173 research outputs found
Relativistic Hartree-Bogoliubov theory with finite range pairing forces in coordinate space: Neutron halo in light nuclei
The Relativistic Hartree Bogoliubov (RHB) model is applied in the
self-consistent mean-field approximation to the description of the neutron halo
in the mass region above the s-d shell. Pairing correlations and the coupling
to particle continuum states are described by finite range two-body forces.
Finite element methods are used in the coordinate space discretization of the
coupled system of Dirac-Hartree-Bogoliubov integro-differential eigenvalue
equations, and Klein-Gordon equations for the meson fields. Calculations are
performed for the isotopic chains of Ne and C nuclei. We find evidence for the
occurrence of neutron halo in heavier Ne isotopes. The properties of the 1f-2p
orbitals near the Fermi level and the neutron pairing interaction play a
crucial role in the formation of the halo. Our calculations display no evidence
for the neutron halo phenomenon in C isotopes.Comment: 7 pages, Latex, 5 P.S. Figures, To appear in Phys. Rev. Let
Mass ingestion of gastroliths and other foreign bodies in three juvenile hooded seals (Cystophora cristata) stranded in north-western Iberian Peninsula
We present here three clinical cases involving mass ingestion of foreign bodies in Hooded seals (Cystophora cristata) stranded in north-western Iberian Peninsula. Although the presence of gastroliths is considered to be normal in pinnipeds, the cases presented here highlight how an excessive presence of them as well as other foreign bodies could result in rapid onset of a potentially lethal gastrointestinal stasis syndrome, which has to be quickly resolved, medically or surgically. Ultrasound examinations and posterior X-ray confirmation have demonstrated their utility to a rapid detection of gastric bodies, and have to be taken into account in Hooded seal routine clinical protocols. Finally, we conclude that it is particularly important to avoid the use of loose stones or sand over resting areas and to take extreme precautions with small items near the rehabilitation pools when dealing with this seal species.JM Alonso-FarrĂ© and M. Llarena-Reino are currently funded by Fundação para a CiĂȘncia e a Tecnologia, (Portugal), under post-doctoral fellowship SFRH/BPD/47251/2008, and pre-doctoral grant SFRH/BD/45398/2008, respectively.Peer reviewe
Relativistic Hartree-Bogoliubov description of the deformed ground-state proton emitters
Ground-state properties of deformed proton-rich odd-Z nuclei in the region
are described in the framework of Relativistic Hartree
Bogoliubov (RHB) theory. One-proton separation energies and ground-state
quadrupole deformations that result from fully self-consistent microscopic
calculations are compared with available experimental data. The model predicts
the location of the proton drip-line, the properties of proton emitters beyond
the drip-line, and provides information about the deformed single-particle
orbitals occupied by the odd valence proton.Comment: 9 pages, RevTeX, 3 PS figures, submitted Phys. Rev. Letter
Relativistic Hartree-Bogoliubov description of ground-state properties of Ni and Sn isotopes
The Relativistic Hartree Bogoliubov (RHB) theory is applied in the
description of ground-state properties of Ni and Sn isotopes. The NL3 parameter
set is used for the effective mean-field Lagrangian, and pairing correlations
are described by the pairing part of the finite range Gogny interaction D1S.
Fully self-consistent RHB solutions are calculated for the Ni () and Sn () isotopes. Binding energies, neutron separation
energies, and proton and neutron radii are compared with experimental
data. The model predicts a reduction of the spin-orbit potential with the
increase of the number of neutrons. The resulting energy splittings between
spin-orbit partners are discussed, as well as pairing properties calculated
with the finite range effective interaction in the channel.Comment: 11 pages, RevTex, 12 p.s figures, submitted to Phys. Rev.
