Toward predicting Dinophysis blooms off NW Iberia: a decade of events

Dinophysis acuminata and Dinophysis acuta are recurrent species off NW Iberia but their outbreaks occur under different conditions. A decade (2004-2013) of weekly data for each species at two sentinel stations located at the entrance of Rias de Aveiro-AV (NW Portugal, 40 degrees 38.6' N) and Pontevedra-PO (Galicia, Spain, 42 degrees 21.5' N), were used to investigate the regional synchronism and mesoscale differences related to species detection, bloom (>200 cells L-1) initiation and development. Results highlight the high interannual variability of bloom events and summarize the associated meteorological/oceanographic conditions. D. acuta blooms were observed in 2004-2008 and 2013, and the species highest maxima at AV occurred after the highest maxima of its prey Mesodinium, with a time-lag of 2-3 weeks. D. acuminate blooms were observed every year at both stations. The cell concentration time series shows that the blooms generally present a sequence starting in March with D. acuminata in PO and three weeks later in AV, followed by D. acuta that starts at AV and three months later in PO. Exceptionally, D. acuminate blooms occurred earlier at AV than PO, namely in high spring upwelling (2007) or river runoff (2010) years. A four-year gap (2009-2012) of D. acuta blooms occurred after an anomalous 2008 autumn with intense upwelling which is interpreted as the result of an equatorward displacement of the population core. Numerical model solutions are used to analyze monthly alongshore current anomalies and test transport hypotheses for selected events. The results show a strong interannual variability in the poleward/equatorward currents associated with changes in upwelling forcing winds, the advection of D. acute blooms from AV to PO and the possibility that D. acuminata blooms at AV might result from inocula advected southward from PO. However, the sensitivity of the results to vertical position of the lagrangian tracers call for more studies on species distribution at the various bloom stages. (C) 2015 Elsevier B.V. All rights reserved

Impact of delays on costumers'safety perceptions and behavioral intentions

Purpose: The main objective of this paper is to examine how the customers' perceptions of delays and safety relate to each other and to behavioral intentions Design/methodology/approach: We modified a customer satisfaction questionnaire to include questions relating to the constructs we wanted to examine and collaborated with a major international airline to collect data from 797 customers through in-flight surveys. Findings: We obtain three key original findings. First, perceived safety exerts a direct positive effect on behavioral intentions. Second, perceived delays exert an indirect effect mediated by perceived safety. Finally, customers believe operational practices affect both delay and safety. Originality/value: This is the first paper that examines the customer's perspective on two of the most important aspects of airline operations management: delays and safety. Our findings are of great value to managers who want to evaluate the impact of delays and safety on customers and to researches interested in the theoretical relationships between these two constructs.Peer Reviewe

Caracterização e aplicação de um gerador termoeléctrico

Mestrado em Engenharia MecânicaThis work is dedicated to the characterization of thermoelectric materials, as well as the simulation of their application and optimization by using a mathematical model. Thermoelectric generators are commonly used in space exploration for many decades, however their application can be extended to the recovery of exhaust gases in automobiles and industrial processes as well as the powering of different types of remote sensors. In this work, the BaGd2NiO5 material and its doping states with Ca were studied for the first time in terms of their thermoelectric properties such as Seebeck coefficient, thermal conductivity and electrical conductivity. A mathematical model was also developed to simulate the application performance of any thermoelectric material for various working conditions. After the experimental validation of the model it was used to simulate the performance of Ca0.15BaGd1.85NiO5 compound, which presented the best thermoelectric properties. The numerical simulations showed that the performance of a thermoelectric generator with this material would be as better as larger is the temperature difference that the module is subjected and as greater is the heat transfer from hot and cold sources to the thermoelectric generator. The electrical conductivity of Ca0.15BaGd1.85NiO5 is the main reason for its low viability since the conversion efficiency was much lower than 1% and the power output was also reduced. This work revealed that the doping of BaGd2NiO5 with Ca can improve its thermoelectric properties, such as the increasing of the electrical conductivity and the reduction of the thermal conductivity. Moreover, the optimization of the application showed to be important in terms of increasing the performance and reducing the material. The mathematical model permitted to conclude that the optimum thickness of the thermoelements will be as smaller as larger is the heat transfer coefficient by convection of the hot and cold fluids. The simulations with the mathematical were also useful to conclude that a generator with thermoelectric properties of Ca0.15BaGd1.85NiO5 could have a wide applicability if its electrical conductivity could be a hundred times greater than the current value.Este trabalho é dedicado à caracterização de materiais termoeléctricos, bem como a simulação da sua aplicação e otimização utilizando um modelo matemático. Os geradores termoeléctricos são utilizados com frequência na exploração espacial à várias décadas, no entanto a sua aplicação pode ser alargada à recuperação de gases de escape em automóveis e processos industriais, bem como na alimentação de diferentes tipos de sensores remotos. No presente trabalho, o material BaGd2NiO5 e seus estados de dopagem com Ca foram estudados pela primeira vez a nível das suas propriedades termoeléctricas tais como coeficiente de Seebeck, condutividade térmica e condutividade eléctrica. Um modelo matemático foi desenvolvido de forma a simular o desempenho da aplicação de um determinado material termoeléctrico para várias condições de trabalho. Após a validação experimental do modelo, o mesmo foi utilizado para simular o desempenho do composto Ca0.15BaGd1.85NiO5, o qual apresentou as melhores propriedades termoeléctricas. As simulações numéricas permitiram concluir que o desempenho de um gerador termoeléctrico com este tipo de material seria tanto melhor quanto maior for a diferença de temperaturas a que está sujeito e quanto maior for o coeficiente de transferência de calor por convecção das fontes quente e fria. A baixa condutividade eléctrica do material Ca0.15BaGd1.85NiO5 fez com que a viabilidade da sua utilização apresente algumas dificuldades uma vez que a sua eficiência será inferior a 1%, sendo a potência produzida igualmente reduzida. Este trabalho permitiu concluir que a dopagem do material BaGd2NiO5 com Ca poderá melhorar as suas propriedades termoeléctricas, nomeadamente com o aumento da condutividade eléctrica e com a redução da condutividade térmica. Por outro lado, a otimização da aplicação mostrou ser relevante em termos de aumento do desempenho e redução de material. O modelo matemático permitiu concluir que a espessura ótima dos elementos termoeléctricos será tanto menor quanto maior for o coeficiente de transferência de calor por convecção dos fluídos quente e frio. A partir do modelo matemático foi ainda possível concluir que um gerador com as propriedades de Ca0.15BaGd1.85NiO5 poderia ter uma grande aplicabilidade e se a sua condutividade eléctrica fosse cem vezes superior ao valor atual

