América Latina entre dos Sarajevos

El autor pone énfasis en las constantes históricas -crisis estructurales permanentes- que a lo largo del siglo xx han caracterizado el desarrollo de América Latina. Dichas constantes han sido alimentadas por el afán de imitación que los países latinoamericanos han hecho de los modelos de desarrollo extremos. Ello ha ocasionado que la anhelada incorporación de estas naciones al ámbito internacional se haya dado de manera "subordinada". A partir de esta premisa, el autor va analizando los cambios que en el nivel internacional se han suscitado a fines del siglo y las consecuencias que los mismos han acarreado hacia el interior de los países periféricos. Asimismo, discute el nuevo sistema internacional, caracterizado por múltiples cambios en lo político, lo económico y lo tecnológico; es decir, un sistema basado en la "integración transnacional" o "globalizante".The author places an emphasis on the historical constants -permanent structural crises- that, throughout the 20th century, have characterized Latin American development. These constants have been fed by the imitative desire that Latin American countries have had for extemal developmental models. The outcome has been such, that these nation's longing to incorpórate to the intemational environment, have produced a "subordínate" manner. Starting from this premise, the author analyzes the changes that, on an intemational level, have taken place at the end of the century and the consequences they have produced inside the peripheral countries. Also, the author discusses the new intemational order, characterized by changes in politics, economics and technology; i.e., a system based on the "transnational integration" or "globalizing"

Flavour physics of the RS model with KK masses reachable at LHC

The version of the higher-dimensional Randall-Sundrum (RS) model with matter in the bulk, which addresses the gauge hierarchy problem, has additional attractive features. In particular, it provides an intrinsic geometrical mechanism that can explain the origin of the large mass hierarchies among the Standard Model fermions. Within this context, a good solution for the gauge hierarchy problem corresponds to low masses for the Kaluza-Klein (KK) excitations of the gauge bosons. Some scenarios have been proposed in order to render these low masses (down to a few TeV) consistent with precision electroweak measurements. Here, we give specific and complete realizations of this RS version with small KK masses, down to 1 TeV, which are consistent with the entire structure of the fermions in flavour space: (1) all the last experimental data on quark/lepton masses and mixing angles (including massive neutrinos of Dirac type) are reproduced, (2) flavour changing neutral current constraints are satisfied and (3) the effective suppression scales of non-renormalizable interactions (in the physical basis) are within the bounds set by low energy flavour phenomenology. Our result, on the possibility of having KK gauge boson modes as light as a few TeV, constitutes one of the first theoretical motivations for experimental searches of direct signatures at the LHC collider, of this interesting version of the RS model which accommodates fermion masses.Comment: 27 pages, Latex file. References and comments adde

Proceso político y movimiento obrero en América Latina

Entre el triunfo de la Revolución Socialista Cubana, el ascenso al gobierno de la Unión Popular en Chile y el triunfo de la Revoluión Sandinista de Nicaragua, el fenómeno latinoamericano de mayor peso ha sido el de la crisis política en que tienen marco los movimientos de masas organizadas. Su consecuencia inmediata ha sido el agravamiento y mayor complejidad de los problemas del movimiento obrero en el Área. Ramón Martínez Escamilla, Marcos Kaplan, José María Calderón, Sergio Bagú, Julio Godio, Julio le Riverend e Irma Manrique ofrecen en Proceso político y movimiento obrero en América Latina un aporte fundamental a la reinterpretación que exige en nuestro tiempo tal estado de cosas

Successful Yukawa structures in Warped Extra Dimensions

For a RS model, with SM fields in the bulk and the Higgs boson on the TeV-brane, we suggest two specific structures for the Yukawa couplings, one based on a permutation symmetry and the other on the Universal Strength of Yukawa couplings hypothesis (USY). In USY, all Yukawa couplings have equal strength and the difference in the Yukawa structure lies in some complex phase. In both scenarios, all Yukawa couplings are of the same order of magnitude. Thus, the main features of the fermion hierarchies are explained through the RS geometrical mechanism, and not because some Yukawa coupling is extremely small. We find that the RS model is particularly appropriate to incorporate the suggested Yukawa configurations. Indeed, the RS geometrical mechanism of fermion locations along the extra dimension, combined with the two Yukawa scenarios, reproduces all the present experimental data on fermion masses and mixing angles. It is quite remarkable that in the USY case, only two complex phases of definite value +-Pi/2 are sufficient to generate the known neutrino mass differences, while at same time, permitting large leptonic mixing in agreement with experiment.Comment: 11 page

