Adequacy analysis of learning resources in adult education

Dissertação de mestrado integrado em Engenharia InformáticaThe present document identifies and details the research and development held under the scope of a MSc Thesis pertaining to the scientific area of pedagogic tools for teaching support, ontolo gies and learning resources. This masters thesis in Informatics Engineering was developed in the University of Minho, Braga. The purpose of the project is to study the learning process of adults and how it connects to Learn ing Resources (LRs) in order to understand if a learning resource used to teach Computational Thinking (CT) to children, is suitable for adult learners. This approach ought to take into account adult learning theory to set its requirements, as well as CT principles and learning resources classification. To this end, an approach to the Adequacy of Learning Resources in Adult Education was created which comprises the ontology OntoAL that describes in detail the domain of Adult Learning (AL) including the theory of AL and a classification of both the adult learner and the learning resources. This ontology was developed in OntoDL and Prolog. In addition, we analyze the experiment conducted as part of the validation of this approach and the OntoAL ontology. Therefore, in this document, it is presented the state of the art pertaining to this field, exploring the concepts of learning resources, computational thinking, ontologies and adult learning and education. Furthermore, it is rendered an introduction of the subject and the project, detailing the context of the problem, the objectives to be accomplished and the research hypothesis of said thesis. Next, it is presented the state of the art regarding Computational Thinking, Adult Learning and Education, Ontologies and Learning Resources. Thereafter, it is put forward the work proposal. Then it is introduced the OntoAL ontology in both OntoDL and Prolog (detailing the process of its development and the choices made), the questionnaires that were created as well as the analysis of the responses that we obtained. Lastly, there are listed the conclusions and the future work.O presente documento identifica e detalha a investigação e desenvolvimento realizados no âmbito de uma tese de mestrado relativa à área científica de ferramentas pedagógicas de apoio ao ensino, ontologias e recursos educativos. Esta tese de mestrado em Engenharia Informática foi desenvolvida na Universidade do Minho, Braga. O objectivo do projecto é estudar o processo de aprendizagem dos adultos e como este se relaciona com os Recursos Educativos (RE), de modo a compreender se um recurso educativo utilizado para ensinar Pensamento Computacional (CT) a crianças, é adequado para alunos adultos. Esta abordagem deve ter em conta a teoria de ensino de adultos para estabelecer os seus requisitos, bem como os princípios de CT e a classificação dos recursos educativos. Neste sentido foi criada uma abordagem à Adequação de Recursos Educativos na Educação de Adultos que contém a ontologia OntoAL que descreve em detalhe o domínio do Ensino de Adultos (EA) incluindo a teoria de EA e uma classificação tanto do aluno adulto como dos recursos educativos. Esta ontologia foi desenvolvida em OntoDL e Prolog. Para além disso, analisamos a experiência levada a cabo como parte da validação desta abordagem e da ontologia OntoAL. Por conseguinte, neste documento, é apresentado o estado da arte neste campo, explorando os conceitos de recursos educativos, pensamento computacional, ontologias e educação de adultos. Além disso, é feita uma introdução ao tema e ao projecto, detalhando o contexto do problema, os objectivos a alcançar e a hipótese de investigação da referida tese. A seguir, é apresentado o estado da arte em matéria de Pensamento Computacional, Ensino e Educação de Adultos, Ontologias e recursos educativos. Em seguida, é descrita a proposta de trabalho, a ontologia OntoAL desenvolvida em OntoDL e em Prolog (detalhando o processo do seu desenvolvimento e as escolhas feitas), os questionários que foram criados, e a análise das respostas obtidas. Finalmente, são listadas as conclusões bem como o trabalho futuro

Diversity of cover crops in two organic vineyards in the Niagara Region, Canada, as an adaptation measure to climate change

