701 research outputs found
The effect of a diet with fructan-rich chicory roots on intestinal helminths and microbiota with special focus on Bifidobacteria and Campylobacter in piglets around weaning
The restrictions on the use of antibiotic and anthelmintic treatments in organic pig farming necessitate alternative non-medical control strategies. Therefore, the antibiotic and parasite-reducing effect of a fructan-rich (prebiotic) diet of dried chicory was investigated in free-ranging piglets. Approximately half of 67 piglets from 9 litters were experimentally infected with Ascaris suum and Trichuris suis in the suckling period (1 to 7 weeks of age) and 58 of the piglets were challenged daily with E. coli O138:F8 for 9 days after weaning to induce weaning diarrhoea. The litters were fed either chicory (30% DM) or a control diet. The effect of chicory on intestinal helminths, intestinal microbiota, especially Bifidobacteria and Campylobacter spp., and E. coli post-weaning diarrhoea was assessed. The weight gain of the piglets was not impaired significantly by chicory. The intestinal A. suum worm burden was reduced by 64% (P=0.034) in the chicory-fed piglets, whereas these same piglets had 63% more T. suis worms (P=0.016). Feeding with chicory elicited no changes among the main bacterial groups in ileum according to terminal restriction fragment length polymorphism (T-RFLP) analysis. However, the terminal-restriction fragment (T-RF) 208 bp, which may belong to Lachnospiraceae, was stimulated by the chicory feed (P=0.03), and T-RF 370 bp that matches Enterobacter belonging to the Enterobacteria was reduced (P=0.004). Additionally, chicory increased the level of Bifidobacteria (P=0.001) and the faecal Campylobacter excretion level was transitorily reduced in chicory-fed piglets at 7 weeks of age (P=0.029). Unfortunately, it was not possible to assess the effect of chicory on post-weaning diarrhoea as it did not develop. In conclusion, feeding piglets chicory around the time of weaning caused complex changes of the microbiota and parasite communities within the intestinal tract, and feeding piglets chicory may therefore serve as an animal-friendly strategy to control pathogens
Path-decomposition expansion and edge effects in a confined magnetized free-electron gas
Path-integral methods can be used to derive a `path-decomposition expansion'
for the temperature Green function of a magnetized free-electron gas confined
by a hard wall. With the help of this expansion the asymptotic behaviour of the
profiles for the excess particle density and the electric current density far
from the edge is determined for arbitrary values of the magnetic field
strength. The asymptotics are found to depend sensitively on the degree of
degeneracy. For a non-degenerate electron gas the asymptotic profiles are
essentially Gaussian (albeit modulated by a Bessel function), on a length scale
that is a function of the magnetic field strength and the temperature. For a
completely degenerate electron gas the asymptotic behaviour is again
proportional to a Gaussian, with a scale that is the magnetic length in this
case. The prefactors are polynomial and logarithmic functions of the distance
from the wall, that depend on the number of filled Landau levels . As a
consequence, the Gaussian asymptotic decay sets in at distances that are large
compared to the magnetic length multiplied by .Comment: 16 pages, 2 figures, submitted to J. Phys. A: Math. Gen; corrected
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Complete quantization of a diffeomorphism invariant field theory
In order to test the canonical quantization programme for general relativity
we introduce a reduced model for a real sector of complexified Ashtekar gravity
which captures important properties of the full theory. While it does not
correspond to a subset of Einstein's gravity it has the advantage that the
programme of canonical quantization can be carried out completely and
explicitly, both, via the reduced phase space approach or along the lines of
the algebraic quantization programme. This model stands in close correspondence
to the frequently treated cylindrically symmetric waves. In contrast to other
models that have been looked at up to now in terms of the new variables the
reduced phase space is infinite dimensional while the scalar constraint is
genuinely bilinear in the momenta. The infinite number of Dirac observables can
be expressed in compact and explicit form in terms of the original phase space
variables. They turn out, as expected, to be non-local and form naturally a set
of countable cardinality.Comment: 32p, LATE
BioConcens: Biomass and bioenergy production agriculture – consequences for soil fertility, environment, spread of animal parasites and socio-economy
The research programme called “international research cooperation and organic integrity” was commenced for a period 2006-2010. It is coordinated by DARCOF (The Danish Research Centre for Organic Farming). The whole programme, with acronym DARCOF III, consists of 15 projects (http://www.darcof.dk/research/darcofiii/index.html). One of them is BIOCONCENS - Biomass and bioenergy production in organic farming – consequences for soil fertility, environment, spread of animal parasites and socio-economy (http://www.bioconcens.elr.dk/uk/). The production of bioenergy in organic agriculture (OA) can reduce its dependency of fossil fuels and decrease green house gasses emission; consequently it will increase sustainability of organic farms. Biorefinery concept based on co-production of biogas, bioethanol and protein fodder in organic farming will be developed within the BIOCONCENS project and the background for the project and the different work packages will be presented in this paper
Characterization of Serratia marcescens nuclease isoforms by plasma desorption mass spectrometry