TVB-EduPack: An interactive learning and scripting platform for The Virtual Brain
The Virtual Brain (TVB; thevirtualbrain.org) is a neuroinformatics platform for full brain network simulation based on individual anatomical connectivity data. The framework addresses clinical and neuroscientific questions by simulating multi-scale neural dynamics that range from local population activity to large-scale brain function and related macroscopic signals like electroencephalography and functional magnetic resonance imaging. TVB is equipped with a graphical and a command-line interface to create models that capture the characteristic biological variability to predict the brain activity of individual subjects. To enable researchers from various backgrounds a quick start into TVB and brain network modeling in general, we developed an educational module: TVB-EduPack. EduPack offers two educational functionalities that seamlessly integrate into TVB's graphical user interface (GUI): (i) interactive tutorials introduce GUI elements, guide through the basic mechanics of software usage and develop complex use-case scenarios; animations, videos and textual descriptions transport essential principles of computational neuroscience and brain modeling; (ii) an automatic script generator records model parameters and produces input files for TVB's Python programming interface; thereby, simulation configurations can be exported as scripts that allow flexible customization of the modeling process and self-defined batch- and post-processing applications while benefitting from the full power of the Python language and its toolboxes. This article covers the implementation of TVB-EduPack and its integration into TVB architecture. Like TVB, EduPack is an open source community project that lives from the participation and contribution of its users. TVB-EduPack can be obtained as part of TVB from thevirtualbrain.org
MiR-219a-5p Enriched Extracellular Vesicles Induce OPC Differentiation and EAE Improvement More Efficiently Than Liposomes and Polymeric Nanoparticles
Remyelination is a key aspect in multiple sclerosis pathology and a special effort is being made to promote it. However, there is still no available treatment to regenerate myelin and several strategies are being scrutinized. Myelination is naturally performed by oligodendrocytes and microRNAs have been postulated as a promising tool to induce oligodendrocyte precursor cell differentiation and therefore remyelination. Herein, DSPC liposomes and PLGA nanoparticles were studied for miR-219a-5p encapsulation, release and remyelination promotion. In parallel, they were compared with biologically engineered extracellular vesicles overexpressing miR-219a-5p. Interestingly, extracellular vesicles showed the highest oligodendrocyte precursor cell differentiation levels and were more effective than liposomes and polymeric nanoparticles crossing the bloodâbrain barrier. Finally, extracellular vesicles were able to improve EAE animal model clinical evolution. Our results indicate that the use of extracellular vesicles as miR-219a-5p delivery system can be a feasible and promising strategy to induce remyelination in multiple sclerosis patients.This work was supported by Carlos III Institute, (PI17/00189 and DTS15/00069), by Fondo Europeo
de Desarrollo RegionalâFEDER, by the Gipuzkoa Regional Council (DFG 15/006), by grant from the Basque
Government (RIS3/DTS/2018222025), by the Department of Industry of the Basque Country (ELKARTEK 16/014),
and the Spanish State Research Agency (SAF2017-87670-R) and Maria de Maeztu Units of Excellence Program
Grant MDM-2017-0720). I.O.-Q., A.A. and L.I. were supported by the Department of Education of the Basque
Government. IOQ and LAN were supported by EMBO short Term Fellowship Programme. LAN was supported
by a Canadian graduate scholarship from the Canadian Institutes of Health Research (CGS-D CIHR).PRC was
supported by Ikerbasque, the Basque Foundation for Science
Proton drip-line nuclei in Relativistic Hartree-Bogoliubov theory
Ground-state properties of spherical even-even nuclei and
are described in the framework of Relativistic Hartree Bogoliubov
(RHB) theory. The model uses the NL3 effective interaction in the mean-field
Lagrangian, and describes pairing correlations by the pairing part of the
finite range Gogny interaction D1S. Binding energies, two-proton separation
energies, and proton radii that result from fully self-consistent RHB
solutions are compared with experimental data. The model predicts the location
of the proton drip-line. The isospin dependence of the effective spin-orbit
potential is discussed, as well as pairing properties that result from the
finite range interaction in the channel.Comment: 12 pages, RevTex, 10 p.s figures, submitted to Phys. Rev.
Shell Effects in Nuclei with Vector Self-Coupling of Omega Meson in Relativistic Hartree-Bogoliubov Theory
Shell effects in nuclei about the stability line are investigated within the
framework of the Relativistic Hartree-Bogoliubov (RHB) theory with
self-consistent finite-range pairing. Using 2-neutron separation energies of Ni
and Sn isotopes, the role of - and -meson couplings on the
shell effects in nuclei is examined. It is observed that the existing
successful nuclear forces (Lagrangian parameter sets) based upon the nonlinear
scalar coupling of -meson exhibit shell effects which are stronger than
suggested by the experimental data. We have introduced nonlinear vector
self-coupling of -meson in the RHB theory. It is shown that the
inclusion of the vector self-coupling of -meson in addition to the
nonlinear scalar coupling of -meson provides a good agreement with the
experimental data on shell effects in nuclei about the stability line. A
comparison of the shell effects in the RHB theory is made with the Hartree-Fock
Bogoliubov approach using the Skyrme force SkP. It is shown that the
oft-discussed shell quenching with SkP is not consistent with the available
experimental data.Comment: 34 pages latex, 18 ps figures, replaced with minor corrections in
some figures, accepted for publication in Phys. Rev.
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