Vineyards are agroecosystems of great importance in the Niagara Region, Ontario (Canada). Due to its microclimate, this region is projected to be impacted by climate change with temperature increases, changes in precipitation patterns in all seasons, and greater frequency of extreme weather events. The aim of this thesis was to explore the projected changes for the weather in the Niagara Region, Canada, summarize which seasonal changes are expected and assess how such changes are likely to affect the key components of the vineyard ecosystem (i.e., soil, vines, invertebrates, and pathogens). It is expected that by 2080 the region will experience an increase in temperature in all four seasons; an increase in precipitation during the fall, winter, and spring; and a decrease in precipitation during summer months. Impacts of the projected changes will likely lead to vine water stress, yield loss, increases in incidents of diseases, increases in the spread of new pests, and changes in grape quality ultimately resulting in lower wine quality and/or production. Current management practices will need to be better understood and adaptive strategies introduced to enhance grape growers’ ability to minimize these impacts. The research also aimed to test the performance of four different cover crops in monoculture or in mixture in two organic vineyards. Of the planted species, rye grass and hairy vetch showed a great establishment, while pearl millet did not establish due to weed pressure. The ecological indexes (Shannon, Simpson’s, and Evenness) values showed that there is significant difference in cover crop diversity between growing seasons and collection months (June/September) in Vineyard #2, and in richness in Vineyard #1, indicating fluctuations in community composition over time. These results suggest a dynamic ecosystem response to seasonal and annual variations. These results may be used to increase the knowledge about the expected future for the vineyards in the region in face of climate change, and into one of the alternative management techniques that can help mitigate the impacts of changes in temperature and rainfall increase of extreme events in the region

Models for the price of a storable commodity

The current literature does not provide efficient models for commodity prices and futures valuation. This inadequacy is partly due to the fact that the two main streams of the literature - structural models and reduced form models - are largely disjoint. In particular, existing structural models are developed under rigid discrete time framework that does not take into account the mean-reverting properties of commodity prices. Furthermore, most of the literature within this class does not analyze the properties of the futures prices. Current reduced-form models allow cash-and-carry arbitrage possibilities and do not take into account the dependence between the spot price volatility and the inventory levels. This thesis investigates three new models for the price of a storable commodity and futures valuation. Specifically, we develop a structural model and two reduced-form models. In doing so, we expand the leading models within each of the two streams of the literature, by establishing a link between them. Each of these models provide an advance of their type. This study makes several contributions to the literature. We provide a new structural model in continuous time that takes into account the mean reversion of commodity prices. This model is formulated as a stochastic dynamic control problem. The formulation provided is flexible and can easily be extended to encompass alternative microeconomic specifications of the market. The results provide an optimal storage policy, the equilibrium prices and the spot price variability. We also develop a numerical method that allows the construction and analysis of the forward curves implied by this model. We provide a separate analysis considering a competitive storage and considering a monopolistic storage. The results are consistent with the theory of storage. Furthermore, the comparison between monopoly and competition confirm the economic theory. We developed a simple reduced-form model that focuses both on the mean reverting properties of commodity prices and excludes cash-and-carry arbitrage possibilities. This model is compared with a standard single-factor model in the literature. This new model adds two important features to the standard model and motivates the development of a more sophisticated reduced-form model. Accordingly, the last model developed in this thesis is a reduced-form model. It is a two-factor model that represents the spot price and the convenience yield as two correlated stochastic factors. This model excludes cash-and-carry arbitrage possibilities and takes into account the relationship between the spot price volatility and the inventory level. We find an analytical solution for the futures prices. This model is tested empirically using crude oil futures data and it Is compared with one of the leading models in the literature. Both models are calibrated using Kalman filter techniques. The empirical results suggest that both models need to be improved in order to better fit the long-term volatility structure of futures contracts

Apadrinhamento civil

Dissertação apresentada à Faculdade de Direito da Universidade de Coimbra para obtenção do grau de Mestre em Direito na Especialidade em Ciências Jurídico-Forense

The role of fitness frequency-dependent in the evolution of antibiotic resistance

