Statistical analysis of entropy correction from topological defects in Loop Black Holes

In this paper we discuss the entropy of quantum black holes in the LQG formalism when the number of punctures on the horizon is treated as a quantum hair, that is we compute the black hole entropy in the grand canonical (area) ensemble. The entropy is a function of both the average area and the average number of punctures and bears little resemblance to the Bekenstein-Hawking entropy. In the thermodynamic limit, both the "temperature" and the chemical potential can be shown to be functions only of the average area per puncture. At a fixed temperature, the average number of punctures becomes proportional to the average area and we recover the Bekenstein-Hawking area-entropy law to leading order provided that the Barbero-Immirzi parameter, $\gamma$, is appropriately fixed. This also relates the chemical potential to $\gamma$. We obtain a sub-leading correction, which differs in signature from that obtained in the microcanonical and canonical ensembles in its sign but agrees with earlier results in the grand canonical ensemble.Comment: 12 pages, no figures. Version to appear in Phys. Rev.

New tools for Loop Quantum Gravity with applications to a simple model

Loop Quantum Gravity is now a well established approach to quantum gravity. One of the main challenges still faced by the theory is constructing a consistent dynamics which would lead back to the standard dynamics of the gravitational field at large scales. Here we will review the recent U(N) framework for Loop Quantum Gravity and the new spinor representation (that provides a classical setting for the U(N) framework). Then, we will apply these techniques to a simple model in order to propose a dynamics for a symmetry reduced sector of the theory. Furthermore, we will explore certain analogies of this model with Loop Quantum Cosmology.Comment: 4 pages, to appear in Proceedings of Spanish Relativity Meeting 2011 (ERE 2011) held in Madrid, Spai

Dynamics for a 2-vertex Quantum Gravity Model

We use the recently introduced U(N) framework for loop quantum gravity to study the dynamics of spin network states on the simplest class of graphs: two vertices linked with an arbitrary number N of edges. Such graphs represent two regions, in and out, separated by a boundary surface. We study the algebraic structure of the Hilbert space of spin networks from the U(N) perspective. In particular, we describe the algebra of operators acting on that space and discuss their relation to the standard holonomy operator of loop quantum gravity. Furthermore, we show that it is possible to make the restriction to the isotropic/homogeneous sector of the model by imposing the invariance under a global U(N) symmetry. We then propose a U(N) invariant Hamiltonian operator and study the induced dynamics. Finally, we explore the analogies between this model and loop quantum cosmology and sketch some possible generalizations of it.Comment: 28 pages, v2: typos correcte

A bonding evolution theory study on the catalytic Noyori hydrogenation reaction

The electronic rearrangements involved in Noyori hydrogenation reactions with double bonds (ethene and formaldehyde) are analysed using the bonding evolution theory. The study and analysis of the changes on the electron localisation function topology along a given reaction path reveals fluxes of electron density, allowing to unambiguously identify the main chemical events happening along the chemical reactions. This analysis shows that the first hydrogen transfer (with hydride character) occurs before the transition state (TS), while the second hydrogen transfer (with proton character) takes places after having reached the TS. The lower energy barrier found for formaldehyde over ethene is explained by two reasons. First, the hydride transfer is favoured for the C = O bond over C = C due to the electrophilic character of the carbon atom. Second, a negatively charged CH3–X (X = CH2, O) hidden intermediate is formed in the proximities of the TS region. The oxygen atom is able to stabilise this negatively charged species more effectively than the CH2 group due to its higher electronegativity and the presence of V(O) lone pairs. The obtained analysis explains and rationalises catalyst chemoselectivity (C = O vs. C = C). Finally, a curly arrow representation diagram accounting for the electronic rearrangements is proposed on the basis of BET results

Análisis químico de muestras minoritarias por procedimientos no destructivos, FRX, de útiles metálicos de la edad del bronce del sureste español

En el presente trabajo se expone las earaeterísticas prineipales de un nuevo sistema de toma de muestras y su portamuestras. eon objeto de emplearlo en el análisis químici^ de muestras arqueológieas. empleando 0.2 g eomo máximo, con lo que se conserva la integridad del objeto analizado. En este caso se utiliza un espectrómetro .seeuencial Philips PW1400. de tluorcseencia de rayos X. El ci tado mcttKlo et>nsigue altas cotas de Habilidad y exactitud en los elementos quí micos elegidos para su análisis

Antecedents and consequences of stress in retailing: environmental expectations and promoter scoring

Purpose: The aim of this paper is to examine the effects of the disconfirmation of expectations of crowding and mall accessibility, on stress and two marketing outcomes, satisfaction and promoter scoring. Design/methodology/approach: Data were obtained through two face-to-face surveys from mall shoppers that answered them at two different moments of their shopping experience, before entering the mall and before leaving it. Results are obtained from 230 customers that answered the two questionnaires. Findings: The findings suggest that stress indirectly influences customer promoter scoring through satisfaction, while disconfirmation of expectations influences it directly and indirectly. Practical implications: These results also suggest that stress and disconfirmation of expectations about crowding and accessibility are important in determining promoter scoring. To reduce stress and increase satisfaction and promoter scoring, managers should focus on exceeding customers'' expectations about mall accessibility and on ensuring that customers experience a lower level of crowding than they expected. Originality/value: The article examines Net Promoter Scoring, an outcome that has attracted managers'' attention but little is known about its antecedents. The paper provides evidence of the effect of disconfirmation of expectations and negative emotions on promoter scoring

Atmospheric excitement, customers’ moods and gender: A study of young shoppers

This paper aims to demonstrate how both incidental moods and gender can moderate the relationship between the level of excitement triggered by a mall environment and shopping behaviour. Our method is based on a 4 × 2 between subjects experiment with a final sample of 377 Spanish undergraduates. The study analyses four incidental moods that differ in the dimensions of valence and arousal, and their interaction effects with two atmospheric scenarios in a mall (exciting versus non-exciting atmospheres). Our findings support mood regulation theory for positive low-arousal individuals, and reject this theory for the rest of mood conditions. Additionally, arousal reduces customers’ cognitive capabilities, confirming previous research. This means that high-arousal shoppers are not influenced by a mall environment. Finally, gender differences are only found within more frequent shoppers and for negative low-arousal (NLA) shoppers. Managerial implications are provided regarding the creation of relaxing areas or the stimulation of shoppers