17,151 research outputs found
Campylobacter jejuni colonization promotes the translocation of Escherichia coli to extra-intestinal organs and disturbs the short-chain fatty acids profiles in the chicken gut
For a long time Campylobacter was only considered as a commensal microorganism in avian hosts restricted to the ceca, without any pathogenic features. The precise reasons for the symptomless chicken carriers are still unknown, but investigations of the gastrointestinal ecology of broiler chickens may improve our understanding of the microbial interactions with the host. Therefore, the current studies were conducted to investigate the effects of Campylobacter jejuni colonization on Escherichia coli translocation and on the metabolic end products (short-chain fatty acids, SCFAs). Following oral infection of 14 day old broiler chickens with 1 × 108 CFU of Campylobacter jejuni NCTC 12744 in two independent animal trials, it was found that C. jejuni heavily colonized the intestine and disseminate to extra-intestinal organs. Moreover, in both animal trials, the findings revealed that C. jejuni promoted the translocation of E. coli with a higher number encountered in the spleen and liver at 14 days post infection (dpi). In addition, Campylobacter affected the microbial fermentation in the gastrointestinal tract of broilers by reducing the amount of propionate, isovalerate, and isobutyrate in the cecal digesta of the infected birds at 2 dpi and, at 7 and 14 dpi, butyrate, isobutyrate, and isovalerate were also decreased. However, in the jejunum, the C. jejuni infection lowered only butyrate concentrations at 14 dpi. These data indicated that C. jejuni may utilize SCFAs as carbon sources to promote its colonization in the chicken gut, suggesting that Campylobacter cannot only alter gut colonization dynamics but might also influence physiological processes due to altered microbial metabolite profiles.
Finally, the results demonstrated that C. jejuni can cross the intestinal epithelial barrier and facilitates the translocation of Campylobacter itself as well as of other enteric microorganisms such as E. coli to extra-intestinal organs of infected birds. Altogether, our findings suggest that the Campylobacter carrier state in chicken is characterised by multiple changes in the intestinal barrier function, which supports multiplication and survival within the host
Synthesis, Characterization and Catalytic application of Barium modified Zirconia nanoparticle for the synthesis of â-Nitro alcohols
A series of barium modified zirconia nanoparticles were synthesized and evaluated for their catalytic activity for base catalyzed synthesis of â-nitro alcohol. The barium modified zirconia particles were synthesized by surface exchange reaction of zirconia with barium salt precursor. In order to study the effect of functionality and particle size of the zirconia particles on barium retention, zirconia samples were synthesized using five different methods namely combustion, amorphous citrate, precipitation, urea hydrolysis and evapouration induced self-assembly method. The zirconia samples contain both monoclinic and tetragonal phases. The relative content of the two phases depends strongly on the preparative procedure used. Highest tetragonal percentage was observed for the zirconia materials synthesized using amorphous citrate precursor route. The crystallite size of the synthesized zirconia was calculated using Fourier analysis of the broadened XRD profile of the zirconia samples. The urea hydrolysis method and the amorphous citrate methods are particularly effective for preparation of small nanosize zirconia particles. The XRD study of the Ba modified zirconia revealed the presence of barium zirconate and barium carbonate crystallographic phases along with the monoclinic and tetragonal form of zirconia. Growth of small particles over the surface of zirconia was observed in the barium modified sample from FESEM study. The barium modified zirconia particles were used as efficient base catalysts for synthesis of â-nitro alcohol by condensation of aryl aldehydes with nitromethane. The barium modified zirconia material was found to be active for the synthesis yielding a variety of â-nitro alcohol with good yield and purity
Possible Experience: from Boole to Bell
Mainstream interpretations of quantum theory maintain that violations of the
Bell inequalities deny at least either realism or Einstein locality. Here we
investigate the premises of the Bell-type inequalities by returning to earlier
inequalities presented by Boole and the findings of Vorob'ev as related to
these inequalities. These findings together with a space-time generalization of
Boole's elements of logic lead us to a completely transparent Einstein local
counterexample from everyday life that violates certain variations of the Bell
inequalities. We show that the counterexample suggests an interpretation of the
Born rule as a pre-measure of probability that can be transformed into a
Kolmogorov probability measure by certain Einstein local space-time
characterizations of the involved random variables.Comment: Published in: EPL, 87 (2009) 6000
Comment on "Exclusion of time in the theorem of Bell" by K. Hess and W. Philipp
A recent Letter by Hess and Philipp claims that Bell's theorem neglects the
possibility of time-like dependence in local hidden variables, hence is not
conclusive. Moreover the authors claim that they have constructed, in an
earlier paper, a local realistic model of the EPR correlations. However, they
themselves have neglected the experimenter's freedom to choose settings, while
on the other hand, Bell's theorem can be formulated to cope with time-like
dependence. This in itself proves that their toy model cannot satisfy local
realism, but we also indicate where their proof of its local realistic nature
fails.Comment: Latex needs epl.cl
Restricted Wiedemann-Franz law and vanishing thermoelectric power in one-dimensional conductors
In one-dimensional (1D) conductors with linear E-k dispersion (Dirac systems)
intrabranch thermalization is favored by elastic electron-electron interaction
in contrast to electron systems with a nonlinear (parabolic) dispersion. We
show that under external electric fields or thermal gradients the carrier
populations of different branches, treated as Fermi gases, have different
temperatures as a consequence of self-consistent carrier-heat transport.
