Automatic fatigue crack propagation calculation on welded high strength steels

Trabalho apresentado em XVI Portuguese Conference on Fracture 2018, 23-24 abril 2018, Covilhã, PortugalN/

Fatigue behavior of different geometry scaffolds for bone replacement

When transplanting bone tissue is not a possibility, tissue engineering is responsible for developing solutions to substitute the functions of the missing bone structure or support the process of bone regeneration. Scaffolds can be used to fulfill this mission by supporting loads that were applied to the missing bone, supporting the cell regenerating process, allowing for the necessary nutrients and oxygen diffusion and delivering growth factors or drugs. Scaffold geometry design must support static and dynamic loads up to 20 MPa in order to replace human trabecular bone. Also, it should generate macro and micro pores to support cell growth and mineral precipitation, while all pores should be interconnected for nutrient and oxygen diffusion. Scaffolds were fabricated according to ASTM-695 standard, using two different layouts, 50% porosity and a theoretical distance of 0.8 mm between each filament. A 400 µm diameter nozzle was used, and scaffolds were produced at 215 ºC with deposition rate of 30 mm/s. Both designs were fatigue tested until 3600 cycles, using different load amplitudes and a frequency of 0.25 Hz. The orthogonal scaffold showed improved behavior, with compression modulus reaching 680 MPa, when a maximum stress of 14.5 MPa was applied.info:eu-repo/semantics/publishedVersio

Long-term biosignals visualization and processing

Thesis submitted in the fulfillment of the requirements for the Degree of Master in Biomedical EngineeringLong-term biosignals acquisitions are an important source of information about the patients’state and its evolution. However, long-term biosignals monitoring involves managing extremely large datasets, which makes signal visualization and processing a complex task. To overcome these problems, a new data structure to manage long-term biosignals was developed. Based on this new data structure, dedicated tools for long-term biosignals visualization and processing were implemented. A multilevel visualization tool for any type of biosignals, based on subsampling is presented, focused on four representative signal parameters (mean, maximum, minimum and standard deviation error). The visualization tool enables an overview of the entire signal and a more detailed visualization in specific parts which we want to highlight, allowing an user friendly interaction that leads to an easier signal exploring. The ”map” and ”reduce” concept is also exposed for long-term biosignal processing. A processing tool (ECG peak detection) was adapted for long-term biosignals. In order to test the developed algorithm, long-term biosignals acquisitions (approximately 8 hours each) were carried out. The visualization tool has proven to be faster than the standard methods, allowing a fast navigation over the different visualization levels of biosignals. Regarding the developed processing algorithm, it detected the peaks of long-term ECG signals with fewer time consuming than the nonparalell processing algorithm. The non-specific characteristics of the new data structure, visualization tool and the speed improvement in signal processing introduced by these algorithms makes them powerful tools for long-term biosignals visualization and processing

IoT enabled aquatic drone for environment monitoring

This thesis presents a platform that tackles environment monitoring by using air and water quality sensors to provide data for the user to know what is happening in that surveilled area. The hardware is incorporated in a sensing module in order to be used with an Unmanned Surface Vehicle (USV). It presents a monitoring system based on Raspberry Pi platform and a multichannel sensing module associated with water quality and air quality measurement parameters. Thus, the temperature, relative humidity and gas concentration are measured as well as the underwater acoustic signals using a hydrophone. The data is stored on the memory of the drone’s computational platform (Raspberry Pi), and synchronized with a remote server database. Audio streaming capabilities were implemented in the server side. Additionally, a mobile application was developed to be used by people working in the field for data visualization, audio streaming playback and statistical analysis (by showing plotted data).O intuito desta dissertação é apresentar uma plataforma de monitorização ambiental através da instalação de sensores de qualidade do ar e da água de forma a fornecer dados ao utilizador daquela área vigiada. O hardware é apresentado num módulo onde estão presentes todos os componentes por forma a poder ser usado num drone aquático. É apresentado um sistema de monitorização baseado no sistema de processamento Raspberry Pi e um módulo multicanal de sensores de medição de qualidade do ar e qualidade da água. Sensores esses de medição da temperatura, humidade relativa e concentrações de gases tal como a medição de sinais de áudio debaixo de água com o uso de um hidrofone. Os dados estão alojados na memória do sistema computacional do drone (Raspberry Pi) e estão sincronizados com uma base de dados remota alojada num servidor cloud. Um sistema de streaming de áudio foi também implementado do lado do servidor. Adicionalmente, foi desenvolvida uma aplicação móvel que permite visualizar os dados provenientes dos sensores, reproduzir a stream de áudio e também analise de estatísticas (com apresentação gráfica dos dados)

