Dispositivos em fibra óptica para lasers de alta potência

Mestrado em Engenharia FísicaO presente trabalho tem como objectivo o desenvolvimento de dispositivos em fibra óptica que possam ser utilizados em lasers de fibra de alta potência. É desenvolvido um laser pulsado de fibra monomodo dopada com Ytérbio (Yb3+) pelo método de Q-switching, que pode ser utilizado como fonte de bombeamento de sistemas laser pulsados de elevada potência. De seguida é demonstrado um adaptador de modo de uma fibra monomodo para uma fibra de núcleo largo, com baixas perdas de inserção e excelente qualidade do modo, para integração futura da fonte de bombeamento num sistema MOPA. Esta dissertação é composta por uma introdução teórica aos lasers de fibra de elevada potência, e ao método de Q-switching. A descrição e caracterização do laser Q-switched desenvolvido, e o processo de construção do modulador magnetostritivo utilizado são também apresentados. Por fim, é efectuada uma descrição do adaptador de modo fabricado, dando particular atenção ao processo de produção dos tapers em fibra, e posteriormente são apresentados e discutidos os resultados obtidos. ABSTRACT: The objective of the present work is the development of fiber optic components for applications in high power fiber lasers. A pulsed Yb3+ doped single mode fiber laser is developed by the Q-switching method, which could be used as a pump source in high power pulsed fiber laser systems. The development of a mode field adaptor from a single mode to large mode area fiber is also related. The low insertion losses and the excellent beam quality of this component allows the integration of the pump source in a MOPA system. The following thesis contains a theoretical introduction to high power fiber lasers and the Qswitching method. The description and characterization of the developed Qswitched laser and the construction of the necessary magnetostrictive modulator are also presented. Finally, the demonstrated mode field adaptor is described, with particular emphasis on the production process of fiber tapers, with the results both presented and discussed

An integrative assessment to determine the genotoxic hazard of estuarine sediments: combining cell and whole-organism responses

The application of the Comet assay in environmental monitoring remains challenging in face of the complexity of environmental stressors, e.g., when dealing with estuarine sediments, that hampers the drawing of cause-effect relationships. Although the in vitro Comet assay may circumvent confounding factors, its application in environmental risk assessment (ERA) still needs validation. As such, the present work aims at integrating genotoxicity and oxidative DNA damage induced by sediment-bound toxicants in HepG2 cells with oxidative stress-related effects observed in three species collected from an impacted estuary. Distinct patterns were observed in cells exposed to crude mixtures of sediment contaminants from the urban/industrial area comparatively to the ones from the rural/riverine area of the estuary, with respect to oxidative DNA damage and oxidative DNA damage. The extracts obtained with the most polar solvent and the crude extracts caused the most significant oxidative DNA damage in HepG2 cells, as measured by the formamidopyrimidine-DNA glycosylase (FPG)-modified Comet assay. This observation suggests that metals and unknown toxicants more hydrophilic than polycyclic aromatic hydrocarbons may be important causative agents, especially in samples from the rural part of the estuary, where oxidative DNA damage was the most significant. Clams, sole, and cuttlefish responded differentially to environmental agents triggering oxidative stress, albeit yielding results accordant with the oxidative DNA damage observed in HepG2 cells. Overall, the integration of in vivo biomarker responses and Comet assay data in HepG2 cells yielded a comparable pattern, indicating that the in vitro FPG-modified Comet assay may be an effective and complementary line-of-evidence in ERA even in particularly challenging, natural, scenarios such as estuarine environments

It comes from the sea: macroalgae-derived bioactive compounds with anti-cancer potential

Nature derived compounds represent a valuable source of bioactive molecules with enormous potential. The sea is one of the richest environments, full of skilled organisms, where algae stand out due to their unique characteristics. Marine macroalgae adapt their phenotypic characteristics, such as chemical composition, depending on the environmental conditions where they live. The compounds produced by these organisms show tremendous potential to be used in the biomedical field, due to their antioxidant, anti-inflammatory, immunomodulatory, and anti-cancer properties. Cancer is one of the deadliest diseases in the world, and the lack of effective treatments highlights the urgent need for the development of new therapeutic strategies. This review provides an overview of the current advances regarding the anti-cancer activity of the three major groups of marine macroalgae, i.e., red algae (Rhodophyta), brown algae (Phaeophyceae), and green algae (Chlorophyta) on pancreatic, lung, breast, cervical, colorectal, liver, and gastric cancers as well as leukemia and melanoma. In addition, future perspectives, and limitations regarding this field of work are also discussed.info:eu-repo/semantics/publishedVersio

