Influência do risco de incumprimento nos retornos de capital

Sempre foi do interesse das instituições financeiras de crédito determinar o risco de incumprimento associado a uma empresa por forma a avaliar o seu perfil. No entanto, esta informação é útil a todos os stakeholders de uma empresa, já que também estes comprometem uma parte de si ao interagirem com esta. O aumento do número de insolvências nos últimos anos tem reafirmado a necessidade de ampliar e aprofundar a pesquisa sobre o stress financeiro. A identificação dos fatores que influenciam a determinação do preço dos ativos sempre foi do interesse de todos os stakeholders, por forma a antecipar a variação dos retornos e agir em sua conformidade. Nesta dissertação será estudada a influência do risco de incumprimento sobre os retornos de capital, usando como indicador do risco de incumprimento a probabilidade de incumprimento obtida segundo o modelo de opções de Merton (1974). Efetuou-se esta análise durante o período de Fevereiro de 2002 a Dezembro de 2011, utilizando dados de empresas Portuguesas, Espanholas e Gregas. Os resultados evidenciam uma relação negativa do risco de incumprimento com os retornos de capital, que é devida a um efeito momentum e à volatilidade. A par disso, também se demonstra que o tamanho e o book-to-market não são representativos do risco de incumprimento na amostra aqui utilizada, ao contrário do que Fama & French (1992; 1996) afirmavam.

Liderança, virtuosidade e criatividade explicando o desempenho de equipes

As organizações estão se tornando cada vez mais competitivas e buscando, constantemente, formas de aumentar o seu desempenho através da compreensão dos fatores que o antecedem. A nossa investigação incorpora dois estudos, ambos incidentes sobre as lojas de uma grande cadeia de varejo brasileira. O primeiro estudo, envolvendo 68 lojas, investiga como a liderança autêntica explica o desempenho das lojas através do efeito mediador da virtuosidade e da potência das equipes (uma espécie de sentido de eficácia coletiva). O segundo estudo, abrangendo 46 lojas, testa como a potência das equipes explica o respetivo desempenho através do efeito mediador da criatividade. Os principais resultados são: (a) a relação entre a liderança autêntica e o desempenho das lojas é totalmente mediada pela virtuosidade e pela potência das equipes; (b) a criatividade medeia a relação entre a potência das equipes e o desempenho das lojas; (c) a criatividade não explica diretamente o desempenho, mas parece influenciá-lo através do efeito mediador da potência. Os cuidados metodológicos destinados a diminuir os riscos de variância do método comum aumentam a validade dos estudos. Ao focar variáveis relacionadas com a virtuosidade, a liderança autêntica, e as forças das equipes, e ao incluir dados de desempenho objetivo, a nossa investigação é um contributo relevante para o movimento dos “Estudos Organizacionais Positivos”.

Mercaptans extraction from jet-fuel streams using ionic liquids

Desulfurization is one of the most important processes in the refining industry. Due to a growing concern about the risks to human health and environment, associated with the emissions of sulfur compounds, legislation has become more stringent, requiring a drastic reduction in the sulfur content of fuel to levels close to zero (< 10 ppm S). However, conventional desulfurization processes are inefficient and have high operating costs. This scenario stimulates the improvement of existing processes and the development of new and more efficient technologies. Aiming at overcoming these shortcomings, this work investigates an alternative desulfurization process using ionic liquids for the removal of mercaptans from "jet fuel" streams. The screening and selection of the most suitable ionic liquid were performed based on experimental and COSMO-RS predicted liquid-liquid equilibrium data. A model feed of 1-hexanethiol and n-dodecane was selected to represent a jet-fuel stream. High selectivities were determined, as a result of the low mutual solubility between the ionic liquid and the hydrocarbon matrix, proving the potential use of the ionic liquid, which prevents the loss of fuel for the solvent. The distribution ratios of mercaptans towards the ionic liquids were not as favorable, making the traditional liquid-liquid extraction processes not suitable for the removal of aliphatic S-compounds due to the high volume of extractant required. This work explores alternative methods and proposes the use of ionic liquids in a separation process assisted by membranes. In the process proposed the ionic liquid is used as extracting solvent of the sulfur species, in a hollow fiber membrane contactor, without co-extracting the other jet-fuel compound. In a second contactor, the ionic liquid is regenerated applying a sweep gas stripping, which allows for its reuse in a closed loop between the two membrane contactors. This integrated extraction/regeneration process of desulfurization produced a jet-fuel model with sulfur content lower than 2 ppm of S, as envisaged by legislation for the use of ultra-low sulfur jet-fuel. This result confirms the high potential for development of ultra-deep desulfurization application.

