Para una fundamentación dialéctica de la liberación latinoamericana

Ningun

Crisis de la Iglesia latinoamericana y situación del pensador cristiano en Argentina

Ningun

Structure of the vacuum states in the presence of isovector and isoscalar pairing correlations

The long standing problem of proton-neutron pairing and, in particular, the limitations imposed on the solutions by the available symmetries, is revisited. We look for solutions with non-vanishing expectation values of the proton, the neutron and the isoscalar gaps. For an equal number of protons and neutrons we find two solutions where the absolute values of proton and neutrons gaps are equal but have the same or opposite sign. The behavior and structure of these solutions differ for spin saturated (single l-shell) and spin unsaturared systems (single j-shell). In the former case the BCS results are checked against an exact calculation.Comment: 19 pages, 5 postscript figure

Resistindo ao desenvolvimento neocolonial: a luta do povo de Andalgalá contra projetos megamineiros

A América Latina vem experimentando uma nova era de declarada fé dos governos no mito do desenvolvimento, em articulação com a expansão de políticas extrativistas exportadoras em um contexto de renovada dependência. A face mais dramática do extrativismo na região tem sido a crescente presença de corporações mineiras transnacionais apoiadas por governos nacionais e regionais e por instituições internacionais financeiras e de apoio ao desenvolvimento, e intensamente resistidas por movimentos sociais populares. Neste artigo apresentamos o caso de Andalgalá (uma pequena cidade na Província de Catamarca, na Argentina) e as lutas do povo contra corporações mineiras transnacionais e seus aliados. Na tradição da Filosofia da Libertação e do método ana-dialético de Dussel, nos engajamos com o que tem sido denominado "comunidades argentinas do NÃO", expressando sua oposição a formas neocoloniais de desenvolvimento e gestão. Neste artigo estamos especificamente interessados em compreender como dois dispositivos gerencialistas usados pelas corporações mineiras, responsabilidade social corporativa (RSC) e pactos de governança, impactam a luta do povo. Acima de tudo, este artigo oferece instantâneos de batalhas na linha de frente do extrativismo. Esperamos ter dado voz àquelas pessoas que normalmente não são ouvidas, criando um espaço para suas visões sobre um tipo diferente de desenvolvimento.</jats:p

An Algebraic Pairing Model with Sp(4) Symmetry and its Deformation

A fermion realization of the compact symplectic sp(4) algebra provides a natural framework for studying isovector pairing correlations in nuclei. While these correlations manifest themselves most clearly in the binding energies of 0^+ ground states, they also have a large effect on the energies of excited states, including especially excited 0^+ states. In this article we consider non-deformed as well as deformed algebraic descriptions of pairing through the reductions of sp_{(q)}(4) to different realizations of u_{(q)}(2) for single-j and multi-j orbitals. The model yields a classification scheme for completely paired 0^{+} states of even-even and odd-odd nuclei in the 1d_{3/2}, 1f_{7/2}, and 1f_{5/2}2p_{1/2}2p_{3/2}1g_{9/2} shells. Phenomenological non-deformed and deformed isospin-breaking Hamiltonians are expressed in terms of the generators of the dynamical symmetry groups Sp(4) and Sp_{q}(4). These Hamiltonians are related to the most general microscopic pairing problem, including isovector pairing and isoscalar proton-neutron interaction along with non-linear interaction in the deformed extension. In both the non-deformed and deformed cases the eigenvalues of the Hamiltonian are fit to the relevant Coulomb corrected experimental 0^{+} energies and this, in turn, allows us to estimate the interaction strength parameters, to investigate isovector-pairing properties and symmetries breaking, and to predict the corresponding energies. While the non-deformed theory yields results that are comparable to other theories for light nuclei, the deformed extension, which takes into account higher-order interactions between the particles, gives a better fit to the data. The multi-shell applications of the model provide for reasonable predictions of energies of exotic nuclei.Comment: 19 pages, 5 figures minor changes; improvements to achieve a better and clearer presentation of our messages and idea

Gamow Shell Model Description of Weakly Bound Nuclei and Unbound Nuclear States

We present the study of weakly bound, neutron-rich nuclei using the nuclear shell model employing the complex Berggren ensemble representing the bound single-particle states, unbound Gamow states, and the non-resonant continuum. In the proposed Gamow Shell Model, the Hamiltonian consists of a one-body finite depth (Woods-Saxon) potential and a residual two-body interaction. We discuss the basic ingredients of the Gamow Shell Model. The formalism is illustrated by calculations involving {\it several} valence neutrons outside the double-magic core: $^{6-10}$He and $^{18-22}$O.Comment: 19 pages, 20 encapsulated PostScript figure

Local Density Approximation for proton-neutron pairing correlations. I. Formalism

In the present study we generalize the self-consistent Hartree-Fock-Bogoliubov (HFB) theory formulated in the coordinate space to the case which incorporates an arbitrary mixing between protons and neutrons in the particle-hole (p-h) and particle-particle (p-p or pairing) channels. We define the HFB density matrices, discuss their spin-isospin structure, and construct the most general energy density functional that is quadratic in local densities. The consequences of the local gauge invariance are discussed and the particular case of the Skyrme energy density functional is studied. By varying the total energy with respect to the density matrices the self-consistent one-body HFB Hamiltonian is obtained and the structure of the resulting mean fields is shown. The consequences of the time-reversal symmetry, charge invariance, and proton-neutron symmetry are summarized. The complete list of expressions required to calculate total energy is presented.Comment: 22 RevTeX page

Transnational Perspectives on Black Subjectivity

In this article, five black researchers bring their insights into conversation about meanings of blackness in contemporary Australia, Jamaica, South Africa, the United Kingdom and the United States of America. We critically interrogate blackness transnationally, but also within the historical contexts of our work and lived experiences. Situated within critical race studies, we draw on multiple theoretical frameworks that seek to preserve the complexity of blackness, its meanings and implications. We examine what it means to be made black by history and context, and explore the im/possibilities of transcending such subjectification. In so doing, we engage blackness and its relationality to whiteness; the historical, temporal and spatial dimensions of what it means to be black; the embodied, affective and psychical components of black subjectivity; and the continued marketization of blackness today. The article concludes by reflecting on the emancipatory promise of continued engagement with black subjectivity, but with critical reflexivity, so as to avoid the pitfalls of engaging blackness as a static and essentialised mode of subjectivity

Diversities, affinities and diasporas: a southern lens and methodology for understanding multilingualisms

We frame multilingualisms through a growing interest in a linguistics and sociology of the ‘south’ and acknowledge earlier contributions of linguists in Africa, the Américas and Asia who have engaged with human mobility, linguistic contact and consequential ecologies that alter over time and space. Recently, conversations of multilingualism have drifted in two directions. Southern conversations have become intertwined with ‘decolonial theory’, and with ‘southern’ theory, thinking and epistemologies. In these, ‘southern’ is regarded as a metaphor for marginality, coloniality and entanglements of the geopolitical north and south. Northern debates that receive traction appear to focus on recent ‘re-awakenings’ in Europe and North America that mis-remember southern experiences of linguistic diversity. We provide a contextual backdrop for articles in this issue that illustrate intelligences of multilingualisms and the linguistic citizenship of southern people. In these, southern multilingualisms are revealed as phenomena, rather than as a phenomenon defined usually in English. The intention is to suggest a third direction of mutual advantage in rethinking the social imaginary in relation to communality, entanglements and interconnectivities of both South and North