981 research outputs found

    «Mapuche se es también en la waria (ciudad)». Disputas en torno a lo rural, lo urbano y lo indígena en la Argentina

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    El campo y la ciudad no constituyen meramente espacios físicos con determinadas características distintivas, sino a su vez espacios simbólicos histórica y hegemónicamente construidos como opuestos. En Argentina, dicho esquema ha dejado su impronta en los discursos y políticas estatales, tanto nacionales como provinciales, respecto de los pueblos indígenas2. Desde una perspectiva esencialista de las pertenencias e identidades, se ha instituido la vida rural como condición necesaria del «auténtico» indígena. No en vano, el primer y único Censo Indígena Nacional se implementó visitando sólo comunidades rurales en determinadas provincias del país. Aún gozando de fuerte consenso, tal reducción forma parte de procesos de construcción de hegemonía, entendida como un cuerpo de prácticas y significados continuamente renovado, recreado, defendido, resistido, desafiado y modificado. El presente trabajo se centra entonces en las disputas en torno a la relación entre lo rural, lo urbano y lo indígena en el contexto argentino. Partiendo del proceso de incorporación/ subordinación de los pueblos indígenas al Estado nacional, explora diversas producciones recientes de sujetos y agencias del pueblo mapuche que cuestionan, reformulan y/ o subvierten las representaciones instituidas

    Effective dynamics of the closed loop quantum cosmology

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    In this paper we study dynamics of the closed FRW model with holonomy corrections coming from loop quantum cosmology. We consider models with a scalar field and cosmological constant. In case of the models with cosmological constant and free scalar field, dynamics reduce to 2D system and analysis of solutions simplify. If only free scalar field is included then universe undergoes non-singular oscillations. For the model with cosmological constant, different behaviours are obtained depending on the value of Λ\Lambda. If the value of Λ\Lambda is sufficiently small, bouncing solutions with asymptotic de Sitter stages are obtained. However if the value of Λ\Lambda exceeds critical value Λc=3mPl22πγ321mPl2\Lambda_{\text{c}} =\frac{\sqrt{3}m^2_{\text{Pl}}}{2\pi\gamma^3} \simeq 21 m^2_{\text{Pl}} then solutions become oscillatory. Subsequently we study models with a massive scalar field. We find that this model possess generic inflationary attractors. In particular field, initially situated in the bottom of the potential, is driven up during the phase of quantum bounce. This subsequently leads to the phase of inflation. Finally we find that, comparing with the flat case, effects of curvature do not change qualitatively dynamics close to the phase of bounce. Possible effects of inverse volume corrections are also briefly discussed.Comment: 18 pages, 11 figure

    Beyond deficiency:Potential benefits of increased intakesof vitamin K for bone and vascular health

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    Vitamin K is wellknown for its role in the synthesisof a number of blood coagulationfactors.During recent years vitaminK-dependent proteins werediscovered to be of vital importancefor bone and vascular health.Recommendations for dietary vitaminK intake have been made onthe basis of the hepatic requirementsfor the synthesis of bloodcoagulation factors.Accumulatingevidence suggests that the requirementsfor other functions thanblood coagulation may be higher.This paper is the result of a closedworkshop (Paris,November 2002)in which a number of Europeanvitamin K experts reviewed theavailable data and formulated theirstandpoint with respect to recommendeddietary vitamin K intakeand the use of vitamin K-containingsupplements

    Closed FRW model in Loop Quantum Cosmology

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    The basic idea of the LQC applies to every spatially homogeneous cosmological model, however only the spatially flat (so called k=0k=0) case has been understood in detail in the literature thus far. In the closed (so called: k=1) case certain technical difficulties have been the obstacle that stopped the development. In this work the difficulties are overcome, and a new LQC model of the spatially closed, homogeneous, isotropic universe is constructed. The topology of the spacelike section of the universe is assumed to be that of SU(2) or SO(3). Surprisingly, according to the results achieved in this work, the two cases can be distinguished from each other just by the local properties of the quantum geometry of the universe. The quantum hamiltonian operator of the gravitational field takes the form of a difference operator, where the elementary step is the quantum of the 3-volume derived in the flat case by Ashtekar, Pawlowski and Singh. The mathematical properties of the operator are studied: it is essentially self-adjoint, bounded from above by 0, the 0 itself is not an eigenvalue, the eigenvectors form a basis. An estimate on the dimension of the spectral projection on any finite interval is provided.Comment: 19 pages, latex, no figures, high quality, nea

    Loop Quantum Cosmology corrections to inflationary models

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    In the recent years the quantization methods of Loop Quantum Gravity have been successfully applied to the homogeneous and isotropic Friedmann-Robertson-Walker space-times. The resulting theory, called Loop Quantum Cosmology (LQC), resolves the Big Bang singularity by replacing it with the Big Bounce. We argue that LQC generates also certain corrections to field theoretical inflationary scenarios. These corrections imply that in the LQC the effective sonic horizon becomes infinite at some point after the bounce and that the scale of the inflationary potential implied by the COBE normalisation increases. The evolution of scalar fields immediately after the Bounce becomes modified in an interesting way. We point out that one can use COBE normalisation to establish an upper bound on the quantum of length of LQG.Comment: 16 pages, 1 figure, plain Late

    The status of Quantum Geometry in the dynamical sector of Loop Quantum Cosmology

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    This letter is motivated by the recent papers by Dittrich and Thiemann and, respectively, by Rovelli discussing the status of Quantum Geometry in the dynamical sector of Loop Quantum Gravity. Since the papers consider model examples, we also study the issue in the case of an example, namely on the Loop Quantum Cosmology model of space-isotropic universe. We derive the Rovelli-Thiemann-Ditrich partial observables corresponding to the quantum geometry operators of LQC in both Hilbert spaces: the kinematical one and, respectively, the physical Hilbert space of solutions to the quantum constraints. We find, that Quantum Geometry can be used to characterize the physical solutions, and the operators of quantum geometry preserve many of their kinematical properties.Comment: Latex, 12 page
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