349 results on '"João Faria"'
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2. Mesenchymal stromal cells secretome restores bioenergetic and redox homeostasis in human proximal tubule cells after ischemic injury
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João Faria, Sandra Calcat-i-Cervera, Renata Skovronova, Bonnie C. Broeksma, Alinda J. Berends, Esther A. Zaal, Benedetta Bussolati, Timothy O’Brien, Silvia M. Mihăilă, and Rosalinde Masereeuw
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Ischemia ,Proximal tubule ,Mesenchymal stromal cell ,Extracellular vesicles ,Metabolism ,Medicine (General) ,R5-920 ,Biochemistry ,QD415-436 - Abstract
Abstract Background Ischemia/reperfusion injury is the leading cause of acute kidney injury (AKI). The current standard of care focuses on supporting kidney function, stating the need for more efficient and targeted therapies to enhance repair. Mesenchymal stromal cells (MSCs) and their secretome, either as conditioned medium (CM) or extracellular vesicles (EVs), have emerged as promising options for regenerative therapy; however, their full potential in treating AKI remains unknown. Methods In this study, we employed an in vitro model of chemically induced ischemia using antimycin A combined with 2-deoxy-d-glucose to induce ischemic injury in proximal tubule epithelial cells. Afterwards we evaluated the effects of MSC secretome, CM or EVs obtained from adipose tissue, bone marrow, and umbilical cord, on ameliorating the detrimental effects of ischemia. To assess the damage and treatment outcomes, we analyzed cell morphology, mitochondrial health parameters (mitochondrial activity, ATP production, mass and membrane potential), and overall cell metabolism by metabolomics. Results Our findings show that ischemic injury caused cytoskeletal changes confirmed by disruption of the F-actin network, energetic imbalance as revealed by a 50% decrease in the oxygen consumption rate, increased oxidative stress, mitochondrial dysfunction, and reduced cell metabolism. Upon treatment with MSC secretome, the morphological derangements were partly restored and ATP production increased by 40–50%, with umbilical cord-derived EVs being most effective. Furthermore, MSC treatment led to phenotype restoration as indicated by an increase in cell bioenergetics, including increased levels of glycolysis intermediates, as well as an accumulation of antioxidant metabolites. Conclusion Our in vitro model effectively replicated the in vivo-like morphological and molecular changes observed during ischemic injury. Additionally, treatment with MSC secretome ameliorated proximal tubule damage, highlighting its potential as a viable therapeutic option for targeting AKI.
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- 2023
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3. Grassland vegetation height affects bird responses to forest edges in Mediterranean open farmland
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João Faria, Luís Reino, Pedro Beja, David Gonçalves, Juan S. Sánchez-Oliver, Francisco Moreira, Inês Catry, John T. Rotenberry, Rui Morgado, Lluís Brotons, Stefan Dullinger, Stefan Schindler, and Joana Santana
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Mediterranean farmland conservation ,Open farmland birds ,Vegetation height ,Plantation edges ,Steppe specialists ,Ecology ,QH540-549.5 - Abstract
Afforestation affects Mediterranean farmland biodiversity due to loss and fragmentation of grassland habitats. While the influence of landscape context and plantation edges on farmland bird responses to afforestation is well-documented, less is known about the influence of grassland vegetation height and how it interacts with afforestation to influence bird communities. Here, we examined how changes in grassland vegetation height affect bird responses to afforestation in a farmland region in southern Portugal, and how these are affected by plantation type and edge. This region has experienced afforestation with eucalyptus, pine and oak stands, agricultural intensification, and frequent dry periods. To capture local and landscape-level changes, we collected data in two periods (2005 and 2014–15). Grassland vegetation height varied between sampling periods, emerging as a key factor affecting changes observed. Ground-nesting and cereal-associated species increased in abundance with taller vegetation in 2014–15, while in 2005, with drier weather and shorter vegetation, the species associated with ploughed fields were more abundant. Vegetation height effects on bird assemblages depended on plantation type and distance to plantation edges. Farmland bird abundance, including ground-nesting and cereal crops-associated species, increased with taller vegetation, particularly near oak and pine plantations. Conversely, species associated with ploughed fields declined with taller vegetation, especially near eucalyptus plantations. Results highlight complex interactions between vegetation height, plantation type, and edge proximity shaping avian assemblages. This study supports the importance of field and landscape-level management with special focus on grassland vegetation height and landscape heterogeneity for preserving open-farmland birds in fast-changing Mediterranean farmland landscapes.
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- 2024
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4. Patterns of distribution of mollusc fauna associated with Halopteris scoparia (Linnaeus) Sauvageau: a baseline study in the Azores archipelago helps understanding the impact of climate change/invasive species on biodiversity
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Sérgio P. Ávila, Ana Cristina Costa, Patrícia Madeira, João Brum, Afonso C. L. Prestes, João Faria, and Gustavo M. Martins
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molluscs ,biodiversity ,patterns of distribution ,Halopteris scoparia ,Azores ,oceanic islands ,Science ,General. Including nature conservation, geographical distribution ,QH1-199.5 - Abstract
This work was done on 1996 and 1997, and presents an extremely valuable baseline to compare the recent and future changes on the insular shallow habitats of the Azorean islands. We examined the structure of the molluscan communities of the macroalgae Halopteris scoparia in São Miguel Island (Azores, Portugal). This island was chosen because it is the largest and the most populated of the archipelago, with polluted sites which are not common in the Azores. The relationship between the epifaunal assemblages and a set of environmental factors – geographical location (orientation), seawater temperature, depth, algal volume, degree of disturbance, and degree of exposure to the wave action – was investigated using distance-based redundancy analysis and significant variation in the distribution of richness of assemblages was found. Four environmental predictors were common to all the four analyses implemented (richness and assemblage structure using both AIC and BIC): algal volume (that correlates with algal dry weight), seawater temperature, coastal orientation and depth. Finally, the application in the Azores of this methodology favours a sampling program in Spring-Summer (when disturbance seems to be more susceptible to detection), and the use of H. scoparia in the subtidal zone, as the target alga is recommended due to its large covering of rocky shore substrates.
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- 2024
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5. Analysis of Petiole Sap Nutrients Using Rapid and Standard Methods and Its Relation to Leaf Analysis of Fertilized Malus domestica cv. Gala
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Mariana Mota, M. João Martins, Layanne Sprey, Anabela Maurício, Cristina Rosa, João Faria, Miguel B. Martins, Miguel L. de Sousa, Ricardo Santos, Rui M. de Sousa, Henrique Ribeiro, and Cristina M. Oliveira
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nutrient analysis methods ,fertilizer rate ,ion-selective strips read using reflectometry ,correlation ,Plant culture ,SB1-1110 - Abstract
Currently, fertilization decisions in apple orchards are based on soil and leaf analyses while the leaf material is sampled after the growing season, usually in June–July (90–110 days after full bloom). This approach is inefficient, as the information becomes available later than the growing season and is therefore only useful in supporting fertilization decisions for the next year, not the current one. To establish a method that provides useful information for fertilization decisions earlier in the growth cycle, our research focused on the assessment of the nutrient content of petiole sap using different methods, the standard method and the rapid method using a reflectometer. For this study, in 2021, four ‘Gala’ orchards were fertilized with different N–P–K levels. Macro and micronutrients were determined in leaves and petiole sap at 45 and 90–110 days after full bloom (DAFB) using standard laboratory methods and the reflectometer. When leaf analysis at 45 and 90–110 DAFB was compared with petiole sap analysis at the same time point, no significant correlations were found between the nutrient contents in leaf material and petiole sap, with the exception of calcium. However, positive results were obtained regarding the correlation between reflectometer determination and standard laboratory analyses. The regression analysis revealed high determination coefficients for N-NO3− (R2 = 0.703), K+ (R2 = 0.705), Ca2+ (R2 = 0.715), and Mg2+ (R2 = 0.780) between standard laboratory methods and the reflectometer. These results suggest that the reflectometer enables a real-time diagnostic tool for monitoring nutrient status throughout the growth cycle, particularly key nutrients related to fruit quality. The N–P–K fertilization strategies had no influence on the nutrient content of leaves or petiole sap. The nutrient content of both sample types varied depending on the orchard.
