The reform of Welfare Regimes in Costa Rica, Chile, Argentina, Brazil and Uruguay

The aim of this article is to analyze the social policy in Latin America in a context of emerging welfare states. To understand the changes one takes into consideration the theories about institutional reform and the transformations produced in the XX century and the beginning of the XXI to substitute a social security regime mainly based on segmentation of benefi ts and on programs to fi ght poverty by another with an institutional and redistributive nature. The paper pays attention in particular to the path of the most developed welfare states of Latin America: Costa Rica, Chile, Argentina, Brasil y Uruguay.

Equilibrium polymerization of cyclic carbonate oligomers. III. Chain branching and the gel transition

Ring-opening polymerization of cyclic polycarbonate oligomers, where monofunctional active sites act on difunctional monomers to produce an equilibrium distribution of rings and chains, leads to a "living polymer." Monte Carlo simulations [two-dimensional (2D) and three-dimensional (3D)] of the effects of single [J. Chem. Phys. 115, 3895 (2001)] and multiple active sites [J. Chem. Phys. 116, 7724 (2002)] are extended here to trifunctional active sites that lead to branching. Low concentrations of trifunctional particles c(3) reduce the degree of polymerization significantly in 2D, and higher concentrations (up to 32%) lead to further large changes in the phase diagram. Gel formation is observed at high total density and sizable c(3) as a continuous transition similar to percolation. Polymer and gel are much more stable in 3D than in 2D, and both the total density and the value of c(3) required to produce high molecular weight aggregates are reduced significantly. The degree of polymerization in high-density 3D systems is increased by the addition of trifunctional monomers and reduced slightly at low densities and low c(3). The presence of branching makes equilibrium states more sensitive (in 2D and 3D) to changes in temperature T. The stabilities of polymer and gel are enhanced by increasing T, and-for sufficiently high values of c(3)-there is a reversible polymer-gel transformation at a density-dependent floor temperature. (C) 2002 American Institute of Physics.

High-pressure deformation mechanism in scolecite: A combined computational-experimental study

Pressure-induced structural modifications in scolecite were studied by means of in situ synchrotron X-ray powder diffraction and density functional computations. The experimental cell parameters were refined up to 8.5 GPa. Discontinuities in the slope of the unit-cell parameters vs. pressure dependence were observed; as a consequence, an increase in the slope of the linear pressure-volume dependence is observed at about 6 GPa, suggesting an enhanced compressibility at higher pressures. Weakening and broadening of the diffraction peaks reveals increasing structural disorder with pressure, preventing refinement of the lattice parameters above 8.5 GPa. Diffraction patterns collected during decompression show that the disorder is irreversible. Atomic coordinates within unit cells of different dimensions were determined by means of Car-Parrinello simulations. The discontinuous rise in compressibility at about 6 GPa is reproduced by the computation, allowing us to attribute it to re-organization of the hydrogen bonding network, with the formation of water dimers. Moreover we found that, with increasing pressure, the tetrahedral chains parallel to c rotate along their elongation axis and display an increasing twisting along a direction perpendicular to c. At the same time, we observed the compression of the channels. We discuss the modification of the Ca polyhedra under pressure, and the increase in coordination number (from 4 to 5) of one of the two Al atoms, resulting from the approach of a water molecule. We speculate that this last transformation triggers the irreversible disordering of the system.

The regulation and role of osteopontin in malignant transformation and cancer.

Osteopontin (OPN) is a predominantly secreted extracellular matrix glycophosphoprotein which binds to alpha v-containing integrins and has an important role in malignant cell attachment and invasion. High OPN expression in the primary tumor is associated with early metastasis and poor outcome in human breast and other cancers. Forced OPN overexpression in benign cells may induce neoplastic-like cell behaviour including increased attachment and invasion in vitro as well as the ability to metastasize in vivo. Conversely, OPN inhibition by antisense cDNA impedes cell growth and tumor forming capacity. OPN is not mutationally activated in cancer but its expression is regulated by Wnt/Tcf signaling, steroid receptors, growth factors, ras, Ets and AP-1 transcription factors. Presumably these factors are implicated in induction of OPN overexpression in cancer. Greater understanding of the role of OPN in neoplastic change and its transcriptional regulation may enable development of novel cancer treatment strategies

Non-agrocultural co-peratives and economy transformation in Cuba: politic processes and strategies

Contribution of co-operatives has been demonstrated since the 1970s as the main development line in agricultural production in Cuba. In contrast, there has been a late recognition of urban co-operatives, even if the need of transformations based on the realization of property in different territorial scenarios had been identified. The article analyses the reform processes launched since the first decade of the 21st century focusing on the nature of the initiatives fostering formation and promotion of nonagricultural co-operatives including follow up of their performance. The potential and limitations of the recent experiences are examined in order to reflect on the organizational processes and transformations from the point of view of their members. To conclude, some questions are posed about whether these co-operatives are capable of avoiding the impact of earlier employment circumstances and of developing strategies aimed at reinforcing voluntary membership and autonomy on which they are founded.