Tese de mestrado. Biologia (Microbiologia Aplicada). Universidade de Lisboa, Faculdade de Ciências, 2010Antibiotic resistance is, usually, associated with fitness costs for the bacteria. Therefore, it is expected that if one competes a resistant bacterial strain with an otherwise isogenic susceptible strain in an antibiotic free environment, resistant bacteria will be eliminated. Here, I report the occurrence of stabilizing frequency-dependent selection in 43% of a set of antibiotic resistant strains. Stabilizing frequency-dependent selection may promote the maintenance of a stable polymorphism between resistant and susceptible bacteria. If resistant bacteria are rare, their fitness is higher than that of the susceptible strain. If resistant bacteria are the majority in the competition assay, their fitness is smaller than that of the susceptible strain. This enables a stable coexistence between sensitive and resistant strains. Genetic and ecological causes of frequency-dependent selection were investigated. The demonstration of frequency-dependent selection involving drug resistance strains implies that antibiotic resistant bacteria will not be easily eliminated or reversed upon reduction of antibiotic use. This reveals a worrying scenario for the eradication of antibiotic resistance.Durante muito tempo foi admitido que as populações bacterianas seriam mantidas num estado monomórfico devido a dois fenómenos: competição exclusiva e selecção periódica. O principio da exclusão competitiva refere que duas ou mais espécies que competem pelos mesmos recursos não podem coexistir, uma vez que a espécie mais eficiente irá eliminar gradualmente todas as outras (Hardin, 1960). O processo de selecção periódica, em que a evolução de populações bacterianas num recurso limitante consiste numa série temporal de substituições por genótipos cada vez com maior sucesso reprodutivo ou fitness, é responsável por eliminar toda a variabilidade genética (Atwood, et al., 1951, Levin, 1981). A existência de polimorfismos seria, então, apenas uma etapa transitória no processo evolutivo. Contudo, o processo de competição entre espécies é muito mais complexo. O ambiente dos organismos, biótico e físico, é heterogéneo espacial e temporalmente. Portanto, as frequências dos diferentes genótipos numa população estão continuamente a sofrer alterações. Ao mesmo tempo, existem mecanismos responsáveis pela manutenção de polimorfismos nas populações bacterianas. A selecção dependente da frequência é um desses mecanismos. A selecção dependente da frequência já foi observada em organismos como Drosophila (Ayala, 1971), Escherichia coli (Levin, 1972, Helling, et al., 1987) e em vírus (Elena, et al., 1997, Yuste, et al., 2002). Num sistema biológico, em que a selecção dependente da frequência actua, o sucesso reprodutivo de um organismo está dependente da sua frequência. Este mecanismo pode resultar em dois cenários diferentes. Assim sendo, a selecção pode favorecer o genótipo mais comum, definindo-se como selecção dependente da frequência disruptiva. Por outro lado, se a selecção favorecer o genótipo mais raro, então estamos perante selecção dependente da frequência estabilizante. A selecção dependente da frequência disruptiva leva à eliminação de polimorfismos na população. Um genótipo, mesmo possuindo uma qualquer vantagem, apenas será seleccionado face a outro genótipo se a sua frequência se encontrar acima de um certo valor (Levin, 1988). Caso contrário, o genótipo é eliminado. A selecção dependente da frequência estabilizante, sobre a qual nos iremos focar neste trabalho, resulta num ponto de equilíbrio que permite a coexistência estável entre os genótipos. Se a frequência de um dos genótipos está abaixo do equilíbrio estável, o seu fitness relativamente ao outro genótipo será maior, permitindo-lhe aumentar a sua frequência. Se a sua frequência estiver acima do ponto de equilíbrio, o seu fitness será menor do que o outro genótipo em competição, e consequentemente irá ocorrer uma redução do seu número. No ponto de equilíbrio o fitness de ambos os genótipos é idêntico, levando a um polimorfismo estável. Vários estudos demonstram a coexistência de genótipos diferentes mesmo em ambientes simples. Algumas sugestões foram sendo dadas na tentativa de explicar os mecanismos ecológicos que permitem a coexistência: (i) Trade-off demográfico, em que cada genótipo é especializado num diferente nicho ecológico (Levin, 1972, Helling, et al., 1987, Turner, et al., 1996, Rozen & Lenski, 2000). Por exemplo, um dos genótipos possui um maior fitness quando a glucose no meio é abundante, enquanto o outro genótipo possui um fitness mais elevado quando a glucose é escassa (Turner, et al., 1996); (ii) Cross-feeding, em que o genótipo com maior sucesso excreta um metabolito resultante do seu metabolismo ou morte celular para o meio. O segundo genótipo é eficiente a utilizar este metabolito (Turner, et al., 1996, Rozen & Lenski, 2000); (iii) Interacção antagonista, em que durante a fase estacionária um dos genótipos devido a uma mutação ou a um efeito pleiotrópico de