Simulated emergence of cyclic sexual-asexual reproduction

Motivated by the cyclic pattern of reproductive regimes observed in some species of green flies (``{\it aphids}''), we simulate the evolution of a population enduring harsh seasonal conditions for survival. The reproductive regime of each female is also seasonal in principle and genetically acquired, and can mutate for each newborn with some small probability. The results show a sharp transition at a critical value of the survival probability in the winter, between a reproductive regime in the fall that is predominantly sexual, for low values of this probability, or asexual, for high values.Comment: 9 pages, 4 figures, requires RevTe

Fragmentation Experiment and Model for Falling Mercury Drops

The experiment consists of counting and measuring the size of the many fragments observed after the fall of a mercury drop on the floor. The size distribution follows a power-law for large enough fragments. We address the question of a possible crossover to a second, different power-law for small enough fragments. Two series of experiments were performed. The first uses a traditional film photographic camera, and the picture is later treated on a computer in order to count the fragments and classify them according to their sizes. The second uses a modern digital camera. The first approach has the advantage of a better resolution for small fragment sizes. The second, although with a poorer size resolution, is more reliable concerning the counting of all fragments up to its resolution limit. Both together clearly indicate the real existence of the quoted crossover. The model treats the system microscopically during the tiny time interval when the initial drop collides with the floor. The drop is modelled by a connected cluster of Ising spins pointing up (mercury) surrounded by Ising spins pointing down (air). The Ising coupling which tends to keep the spins segregated represents the surface tension. Initially the cluster carries an extra energy equally shared among all its spins, corresponding to the coherent kinetic energy due to the fall. Each spin which touches the floor loses its extra energy transformed into a thermal, incoherent energy represented by a temperature used then to follow the dynamics through Monte Carlo simulations. Whenever a small piece becomes disconnected from the big cluster, it is considered a fragment, and counted. The results also indicate the existence of the quoted crossover in the fragment-size distribution.Comment: 6 pages, 3 figure

Electrochemical oxidation of abietanes

Trabalho Final de Mestrado Integrado, Ciências Farmacêuticas, 2021, Universidade de Lisboa, Faculdade de Farmácia.Os pinheiros são coníferos, dos quais se pode adquirir a madeira e extrair o “tall oil” bruto, a resina e a goma da madeira. Através da destilação da resina podemos adquirir a colofónia e terebintina. A colofónia consiste numa mistura complexa de terpenos neutros e diterpenos ácidos, onde se incluem os abietanos, que são diterpenoides tricíclicos aos quais o ácido abiético (AA) e dehidroabiético (DHA) pertencem. A eletroquímica combina a transferência de eletrões no elétrodo com uma reação química, sendo que podem ser controladas utilizando corrente ou potencial constante. Acabam por ser reações “mais verdes”, seguras, eficientes e económicas. A eletrólise pode ser direta, onde se oxida/reduz diretamente a molécula, ou indireta, onde um se utiliza mediadores, reagentes capazes de oxidar/reduzir seletivamente a molécula. A eletroquímica em fluxo é uma técnica que permite o scale up industrial da eletroquímica, tendo vantagens sobre esta como o oferecer uma maior proximidade entre elétrodos e uma maior área de superfície do elétrodo, o que diminui o tempo de reação e permite a dispensa do uso de eletrólitos de suporte. Neste contexto, o principal objetivo desta investigação assentou em acrescentar valor biossintético à colofónia e aos seus abietanos, utilizando reações orgânicas clássicas, eletroquímica e química em fluxo para sintetizar novos derivados e estudar os potenciais de oxidação destes compostos. Relativamente ao trabalho experimental, começou se por preparar os derivados metil éster do AA e do DHA, pois seriam compostos mais estáveis. Estudamos os potenciais de oxidação destes compostos. Desenvolvemos e otimizamos protocolos para a oxidação eletroquímica, onde conseguimos alcançar a oxidação benzílica direta tanto do DHA como do MDHA com bons rendimentos, a oxidação indireta do MDHA (utilizando Cl4NHPI como mediador) e também conseguimos alcançar a oxidação de AA e MAA com rendimentos moderados. Por fim estudou-se o uso de eletroquímica em fluxo para realizar estas oxidações, usando-se o DHA como material de partida.Pine trees are coniferous, from which we can extract wood, raw tall oil, wood gum, and gum. Through the distillation of gum, we can acquire turpentine and colophony. Colophony is a complex mixture of neutral terpenes and acidic diterpenes, including abietanes, which are tricyclic diterpenoids to which abietic acid (AA) and dehydroabietic acid (DHA) both belong. Electrochemical reactions combine the electron transfer at an electrode with a chemical reaction and can be controlled using constant current or constant potential. Overall, they are very environmentally friendly, safer, efficient, and economical. The electrolysis process can be direct, where we are able to directly oxidize/reduce the molecule, or indirect, where we use a mediator – a selective oxidizing/reducing reagent. Flow electrochemistry is a technique that allows the industrial scale up of electrochemistry, having advantages over it such as offering greater proximity between electrodes and a higher surface area of the electrode, which decreases the reaction time and allows the dispensation of the use of supporting electrolytes. In this regard, the main objective of this research was to add biosynthetic value to colophony and its abietanes, using classic organic reactions and electrochemistry to synthesize new derivates and then study the oxidation potentials of these compounds. Regarding the experimental work, we started by preparing the methyl ester derivatives of AA and DHA, as they would be more stable compounds. We studied the oxidation potentials of these compounds. We developed and optimized protocols for electrochemical oxidation, where we achieved the direct benzylic oxidation of both DHA and MDHA with good yields, the indirect oxidation of MDHA (using Cl4NHPI as a mediator) and we also achieved the oxidation of AA and MAA with moderate yields. Finally, we studied the use of flow electrochemistry to achieve these oxidations using DHA as starting material.Com o patrocínio do Plano de Desenvolvimento Rural 2014-2020 (PDR2020-101-032319 (Parceiro)) and Fundação para a Ciência e a Tecnologia (FCT) (UIDB/04138/2020 and UIDP/04138/2020) for financial support. The project leading to this application has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 951996)

