1,416 research outputs found

    Estimativa das idades das árvores numa floresta natural invadida na ilha de São Miguel, Açores

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    Dissertação de Mestrado, Biodiversidade e Biotecnologia Vegetal, 2 de Dezembro de 2016, Universidade dos Açores.As florestas naturais ocupam cerca de 10% da superfície terrestre nos Açores. Um aspeto que merece maior atenção é a determinação da idade das árvores em florestas naturais, uma vez que permitiria uma mais completa compreensão da dinâmica florestal. Foi analisada a estrutura da floresta e estimada a idade das árvores através da altura do peito em dois talhões de floresta laurifólia localizados na “Área Protegida para a Gestão de Habitats ou Espécies da Serra de Água de Pau” (SMG07, Parque Natural da Ilha de São Miguel), localizada a 569 (ST1) e 612 m (ST2). Utilizou-se o método de amostragem “T-Square” para estimar a densidade das árvores e mediu-se a altura das árvores, o diâmetro basal e o volume de copa. As amostras de madeira foram colhidas à altura do peito, utilizando a sonda de Pressler, e tratadas, para permitir a contagem dos anéis anuais de cada espécie. Na ST1 Morella faya foi a espécie mais frequente, sendo também a que apresentou maior área basal, contudo foi superada em biovolume por Pittosporum undulatum; Na ST2 Erica azorica, Ilex azorica e Laurus azorica foram mais frequentes, e L. azorica obteve maiores valores de área basal, mas P. undulatum apresentou um biovolume idêntico. A idade da árvore à altura do peito, na ST1 variou entre 10-52 anos para L. azorica, 15-82 anos, para M. faya e 34-79 anos para P. undulatum; na ST2 as idades das árvores variaram entre 10-39 anos para L. azorica, 17-38 anos para I. azorica, 9-31 anos para E. azorica, 13-34 anos para M. faya, e 29 e 51 anos para duas amostras de P. undulatum. O solo da floresta estava praticamente coberto por Hedychium gardnerianum e raramente foram encontrados plântulas ou plantas jovens. Este estudo também revelou diferentes tipos de padrões de anéis de crescimento para as diferentes espécies. Este é um dos primeiros estudos que revela as idades das árvores numa floresta laurifólia nos Açores.ABSTRACT: Natural forests have been estimate to occupy about 10% of the land surface in the Azores. One aspect that merits further attention is tree age determination in natural forests. This would allow a more complete understanding of temporal forest dynamics. We analyzed forest structure and estimated tree age at breast height at two stands of laurel forest located at the “Área Protegida para a Gestão de Habitats ou Espécies da Serra de Água de Pau” (SMG07, Parque Natural da Ilha de São Miguel), located at 569 (ST1) and 612 m (ST2). We used T-square sampling to estimate tree density and measured tree height, basal diameter and canopy volume. A Pressler borer was use to collect wood samples at breast height that were treated to allow annual tree ring counting. At ST1 Morella faya was the most frequent tree species and had the largest basal area but was surpassed in biovolume by Pittosporum undulatum; At ST2 Erica azorica, Ilex azorica and Laurus azorica were most frequent, L. azorica showed the largest basal area but P. undulatum equaled its biovolume. Tree ages at breast height, at ST1 ranged 10-52 years in L. azorica, 15-82 years in M. faya, and 34-79 years in P. undulatum; at ST2 tree ages ranged 10-39 years in L. azorica, 17-38 years for Ilex azorica, 9- 31 years for E. azorica, 13-34 years for M. faya, and 29-51 years for two specimens of P. undulatum. Forest soil was almost completely covered by Hedychium gardnerianum therefore seedlings and saplings were seldom found. This research also revealed different types of annual ring patterns for the different taxa. This is one of the first studies revealing tree age at a laurel forest stand in the Azores

    As principais motivações de turistas gastronómicos para o consumo de comida local em Portugal