A estrutura do sector bancário cabo-verdiano e a regulação do mercado

Cabo Verde, apesar de ser uma economia insular e desprovida de recurso naturais, tem sido característico dos países que conseguiu ter um razoável sucesso no processo de estabilização macroeconómica e solidez financeira, relativamente à região onde se encontra inserida, valendo-lhe a graduação para o país do nível de rendimento médio. O principal objectivo deste trabalho consiste em investigar e determinar empiricamente a estrutura do sector bancário cabo-verdiano, a sua regulação e supervisão, verificando assim, a paradigma da Estrutura-Comportamento-Resultados (E-C-R)1, bem como a sua contribuição para a solidez do todo sistema financeiro nacional. Na investigação, foi utilizado como fonte, a análise e o tratamento dos dados do Banco Central de Cabo Verde (BCV) e os estudos de um painel de balanços dos bancos comerciais caboverdianos, entre 2000 e 2011. O estudo centralizou-se basicamente nas quatro (4) maiores instituições bancárias (BCA, CECV, BI e BCN), o chamado mercado “onshore”, que representam mais de 80% do total do activo de sistema financeiro caboverdiano. Ficou claro que, a partir dos resultados encontrados (como Índice de Concentração e o de Herfindahl H), o mercado bancário cabo-verdiano é altamente concentrado, e com fraca volatilidade no tempo, apresentando assim características típicas da estrutura de mercado oligopolista, daí a análise de modelos teóricos mais complexos e bastante realista como a teoria da organização industrial bancária, com ênfase para modelos originais de Klein-Monti, de Cournot, Bertrand e Steckelberg. Por fim, procurou-se fazer a abordagem nas chamadas políticas de Regulação e Supervisão, definidas e supervisionadas pelo BCV, que em função desta, exerce as suas atribuições nos mercados de capitais mobiliários e seguros, actuando segundo o modelo Monista.Cape Verde, despite being an island economy and devoid of natural resources, has been characteristic of the countries that could have a reasonable success in stabilizing macroeconomic and financial strength, to the region where it is inserted, is using his progression to developing country medium. The main objective of this work is to investigate and determine empirically the structure of the banking sector in Cape Verde, the regulation and supervision of this market, thus verifying the paradigm of Structure-Behavior-Results (S-B-R)2, as well as its contribution to the strength the whole financial system. To start the work, was used as the source, processing and analysis of data from Central Bank of Cape Verde (BCV) and studies of a panel of balances of commercial banks operating in the Cape Verdean market between 2000 and 2011. The study was centered primarily in four (4) major national banks (BCA, CECV, BI and BNC), the market called "onshore", which represent more than 80% of total assets of the financial system in Cape Verde. It was clear that, based on the results found (such as Concentration Index and Herfindahl H), the Cape Verdeian banking market is highly concentrated, with low volatility in time, thus presenting typical characteristics of the oligopolistic market structure, hence the analysis of more complex theoretical models and quite realistic as the theory of banking industry organization, with emphasis on original models of Klein-Monti, Cournot, Bertrand and Steckelberg. Finally, it was tried to approach the so-called Regulation and Supervision policies, defined and supervised by the BCV, which, in function of this, exercises its attributions in the securities and insurance capital markets, acting according to the Monista model