Selenomethionine administration decreases the oxidative stress induced by post mortem ischemia in the heart, liver and kidneys of rats

Selenium is an essential element in human and animal metabolism integrated into the catalytic site of glutathione peroxidase (GPX1), an antioxidant enzyme that protects cells from damage caused by reactive oxygen species (ROS). Oxidative stress refers the imbalance between ROS and antioxidant defense systems. It generates alterations of DNA, proteins and lipid peroxidation. The imbalance occurs particularly during ischemia and lack of postmortem perfusion. This mechanism is of relevance in transplant organs, affecting their survival. The aim of this research is to evaluate the effect of seleno-methionine (SeMet) as a protective agent against postmortem ischemia injury in transplant organs. Wistar rats were orally administered with SeMet. After sacrifice, liver, heart and kidney samples were collected at different postmortem intervals (PMIs). SeMet administration produced a significant increase of Se concentration in the liver (65%, p < 0.001), heart (40%, p < 0.01) and kidneys (45%, p < 0.05). Levels of the oxidative stress marker malondialdehyde (MDA) decreased significantly compared to control in the heart (0.21 ± 0.04 vs. 0.12 ± 0.02 mmol g−1) and kidneys (0.41 ± 0.02 vs. 0.24 ± 0.03 mmol g−1) in a PMI of 1–12 h (p < 0.01). After SeMet administration for 21 days, a significant increase in GPX1 activity was observed in the liver (80%, p < 0.001), kidneys (74%, p < 0.01) and heart (35%, p < 0.05). SeMet administration to rats significantly decreased the oxidative stress in the heart, liver and kidneys of rats generated by postmortem ischemia.Fil: Hasuoka, Paul Emir. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; ArgentinaFil: Pérez Iglesias, Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; ArgentinaFil: Teves, Mauricio Roberto. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia; ArgentinaFil: Kaplan, Marcos Manuel. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ferrúa, Nelson Hugo. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia; ArgentinaFil: Pacheco, Pablo Hugo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; Argentin

Fredholm methods for billiard eigenfunctions in the coherent state representation

We obtain a semiclassical expression for the projector onto eigenfunctions by means of the Fredholm theory. We express the projector in the coherent state basis, thus obtaining the semiclassical Husimi representation of the stadium eigenfunctions, which is written in terms of classical invariants: periodic points, their monodromy matrices and Maslov indices.Comment: 12 pages, 10 figures. Submitted to Phys. Rev. E. Comments or questions to [email protected]

On the chains of star complexes and superclouds in spiral arms

The relation is studied between occurrence of a regular chain of star complexes and superclouds in a spiral arm, and other properties of the latter. A regular string of star complexes is located in the north-western arm of M31; they have about the same size 0.6 kpc with spacing of 1.1 kpc. Within the same arm segment the regular magnetic field with the wavelength of 2.3 kpc was found by Beck et al. (1989). We noted that this wavelength is twice as large as the spacing between complexes and suggested that they were formed in result of magneto-gravitational instability developed along the arm. In this NW arm, star complexes are located inside the gas-dust lane, whilst in the south-western arm of M31 the gas-dust lane is upstream of the bright and uniform stellar arm. Earlier, evidence for the age gradient has been found in the SW arm. All these are signatures of a spiral shock, which may be associated with unusually large (for M31) pitch-angle of this SW arm segment. Such a shock may prevent the formation of the regular magnetic field, which might explain the absence of star complexes there. Anti-correlation between shock wave signatures and presence of star complexes is observed in spiral arms of a few other galaxies. Regular chains of star complexes and superclouds in spiral arms are rare, which may imply that a rather specific mechanism is involved in their formation, and the most probable one is the Parker-Jeans instability. The spiral pattern of our Galaxy is briefly discussed; it may be of M101 type in the outer parts. The regular bi-modal spacing of HI superclouds is found in Carina and Cygnus (Outer) arms, which may be an indirect evidence for the regular magnetic field along these arms.Comment: 20 pages, 12 figures, accepted for publication in MNRA