Browsing by Issue Date, starting with "2008-11"
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- High speed rail transport valuationPublication . Pimentel, Pedro; Azevedo-Pereira, José; Couto, GualterThe present paper investigates the optimal timing of investment for a high speed rail (HSR) project, in an uncertain environment, using a real options analysis (ROA) framework. It develops a continuous time framework with stochastic demand that allows for the determination of the optimal timing of investment and the value of the option to defer in the overall valuation of the project. The modelling approach used is based on the differential utility provided to railway users by the HSR service.
- High speed rail transport valuation and policy decisionsPublication . Pimentel, Pedro; Azevedo-Pereira, José; Couto, GualterThe present paper investigates the process of decision making regarding the optimal timing to invest in the high speed rail (HSR) project, under uncertainty, using the real options analysis (ROA) framework. It’s developed a continuous time framework that allows a solution to the problem concerning the optimal timing to invest and to value the impact of the option to defer in the overall valuation of the project, with multiple uncertainty factors. Besides considering a stochastic demand, the effect of uncertainty in the investment’s expenditure and over the benefit per user is incorporated in a model with three stochastic variables. The modelling approach used is based on the differential utility provided to railway users by the HSR service.
- Essential and non-essential trace metals in scalp hair of men chronically exposed to volcanogenic metals in the Azores, PortugalPublication . Amaral, André; Arruda, Mónica; Cabral, Susana; Rodrigues, ArmindoVolcanoes produce and release large amounts of toxicants, and the concentration of metals in hair can be used as a biomarker of exposure to trace metals. In order to investigate whether humans exposed to volcanic emissions demonstrate higher concentrations of essential and non-essential trace metals, scalp hair of men (3–89 years) living in two areas of the Azores, one exposed to volcanic emissions and the other not, was sampled, and their content in Cd, Cu, Pb, Rb, Se, and Zn was quantified by using High Resolution Inductively Coupled Plasma Mass Spectrometry. In average, men exposed to volcanic emissions presented higher concentrations of Cd (96.9 ppb), Cu (16.2 ppm), Pb (3417.6 ppb), Rb (216.3 ppb), and Zn (242.8 ppm), but not Se (469.6 ppb). Also, strong and significant correlations were found between Cd–Rb and Pb–Rb in the exposed men. In conclusion, humans living chronically exposed to volcanic emissions show high concentrations of essential and non-essential trace metals in scalp hair, and is suggested that this type of exposure may be as harmful as living close to industrial facilities.
- Expected time to invest in a new locationPublication . Couto, Gualter; Nunes, Cláudia; Silva, BrunoIn this paper we study the expected time to invest in a new location. In particular we derive expected values of the optimal timing regarding the decision of relocation of a company. We address two classes of scenarios. In the first one we assume that new (and potentially more efficient) spots become available according to a non-homogeneous Poisson process, whereas in the second we assume a conditional Poisson process. For both scenarios we derive mathematical expressions for the expected value of the firm in specific situations, where the intensity function is some particular function. We end up the paper presenting numerical illustrations of the derived results.
- Influência das fontes hidrotermais marinhas de baixa profundidade na composição das comunidades de meiofaunaPublication . Mendes, Ana Rita MarquesEste trabalho tem como objectivo o conhecimento da influência das fontes hidrotermais de baixa profundidade na composição da meiofauna. A recolha de sedimento foi efectuada a uma profundidade máxima de 7 metros, por mergulho com escafandro autónomo na zona em estudo (Ribeira Quente) e numa zona de controlo (Caloura). Em laboratório crivou-se e preparou-se o material recolhido para microscopia. Contaram-se e identificaram-se, em grandes grupos, os organismos com base em bibliografia especializada. Foram identificados 16 taxa no total da amostragem. Os grupos dominantes na Ribeira Quente foram o estado larvar Nauplii, os taxa Harpacticoida e Foraminifera e na Caloura os taxa Foraminifera, Ostracoda e Gastropoda. A Ribeira Quente demonstrou uma maior diversidade e uma menor abundância de organismos que a Caloura. Foram efectuados testes estatísticos para determinar a similaridade dos locais de amostragem, no entanto, esta hipótese foi rejeitada. A composição e distribuição da meiofauna pode ser influenciada pelas fontes hidrotermais de baixa profundidade, no entanto, é necessário determinar a extensão desta influência e considerar a realização de mais estudos sobre a composição e densidade da meiofauna nos Açores.
- Painho-de-Monteiro : uma nova espécie de uma velha avePublication . Neves, Verónica C.[…]. O nome científico do Paínho-da-Madeira é “Oceanodroma castro” e o nome científico da nova espécie agora descrita é “Oceanodroma monteiroi” ou Paínho-de Montteiro. As designações vernacular – “de Monteiro” – e científica – “monteiroi” – perpetuarão assim a memória do investigador Luís Rocha Monteiro que tanto contribuiu para a descoberta e conservação desta espécie. […].
- Prospecção de recursos minerais nos Açores : modelo integrador de valores ambientais e de ordenamento do territórioPublication . Caetano, Sérgio Diogo Santos; Nunes, João CarlosO aproveitamento dos recursos naturais é uma estruturante actividade do Ordenamento do Território. Quando se tratam, como é o caso dos recursos minerais, de recursos inamovíveis, não renováveis à escala humana e que ocorrem em condições geológicas específicas, o seu aproveitamento é fortemente condicionado pelas suas características de ocorrência e distribuição territorial. No Arquipélago dos Açores o aproveitamento de recursos minerais assume uma relevância fundamental ao nível do planeamento regional, quando se pretendem definir estratégias sustentáveis de aproveitamento dos recursos geológicos, sobretudo pelo facto das ilhas constituírem sistemas isolados, com acentuada descontinuidade e exiguidade territorial. A presente tese de mestrado incide no estudo da actual situação de referência da exploração de recursos minerais terrestres nos Açores e respectiva integração no sistema de gestão territorial vigente, visando estabelecer propostas que possam contribuir para a beneficiação de políticas de planeamento territorial futuras.
- Bioavailability of heavy metals and their effects on the midgut cells of a phytopaghous insect inhabiting volcanic environmentsPublication . Rodrigues, Armindo; Cunha, Luís; Amaral, André; Medeiros, Jorge; Garcia, PatríciaOrganisms living in volcanic environments are chronically exposed to metals, either as particles or associated with gases, from volcanic emissions, being therefore potential sentinels of the effects derived from such exposure. Concentrations of Ca, Cd, Cu, Mg, Mn, Pb, Rb, and Zn were measured in soil, grass (Lolium perenne), and larvae of Pseudaletia uninpuncta captured in sites exposed and non-exposed to volcanic activity. The midgut epithelial cell morphometry and apoptosis of P. unipuncta larvae were also analyzed. Larvae from the site with volcanic activity showed higher levels of Cu, Mn, Rb and Zn. Metals such as Pb, Cd and Mg levels of P. unipuncta larvae were similar between sites. Apoptosis was higher in cells from digestive epithelium of larvae exposed to volcanic activity. Soils and grass not exposed to volcanic activity showed higher levels for most of the analyzed elements with the exception of Rb. Such result when compared with metal levels of larvae may reveal that bioavailability of elements differs between sites. The higher levels of Cd, Zn and Mg in soils and grass from the site with no volcanic activity are probably related to the severe artificial fertilization in the studied pastures. Such result, when compared with metal levels of larvae, suggest that the bioavailability of metals differs between sites.