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- 2023
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6. Optimal Sizing of Renewable Energy Communities: A Multiple Swarms Multi-Objective Particle Swarm Optimization Approach
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João Faria, Carlos Marques, José Pombo, Sílvio Mariano, and Maria do Rosário Calado
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renewable energy community (REC) ,energy management strategies ,multi-objective optimization algorithm ,multi-swarm MOPSO ,energy storage systems ,energy storage sharing ,Technology - Abstract
Renewable energy communities have gained popularity as a means of reducing carbon emissions and enhancing energy independence. However, determining the optimal sizing for each production and storage unit within these communities poses challenges due to conflicting objectives, such as minimizing costs while maximizing energy production. To address this issue, this paper employs a Multi-Objective Particle Swarm Optimization (MOPSO) algorithm with multiple swarms. This approach aims to foster a broader diversity of solutions while concurrently ensuring a good plurality of nondominant solutions that define a Pareto frontier. To evaluate the effectiveness and reliability of this approach, four case studies with different energy management strategies focused on real-world operations were evaluated, aiming to replicate the practical challenges encountered in actual renewable energy communities. The results demonstrate the effectiveness of the proposed approach in determining the optimal size of production and storage units within renewable energy communities, while simultaneously addressing multiple conflicting objectives, including economic viability and flexibility, specifically Levelized Cost of Energy (LCOE), Self-Consumption Ratio (SCR) and Self-Sufficiency Ratio (SSR). The findings also provide valuable insights that clarify which energy management strategies are most suitable for this type of community.
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- 2023
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7. Intelligent Micro-Cogeneration Systems for Residential Grids: A Sustainable Solution for Efficient Energy Management
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Daniel Cardoso, Daniel Nunes, João Faria, Paulo Fael, and Pedro D. Gaspar
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micro-cogeneration systems ,internal combustion engines ,residential grids ,machine learning ,control strategies ,energy management ,Technology - Abstract
This paper presents an optimization approach for Micro-cogeneration systems with internal combustion engines integrated into residential grids, addressing power demand failures caused by intermittent renewable energy sources. The proposed method leverages machine learning techniques, control strategies, and grid data to improve system flexibility and efficiency in meeting electricity and domestic hot water demands. Historical residential grid data were analysed to develop a machine learning-based demand prediction model for electricity and hot water. Thermal energy storage was integrated into the Micro-cogeneration system to enhance flexibility. An optimization model was created, considering efficiency, emissions, and cost while adapting to real-time demand changes. A control strategy was designed for the flexible operation of the Micro-cogeneration system, addressing excess thermal energy storage and resource allocation. The proposed solution’s effectiveness was validated through simulations, with results demonstrating the Micro-cogeneration system’s ability to efficiently address high electricity and hot water demand periods while mitigating power demand failures from renewable energy sources. The research presents a novel approach with the potential to significantly improve grid resilience, energy efficiency, and renewable energy integration in residential grids, contributing to more sustainable and reliable energy systems.
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- 2023
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8. Human Cholangiocytes Form a Polarized and Functional Bile Duct on Hollow Fiber Membranes
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Zhenguo Wang, João Faria, Luc J. W. van der Laan, Louis C. Penning, Rosalinde Masereeuw, and Bart Spee
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intrahepatic cholangiocyte organoids ,cholangiocytes ,bioengineered bile duct ,hollow fiber membrane ,monolayer ,polarity ,Biotechnology ,TP248.13-248.65 - Abstract
Liver diseases affect hundreds of millions of people worldwide; most often the hepatocytes or cholangiocytes are damaged. Diseases of the biliary tract cause severe patient burden, and cholangiocytes, the cells lining the biliary tract, are sensitive to numerous drugs. Therefore, investigations into proper cholangiocyte functions are of utmost importance, which is restricted, in vitro, by the lack of primary human cholangiocytes allowing such screening. To investigate biliary function, including transepithelial transport, cholangiocytes must be cultured as three-dimensional (3D) ductular structures. We previously established murine intrahepatic cholangiocyte organoid-derived cholangiocyte-like cells (CLCs) and cultured them onto polyethersulfone hollow fiber membranes (HFMs) to generate 3D duct structures that resemble native bile ducts at the structural and functional level. Here, we established an efficient, stepwise method for directed differentiation of human intrahepatic cholangiocyte organoids (ICOs) into CLCs. Human ICO-derived CLCs showed key characteristics of cholangiocytes, such as the expression of structural and functional markers, formation of primary cilia, and P-glycoprotein-mediated transport in a polarized fashion. The organoid cultures exhibit farnesoid X receptor (FXR)-dependent functions that are vital to liver bile acid homeostasis in vivo. Furthermore, human ICO-derived CLCs cultured on HFMs in a differentiation medium form tubular architecture with some tight, confluent, and polarized monolayers that better mimic native bile duct characteristics than differentiated cultures in standard 2D or Matrigel-based 3D culture plates. Together, our optimized differentiation protocol to obtain CLC organoids, when applied on HFMs to form bioengineered bile ducts, will facilitate studying cholangiopathies and allow developing therapeutic strategies.
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- 2022
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9. A geometrical description of untwisted Dijkgraaf-Witten TQFT with defects
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Martins, João Faría and Meusburger, Catherine
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Mathematics - Quantum Algebra ,Mathematical Physics ,Mathematics - Category Theory ,Mathematics - Geometric Topology - Abstract
We give a simple, geometric and explicit construction of 3d untwisted Dijkgraaf-Witten theory with defects of all codimensions. It is given as a symmetric monoidal functor from a defect cobordism category into the category of finite-dimensional complex vector spaces. The objects of this category are oriented stratified surfaces and its morphisms are equivalence classes of stratified cobordisms, both labelled with higher categorical data. This TQFT is constructed in terms of geometric quantities such as fundamental groupoids and bundles and requires neither state sums on triangulations nor diagrammatic calculi for higher categories. It is obtained from a functor that assigns to each defect surface a representation of a gauge groupoid and to each defect cobordism a fibrant span of groupoids and an intertwiner between the groupoid representations at its boundary. It is constructed by homotopy theoretic methods and allows for an explicit computation of examples. In particular, we show how the 2d part of this defect TQFT gives a simple description of defects of all codimensions in Kitaev's quantum double model., Comment: 65 pages
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- 2024
10. Nutrient Content with Different Fertilizer Management and Influence on Yield and Fruit Quality in Apple cv. Gala
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Mariana Mota, Maria João Martins, Gonçalo Policarpo, Layanne Sprey, Mafalda Pastaneira, Patrícia Almeida, Anabela Maurício, Cristina Rosa, João Faria, Miguel B. Martins, Miguel L. de Sousa, Ricardo Santos, Rui M. de Sousa, Anabela B. da Silva, Henrique Ribeiro, and Cristina M. Oliveira
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bud ,flower ,leaves and fruit elements ,nutritional status ,chemical and organic fertilization ,productivity ,Plant culture ,SB1-1110 - Abstract
Assessing a plant’s nutritional status and fertilizer rates and types that can optimize fruit quality and yield are critical in intensive apple orchards. The aim of this work was to identify correlations between nutrients in the different organs that allow the early diagnosis of the nutritional status and to assess the impact on the optimal nutrient content in apple leaves, as well as in the yield and quality of chemical and organic fertilization. Five orchards of ‘Gala’ were fertilized with different levels of NPK over a period of four years. Macro and micronutrients of buds, flowers, 45 and 90–110 days after full bloom (DAFB) leaves and 60 DAFB and 15 days before harvest (DBH) fruits were determined. Boron was the only element for which strong correlations, 0.7 < r < 0.9, were observed between all organ pairs. The fertilization treatments did not affect the nutrient concentrations in the leaves of 90–110 DAFB other than P, Ca and Mg and did not affect the macronutrients in the fruit. In one of the five orchards, the yield increased by 26% with double fertilization compared to standard fertilization and, for the other four orchards, the impact depended on the year. Fruit size was more related to crop load than to fertilization and TSS and firmness were not affected by the type or amount of fertilizers. Replacing part of the chemical fertilizer with organic materials did not affect productivity or fruit quality.
