Phenomenology of Supersymmetric Theories with and without R-Parity

We review supersymmetry models with and without R-parity. After briefly describing the Minimal Supersymetric Standard Model and its particle content we move to models where R-parity is broken, either spontaneously or explicitly. In this last case we consider the situation where R-parity is broken via bilinear terms in the superpotential. The radiative breaking of these models is described in the context of $b$--$\tau$ and $b$--$\tau$--$t$ unification. Finally we review the phenomenology of these R-parity violating models.Comment: 9 pages, 5 Figures in Postscript. Talk given at the EuroConference on Frontiers in Particle Astrophysics and Cosmology, San Feliu de Guixols, Spain, 30 September - 5 October, 200

The effect of the sixth sulfur ligand in the catalytic mechanism of periplasmic nitrate reductase

The catalytic mechanism of nitrate reduction by periplasmic nitrate reductases has been investigated using theoretical and computational means. We have found that the nitrate molecule binds to the active site with the Mo ion in the +6 oxidation state. Electron transfer to the active site occurs only in the proton-electron transfer stage, where the MoV species plays an important role in catalysis. The presence of the sulfur atom in the molybdenum coordination sphere creates a pseudo-dithiolene ligand that protects it from any direct attack from the solvent. Upon the nitrate binding there is a conformational rearrangement of this ring that allows the direct contact of the nitrate with MoVI ion. This rearrangement is stabilized by the conserved methionines Met141 and Met308. The reduction of nitrate into nitrite occurs in the second step of the mechanism where the two dimethyl-dithiolene ligands have a key role in spreading the excess of negative charge near the Mo atom to make it available for the chemical reaction. The reaction involves the oxidation of the sulfur atoms and not of the molybdenum as previously suggested. The mechanism involves a molybdenum and sulfur-based redox chemistry instead of the currently accepted redox chemistry based only on the Mo ion. The second part of the mechanism involves two protonation steps that are promoted by the presence of MoV species. MoVI intermediates might also be present in this stage depending on the availability of protons and electrons. Once the water molecule is generated only the MoVI species allow water molecule dissociation, and, the concomitant enzymatic turnover.Fil: Cerqueira, N.M.F.S.A.. Faculdade de Ciências E Tecnologia, Universidade Nova de Lisboa; PortugalFil: Gonzalez, P.J.. Faculdade de Ciências E Tecnologia, Universidade Nova de Lisboa; PortugalFil: Brondino, Carlos Dante. Universidad Nacional del Litoral; ArgentinaFil: Romão, M.J.. Faculdade de Ciências E Tecnologia, Universidade Nova de Lisboa; PortugalFil: Romão, C.C.. Instituto de Tecnologia Qu&Fil: Moura, I.. Faculdade de Ciências E Tecnologia, Universidade Nova de Lisboa; PortugalFil: Moura, J.J.G.. Faculdade de Ciências E Tecnologia, Universidade Nova de Lisboa; Portuga

Benefits management for an e-invoice process

This paper presents the application of a Benefits Management (BM) Methodology to an e-lnvoice project, and analyzes the results brought forth by the application of the methodology to the project and its contribution towards a wider adoption in the targeted Organization. A Case Study research method has been used which began with a gathering and treatment of data related to the emission and reception of the invoices, continued with the identification of the type of investment and ended with the application of the chosen BM approach. The methodology demonstrated the financial viability of the project, identified and structured the resulting benefits and facilitated the understanding and preparation for the required transformations in the Organization, including processes, competencies/skills and technologies. The BM approach brings to the Organization a more wide and consolidated vision for the projects, a greater foresight and support for a rational decision on IS/IT investments and the strategic alignment of resources with the company objectives and priorities

Determinantes da rentabilidade do sector turístico em Portugal

A presente dissertação pretende estudar o efeito na rentabilidade das empresas do setor turístico, de um conjunto de indicadores internos (de financiamento e de crescimento) e condicionantes externas das empresas, para as pequenas e médias empresas de Portugal entre 2009 e 2017. Para tal são usados modelos de estimação com dados de painel envolvendo um conjunto de 2508 empresas. A rentabilidade foi formulada através dos índices de rentabilidade sobre o investimento, a rentabilidade dos capitais próprios e a rentabilidade sobre os ativos. Dos resultados obtidos conclui-se que os indicadores internos de dimensão e idade das empresas, as condicionantes externas do crescimento do PIB, crise de dívida soberana e a localização das empresas, possuem um impacto estatisticamente significativo na sua rentabilidade. Conclui-se que as empresas de turismo devem ter um forte foco e precisão nos fatores positivos para melhorar seu desempenho; Determinants of the profitability of the tourism sector in Portugal Abstract: This dissertation studies the effect on corporate profitability, of a set of internal indicators (of financing and growth) and external constraints, for small and medium-sized companies in Portugal between 2009 and 2017 in the tourism sector. For this purpose, estimation models with panel data involving a group of 2508 companies have been used. Profitability was formulated through the return-on-investment indexes, the return on equity and the return on assets. From results obtained, it is concluded that the internal indicators, size and age of the companies, the external constraints of GDP growth, sovereign debt crisis and the location of the companies, have a statistically significant impact on their profitability. It is concluded that tourism companies must have a strong focus and precision on positive factors to improve their performance