Derivation of soil screening values for metals in Portuguese natural soil

The increasing human activity has been responsible by profound changes and a constinuos degradation of the soil compartment in all the European territory. Some European policies are appearing focusing soil’s protection and the management of contaminated sites, in order to recover land for other uses. To regulate the risk assessment and the management of contaminated soils, many European member states adopted soil guideline values, as for example soil screnning values (SSV).These values are particularly useful for the the first tier of the Ecological Risk Assessment (ERA) processes of contaminated sites,especially for a first screening of sites requiring a more site-specific evaluation. Hence, the approriate definition of regional SSVs will have relevant economic impacts in the management of contaminated sites. Portugal is one of European Member States that still lack these soil guideline values. In this context, this study gaves a remarkable contribution in the generation of ecotoxicological data for soil microbiological parameters, terrestrial plants and invertebrates for the derivation of SSVs for uranium (U), cadmium (Cd) and copper (Cu), using a Portuguese natural soil, representative of a dominant type of soil in the Portuguese territory. SSVs were derived based on two methods proposed by the the Technical Guidance Document for Risk Assessment of the European Commission; namely the assessment factor method (AF) and the species sensitivity distribution (SSD) method (with some adaptations). The outputs of both methods were compared and discussed. Further, this study laid the foundation for a deeper reflection about the cut-off (hazard concentration for a given percentage of species - HCps) to be estimated from the SSDs, and to be selected for the derivation of SSVs, with the adequate level of protection. It was proven that this selection may vary for different contaminants, however a clear justification should be given, in each case. The SSvs proposed in this study were for: U (151.4 mg U kg-1dw), Cd (5.6 mg Cd kg-1dw), and Cu (58.5 mg Cu kg-1dw) These values should now be tested for their descriminating power of soils with different levels of contamination. However, this studies clarifies the approach that should be followed for the derivation of SSVs for other metals and organic contaminants, and for other dominant types of Portuguese natural soils.

Organic contaminants in urban soils: major inputs and potential risks

Urban soil quality may be severely affected by hydrophobic organic contaminants (HOCs), impairing environmental quality and human health. A comprehensive study was conducted in two contrasting Portuguese urban areas (Lisbon and Viseu) in order to assess the levels and potential risks of these contaminants, to identify sources and study their behaviour in soils. The concentrations of HOCs were related to the size of the city, with much higher contamination levels observed in Lisbon urban area. Source apportionment was performed by studying the HOCs profiles, their relationship with potentially toxic elements and general characteristics of soil using multivariate statistical methods. Lisbon seems to be affected by nearby sources (traffic, industry and incineration processes) whereas in Viseu the atmospheric transport may be playing an important role. In a first tier of risk assessment (RA) it was possible to identify polycyclic aromatic hydrocarbons (PAHs) in Lisbon soils as a potential hazard. The levels of PAHs in street dusts were further studied and allowed to clarify that traffic, tire and pavement debris can be an important source of PAHs to urban soils. Street dusts were also identified as being a potential concern regarding human and environmental health, especially if reaching the nearby aquatic bodies. Geostatistical tools were also used and their usefulness in a RA analysis and urban planning was discussed. In order to obtain a more realistic assessment of risks of HOCs to environment and human health it is important to evaluate their available fraction, which is also the most accessible for organisms. Therefore, a review of the processes involved on the availability of PAHs was performed and the outputs produced by the different chemical methods were evaluated. The suitability of chemical methods to predict bioavailability of PAHs in dissimilar naturally contaminated soils has not been demonstrated, being especially difficult for high molecular weight compounds. No clear relationship between chemical and biological availability was found in this work. Yet, in spite of the very high total concentrations found in some Lisbon soils, both the water soluble fraction and the body residues resulting from bioaccumulation assays were generally very low, which may be due to aging phenomena. It was observed that the percentage of soluble fraction of PAHs in soils was found to be different among compounds and mostly regulated by soil properties. Regarding bioaccumulation assays, although no significant relationship was found between soil properties and bioavailability, it was verified that biota-to-soil bioaccumulation factors were sample dependent rather than compound dependent. In conclusion, once the compounds of potential concern are targeted, then performing a chemical screening as a first tier can be a simple and effective approach to start a RA. However, reliable data is still required to improve the existing models for risk characterization.

