Correlations in self-bound systems of identical fermions

A method for the calculation of translationally invariant wave functions for systems of identical fermions with arbitrary potential of pair interaction is developed. It is based on the well-known result that the essential dynamic part of the Hamiltonian for the system of identical particles is the Reduced Hamiltonian operator describing relative movement of two particles inside the system. The eigenfunctions of this operator take into account all correlations caused by interaction. These eigenfunctions are basic for the construction of the components (i.e. the functions with a lower degree of antisymmetry) of the system wave functions. The main problem of this approach appears to be antisymmetrization of the components. The developed universal algorithm for antisymmetrization gives a possibility to perform this operation in a simple way and keep numerical approximations under control.Comment: 20 pages REVTeX, submitted to Lithuanian J. Phy

Isoscalar Hamiltonians for light atomic nuclei

The charge-dependent realistic nuclear Hamiltonian for a nucleus, composed of neutrons and protons, can be successfully approximated by a charge-independent one. The parameters of such a Hamiltonian, i.e., the nucleon mass and the NN potential, depend upon the mass number A, charge Z and isospin quantum number T of state of the studied nucleus.Comment: REVTeX, 22 pages, 3 eps figures, to appear in PR

Percutaneous coronary angioplasty versus coronary artery bypass grafting in treatment of unprotected left main stenosis (NOBLE) : a prospective, randomised, open-label, non-inferiority trial

Background Coronary artery bypass grafting (CABG) is the standard treatment for revascularisation in patients with left main coronary artery disease, but use of percutaneous coronary intervention (PCI) for this indication is increasing. We aimed to compare PCI and CABG for treatment of left main coronary artery disease. Methods In this prospective, randomised, open-label, non-inferiority trial, patients with left main coronary artery disease were enrolled in 36 centres in northern Europe and randomised 1: 1 to treatment with PCI or CABG. Eligible patients had stable angina pectoris, unstable angina pectoris, or non-ST-elevation myocardial infarction. Exclusion criteria were ST-elevation myocardial infarction within 24 h, being considered too high risk for CABG or PCI, or expected survival of less than 1 year. The primary endpoint was major adverse cardiac or cerebrovascular events (MACCE), a composite of all-cause mortality, non-procedural myocardial infarction, any repeat coronary revascularisation, and stroke. Non-inferiority of PCI to CABG required the lower end of the 95% CI not to exceed a hazard ratio (HR) of 1 . 35 after up to 5 years of follow-up. The intention-to-treat principle was used in the analysis if not specified otherwise. This trial is registered with ClinicalTrials.gov identifier, number NCT01496651. Findings Between Dec 9, 2008, and Jan 21, 2015, 1201 patients were randomly assigned, 598 to PCI and 603 to CABG, and 592 in each group entered analysis by intention to treat. Kaplan-Meier 5 year estimates of MACCE were 29% for PCI (121 events) and 19% for CABG (81 events), HR 1 . 48 (95% CI 1 . 11-1 . 96), exceeding the limit for non-inferiority, and CABG was significantly better than PCI (p=0 . 0066). As-treated estimates were 28% versus 19% (1 . 55, 1 . 18-2 . 04, p= 0 . 0015). Comparing PCI with CABG, 5 year estimates were 12% versus 9% (1 . 07, 0 . 67-1 . 72, p= 0 . 77) for all-cause mortality, 7% versus 2% (2 . 88, 1 . 40-5 . 90, p= 0 . 0040) for non-procedural myocardial infarction, 16% versus 10% (1 . 50, 1 . 04-2 . 17, p= 0 . 032) for any revascularisation, and 5% versus 2% (2 . 25, 0 . 93-5 . 48, p= 0 . 073) for stroke. Interpretation The findings of this study suggest that CABG might be better than PCI for treatment of left main stem coronary artery disease.Peer reviewe

Converging upper and lower bounds for ground-state energies of atomic nuclei

By expanding the wave function in terms of the translationally invariant basis of harmonic oscillator functions, we calculate the converging upper (variational) bound for the energy. It is shown that one can construct lower bounds using the reduced density matrix that corresponds to the upper bound. These lower bounds converge to an exact value with the expansion of the basis. We perform the calculations of both bounds with realistic nucleon-nucleon potential for ground states of the triton and the alpha-particle

Oscillator representation of effective NN potentials

Nuo 2003 m. ISSN 1648-8504Fizikos katedraTaikomosios informatikos katedraVytauto Didžiojo universiteta