On the kernel of a singular integral operator with non-carleman shift and conjugation

On the Hilbert space (L) over tilde (2)(T) the singular integral operator with non-Carleman shift and conjugation K = P+ +(aI + AC)P- is considered, where P-+/- are the Cauchy projectors, A = (m)Sigma(j=0) a(j)U(j), a, a(j), j = (1, m) over bar, are continuous functions on the unit circle T, U is the shift operator and C is the operator of complex conjugation. Some estimates for the dimension of the kernel of the operator K are obtained.Fundacao para a Ciencia e Tecnologia (Portugal) through Centro de Analise Funcional e Aplicacoes of Instituto Superior Tecnicoinfo:eu-repo/semantics/publishedVersio

Dynamic and interactive tools to support teaching and learning

The use of technological learning tools has been increasingly recognized as a useful tool to promote students’ motivation to deal with, and understand, mathematics concepts. Current digital technology allows students to work interactively with a large number and variety of graphics, complementing the theoretical results and often used paper and pencil calculations. The computer algebra system Mathematica is a very powerful software that allows the implementation of many interactive visual applications. The main goal of this work is to show how some new dynamic and interactive tools, created with Mathematica and available in the Computable Document Format (CDF), can be used as active learning tools to promote better student activity and engagement in the learning process. The CDF format allows anyone with a computer to use them, at no cost, even without an active Wolfram Mathematica license. Besides that, the presented tools are very intuitive to use which makes it suitable for less experienced users. Some tools applicable to several mathematics concepts taught in higher education will be presented. This kind of tools can be used either in a remote or classroom learning environment. The corresponding CDF files are made available as supplement of the online edition of this article.info:eu-repo/semantics/publishedVersio

Symbolic computation applied to the study of the kernel of special classes of paired singular integral operators

Operator theory has many applications in several main scientific research areas (structural mechan-ics, aeronautics, quantum mechanics, ecology, probability theory, electrical engineering, among others) and theimportance of its study is globally acknowledged. On the study of the operator’s kernel some progress has beenachieved for some specific classes of singular integral operators whose properties allow the use of particular strate-gies. However, the existing algorithms allow, in general, to study the dimension of the kernel of some classes ofsingular integral operators but are not designed to be implemented on a computer. The main goal of this paper is toshow how the symbolic and numeric capabilities of a computer algebra system can be used to study the kernel ofspecial classes of paired singular integral operators with essentially bounded coefficients defined on the unit circle.It is described how some factorization algorithms can be used to compute the dimension of the kernel of specialclasses of singular integral operators. The analytical algorithms [ADimKerPaired-Scalar], [AKerPaired-Scalar],and [ADimKerPaired-Matrix] are presented. The design of these new algorithms was focused on the possibility ofimplementing on a computer all the extensive symbolic and numeric calculations present in the algorithms. Forthe essentially bounded hermitian coefficients case, there exist some relations with Hankel operators. The papercontains some interesting and nontrivial examples obtained with the use of a computer algebra system.Fundação para a Ciência e Tecnologia (Portugal) through the Center for Functional Analysis, Linear Structures and Applicationsinfo:eu-repo/semantics/publishedVersio

Stomach cancer incidence in Southern Portugal 1998-2006:a spatio-temporal analysis

Understanding geographical differences in health, particularly in small areas, became a major concern of epidemiologists. Geographical association studies and, more recently, several spatial disease mapping studies have emerged due to the development of new spatial statistical tools. Among other diseases, these methods are being applied to analyze cancer data. However, in this kind of studies, it is of utmost importance to also investigate the influence of temporal variability and that is why spatio-temporal studies became so popular. The aim of this study is to investigate spatial and temporal trends for the incidence of this type of cancer. This retrospective population-based study is based on data on all stomach cancers registered by the Southern Portuguese Cancer Registry (ROR Sul) between 1998 and 2006. Because several studies have underlined the important role of socioeconomic status in cancer risk, information on this variable has also been taken into account. Bayesian hierarchical models were applied to model stomach incidence at a county level and resulting relative risks were used to build risk maps for cancer incidence. Age-Period-Cohort models were also applied.N/

Utilização de lisinas de bacteriófagos no controlo de bactérias patogénicas gram-positivas