Evaluation of risks at MANTEM

International statistics show that the problem of the accidents at work is far away to be solved (ILO estimates that every year about 270 million work accidents and 160 million occupational diseases resulting in the death of more than 2 million workers occurs in the world). That's why the EU global goal concerning the community' strategy for occupational health and safety for 2007-2012 is to reduce in 25% the incidence rate of occupational accidents and diseases. In this prospect it is presented a case study which justify the need to develop studies in Safety, Hygiene and Health at Work area as a way to encourage the managers to implement preventive actions and strategies, besides meeting the legal requirements, in order to reduce the occurrence of work accidents, improve the work conditions and therefore obtain benefits in added values and reinforced competition. The general objective of this study is to describe the work situations, identify the dangers and associate the potential risks and consequences; evaluate and value the risk. The study uses the Failure Table methodology and, in the business area of an organization which will be from now on designated as MANTEM that works in the electromechanical maintenance area. The results were, amongst others, some actions to be implemented to eliminate/minimize risks

Co-amorphization of olanzapine for solubility enhancement

Communication presented at the 3rd International Congress of CiiEM - Research and Innovation in Human and Health Sciences. Monte da Caparica, Portugal, 20-22 June 2018N/

Zenith e a construção do espaço subjetivo em Babbitt, de Sinclair Lewis

Zenith, o lexema escolhido para designar o espaço onde decorre a ação do romance Babbitt, convoca, desde logo, imagens de bem-estar e progresso que a focalização do narrador (heterodiegético) aparentemente corrobora: “THE towers of Zenith aspired above the morning mist […] They were neither citadels nor churches, but frankly and beautifully office-buildings. The whistles rolled out in greeting a chorus cheerful as the April dawn; the song of labor in a city built it seemed for giants” (Babbitt 6). Por contraste com a cidade, supostamente robusta e vibrante de energia, como se de um organismo vivo se tratasse, o protagonista, George F. Babbitt, não ostenta qualquer grandiosidade: “There was nothing of the giant in the aspect of the man who was beginning to awaken on the sleeping porch of a Dutch Colonial house in that residential district of Zenith known as Floral Heights” (6). Na verdade, do ponto de vista físico, Babbitt assemelha-se a um bebé: “His large head was pink […] His face was babyish in slumber” (6). Inúmeras referências a uma fada-criança com quem Babbitt mantém, em sonhos, uma relação afetiva, corroboram a ideia de que o protagonista é uma personagem infantilizada. Considere-se ainda que o encontro com a fada- -criança ocorre habitualmente num jardim ou outro espaço próximo da Natureza e que, para além deste aspeto, existe habitualmente uma alusão ao mar. Conjugados, estes espaços remetem para um (re) nascimento e este para o ventre materno, um estádio de dependência anterior ao (re) conhecimento da subjetividade. Babbitt é pois uma espécie de não-sujeito, facto que o torna ainda mais vulnerável aos mecanismos de controlo da comunidade/sociedade. Importa lembrar, a este propósito, que instituições comunitárias como a Igreja, um partido politico, uma associação ou clube social, o clube de futebol, etc, funcionam como um espelho doutrinário ou ideológico, onde o sujeito vê uma imagem gestaltiana de um corpo com o qual se identifica, por ser composto por sujeitos que se assemelham a si próprio, concitando-o a anularse voluntariamente, para poder participar da força que inere ao Todo, seja Deus, a Nação, ou outros grupos/ corpos colectivos. O grupo transforma-se assim numa espécie de Éden, um espaço quase transcendental, onde o sujeito sente que está em segurança (Hinshelwood 74). A construção do espaço subjetivo de Babbitt está, pois, simbiótica e indelevelmente subordinada ao espaço social de Zenith, pelo que, quando do fecho da narrativa, o leitor conclui que a Babbitt apenas lhe resta projetar sobre o seu filho Ted os desejos que um espaço social omnipotente sempre o obrigaria a sublimar: “I´ve never done a single thing I´ve wanted to in my whole life […] Well, those folks in there will try to bully you and tame you down…Tell ‘em to go to the devil! […]. Don´t be scared of the family. No, nor all of Zenith. Nor of yourself, the way I´ve been. Go ahead, old man! The world is yours!“(Babbitt 319