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- 2022
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11. Viúva Mallen e Companhia(s)
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João Faria-Ferreira
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History of scholarship and learning. The humanities ,AZ20-999 ,History (General) ,D1-2009 - Abstract
Mariana Bourgeois, a Viúva Mallen, foi uma mulher invulgar que, no século XVIII, aproveitando-se da sua condição social, fundou a sua própria oficina de impressão no Porto. Neste trabalho procura-se, através de pesquisas nos arquivos, traçar uma biografia (familiar, social e profissional) de Mariana e de suas muitas companhias (Francisco Mallen, seu marido; João Roberto Bourgeois, seu irmão; entre outros) e expor a complexa rede familiar e comercial que une todos estes. Deste modo, pretende-se contribuir para futuras investigações sobre a história dos livreiros franceses em Portugal, com ainda tantas personagens por explorar.
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- 2020
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12. Carta ao Editor: O Papel dos Estudantes de Medicina na Pandemia de COVID-19 em Portugal
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Andreia Gi, Bárbara Rodrigues, João Dias-Ferreira, João Faria, João Fernandes Pedro, João Oliveira, Maria H. Viegas, and Marta Ribeiro
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Coronavírus ,COVID-19 ,Estudantes de Medicina ,Infecção de Coronavírus ,Pandemia ,Portugal ,Medicine ,Medicine (General) ,R5-920 - Abstract
N/a.
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- 2020
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13. Breast Cancer: Value-Based Healthcare, Costs and Financing
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Ana Harfouche, Silvia Silva, João Faria, Rui Araújo, António Gouveia, Maria Lacerda, and Luís D'Orey
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Análise Custo-Benefício ,Custos e Análise de Custo ,Custos em Saúde ,Neoplasias da Mama/economia ,Medicine ,Medicine (General) ,R5-920 - Abstract
Introduction: Breast cancer is the second most common oncological disease worldwide. To analyse the new disease specific funding programme (breast cancer) implemented at the Francisco Gentil Portuguese Institute of Oncology, Lisbon Center (Instituto Português de Oncologia de Lisboa Francisco Gentil), the actual costs of the patients were examined using activity-based costing as a costing methodology. This study addresses the following question: “How much does it cost to treat breast cancer per ‘patient-month’ compared to the monthly fixed ‘funding envelope’?”. Materials and Methods: The study cohort consisted of 807 patients, corresponding to all the patients eligible for the new disease specific funding programme and who were enrolled during the first year of implementation. Activity-based costing was used to calculate the total real costs per stage of disease and per ‘patient-month’ as well as the deviation from the monthly fixed ‘funding envelope’. Results: The total costs were 6.6 M€, whereas the total funding was 5.2 M€ for a total of 5648 ‘patient-months’. In 2014, the balance difference between the funding obtained and the actual costs was -1.4 €M for the cohort of 807 patients. Discussion: The extreme cases of differences in cost per ‘patient-month’ compared to the monthly fixed ‘funding envelope’ were (i) stage 0/Tis, with higher funding at 415.23 € per ‘patient-month’, and (ii) stage IIIC, with lower funding at 1062.79 € per ‘patient-month’. Conclusion: The ‘patient-month’ cost, regardless of disease stage was 1170.29 €. The median deviation per ‘patient-month’ was negative (241.21 €) compared to the monthly fixed ‘funding envelope’ of 929.08 € in the first year. Establishing activity-based costing - funding models will be crucial for the future sustainability of the healthcare sector.
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- 2017
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14. Long-Term Risk of Progression to Sustained Hypertension in White-Coat Hypertension with Normal Night-Time Blood Pressure Values
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João Faria, José Mesquita Bastos, Susana Bertoquini, José Silva, and Jorge Polónia
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Diseases of the circulatory (Cardiovascular) system ,RC666-701 - Abstract
Background. The long-term prognosis and transition towards sustained ambulatory hypertension (SHT) of white-coat hypertension (WCHT) remain uncertain particularly in those with both normal nighttime and daytime blood pressure (BP) values. Different classification criteria and the use of antihypertensive drugs may contribute to conflicting results. Patients and Methods. We prospectively evaluated for a 7.1 year transition to SHT in 899 nondiabetic subjects free from cardiovascular (CV) events: normotensive (NT) (n = 344; 52, 9% female; ageing 48 ± 14 years); untreated WCHT (UnWCHT n = 399; 50, 1% female; ageing 51 ± 14 years); and treated WCHT with antihypertensive drugs after baseline (TxWCHT n = 156; 54, 4% female; ageing 51 ± 15 years). All underwent 24 h ambulatory BP monitoring (24 h-ABPM) at baseline, at 30 to 60 months, and at 70 to 120 months thereafter. WCHT was at baseline (with no treatment) as office BP ≥ 140/or 90 mm·Hg, daytime BP
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- 2020
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15. Low-Cost IoT Remote Sensor Mesh for Large-Scale Orchard Monitorization
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Leonor Varandas, João Faria, Pedro Dinis Gaspar, and Martim L. Aguiar
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fruit tree diseases and pests ,smart agriculture ,IoT sensor mesh ,LPWAN communications ,photovoltaic power extraction ,Technology - Abstract
Population growth and climate change lead agricultural cultures to face environmental degradation and rising of resistant diseases and pests. These conditions result in reduced product quality and increasing risk of harmful toxicity to human health. Thus, the prediction of the occurrence of diseases and pests and the consequent avoidance of the erroneous use of phytosanitary products will contribute to improving food quality and safety and environmental land protection. This study presents the design and construction of a low-cost IoT sensor mesh that enables the remote measurement of parameters of large-scale orchards. The developed remote monitoring system transmits all monitored data to a central node via LoRaWAN technology. To make the system nodes fully autonomous, the individual nodes were designed to be solar-powered and to require low energy consumption. To improve the user experience, a web interface and a mobile application were developed, which allow the monitored information to be viewed in real-time. Several experimental tests were performed in an olive orchard under different environmental conditions. The results indicate an adequate precision and reliability of the system and show that the system is fully adequate to be placed in remote orchards located at a considerable distance from networks, being able to provide real-time parameters monitoring of both tree and the surrounding environment.