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    Culinary tourism is becoming an emergent alternative to mass tourism. In the literature, different motivations have been recognized to affect the choice of tourists to experience local food. Taking this into consideration, the purpose of this study is to understand the motivational factors that lead to the consumption of local food and beverages in the geographical setting of Portugal. To test this, a modified version of Kim and Eves (2012) motivational scale was used. Data was collected via an online survey from domestic and international tourists who have been to Portugal in the past, and 190 responses were obtained, from which 162 were considered valid. The data were analysed using the statistical software IBM SPSS, and multivariate regression analysis was used to determine if the seven variables in question influenced the frequency of consumption of local gastronomy in Portugal. The results revealed that cultural experience, excitement, interpersonal relationships, sensory appeal, health concerns and prestige are all motivational factors that lead to the consumption of local food, while social and environmental sustainability is not found to motivate tourists. The present study has interesting implications for managers and marketers working within the food and tourism industry.O turismo culinário está a tornar-se uma alternativa emergente no turismo de massas. Na literatura, foram reconhecidas diferentes motivações que influenciam a escolha dos turistas a experimentar e provar a comida local. Tendo isto em consideração, este estudo propõe-se a compreender os fatores motivacionais que levam ao consumo de alimentos e bebidas locais no contexto geográfico de Portugal. Para testar isto, foi utilizada uma versão modificada da escala motivacional de Kim & Eves (2012). Os dados foram recolhidos através de um inquérito online administrado a turistas nacionais e internacionais que visitaram Portugal no passado, e foram obtidas 190 respostas, das quais 162 foram consideradas válidas. Os dados foram analisados utilizando o software estatístico IBM SPSS, e a análise de regressão multivariada foi utilizada para determinar se as sete variáveis em questão têm influência na frequência do consumo da gastronomia local em Portugal. Os resultados revelam que a experiência cultural, entusiasmo, relações interpessoais, apelo sensorial, preocupações de saúde e prestígio são fatores motivadores que levam ao consumo de alimentos locais, enquanto a sustentabilidade social e ambiental não é suportada como motivação para o consumo. O presente estudo tem implicações interessantes para os gestores e marketers que trabalham na indústria alimentar e turística.Mestrado em Gestã

    Design of a Monosized Droplet Generator

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    This dissertation focuses on the development and validation of an instrument that allows the formation of drops. This document starts by showing the design developed for this purpose. After the development of the design, the pieces were built using 3D printing. When the process was complete, the device was assembled and validated. For the validation of this instrument, it was necessary to create a test station which is shown in chapter 3. After the entire assembly process, the validation tests were carried out. In the validation phase, water was applied to be ejected by the apparatus. Six different flow rates were implemented in order to determine the effect of the flow rate on the formation and behavior of the drops. The results of these tests were obtained through visualization methods. After all the images were collected in the testing phase, they were analyzed for the extraction of diameters. After the tests of undisturbed droplet formation were completed, the disturbed generation of droplets was proceeded to test. In this testing phase, three flows were chosen from the previous phase and imposed. The flow rates chosen for the disturbed phase of the generation of droplets were: 2.5, 4 and 5 ml/min. The proceedings for these tests was the flow and signal implementation. After the flow was implemented, the electromagnetic wave was built to be implemented in the piezoelectric cell. The electromagnetic signal consists of a square wave of constant amplitude (20 Vpp), where the frequency is periodically increased. The study with several frequencies aims to investigate the influence of frequency on the forma- tion of drops for the case of this instrument. This study allows testing whether the apparatus is capable of creating consecutive drops with high repeatability in terms of diameter and spacing between drops. Like the undisturbed cases, the disturbed droplet formation was also tested through visualization and image analysis.Esta dissertação foca-se no desenvolvimento e validação de um instrumento que permite a for- mação de gotas. Este documento começa por mostrar o design desenvolvido para este propósito. Após o desenvolvimento do design, as peças foram construídas recorrendo à impressão 3D. Após a impressão das peças, procedeu-se à montagem e validação do dispositivo. Para a validação deste instrumento, foi necessário criar uma estação de testes que é mostrada no capítulo 3. Após todo o processo de montagem, realizaram-se os testes de validação. Na fase de validação, usou-se água para a validação do aparelho. Seis caudais diferentes foram implementados, de forma a determinar o efeito do caudal na formação e comportamento das gotas. Os resultados destes testes foram obtidos através de métodos de visualização. Após todas as imagens serem recolhidas na fase de testes, estas foram analisadas para a extracção de diâmetros. Depois deste processo ter sido concluido, procedeu-se a testar a geração de gotas perturbada. Nesta fase de testes, três caudais foram escolhidos de entre os im,postos na primeira fase de validação e impostos. Os caudais escolhidos para a fase perturbada da geração de gotas foram: 2.5, 4 e 5 ml/min. O procedimento para estes testes foi a implementação do caudal e do sinal. Após a implementação do caudal, a onda electromagnética foi construída para implementar na célula piezoeléctrica. O sinal electromagnético consiste numa onda quadrada de amplitude constante (20 Vpp), onde a frequência é periodicamente aumentada. O estudo com várias frequências visa a investigação da influência da frequência na formação de gotas para o caso deste instrumento. Este estudo permite testar se o aparato é capaz de criar gotas consecutivas com alta repetibilidade no que toca a diâmetros e espaçamento entre gotas. À semelhança dos casos não perturbados, a formação perturbada de gotas também foi testada através de visualização e análise de imagem

