Finite amplitude method for the quasi-particle-random-phase approximation

We present the finite amplitude method (FAM) for superfluid systems. A Hartree-Fock-Bogoliubov code may be transformed into a code of the quasi-particle-random-phase approximation (QRPA) with simple modifications. This technique has advantages over the conventional QRPA calculations, such as coding feasibility and computational cost. We perform the fully self-consistent linear-response calculation for a spherical neutron-rich nucleus 174Sn, modifying the HFBRAD code, to demonstrate the accuracy, feasibility, and usefulness of the FAM.Comment: 8 pages, 1 figur

Mediaciones tecnológicas: el entramado invisible del ciberespacio

Las nuevas tecnologías de la información y la comunicación (NTIC) abren un panorama más abarcador para el desarrollo social de los individuos, desde diferentes ámbitos sociales: educación, seguridad, economía, trabajo, esparcimiento, entre otros. Vivimos en una sociedad interconectada, traspasando barreras de tiempo y espacio; conviviendo entre certezas e incertidumbres, inmersos en un proceso de aceleración histórica, que tiene como elemento estable justa-mente “el cambio”. Hallamos nuevas maneras de conducta de las personas, nuevos modelos sociales y las tecnologías sustituyen a otras formas de intercambio tecnológico y social. Por ello es necesario conocer el papel que tiene la comunicación tecnológica en procesos de ajuste al cambio social y para ello se plantean los mecanismos de mediación que suceden en la sociedad y que determinan la capacidad de producción y reproducción de los sistemas sociales. En tiempos de Internet, de una cibercultura con ventajas y des-ventajas, ubicuidad, rapidez, simultaneidad, información producida al infinito y posibilidades de encontrar ilícitos también; planteamos una mediación tecnológica, como elemento para amalgamar estos temas, a la luz de los nuevos paradigmas sociales.The new information and communication technologies (ICT) open a wider range of possibilities for the social development of individuals from different social contexts: education, security, economy, work, leisure, among others. We live in an interconnected society, going beyond time and space boundaries; coexisting among certainties and uncertain-ties, and involved in a process of historical acceleration which has “change” as stable element. We find new behaviours in people, new social models, and technologies replace other ways of technological and social exchange. This is why it is necessary to know the role of technological communication in processes of adjustment to social change. We present the mediation mechanisms that take place in society and determine the production and reproduction capacity of the social systems. In times of the Internet, of a cyber-culture with advantages and disadvantages, ubiquity, speed, simultaneousness, information produced to the infinite and possibilities of finding illegalities as well; we pose a technological mediation, as an element to mix these topics, in light of the new social paradigms

Self-consistent description of nuclear photoabsorption cross sections

Several approaches to photonuclear reactions, based on the time-dependent density-functional theory, have been developed recently. The standard linearization leads to the random-phase approximation (RPA) or the quasiparticle-random-phase approximation (QRPA). We have developed a parallelized QRPA computer program for axially deformed nuclei. We also present a feasible approach to the (Q)RPA calculation, that is the finite amplitude method (FAM). We show results of photoabsorption cross sections for deformed nuclei using the QRPA and FAM calculations. Finally, the canonical-basis approach to the time-dependent Hartree-Fock-Bogoliubov method is presented, to demonstrate its feasibility and usefulness.Comment: 10 pages, 4 figures, Presented at Zakopane Conference of Nuclear Physics 201

Quantum calculation of vortices in the inner crust of neutron stars

We study, within a quantum mechanical framework based on self-consistent mean field theory, the interaction between a vortex and a nucleus immersed in a sea of free neutrons, a scenario representative of the inner crust of neutron stars. Quantal finite size effects force the vortex core outside the nucleus, influencing vortex pinning in an important way

Linear-response calculation in the time-dependent density functional theory

Linear response calculations based on the time-dependent density-functional theory are presented. Especially, we report results of the finite amplitude method which we have recently proposed as an alternative and feasible approach to the (quasiparticle-)random-phase approximation. Calculated properties of the giant resonances and low-energy E1 modes are discussed. We found a universal linear correlation between the low-energy E1 strength and the neutron skin thickness.Comment: 8 pages, 3 figures, Talk at The 11th International Symposium on Origin of Matter and Evolution of Galaxies (OMEG11), Nov. 14-17, 201

The Tangled Nature model as an evolving quasi-species model

We show that the Tangled Nature model can be interpreted as a general formulation of the quasi-species model by Eigen et al. in a frequency dependent fitness landscape. We present a detailed theoretical derivation of the mutation threshold, consistent with the simulation results, that provides a valuable insight into how the microscopic dynamics of the model determine the observed macroscopic phenomena published previously. The dynamics of the Tangled Nature model is defined on the microevolutionary time scale via reproduction, with heredity, variation, and natural selection. Each organism reproduces with a rate that is linked to the individuals' genetic sequence and depends on the composition of the population in genotype space. Thus the microevolutionary dynamics of the fitness landscape is regulated by, and regulates, the evolution of the species by means of the mutual interactions. At low mutation rate, the macro evolutionary pattern mimics the fossil data: periods of stasis, where the population is concentrated in a network of coexisting species, is interrupted by bursts of activity. As the mutation rate increases, the duration and the frequency of bursts increases. Eventually, when the mutation rate reaches a certain threshold, the population is spread evenly throughout the genotype space showing that natural selection only leads to multiple distinct species if adaptation is allowed time to cause fixation.Comment: Paper submitted to Journal of Physics A. 13 pages, 4 figure