Image Normalization of Wiener-Hopf operators and boundary-transmission value problems for a junction of two half-planes

The present paper deals with an application of the image normalization technique for certain classes of Wiener-Hopf operators (WHOs) associated to ill-posed boundary-transmission value problems. We briefly describe the method of normalization and then apply it to boundary-transmission value problems issued from diffraction problems for a junction of two half-planes, which are relevant in mathematical physics applications. We consider different boundary-transmission conditions on the junction of the two semi-infinite half-planes and analyze the not normally solvability of the corresponding operators.Comment: 15 page

Emu, Exchange Rate Volatility and Bid-Ask Spreads

This study deals with two issues related to the determination of exchange rate bid-ask spreads in the transition to EMU. First, we discuss how a credible announcement of conversion rates affects exchange rate volatility in the run up to the introduction of the Euro. Second, we discuss the theoretical relation that exists between exchange rate uncertainty and the bid-ask spread. The theory suggests that there is a positive association between exchange rate uncertainty and transaction costs and that we should observe a gradual reduction of exchange rate volatility in the transition to EMU. This theory implies a gradual shrinking of the bid-ask spread during the transition period. These conjectures are subject to empirical testing in the case of the exchange rate of the Portuguese escudo against the Deutsche Mark.

Laser-light scattering approach to peptide–membrane interaction

© International University Line, 2010Membrane-active peptides are becoming widely used, mainly due to their high therapeutic potential. Although the therapeutic action is characterized, the mechanisms of interaction are often unclear or controversial. In biophysical studies, non-invasive techniques are overlooked when studying the effect of peptides on membranes. Light scattering techniques, such as dynamic light scattering and static light scattering, can be used as tools to determine whether promotion of membrane aggregation in the presence of peptides and of self-peptide aggregation in solution occurs. More recently, light scattering has been used for evaluating the alteration on membrane surface charge (ζ-potential) promoted by membrane–peptide interactions. The data obtained by these techniques (either by themselves or combined with complementary experimental approaches) therefore yield valuable elucidations of membrane-active peptides’ mechanisms of action at the molecular level.This work was partially supported by the Fundação para a Ciência e Tecnologia (FCT) of the Portuguese Ministry of Science, Technology and Higher Education. M.M.D. acknowledges the grant SFRH/BD/41750/2007 from FCT

Stationary scalar and vector clouds around Kerr-Newman black holes

Massive bosons in the vicinity of Kerr-Newman black holes can form pure bound states when their phase angular velocity fulills the synchronisation condition, i.e. at the threshold of superradiance. The presence of these stationary clouds at the linear level is intimately linked to the existence of Kerr black holes with synchronised hair at the non-linear level. These configurations are very similar to the atomic orbitals of the electron in a hydrogen atom. They can be labeled by four quantum numbers: $n$, the number of nodes in the radial direction; $\ell$, the orbital angular momentum; $j$, the total angular momentum; and $m_j$, the azimuthal total angular momentum. These synchronised configurations are solely allowed for particular values of the black hole's mass, angular momentum and electric charge. Such quantization results in an existence surface in the three-dimensional parameter space of Kerr-Newman black holes. The phenomenology of stationary scalar clouds has been widely addressed over the last years. However, there is a gap in the literature concerning their vector cousins. Following the separability of the Proca equation in Kerr(-Newman) spacetime, this work explores and compares scalar and vector stationary clouds around Kerr and Kerr-Newman black holes, extending previous research.Comment: 17 pages, 6 figures. Contribution to Selected Papers of the Fifth Amazonian Symposium on Physics (accepted in IJMPD

Seminário Permanente de Psicologia Organizacional e Recursos Humanos - 18ª edição

Questionário de Reconhecimento da Singularidade Contributiva: estudos psicométricos Será apresentado o processo de construção do Questionário de Reconhecimento da Singularidade Contributiva, os estudos psicométricos e os estudos diferenciais realizados com o instrumento. Serão apresentadas reflexões sobre as implicações do conceito e apresentadas sugestões de estudos futuros

A "diamond-ring" star: the unusual morphologic structure of a young (multiple?) object