    Enzymatic activity mastered by altering metal coordination spheres

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    J Biol Inorg Chem (2008) 13:1185–1195 DOI 10.1007/s00775-008-0414-3Metalloenzymes control enzymatic activity by changing the characteristics of the metal centers where catalysis takes place. The conversion between inactive and active states can be tuned by altering the coordination number of the metal site, and in some cases by an associated conformational change. These processes will be illustrated using heme proteins (cytochrome c nitrite reductase, cytochrome c peroxidase and cytochrome cd1 nitrite reductase), non-heme proteins (superoxide reductase and [NiFe]-hydrogenase), and copper proteins (nitrite and nitrous oxide reductases) as examples. These examples catalyze electron transfer reactions that include atom transfer, abstraction and insertion

    Improving the matching of registered unemployed to job offers through machine learning algorithms

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    Dissertation presented as the partial requirement for obtaining a Master's degree in Information Management, specialization in Knowledge Management and Business IntelligenceDue to the existence of a double-sided asymmetric information problem on the labour market characterized by a mutual lack of trust by employers and unemployed people, not enough job matches are facilitated by public employment services (PES), which seem to be caught in a low-end equilibrium. In order to act as a reliable third party, PES need to build a good and solid reputation among their main clients by offering better and less time consuming pre-selection services. The use of machine-learning, data-driven relevancy algorithms that calculate the viability of a specific candidate for a particular job opening is becoming increasingly popular in this field. Based on the Portuguese PES databases (CVs, vacancies, pre-selection and matching results), complemented by relevant external data published by Statistics Portugal and the European Classification of Skills/Competences, Qualifications and Occupations (ESCO), the current thesis evaluates the potential application of models such as Random Forests, Gradient Boosting, Support Vector Machines, Neural Networks Ensembles and other tree-based ensembles to the job matching activities that are carried out by the Portuguese PES, in order to understand the extent to which the latter can be improved through the adoption of automated processes. The obtained results seem promising and point to the possible use of robust algorithms such as Random Forests within the pre-selection of suitable candidates, due to their advantages at various levels, namely in terms of accuracy, capacity to handle large datasets with thousands of variables, including badly unbalanced ones, as well as extensive missing values and many-valued categorical variables

