The Immirzi Parameter as an Instanton Angle

The Barbero-Immirzi parameter is a one parameter quantization ambiguity underpinning the loop approach to quantum gravity that bears tantalizing similarities to the theta parameter of gauge theories such as Yang-Mills and QCD. Despite the apparent semblance, the Barbero-Immirzi field has resisted a direct topological interpretation along the same lines as the theta-parameter. Here we offer such an interpretation. Our approach begins from the perspective of Einstein-Cartan gravity as the symmetry broken phase of a de Sitter gauge theory. From this angle, just as in ordinary gauge theories, a theta-term emerges from the requirement that the vacuum is stable against quantum mechanical tunneling. The Immirzi parameter is then identified as a combination of Newton's constant, the cosmological constant, and the theta-parameter.Comment: 24 page

Gravity from a fermionic condensate of a gauge theory

The most prominent realization of gravity as a gauge theory similar to the gauge theories of the standard model comes from enlarging the gauge group from the Lorentz group to the de Sitter group. To regain ordinary Einstein-Cartan gravity the symmetry must be broken, which can be accomplished by known quasi-dynamic mechanisms. Motivated by symmetry breaking models in particle physics and condensed matter systems, we propose that the symmetry can naturally be broken by a homogenous and isotropic fermionic condensate of ordinary spinors. We demonstrate that the condensate is compatible with the Einstein-Cartan equations and can be imposed in a fully de Sitter invariant manner. This lends support, and provides a physically realistic mechanism for understanding gravity as a gauge theory with a spontaneously broken local de Sitter symmetry.Comment: 16 page

Generalized Chern-Simons Modified Gravity in First-Order Formalism

We propose a generalization of Chern-Simons (CS) modified gravity in first-order formalism. CS modified gravity action has a term that comes from the chiral anomaly which is Pontryagin invariant. First-order CS modified gravity is a torsional theory and in a space-time with torsion the chiral anomaly includes a torsional topological term called Nieh-Yan invariant. We generalize the CS modified gravity by adding the Nieh-Yan term to the action and find the effective theory. We compare the generalized theory with the first-order CS modified gravity and comment on the similarities and differences.Comment: 8 pages, an author added, new paragraphs, comments and references added, published in Gen. Relativ. Gravi

Giant Prolactinoma Embedded by Pseudoaneurysm of the Cavernous Carotid Artery Treated with a Tailored Therapeutic Scheme

The coexistence of intracranial aneurysm (IA) is generally thought to be highest in patients with pituitary adenomas (PAs). Different mechanisms may play a role in aneurysm formation, but whether the PA contributes to aneurysm formation is still unclear. In the literature, there are numerous reported cases of this association; however, the analyses of the characteristics of PAs, aneurysms, and treatment management are rare and limited to a restricted number of case reports. We report a rare case of an embedded aneurysm in a macroprolactinoma treated with therapeutic management tailored to the clinical, neurological, and radiological characteristics of the patient. To select the best treatment, we reviewed the literature and reported the only cases in which the radiological characteristics of aneurysms, PAs, therapeutic management, and patient outcome are described. We aimed to understand what are the variables that determine the best therapeutic management with the best possible outcome. The presence of a large pseudoaneurysm of the internal carotid artery completely embedded in a giant macroprolactinoma is rare and needs a tailored treatment strategy. The importance of the preoperative knowledge of asymptomatic IA coexisting with PA can avoid accidental rupture of the aneurysm during surgical resection and may lead to planning the best treatment. A high degree of suspicion for an associated aneurysm is needed, and if magnetic resonance imaging shows some atypical features, digital subtraction angiography must be performed prior to contemplating any intervention to avoid iatrogenic aneurysmal rupture. Our multimodal approach with the first-line therapy of low-dose cabergoline to obtain prolactin normalization with minimum risks of aneurysms rupture and subsequent endovascular treatment with flow diverter has not been described elsewhere to our knowledge. In the cases, we suggest adopting a tailored low-dose cabergoline therapy scheme to avoid rupture during cytoreduction and initiate a close neuroradiological follow-up program

E-Voting in an ubicomp world: trust, privacy, and social implications

The advances made in technology have unchained the user from the desktop into interactions where access is anywhere, anytime. In addition, the introduction of ubiquitous computing (ubicomp) will see further changes in how we interact with technology and also socially. Ubicomp evokes a near future in which humans will be surrounded by “always-on,” unobtrusive, interconnected intelligent objects where information is exchanged seamlessly. This seamless exchange of information has vast social implications, in particular the protection and management of personal information. This research project investigates the concepts of trust and privacy issues specifically related to the exchange of e-voting information when using a ubicomp type system

First data on obsidian provenance at a formative site in Santa Rosa de los Pastos Grandes, Puna of Salta, Argentina

Los estudios de procedencia de materias primas permiten de algún modo orientar las investigaciones sobre interacciones sociales. Las obsidianas constituyen una materia prima ideal ya que, desde el punto de vista de su composición química, cada fuente es altamente homogénea internamente, pero significativamen­te distintas entre ellas; y aunque los artefactos confeccionados en obsidianas tengan una amplia dispersión, las fuentes están acotadas geográficamente. Este trabajo pretende ser un aporte a la información sobre las dinámicas respecto a las esferas de interacción en la Puna argentina en momentos de producción inicial de alimentos (ca. 2500- 1500 AP). En primera instancia, se presentan los resultados del análisis por XRF sobre las obsidianas provenientes de excavaciones arqueológicas de Quebrada Alta en Santa Rosa de los Pastos Grandes, en la Puna de Salta. Luego se caracterizan y discuten los contextos de hallazgo.Analysis of raw material sources may guide research of social interaction. Obsidians constitute a good material since they are internally highly homogeneous in its chemical composition, while meaningfully different between sources, and though obsidian artifacts may have a wide scattered pattern, sources are geographically constrained. This paper is a contribution to the understanding of the interaction networks and their dynamics in the Puna of Argentina during early Formative period (ca. 2500- 1500 BP). We first present the results of XRF analysis carried on obsidian artifacts from Quebrada Alta in Santa Rosa de los Pastos Grandes, in Salta province’s Puna. Then we discuss this evidence within the frame of social interaction networks

