1,321 research outputs found
The Neutron Halo in Heavy Nuclei Calculated with the Gogny Force
The proton and neutron density distributions, one- and two-neutron separation
energies and radii of nuclei for which neutron halos are experimentally
observed, are calculated using the self-consistent Hartree-Fock-Bogoliubov
method with the effective interaction of Gogny. Halo factors are evaluated
assuming hydrogen-like antiproton wave functions. The factors agree well with
experimental data. They are close to those obtained with Skyrme forces and with
the relativistic mean field approach.Comment: 13 pages in Latex and 17 figures in ep
Effect of differences in proton and neutron density distributions on fission barriers
The neutron and proton density distributions obtained in constrained
Hartree-Fock-Bogolyubov calculations with the Gogny force along the fission
paths of 232Th, 236U, 238U and 240Pu are analyzed.
Significant differences in the multipole deformations of neutron and proton
densities are found. The effect on potential energy surfaces and on barrier
heights of an additional constraint imposing similar spatial distributions to
neutrons and protons, as assumed in macroscopic-microscopic models, is studied.Comment: 5 pages in Latex, 4 figures in ep
Open Problems in Particle Condensation
particle condensation is a novel state in nuclear systems. We
briefly review the present status on the study of particle
condensation and address the open problems in this research field:
particle condensation in heavier systems other than the Hoyle state, linear
chain and particle rings, Hoyle-analogue states with extra neutrons,
particle condensation related to astrophysics, etc.Comment: 12 pages. To be published in J. of Phys. G special issue on Open
Problems in Nuclear Structure (OPeNST
Fingermark age determinations: Legal considerations, review of the literature and practical propositions.
The question of the age of fingermarks is often raised in investigations and trials when suspects admit that they have left their fingermarks at a crime scene but allege that the contact occurred at a different time than the crime and for legal reasons. In the first part of this review article, examples from American appellate court cases will be used to demonstrate that there is a lack of consensus among American courts regarding the admissibility and weight of testimony from expert witnesses who provide opinions about the age of fingermarks. Of course, these issues are not only encountered in America but have also been reported elsewhere, for example in Europe. The disparity in the way fingermark dating cases were managed in these examples is probably due to the fact that no methodology has been validated and accepted by the forensic science community so far. The second part of this review article summarizes the studies reported on fingermark dating in the literature and highlights the fact that most proposed methodologies still suffer from limitations preventing their use in practice. Nevertheless, several approaches based on the evolution of aging parameters detected in fingermark residue over time appear to show promise for the fingermark dating field. Based on these approaches, the definition of a formal methodological framework for fingermark dating cases is proposed in order to produce relevant temporal information. This framework identifies which type of information could and should be obtained about fingermark aging and what developments are still required to scientifically address dating issues
The Archaeological Sites of Gadani and Phuari Headlands (Las Bela, Balochistan, Pakistan)
Ras Gadani and Phuari were surveyed in the 2000s by the Italian Archaeological Mission in Las Bela
and Lower Sindh. The discovery of a few sites on the two headlands has shown the importance of the
Las Bela coast for the archaeology of the northern Arabian Sea. Both capes were already known for
their complex geological history, the presence of Bela Ophiolite outcrops and Parh Limestone formations
containing good quality red flint nodules, which were exploited at least since the beginning of the
Holocene. The recent surveys have led to the discovery of a few shell scatters, whose characteristics,
material culture remains and radiocarbon dating have contributed to improving our knowledge of the
peopling of the coastal region during two main periods of prehistory and history
Prehistoric Shell Middens, Seascapes and Landscapes at Lake Siranda (Las bela, Balochistan): Preliminary Results of the 2011 Fieldwork Season
Preliminary results of the surveys conducted in 2011 along the shores of Lake Siranda (Las Bela, Balochistan) that led to the discovery of two shell middens radiocarbon dated to the 7th and 6th millennium uncal B
Approximate particle number projection for finite range density dependent forces
The Lipkin-Nogami method is generalized to deal with finite range density
dependent forces. New expressions are derived and realistic calculations with
the Gogny force are performed for the nuclei Er and Er. The
sharp phase transition predicted by the mean field approximation is washed out
by the Lipkin-Nogami approach; a much better agreement with the experimental
data is reached with the new approach than with the Hartree-Fock_Bogoliubov
one, specially at high spins.Comment: 5 pages, RevTeX 3.0, 3 postscript figures included using uufiles.
Submitted to Phys. Rev. Let
Clinical and hemodynamic follow-up of left ventricular to aortic conduits in patients with aortic stenosis
To assess the long-term results of left ventricular outflow tract reconstruction utilizing an apical left ventricular to aortic valved (porcine) conduit the clinical and hemodynamic data were reviewed from 24 patients who had placement of an apico-aortic conduit. Eighteen of the patients are asymptomatic and taking no cardiac medications. Three patients were reoperated on, one patient 1.5 years after his original operation for subacute bacterial endocarditis and two patients 3 to 4 years after their original operation for severe conduit valve insufficiency. None of the patients is taking anticoagulants and no thromboembolic events have occurred. Postoperative catheterization has been performed 1 to 1.5 years (mean 1.2) after repair in 15 of 21 patients. The rest left ventricular outflow tract gradient has decreased from 102.5 ± 20 mm Hg preoperatively to 14.8 ± 9.9 mm Hg postoperatively (probability [p] < 0.001). Some degree of conduit obstruction was demonstrated by catheter passage in 11 of the 15 patients. In these 11 patients, the obstruction occurred at three distant sites: at the egress of the left ventricle in 9, at the porcine valve in 5 and at the aortic to conduit junction in 1. Isometric exercise in five and supine bicycle exercise in six patients increased the left ventricular outflow tract gradient by 2.5 ± 1.1 and 20.8 ± 11.8 mm Hg, respectively, despite an increase in cardiac index of 1 ± 0.3 and 3.7 ± 0.4 liters/min per m2, respectively. The data suggest that a left ventricular to aortic conduit is an effective form of therapy for severe left ventricular outflow tract obstruction
The Middle Holocene mangrove shellfish gatherers of Las Bela coast (Balochistan, Pakistan): new AMS dates from Lake Siranda shell middens
The discovery and AMS dating of many shell middens along the shores of the dry basin of Lake Siranda (Las Bela, Balochistan, Pakistan) have shown that it was a lagoon in the northern coast of the Arabian Sea in Neolithic times, densely settled by communities of mangrove shellfish gatherers
Point symmetries in the Hartree-Fock approach: Symmetry-breaking schemes
We analyze breaking of symmetries that belong to the double point group
D2h(TD) (three mutually perpendicular symmetry axes of the second order,
inversion, and time reversal). Subgroup structure of the D2h(TD) group
indicates that there can be as much as 28 physically different, broken-symmetry
mean-field schemes --- starting with solutions obeying all the symmetries of
the D2h(TD) group, through 26 generic schemes in which only a non-trivial
subgroup of D2h(TD) is conserved, down to solutions that break all of the
D2h(TD) symmetries. Choices of single-particle bases and the corresponding
structures of single-particle hermitian operators are discussed for several
subgroups of D2h(TD).Comment: 10 RevTeX pages, companion paper in nucl-th/991207
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