Tese de mestrado, Biologia (Microbiologia Aplicada), 2009, Universidade de Lisboa, Faculdade de CiênciasAs endolisinas ou, simplesmente, lisinas são hidrolases da parede celular bacteriana, sintetizadas na fase final do ciclo lítico de fagos de DNA de cadeia dupla, cuja acção permite a libertação da progenia viral. Diversos estudos recentes demonstraram que as lisinas quando aplicadas exogenamente a bactérias Gram-positivas, como proteínas recombinantes purificadas, têm a capacidade de degradar o peptidoglicano da parede celular, causando a lise rápida da célula bacteriana. Com este trabalho pretendeu-se inicialmente caracterizar, clonar e expressar lisinas activas contra Staphylococcus aureus e Propionibacterium acnes. Para aumentar a solubilidade destas enzimas produziram-se proteínas truncadas, contendo apenas o domínio catalítico e, lisinas quiméricas em que se conjugaram diferentes domínios catalíticos e motivos de ligação à parede celular de origem heteróloga. As lisinas que demonstraram melhor solubilidade e actividade lítica foram purificadas por cromatografia de afinidade. Estas foram uma lisina truncada (Lys161) contendo apenas o domínio de endopeptidase CHAP da lisina Lys87, especifica para S. aureus, e duas lisinas quiméricas (Lys168- 87 e Lys170-87) contendo, respectivamente, os domínios catalíticos endopeptidase CHAP e de Amidase-2 de lisinas de Enterococcus sp., fundidos ao domínio C-terminal de Lys87 que apresenta os motivos de ligação ao peptidoglicano. A avaliação da actividade lítica das lisinas em isolados bacterianos de meios hospitalares e da comunidade evidenciou um elevado potencial lítico das lisinas quiméricas em mais de 90% das estirpes de S. aureus testadas, incluindo uma elevada fracção destas com resistência à meticilina. Estas quimeras demonstraram também capacidade de lise em estirpes de Enterococcus spp., Staphylococcus epidermidis, Staphylococcus haemolyticus, Staphylococcus saprophyticus, Streptococcus pyogenes, Micrococcus luteus e Bacillus spp. A lisina truncada Lys161, comparativamente, apresentou menor actividade lítica, com redução do espectro lítico. Os resultados obtidos demonstram o potencial das lisinas quiméricas produzidas na eliminação de bactérias patogénicas, incluindo estirpes de S. aureus resistentes à meticilina.Endolysins, or simply lysins, are bacterial cell wall hydrolysing enzymes that are produced at the end of the lytic cycle of double stranded DNA phages, to allow the release of viral progeny. Many recent studies have shown that when applied externally to Gram-positive bacteria, as purified recombinant proteins, lysins are capable of degrading the cell wall peptidoglycan, resulting in a rapid bacterial cell lyses. This study initially aimed the characterization, cloning and expression of lysins targeting Staphylococcus aureus and Propionibacterium acnes. To increase their solubility the enzymes were produced in the form of truncated proteins, which exclusively carried the catalytic domain, and chimerical polypeptides where different catalytic and cell wall binding domains of heterologous origin were fused. The lysins that exhibited higher solubility and lytic activity were purified by affinity chromatography. Specifically, these were a truncated derivative of Lys87 (Lys161), containing only a CHAP peptidase domain acting on S. aureus, and two chimerical lysins (Lys168-87 and Lys170-87) comprising, respectively, the functional CHAP peptidase and amidase-2 domains of Enterococcus sp. lysins fused to the cell wall targeting domain of the S. aureus lysin Lys87. The evaluation of lysin bacteriolytic activity on bacterial clinical isolates from hospital and community samples showed a high lytic potential of chimerical lysins, which were able to lyse more than 90% of the tested S. aureus strains, including a high fraction of methicillin-resistant isolates. These chimeras also displayed lytic activity against strains of Enterococcus spp., Staphylococcus epidermidis, Staphylococcus haemolyticus, Staphylococcus saprophyticus, Streptococcus pyogenes, Micrococcus luteus and Bacillus spp. Truncated lysin Lys161 showed less lytic activity and a narrow spectrum when compared to the chimerical endolysins. Our results demonstrate the potential of chimerical lysins to eliminate pathogenic bacteria, including methicillin-resistant S. aureus strains

Owl ontology quality assessment and optimization in the cybersecurity domain

The purpose of this dissertation is to assess the quality of ontologies in patterns perceived by cybersecurity context. A content analysis between ontologies indicated that there were more pronounced differences in OWL ontologies in the cybersecurity field. Results showed an increase of relevance from expressivity to variability. Additionally, no differences were found in strategies used in most of the incidents. The ontology background needs to be emphasized to understand the quality of the phenomena. In addition, ontologies are a means of representing an area of knowledge through their semantic structure. The search of information and integration of data from different origins provides a common base that guarantees the coherence of the data. This can be categorized and described in a normative way. The unification of information with the world that surrounds us allows to create synergies between entities and relationships. However, the area of cybersecurity is one of the real-world domains where knowledge is uncertain. It is therefore necessary to analyze the challenges of choosing the appropriate representation of un-structured information. Vulnerabilities are identified, but incident response is not an automatic mechanism for understanding and processing unstructured text found on the web.O objetivo desta dissertação foi avaliar a qualidade das ontologias, em padrões percebidos pelo contexto de cibersegurança. Uma análise de conteúdo entre ontologias indicou que havia diferenças mais pronunciadas por ontologias OWL no campo da cibersegurança. Os resultados mostram um aumento da relevância de expressividade para a variabilidade. Além disso, não foram encontradas diferenças em estratégias utilizadas na maioria dos incidentes. O conhecimento das ontologias precisa de ser enfatizado para se entender os fenómenos de qualidade. Além disso, as ontologias são um meio de representar uma área de conhecimento através da sua estrutura semântica e facilita a pesquisa de informações e a integração de dados de diferentes origens, pois fornecem uma base comum que garante a coerência dos dados, categorizados e descritos, de forma normativa. A unificação da informação com o mundo que nos rodeia permite criar sinergias entre entidades e relacionamentos. No entanto, a área de cibersegurança é um dos domínios do mundo real em que o conhecimento é incerto e é fundamental analisar os desafios de escolher a representação apropriada de informações não estruturadas. As vulnerabilidades são identificadas, mas a resposta a incidentes não é um mecanismo automático para se entender e processar textos não estruturados encontrados na web