uma mutação é capaz de inibir o genótipo mais frequente, interferindo com o seu crescimento máximo (Lemonnier, et al., 2008). Os mecanismos ecológicos acima descritos não se excluem entre si. Aliás, a ocorrência de um trade-off demográfico está geralmente associado a uma interacção por cross-feeding (Rosenzweig, et al., 1994, Turner, et al., 1996). No presente estudo demonstro a ocorrência de selecção dependente da frequência em bactérias resistentes a antibióticos. A resistência aos antibióticos pode resultar de mutações genéticas e/ou aquisição de determinantes de resistência por transferência horizontal de genes (revisto emMartinez, et al., 2009). As mutações que conferem resistência podem alterar processos fisiológicos da célula (Andersson & Levin, 1999). De forma similar, quando a resistência está localizada em elementos genéticos móveis (plasmídeos, integrões ou transposões), a replicação e expressão dos seus genes é responsabilidade da bactéria hospedeira. Tal irá interferir no crescimento normal da bactéria (Bjorkman & Andersson, 2000). Assim, um fenótipo resistente acarreta na maioria das vezes, custos para a bactéria, fazendo com que sofra uma diminuição do seu fitness (Andersson, 2006). Neste trabalho, utilizei bactérias resistentes a três antibióticos diferentes: ácido nalidíxico, rifampicina e estreptomicina. Para estes antibióticos a resistência é causada por mutações cromossomais em genes envolvidos na replicação (Marcusson, et al., 2009) , transcrição (Reynolds, 2000) e tradução (Kurland, et al., 1996), respectivamente. Estudos anteriores têm demonstrado que, face às alterações fisiológicas inerentes à resistência, bactérias resistentes em competição com bactérias sensíveis e na ausência de antibióticos, possuem uma desvantagem competitiva (Gillespie, 2001, Trindade, et al., 2009). Deste modo, a simples redução no uso de antibióticos deveria erradicar o grave problema das resistências aos antibióticos. Ou seja, as estirpes resistentes seriam eliminadas. Contudo, o cenário apresenta-se muito mais complexo (Johnsen, et al., 2009). Existem vários processos que permitem manter bactérias resistentes na população ao reduzirem ou eliminarem o custo provocado pelas mesmas: mutações compensatórias (Bjorkman & Andersson, 2000), epistasia entre resistências a antibióticos (Trindade, et al., 2009), mutações sem custo (Ramadhan & Hegedus, 2005, Criswell, et al., 2006) e co-selecção de resistências a antibióticos (Enne, et al., 2004, Andersson & Hughes, 2010). A ocorrência de selecção dependente da frequência aqui apresentada poderá ser um outro fenómeno. Os resultados aqui apresentados mostram que 13 dos 30 clones espontâneos (43%) resistentes a antibióticos testados apresentam um fenótipo de dependência na frequência quando em competição com um clone sensível. É de notar que, para as mesmas mutações pontuais nos genes envolvidos na resistência ao antibiótico respectivo, os clones resistentes apresentavam um comportamento diferente durante a competição. Isto sugere que o fenótipo para a dependência na frequência seria causado, não pelas mutações para a resistência, mas por outra qualquer mutação a ocorrer no cromossoma. Contudo, tal hipótese não ficou demonstrada. Relativamente, ao mecanismo ecológico responsável pela dependência na frequência sugeri a ocorrência de um cross-feeding ou uma interacção antagonista. Relativamente, ao cross-feeding os resultados não foram esclarecedores. No entanto, a hipótese de uma interacção antagonista, apesar de ainda não testada, aponta-se esclarecedora: os clones resistentes seriam portadores de uma mutação capaz de inibir os clones sensíveis através de um contacto célula a célula. Os resultados mostram uma incidência elevada de selecção dependente da frequência (43%) nos clones resistentes aos antibióticos. Tal incidência pode ser reflexo do método utilizado para selecção dos clones, o qual poderá estar a favorecer a selecção de clones com estas características. Apesar desta hipótese não estar ainda esclarecida, e portanto, desconhecermos se a selecção dependente da frequência tem uma baixa ou elevada incidência nas populações bacterianas resistentes, este estudo vem reforçar que a simples redução ou mesmo eliminação do uso de antibióticos não é uma medida eficaz no combate às resistências aos antibióticos. A ocorrência de selecção dependente da frequência em bactérias resistentes irá possibilitar a sua manutenção nas populações bacterianas, mesmo em baixas frequências. Assim que se reintroduzir novamente o antibiótico a resistência irá emergir em larga escala (De Gelder, et al., 2004). A selecção dependente da frequência deve ser um mecanismo considerado no estudo das dinâmicas das populações bacterianas e, em particular, nas populações resistentes aos antibióticos. Deste modo, torna-se necessário o desenvolvimento de novas terapêuticas alternativas aos antibióticos no combate às infecções bacterianas. Tal necessidade está na base do recente desenvolvimento de terapêuticas profiláticas, tais como a interferência bacteriana, vacinas bacterianas e a terapia fágica

