3,447 research outputs found
Enzymes as Feed Additive to Aid in Responses Against Eimeria Species in Coccidia-Vaccinated Broilers Fed Corn-Soybean Meal Diets with Different Protein Levels
This research aimed to evaluate the effects of adding a combination of exogenous enzymes to starter diets varying in protein content and fed to broilers vaccinated at day of hatch with live oocysts and then challenged with mixed Eimeria spp. Five hundred four 1-d-old male Cobb-500 chickens were distributed in 72 cages. The design consisted of 12 treatments. Three anticoccidial control programs [ionophore (IO), coccidian vaccine (COV), and coccidia-vaccine + enzymes (COV + EC)] were evaluated under 3 CP levels (19, 21, and 23%), and 3 unmedicated-uninfected (UU) negative controls were included for each one of the protein levels. All chickens except those in unmedicated-uninfected negative controls were infected at 17 d of age with a mixed oral inoculum of Eimeria acervulina, Eimeria maxima, and Eimeria tenella. Live performance, lesion scores, oocyst counts, and samples for gut microflora profiles were evaluated 7 d postinfection. Ileal digestibility of amino acids (IDAA) was determined 8 d postinfection. Microbial communities (MC) were analyzed by G + C%, microbial numbers were counted by flow cytometry, and IgA concentrations were measured by ELISA. The lowest CP diets had poorer (P ≤ 0.001) BW gain and feed conversion ratio in the preinfection period. Coccidia-vaccinated broilers had lower performance than the ones fed ionophore diets during pre- and postchallenge periods. Intestinal lesion scores were affected (P ≤ 0.05) by anticoccidial control programs, but responses changed according to gut section. Feed additives or vaccination had no effect (P ≥ 0.05) on IDAA, and diets with 23% CP had the lowest (P ≤ 0.001) IDAA. Coccidial infection had no effect on MC numbers in the ileum but reduced MC numbers in ceca and suppressed ileal IgA production. The COV + EC treatment modulated MC during mixed coccidiosis infection but did not significantly improve chicken performance. Results indicated that feed enzymes may be used to modulate the gut microflora of cocci-vaccinated broiler chickens
Foundations Performance of Large Diameter Tanks
The paper presents a detailed case history of foundation performance of six 60-m diameter, 15-m high, floating roof fuel oil tanks and six 96.8-m diameter, 20-m high, fixed roof process water tanks built for a large power plant. Tank walls were supported by concrete ringwall footings. General subsurface conditions at the site are discussed, along with proposed site grading and the rationale for tank foundation selection. Because vibro-replacement improvement of site soils had been used beneath settlement-sensitive structures, there was skepticism regarding the decision to support the tanks on unimproved soils. To allay doubts about the adequacy of tank foundation performance, a staged hydrotesting procedure and an extensive settlement monitoring program were developed and implemented. The excellent tank hydrotesting results demonstrated that ground improvement was not needed due to the more settlement-tolerant nature of the tanks
Alterações bioquÃmicas em tilápias decorrentes da exposição a uma mistura de três herbicidas.
Resumo: O cultivo da cana de açúcar no Brasil utiliza grandes quantidades de herbicidas, o que constitui um sério risco para a biota aquática, se o manejo dos mesmos não for adequado. Uma prática comum é a aplicação de mistura de herbicidas. No presente trabalho avaliaram-se alterações da atividade de enzimas hepáticas de tilápias (Oreochromis niloticus) expostas em condições subletais a uma mistura diurom+hexazinona+tebutiurom. Mesmo em concentrações mais baixas das que manifestam efeitos agudos, enzimas antioxidantes e que auxiliam na eliminação do xenobióticos; Foram alteradas quanto ao seu padrão de normalidade. Os dados contribuem para o estabelecimento de concentrações máximas permissÃveis de herbicidas no compartimento aquático e na identificação de biomarcadores através de enzimas catalase, superoxido dismutase, glutationa-S-transferase e glutationa peroxidase e de exposição a esses poluentes
Dry matter production and nutrient extraction by three successive crops fertilized with serpentinite rock as a soil remineralizer.
