On the isospin dependence of the mean spin-orbit field in nuclei

By the use of the latest experimental data on the spectra of $^{133}$Sb and $^{131}$Sn and on the analysis of properties of other odd nuclei adjacent to doubly magic closed shells the isospin dependence of a mean spin-orbit potential is defined. Such a dependence received the explanation in the framework of different theoretical approaches.Comment: 52 pages, Revtex, no figure

Low momentum nucleon-nucleon potential and shell model effective interactions

A low momentum nucleon-nucleon (NN) potential V-low-k is derived from meson exhange potentials by integrating out the model dependent high momentum modes of V_NN. The smooth and approximately unique V-low-k is used as input for shell model calculations instead of the usual Brueckner G matrix. Such an approach eliminates the nuclear mass dependence of the input interaction one finds in the G matrix approach, allowing the same input interaction to be used in different nuclear regions. Shell model calculations of 18O, 134Te and 135I using the same input V-low-k have been performed. For cut-off momentum Lambda in the vicinity of 2 fm-1, our calculated low-lying spectra for these nuclei are in good agreement with experiments, and are weakly dependent on Lambda.Comment: 5 pages, 5 figure

Shell model half-lives for r-process N=82 nuclei

We have performed shell-model calculations of the half-lives and neutron-branching probabilities of the r-process waiting point nuclei at the magic neutron number N=82. These new calculations use a larger model space than previous shell model studies and an improved residual interaction which is adjusted to recent spectroscopic data around A=130. Our shell-model results give a good account of all experimentally known half-lives and $Q_\beta$-values for the N=82 r-process waiting point nuclei. Our half-life predictions for the N=82 nuclei with Z=42--46 agree well with recent estimates based in the energy-density functional method

Human occupation as a complex system

The present work justifies the change in theoretical approach required to use the concepts, principles and methods of artificial intelligence and computational science in order to deal with problems centered in social systems, such as studying the relation between human occupation and social stability and the validation of hypotheses about sociocybernetics strategies applied to governability. In order to model and study human occupation as a complex system, this document describes the autonomous components and the set of behaviors whose simultaneous and concurrent occurrence produce dynamical bifurcations (chaos) and emerging events in the Human Occupation, understood as a complex system between the triad: people - occupations - contexts, which expresses sensitive phenomena, impossible to be known completely and univocally. The components of the occupation are developed conceptually and relations of composition and condition of the given behaviors between these components are established, in order to establish human occupation as a complex system and in such a way that decision making and the prediction of occupational dynamics and behaviors in the individual and social levels can be modeled and simulated

Quadrupole-deformed and octupole collective bands in 228^{228}Ra

Spins and parities for collective states in $^{228}$Ra have been determined from conversion electron measurements with a mini-orange $\beta$-spectrometer. The fast-timing $\beta\gamma\gamma(t)$ method has been used to measure lifetimes of T$_{1/2}$=550(20) ps and 181(3) ps for the $2^{+}_{1}$ and $4^{+}_{1}$ members of the K=0$^{+}$ band, and T$_{1/2} \leqslant$ 7 ps and $\leqslant$ 6 ps for the $1^{-}_{1}$ and $3^{-}_1$ members of the K = $0^{-}$ band, respectively The quadrupole moments, $Q_{0}$ deduced from the B (E2; 2$_{1}^{+} \rightarrow 0_{1}^{+}$) and B (E2; 4$_{1}^{+} \rightarrow 2_1^{+}$) rates are in good agreement with the previously measured value and the systematics of the region. However, the B(E1) rates of $\geqslant$ 4 × 10$^{−4}$ e$^{2}$fm$^{2}$, which represent the first B(E1) measurements for this nucleus, are at least 25 times larger than the value previously suggested for $^{228}$Ra. The new results are consistent with the B(E1) rates recently measured for the neighbouring $^{227}$Ra and reveal octupole correlations in $^{228}$Ra

Developing nanotechnology in Latin America

This article investigates the development of nanotechnology in Latin America with a particular focus on Argentina, Brazil, Chile, and Uruguay. Based on data for nanotechnology research publications and patents and suggesting a framework for analyzing the development of R&D networks, we identify three potential strategies of nanotechnology research collaboration. Then, we seek to identify the balance of emphasis upon each of the three strategies by mapping the current research profile of those four countries. In general, we find that they are implementing policies and programs to develop nanotechnologies but differ in their collaboration strategies, institutional involvement, and level of development. On the other hand, we find that they coincide in having a modest industry participation in research and a low level of commercialization of nanotechnologies

When does the co-evolution of technology and science overturn into technoscience?

In this paper, the relations between science and technology, intervention and representation, the natural and the artificial are analysed on the background of the formation of modern science in the sixteenth century. Due to the fact that technique has been essential for modern science from its early beginning, modern science is characterised by a hybridisation of knowledge and intervention. The manipulation of nature in order to measure its properties has steadily increased until artificial things have been produced, such as laser beams, chemical compounds, elementary particles. Furthermore, the structural bracing of natural science, technological development, and industrial exploitation of nature go also back to the foundation of modern science. In order to strengthen the debate on technoscience against this background, the specific characteristics of technoscientific objects have to be clarified as have the specific characteristics of the social organisation of technoscience and its performance