Métodos etnográficos na detecção de oportunidades de inovação.

Tese de mestrado. Faculdade de Engenharia. Universidade do Porto. 201

Influence of moisture absorption on quasi-static and long-term failure of a GRP pipe under lateral compression

Tese de Mestrado. Mestrado em Engenharia Mecânica. Faculdade de Engenharia. Universidade do Porto. 200

Visualization of security in industrial control systems respecting IEC-62443

The importance of visualizing security in industrial control systems respecting the IEC62443 security standards has increased. This is due to the increase in cyber attacks, its complexity over time, and the security standards created to protect users from compromising them. Through an adequate visualization of security information, it is possible to manage and analyze information to make decisions for good management of systems' security. In this sense, this study's main objective was to describe a possible solution to assist in security management, having been developed in partnership with Siemens Technology, based in Germany. Thus, appropriate tools were used and evaluated to model the data and create visual elements to represent the industrial control system's components. Their security attributes were chosen to be in a dashboard. Kibana was used for three case studies, the last one being the most important for Siemens. The data were obtained through the security software test tool. These were organized and treated to be in a configuration that allowed them to be imported into Kibana and create a dashboard containing the information needed to make decisions and discover gaps in the system. Subsequently, the proposed solution was evaluated through a questionnaire applied to the specialists responsible for industrial control systems security to obtain suggestions that would improve its usefulness and security management assistance. From the results obtained, it was possible to observe the security representation using a visualization tool, demonstrate compliance with IEC-62443 security protocols, thus enabling a simplified security analysis of an industrial control system.A importância de visualizar segurança em sistemas de controlo industrial respeitando as normas de segurança IEC-62443 tem vindo a aumentar. Isto deve-se, ao aumento dos ciberataques, da sua complexidade e das normas criadas para proteger os sistemas. Através de uma adequada visualização de informação sobre a segurança torna-se possível gerir e analisar a informação para tomar decisões e fazer uma boa gestão de segurança. O presente estudo teve como principal objetivo descrever uma solução possível para auxiliar na gestão de segurança tendo sido desenvolvida em parceria com Siemens Technology, sediada na Alemanha. Assim, recorreu-se à avaliação das ferramentas utilizadas para modelar dados e criar elementos visuais para representar os componentes num sistema de controlo industrial e os atributos de segurança escolhidos para estarem num "dashboard". O "Kibana" foi utilizado para três casos, sendo o último o mais importante para a Siemens. Os dados foram obtidos através da ferramenta de teste do software de segurança. Estes foram organizados e tratados de forma a criar um "dashboard" contendo a informação necessária para tomar decisões e descobrir lacunas no sistema. Posteriormente, a solução proposta foi avaliada através de um questionário aplicado aos especialistas de segurança de sistemas de controlo industrial, com o propósito de se obterem sugestões que permitissem melhorar a sua utilidade e assistência na gestão da segurança. Com os resultados obtidos foi possível observar a representação de segurança utilizando uma ferramenta de visualização, respeitando os protocolos de segurança IEC-62443, possibilitando, uma análise simplificada da segurança num sistema de controlo industrial