A fase de deformação sarda na Zona Centro-Ibérica

Ao longo da Zona Centro-Ibérica a transição entre as sequências de idade Câmbrica e as sequências ordovícicas sobrejacentes evidencia sempre a actuação da fase Sarda s.l. No entanto, a forma como se manifesta esta deformação de idade pré- Quartzito Armoricano é bastante heterogénea: na generalidade dos casos apenas se evidencia através de um nível erosivo significativo que marca uma disconformidade, enquanto noutros corresponde a uma discordância de alto ângulo, onde por vezes chega a ocorrer inversão da polaridade. Estas relações que são encontradas em toda a Zona Centro-Ibérica sugerem que a fase Sarda s.l. terá correspondido a um episódio de inversão transiente no processo extensivo que afectou o bordo da Gondwana durante grande parte do Paleozóico inferior

R--Parity Violating Signals for Chargino Production at LEP II

We study chargino pair production at LEP II in supersymmetric models with spontaneously broken R-parity. We perform signal and background analyses, showing that a large region of the parameter space of these models can be probed through chargino searches at LEP II. In particular, we determine the attainable limits on the chargino mass as a function of the magnitude of the effective bilinear R-parity violation parameter $\epsilon$, demonstrating that LEP II is able to unravel the existence of charginos with masses almost up to its kinematical limit even in the case of R-parity violation. This requires the study of several final state topologies since the usual MSSM chargino signature is recovered as $\epsilon \to 0$. Moreover, for sufficiently large $\epsilon$ values, for which the chargino decay mode $\chi^\pm \to \tau^\pm J$ dominates, we find through a dedicated Monte Carlo analysis that the $\chi^\pm$ mass bounds are again very close to the kinematic limit. Our results establish the robustness of the chargino mass limit, in the sense that it is basically model-independent. They also show that LEP II can establish the existence of spontaneous R-parity violation in a large region of parameter space should charginos be produced.Comment: improved analyses; 31 pages and 9 figures (included

The Ibero-Armorican arc: indentation versus self-subduction

In the Iberian Variscides it is possible to distinguish major arcuate structures; although highly studied, their characterization and genesis are still a matter of controversy. The main Ibero- Armorican Arc (IAA) is essentially defined by a NW–SE trend in the Iberian branch and an E–W trend in the Brittany branch; however, in northern Spain it is rotated 180º, sometimes known as the Cantabrian Arc (CA). The relationship between these arcs is debatable, being considered either as a single arc generated in one tectonic event, or the result of polyphase bending process. According to the last assumption, there is a later arcuate structure (CA), overlapping a previous major one (IAA). Whatever the proposed models, they must explain the presence of a sinistral transpression regime in Iberia and a dextral one in Armorican branch, and the temporal deformation range of Devonian to Upper Carboniferous (Dias and Ribeiro, 1995)

Arco Ibero-Armoricano: indentação versus auto-subducção

No Varisco da Ibéria têm sido identificadas diversas macroestruturas arqueadas cuja caracterização e génese é objecto de controvérsia. Neste trabalho discutem-se os argumentos associados a cada uma destas estruturas, bem como os processos de formação dos arcos Ibero-Armoricano e Cantábrico. Os elementos existentes sugerem uma génese polifásica, onde a indentação de um promontório principal da Gondwana aparece como um elemento fundamental

A Review of the Arcuate Structures in the Iberian Variscides; Constraints and Genetical Models

In the Iberian Variscides several first order arcuate structures have been considered. In spite of being highly studied their characterization, formation mechanisms and even existence is still debatable. Themain Ibero-Armorican Arc (IAA) is essentially defined by a predominantNW–SE trend in the Iberian branch and an E–Wtrend in the Brittany one. However, in northern Spain it presents a 180° rotation, sometimes known as the Cantabrian Arc (CA). The relation between both arcs is controversial, being considered either as a single arc due to one tectonic event, or as the result of a polyphasic process. According to the last assumption, there is a later arcuate structure (CA), overlapping a previousmajor one (IAA). Whatever themodels, they must be able to explain the presence of a Variscan sinistral transpression in Iberia and a dextral one in Armorica, and a deformation spanning from the Devonian to the Upper Carboniferous. Another arcuate structure, in continuity with the CA, the Central-Iberian Arc (CIA) was recently proposed mainly based upon on magnetic anomalies, geometry of major folds and Ordovician paleocurrents. The critical review of the structural, stratigraphic and geophysical data supports both the IAA and the CA, but as independent structures. However, the presence of a CIA is highly questionable and could not be supported. The complex strain pattern of the IAA and the CA could be explained by a Devonian — Carboniferous polyphasic indentation of a Gondwana promontory. In thismodel the CA is essentially a thin-skinned arc,while the IAA has a more complex and longer evolution that has led to a thick-skinned first order structure. Nevertheless, both arcs are essentially the result of a lithospheric bending process during the Iberian Variscides

O Processo de Implementação das Ações Afirmativas na Universidade de Brasília(1999-2004)

The article intends to analyze the process that leads the University of Brasilia (UnB) to approve the implementation of the system of quotas for black and indigenous students in June of 2003. The intention is put the process under historical perspective, detaching the paper and the meaning of each agent involved in it. Moreover, the article searches to dialogue critically with the bibliography that analyzes the case of the UnB.O artigo pretende analisar o processo que levou a Universidade de Brasília (UnB) a aprovar a implementação do sistema de cotas para estudantes negros e indígenas em junho de 2003. A intenção é colocar o processo em perspectiva histórica, destacando o papel o e significado de cada um dos vários agentes envolvidos. Além disso, busca-se dialogar criticamente com a bibliografia que analisa o caso da UnB