On the renormalisability of gauge invariant extensions of the squared gauge potential

We show that gauge invariant extensions of the local functional \cO = \frac12\int d^4x A^2 have long range non localities which can only be ``renormalised'' with reference to a specific gauge. Consequently, there is no gauge independent way of claiming the perturbative renormalisability of these extensions. In particular, they are not renormalisable in the modern sense of Weinberg and Gomis. Critically, our study does not support the view that ghost fields play an indispensable role in the extension of a local operator into a non-local one as claimed recently in the literature.Comment: 1+13 pages. Revised version. New title and abstract. Extended introduction and several sentences have been inserted. Final version to appear in Physics Letters

Charge crossover at the U(1) Higgs phase transition

The type-I region of phase transitions at finite temperature of theU(1)-Higgs theory in 3+1 dimensions is investigated in detail using a Wilsonianrenormalisation group. We consider in particular the quantitative effectsinduced through the cross-over of the scale-dependent Abelian charge from theGaussian to a non-trivial Abelian fixed point. As a result, the strength of thefirst-order phase transition is weakened. Analytical solutions to approximateflow equations are obtained, and all characteristics of the phase transitionare discussed and compared to the results obtained from perturbation theory. Inaddition, we present a detailed quantitative study regarding the dependence ofthe physical observables on the coarse-graining scheme. This results inerror-bars for the regularisation scheme (RS) dependence. We find quantitativeevidence for an intimate link between the RS dependence and truncations of flowequations

Integrated study by NMR and X-ray Crystallography on the analysis of the molecular interactions in heme-binding proteins

Dissertação para obtenção do Grau de Doutor em Bioquímica, Especialidade Bioquímica EstruturalHeme is essential to all aerobic organisms, as it is involved in several biological processes. Due to its toxicity and high insolubility, several proteins transiently bind this molecule, ensuring the transport and insertion into heme proteins. A structural study of three heme-binding proteins, human SOUL protein and human and murine p22HBP is described in this dissertation. In chapter 1, an introduction to heme and its biological importance is performed and all the information related to the proteins previously mentioned is summarized. The basic principles of X-ray Crystallography and Nuclear Magnetic Resonance (NMR), the techniques used in the structural characterization of these proteins, are described. For the studies described in this thesis large amounts of pure protein are required. For this reason, hSOUL protein was cloned, and the overexpression and purification of hSOUL optimized – chapter 2. The overall structure of hSOUL is very similar to murine p22HBP solution structure. hSOUL protein structure determined by X-ray Crystallography is described in chapter 3 and the possible biological consequences are discussed. Understanding the heme interaction with hSOUL was an important objective of this work. For that, NMR, Fluorescence Quenching and Visible Spectroscopy studies were performed. The results obtained, and shown in chapter 4, indicate that the interaction, if it exists, is non-specific. The several experiments to crystallize human and murine p22HBP, in order to solve their three-dimensional structure in complex with heme and therefore understand heme-p22HBP interaction, are described in chapter 5. The main conclusions from the present work are drawn in chapter 6 together with the future perspectives.Fundação para a Ciência e a Tecnologia - (SFRH/BD/30239/2006 e PTDC/QUI/64203/200

O Internato Médico do HFF em 2019: Continuidade e novos desafios

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Evolução e coexistência do serviço de mensagens SMS em IMS