Assessing the effectiveness of chemical treatment with nanomaterials in improving the quality of different industrial effluents

Industrial activities are the major sources of pollution in all environments. Depending on the type of industry, various levels of organic and inorganic pollutants are being continuously discharged into the environment. Although, several kinds of physical, chemical, biological or the combination of methods have been proposed and applied to minimize the impact of industrial effluents, few have proved to be totally effective in terms of removal rates of several contaminants, toxicity reduction or amelioration of physical and chemical properties. Hence, it is imperative to develop new and innovative methodologies for industrial wastewater treatment. In this context nanotechnology arises announcing the offer of new possibilities for the treatment of wastewaters mainly based on the enhanced physical and chemical proprieties of nanomaterials (NMs), which can remarkably increase their adsorption and oxidation potential. Although applications of NMs may bring benefits, their widespread use will also contribute for their introduction into the environment and concerns have been raised about the intentional use of these materials. Further, the same properties that make NMs so appealing can also be responsible for producing ecotoxicological effects. In a first stage, with the objective of selecting NMs for the treatment of organic and inorganic effluents we first assessed the potential toxicity of nanoparticles of nickel oxide (NiO) with two different sizes (100 and 10-20 nm), titanium dioxide (TiO2, < 25 nm) and iron oxide (Fe2O3, ≈ 85x425 nm). The ecotoxicological assessment was performed with a battery of assays using aquatic organisms from different trophic levels. Since TiO2 and Fe2O3 were the NMs that presented lower risks to the aquatic systems, they were selected for the second stage of this work. Thus, the two NMs pre-selected were tested for the treatment of olive mill wastewater (OMW). They were used as catalyst in photodegradation systems (TiO2/UV, Fe2O3/UV, TiO2/H2O2/UV and Fe2O3/H2O2/UV). The treatments with TiO2 or Fe2O3 combined with H2O2 were the most efficient in ameliorating some chemical properties of the effluent. Regarding the toxicity to V. fischeri the highest reduction was recorded for the H2O2/UV system, without NMs. Afterwards a sequential treatment using photocatalytic oxidation with NMs and degradation with white-rot fungi was applied to OMW. This new approach increased the reduction of chemical oxygen demand, phenolic content and ecotoxicity to V. fischeri. However, no reduction in color and aromatic compounds was achieved after 21 days of biological treatment. The photodegradation systems were also applied to treat the kraft pulp mill and mining effluents. For the organic effluent the combination NMs and H2O2 had the best performances in reduction the chemical parameters as well in terms of toxicity reduction. However, for the mine effluent the best (TiO2/UV and Fe2O3/UV) were only able to significantly remove three metals (Zn, Al and Cd). Nonetheless the treatments were able of reducing the toxicity of the effluent. As a final stage, the toxicity of solid wastes formed during wastewater treatment with NMs was assessed with Chironomus riparius larvae, a representative species of the sediment compartment. Certain solid wastes showed the potential to negatively affect C. riparius survival and growth, depending on the type of effluent treated. This work also brings new insights to the use of NMs for the treatment of industrial wastewaters. Although some potential applications have been announced, many evaluations have to be performed before the upscaling of the chemical treatments with NMs.

Avaliação ambiental estratégica de Planos Diretores Municipais

O objetivo do presente relatório de estágio é clarificar e sistematizar alguns conceitos associados à Avaliação Ambiental Estratégica (AAE) de Instrumentos de Gestão Territorial (IGT), e expor a aplicação desta ferramenta a um Plano Diretor Municipal (PDM). A Avaliação Ambiental Estratégica é um instrumento de avaliação da política de ambiente aplicado ao processo de planeamento para garantir que as considerações ambientais são integradas, a par das questões económicas e sociais, durante a fase de elaboração de planos e programas e antes da sua aprovação, com a finalidade de promover a adoção de soluções mais sustentáveis e o estabelecimento de diretrizes de seguimento que minimizem os impactes negativos. Em Portugal, a aplicação desta ferramenta de avaliação é um procedimento obrigatório desde a transposição da Diretiva 2001/42/CE, de 27 de junho para a ordem jurídica interna pelo Decreto-Lei n.º 232/2007, de 15 de junho. O processo de AAE desenvolve-se em três fases essenciais: o estabelecimento dos fatores críticos para a decisão, a avaliação e o seguimento. Este relatório de estágio analisa a aplicação da AAE à 1ª revisão do Plano Diretor Municipal de Castelo de Vide, onde se conclui que a identificação das oportunidades e riscos resultantes da estratégia de desenvolvimento territorial contribui para a prossecução do desenvolvimento sustentável e para uma tomada de decisão mais adequada.