Abstract We perform an extension of the relation between the Nambu-Goto action and classical rebits. Of course, the Cayley hyperdeterminant is the key mathematical tool in such generalization. Using the Wick rotation, we find that in four dimensions such a relation can be established no only with the signature (2+2) but also with any signature. We generalize our result to a curved space-time of (2 2n +2 2n )-dimensions and (2 2n+1 +2 2n+1 )-dimensions.

Abstract We discuss different aspects of a possible link between the (1+1)-matrix-brane system with qubit theory and non-compact Hopf maps. In these scenarios, the (2+2)-signature plays an important role. We argue that such links may shed some light on the (2+2)-dimensional sector of a (2+10)-dimensional target background.

We assume gravity in a d-dimensional manifold M and consider a splitting of the form M = Mp × Mq, with d = p + q. The most general two-block metric associated with Mp and Mq is used to derive the corresponding Einstein-Hilbert action S. We focus on the special case of two distinct conformal factors ψ and φ (ψ for the metric in Mp and φ for the metric in Mq), and we write the action S in the form S = Sp+Sq, where Sp and Sq are actions associated with Mp and Mq, respectively. We show that a simplified action is obtained precisely when ip = p-1. In this case, we find that under the duality transformation φ ↔ φ-1, the action Sp for the Mp-space or the action Sq for the Mq-space remain invariant, but not both. This result establishes an analogy between Farkas property in oriented matroid theory and duality in general relativity. Furthermore, we argue that our approach can be used in several physical scenarios such as 2t physics and cosmology.

We establish a connection between oriented matroid theory and loop quantum gravity in (2+2) (two time and two space dimensions) and 8-dimensions. We start by observing that supersymmetry implies that the structure constants of the real numbers, complex numbers, quaternions and octonions can be identified with the chirotope concept. This means, among other things, that normed divisions algebras, which are only possible in 1,2, 4 or 8-dimensions, are linked to oriented matroid theory. Therefore, we argue that the possibility for developing loop quantum gravity in 8-dimensions must be taken as important alternative. Moreover, we show that in 4-dimensions, loop quantum gravity theories in the (1+3) or (0+4) signatures are not the only possibilities. In fact, we show that loop quantum gravity associated with the (2+2)-signature may also be an interesting physical structure.

We find a link between oriented matroid theory and 2d gravity with torsion. Our considerations may be useful in the context of noncommutative phase space in a target spacetime of signature (2+2) and in a possible theory of gravity ramification.

Streptococcus pyogenes causes a variety of common human diseases, including pharyngitis, scarlet fever and impetigo. Nevertheless, the past decades have witnessed a worldwide resurgence in invasive disease and streptococcal toxic shock syndrome (STSS). The objective of the present study is to evaluate the genetic diversity, virulence gene distribution (spe, sme and ssa genes) and susceptibility pattern of 10 S. pyogenes isolates causing invasive disease and STSS. The isolates were recovered from blood cultures of hospitalized patients at Hospital Santamarina and Nueva Clínica Chacabuco, Tandil, Buenos Aires, Argentina between 12/2000-04/2005. Two pulse field gel electrophoretic patterns predominated. The most frequent one included 5 characteristic isolates of emm1-T1 type, toxin gene profile speA, speB, speF, speG and smeZ. The second pattern included 2 characteristic isolates of emm3-TNT type (speB, speF, speG). The other 3 isolates corresponded to types emm49-TNT (speB, speC, speF, speG), emm75-T25 (speB, speF, speG) and emm83-TNT (speB, speF, speG, ssa, smeZ). All isolates were susceptible to penicillin, cefotaxime, erythromycin, clindamycin, chloramphenicol, tetracycline and rifampicin. The data from the present study demonstrated genetic diversity among the strains. Types emm1 and emm3 were prevalent in invasive disease. The empirical treatment with the combination of penicillin and clindamicin is still valid.