55 years of the Infectious Diseases Service of Hospital de São João in Oporto - A Historical Perspective

Em outubro de 2019, celebrou-se os 55 anos do Serviço de Doenças Infeciosas do Hospital de São João, no Porto. Ao longo destes anos, os avanços tecnológicos e científicos, nomeadamente, a introdução do Plano Nacional de Vacinação, a optimização de terapêuticas, infraestruturas e equipamentos mais adequados e profissionais de saúde mais qualificados foram cruciais para enfrentar os desafios encarados pelo Serviço. Com esta dissertação pretende-se registar com o máximo rigor, que a memória dos intervenientes e os registos existentes permitirem, o percurso e a evolução deste Serviço ao longo destes 55 anos, considerando os grandes desafios, os acontecimentos mais relevantes e, por último, personalidades mais marcantes do Serviço.In October 2019 was celebrated the 55th anniversary of the Infectious Diseases Service of Hospital de São João, in Oporto, Portugal. Over the years, the scientific and technological advances namely, the introduction of the Nacional Vaccination Plan, therapeutic optimization, infrastructures and equipment improvements and healthcare professionals more qualified, were crucial to overcome the challenges faced by this Service. The purpose of this dissertation is to describe with the utmost rigor, allowed by the memory of the physicians and the existing records, the path and evolution of the Infectious Diseases Service of Hospital de São João over these 55 years, considering the major challenges, the most important milestones and, lastly, the Service´s most outstanding personalities

Clustering consumers who engage in boycotting: New insights into the relationship between political consumerism and institutional trust

This study proposes a segmentation model for European consumers engaging in boycotting and examines each segment’s level of trust in public institutions. Using data from the European Social Survey (ESS), measures of generalized trust, social participation, interest in politics, human values and demographics were used as segmentation variables in a two-cluster solution. The two clusters, labeled conservative majority and active idealists, revealed significant differences in their levels of institutional trust in 10 of the 21 countries analyzed. These findings highlight the potential heterogeneity of consumers engaging in boycotting and offer an explanation for extant contrasting findings regarding the relationship between institutional trust and political consumerism.info:eu-repo/semantics/publishedVersio

The role of succinate dehydrogenase in the Drosophila melanogaster intestinal stem cells and tissue homeostasis

Adult stem cells maintain tissue homeostasis and act in response to challenges such as infection or mechanical damage. The fruit fly Drosophila melanogaster has emerged as a powerful model to study adult stem cells due to its conserved pathways and the existence of different stem cell systems, particularly a stem cell niche in the intestine. Intestinal stem cells (ISCs) have a major role in maintaining tissue homeostasis and improvements in their function result in refined tissue function in aged or damaged organs. Metabolism plays an important role in regulating stem cell activity, influencing cellular events such as differentiation and proliferation. However, several aspects remain unraveled, particularly the role of different subunits of the mitochondrial electron transport chain (ETC) — end players in the oxidative phosphorylation process. Given the importance of metabolism in regulating stem cell activity, we hypothesized that ETC subunits also have a role in regulating ISC activity and tissue homeostasis. To test our hypothesis, we performed a candidate screen to knock down individual subunits of the ETC specifically in ISCs and their direct progeny — enteroblasts — in the adult fly and studied their requirements for normal cell division, differentiation, survival and impact in surrounding differentiated cells. Subunits of the ETC complex II, which converts succinate to fumarate in the Krebs cycle, particularly subunit D (SdhD), emerged from the screen as strong candidates required for normal ISC activity. Knockdown of SdhD in ISCs resulted in inhibition of cell division, hypertrophy with polyploidy, and ultimately, cell death. At a tissue level, evidence of a differentiation bias towards secretory enteroendocrine cells in lieu of absorptive enterocytes was observed upon SdhD knockdown in progenitor cells. Further experiments showed that knockdown of SdhD causes succinate to accumulate, possibly due to a decrease in the function of succinate dehydrogenase activity. Succinate is a known ligand for the GPR91 receptor in mammals which is known to be involved in cellular hypertrophy and death via apoptosis. Further studies need to be performed to determine the existence of a succinate receptor in Drosophila. This work has unveiled a direct relationship between inhibition of complex II subunits and stem cell hypertrophy and death, with succinate as a possible intermediate, and provides a suitable model for the study of the molecular pathways underlying cellular hypertrophy and death in metabolic-deficiency backgrounds. These insights may contribute to the understanding of hypertrophic pathologies, or proliferative diseases, such as cancer