Protein-carbohydrate recognition in the biodegradation of the plant cell wall: Functional and structural studies using carbohydrate microarrays and X-ray crystallography

The plant cell wall is, in its majority, constituted by complex and structurally diverse polysaccharides that are valuable resources for industrial and biotechnological applications. Anaerobic microbial organisms are highly efficient for plant cell wall polysaccharide biodegradation and have evolved a multi-enzyme complex system, the Cellulosome, where catalytic enzymes have non-catalytic Carbohydrate Binding Modules (CBMs) appended that highly potentiate the enzymes’ catalytic efficiency. Deciphering at molecular level the mechanisms underlying plant cell wall carbohydrate recognition and deconstruction by different cellulolytic bacteria is crucial to elucidate these complex biological systems, as well as to further promote novel potential applications. The work developed in this Thesis focused on the unique approach of combining carbohydrate microarrays with X-ray crystallography, to uncover carbohydrate ligands for CBMs and to structurally characterize novel CBM-carbohydrate interactions of two anaerobic bacteria that reside in different ecological niches: Clostridium thermocellum, found in soils, and Ruminococcus flavefaciens FD-1, present in the rumen of herbivorous. To this end, microarrays featuring carbohydrate probes with polysaccharide and oligosaccharide sequences representative of the structural diversity found on plant cell walls, but also in fungal and bacterial cell walls, were developed and then used to screen the carbohydrate-binding and ligand-specificity of 150 CBMs of C. thermocellum and R. flavefaciens CBMomes. The groups of polysaccharides that are differentially recognised were revealed for 59 CBMs and novel CBM-ligand specificities were identified for 23 modules from C. thermocellum and 21 from R. flavefaciens. Overall, the two bacteria differentially expressed CBM families with different carbohydrate-binding specificities, which may reflect adaptation to substrate availability in their specific ecological niche or the complexity of their Cellulosome. Using the information derived from the high-throughput microarray analysis, and according to their biotechnological relevance or novelty, CBMs and the respective ligands were selected for further structural studies. The novel CBM structures solved, complemented with biochemical and biophysical data, enabled the characterization of the molecular determinants for the recognition of mixed-linked β1,3-1,4-glucans by C. thermocellum family 11 CBM, chitin and peptidoglycan-derived sequences by a novel LysM domain from C. thermocellum family 50 CBMs, and pectic arabinans by R. flavefaciens family 13 CBM. The results reported here allow to assign a functional role for these CBMs and CBM families and contribute to the classification of the novel CBMs identified in the genome of the two bacteria, particularly those from R. flavefaciens FD1. Furthermore, the information derived from this integrative study, can promote a better understanding of cellulolytic capabilities of these bacteria, as well as to potentiate biotechnological applications of CBMs

Measuring the differences in productivities of Nations : a stochastic frontier approach