First data on obsidian provenance at a Formative site in santa rosa de los pastos Grandes, puna oF salta, arGentina

Los estudios de procedencia de materias primas permiten de algún modo orientar las investigaciones sobre interacciones sociales. Las obsidianas constituyen una materia prima ideal ya que, desde el punto de vista de su composición química, cada fuente es altamente homogénea internamente, pero significativamen­te distintas entre ellas; y aunque los artefactos confeccionados en obsidianas tengan una amplia dispersión, las fuentes están acotadas geográficamente. Este trabajo pretende ser un aporte a la información sobre las dinámicas respecto a las esferas de interacción en la Puna argentina en momentos de producción inicial de alimentos (ca. 2500- 1500 AP). En primera instancia, se presentan los resultados del análisis por XRF sobre las obsidianas provenientes de excavaciones arqueológicas de Quebrada Alta en Santa Rosa de los Pastos Grandes, en la Puna de Salta. Luego se caracterizan y discuten los contextos de hallazgo.Analysis of raw material sources may guide research of social interaction. Obsidians constitute a good material since they are internally highly homogeneous in its chemical composition, while meaningfully different between sources, and though obsidian artifacts may have a wide scattered pattern, sources are geographically constrained. This paper is a contribution to the understanding of the interaction networks and their dynamics in the Puna of Argentina during early Formative period (ca. 2500- 1500 BP). We first present the results of XRF analysis carried on obsidian artifacts from Quebrada Alta in Santa Rosa de los Pastos Grandes, in Salta province’s Puna. Then we discuss this evidence within the frame of social interaction networks.Fil: Mercuri, Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Filosofía y Letras. Instituto de Arqueología; ArgentinaFil: Glascock, Michael D.. University of Missouri; Estados Unido

First data on obsidian provenance at a Formative site in santa rosa de los pastos Grandes, puna oF salta, arGentina

Los estudios de procedencia de materias primas permiten de algún modo orientar las investigaciones sobre interacciones sociales. Las obsidianas constituyen una materia prima ideal ya que, desde el punto de vista de su composición química, cada fuente es altamente homogénea internamente, pero significativamen­te distintas entre ellas; y aunque los artefactos confeccionados en obsidianas tengan una amplia dispersión, las fuentes están acotadas geográficamente. Este trabajo pretende ser un aporte a la información sobre las dinámicas respecto a las esferas de interacción en la Puna argentina en momentos de producción inicial de alimentos (ca. 2500- 1500 AP). En primera instancia, se presentan los resultados del análisis por XRF sobre las obsidianas provenientes de excavaciones arqueológicas de Quebrada Alta en Santa Rosa de los Pastos Grandes, en la Puna de Salta. Luego se caracterizan y discuten los contextos de hallazgo.Analysis of raw material sources may guide research of social interaction. Obsidians constitute a good material since they are internally highly homogeneous in its chemical composition, while meaningfully different between sources, and though obsidian artifacts may have a wide scattered pattern, sources are geographically constrained. This paper is a contribution to the understanding of the interaction networks and their dynamics in the Puna of Argentina during early Formative period (ca. 2500- 1500 BP). We first present the results of XRF analysis carried on obsidian artifacts from Quebrada Alta in Santa Rosa de los Pastos Grandes, in Salta province’s Puna. Then we discuss this evidence within the frame of social interaction networks.Fil: Mercuri, Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Filosofía y Letras. Instituto de Arqueología; ArgentinaFil: Glascock, Michael D.. University of Missouri; Estados Unido

Generating functional for the gravitational field: implementation of an evolutionary quantum dynamics

We provide a generating functional for the gravitational field, associated to the relaxation of the primary constraints as extended to the quantum sector. This requirement of the theory, relies on the assumption that a suitable time variable exist, when taking the T-products of the dynamical variables. More precisely, we start from the gravitational field equations written in the Hamiltonian formalism and expressed via Misner-like variables; hence we construct the equation to which the T-products of the dynamical variables obey and transform this paradigm in terms of the generating functional, as taken on the theory phase-space. We show how the relaxation of the primary constraints (which correspond to break down the invariance of the quantum theory under the 4-diffeomorphisms) is summarized by a free functional taken on the Lagrangian multipliers, accounting for such constraints in the classical theory. The issue of our analysis is equivalent to a Gupta-Bleuler approach on the quantum implementation of all the gravitational constraints; in fact, in the limit of small $\hbar$, the quantum dynamics is described by a Schr\"odinger equation, as soon as the mean values of the momenta, associated to the lapse function and the shift vector, are not vanishing. Finally we show how, in the classical limit, the evolutionary quantum gravity reduces to General Relativity in the presence of an Eckart fluid, which corresponds to the classical counterpart of the physical clock, introduced in the quantum theory.Comment: 23 pages, no figures, to appear on International Journal of Modern Physics