Streptococcus pyogenes es el agente causal de varias enfermedades comunes entre las que se incluyen la faringoamigdalitis, la escarlatina y el impétigo. Sin embargo, en las últimas décadas se ha registrado mundialmente un resurgimiento de casos de enfermedad invasora y síndrome de shock tóxico estreptocócico (SSTE). El propósito del presente trabajo fue estudiar la diversidad genética, los factores de virulencia (genes spe, sme, ssa) y la sensibilidad a los antibióticos de 10 cepas de S. pyogenes causantes de enfermedad invasora y SSTE. Los aislamientos fueron recuperados de hemocultivos de pacientes internados en el Hospital Santamarina y en la Nueva Clínica Chacabuco (Tandil, Argentina) entre diciembre de 2000 y abril de 2005. Predominaron 2 patrones de electroforesis en campo pulsante. El más frecuente comprendió 5 aislamientos del tipo emm1-T1, con perfil de toxinas speA, speB, speF, speG y smeZ. El segundo patrón más frecuente incluyó 2 aislamientos tipo emm3-TNT (speB, speF, speG). Estos dos tipos (emm1 y emm3) fueron los prevalentes en las infecciones invasoras. Las otras tres cepas correspondieron a los tipos emm49-TNT (speB, speC, speF, speG), emm75-T25 (speB, speF, speG) y emm83-TNT (speB, speF, speG, ssa, smeZ). Se encontró diversidad genética entre las cepas aisladas, pero todos los aislamientos fueron sensibles a penicilina, cefotaxima, eritromicina, clindamicina, cloranfenicol, tetraciclina y rifampicina. Por tal motivo, aún es válido el tratamiento empírico con penicilina asociada a clindamicina.

We start by describing two of the main proposals for duality in abelian gauge theories, namely F(ield strength)-duality approach and the S-duality formalism. We then discuss how F-duality and S-duality can be applied to the case of linearized gravity. By emphasizing the similarities and differences between these two types of dualities we explore the possibility of combining them in just one duality formalism.

Comenzamos describiendo dos propuestas principales de dualidad en teorías abelianas de norma, a saber el enfoque de dualidad-(del campo)F y el formalismo de dualidad-S. De ahí, discutimos como la dualidad-F y la dualidad-S pueden implementarse para el caso de gravedad linealizada. Haciendo énfasis en las similitudes y diferencias entre estos dos tipos de dualidad, exploramos la posibilidad de combinarlos en un sólo formalismo de dualidad.

We develop a linearized five-dimensional Kaluza-Klein theory as a gauge theory. By perturbing the metric around flat and de Sitter backgrounds, we first discuss linearized gravity as a gauge theory in any dimension. In the particular case of five dimensions, we show that in using the Kaluza-Klein mechanism, the field equations of our approach imply both linearized gauge gravity and Maxwell theory in flat and de Sitter scenarios. As a possible further development of our formalism, we also discuss an application in the context of gravitational polarization scattering by means of the analogue of the Mueller matrix in optical polarization algebra. We argue that this application can be of particular interest in gravitational wave experiments.

Desarrollamos una teoría Kaluza-Klein linealizada en cinco dimensiones como una teoría de norma. Discutimos primero gravedad linealizada como una teoría de norma en cualquier dimensión perturbando las métricas de fondo plana y la de de Sitter. Demostramos que usando el mecanismo de Kaluza-Klein en el caso particular de cinco dimensiones, las ecuaciones de campo de nuestra aproximación implican tanto gravedad linealizada de norma como la teoría de Maxwell en escenarios planos y de de Sitter. Como otro posible desarrollo de nuestro formalismo, también discutimos una aplicación en el contexto de dispersión gravitacional polarizada, por medio de una matriz análoga a la de Mueller usada en el álgebra de polarización óptica. Argumentamos que esta aplicación puede ser de interés particular en los experimentos de ondas gravitacionales.

In this contribution, we review the derivation of the relativistic top geodesic deviation equation. This equation results in a generalization of the geodesic deviation equation for a pair of nearby point particles. This property is taken into account in investigating the detection of gravitational waves, and we show how our generalized formula for a relativistic top can be used to study the gravitational wave backgrounds. Besides of these facts, we argue that our formulation may be of special interest for detecting the inflationary gravitational waves via the polarization of the cosmic background radiation.

En esta contribución, revisamos la derivación de la ecuación de desviación de geodésicas para trompos relativistas. Esta ecuación es una generalización de la ecuación de geodésicas para un par de objetos puntuales cercanos. Esta propiedad es tomada en cuenta para investigar la detección de ondas gravitacionales, y mostramos cómo nuestra fórmula generalizada para un trompo relativista puede ser usada para estudiar los fondos de ondas gravitacionales. Además de estos hechos, argumentamos que nuestra formulación puede ser de especial interés para detectar las ondas gravitacionales inflacionarias a través de la polarización en la radiación cósmica de fondo.