CFT in Conformally Flat Spacetimes

A new class of conformal field theories is presented, where the background gravitational field is conformally flat. Conformally flat (CF) spacetimes enjoy conformal properties quite similar to the ones of flat spacetime. The conformal isometry group is of maximal rank and the conformal Killing vectors in conformally flat coordinates are {\em exactly} the same as the ones of flat spacetime. In this work, a new concept of distance is introduced, the {\em conformal distance}, which transforms covariantly under all conformal isometries of the CF space. It is shown that precisely for CF spacetimes, an adequate power of the said conformal distance is a solution of the non-minimal d'Alembert equation.Comment: Minor changes and some clarifications added. Published version. 16 page

Weyl anomalies and the nature of the gravitational field

The presence of gravity generalizes the notion of scale invariance to Weyl invariance, namely, invariance under local rescalings of the metric. In this work, we have computed the Weyl anomaly for various classically scale or Weyl invariant theories, making particular emphasis on the differences that arise when gravity is taken as a dynamical fluctuation instead of as a non-dynamical background field. We find that the value of the anomaly for the Weyl invariant coupling of scalar fields to gravity is sensitive to the dynamical character of the gravitational field, even when computed in constant curvature backgrounds. We also discuss to what extent those effects are potentially observable.Comment: 37 pages, 1 tabl

Weighing the Vacuum Energy

We discuss the weight of vacuum energy in various contexts. First, we compute the vacuum energy for flat spacetimes of the form $\mathbb{T}^3 \times \mathbb{R}$, where $\mathbb{T}^3$ stands for a general 3-torus. We discover a quite simple relationship between energy at radius $R$ and energy at radius $\frac{l_s^2}{ R}$. Then we consider quantum gravity effects in the vacuum energy of a scalar field in $\mathbb{M}_3 \times S^1$ where $\mathbb{M}_3$ is a general curved spacetime, and the circle $S^1$ refers to a spacelike coordinate. We compute it for General Relativity and generic transverse {\em TDiff} theories. In the particular case of Unimodular Gravity vacuum energy does not gravitate.Comment: 32 pages. Minor correction

An overview on armor research for the laser fusion project HiPER

During the current preparatory phase of the European laser fusion project HiPER, an intensive effort has being placed to identify an armour material able to protect the internal walls of the chamber against the high thermal loads and high fluxes of x-rays and ions produced during the fusion explosions. This poster addresses the different threats and limitations of a poly-crystalline Tungsten armour. The analysis is carried out under the conditions of an experimental chamber hypothetically constructed to demonstrate laser fusion in a repetitive mode, subjected to a few thousand 48MJ shock ignition shots during its entire lifetime. If compared to the literature, an extrapolation of the thermomechanical and atomistic effects obtained from the simulations of the experimental chamber to the conditions of a Demo reactor (working 24/7 at hundreds of MW) or a future power plant (producing GW) suggests that “standard” tungsten will not be a suitable armour. Thus, new materials based on nano-structured W and C are being investigated as possible candidates. The research programme launched by the HiPER material team is introduced

SENTIMENT CASCADES IN THE 15M MOVEMENT Sentiment cascades in the 15M movement

Abstract Recent grassroots movements have suggested that online social networks might play a key role in their organization, as adherents have a fast, many-to-many, communication channel to help coordinate their mobilization. The structure and dynamics of the networks constructed from the digital traces of protesters have been analyzed to some extent recently. However, less effort has been devoted to the analysis of the semantic content of messages exchanged during the protest. Using the data obtained from a microblogging service during the brewing and active phases of the 15M movement in Spain, we perform the first large scale test of theories on collective emotions and social interaction in collective actions. Our findings show that activity and information cascades in the movement are larger in the presence of negative collective emotions and when users express themselves in terms related to social content. At the level of individual participants, our results show that their social integration in the movement, as measured through social network metrics, increases with their level of engagement and of expression of negativity. Our findings show that non-rational factors play a role in the formation and activity of social movements through online media, having important consequences for viral spreading

Preference of acromegaly patients for treatment attributes in Spain

Acromegaly; Growth hormone; Quality of lifeAcromegàlia; Hormona del creixement; Qualitat de vidaAcromegalia; Hormona del crecimiento; Calidad de vidaObjective Acromegaly is a rare disease caused by increased growth hormone secretion and a subsequent increase in insulin-like growth factor I (IGF-I) levels. Patients display multiple comorbidities that affect their quality of life (QoL). Treatment aims to maintain good biochemical control, tumour control and reduce the risk of comorbidities; however, their impact on QoL has been overlooked until recently. We interviewed patients to explore their preferences with regard to treatment attributes. Design A cross-sectional study based on interviews and a discrete choice experiment (DCE) in a Spanish cohort. Methods Adult patients diagnosed with acromegaly ≥1 year before the start of the study and under treatment were included. Treatment attributes were collected from patient testimony during face-to-face interviews. Then, a DCE was performed to elicit patient preferences for certain treatment attributes. Results Sixty-seven patients completed the study. QoL improvement was the most important treatment attribute (37%), followed by IGF-I control (20%), blood sugar control (17%) and tumour control (13%). Secondary attributes were pain associated with the route of administration (7%), diarrhoea (2%), administration method (2%) and storage conditions (2%). We then calculated the theoretical share of preference for existing treatments, based on the individual preference utility for each attribute and level. Pegvisomant obtained the highest share of preference overall, and the highest preference as a second-line treatment (53 and 95%, respectively). Conclusions QoL greatly influences patient treatment preference. Since acromegaly patients are informed and aware of their disease, treatment choices should always be shared with patients.This study was funded by Pfizer (Spain)