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- 2020
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16. Drugs Commonly Applied to Kidney Patients May Compromise Renal Tubular Uremic Toxins Excretion
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Silvia M. Mihaila, João Faria, Maurice F. J. Stefens, Dimitrios Stamatialis, Marianne C. Verhaar, Karin G. F. Gerritsen, and Rosalinde Masereeuw
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protein-bound uremic toxins ,chronic kidney disease management ,drug-toxin interaction ,OAT1-mediated transport ,Medicine - Abstract
In chronic kidney disease (CKD), the secretion of uremic toxins is compromised leading to their accumulation in blood, which contributes to uremic complications, in particular cardiovascular disease. Organic anion transporters (OATs) are involved in the tubular secretion of protein-bound uremic toxins (PBUTs). However, OATs also handle a wide range of drugs, including those used for treatment of cardiovascular complications and their interaction with PBUTs is unknown. The aim of this study was to investigate the interaction between commonly prescribed drugs in CKD and endogenous PBUTs with respect to OAT1-mediated uptake. We exposed a unique conditionally immortalized proximal tubule cell line (ciPTEC) equipped with OAT1 to a panel of selected drugs, including angiotensin-converting enzyme inhibitors (ACEIs: captopril, enalaprilate, lisinopril), angiotensin receptor blockers (ARBs: losartan and valsartan), furosemide and statins (pravastatin and simvastatin), and evaluated the drug-interactions using an OAT1-mediated fluorescein assay. We show that selected ARBs and furosemide significantly reduced fluorescein uptake, with the highest potency for ARBs. This was exaggerated in presence of some PBUTs. Selected ACEIs and statins had either no or a slight effect at supratherapeutic concentrations on OAT1-mediated fluorescein uptake. In conclusion, we demonstrate that PBUTs may compete with co-administrated drugs commonly used in CKD management for renal OAT1 mediated secretion, thus potentially compromising the residual renal function.
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- 2020
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17. Proportional Resonant Current Control and Output-Filter Design Optimization for Grid-Tied Inverters Using Grey Wolf Optimizer
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João Faria, João Fermeiro, José Pombo, Maria Calado, and Sílvio Mariano
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grid-tied inverter ,grey wolf optimizer ,PR controllers ,LCL filter ,passive damping ,Technology - Abstract
This paper proposes a new method for the simultaneous determination of the optimal control parameters of proportional resonant controllers and the optimal design of the output filter of a grid-tied three-phase inverter. The proposed method, based on the grey wolf optimization (GWO) algorithm, addresses both optimization problems as a single process to achieve a better system frequency response. It optimizes the unknown parameters by using a fitness function to find the best trade-off between the following fundamental terms: the harmonic attenuation rate; the power loss, through the damping resistor; and the current tracking error in the stationary frame, ensuring the system and grid stability. To validate the proposed optimization methodology, two case studies are considered with different output filter topologies with passive damping methods. The results obtained from the proposed optimization procedure were analyzed and discussed according to the fitness function terms.
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- 2020
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18. Power Management Control Strategy Based on Artificial Neural Networks for Standalone PV Applications with a Hybrid Energy Storage System
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João Faria, José Pombo, Maria do Rosário Calado, and Sílvio Mariano
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artificial neural network ,battery management system ,DC/DC converters ,energy storage system ,Li-ion battery pack ,maximum power point tracking ,particle swarm optimization ,power management strategy ,Technology - Abstract
Standalone microgrids with photovoltaic (PV) solutions could be a promising solution for powering up off-grid communities. However, this type of application requires the use of energy storage systems (ESS) to manage the intermittency of PV production. The most commonly used ESSs are lithium-ion batteries (Li-ion), but this technology has a low lifespan, mostly caused by the imposed stress. To reduce the stress on Li-ion batteries and extend their lifespan, hybrid energy storage systems (HESS) began to emerge. Although the utilization of HESSs has demonstrated great potential to make up for the limitations of Li-ion batteries, a proper power management strategy is key to achieving the HESS objectives and ensuring a harmonized system operation. This paper proposes a novel power management strategy based on an artificial neural network for a standalone PV system with Li-ion batteries and super-capacitors (SC) HESS. A typical standalone PV system is used to demonstrate and validate the performance of the proposed power management strategy. To demonstrate its effectiveness, computational simulations with short and long duration were performed. The results show a minimization in Li-ion battery dynamic stress and peak current, leading to an increased lifespan of Li-ion batteries. Moreover, the proposed power management strategy increases the level of SC utilization in comparison with other well-established strategies in the literature.
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- 2019
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19. The Darboux-KP system as an integrable Chern-Simons multiform theory in infinite dimensional space
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Martins, Joao Faria, Nijhoff, Frank W, and Riccombeni, Daniel
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Mathematical Physics ,High Energy Physics - Theory ,Nonlinear Sciences - Exactly Solvable and Integrable Systems - Abstract
In a previous paper by one of the authors, a Lagrangian 3-form structure was established for a generalised Darboux system, originally describing orthogonal curvilinear coordinate systems, which encodes the Kadomtsev-Petviashvili (KP) hierarchy. Here a hierarchy of Lagrangian multiforms is established for the same system, viewed as a hierarchy of Chern-Simons actions in an infinite-dimensional space of Miwa variables, constituting the variational form of a universal 3D integrable system embedded in this infinite-dimensional space.
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- 2023
20. Infecção pulmonar por rhodococcus equi em doente vih+ - revisão baseada num caso clínico
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João Faria, Joana Simões, Artur Silva, Eduardo Eiras, Maria João Soares, Mário Guimarães, Jorge Ferreira, and António Furtado
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Rhodococcus equi ,VIH ,infecção pulmonar ,malacoplaquia ,revisão ,Medicine ,Internal medicine ,RC31-1245 - Abstract
Apesar do aumento no número de casos de infecção humana por Rhodococcus equi (R. equi) registado nas últimas décadas, sobretudo em indivíduos infectados pelo vírus da imunodeficiência humana (VIH), esse diagnóstico permanece uma raridade. Os autores apresentam um caso de infecção pulmonar por R. equi num homem de 36 anos com síndrome de imunodeficiência adquirida (SIDA). A doença manifestou-se de forma insidiosa, apresentando-se radiologicamente sob a forma de lesão pulmonar esquerda com cavitação e nível hidroaéreo, tendo sido inicialmente colocada a hipótese diagnóstica de tuberculose pulmonar (TP) dada a pesquisa de bacilos álcool-ácido resistentes (BAAR) na expectoração ter sido positiva. Posteriormente, foi possível isolar o R. equi nas culturas de expectoração e lavado broncoalveolar (LBA). O estudo anátomo-patológico confirmou a presença concomitante de malacoplaquia pulmonar. O doente cumpriu antibioterapia dirigida ao agente e teve boa evolução clínica, analítica e radiológica. A propósito deste caso, os autores fazem uma revisão teórica do tema à luz dos conhecimentos actuais.