    Contributos para o estudo da biblioteca particular de José do Canto

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    Dissertação de Mestrado, Tradução e Assessoria Linguística, 23 de Maio de 2016, Universidade dos Açores.O presente trabalho tem como principal objetivo o conhecimento das influências culturais que marcaram a sociedade açoriana do século XIX, através do estudo da coleção bibliográfica de José do Canto, com especial enfoque nas obras em língua estrangeira e obras traduzidas. O estudo terá como ponto de partida os fundamentos teóricos dos Estudos da Tradução preconizados por Susan Bassnett, que coloca a tónica numa abordagem cultural da tradução em detrimento de uma abordagem focalizada em aspetos linguísticos. No caso em análise, será observado um período crucial para o desenvolvimento de São Miguel, correspondendo à segunda metade do século XIX. As obras selecionadas servirão de ponto de partida para se conhecer o papel da tradução para satisfazer o desejo de conhecimento e aferir o papel das influências estrangeiras que terão marcado a figura de José do Canto e as preocupações da sua época. Ao mesmo tempo, procurar-se-á compreender o grau de consciência que os tradutores tinham das especificidades da sua atividade e divulgar o ainda pouco conhecido património cultural de José do Canto, espelhado na sua vasta biblioteca particular.ABSTRACT: The following work is primarily focused on the knowledge of the cultural influences that shaped the Azorean society in the 19th century, through the study of the personal book collection that belonged to José do Canto, with special emphasis on foreign language books and translated books. The study takes as its starting point the theoretical principles of Translation Studies defended by Susan Bassnett, which bring attention to a cultural approach rather than a linguistic-based approach. In this particular case, it will focus on the second half of the 19th century, a crucial period for the development of São Miguel Island. The selected works will provide the textual body both to assess how translation participated in fulfilling the desire for knowledge and to understand to what extent foreign influences marked José Canto and his time. Furthermore, this study intends to perceive the degree of awareness of translators regarding the specific nature of their activity and to contribute to the dissemination of the almost unknown cultural heritage of José do Canto that is reflected in his vast personal book collection

    The tetranuclear copper active site of nitrous oxide reductase: the CuZ center

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    J Biol Inorg Chem (2011) 16:183–194 DOI 10.1007/s00775-011-0753-3This review focuses on the novel CuZ center of nitrous oxide reductase, an important enzyme owing to the environmental significance of the reaction it catalyzes, reduction of nitrous oxide, and the unusual nature of its catalytic center, named CuZ. The structure of the CuZ center, the unique tetranuclear copper center found in this enzyme, opened a novel area of research in metallobiochemistry. In the last decade, there has been progress in defining the structure of the CuZ center, characterizing the mechanism of nitrous oxide reduction, and identifying intermediates of this reaction. In addition, the determination of the structure of the CuZ center allowed a structural interpretation of the spectroscopic data, which was supported by theoretical calculations. The current knowledge of the structure, function, and spectroscopic characterization of the CuZ center is described here. We would like to stress that although many questions have been answered, the CuZ center remains a scientific challenge, with many hypotheses still being formed

    The electron transfer complex between nitrous oxide reductase and its electron donors

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    J Biol Inorg Chem (2011) 16:1241–1254 DOI 10.1007/s00775-011-0812-9Identifying redox partners and the interaction surfaces is crucial for fully understanding electron flow in a respiratory chain. In this study, we focused on the interaction of nitrous oxide reductase (N2OR), which catalyzes the final step in bacterial denitrification, with its physiological electron donor, either a c-type cytochrome or a type 1 copper protein. The comparison between the interaction of N2OR from three different microorganisms, Pseudomonas nautica, Paracoccus denitrificans, and Achromobacter cycloclastes, with their physiological electron donors was performed through the analysis of the primary sequence alignment, electrostatic surface, and molecular docking simulations, using the bimolecular complex generation with global evaluation and ranking algorithm. The docking results were analyzed taking into account the experimental data, since the interaction is suggested to have either a hydrophobic nature, in the case of P. nautica N2OR, or an electrostatic nature, in the case of P. denitrificans N2OR and A. cycloclastes N2OR. A set of well-conserved residues on the N2OR surface were identified as being part of the electron transfer pathway from the redox partner to N2OR(Ala495, Asp519, Val524, His566 and Leu568 numbered according to the P. nautica N2OR sequence). Moreover, we built a model for Wolinella succinogenes N2OR, an enzyme that has an additional c-type-heme-containing domain. The structures of the N2OR domain and the c-type-heme-containing domain were modeled and the full-length structure was obtained by molecular docking simulation of these two domains. The orientation of the c-type-heme-containing domain relative to the N2OR domain is similar to that found in the other electron transfer complexes
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