Interactions of phosphoinositide specific phospholipase C with a lipid layer for structural and functional studies

Phosphoinositide-specific phospholipase C (PLC) is an intensively studied family of enzymes constituting a junction between trans-membrane signal transduction processes and phosphoinositide lipid signalling. PLCs are activated in response to stimulation of cell surface receptors at the plasma membrane, and the signals are carried downstream by other transducers. PLCs catalyse the hydrolysis of phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] to diacylglycerol and inositol 1,4,5-trisphosphate, which are both well known intracellular second messengers. This study mainly focused on the PLCε sub-family which is closely linked to the Ras oncogene and may play a role in tumorigenesis and development. The functions and regulatory mechanism of PLCε are not yet understood in detail. To address these issues activity and structural studies were performed. Activity studies were carried out in vivo using cell lines and in vitro using lipid vesicles in a model system. The latter was designed to study protein-protein and lipid-protein interactions using PLC purified to homogeneity and guanosine triphosphatases (GTPases) prenylated in vitro. Evidence was found for a direct interaction between the GTPases and the PLC that mediated activation of the phospholipase. Furthermore, the correlation between PLC activity and substrate presentation in lipid vesicles of various sizes and lipid compositions was analysed. For the first time, PLC activity was found to depend upon the electrostatic potential and the stored elastic curvature stress of the lipid bilayer of the vesicles. The binding and the activation process between GTPase (using H-Ras) and PLCε was also investigated at a molecular level in vitro. Functional studies were carried out using Förster resonance energy transfer (FRET) to determine if PLCε undergoes a conformational change upon H-Ras binding. This would distinguish whether conformational change or translocation of PLCε to the membrane interface (where GTPases are localised) is most likely to be the key event during PLCε activation; no conformational change was observed. Electron crystallographic structural studies, in which two-dimensional protein crystals are grown on a lipid monolayer followed by electron microscopy, were attempted. The aim was to retrieve structural information in a functional state that resembles the natural one. Protein and lipid monolayer compositions (lipid proportions, lipid concentration, protein concentration and incubation time) were screened to identify conditions where specific protein-lipid interaction would favour twodimensional crystal formation. The protein was expressed with a His6-tag that allowed specific binding to nickel chelating lipids included in the lipid monolayer. In addition, catalytically inactive PLCε mutants were generated and their ability to bind PtdIns(4,5)P2, and thereby to drive the crystallisation process, was investigated. Conditions that led to protein-lipid binding, but not to two-dimensional crystallisation, were identified

Workarounds as Means to Identify Insider Threats to Information Systems Security

Workarounds represent deliberate actions of employees in contrast with the prescribed practices and organizations generally perceive them as unwanted processes. Workarounds may lead to information systems (IS) security policy violations, notably when prescribed practices lead employees to face obstacles in accomplishing their daily tasks. Such behavior generates new insider threats to IS security. In this article, we adopt the view that workarounds may enable the identification of new security threats. We propose a conceptual model that illustrates how workarounds generating non-malicious security violations might constitute sources of knowledge about new security threats

A variação dos pronomes possessivos de segunda pessoa do singular teu/seu na Região Sul do Brasil

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Comunicação e Expressão. Programa de Pós-Graduação em Linguística.Nesta dissertação, analisamos a variação dos pronomes possessivos de segunda pessoa do singular teu/seu, nas cidades de Blumenau, hapecó, Flores da Cunha, Florianópolis, Lages, Panambi, Porto Alegre e São Borja. Consideramos tanto os aspectos lingüísticos quanto os aspectos sociais dessa variação, à luz dos pressupostos teóricos da sociolingüística riacionista (WEINREICH, LABOV e HERZOG, 1968; LABOV, 1972) e da proposta de Brown e Gilman (2003) The Pronouns of Power and Solidarity. Os dados foram coletados de 192 entrevistas pertencentes ao banco de dados VARSUL (Variação Lingüística Urbana da Região Sul do Brasil), as quais são estratificadas de acordo com as variáveis faixa etária, sexo, escolaridade e região (etnia). Para a análise dos dados, utilizamos o programa VARBRUL. Os resultados para a variação dos possessivos de segunda pessoa do singular apontam para algumas direções. Há uma relação entre os pronomes pessoais tu e você e os pronomes possessivos teu e seu, uma vez que o primeiro grupo selecionado significativo foi o paralelismo formal. Quanto aos fatores sociais, as mulheres tendem a utilizar mais o possessivo teu (há indícios, portanto, de que este possessivo tenha prestígio, naquelas regiões, embora o possessivo seu seja isento de estigma). Outro grupo selecionado significativo é a escolaridade, com maior tendência ao uso do possessivo teu pelos informantes de nível ginasial. As questões de poder e solidariedade entre os interlocutores também estão em jogo na variação destes possessivos. Os resultados mostram, por exemplo, que o pronome teu é mais usado nas relações simétricas ou nas assimétricas de superior para inferior, enquanto seu é mais usado nas relações de inferior para superior. Além disso, os mais jovens tendem a utilizar o possessivo teu, ou seja, tendem a utilizar mais a forma solidária, o que corrobora a hipótese de Brown e Gilman (2003) sobre as alterações que vêm ocorrendo nas sociedades modernas

