703 research outputs found
Properties of nuclei in the nobelium region studied within the covariant, Skyrme, and Gogny energy density functionals
We calculate properties of the ground and excited states of nuclei in the
nobelium region for proton and neutron numbers of 92 <= Z <= 104 and 144 <= N
<= 156, respectively. We use three different energy-density-functional (EDF)
approaches, based on covariant, Skyrme, and Gogny functionals, each within two
different parameter sets. A comparative analysis of the results obtained for
odd-even mass staggerings, quasiparticle spectra, and moments of inertia allows
us to identify single-particle and shell effects that are characteristic to
these different models and to illustrate possible systematic uncertainties
related to using the EDF modellingComment: 43 LaTeX pages, 14 figures, accepted in Nuclear Physics A, Special
Issue on Superheavy Element
Intermittency at critical transitions and aging dynamics at edge of chaos
We recall that, at both the intermittency transitions and at the Feigenbaum
attractor in unimodal maps of non-linearity of order , the dynamics
rigorously obeys the Tsallis statistics. We account for the -indices and the
generalized Lyapunov coefficients that characterize the
universality classes of the pitchfork and tangent bifurcations. We identify the
Mori singularities in the Lyapunov spectrum at the edge of chaos with the
appearance of a special value for the entropic index . The physical area of
the Tsallis statistics is further probed by considering the dynamics near
criticality and glass formation in thermal systems. In both cases a close
connection is made with states in unimodal maps with vanishing Lyapunov
coefficients.Comment: Proceedings of: STATPHYS 2004 - 22nd IUPAP International Conference
on Statistical Physics, National Science Seminar Complex, Indian Institute of
Science, Bangalore, 4-9 July 2004. Pramana, in pres
Thermal shape fluctuation effects in the description of hot nuclei
The behavior of several nuclear properties with temperature is analyzed
within the framework of the Finite Temperature Hartree-Fock-Bogoliubov (FTHFB)
theory with the Gogny force and large configuration spaces. Thermal shape
fluctuations in the quadrupole degree of freedom, around the mean field
solution, are taken into account with the Landau prescription. As
representative examples the nuclei Er, Dy and Hg are
studied. Numerical results for the superfluid to normal and deformed to
spherical shape transitions are presented. We found a substantial effect of the
fluctuations on the average value of several observables. In particular, we get
a decrease in the critical temperature () for the shape transition as
compared with the plain FTHFB prediction as well as a washing out of the shape
transition signatures. The new values of are closer to the ones found in
Strutinsky calculations and with the Pairing Plus Quadrupole model Hamiltonian.Comment: 17 pages, 8 Figure
Relativistic Hartree plus Bogoliubov description of the deformed N=28 region
Ground-state properties of neutron-rich N≈28 nuclei are described in the framework of relativistic Hartree plus Bogoliubov (RH+B) theory. The model uses the NL3 effective interaction in the mean-field Lagrangian, and describes pairing correlations by the pairing part of the finite range Gogny interaction D1S. Two-neutron separation energies and ground-state quadrupole deformations that result from fully self-consistent RH+B solutions are compared with available experimental data. The model predicts a strong suppression of the spherical N=28 shell gap for neutron-rich nuclei: the 1f7/2⃗ fp core breaking results in deformed ground states. Shape coexistence is expected for neutron-rich Si, S, and Ar isotopes
Observational Constraints to the Evolution of Massive Stars
We consider some aspects of the evolution of massive stars which can only be
elucidated by means of "indirect" observations, i.e. measurements of the
effects of massive stars on their environments. We discuss in detail the early
evolution of massive stars formed in high metallicity regions as inferred from
studies of HII regions in external galaxies.Comment: 6 pages, 1 figure; Invited Paper presented at the Roma-Trieste
Workshop 1999 "The Chemical Evolution of the Milky Way: Stars versus
Clusters", Vulcano Island (ME, Italy), 20-24 September, 1999, eds. F.
Giovannelli & F. Matteucci, Kluwer-Holland (in press
New records of Ascomycota in the Northwestern Argentinean Yungas
We report new records for nine species of ascomycetes from the Yungas of northwestern Argentina. Capronia nigerrima, Capronia pulcherrima and Rosellinia dingleyae are new records for South America. Byssosphaeria rhodomphala, Camarops tubulina, Cercophora ambigua, Chaetosphaerella phaeostroma, Tubeufia, cylindrothecia are new species for Argentina, and Togninia minima is a new record for the biome.Fil: Gallo, María Cecilia Fátima. Fundación Miguel Lillo; Argentina. Universidad Nacional de Tucuman. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto Miguel Lillo; ArgentinaFil: Robledo, Gerardo Lucio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto Multidisciplinario de Biología Vegetal (p); ArgentinaFil: Romero, Andrea Irene. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Plantas Tóxicas y Medicinales, Metabolismo de Compuestos Sintéticos y Naturales - Hongos que Intervienen en la Degradación Biológica; ArgentinaFil: Catania, Myriam del V.. Fundación Miguel Lillo; Argentin
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