19,798 research outputs found
Direct detection of Campylobacter from feces of organic and conventional pigs highlighted the presence of Campylobacter lanienae
In the frame of the CORE Organic II funded European project SafeOrganic, fecal samples from 31 organic pig herds and 31 conventional pig herds were sampled in a slaughterhouse. Samples were highly positive in Campylobacter coli but also in another Campylobacter species not described at that time in France.
Identification by MALDI-TOF mass spectrometry and PCR 16S allowed us to confirm that 85 isolates were C. Lanienae; 56 from conventional pigs and 29 from organic pigs. Individual occurrence in Campylobacter spp. was thus re-estimated to 91.1 % (51/56) and 96.3 % (52/54) for conventional and organic pigs, respectively. A total of 55 isolates of C. Lanienae were studied for their resistance to 7 antibiotics. Only one was pansusceptible. Natural resistance to Nalidixic acid was confirmed. Resistance to Tetracycline was significantly different (p \u3c to 0,001) between the two productions: 88 % of isolates from conventional pigs were resistant against 14% of isolates from organic pigs. Moreover, isolates from conventional pigs were mostly multiresistant (73%) whereas only 5% of strains isolated in organic pigs were multiresistant. The C. lanienae isolates were typed by PFGE using KpnI and SmaI enzymes. The genetic diversity was very high, whatever the enzyme used. No link between PFGE profile and isolate origin or antibiotic resistance pattern was evidenced. This study allowed us to demonstrate for the first time in France that pigs, known to be a reservoir for C. coli may also carry in their feces a species rarely highlighted: C. lanienae. The species was present in fecal samples from conventional and organic pigs. The lower level of antibiotic resistance and multiresistance of C. Lanienae strains for organic pigs may be related to the restricted use of antibiotics in this production
Parametrization of the angular correlation and degree of linear polarization in two-photon decays of hydrogen-like ions
The two-photon decay in hydrogen-like ions is investigated within the
framework of second order perturbation theory and Dirac's relativistic
equation. Special attention is paid to the angular correlation of the emitted
photons as well as to the degree of linear polarization of one of the two
photons, if the second is just observed under given angles. Expressions for the
angular correlation and the degree of linear polarization are expanded in terms
of -polynomials, whose coefficients depend on the atomic number and
the energy sharing of the emitted photons. The effects of including higher
(electric and magnetic) multipoles upon the emitted photon pairs beyond the
electric-dipole approximation are also discussed. Calculations of the
coefficients are performed for the transitions ,
and , along the
entire hydrogen isoelectronic sequence ()
Investigating parental care behaviour in same-sex pairing of zoo greater flamingo ( Phoenicopterus roseus )
This is the final version of the article. Available from PeerJ via the DOI in this record.Same-sex pair bonds have been documented in several animal species and they are widespread in birds. However, little is known about the evolutionary origin and the adaptive value of such behaviour. The aim of this study was to investigate the parental behaviour of four zoo female greater flamingos involved in two breeding pairs, housed in a flock at Parco Natura Viva, Italy. Further, the behaviour of the study females was compared with that of male and female flamingos in heterosexual pairs described in a previous published work on this same flock. For each pair, the behaviour of both birds during the incubation period was recorded and twenty 10-minute sessions were run within the incubation period. A continuous focal animal sampling method was used to collect data on location (on the nest or not on the nest) and the parental care behaviour (e.g.: agonistic behaviours toward disturbing conspecifics, egg-care, nest-building, self-comfort behaviour, sleeping) of the two pairs. Data of the current study females were compared with those of females and males involved in heterosexual pairs of this same flock. Results showed that within each pair the egg-layer female stayed away from the nest more than the other female. In addition, the female that did not lay an egg was more involved in agonistic behaviour compared to other females, particularly when in specific locations. In heterosexual pairs, male flamingos were more involved in the incubation and in nest protection. Moreover, no significant differences in the time spent on the nest and away from the nest between the heterosexual male and the non-layer females of same-sex pairs were found. The same findings were reported when comparing heterosexual females and the egg-layer females of the same-sex pairs. Therefore, our findings suggest that in greater flamingos the behaviour of the female–female pairs seems to be equivalent to that of male-female bonds. Such research provides more insight into flamingo social behaviour, and their reproductive cycle, and provides information on why pair bonds may form and how these affect the wider breeding behaviour of the flock
Comparison of organic and conventional pig productions on prevalence, antibiotic resistance and genetic diversity of Escherichia coli
The objectives of this study were to assess the prevalence, the tetracycline resistance level and the genetic diversity of Escherichia coli isolated from organic pigs in comparison with conventional pigs. This study is integrated in a global European project, Safeorganic, funded trough CORE Organic II call. 25 organic and 25 conventional herds were considered in one slaughterhouse from April to October 2012. Colon content of 2 pigs per herds was sampled. For each pig, enumeration of E. coli and of tetracycline resistant E. coli (TET+E. coli) was determined