De modo a conquistar a confiança e potenciar a aceitação e adesão dos utilizadores às Redes de Próxima Geração (RPG), é necessário garantir que os serviços mais populares das redes legadas (GSM/GPRS) continuam presentes. O Short Message Service (SMS) é um serviço de “dados”, extremamente rentável para as operadoras de telecomunicações, que permite a troca de mensagens curtas entre utilizadores de redes móveis, fixas e indirectamente também com utilizadores da internet. Como se revela essencial expandir este serviço para a RPG ou permitir a sua interacção com os novos serviços de mensagens, foi efectuado um estudo onde é abordada a coexistência do SMS e do serviço de Instant Messaging (IM) nas redes legadas e nas novas redes all-IP. Neste estudo, identificam-se as normas relevantes, os protocolos utilizados e seu funcionamento nos serviços de mensagens da rede IP Multimedia Subsystem (IMS), e a forma como podem ser utilizados para garantir a interoperabilidade com o SMS. Neste artigo apresenta-se o resultado do estudo efectuado, com o objectivo de facilitar a compreensão da solução para interoperabilidade proposta pelas entidades normalizadoras, clarificando os conceitos relacionados e facilitando, desta forma, o desenvolvimento de soluções de interoperabilidade entre serviços nas redes legadas e de próxima geração. Neste contexto, são descritos os serviços de mensagens da rede IMS e os componentes responsáveis por permitir a interoperabilidade com o SMS, em particular o seu módulo IP Short Message Gateway (IP-SM-GW)

SMS over LTE : interoperability between legacy and next generation networks

To increase the trust and acceptance of Next Generation Networks (NGN) by new and existing subscribers, it is necessary to ensure that the most popular services of legacy networks (GSM/GPRS) are still in place. The Short Message Service (SMS) is a widespread data service with high revenue for telecommunication operators, which allows the exchange of short messages between fixed, mobile and, indirectly, Internet subscribers. In this context, it is essential to extend this service for the NGN and allow its interaction with the new messaging services. With that in mind, a study was carried out to ensure the coexistence between SMS and the Instant Messaging (IM) service present in NGN. The present study identifies the relevant technical specifications impacting on the functionality of the IP Multimedia Subsystem (IMS) messaging services so that the interoperability with SMS can be ensured. The results of this study, covered in this article, aim to help the comprehension of the proposed interoperability solution, and demonstrate that the exchange of messages between legacy and NGN messaging services or equipment can be successfully accomplished. In this context, both SMS and IMS messaging services are detailed, along with the main protocols they involve. Finally, the entity responsible for ensuring message interoperability - the IP Short Message Gateway (IP-SM-GW) - is presented and tested in a commercial delivery content testbed.(undefined

Gauge invariance and background field formalism in the exact renormalisation group

We discuss gauge symmetry and Ward-Takahashi identities for Wilsonian flows in pure Yang-Mills theories. The background field formalism is used for the construction of a gauge invariant effective action. The symmetries of the effective action under gauge transformations for both the gauge field and the auxiliary background field are separately evaluated. We examine how the symmetry properties of the full theory are restored in the limit where the cut-off is removed.Comment: version to be published in PL

The effectiveness of celebrity endorsement in aspiring new celebrities: Examining the effects of brand, congruence, charisma and overexposure

Purpose – Celebrity endorsement is a phenomenon widely used by companies and studied by researchers. Despite the generally positive aspects of endorsement on the evaluation of products, in some cases, celebrities cannot substantially help promote products. The purpose of this paper is to analyze the effectiveness of celebrity endorsement effect in an aspiring new celebrity. Design/methodology/approach – Four studies involving 664 respondents were conducted to analyze the effectiveness of the endorsement. In addition to verifying the existence of the effect (Study 1), studies were conducted focusing on contextual variables with the potential to modify effect. Study 2 analyzes the brand and charisma effects, Study 3 analyzes the congruence between celebrities and Study 4 analyzes the exposure level of the endorser celebrity. Findings – The results demonstrate the effectiveness of this celebrity endorsement, as well as the effect of different contexts on endorsement, demonstrating that although new celebrities are less affected by acclaimed celebrities, as they become better known, to use the endorsement of celebrities with charisma and who relating in some way to the aspiring celebrity, can be an effective strategy, especially for the beginners in the career. Originality/value – This research contributes to the knowledge of celebrity endorsement to fill the lack pointed out in previous studies in the field over the effectiveness of this effect and, above all, the moderator variables that can influence or even annul this effect. In addition, by developing its own image and reputation, the aspiring new celebrity receives less influence from the endorser