Specifically, in the presence of elastic phonon scattering, the Wiedemann-Franz
law is restricted to each branch with its specific temperature and is
characterized by twice the Lorenz number. In addition thermoelectric power
vanishes due to electron-hole symmetry, which is validated by experiment.Comment: 10 pages, 2 figure
Recursiveness, Switching, and Fluctuations in a Replicating Catalytic Network
A protocell model consisting of mutually catalyzing molecules is studied in
order to investigate how chemical compositions are transferred recursively
through cell divisions under replication errors. Depending on the path rate,
the numbers of molecules and species, three phases are found: fast switching
state without recursive production, recursive production, and itinerancy
between the above two states. The number distributions of the molecules in the
recursive states are shown to be log-normal except for those species that form
a core hypercycle, and are explained with the help of a heuristic argument.Comment: 4 pages (with 7 figures (6 color)), submitted to PR
A Coupled Map Lattice Model for Rheological Chaos in Sheared Nematic Liquid Crystals
A variety of complex fluids under shear exhibit complex spatio-temporal
behaviour, including what is now termed rheological chaos, at moderate values
of the shear rate. Such chaos associated with rheological response occurs in
regimes where the Reynolds number is very small. It must thus arise as a
consequence of the coupling of the flow to internal structural variables
describing the local state of the fluid. We propose a coupled map lattice (CML)
model for such complex spatio-temporal behaviour in a passively sheared nematic
liquid crystal, using local maps constructed so as to accurately describe the
spatially homogeneous case. Such local maps are coupled diffusively to nearest
and next nearest neighbours to mimic the effects of spatial gradients in the
underlying equations of motion. We investigate the dynamical steady states
obtained as parameters in the map and the strength of the spatial coupling are
varied, studying local temporal properties at a single site as well as
spatio-temporal features of the extended system. Our methods reproduce the full
range of spatio-temporal behaviour seen in earlier one-dimensional studies
based on partial differential equations. We report results for both the one and
two-dimensional cases, showing that spatial coupling favours uniform or
periodically time-varying states, as intuitively expected. We demonstrate and
characterize regimes of spatio-temporal intermittency out of which chaos
develops. Our work suggests that such simplified lattice representations of the
spatio-temporal dynamics of complex fluids under shear may provide useful
insights as well as fast and numerically tractable alternatives to continuum
representations.Comment: 32 pages, single column, 20 figure
KAT-7 Science Verification: Using HI Observations of NGC 3109 to Understand its Kinematics and Mass Distribution
HI observations of the Magellanic-type spiral NGC 3109, obtained with the
seven dish Karoo Array Telescope (KAT-7), are used to analyze its mass
distribution. Our results are compared to what is obtained using VLA data.
KAT-7 is the precursor of the SKA pathfinder MeerKAT, which is under
construction. The short baselines and low system temperature of the telescope
make it sensitive to large scale low surface brightness emission. The new
observations with KAT-7 allow the measurement of the rotation curve of NGC 3109
out to 32', doubling the angular extent of existing measurements. A total HI
mass of 4.6 x 10^8 Msol is derived, 40% more than what was detected by the VLA
observations.
The observationally motivated pseudo-isothermal dark matter (DM) halo model
can reproduce very well the observed rotation curve but the cosmologically
motivated NFW DM model gives a much poorer fit to the data. While having a more
accurate gas distribution has reduced the discrepancy between the observed RC
and the MOdified Newtonian Dynamics (MOND) models, this is done at the expense
of having to use unrealistic mass-to-light ratios for the stellar disk and/or
very large values for the MOND universal constant a0. Different distances or HI
contents cannot reconcile MOND with the observed kinematics, in view of the
small errors on those two quantities. As for many slowly rotating gas-rich
galaxies studied recently, the present result for NGC 3109 continues to pose a
serious challenge to the MOND theory.Comment: 25 pages, 20 figures, accepted for publication in Astronomical
Journa
NMR relaxation time around a vortex in stripe superconductors
Site-dependent NMR relaxation time is calculated in the vortex
state using the Bogoliubov-de Gennes theory, taking account of possible
"field-induced stripe'' states in which the magnetism arises locally around a
vortex core in d-wave superconductivity. The recently observed huge enhancement
below at a core site in TlBaCuO is
explained. The field-induced stripe picture explains consistently other
relevant STM and neutron experiments.Comment: 4 pages, 4 figure
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