18,810 research outputs found
Proton emission induced by polarized photons
The proton emission induced by polarized photons is studied in the energy
range above the giant resonance region and below the pion emission threshold.
Results for the 12C, 16O and 40Ca nuclei are presented. The sensitivity of
various observables to final state interaction, meson exchange currents and
short range correlations is analyzed. We found relevant effects due to the
virtual excitation of the resonance.Comment: 12 pages, 11 figures, 1 tabl
Model calculations of doubly closed shell nuclei in CBF theory III. j-j coupling and isospin dependence
Correlated Basis Function theory and Fermi Hypernetted Chain technique are
extended to study medium-heavy, doubly closed shell nuclei in j-j coupling
scheme, with different single particle wave functions for protons and neutrons
and isospin dependent two-body correlations. Central semirealistic interactions
are used. Ground state energies, one-body densities, distribution functions and
momentum distributions are calculated for 12C, 16O, 40Ca, 48Ca and 208Pb
nuclei. The values of the ground state energies provided by isospin dependent
correlations are lower than those obtained with isospin independent
correlations. In finite nuclear systems, the two--body Euler equations provide
correlation functions variationally more effective than those obtained with the
same technique in infinite nuclear matter.Comment: 29 Latex pages plus 6 Postscript figure
Liver resection for metastatic colorectal cancer
From 1975 to 1985, 60 patients with isolated hepatic metastases from colorectal cancer were treated by 17 right trisegmentectomies, five left trisegmentectomies, 20 right lobectomies, seven left lobectomies, eight left lateral segmentectomies, and three nonanatomic wedge resections. The 1-month operative mortality rate was 0%. One- to 5-year actuarial survival rates of the 60 patients were 95%, 72%, 53%, 45%, and 45%, respectively. The survival rate after liver resection was the same when solitary lesions were compared with multiple lesions. However, none of the seven patients with four or more lesions survived 3 years. The interval after colorectal resection did not influence the survival rate after liver resection, and survival rates did not differ statistically when synchronous metastases were compared with metachronous tumors. A significant survival advantage of patients with Dukes' B primary lesions was noted when compared with Dukes' C and D lesions. The pattern of tumor recurrence after liver resection appeared to be systemic rather than hepatic. The patients who received systemic chemotherapy before clinical evidence of tumor recurrence after liver resection survived longer than those who did not
Liver transplantation across ABO blood groups
Six hundred seventy-one first, second, and third orthotopic liver allografts in 520 patients were reviewed to determine the effect of donor-recipient mismatches or incompatibility for the ABO blood group on graft survival. A significant advantage for ABO donor-recipient identity was found, especially in adults and for first grafts. However, a surprisingly large number of ABO incompatible grafts were successful. We recommend that nonidentical or incompatible grafts be limited to patients such as small children for whom the supply of available donors is severely limited or for patients in urgent need of transplantation or retransplantation
Correlations and charge distributions of medium heavy nuclei
The effects of long- and short-range correlations on the charge distributions
of some medium and heavy nuclei are investigated. The long-range correlations
are treated within the Random Phase Approximation framework and the short-range
correlations with a model inspired to the Correlation Basis Function theory.
The two type of correlations produce effects of the same order of magnitude. A
comparison with the empirical charge distribution difference between 206Pb and
205Tl shows the need of including both correlations to obtain a good
description of the data.Comment: 20 pages, Latex, accepted for publication in Jour. Phys.
Magnetic excitations in nuclei with neutron excess
The excitation of the , and modes in O, O,
O, O, Ca, Ca, Ca and Ca nuclei is
studied with self-consistent random phase approximation calculations.
Finite-range interactions of Gogny type, containing also tensor-isospin terms,
are used. We analyze the evolution of the magnetic resonances with the
increasing number of neutrons, the relevance of collective effects, the need of
a correct treatment of the continuum and the role of the tensor force.Comment: 18 pages, 12 figures, 2 tables, accepted for publication in Physical
Review
Low-lying magnetic excitations of doubly-closed-shell nuclei and nucleon-nucleon effective interactions
We have studied the low lying magnetic spectra of 12C, 16O, 40Ca, 48Ca and
208Pb nuclei within the Random Phase Approximation (RPA) theory, finding that
the description of low-lying magnetic states of doubly-closed-shell nuclei
imposes severe constraints on the spin and tensor terms of the nucleon-nucleon
effective interaction. We have first made an investigation by using four
phenomenological effective interactions and we have obtained good agreement
with the experimental magnetic spectra, and, to a lesser extent, with the
electron scattering responses. Then we have made self-consistent RPA
calculations to test the validity of the finite-range D1 Gogny interaction. For
all the nuclei under study we have found that this interaction inverts the
energies of all the magnetic states forming isospin doublets.Comment: 19 pages, 13 figures, 7 tables, accepted for publication in Phys.
Rev.
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