609 research outputs found
Radii in the shell and the "halo" orbit: A game changer
Proton radii of nuclei in the shell depart appreciably from the
asymptotic law, . The departure exhibits systematic
trends fairly well described by a single phenomenological term in the
Duflo-Zuker formulation, which also happens to explain the sudden increase in
slope in the isotope shifts of several chains at neutron number . It was
recently shown that this term is associated with the abnormally large size of
the and orbits in the and shells respectively. Further
to explore the problem, we propose to calculate microscopically radii in the
former. Since the (square) radius is basically a one body operator, its
evolution is dictated by single particle occupancies determined by shell model
calculations. Assuming that the departure from the asymptotic form is entirely
due to the orbit, the expectation value is determined by demanding that its evolution be
such as to describe well nuclear radii. It does, for an orbit that remains very
large (about 1.6 fm bigger than its counterparts) up to then
drops abruptly but remains some 0.6 fm larger than the orbits. An
unexpected behavior bound to challenge our understanding of shell formation.Comment: 4 pages 6(7) figure
Neutron Skins and Halo Orbits in the sd and pf Shells
open3siThe strong dependence of Coulomb energies on nuclear radii makes it possible to extract the latter from
calculations of the former. The resulting estimates of neutron skins indicate that two mechanisms are
involved. The first one --isovector monopole polarizability—amounts to noting that when a particle is
added to a system it drives the radii of neutrons and protons in different directions, tending to equalize the
radii of both fluids independently of the neutron excess. This mechanism is well understood and the Duflo-
Zuker (small) neutron skin values derived 14 years ago are consistent with recent measures and estimates.
The alternative mechanism involves halo orbits whose huge sizes tend to make the neutron skins larger and
have a subtle influence on the radial behavior of sd and f shell nuclei. In particular, they account for the
sudden rise in the isotope shifts of nuclei beyond N=28 and the near constancy of radii in the A=40–56
region. This mechanism, detected here for the first time, is not well understood and may well go beyond the
Efimov physics usually associated with halo orbits.openBonnard, JEREMY CHRISTIAN FREDERIC; Lenzi, SILVIA MONICA; Zuker, A. P.Bonnard, JEREMY CHRISTIAN FREDERIC; Lenzi, SILVIA MONICA; Zuker, A. P
General unifying features of controlled quantum phenomena
Many proposals have been put forth for controlling quantum phenomena,
including open-loop, adaptive feedback, and real-time feedback control. Each of
these approaches has been viewed as operationally, and even physically,
distinct from the others. This work shows that all such scenarios inherently
share the same fundamental control features residing in the topology of the
landscape relating the target physical observable to the applied controls. This
unified foundation may provide a basis for development of hybrid control
schemes that would combine the advantages of the existing approaches to achieve
the best overall performance.Comment: The published version (includes the supplementary material
Association between serum cytokine profiles and schistosomiasis-related hepatic fibrosis: Infection by Schistosoma japonicum versus S-mansoni
Edificio de la O.M.S., en Ginebra (Suiza)
This project consists mainly of an administrative block, of 8 storeys, and two basements, which houses the general services, and the administrative and social offices of the World Health Organisation, The social services occupy the top part of the building, so that the marvellous panorama of the Lake Leman, the Jura Mountains and Alps can be admired from its windows. There is also a building containing a lecture hall with a capacity for 400 people, fitted with simultaneous translation services, and which can be occasionally transformed into a cinema.Consta en esencia: 1) De un bloque administrativo, con ocho plantas de altura y dos niveles inferiores, que alojan los servicios: generales; administrativos, y sociales de la Organización Mundial de la Salud (O. M, S.); estos últimos organizados en la parte más alta, con el fin de permitir la observación del maravilloso panorama que se divisa sobre el lago Leman, el Jura y los Alpes. 2) De un edificio, destinado a sala de conferencias, con capacidad para unas 400 personas, dotado de equipos para traducción simultánea, y que en determinadas ocasiones puede transformarse en cine
Global analysis of electromagnetic moments in odd near doubly magic nuclei
We use the nuclear DFT approach to determine nuclear electric quadrupole and
magnetic dipole moments in all one-particle and one-hole neighbors of eight
doubly magic nuclei. We align angular momenta along the intrinsic
axial-symmetry axis with broken time-reversal symmetry, which allows us to
explore fully the self-consistent charge, spin, and current polarizations.
Spectroscopic moments are determined for symmetry-restored wave functions and
compared with available experimental data. We find that the obtained
polarizations do not call for using quadrupole- or dipole-moment operators with
effective charges or effective g-factors.Comment: 15 LaTeX pages, 9 figure
The Serret-Andoyer Riemannian metric and Euler-Poinsot rigid body motion
The Euler-Poinsot rigid body motion is a standard mechanical system and is the model for left-invariant Riemannian metrics on SO(3). In this article, using the Serret-Andoyer variables we parameterize the solutions and compute the Jacobi fields in relation with the conjugate locus evaluation. Moreover the metric can be restricted to a 2D surface and the conjugate points of this metric are evaluated using recent work [4] on surfaces of revolution
The concordance of MRI and arthroscopy in traumatic meniscal lesions in children
SummaryIntroductionTraumatic meniscal lesions in children must be diagnosed quickly and efficiently as a priority in order to conserve the meniscus and safeguard the future of the knee. They are often isolated and difficult to identify clinically. In the diagnostic work up stage, an excessive resort to diagnostic arthroscopy has given way to increasing use of MRI by radiologists without pediatric specialization. The present study examined the agreement between MRI aspect and arthroscopic exploration in traumatic meniscal lesions in children.Patients and methodsSixty-nine knees in children aged 9 to 16 years having undergone MRI followed by arthroscopy for knee trauma between 1995 and 2008 were included in a retrospective design. Discoid meniscus was excluded. Files were reviewed by a single clinician and MRI scans by a radiologist specialized in pediatric pathology. Cases of epiphyseal fusion were excluded. All files were analyzable. Agreement with arthroscopic findings as reference was assessed for presence, location and type of meniscal lesion.ResultsOverall agreement with arthroscopy was respectively 78% and 82% on first and second MRI readings: 77% and 80% for the medial, and 78% and 84% for the lateral meniscus. On the first reading, there were 13 false positives for the medial and 5 for the lateral meniscus, versus 9 and 0 respectively on second reading. Overall sensitivity was 70% on first reading and 64% on second, and overall specificity 81% and 90%, respectively.DiscussionThe present results, in line with the literature, may appear encouraging, but hide considerable disparity between analysis of the medial and of the lateral meniscus: MRI overestimated medial and underestimated lateral meniscus lesions.ConclusionMRI serves only as a support and does not provide sure diagnosis of meniscus lesion. Interpretation should take account of the clinical examination and the pediatric orthopedic specialist's experience.Level of evidenceLevel IV, retrospective study
The Eukaryotic Promoter Database (EPD): recent developments
The Eukaryotic Promoter Database (EPD) is an annotated non-redundant collection of eukaryotic POL II promoters, for which the transcription start site has been determined experimentally. Access to promoter sequences is provided by pointers to positions in nucleotide sequence entries. The annotation part of an entry includes description of the initiation site mapping data, cross-references to other databases, and bibliographic references. EPD is structured in a way that facilitates dynamic extraction of biologically meaningful promoter subsets for comparative sequence analysis. Recent efforts have focused on exhaustive cross-referencing to the EMBL nucleotide sequence database, and on the improvement of the WWW-based user interfaces and data retrieval mechanisms. EPD can be accessed at http://www.epd.isb-sib.c
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