Isoforms of Serratia marcescens nuclease found in the natural nuclease produced by S. marcescens and in recombinant nuclease produced by Escherichia coli were structurally characterized by peptide mapping using plasma desorption mass spectrometry. The nuclease isoforms produced and secreted from S. marcescens B10M1, which are present in much greater amounts than in S. marcescens W225 nuclease produced by E. coli, were characterized completely and the information used to facilitate characterization of the recombinant nuclease isoforms. After purification of the nuclease the isoforms were separated on a DEAE-cellulose anion-exchange column and then digested with endoproteinase Lys-C. The peptides generated were isolated by reverse-phase HPLC and their molecular masses determined by plasma desorption mass spectrometry. Comparison of the peptides from the native nuclease, Sm2, and the two isoforms, Sm1 and Sm3, revealed that they differed only in the N-terminus, the latter being found to lack three amino acids in Sm1 and one amino acid in Sm3. No interior post-translational changes were found in either of the three isoforms. Using this information we were able to confirm that Sm1, the isoform lacking three amino acids, was also present in very small amounts in recombinant S. marcescens W225 nuclease produced and excreted by E. coli. © 1993
Hot Electron Capture Dissociation Distinguishes Leucine from Isoleucine in a Novel Hemoglobin Variant, Hb Askew, β54(D5)Val→Ile
Population migration has led to the global dispersion of human hemoglobinopathies and has precipitated a need for their identification. An effective mass spectrometry-based procedure involves analysis of the intact α- and β-globin chains to determine their mass, followed by location of the variant amino acid residue by direct analysis of the enzymatically digested chains and low-energy collision induced dissociation of the variant peptide. Using this procedure, a variant was identified as either β54Val→Leu or β54Val→Ile, since the amino acids leucine and isoleucine cannot be distinguished using low-energy collisions. Here, we describe how hot electron capture dissociation on a Fourier transform-ion cyclotron resonance mass spectrometer was used to distinguish isoleucine from leucine and identify the mutation as β54(D5)Val→Ile. This is a novel variant, and we have named it Hb Askew
Relativistic diffusion processes and random walk models
The nonrelativistic standard model for a continuous, one-parameter diffusion
process in position space is the Wiener process. As well-known, the Gaussian
transition probability density function (PDF) of this process is in conflict
with special relativity, as it permits particles to propagate faster than the
speed of light. A frequently considered alternative is provided by the
telegraph equation, whose solutions avoid superluminal propagation speeds but
suffer from singular (non-continuous) diffusion fronts on the light cone, which
are unlikely to exist for massive particles. It is therefore advisable to
explore other alternatives as well. In this paper, a generalized Wiener process
is proposed that is continuous, avoids superluminal propagation, and reduces to
the standard Wiener process in the non-relativistic limit. The corresponding
relativistic diffusion propagator is obtained directly from the nonrelativistic
Wiener propagator, by rewriting the latter in terms of an integral over
actions. The resulting relativistic process is non-Markovian, in accordance
with the known fact that nontrivial continuous, relativistic Markov processes
in position space cannot exist. Hence, the proposed process defines a
consistent relativistic diffusion model for massive particles and provides a
viable alternative to the solutions of the telegraph equation.Comment: v3: final, shortened version to appear in Phys. Rev.
Performance and parasitosis in heifers grazing mixed with sows
Summary The aim of the study was to investigate the effect of mixed grazing with first season heifers and pregnant sows on animal performance, gastro-intestinal helminths, pasture quality and sward structure during three grazing seasons. This presentation will focus on results from 1999, primarily regarding performance and parasitosis in heifers. There have been no earlier reports on such mixed grazing systems. Three grazing systems were studied in replicate: 1) Heifers grazing alone; 2) sows grazing alone; 3) heifers grazing together with sows. The heifers were inoculated with low doses of infective O.ostertagi larvae at turn-out. Continuous grazing was practised in paddocks regulated in size according to herbage allowance. Individual weight gain, faecal egg output and serum pepsinogen concentrations -as indicator of O.ostertagi infection -were measured fortnightly. The sward structure and quality were greatly influenced by the applied grazing system. The average daily gain of the heifers was significantly higher (P=0.0006) when grazing together with sows (1,121±45 g/day, n=16) than when grazing alone (869±48 g/day, n=14). The mean pepsinogen concentrations were elevated in the heifers grazing alone. It is concluded, that weight gains were significantly better and infection levels with O.ostertagi were significantly reduced in heifers grazing together with sows. Introduction Outdoor pig production is increasing, especially in connection with organic farming. When sows with nose-ring graze alone, experience shows that the sward gets dirty and stemmy, and the sows destroy the sward in spots. It is well known that mixed grazing with sheep and cattle usually improves the utilization of the pasture and reduces parasite infectio
Guided random walk calculation of energies and <\sq {r^2} > values of the state of H_2 in a magnetic field
Energies and spatial observables for the state of the hydrogen
molecule in magnetic fields parallel to the proton-proton axis are calculated
with a guided random walk Feynman-Kac algorithm. We demonstrate that the
accuracy of the results and the simplicity of the method may prove it a viable
alternative to large basis set expansions for small molecules in applied
fields.Comment: 10 pages, no figure
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