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- 2013
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21. A categorification of Quinn's finite total homotopy TQFT with application to TQFTs and once-extended TQFTs derived from strict omega-groupoids
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Martins, João Faria and Porter, Timothy
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Mathematics - Category Theory ,Mathematics - Algebraic Topology ,Mathematics - Geometric Topology ,Mathematics - Quantum Algebra - Abstract
We first revisit the construction of Quinn's Finite Total Homotopy TQFT, which depends on the choice of a homotopy finite space, $\boldsymbol{B}$. We build our construction directly from homotopy theoretical techniques, and hence, as in Quinn's original notes from 1995, the construction works in all dimensions. Our aim in this is to provide background for giving in detail the construction of a once-extended TQFT categorifying Quinn's TQFT, in the form of a symmetric monoidal bifunctor from the bicategory of manifolds, cobordisms and extended cobordisms, initially to the symmetric monoidal bicategory of profunctors (enriched over vector spaces), and then to the Morita bicategory of algebras, bimodules and bimodule maps. These once-extended versions of Quinn's TQFT likewise are defined for all dimensions, and, as with the original version, depend on the choice of a homotopy finite space $\boldsymbol{B}$. To show the utility of this approach, we explicitly compute both Quinn's finite total homotopy TQFT, and its extended version, for the case when $\boldsymbol{B}$ is the classifying space of a homotopically finite omega-groupoid, in this paper taking the form of a crossed complex, following Brown and Higgins. The constructions in this paper include, in particular, the description of once-extended TQFTs derived from the classifying space of a finite strict 2-group, of relevance for modelling discrete higher gauge theory, but the techniques involved are considerably more general., Comment: 235 pages
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- 2023
22. Proposal to Improve Risk Management in New Product Development Projects in an Automotive Company.
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Inês Laranjeiro, Anabela Tereso, and João Faria
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- 2024
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23. Exactly solvable models for 2+1D topological phases derived from crossed modules of semisimple Hopf algebras
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Koppen, Vincent, Martins, João Faria, and Martin, Paul Purdon
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Mathematical Physics ,High Energy Physics - Theory ,Mathematics - Quantum Algebra - Abstract
We define an exactly solvable model for 2+1D topological phases of matter on a triangulated surface derived from a crossed module of semisimple finite-dimensional Hopf algebras, the `Hopf-algebraic higher Kitaev model'. This model generalizes both the Kitaev quantum double model for a semisimple Hopf algebra and the full higher Kitaev model derived from a 2-group, and can hence be interpreted as a Hopf-algebraic discrete higher gauge theory. We construct a family of crossed modules of semisimple Hopf algebras, $(\mathscr{F}_{\mathbb{C}}(X) \otimes \mathbb{C}E \xrightarrow{\partial} \mathscr{F}_{\mathbb{C}}(Y) \rtimes \mathbb{C} G, \triangleright)$, that depends on four finite groups, $E,G,X$ and $Y$. We calculate the ground-state spaces of the resulting model on a triangulated surface when $G=E=\{1\}$ and when $Y=\{1\}$, prove that those ground-state spaces are canonically independent of the triangulations, and so depend only on the underlying surface; and moreover we find a 2+1D TQFT whose state spaces on surfaces give the ground-state spaces. These TQFTs are particular cases of Quinn's finite total homotopy TQFT and hence the state spaces assigned to surfaces are free vector spaces on sets of homotopy classes of maps from a surface to homotopy finite spaces, in this case obtained as classifying spaces of finite groupoids and finite crossed modules of groupoids. We leave it as an open problem whether the ground-state space of the Hopf-algebraic higher Kitaev model on a triangulated surface is independent of the triangulation for general crossed modules of semisimple Hopf algebras, whether a TQFT always exists whose state space on a surface gives the ground-state space of the model, and whether the ground-state space of the model obtained from $E,G,X,Y$ can always be given a homotopical explanation., Comment: v2: minor clarifications and corrections; 71 pages, 3 figures. v3: major revision; commutation relations between edge operators fixed; several new figures added, clarifying the construction; appendix with calculations considerably reduced; 57 pages, 14 figures. A corrected version will appear in Advances in Theoretical and Mathematical Physics
- Published
- 2021
24. Motion groupoids and mapping class groupoids
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Torzewska, Fiona, Martins, João Faria, and Martin, Paul Purdon
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Mathematical Physics ,Condensed Matter - Strongly Correlated Electrons ,High Energy Physics - Theory ,Mathematics - Category Theory ,Mathematics - Geometric Topology ,20F36 Braid groups, Artin groups, 20L05 Groupoids (i.e. small categories in which all morphisms are isomorphisms) - Abstract
Here $\underline{M}$ denotes a pair $(M,A)$ of a manifold and a subset (e.g. $A=\partial M$ or $A=\emptyset$). We construct for each $\underline{M}$ its motion groupoid $\mathrm{Mot}_{\underline{M}}$, whose object set is the power set $ {\mathcal P} M$ of $M$, and whose morphisms are certain equivalence classes of continuous flows of the `ambient space' $M$, that fix $A$, acting on ${\mathcal P} M$. These groupoids generalise the classical definition of a motion group associated to a manifold $M$ and a submanifold $N$, which can be recovered by considering the automorphisms in $\mathrm{Mot}_{\underline{M}}$ of $N\in {\mathcal P} M$. We also construct the mapping class groupoid $\mathrm{MCG}_{\underline{M}}$ associated to a pair $\underline{M}$ with the same object class, whose morphisms are now equivalence classes of homeomorphisms of $M$, that fix $A$. We recover the classical definition of the mapping class group of a pair by taking automorphisms at the appropriate object. For each pair $\underline{M}$ we explicitly construct a functor $\mathsf{F}\colon \mathrm{Mot}_{\underline{M}} \to \mathrm{MCG}_{\underline{M}}$, which is the identity on objects, and prove that this is full and faithful, and hence an isomorphism, if $\pi_0$ and $\pi_1$ of the appropriate space of self-homeomorphisms of $M$ are trivial. In particular, we have an isomorphism in the physically important case $\underline{M}=([0,1]^n, \partial [0,1]^n)$, for any $n\in \mathbb{N}$. We show that the congruence relation used in the construction $\mathrm{Mot}_{\underline{M}}$ can be formulated entirely in terms of a level preserving isotopy relation on the trajectories of objects under flows -- worldlines (e.g. monotonic `tangles'). We examine several explicit examples of $\mathrm{Mot}_{\underline{M}}$ and $\mathrm{MCG}_{\underline{M}}$ demonstrating the utility of the constructions., Comment: Version accepted for publication in CMP. 75 pages, 14 figures
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- 2021
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25. Zika: A Case Study.
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M. Filomena Teodoro and João Faria
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- 2023
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26. Towards Mobility Management in MEC Simulation.
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Paulo Araújo, Helena Fernández-López, João Faria, and Alexandre J. T. Santos
- Published
- 2023
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27. NETEDGE MEP: A CNF-based Multi-access Edge Computing Platform.
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Vinicius Ferreira, João Bastos, André Martins, Paulo Araújo, Nicolás F. Lori, João Faria, António Costa 0001, and Helena Fernández-López
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- 2023
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28. Duplicação da Veia Cava Inferior
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João Faria and Rui Moço
- Subjects
Duplicación de la vena cava inferior ,Medicine ,Internal medicine ,RC31-1245 - Abstract
Apresenta-se o caso de um doente do sexo masculino, com 83 anos de idade, que no decurso de investigação de quadro de suboclusão intestinal realizou uma tomografia axial computadorizada (TAC), que revelou a presença de duas veias cavas inferiores (setas brancas), unindo-se imediatamente na porção pré-hepática (variante do normal). Pode observar-se a artéria aorta, com calcificações, entre ambas as veias cavas inferiores. O desenvolvimento da veia cava ocorre entre a 6ª e 10ª semanas de gestação, a partir da veia supracardinal direita, enquanto que a veia supracardinal esquerda involui. A sua duplicação ocorre como resultado da persistência de ambas as veias supracardinais (direita e esquerda) e tem uma prevalência estimada de 0.2-0.3%. Geralmente, é uma anomalia assintomática, detectada acidentalmente em exames imagiológicos. Contudo, o seu diagnóstico é importante, uma vez que a sua presença tem implicações clínicas relevantes, nomeadamente no tratamento de doenças tromboembólicas.