O movimento paranaense de matemática moderna: o papel do NEDEM

Disponível em: http://www2.pucpr.br/reol/pb/index.php/dialogo?dd1=581&dd99=view&dd98=pbNo final da década de 50, o impacto produzido pelo lançamento do Sputnik preocupou não somente o governo americano, mas também educadores de várias partes do mundo envolvidos com a formação científica da população. O êxito científico e tecnológico alcançado pelos russos ampliou a preocupação de vários países com a educação matemática oferecida à população, gerando um movimento internacional de reformulação do ensino de Matemática, conhecido como Movimento da Matemática Moderna, uma tentativa que nos anos 60 e 70 procurava superar o ensino tradicional que até a década de 50 privilegiava a matemática clássica, o modelo euclidiano, a visão platônica. No Brasil, esse movimento foi liderado pelo grupo paulista – GEEM - coordenado por Oswaldo Sangiorgi, incentivando a criação de grupos de estudos em vários estados com vistas à modernização da Matemática ensinada no ensino primário e ginasial (hoje Ensino Fundamental). No Paraná, o disseminador do Movimento da Matemática Moderna foi o NEDEM – Núcleo de Estudos e Difusão do Ensino da Matemática – criado e coordenado por Osny Antonio Dacol, diretor do Colégio Estadual do Paraná. Trabalhando inicialmente com classes experimentais no maior colégio do estado, o NEDEM elaborou sua proposta de Matemática Moderna que, posteriormente, foi publicada em duas coleções de livros didáticos que passaram a ser adotadas pelas escolas paranaenses durante mais de duas décadas. Tais iniciativas marcaram significativamente o ensino de Matemática no Paraná. A repercussão do movimento teve seu auge na década de 60 e no final de 1970 e mesmo com a extinção do grupo, as sementes plantadas pelos integrantes do NEDEM deixaram marcas na história da educação matemática paranaense, especialmente pelo intenso e democrático trabalho de difusão do movimento no ensino público do Paraná

The Scarcity Trap: How Perceptions Of Resource Immutability Reduces Scarcity-Induced Present Bias [abstract]

Pinto, D. C., Castagna, A. C., & Hidelbrand, D. (2023). The Scarcity Trap: How Perceptions of Resource Immutability Reduces Scarcity-Induced Present Bias [abstract]. In Proceedings of the European Marketing Academy, 52nd (pp. 1-2). [114324] European Marketing Academy (EMAC). https://proceedings.emac-online.org/pdfs/A2023-114324.pdfConsumers often find themselves trapped in a vicious cycle where financial resource scarcity decreases their psychological well-being, which in turn leads them to make present-biased financial decisions that contribute to the perpetuation of their condition. The present research explores how perceptions of resource immutability can help consumers disarm this scarcity trap. Results of six experiments (n = 1,801) and a secondary dataset (n = 51,288) reveal that perceptions of resource immutability reduce the present bias that characterizes the decisions of consumers facing scarcity episodes. Reported findings also show that this effect is contingent on consumers who perceive themselves to be socioeconomically vulnerable and is mediated by positive appraisals of the scarcity episodes. In addition to contributing to the literature on resource scarcity, this research provides substantial implications for interventions that can help consumers disarm the scarcity trap.publishersversionpublishe

Sustainability in the fashion industry

Castagna, A. C., Duarte, M., & Pinto, D. C. (2022). Slow fashion or self-signaling? Sustainability in the fashion industry. Sustainable Production and Consumption, 31(May), 582-590. https://doi.org/10.1016/j.spc.2022.03.024 ----------------Funding Information: This study was partially supported by Grant DSAIPA/DS/0113/2019 from the Foundation for Science and Technology of the Ministry of Science and Higher Education (Portugal).There has been a noteworthy rise in sustainability awareness in the fashion industry. However, the motivation to adopt such behaviors is unclear, making it relevant to consider which identity self-signals influences consumers' perceptions towards slow fashion. Findings from two experimental studies suggest that consumers hold a higher word of mouth (WOM) and status perceptions when non-conformity, pro-environmental, and frugality signals are highlighted. This research further shows the importance of increasing ownership through customization, which increases status. The findings provide key implications for researchers and practitioners regarding fashion industry sustainability.publishersversionpublishe