The incorporation of new sources of fertilizers is important to of the food production security. The use of rock powders still needs investigation to address their agronomic efficiency and the safety for the users and for the consumers. This work aimed to study the dry matter production and the nutrient extraction after three consecutive crops, in two soils fertilized with serpentinite rock powder. The experiment was carried in a greenhouse, with three sequential crops, with seven treatments, two soils and four replications. After 40 days of growth, the whole plants were harvested and sent to measure the dry weight and for the chemical analyses. The use of the serpentinite did not increase the total dry matter biomass weight, compared to the fertilized controls. The magnesium extraction was not different between the control treatment with dolomitic limestone and the serpentinite treatment at higher dose for the clayed soil, indicating that the serpentinite was able to supply the magnesium for the plants in the experimental condition, and also a significant dose related effect suggests that the magnesium from the powder has been released. The use of the serpentinite also increased the extraction of other nutrients, like calcium, phosphorus, zinc and iron
Phase Transitions in Operational Risk
In this paper we explore the functional correlation approach to operational
risk. We consider networks with heterogeneous a-priori conditional and
unconditional failure probability. In the limit of sparse connectivity,
self-consistent expressions for the dynamical evolution of order parameters are
obtained. Under equilibrium conditions, expressions for the stationary states
are also obtained. The consequences of the analytical theory developed are
analyzed using phase diagrams. We find co-existence of operational and
non-operational phases, much as in liquid-gas systems. Such systems are
susceptible to discontinuous phase transitions from the operational to
non-operational phase via catastrophic breakdown. We find this feature to be
robust against variation of the microscopic modelling assumptions.Comment: 13 pages, 7 figures. Accepted in Physical Review
Proton and Helium Spectra from the CREAM-III Flight
Primary cosmic-ray elemental spectra have been measured with the
balloon-borne Cosmic Ray Energetics And Mass (CREAM) experiment since 2004. The
third CREAM payload (CREAM-III) flew for 29 days during the 2007-2008 Antarctic
season. Energies of incident particles above 1 TeV are measured with a
calorimeter. Individual elements are clearly separated with a charge resolution
of ~0.12 e (in charge units) and ~0.14 e for protons and helium nuclei,
respectively, using two layers of silicon charge detectors. The measured proton
and helium energy spectra at the top of the atmosphere are harder than other
existing measurements at a few tens of GeV. The relative abundance of protons
to helium nuclei is 9.53+-0.03 for the range of 1 TeV/n to 63 TeV/n. The ratio
is considerably smaller than other measurements at a few tens of GeV/n. The
spectra become softer above ~20 TeV. However, our statistical uncertainties are
large at these energies and more data are needed
Divergences in Kaluza-Klein Models and their String Regularization
Effective field theories with (large) extra dimensions are studied within a
physical regularization scheme provided by string theory. Explicit string
calculations then allow us to consistently analyze the ultraviolet sensitivity
of Kaluza--Klein theories in the presence or absence of low energy
supersymmetry.Comment: 50 pages, LaTe
Axisymmetric equilibria of a gravitating plasma with incompressible flows
It is found that the ideal magnetohydrodynamic equilibrium of an axisymmetric
gravitating magnetically confined plasma with incompressible flows is governed
by a second-order elliptic differential equation for the poloidal magnetic flux
function containing five flux functions coupled with a Poisson equation for the
gravitation potential, and an algebraic relation for the pressure. This set of
equations is amenable to analytic solutions. As an application, the
magnetic-dipole static axisymmetric equilibria with vanishing poloidal plasma
currents derived recently by Krasheninnikov, Catto, and Hazeltine [Phys. Rev.
Lett. {\bf 82}, 2689 (1999)] are extended to plasmas with finite poloidal
currents, subject to gravitating forces from a massive body (a star or black
hole) and inertial forces due to incompressible sheared flows. Explicit
solutions are obtained in two regimes: (a) in the low-energy regime
, where
, , , and are related to the thermal,
poloidal-current, flow and gravitating energies normalized to the
poloidal-magnetic-field energy, respectively, and (b) in the high-energy regime
. It turns out
that in the high-energy regime all four forces, pressure-gradient,
toroidal-magnetic-field, inertial, and gravitating contribute equally to the
formation of magnetic surfaces very extended and localized about the symmetry
plane such that the resulting equilibria resemble the accretion disks in
astrophysics.Comment: 12 pages, latex, to be published in Geophys. Astrophys. Fluid
Dynamic
Reduction Procedures in Classical and Quantum Mechanics
We present, in a pedagogical style, many instances of reduction procedures
appearing in a variety of physical situations, both classical and quantum. We
concentrate on the essential aspects of any reduction procedure, both in the
algebraic and geometrical setting, elucidating the analogies and the
differences between the classical and the quantum situations.Comment: AMS-LaTeX, 35 pages. Expanded version of the Invited review talk
delivered by G. Marmo at XXIst International Workshop On Differential
Geometric Methods In Theoretical Mechanics, Madrid (Spain), 2006. To appear
in Int. J. Geom. Methods in Modern Physic
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