- Published
- 2012
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29. Quisto pericárdico
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João Faria and Rui Moço
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Quiste pericárdico ,Medicine ,Internal medicine ,RC31-1245 - Abstract
Apresentam-se dois casos de quisto pericárdico diagnosticados acidentalmente em exames de imagem de rotina. Ambos os doentes, uma mulher de 18 anos (fig. A y B) e um homem de 83 anos (fig. 2 A y B), não apresentavam qualquer sintoma relacionável com a presença de quisto pericárdico. Realizaram em consulta de rotina uma telerradiografia de tórax, que em ambos os casos mostrou uma imagem hiperdensa, arredondada e homogénea, no ângulo cardiofrénico direito. Para esclarecimento das referidas imagens, ambos os doentes realizaram Tomografia axial computorizada (TAC). Em ambos os casos a TAC confirmou a presença de uma massa homogénea no ângulo cardiofrénico direito, de densidade hídrica, não captante de contraste, a traduzir quisto pericárdico.Os quistos pericárdicos são uma anomalia rara (com uma incidência de 1/100000), benigna, e na maioria dos casos congénita. Em 75% dos casos, são encontrados de forma acidental em exames de imagem de rotina de doentes assintomáticos. Os quistos assintomáticos devem ser abordados conservadoramente
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- 2012
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30. Four-Dimensional Spin Foam Perturbation Theory
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João Faria Martins and Aleksandar Mikovic
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spin foam models ,BF-theory ,spin networks ,dilute-gas limit ,Crane-Yetter invariant ,spin-foam perturbation theory ,Mathematics ,QA1-939 - Abstract
We define a four-dimensional spin-foam perturbation theory for the BF-theory with a B∧B potential term defined for a compact semi-simple Lie group G on a compact orientable 4-manifold M. This is done by using the formal spin foam perturbative series coming from the spin-foam generating functional. We then regularize the terms in the perturbative series by passing to the category of representations of the quantum group U_q(g) where g is the Lie algebra of G and q is a root of unity. The Chain-Mail formalism can be used to calculate the perturbative terms when the vector space of intertwiners Λ⊗Λ→A, where A is the adjoint representation of g, is 1-dimensional for each irrep Λ. We calculate the partition function Z in the dilute-gas limit for a special class of triangulations of restricted local complexity, which we conjecture to exist on any 4-manifold M. We prove that the first-order perturbative contribution vanishes for finite triangulations, so that we define a dilute-gas limit by using the second-order contribution. We show that Z is an analytic continuation of the Crane-Yetter partition function. Furthermore, we relate Z to the partition function for the F∧F theory.
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- 2011
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31. On a canonical lift of Artin's representation to loop braid groups
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Damiani, Celeste, Martins, João Faria, and Martin, Paul Purdon
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Mathematics - Geometric Topology ,Mathematics - Quantum Algebra - Abstract
Each pointed topological space has an associated $\pi$-module, obtained from action of its first homotopy group on its second homotopy group. For the $3$-ball with a trivial link with $n$-components removed from its interior, its $\pi$-module $\mathcal{M}_n$ is of free type. In this paper we give an injection of the (extended) loop braid group into the group of automorphisms of $\mathcal{M}_n$. We give a topological interpretation of this injection, showing that it is both an extension of Artin's representation for braid groups and of Dahm's homomorphism for (extended) loop braid groups., Comment: All comments are welcome!
- Published
- 2019
32. Enriching a Fashion Knowledge Graph from Product Textual Descriptions.
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João Barroca, Abhishek Shivkumar, Beatriz Quintino Ferreira, Evgeny Sherkhonov, and João Faria
- Published
- 2022
33. Representations of the Loop Braid Group and Aharonov-Bohm like effects in discrete (3+1)-dimensional higher gauge theory
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Bullivant, Alex, Martins, João Faria, and Martin, Paul
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Mathematical Physics ,High Energy Physics - Theory ,Mathematics - Geometric Topology ,Mathematics - Quantum Algebra - Abstract
We show that representations of the loop braid group arise from Aharonov-Bohm like effects in finite 2-group (3+1)-dimensional topological higher gauge theory. For this we introduce a minimal categorification of biracks, which we call W-bikoids (welded bikoids). Our main example of W-bikoids arises from finite 2-groups, realised as crossed modules of groups. Given a W-bikoid, and hence a groupoid of symmetries, we construct a family of unitary representations of the loop braid group derived from representations of the groupoid algebra. We thus give a candidate for higher Bais' flux metamorphosis, and hence also a version of a `higher quantum group'., Comment: V2. Slightly abridged version. Rewording of title. 48 pages. Several minor clarifications, corrections and improvements
- Published
- 2018
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34. Automatic sunspot detection through semantic and instance segmentation approaches.
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André Mourato, João Faria, and Rodrigo Ventura 0001
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- 2024
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35. Flora da Serra de Itabirito, Minas Gerais: primeira contribuição
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Mitzi Brandão, Manuel Losada Gavilanes, Julio Pedro Laca-Buendia, Lucia Helena de S Cunha, and João Faria de Macedo
- Subjects
Flora de Minas Gerais ,Cerrado ,Campo-rupestre ,Flora of State of Minas Gerais ,"Cerrado ,"Campo-rupestre ,Botany ,QK1-989 - Abstract
Foi efetuado o levantamento das espécies ocorrentes na Serra de Itabirito, Município de Itabirito, Minas Gerais, em áreas de cerrado e campo-rupestre. Nesta primeira etapa foram coletadas e identificadas 366 espécies, pertencentes a 209 gêneros, agrupadas em 78 famílias. Compositae é a família mais representativa, com cerca de 57 espécies e 22 gêneros, vindo a seguir Leguminosae com 37 espécies e 14 gêneros e Gramineae com 14 espécies e 13 gêneros.This study is a survey of species occuring in the "cerrado" and "campo-rupreste" of Itabirito Hills, County of Itabirito, State of Minas Gerais, Brazil. In this first stage we collected and identified 366 species, belonging to 209 genera, grouped into 78 families. Compositae was the most representative family having 57 species and 22 genera, followed by Leguminosae with 37 species and 14 genera, and Gramineae with 14 species and 13 genera.