It is broadly accepted that differences in efficiency and productivity growth greatly contribute to the enormous differences in income across countries. Inefficiency levels were estimated for a panel of 40 countries, 34 of which are OECD-members and the remaining 6 are emergent economies, for the period of 2001-2011, using a stochastic frontier model based on the Battese and Coelli (1995) time-varying inefficiency model. Environmental variables were found to have an important role in explaining differences in technical efficiencies across countries. In particular, a high contribution of the agricultural sector and of natural resources rents to the economy, impediments to free trade such as tariffs, a bad business environment, a high number of patents, a high level of government debt and the financial crisis contribute negatively to technical efficiency. On the other hand, a good health status and good institutions help countries to be located closer to the frontier. Afterwards, productivity growth was decomposed using the Kumbhakar and Lovell (2000) primal frontier approach. The results showed that differences in TFP growth between developed and developing countries are the main drivers of the differences in the growth rates of GDP per worker, although differences in the factor accumulation also play an important role. Over the 2001-2011, we observed a general improvement in the technical efficiency of countries, which was outweighed by a downward shift in the stochastic production frontier

Using gold nanoparticles in protein crystallography: studies in crystal growth and derivatization

Dissertation for the Master Degree in Structural and Functional BiochemistryIn the field of protein structural analysis, X-ray crystallography plays a major role to expand the knowledge on how proteins function, as well as their interactions with other molecules. However, several obstacles can be present when attempting to grow protein crystals and subsequently determine its structure. Therefore, strategies that facilitate the production of suitable crystals for X-ray diffraction techniques, such as nucleating agents, or that allow overcoming the phase problem, as the production of heavy atom derivatives, are highly sought for. Additionally, coupling gold nanoparticles (AuNPs) with proteins is of emerging interest and a field that has been growing in recent years, for the development of bionanosystems that benefit of the advantages presented by AuNPs. Understanding these processes at the atomic level, would facilitate the study of the interactions between proteins and AuNPs, and allow a deeper insight into these bionanosystems for their development and optimization. The number of studies reported in the literature combining protein crystallography and AuNPs is, up to date, very limited. The work developed in this Dissertation aimed to study the crystallization of proteins in the presence of AuNPs, associated to the study of its structural interactions with the AuNPs and gold atoms, and also to investigate the hypothesis of producing gold derivatives of protein crystals using AuNPs. To accomplish this, crystallization studies of HEWL (hen egg-white lysozyme) were carried out in the presence of gold nanoparticles capped with Polyvinylpyrrolidone (AuNP-PVP) and in the presence of a Au(I) compound. X-ray diffraction data from the resultant crystals were then measured at one of the X-ray absorption edges of gold, in order to take advantage of the gold‟s scattering properties. HEWL structures were then determined exhibiting several binding sites for gold atoms at the protein‟s surface that were unambiguously identified by recurring to an electron density map calculated from the anomalous differences of the measured intensities. In addition, TEM analyses were carried out to verify the assembly and formation of the AuNPs within HEWL crystals. Zeta-potential and optic spectroscopic measurements were also used to study the AuNP-PVP stability alone and in solution with HEWL. The potential of gold nanoparticles-induced crystal growth was also explored by using differently functionalised AuNPs as nucleant agents in co-crystallization studies with several proteins. Quite positive results were obtained with the test proteins, HEWL and RNase A (ribonuclease A), and a slight improvement of human phenylalanine hydroxylase (PAH) crystallization was also observed

Ethical Standards for Information Systems Professionals - 30 years after “A Case for a Unified Code”

Technological advances increasingly mark our society, but also bring with them unique ethical challenges. In 1992, a paper entitled “Ethical Standards for Information Systems Professionals: A Case for a Unified Code” by Effy Oz was published in MISQ. Since then, much has happened in the area of technologies and information systems. New business contexts, methodological approaches, technologies, applications, and many other changes have occurred, requiring a renewed attention to ethical concerns and warranting a revisiting of the theme 30 years later. This article follows the same structure and methodological approach as used in Effy Oz’s work, focusing on the current versions of the ethical codes of leading organizations. The objectives are as follows: (1) to reflect on the changes made to the codes over 30 years, (2) to examine whether the recommendations proposed in Oz’s original work are reflected in the current versions of the codes, and (3) to conclude if the need for a unified code of ethics still prevails. The results indicate that, depending on the organization, the impact of the “passage of time” on the codes was different; several recommendations — which are still valid — are not fully reflected in the documents, thus continuing the need for a unified code of ethics (albeit with some different characteristics from those identified three decades ago)