Abstract:
this article supports the idea that the differences and resemblances between rapanui and selk’nam in its relations with the "companies or exploitative societies" and the state of chile, in the context of the flow of persons and of capitals in the colonization process in the context of imperialism, allow a better comprehension of the detonator factors of its destinations as peoples. the central hypothesis is that the double convergence -of colonists and capital- in tierra del fuego does superfuously to the selk’nam (there is the discrepancy and the controversy on its destination), while in easter island only the capital few with which the indigenous population must be transformed in functional, in "colonists" and in "manpower". we explore then the answers of the native societies to this reality.

Abstract:
Este artículo sostiene que las diferencias y semejanzas acaecidas a Rapanui y Selk’nam en sus relaciones con las "compa ías o sociedades explotadoras" y el Estado de Chile, en el contexto de los fujos de personas y de capitales en los procesos de colonización en el contexto del imperialismo, permiten una mejor comprensión de los factores detonantes de sus destinos como pueblos. La hipótesis central es que la doble convergencia -de colonos y de capital- en Tierra del Fuego hace superfuo a los Selk’nam (de allí la discrepancia y la controversia sobre su destino), mientras que en Pascua sólo el capital fuyó con lo cual la población autóctona debió ser transformada en funcional, en "colonos" y en "mano de obra". Se explora entonces las respuestas de las sociedades originarias a esta realidad. This article supports the idea that the differences and resemblances between Rapanui and Selk’nam in its relations with the "companies or exploitative societies" and the State of Chile, in the context of the flow of persons and of capitals in the colonization process in the context of imperialism, allow a better comprehension of the detonator factors of its destinations as peoples. The central hypothesis is that the double convergence -of colonists and capital- in Tierra del Fuego does superfuously to the Selk’nam (there is the discrepancy and the controversy on its destination), while in Easter Island only the capital few with which the indigenous population must be transformed in functional, in "colonists" and in "manpower". We explore then the answers of the native societies to this reality.

Abstract:
An integrable version of the supersymmetric t-J model which is quantum group invariant as well as periodic is introduced and analysed in detail. The model is solved through the algebraic nested Bethe ansatz method.

Abstract:
To check the reliability of the Majorana representation of quantum spin systems, we use it to compute the ground state energy of an antiferromagnetic spin 1/2 chain to one loop order. We find a very small one loop correction of the mean field energy and a discrepancy of >100% compared to the Bethe Ansatz result. We conclude that a careful handling of the gauge degrees of freedom of this representation is crucial to get correct results.

Abstract:
The four center integrals needed in the Hartree Fock approximation and in TDDFT linear response are known to be difficult to calculate for orbitals of the Slater type or of finite range. We show that the interaction of pairs of products that do not mutually intersect may be replaced by the interaction of their moments, of which there are O(N). Only quadruplets of orbitals 'close' to one another need an explicit calculation and the total calculational effort therefore scales as O(N). We provide a new and concise proof of this "interaction by moments" property.

Abstract:
The production and the propagation of K+ and of K- mesons in heavy-ion collisions at beam energies of 1 to 2 AGeV have systematically been investigated with the Kaon Spectrometer KaoS at the SIS at the GSI. The ratio of the K+ production excitation function for Au+Au and for C+C reactions increases with decreasing beam energy, which is expected for a soft nuclear equation-of-state. At 1.5 AGeV a comprehensive study of the K+ and of the K- emission as a function of the size of the collision system, of the collision centrality, of the kaon energy, and of the polar emission angle has been performed. The K-/K+ ratio is found to be nearly constant as a function of the collision centrality. The spectral slopes and the polar emission patterns are different for K- and for K+. These observations indicate that K+ mesons decouple earlier from the reaction zone than K- mesons.

Abstract:
We transpose an idea of 't Hooft from its context of Yang and Mills' theory of strongly interacting quarks to that of strongly correlated electrons in transition metal oxides and show that a Hubbard model of N interacting electron species reduces, to leading orders in N, to a sum of almost planar diagrams. The resulting generating functional and integral equations are very similar to those of the FLEX approximation of Bickers and Scalapino. This adds the Hubbard model at large N to the list of solvable models of strongly correlated electrons. PACS Numbers: 71.27.+a 71.10.-w 71.10.Fd

Abstract:
It was observed previously that an SU(N) extension of the Hubbard model is dominated, at large N, by planar diagrams in the sense of 't Hooft, but the possibility of superconducting pairing got lost in this extrapolation. To allow for this possibility, we replace SU(N) by U(N,q), the unitary group in a vector space of quaternions. At the level of the free energy, the difference between the SU(N)and U(N,q) extrapolations appears only to first nonleading order in N.