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- 1989
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36. Higher lattices, discrete two-dimensional holonomy and topological phases in (3+1) D with higher gauge symmetry
- Author
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Bullivant, Alex, Calcada, Marcos, Kádár, Zoltán, Martins, João Faria, and Martin, Paul
- Subjects
Mathematical Physics ,Condensed Matter - Strongly Correlated Electrons ,High Energy Physics - Theory - Abstract
Higher gauge theory is a higher order version of gauge theory that makes possible the definition of 2-dimensional holonomy along surfaces embedded in a manifold where a gauge 2-connection is present. In this paper, we will continue the study of Hamiltonian models for discrete higher gauge theory on a lattice decomposition of a manifold. In particular, we show that a previously proposed construction for higher lattice gauge theory is well-defined, including in particular a Hamiltonian for topological phases of matter in 3+1 dimensions. Our construction builds upon the Kitaev quantum double model, replacing the finite gauge connection with a finite gauge 2-group 2-connection. Our Hamiltonian higher lattice gauge theory model is defined on spatial manifolds of arbitrary dimension presented by slightly {\it combinatorialised} CW-decompositions (2-lattice decompositions), whose 1-cells and 2-cells carry discrete 1-dimensional and 2-dimensional holonomy data. We prove that the ground-state degeneracy of Hamiltonian higher lattice gauge theory is a topological invariant of manifolds, coinciding with the number of homotopy classes of maps from the manifold to the classifying space of the underlying gauge 2-group. The operators of our Hamiltonian model are closely related to discrete 2-dimensional holonomy operators for discretised 2-connections on manifolds with a 2-lattice decomposition. We therefore address the definition of discrete 2-dimensional holonomy for surfaces embedded in 2-lattices. Several results concerning the well-definedness of discrete 2-dimensional holonomy, and its construction in a combinatorial and algebraic topological setting are presented., Comment: V3: Major revision. Clarification of the action of vertex and edge operators. 52 pages, 18 figures. V4: Minor corrections. 53 pages, 18 figures
- Published
- 2017
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37. Link invariants from finite categorical groups
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Martins, Joao Faria and Picken, Roger
- Subjects
Mathematics - Geometric Topology - Abstract
We define an invariant of tangles and framed tangles given a finite crossed module and a pair of functions, called a Reidemeister pair, satisfying natural properties. We give several examples of Reidemeister pairs derived from racks, quandles, rack and quandle cocycles, and central extensions of groups. We prove that our construction includes all rack and quandle cohomology (framed) link invariants, as well as the Eisermann invariant of knots. We construct a class of Reidemeister pairs which constitute a lifting of the Eisermann invariant, and show through an example that this class is strictly stronger than the Eisermann invariant itself., Comment: This is an abridged version of arXiv:1301.3803 [math.GT]
- Published
- 2016
38. Topological phases from higher gauge symmetry in 3+1D
- Author
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Bullivant, Alex, Calçada, Marcos, Kádár, Zoltán, Martin, Paul, and Martins, João Faria
- Subjects
Condensed Matter - Strongly Correlated Electrons ,High Energy Physics - Lattice ,Mathematical Physics - Abstract
We propose an exactly solvable Hamiltonian for topological phases in $3+1$ dimensions utilising ideas from higher lattice gauge theory, where the gauge symmetry is given by a finite 2-group. We explicitly show that the model is a Hamiltonian realisation of Yetter's homotopy 2-type topological quantum field theory whereby the groundstate projector of the model defined on the manifold $M^3$ is given by the partition function of the underlying topological quantum field theory for $M^3\times [0,1]$. We show that this result holds in any dimension and illustrate it by computing the ground state degeneracy for a selection of spatial manifolds and 2-groups. As an application we show that a subset of our model is dual to a class of Abelian Walker-Wang models describing $3+1$ dimensional topological insulators., Comment: 28 pages, 4 figures
- Published
- 2016
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39. Two-Fold Homotopy of 2-Crossed Module Maps of Commutative Algebras
- Author
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Akça, İ. İlker, Emir, Kadir, and Martins, João Faria
- Subjects
Mathematics - Category Theory ,Mathematics - Algebraic Topology ,55U10 (principal), 18D05, 18D20, 55Q15 (secondary) - Abstract
We address the homotopy theory of 2-crossed modules of commutative algebras. In particular, we define the concept of a 2-fold homotopy between a pair of 1-fold homotopies connecting 2-crossed module maps $\A \to \A'$. We also prove that if the domain 2-crossed module $\A$ is free up to order one (i.e. if the bottom algebra is a polynomial algebra) then we have a 2-groupoid of 2-crossed module maps $\A \to \A'$ and their homotopies and 2-fold homotopies., Comment: 24 pages, to appear in Communications in Algebra
- Published
- 2015
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40. Crossed modules of Hopf algebras and of associative algebras and two-dimensional holonomy
- Author
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Martins, Joao Faria
- Subjects
Mathematics - Quantum Algebra ,High Energy Physics - Theory ,Mathematics - Category Theory - Abstract
After a thorough treatment of all algebraic structures involved, we address two dimensional holonomy operators with values in crossed modules of Hopf algebras and in crossed modules of associative algebras (called here crossed modules of bare algebras.) In particular, we will consider two general formulations of the two-dimensional holonomy of a (fully primitive) Hopf 2-connection (exact and blur), the first being multiplicative the second being additive, proving that they coincide in a certain natural quotient (defining what we called the fuzzy holonomy of a fully primitive Hopf 2-connection)., Comment: 48 Pages
- Published
- 2015
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41. Pointed Homotopy of Maps Between 2-Crossed Modules of Commutative Algebras
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Akça, İ. İlker, Emir, Kadir, and Martins, João Faria
- Subjects
Mathematics - Category Theory ,Mathematics - Algebraic Topology ,55U10 (principal), 18D05, 18D20, 55Q15 (secondary) - Abstract
We address the homotopy theory of 2-crossed modules of commutative algebras, which are equivalent to simplicial commutative algebras with Moore complex of length two. In particular, we construct for maps of 2-crossed modules a homotopy relation, and prove that it yields an equivalence relation in very unrestricted cases (freeness up to order one of the domain 2-crossed module). This latter condition strictly includes the case when the domain is cofibrant. Furthermore, we prove that this notion of homotopy yields a groupoid with objects being the 2-crossed module maps between two fixed 2-crossed modules (with free up to order one domain), the morphisms being the homotopies between 2-crossed module maps., Comment: 29 pages, Final version to appear in HHA
- Published
- 2014
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42. Project management under uncertainty: resource flexibility visualization in the schedule.
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Ricardo Lima, Anabela Tereso, and João Faria
- Published
- 2019
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43. Knowledge of the Boarded Population About Zika Virus.
