46 research outputs found
Hartree-Fock-Bogoliubov Calculations of the Rotational Band of the Very Heavy No Nucleus
We report on Hartree-Fock-Bogoliubov (HFB) calculations of the ground-state
rotationnal band of the heavy nucleus No recently observed
experimentally. The calculated quadrupole deformation is consistent with the
experimental value of and is almost constant over the whole band.
We also reproduce fairly well the excitation spectra and moments of inertia of
this isotope up to the maximal experimentally observed state of spin 20. The
rather high stability of this nucleus against fission is illustrated by the
deformation energy curve providing very high fission barriers at zero spin
within the HFB and HFB plus Lipkin-Nogami formalisms. The variation of these
barriers with increased angular velocities is also studied.Comment: 4 pages (LaTeX), submitted to Eur. Phys. J A, dedicated to the memory
of J. Piperov
Strongly damped nuclear collisions: zero or first sound ?
The relaxation of the collective quadrupole motion in the initial stage of a
central heavy ion collision at beam energies AMeV is studied
within a microscopic kinetic transport model. The damping rate is shown to be a
non-monotonic function of E_{lab} for a given pair of colliding nuclei. This
fact is interpreted as a manifestation of the zero-to-first sound transition in
a finite nuclear system.Comment: 15 pages, 4 figure
Bulk properties of rotating nuclei and the validity of the liquid drop model at finite angular momenta
Out of self-consistent semi-classical calculations performed within the
so-called Extended Thomas-Fermi approach for 212 nuclei at all even angular
momentum values I ranging between 0 and 80 \hbar and using the Skyrme SkM*
effective force, the I-dependence of associated liquid drop model parameters
has been studied. The latter have been obtained trough separate fits of the
calculated values of the strong interaction as well as direct and exchange
Coulomb energies. The theoretical data basis so obtained, has allowed to make a
rough quantitative assessment of the variation with I of the usual volume and
surface energy parameters up to spin of \sim 30-40 \hbar. As a result of the
combined variation of the surface and Coulomb energies, it has been shown that
this I-dependence results in a significant enhancement of the fission stability
of very heavy nuclei, balancing thus partially the well-known instability due
to centrifugal forces.Comment: 27 pages, LaTeX (elsart) with 13 embeded postscript figure
Influence of an increase in diet structure on milk conjugated linoleic acid content of cows fed extruded linseed
Fish Oil Increases the Duodenal Flow of Long Chain Polyunsaturated Fatty Acids and trans-11 18:1 and Decreases 18:0 in Steers via Changes in the Rumen Bacterial Community
Ruminant fat is rich in SFA, partly due to the biohydrogenation of dietary PUFA to SFA in the rumen. This process can be inhibited by the dietary inclusion of fish oil. The only bacteria isolated from the rumen capable of converting PUFA to SFA are closely related to Clostridium proteoclasticum. The aim of this study was to investigate if a correlation could be found in vivo between dietary fish oil inclusions and the composition of the ruminal bacterial community and specifically of C. proteoclasticum. Six Hereford × Friesian steers, prepared with ruminal and duodenal cannulae, received grass silage plus 1 of 3 concentrates resulting in total dietary fish oil contents of 0, 1, or 3% of dry matter. A dual flow marker technique was employed to estimate the relative flow of fatty acids. Steers fed the 3% fish oil diet had 100% increases in trans 18:1 flow, whereas 18:0 flow declined to 39% of steers fed the control diet. 16S ribosomal RNA-based denaturing gradient gel electrophoresis profiles obtained from ruminal digesta showed major changes in the bacterial community within steers fed the 3% fish oil diet. Quantitative PCR indicated only a weak relation between numbers of C. proteoclasticum and 18:0 flow between treatments and in individual steers (P < 0.05, but the percentage variance accounted for only 22.8) and did not provide unambiguous evidence that numbers of C. proteoclasticum in the rumen dictate the ratios of SFA:PUFA available for absorption by the animal. Understanding which microbes biohydrogenate PUFA in the rumen is key to developing novel strategies to improve the quality of ruminant products