Spinning AdS Propagators

We develop the embedding formalism to describe symmetric traceless tensors in Anti-de Sitter space. We use this formalism to construct the bulk-to-bulk propagator of massive spin J fields and check that it has the expected short distance and massless limits. We also and a split representation for the bulk-to-bulk propagator, by writing it as an integral over the boundary of the product of two bulk-to-boundary propagators. We exemplify the use of this representation with the computation of the conformal partial wave decomposition of Witten diagrams. In particular, we determine the Mellin amplitude associated to AdS graviton exchange between minimally coupled scalars of general dimension, including the regular part of the amplitude.Comment: 48 pages, 6 figure

Organic Light Emitting Diodes: Photophysics of Thermally Activated Delayed Fluorescence Emitters and Device Characterization

In this thesis, the influence of bromine atoms on the mechanism responsible for the observation of thermally activated delayed fluorescence (TADF) is investigated. Heavy atoms, such as bromine, are well known to promote spin-orbit coupling (SOC), consequently facilitating the transition between singlet and triplet states by intersystem crossing (ISC). For that reason, organic heavy metal complexes are considered organic phosphors because their presence facilitates the radiative decay directly from the triplet state to the ground singlet state, giving origin to the observation of phosphorescence at room temperature. In TADF emitters triplet states are up-converted to high energy singlet excited state through thermally activated reverse intersystem crossing (RISC). Therefore, the presence of heavy atoms in the structure of TADF molecules poses an interesting question of knowing if whether it will assist RISC or if it will promote triplet decay directly to the ground state either through non-radiative processes or instead through phosphorescence. This work gives clear evidence that bromine causes direct triplet state radiative decay to the ground state, causing an otherwise strong TADF emitter to show significant phosphorescence, even at room temperature. A second objective of this thesis was to develop an experimental technique to directly probe the excited state dynamics and electroluminescence (EL) mechanism in working organic light emitting diodes (OLEDs), under device operation. This was accomplished by measuring the transient electroluminescence emission of TADF-based OLEDs on a newly assembled transient EL spectroscopy system developed within this project. These studies show that charge trapping plays an important role in the operation of OLEDs, and largely dominates the EL generation. This is a direct consequence of the intrinsically disordered nature of organic emitters

The role of leading twist operators in the Regge and Lorentzian OPE limits

We study two kinematical limits, the Regge limit and the Lorentzian OPE limit, of the four-point function of the stress-tensor multiplet in Super Yang-Mills at weak coupling. We explain how both kinematical limits are controlled by the leading twist operators. We use the known expression of the four-point function up to three loops, to extract the pomeron residue at next-to-leading order. Using this data and the known form of pomeron spin up to next-to-leading order, we predict the behaviour of the four-point function in the Regge limit at higher loops. Specifically, we determine the leading log behaviour at any loop order and the next-to-leading log at four loops. Finally, we check the consistency of our results with conformal Regge theory. This leads us to predict the behaviour around $J=1$ of the OPE coefficient of the spin $J$ leading twist operator in the OPE of two chiral primary operators.Comment: 22+14 page

Ventajas de la tintura por pulverización mediante la aplicación de pigmentos cromotrópicos.

Los pigmentos cromotrópicos o termocrómicos dan un buen resultado en la obtención de efectos especiales en el diseño textill si bien su elevado coste impide un uso más amplio. La aplicación mediante pulverización implica una significativa reducción de costes porque se necesita una cantidad inferior a la utilizada en los procesos de estampado tradicionales y también porque la no necesidad de preparar plantillas-tamiz hace que el tiempo requerido sea menor, adaptándose al propio tiempo, a las nuevas técnicas de gestión integrada en la cadena de abastecimiento, especialmente en lo que se refiere a respuesta rápida.Chromotropic or thermochromic pigments are a good way to obtain special effects in textile design, but its price is a impediment for a wider divulgation. The application by pulverization allo ws a significant reduction of costs because we need a smaller quantity than traditional printing processes, but also because as we don't need to prepare screens the time needed is reduced and is adapted to the new techniques of integrated management on the supplying chain of, namely the quick response.Les pigments chromotropiques ou thermotropiques donnent de bons résultats pour obtenir des effets spéciaux d'impression textile, mais leur coût élevé empeche de les utiliser plus sovent. L'application par pulvérisation implique une réduction significative des coûts. Il faut en effet des quantités moindres que les quantités utilisées avec des prix traditionnels d'impression et il n'est pas nécessaire de préparer des patrons-tamis, d'où un gain de temps et une meilleure adaptation aux nouvelles techniques de gestion intégrée dans la chaîne d'approvisionnement, notamment en ce qui concerne la réponse rapide.Peer Reviewe

Exploring the flexibility of scala implicits towards an extensible live environment

Tese de mestrado integrado. Engenharia Informática e Computação. Faculdade de Engenharia. Universidade do Porto. 201

The political uses of identity an enthnography of the northern league

This is a thesis about the Northern League (Lega Nord), a regionalist and nationalist party that rose to prominence during the last three decades in the north of Italy Throughout this period the Northern League developed from a peripheral and protest movement, into an important government force. In the last political elections (April 2008) the Northern League gained more than 20% of the votes in the North, guaranteeing in this a way an important role in the new conservative coalition guided by Silvio Berlusconi. In particular, I set out to explore the ways in which the Lega press for the construction of a northern national identity and offer this as a case study through which we might further our understanding of the social and political uses of identity in the context of modem Europe. The success of the Northern League has been largely explained, up until now, in terms of its capacity to represent, politically, the material conflicts between the industrialized but politically peripheral North and the central state. For this reason, the League's attempts to reconstruct a local ethnic identity and later on the creation and imagination of a northern nation (Padania) has been mainly analysed as a rational and pragmatic invention, used as part of the struggle for political power. Such an approach, however, can overlook the extent to which non-material circumstances (habits, beliefs, social practices, and moral ideas) influence individuals' political choices. Drawing on ethnographic fieldwork among Northern League activists in the region of Veneto, and more precisely in the provinces of Belluno and Treviso, these aspects were analysed in the following way. After establishing the historical and methodological context, I go on to consider the disaffection of the Northern League with the Italian state, its history and its institutions. I then investigate the Northern League's model of identity construction through the study of public ceremonies, political speeches, and ritual practices. I continue to draw on ethnographic fieldwork in order to make visible the relationship between the imagination of the Northern Identity and local social practices. I then go on to examine, at the micro level, a number of local economic practices and their connections with the League's ideology. The last chapter focuses on the role of gender, linking the self-representation of local men with the League’s concept of authority. I conclude that in order to understand the economy of identity, its production, exchange and circulation, identity has to be seen in the light of social actors' practices and direct experiences of everyday life. For this reason, I argue that leghismo ought to be understood not just as a subject of political representation, but also as a strategy through which local actors try to make sense of, and adapt to - or more importantly transform - their own social world