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João Faria, Rosa Teodósio, and M. Filomena Teodoro
- Published
- 2019
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44. Infinitesimal 2-braidings and differential crossed modules
- Author
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Cirio, Lucio S. and Martins, João Faria
- Subjects
Mathematics - Category Theory ,High Energy Physics - Theory ,Mathematics - Geometric Topology ,Mathematics - Quantum Algebra ,16T25, 18D05, 20F36, 17B37 - Abstract
We categorify the notion of an infinitesimal braiding in a linear strict symmetric monoidal category, leading to the notion of a (strict) infinitesimal 2-braiding in a linear symmetric strict monoidal 2-category. We describe the associated categorification of the 4-term relation, leading to six categorified relations. We prove that any infinitesimal 2-braiding gives rise to a flat and fake flat 2-connection in the configuration space of $n$ particles in the complex plane, hence to a categorification of the Knizhnik-Zamolodchikov connection. We discuss infinitesimal 2-braidings in a 2-category naturally assigned to every differential crossed module, leading to the notion of a quasi-invariant tensor in a differential crossed module. Finally we prove that quasi-invariant tensors exist in the differential crossed module associated to the String Lie-2-algebra., Comment: v3 - the introduction has been expanded, overall improvements in the presentation. Final version, to appear in Adv. Math
- Published
- 2013
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45. Link invariants from finite categorical groups and braided crossed modules
- Author
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Martins, João Faria and Picken, Roger
- Subjects
Mathematics - Geometric Topology ,Mathematics - Algebraic Topology ,Mathematics - Quantum Algebra ,57M25, 57M27 (Primary) 18D10 (Secondary) - Abstract
We define an invariant of tangles and framed tangles given a finite crossed module and a pair of functions, called a Reidemeister pair, satisfying natural properties. We give several examples of Reidemeister pairs derived from racks, quandles, rack and quandle cocycles, 2-crossed modules and braided crossed modules. We prove that our construction includes all rack and quandle cohomology (framed) link invariants, as well as the Eisermann invariant of knots, for which we also find a lifting by using braided crossed modules., Comment: 41 pages, 19 figures. This version 2 has minor corrections and additions, mainly in the references
- Published
- 2013
46. Pointed homotopy and pointed lax homotopy of 2-crossed module maps
- Author
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Gohla, Bjorn and Martins, Joao Faria
- Subjects
Mathematics - Category Theory ,Mathematics - Algebraic Topology ,18D05, 18D20 (Primary), 55Q15 (Secondary) - Abstract
We address the (pointed) homotopy theory of 2-crossed modules (of groups), which are known to faithfully represent Gray 3-groupoids, with a single object, and also connected homotopy 3-types. The homotopy relation between 2-crossed module maps will be defined in a similar way to Crans' 1-transfors between strict Gray functors, however being pointed, thus this corresponds to Baues' homotopy relation between quadratic module maps. Despite the fact that this homotopy relation between 2-crossed module morphisms is not, in general, an equivalence relation, we prove that if $A$ and $A'$ are 2-crossed modules, with the underlying group $F$ of $A$ being free (in short $A$ is free up to order one), then homotopy between 2-crossed module maps $A \to A'$ yields, in this case, an equivalence relation. Furthermore, if a chosen basis $B$ is specified for $F$, then we can define a 2-groupoid $HOM_B(A,A')$ of 2-crossed module maps $A \to A'$, homotopies connecting them, and 2-fold homotopies between homotopies, where the latter correspond to (pointed) Crans' 2-transfors between 1-transfors. We define a partial resolution $Q^1(A)$, for a 2-crossed module $A$, whose underlying group is free, with a canonical chosen basis, together with a projection map ${\rm proj}\colon Q^1(A) \to A$, defining isomorphisms at the level of 2-crossed module homotopy groups. This resolution (which is part of a comonad) leads to a weaker notion of homotopy (lax homotopy) between 2-crossed module maps, which we fully develop and describe. In particular, given 2-crossed modules $A$ and $A'$, there exists a 2-groupoid ${HOM}_{\rm LAX}(A,A')$ of (strict) 2-crossed module maps $A \to A'$, and their lax homotopies and lax 2-fold homotopies. The associated notion of a (strict) 2-crossed module map $f\colon A \to A'$ to be a lax homotopy equivalence has the two-of-three property, and it is closed under retracts., Comment: v3: Major revision. A perfected version will appear in Advances in Mathematics
- Published
- 2012
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47. Categorifying the $sl(2,C)$ Knizhnik-Zamolodchikov Connection via an Infinitesimal 2-Yang-Baxter Operator in the String Lie-2-Algebra
- Author
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Cirio, Lucio S. and Martins, João Faria
- Subjects
High Energy Physics - Theory ,Mathematics - Geometric Topology ,Mathematics - Quantum Algebra ,16T25, 20F36 (principal), 18D05, 17B37, 53C29, 57M25, 57Q45 (secondary) - Abstract
We construct a flat (and fake-flat) 2-connection in the configuration space of $n$ indistinguishable particles in the complex plane, which categorifies the $sl(2,C)$-Knizhnik-Zamolodchikov connection obtained from the adjoint representation of $sl(2,C)$. This will be done by considering the adjoint categorical representation of the string Lie 2-algebra and the notion of an infinitesimal 2-Yang-Baxter operator in a differential crossed module. Specifically, we find an infinitesimal 2-Yang-Baxter operator in the string Lie 2-algebra, proving that any (strict) categorical representation of the string Lie-2-algebra, in a chain-complex of vector spaces, yields a flat and (fake flat) 2-connection in the configuration space, categorifying the $sl(2,C)$-Knizhnik-Zamolodchikov connection. We will give very detailed explanation of all concepts involved, in particular discussing the relevant theory of 2-connections and their two dimensional holonomy, in the specific case of 2-groups derived from chain complexes of vector spaces., Comment: The main result was considerably sharpened. Title, abstract and introduction updated. 50 pages
- Published
- 2012
48. Categorifying the Knizhnik-Zamolodchikov Connection
- Author
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Cirio, Lucio S. and Martins, João Faria
- Subjects
High Energy Physics - Theory ,Mathematics - Category Theory ,Mathematics - Quantum Algebra ,16T25 20F36 (Primary) 18D05 17B37 53C29 57Q45 (Secondary) - Abstract
In the context of higher gauge theory, we construct a flat and fake flat 2-connection, in the configuration space of $n$ particles in the complex plane, categorifying the Knizhnik-Zamolodchikov connection. To this end, we define the differential crossed module of horizontal 2-chord diagrams, categorifying the Lie algebra of horizontal chord diagrams in a set of $n$ parallel copies of the interval. This therefore yields a categorification of the 4-term relation. We carefully discuss the representation theory of differential crossed modules in chain-complexes of vector spaces, which makes it possible to formulate the notion of an infinitesimal 2-R matrix in a differential crossed module., Comment: 30 pages, 2 figures; v3: final version to be published in Differential Geometry and its Applications
- Published
- 2011
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49. Lie crossed modules and gauge-invariant actions for 2-BF theories
- Author
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Martins, Joao Faria and Mikovic, Aleksandar
- Subjects
High Energy Physics - Theory ,General Relativity and Quantum Cosmology ,Mathematical Physics - Abstract
We generalize the BF theory action to the case of a general Lie crossed module $(H \to G)$, where $G$ and $H$ are non-abelian Lie groups. Our construction requires the existence of $G$-invariant non-degenerate bilinear forms on the Lie algebras of $G$ and $H$ and we show that there are many examples of such Lie crossed modules by using the construction of crossed modules provided by short chain complexes of vector spaces. We also generalize this construction to an arbitrary chain complex of vector spaces, of finite type. We construct two gauge-invariant actions for 2-flat and fake-flat 2-connections with auxiliary fields. The first action is of the same type as the BFCG action introduced by Girelli, Pfeiffer and Popescu for a special class of Lie crossed modules, where $H$ is abelian. The second action is an extended BFCG action which contains an additional auxiliary field. However, these two actions are related by a field redefinition. We also construct a three-parameter deformation of the extended BFCG action, which we believe to be relevant for the construction of non-trivial invariants of knotted surfaces embedded in the four-sphere., Comment: 22 pages. A three-parameter deformation of the extended BFCG action is included. Minor corrections
- Published
- 2010
50. Spin Foam State Sums and Chern-Simons Theory
- Author
-
Mikovic, Aleksandar and Martins, Joao Faria
- Subjects
High Energy Physics - Theory ,General Relativity and Quantum Cosmology ,Mathematical Physics - Abstract
We review the spin foam state-sum invariants of 3-manifolds, and explain their relationship to manifold invariants coming from the Chern-Simons theory. We also explain the relationship between the known invariants of spin networks by using the Chain-Mail formalism of J. Roberts. This formalism can be understood as a quantum-group regularization of the BF theory path integrals., Comment: 8 pages. Talk presented by A. Mikovic at "Chern-Simons Gauge Theory: Twenty years after" conference, Bonn, 3-7 August 2009
- Published
- 2010
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