Phase transition in a mean-field model for sympatric speciation

We introduce an analytical model for population dynamics with intra-specific competition, mutation and assortative mating as basic ingredients. The set of equations that describes the time evolution of population size in a mean-field approximation may be decoupled. We find a phase transition leading to sympatric speciation as a parameter that quantifies competition strength is varied. This transition, previously found in a computational model, occurs to be of first order.Comment: accepted for Physica

Study of in vivo interactions between penicillin-binding proteins of Staphylococcus aureus

Staphylococcus aureus (S. aureus) is a major human pathogen that has acquired resistance to practically all classes of β-lactam antibiotics, being responsible of Multidrug resistant S. aureus (MRSA) associated infections both in healthcare (HA-MRSA) and community settings (CA-MRSA). The emergence of laboratory strains with high-resistance (VRSA) to the last resort antibiotic, vancomycin, is a warning of what is to come in clinical strains. Penicillin binding proteins (PBPs) target β-lactams and are responsible for catalyzing the last steps of synthesis of the main component of cell wall, peptidoglycan. As in Escherichia coli, it is suggested that S. aureus uses a multi-protein complex that carries out cell wall synthesis. In the presence of β-lactams, PBP2A and PBP2 perform a joint action to build the cell wall and allow cell survival. Likewise, PBP2 cooperates with PBP4 in cell wall cross-linking. However, an actual interaction between PBP2 and PBP4 and the location of such interaction has not yet been determined. Therefore, investigation of the existence of a PBP2-PBP4 interaction and its location(s) in vivo is of great interest, as it should provide new insights into the function of the cell wall synthesis machinery in S. aureus. The aim of this work was to develop Split-GFPP7 system to determine interactions between PBP2 and PBP4. GFPP7 was split in a strategic site and fused to proteins of interest. When each GFPP7 fragment, fused to proteins, was expressed alone in staphylococcal cells, no fluorescence was detectable. When GFPP7 fragments fused to different peptidoglycan synthesis (PBP2 and PBP4) or cell division (FtsZ and EzrA) proteins were co-expressed together, fluorescent fusions were localized to the septum. However, further analysis revealed that this positive result is mediated by GFPP7 self-association. We then interpret the results in light of such event and provide insights into ways of improving this system

Hair styling industry : the responsiveness of portuguese male consumers : Studio Line case study

This dissertation provides an overview on relevant marketing-related subjects such as brand personality, positioning, consumer behaviour and communication through the analysis of a case study on Studio Line by L’Oréal Paris in Portugal, a Hair Styling brand targeted at the male market. The case study starts by presenting the Hair Styling market in both Europe and Portugal in particular, its evolution and the current barriers and opportunities. Then Studio Line is presented, its evolution, current strategy, positioning and place in the market, both in terms of sales and portfolio. The whole dissertation aims to answer a challenge the brand faces today: How can Studio Line, being the market leader, increase the penetration of Hair Styling in the Portuguese male market? This challenge arises from a constant negative trend of this segment in the Portuguese market, presenting a penetration rate that is half of the European average. Results of the analysis of the Portuguese male market are presented and its implications for Studio Line’s strategy are discussed. The dissertation finishes with a Teaching Note, where scholars can find the case study summarized and instructions on how to apply it in a classroom setting.A presente dissertação aborda temas relacionados com marketing relevantes, tais como personalidade da marca, posicionamento, comportamento do consumidor e comunicação, através da análise de um caso de estudo de Studio Line de L’Oréal Paris em Portugal, uma marca de Hair Styling direccionada ao mercado masculino. O caso de estudo começa por apresentar o mercado de Hair Styling, tanto na Europa como em Portugal, a sua evolução e as presentes barreiras e oportunidades. Depois, a marca Studio Line é apresentada, a sua evolução, estratégia e posicionamento actuais e a sua posição no mercado, tanto em valor como em termos de portfolio. A dissertação tem como objectivo responder a um desafio enfrentado pela marca nos dias de hoje: Como pode Studio Line, sendo líder de mercado, aumentar a penetração de Hair Styling no mercado masculino Português? Este dilema surge de uma tendência negativa constante deste segmento no mercado Português, levando a metade da taxa de penetração da média Europeia. Os resultados da análise do mercado masculino Português são apresentados e as suas implicações para a estratégia de Studio Line são discutidas. A dissertação termina com uma Nota de Ensino, em que académicos poderão encontrar o caso de estudo resumido e instruções em como aplicá-lo em sala de aula