Virtual light-by-light scattering and the g factor of a bound electron
The contribution of the light-by-light diagram to the g factor of electron
and muon bound in Coulomb field is obtained. For electron in a ground state,
our results are in good agreement with the results of other authors obtained
numerically for large Z. For relatively small Z our results have essentially
higher accuracy as compared to the previous ones. For muonic atoms, the
contribution is obtained for the first time with the high accuracy in whole
region of Z.Comment: 10 pages, 3 figures, RevTe
Structural and functional brain changes following four weeks of unimanual motor training: evidence from fMRI-guided diffusion MRI tractography
We have reported reliable changes in behaviour, brain structure and function in 24 healthy right-handed adults who practiced a finger-thumb opposition sequence task with their left hand for 10 mins daily, over four weeks. Here we extend these findings by employing diffusion MRI to investigate white-matter changes in the corticospinal tract, basal-ganglia, and connections of the dorsolateral prefrontal cortex. Twenty-three participant datasets were available with pre-training and post-training scans. Task performance improved in all participants (mean: 52.8%, SD: 20.0%; group
Relativistic total cross section and angular distribution for Rayleigh scattering by atomic hydrogen
We study the total cross section and angular distribution in Rayleigh
scattering by hydrogen atom in the ground state, within the framework of Dirac
relativistic equation and second-order perturbation theory. The relativistic
states used for the calculations are obtained by making use of the finite basis
set method and expressed in terms of B-splines and B-polynomials. We pay
particular attention to the effects that arise from higher (non-dipole) terms
in the expansion of the electron-photon interaction. It is shown that the
angular distribution of scattered photons, while it is symmetric with respect
to the scattering angle =90 within the electric dipole
approximation, becomes asymmetric when higher multipoles are taken into
account. The analytical expression of the angular distribution is parametrized
in terms of Legendre polynomials. Detailed calculations are performed for
photons in the energy range 0.5 to 10 keV. When possible, results are compared
with previous calculations.Comment: 8 pages, 5 figure
How much laser power can propagate through fusion plasma?
Propagation of intense laser beams is crucial for inertial confinement
fusion, which requires precise beam control to achieve the compression and
heating necessary to ignite the fusion reaction. The National Ignition Facility
(NIF), where fusion will be attempted, is now under construction. Control of
intense beam propagation may be ruined by laser beam self-focusing. We have
identified the maximum laser beam power that can propagate through fusion
plasma without significant self-focusing and have found excellent agreement
with recent experimental data, and suggest a way to increase that maximum by
appropriate choice of plasma composition with implication for NIF designs. Our
theory also leads to the prediction of anti-correlation between beam spray and
backscatter and suggests the indirect control of backscatter through
manipulation of plasma ionization state or acoustic damping.Comment: 15 pages, 4 figures, submitted to Plasma Physics and Controlled
Fusio
Angular distribution studies on the two-photon ionization of hydrogen-like ions: Relativistic description
The angular distribution of the emitted electrons, following the two-photon
ionization of the hydrogen-like ions, is studied within the framework of second
order perturbation theory and the Dirac equation. Using a density matrix
approach, we have investigated the effects which arise from the polarization of
the incoming light as well as from the higher multipoles in the expansion of
the electron--photon interaction. For medium- and high-Z ions, in particular,
the non-dipole contributions give rise to a significant change in the angular
distribution of the emitted electrons, if compared with the electric-dipole
approximation. This includes a strong forward emission while, in dipole
approxmation, the electron emission always occurs symmetric with respect to the
plane which is perpendicular to the photon beam. Detailed computations for the
dependence of the photoelectron angular distributions on the polarization of
the incident light are carried out for the ionization of H, Xe, and
U (hydrogen-like) ions.Comment: 16 pages, 4 figures, published in J Phys
Electric dipole-forbidden nuclear transitions driven by super-intense laser fields
Electric dipole-forbidden transitions of nuclei interacting with
super-intense laser fields are investigated considering stable isotopes with
suitable low-lying first excited states. Different classes of transitions are
identified, and all magnetic sublevels corresponding to the near-resonantly
driven nuclear transition are included in the description of the nuclear
quantum system. We find that large transition matrix elements and convenient
resonance energies qualify nuclear M1 transitions as good candidates for the
coherent driving of nuclei. We discuss the implications of resonant interaction
of intense laser fields with nuclei beyond the dipole approximation for the
controlled preparation of excited nuclear states and important aspects of
possible experiments aimed at observing these effects.Comment: 20 pages, 2 tables, 3 figures, minor modifications and update to the
published versio
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