We have observed IRAS06468-0325 obtaining optical and infrared images through IJHKs and L' filters, K-band low-resolution spectroscopy, together with millimetre line observations of CO and CS. IRAS06468-0325 has a very unusual and enigmatic morphology with two components: a bright, close to point-like source (the diamond) and a sharp-edge ring-like structure (the ring). The source is not detected in the optical, at wavelengths shorter than the I-band. The diamond is seen in all the imaging bands observed. The ring-like structure in IRAS06468-0325 is clearly seen in the I, J, H, and Ks. It is not detected in the L'-band image. Infrared colours of the diamond are compatible with excess circumstellar emission and a young stellar nature. A strongly non-gaussian and moderately bright CO(1-0) and {13}CO(2-1) lines are seen towards IRAS06468-0325, at v_{LSR} of 30.5 km s{-1} (corresponding to a kinematic distance of 3 kpc). Very weak C{18}O(2-1) and CS(2-1) lines were detected. K-band spectra of the diamond and of the ring are similar both in the slope of the continuum and in the presence of lines supporting the idea that the ring is reflected light from the diamond. With the current data, a few different scenarios are possible to explain the morphology of this object. However, the available data seem to favour that the morphology of IRAS06468-0325 correspond to a young stellar multiple system in a transient stage where a binary co-exists with a circumbinary disc, similar to the case of GG Tau. In this case, the sharpness of the well-defined ring may be due to tidal truncation from dynamic interactions between components in a binary or multiple stellar system. IRAS06468-0325 may be an important rare case that illustrates a short-lived stage of the process of binary or multiple star formation.Comment: 7 pages, 6 figure

Obres per al violí en un llibre d'orgue del segle XVII: el manuscrit 387 de la Biblioteca de Catalunya

El present treball dóna a conèixer un conjunt d'obres de cambra, per a violí, integrades en un manuscrit per a orgue copiat entre els anys 1694 i 1697. Entre les gairebé cinc-centes composicions per a orgue que conté, la majoria compostes per Joan Cabanilles (1644-1712), es troba un conjunt de set composicions instrumentals a dues i tres veus, del compositor romà Francesco Foggia (1604-1688). Pel gran interès que aquestes obres tenen, es dóna aquí notícia d'elles, amb una breu descripció de la font i del material objecte d'estudi, així com la transcripció crítica de la primera obra del conjunt (la Tocata ytaliana para violín y violón), a manera d'avanç, abans d'editar l'estudi complet i edició crítica detallada de tot el fons documental d'aquestes obres, actualment en curs.This work presents a set of chamber pieces for the violin contained in a manuscript for the organ copied between 1694 and 1697. Among the almost 500 compositions for the organ contained therein, most composed by Joan Cabanilles (*1644; †1712), is a set of seven instrumental compositions for two and three voices by the Roman composer Francesco Foggia (*1604; †1688). Because of the great interest these works represent, information is provided on them including a brief description of the source and the material under study, as well as a critical transcription of the first piece in the set (the Tocata ytaliana para violín y violón). This is a preliminary publication before the complete study and a detailed critical edition are published of all the documents related to these pieces, currently being produced

Qualidade de vida, competitividade e disfunções coletivas

É apresentado o conceito de qualidade de vida e enquadrado no contexto atual. A competitividade é realçada no seu paradoxo: como fator de desenvolvimento (e contributiva para a qualidade de vida) e como fator de clivagem e disfunção social. É proposto que a ideologia da competição, associada ao desenvolvimento tecnológico galopante seja fraturante e desencadeadora de conflitualidade social que compromete a qualidade de vida. É sugerida uma superação das limitações do conceito de competitividade com o conceito de contributividade, que é mais inclusivo e realizante. Esta abordagem é reforçada pelo contraponto ao conceito de contrato social: o conceito de laço social, na base estruturante de qualquer sociedade. É analisado o papel das interfaces entre saberes, entre especialidades, entre organizações, entre competências nucleares para a construção de soluções integradas e mais realizantes, mais capazes de conjugar a qualidade de vida com o desenvolvimento