Habitat amount and ambient temperature dictate patterns of anuran diversity along a subtropical elevational gradient

Aim: Patterns of diversity along elevational gradients are driven by species characteristics but remain poorly understood. Filling this gap is imperative given the deteriorating conservation status of anurans worldwide. Here, we examine frog diversity and species composition along a sharp subtropical elevational gradient and assess the degree to which these are determined by environmental and spatial predictors. Location: An extensive southern Brazilian Atlantic Forest elevational gradient ranging from 300 to 1,800 m above sea level. Methods: We sampled 38 ponds and used structural equation modelling to examine the direct and indirect effects of area, climate, habitat amount, habitat complexity and productivity on frog species richness and abundance. We also applied joint species distribution models to investigate the importance of these predictors on frog species composition using species distribution and co-occurrence along the elevational gradient. Results: We recorded 12,636 individuals of 41 frog species. Frog species richness was highest at intermediate elevations, showing a hump-shaped pattern. Frog abundance was highest at lowlands and decreased towards higher elevations. We found support for only the habitat amount hypothesis in explaining overall species richness. Although temperature had a positive influence on productivity and frog abundance, neither predictors were related to species richness. Species composition diverged markedly between lowland and highland frog assemblages, which was mainly attributed to differences in ambient temperature. Main conclusion: Elevations containing more extensive natural habitat areas retained the most species-rich frog assemblages. The mid-elevational peak is likely attributed to lowland habitat (1,400 masl). The entire elevational gradient is, however, critical in maintaining anuran species diversity as lowland assemblages are distinct from those at mid- to high elevations. Our study also shows that anthropogenic habitat loss has a decisive effect on montane frog diversity, reinforcing the need to effectively protect these areas

Measuring user influence in financial microblogs: experiments using stocktwits data

In this paper, we study the effect of graph structure user in- fluence measures in financial social media. In particular, we explore rich and recent data, composed of 1.2 million Stock- Twits messages, from June 2010 to March 2013. These data allow the creation of social network graphs by considering direct active interactions (retweets, shares or replies). Using such graphs and a realistic rolling windows evaluation, we analyzed four user influence measures (indegree, between- ness, page rank and posts) under two criteria: Percentage of Quality Users (PQU), as manually labeled by StockTwits; and the daily sentiment correlation between top lists of in- fluential users and other users. The sentiment was based on a StockTwits labeled dataset and assessed in terms of three selections: overall sentiment (ALL) and filtered by two ma- jor technological companies (Apple – AAPL and Google – GOOG). Promising results were obtained, with several top lists pre- senting PQU values higher than 80% and correlations higher than 0.6. Overall, the best results were achieved by the page rank and posts measures.This work has been supported by COMPETE: POCI-01- 0145-FEDER-007043 and FCT { Funda c~ao para a Ci^encia e Tecnologia within the Project Scope: UID/CEC/00319/2013. We also thank StockTwits for the provision of their data

Análise Estática de Vigas Isotrópicas Apoiadas em Base Elástica Winkler-Pasternak

Beams resting on elastic foundations are widely used in engineering projects, so analyzing their displacement fields is very important. The present work presents solutions for the deflection of isotropic beams resting on elastic foundations of the Winkler-Pasternak type. The proposed formulation is based on the Euler-Bernoulli beam theory, and the governing equations and the boundary conditions are derived from the principle of virtual work. The direct integration method can decouple the deflections from axial displacement and twists. The system of deflection equations decouples into two principal directions and is transformed into a first-order system. The solution of this system of equations is obtained through the method of variation of parameters. When analyzing the results of the maximal deflections, it is observed that increasing values of the foundation stiffness provide decreasing deflections and that the influence of the Pasternak parameter is more significant on the results than that of the Winkler parameter.Vigas apoiadas em fundações elásticas são amplamente utilizadas em projetos de engenharia, logo analisar os deslocamentos sofridos por elas é muito importante. Por isso, o presente trabalho apresenta soluções para a deflexão de vigas isotrópicas sobre fundações elásticas do tipo Winkler-Pasternak. A formulação proposta é baseada na teoria de vigas de Euler-Bernoulli e as equações que descrevem o problema e as condições de contorno são derivadas do princípio do trabalho virtual. O método de integração direta é utilizado para desacoplar as deflexões do deslocamento axial e da torção. O sistema de equações desacopladas de deflexão em duas direções principais é transformado em um sistema de primeira ordem. A solução deste sistema de equações é obtida através do método de variação de parâmetros. Ao analisar os resultados das deflexões máximas, observa-se que com o aumento dos valores de rigidez de fundação, os deslocamentos de flexão diminuem e que o parâmetro de rigidez de Pasternak tem maior influência aos resultados que a rigidez de Winkler