oalib

OALib Journal期刊

ISSN: 2333-9721

费用:99美元

投稿

匹配条件: “Giai” ,找到相关结果约95条。
列表显示的所有文章,均可免费获取
第1页/共95条
每页显示
Cadenas productivas y disponibilidad de alimentos en Argentina
Giai,Malena; Veronesi,Guillermina;
Diaeta , 2010,
Abstract: in april 2009, was formed in the argentina association of dieticians and nutritionists dietitians the study group on food sovereignty, established by a group of graduates in nutrition with interest in the subject. as a first objective, the group was to examine three issues: "the right to food", "production and availability of food in argentina" and "basic food basket." this article is a summary of progress on the second topic mentioned.
Cadenas productivas y disponibilidad de alimentos en Argentina Productive chains and food availability in Argentina
Malena Giai,Guillermina Veronesi
Diaeta , 2010,
Abstract: En abril de 2009 se conformó en la Asociación Argentina de Dietistas y Nutricionistas Dietistas el Grupo de Estudio sobre Soberanía Alimentaria, constituido por un grupo de Licenciados en Nutrición con interés en el tema. Como primer objetivo, el Grupo se propuso estudiar tres temas: "el Derecho a la Alimentación", "la Producción y Disponibilidad de alimentos en Argentina" y "la Canasta Básica de Alimentos". En el presente artículo se expone un resumen de los avances en el segundo tema mencionado. In April 2009, was formed in the Argentina Association of Dieticians and Nutritionists Dietitians the Study Group on Food Sovereignty, established by a group of graduates in nutrition with interest in the subject. As a first objective, the Group was to examine three issues: "The Right to Food", "Production and Availability of food in Argentina" and "Basic Food Basket." This article is a summary of progress on the second topic mentioned.
Theoretical understanding of the nuclear incompressibility: where do we stand ?
G. Colo`,N. Van Giai
Physics , 2003, DOI: 10.1016/j.nuclphysa.2003.11.014
Abstract: The status of the theoretical research on the compressional modes of finite nuclei and the incompressibility $K_\infty$ of nuclear matter, is reviewed. It is argued that the recent experimental data on the Isoscalar Giant Monopole Resonance (ISGMR) allow extracting the value of $K_\infty$ with an uncertainity of about $\pm$ 12 MeV. Non-relativistic (Skyrme, Gogny) and relativistic mean field models predict for $K_\infty$ values which are significantly different from one another, namely $\approx$ 220-235 and $\approx$ 250-270 MeV respectively. It is shown that the solution of this puzzle requires a better determination of the symmetry energy at, and around, saturation. The role played by the experimental data of the Isoscalar Giant Dipole Resonance (ISGDR) is also discussed.
Deformed quasiparticle-random-phase approximation for neutron-rich nuclei using the Skyrme energy density functional
Kenichi Yoshida,Nguyen Van Giai
Physics , 2008, DOI: 10.1103/PhysRevC.78.064316
Abstract: We develop a new framework of the deformed quasiparticle-random-phase approximation (QRPA) where the Skyrme density functional and the density-dependent pairing functional are consistently treated. Numerical applications are carried out for the isovector dipole and the isoscalar quadrupole modes in the spherical $^{20}$O and in the deformed $^{26}$Ne nuclei, and the effect of the momentum dependent terms of the Skyrme effective interaction for the energy-weighted sum rule is discussed. As a further application, we present for the first time the moments of inertia of $^{34}$Mg and $^{36}$Mg using the Thouless-Valatin procedure based on the self-consistent deformed QRPA, and show the applicability of our new calculation scheme not only for the vibrational modes but also for the rotational modes in neutron-rich nuclei.
Low-lying dipole resonance in neutron-rich Ne isotopes
Kenichi Yoshida,Nguyen Van Giai
Physics , 2008, DOI: 10.1103/PhysRevC.78.014305
Abstract: Microscopic structure of the low-lying isovector dipole excitation mode in neutron-rich $^{26,28,30}$Ne is investigated by performing deformed quasiparticle-random-phase-approximation (QRPA) calculations. The particle-hole residual interaction is derived from a Skyrme force through a Landau-Migdal approximation. We have obtained the low-lying resonance in $^{26}$Ne at around 8.5 MeV. It is found that the isovector dipole strength at $E_{x}<10$ MeV exhausts about 6.0% of the classical Thomas-Reiche-Kuhn dipole sum rule. This excitation mode is composed of several QRPA eigenmodes, one is generated by a $\nu(2s^{-1}_{1/2} 2p_{3/2})$ transition dominantly, and the other mostly by a $\nu(2s^{-1}_{1/2} 2p_{1/2})$ transition. The neutron excitations take place outside of the nuclear surface reflecting the spatially extended structure of the $2s_{1/2}$ wave function. In $^{30}$Ne, the deformation splitting of the giant resonance is large, and the low-lying resonance is overlapping with the giant resonance.