Classification of Decision Support Systems for Cybersecurity

As part of a research and development program aimed at providing a decision support system for cyber risk management, we conducted an in-depth analysis of the research, innovation and collaboration environment for decision support technologies and mathematical decision support systems for cybersecurity. We analysed 5,841 documents from three different databases and derived 79 significant decision support systems. We conducted a bibliometric and semantic analysis of all documents to identify the dynamics of collaboration, research trends, and other structural elements, and we analysed these 79 models under 16 risk management evaluation criteria to assess their relevance. This work now allows for a better understanding of the dynamics underlying cyber risk modelling research, an analysis of the models used by academic and private research, a classification of these models regarding these same evaluation criteria, and a taxonomy of decision support systems for cybersecurity

Classification of Decision Support Systems for Cybersecurity

As part of a research and development program aimed at providing a decision support system for cyber risk management, we conducted an in-depth analysis of the research, innovation and collaboration environment for decision support technologies and mathematical decision support systems for cybersecurity. We analysed 5,841 documents from three different databases and derived 79 significant decision support systems. We conducted a bibliometric and semantic analysis of all documents to identify the dynamics of collaboration, research trends, and other structural elements, and we analysed these 79 models under 16 risk management evaluation criteria to assess their relevance. This work now allows for a better understanding of the dynamics underlying cyber risk modelling research, an analysis of the models used by academic and private research, a classification of these models regarding these same evaluation criteria, and a taxonomy of decision support systems for cybersecurity

Análise de correspondência aplicada à pesquisa de desigualdade na educação brasileira

Há uma profunda desigualdade social no Brasil. Claramente o modelo desenvolvimento proposto até aqui fez pouco para equilibrar as oportunidades entre a camada social mais abastada e a camada social mais vulnverável. Analisando as diferentes etnias do país, observa-se que a população não branca enfrenta mais dificuldades em sua trajetória escolar e, posteriormente, em sua vida adulta. Políticas afirmativas têm sido implementadas para corrigir essas distorções, mas ainda estão longe de mitigar os efeitos negativos da situação atual. Além do desenvolvimento de ações para atenuar as desigualdades no país, mostra-se fundamental avaliar e implementar medidas efetivas no combate da desigualdade. Nesse sentido, uso da estatística é importante para o processamento e a análise de dados. Técnicas de Estatística Multivariada estão sendo amplamente utilizadas para realizar análise exploratórias dos dados, ajudando pesquisadores na formulação de hipóteses das causas de problemas enfretandos por nossa sociedade. A trajetória escolar dos estudantes brasileiros na Educação Básica é divergente a depender da sua etnia. Portanto, identificar quais fatores econômicos e culturais se diferenciam entre alunos pode auxiliar na formulação e implementação de ações públicas. Análise de Correspondência é um método estatístico para dados categóricos que, através da redução de dimensionalidade, apresenta graficamente as relações entre variáveis e categórias de uma matriz de dados. Usando dados públicos do Exame Nacional do Ensino Médio, esse trabalho de conclusão de curso estudou a relação entre as etnias e variáveis socioeconômicas de estudantes brasileiros.There is deep social inequality in Brazil. Clearly, the proposed model has been little developed so far to balance the opportunities between a more affluent and a more vulnerable social strata. Analyzing the different ethnicities in the country, it is observed that the non-white population faces more difficulties in their school trajectory and, later, in their adult life. Affirmative policies have been avoided to correct these distortions, but policies are being corrected based on the current situation. In addition to developing actions to mitigate inequalities in the country, it is essential to evaluate and implement effective measures to combat inequality. In this sense, the use of statistics is important for data processing and analysis. Multivariate Statistical Techniques are being widely used to carry out problem analysis in researching hypotheses about the causes of our society. The school trajectory of Brazilian students in Basic Education is different depending on their ethnicity. Therefore, what are the differentiating and cultural factors among the students that can help in the formulation and implementation. Correspondence Analysis is a statistical method for categoricals that, through dimensionality data reduction, graphically presents the variables between variables and categoricals of a data matrix. Public data from the National High School Exam, this course conclusion work studied the relationship between ethnicities and socioeconomic variables of Brazilian students

Comparison of aerodynamic models for Vertical Axis Wind Turbines

Multi-megawatt Vertical Axis Wind Turbines (VAWTs) are experiencing an increased interest for floating offshore applications. However, VAWT development is hindered by the lack of fast, accurate and validated simulation models. This work compares six different numerical models for VAWTS: a multiple streamtube model, a double-multiple streamtube model, the actuator cylinder model, a 2D potential flow panel model, a 3D unsteady lifting line model, and a 2D conformal mapping unsteady vortex model. The comparison covers rotor configurations with two NACA0015 blades, for several tip speed ratios, rotor solidity and fixed pitch angle, included heavily loaded rotors, in inviscid flow. The results show that the streamtube models are inaccurate, and that correct predictions of rotor power and rotor thrust are an effect of error cancellation which only occurs at specific configurations. The other four models, which explicitly model the wake as a system of vorticity, show mostly differences due to the instantaneous or time averaged formulation of the loading and flow, for which further research is needed.Aerodynamics, Wind Energy & PropulsionAerospace Engineerin