Integrating the theme approach with aspectual scenarios

Dissertação de Mestrado em Engenharia InformáticaAspect-oriented requirements engineering emerged to deal with crosscutting requirements, i.e. requirements that are scattered in the requirements document and tangled with other requirements. There are several aspect-oriented requirements approaches - Theme, proposed by Baniassad and Clarke [7], is one of them. This approach is characterized by the identification of a set of actions associated to verbs present in requirements documentation. These actions are then analyzed in order to identify crosscutting behaviours, each one constituting a potential theme. One problem with this approach is that the composition mechanism is not expressive enough even when the Theme models are integrated to analysis models (e.g. UML diagrams). The MATA approach [24] provides powerful composition mechanisms, based on graph transformations that used UML models, in particular behaviour models (e.g. sequence or activity like diagrams). These models express scenarios that constitute a very popular and used technique to specify a system’s behaviour. Therefore, the result of the integration of these two approaches will be synergetic. Also, considering that in a system not only the expected situations happen, scenarios can also be used to illustrate unexpected situations, making their treatment possible. Negative scenarios are thus also considered, besides the positive ones: their representation is similar, only differing from an optimist and mostly assumed vision of the system’s behavior. These scenarios could be identified with Theme and mapped into MATA. In summary, the objective of this dissertation is twofold: firstly, we will integrate Theme with Aspectual Scenarios (specified in MATA); secondly, we will extend Theme to include the modeling of negative scenarios. The result will be the synergy between two complementary techniques, including the specification of undesirable situations, where behavioral and structural aspect modeling are integrated

Wolfram | Alpha: uma ferramenta de aprendizagem ativa em Cálculo I

O motor de conhecimento computacional Wolfram|Alpha, desenvolvido pela Wolfram Research, é uma ferramenta dinâmica e interativa, de acesso livre e manuseamento intuitivo, que explora tópicos de várias áreas do conhecimento. Estas características facilitam a sua utilização no ensino e propiciam a criação de um contexto de aprendizagem ativa em sala de aula. O Wolfram|Alpha foi utilizado, no ano letivo 2013/14, em aulas de Cálculo I, disciplina transversal a diversos cursos de ciências naturais na Universidade do Algarve, com o objetivo de consolidar conteúdos programáticos adquiridos durante o ensino secundário e de tornar mais interessante a aquisição de novos conceitos matemáticos nas áreas do Pré-Cálculo e do Cálculo Diferencial. Com o propósito de recolher e analisar as opiniões dos alunos sobre a importância da utilização do Wolfram|Alpha como instrumento de aprendizagem em Cálculo I foi elaborado um questionário e recolhidas as opiniões dos alunos matriculados na respectiva unidade curricular e que se submeteram à avaliação.info:eu-repo/semantics/publishedVersio

Efeitos bioquímicos de extractos de alfazema (Lavandula sp.) no crescimento de Chlorella vulgaris

Os sistemas aquáticos podem apresentar um desenvolvimento excessivo de fitoplâncton e de algas filamentosas devido à eutrofização. Para mitigar os problemas ambientais e económicos daí resultantes, tem-se procedido à aplicação de químicos, com o inconveniente da serem persistentes e potencialmente tóxicos, bem como de eficácia discutível. O laboratório de Produção de Fitoplâncton da Escola Agrária de Bragança tem vindo a desenvolver estudos sobre a utilização de plantas e dos seus extractos como algicidas/algistáticos naturais. Os resultados obtidos sugerem que os óleos essenciais testados apresentam um efeito algicida forte para duas espécies de microalgas. O efeito algicida dos óleos essenciais de alfazema no crescimento da ChlorelJa vulgaris CBSC 15-2075 foi avaliado na actividade das fosfatases. As culturas de C. vulgaris em fase exponencial foram expostas a óleos essenciais de alfazema na proporção de 1:120 (1 ml de óleos essenciais num total de 120 ml de cultura}. Os ensaios decorreram durante 6 dias em câmaras de cultura à temperatura de 22 °C, intensidade luminosa de 2390 lx com um fotoperíodo de 16 h/8 h luz/escuro, sendo agitados manualmente uma vez por dia. Os parâmetros determinados incluíram: taxa específica de crescimento (1-J}, tempo de duplicação (td}, pigmentos fotossintéticos, proteínas totais e atividade da fosfatase ácida e alcalina. Com este trabalho espera-se contribuir para uma melhor compreensão dos mecanismos de ação tóxica desencadeados pelos óleos essenciais sobre as microalgas