson in the framework of a nonrelativistic quark model. The former are done in
spectator approximation using one--body current operators at the quark level.
Our model reproduces the constraints of heavy quark spin symmetry obtained in
the limit of infinite heavy quark mass. For the two--meson nonleptonic decays
we work in factorization approximation. We compare our results to the ones
obtained in different relativistic approaches.Comment: Talk given at the IVth International Conference on Quarks an Nuclear
Physics, Madrid, June 5th-10th 200
Effects of Feed Additives and Mixed Eimeria Species Infection on Intestinal Microbial Ecology of Broilers
Evaluation of digestive microbial ecology is necessary to understand effects of growth-promoting feed. In the current study, the dynamics of intestinal microbial communities (MC) were examined in broilers fed diets supplemented with a combination of antibiotic (bacitracin methylene disalicylate) and ionophore (Coban 60), and diets containing 1 of 2 essential oil (EO) blends, Crina Poultry (CP) and Crina Alternate (CA). Five treatments were analyzed: 1) unmedicated uninfected control; 2) unmedicated infected control; 3) feed additives monensin (bacitracin methylene disalicylate) + monensin (Coban 60; AI); 4) EO blend CP; and 5) EO blend CA. Additives were mixed into a basal feed mixture, and EO were adjusted to 100 ppm. Chicks were infected by oral gavage at 19 d of age with Eimeria acervulina, Eimeria maxima, and Eimeria tenella. Duodenal, ileal, and cecal samples were taken from 12 birds per treatment just before and 7 d after challenge; 2 samples each were pooled to give a final number of 6 samples total; and all pooled samples were frozen until used for DNA extraction. Denaturing gradient gel electrophoresis was used to examine PCR-amplified fragments of the bacterial 16S ribosomal DNA variable region. Results are presented as percentages of similarity coefficients (SC). Dendrograms of PCR amplicon or band patterns indicated MC differences due to intestinal location, feed additives, and cocci challenge. Essential oil blends CP and CA affected MC in all gut sections. Each EO had different effects over MC, and they differed in most instances from the AI group. The cocci challenge caused drastic MC population shifts in duodenal, ileal, and cecal sections (36.7, 55.4, and 36.2% SC, respectively). Diets supplemented with CP supported higher SC between pre- and postchallenge MC (89.9, 83.3, and 76.4%) than AI (81.8., 57.4, and 60.0%). We concluded that mixed coccidia challenge caused drastic shifts in MC. These EO blends modulated MC better than AI, avoiding drastic shifts after a mixed challenge
Numerical Study of a Lyapunov Functional for the Complex Ginzburg-Landau Equation
We numerically study in the one-dimensional case the validity of the
functional calculated by Graham and coworkers as a Lyapunov potential for the
Complex Ginzburg-Landau equation. In non-chaotic regions of parameter space the
functional decreases monotonically in time towards the plane wave attractors,
as expected for a Lyapunov functional, provided that no phase singularities are
encountered. In the phase turbulence region the potential relaxes towards a
value characteristic of the phase turbulent attractor, and the dynamics there
approximately preserves a constant value. There are however very small but
systematic deviations from the theoretical predictions, that increase when
going deeper in the phase turbulence region. In more disordered chaotic regimes
characterized by the presence of phase singularities the functional is
ill-defined and then not a correct Lyapunov potential.Comment: 20 pages,LaTeX, Postcript version with figures included available at
http://formentor.uib.es/~montagne/textos/nep
Electromagnetic radiation produced by avalanches in the magnetization reversal of Mn12-Acetate
Electromagnetic radiation produced by avalanches in the magnetization
reversal of Mn12-Acetate has been measured. Short bursts of radiation have been
detected, with intensity significantly exceeding the intensity of the
black-body radiation from the sample. The model based upon superradiance from
inversely populated spin levels has been suggested
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