Pairing effects on the collectivity of quadrupole states around 32Mg
M. Yamagami,Nguyen Van Giai
Physics , 2003, DOI: 10.1103/PhysRevC.69.034301
Abstract: The first 2+ states in N=20 isotones including neutron-rich nuclei 32Mg and 30Ne are studied by the Hartree-Fock-Bogoliubov plus quasiparticle random phase approximation method based on the Green's function approach. The residual interaction between the quasiparticles is consistently derived from the hamiltonian density of Skyrme interactions with explicit velocity dependence. The B(E2) transition probabilities and the excitation energies of the first 2+ states are well described within a single framework. We conclude that pairing effects account largely for the anomalously large B(E2) value and the very low excitation energy in 32Mg.
A self-consistent QRPA study of quadrupole collectivity around 32Mg
Masayuki Yamagami,Nguyen Van Giai
Physics , 2003,
Abstract: On the basis of the Hartree-Fock-Bogoliubov (HFB) plus quasiparticle random phase approximation method (QRPA) based on the Green's function approach with Skyrme force, we discuss the anomalous E2 properties of the first 2+ states in neutron-rich nuclei 32Mg and 30Ne. The B(E2) values and the excitation energies of the first 2+ states are well described within HFB plus QRPA calculations with spherical symmetry. We conclude that pairing effects account largely for the anomalously large B(E2) values and the low excitation energies in 32Mg and 30Ne.
Low-Lying 2+ states in neutron-rich oxygen isotopes in quasiparticle random phase approximation
E. Khan,Nguyen Van Giai
Physics , 1999, DOI: 10.1016/S0370-2693(99)01437-9
Abstract: The properties of the low-lying, collective 2+ states in neutron-rich oxygen isotopes are investigated in the framework of self-consistent microscopic models with effective Skyrme interactions. In RPA the excitation energies E2+ can be well described but the transition probabilities are much too small as compared to experiment. Pairing correlations are then accounted for by performing quasiparticle RPA calculations. This improves considerably the predictions of B(E2) values and it enables one to calculate more reliably the ratios Mn/Mp of neutron-to-proton transition amplitudes. A satisfactory agreement with the existing experimental values of Mn/Mp is obtained.
Structure of positive energy states in a deformed mean-field potential
K. Hagino,Nguyen Van Giai
Physics , 2003, DOI: 10.1016/j.nuclphysa.2004.02.002
Abstract: We investigate the properties of single-particle resonances in a non-spherical potential by solving the coupled-channels equations for the radial wave functions. We first generalize the box discretization method for positive energy states to a deformed system. As in the spherical case, we find that the discretized energy is stabilized against the box size when a resonance condition is met. Using the wave functions thus obtained, we then discuss the energy and the radial dependences of scattering wave functions in the vicinity of an isolated resonance. In the eigenchannel basis, where the $S$-matrix is diagonal, we propose a generalized expression for the factorization formula for the multi-channel wave function. We find that the factorized wave function agrees well with the exact solution inside the centrifugal barrier when the energy distance from the resonance is less than the resonance width.
Testing instantaneous causality in presence of non constant unconditional variance
Quentin Giai Gianetto,Hamdi Raissi
Statistics , 2012,
Abstract: The problem of testing instantaneous causality between variables with time-varying unconditional variance is investigated. It is shown that the classical tests based on the assumption of stationary processes must be avoided in our non standard framework. More precisely we underline that the standard test does not control the type I errors, while the tests with White (1980) and Heteroscedastic Autocorrelation Consistent (HAC) corrections can suffer from a severe loss of power when the variance is not constant. Consequently a modified test based on a bootstrap procedure is proposed. The relevance of the modified test is underlined through a simulation study. The tests considered in this paper are also compared by investigating the instantaneous causality relations between US macroeconomic variables.
第1页/共95条
每页显示


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.