Codificação distribuída em sistemas com diversidade cooperativa

Doutoramento em Engenharia ElectrotécnicaO presente trabalho propõe-se a divulgar as mais significativas técnicas de esquemas cooperativos, de forma a ultrapassar alguns dos problemas dos sistemas móveis sem fios da próxima geração, estendendo a área de cobertura destes sistemas, assim como a sua capacidade e fiabilidade. O estudo de diversos esquemas cooperativos é efetuado em termos de capacidade e de taxa de erros, fazendo variar o número de relays e de antenas em cada elemento do sistema. Diversos algoritmos com aplicação em sistemas cooperativos são desenvolvidos e propostos ao longo desta tese, como códigos espaço-frequência aplicados de forma distribuída nos relays, para sistemas baseados na tecnologia OFDM e sob diversos cenários próximos da realidade. Os sistemas cooperativos são particularmente úteis em situações em que o caminho direto entre dois terminais não está acessível ou tem uma fraca qualidade de transmissão. Tendo este aspeto em consideração, e pretendendo ter a máxima eficiência espetral e máxima diversidade, um algoritmo com precodificação é também proposto para múltiplos relays, cada um equipado com uma ou duas antenas. A formulação matemática associada aos algoritmos propostos é apresentada, assim como a derivação da probabilidade de erro teórica. O desempenho dos sistemas assistidos por relays usando os algoritmos propostos é comparado em relação a outros esquemas cooperativos equivalentes e a esquemas não-cooperativos, considerando cenários com diferentes qualidades de canal, daí advindo importantes conclusões em relação a estes sistemas.Cooperative schemes are promising solutions for cellular wireless networks aiming to improve system fairness, extend coverage and increase capacity. Measurements of these system performances are made in terms of BER and capacity for different configurations, by varying the number of relays and of antennas equipping each node. In this work we propose and evaluate distributed space-frequency codes applied to cooperative systems in a distributed way, with application in OFDM systems and considering realistic scenarios. Moreover, the use of relays is of significant interest to allow radio access in situations where a direct path is not available or has poor quality. Thus, a data precoded relay-assisted scheme is also proposed for a system cooperating with multiple relays, each equipped with either a single antenna or two-antenna array. Mathematical formulation of the proposed algorithms is derived as well as the pairwise error probability. We further present the performances of the proposed algorithms apllied in relay-assisted schemes, and compare them with equivalent cooperative and non-cooperative schemes, for several channel quality scenarios, through which important conclusions are achieved.FCT/FS

ATLANTIC EPIPHYTES: a data set of vascular and non-vascular epiphyte plants and lichens from the Atlantic Forest

Epiphytes are hyper-diverse and one of the frequently undervalued life forms in plant surveys and biodiversity inventories. Epiphytes of the Atlantic Forest, one of the most endangered ecosystems in the world, have high endemism and radiated recently in the Pliocene. We aimed to (1) compile an extensive Atlantic Forest data set on vascular, non-vascular plants (including hemiepiphytes), and lichen epiphyte species occurrence and abundance; (2) describe the epiphyte distribution in the Atlantic Forest, in order to indicate future sampling efforts. Our work presents the first epiphyte data set with information on abundance and occurrence of epiphyte phorophyte species. All data compiled here come from three main sources provided by the authors: published sources (comprising peer-reviewed articles, books, and theses), unpublished data, and herbarium data. We compiled a data set composed of 2,095 species, from 89,270 holo/hemiepiphyte records, in the Atlantic Forest of Brazil, Argentina, Paraguay, and Uruguay, recorded from 1824 to early 2018. Most of the records were from qualitative data (occurrence only, 88%), well distributed throughout the Atlantic Forest. For quantitative records, the most common sampling method was individual trees (71%), followed by plot sampling (19%), and transect sampling (10%). Angiosperms (81%) were the most frequently registered group, and Bromeliaceae and Orchidaceae were the families with the greatest number of records (27,272 and 21,945, respectively). Ferns and Lycophytes presented fewer records than Angiosperms, and Polypodiaceae were the most recorded family, and more concentrated in the Southern and Southeastern regions. Data on non-vascular plants and lichens were scarce, with a few disjunct records concentrated in the Northeastern region of the Atlantic Forest. For all non-vascular plant records, Lejeuneaceae, a family of liverworts, was the most recorded family. We hope that our effort to organize scattered epiphyte data help advance the knowledge of epiphyte ecology, as well as our understanding of macroecological and biogeographical patterns in the Atlantic Forest. No copyright restrictions are associated with the data set. Please cite this Ecology Data Paper if the data are used in publication and teaching events. © 2019 The Authors. Ecology © 2019 The Ecological Society of Americ

Software development for hepatocyte function quantification when using radioisotopic methods

Trabalho Final do Mestrado Integrado em Medicina apresentado à Faculdade de MedicinaIntrodução: Não existe um método que, isoladamente, seja fiável para a avaliação da função hepática, sendo frequente o uso da cintigrafia hepatobiliar ou medição dos níveis séricos de substâncias metabolizadas no fígado, para esse efeito. A cintigrafia hepática tem um valor acrescido de diagnóstico e prognóstico em patologias hepatobiliares, quando associada a uma análise funcional quantificada da função hepatocitária através da atividade do radiofármaco. Com esse objetivo, pretendeu-se implementar um programa computacional que permita uma análise funcional quantificada da função hepática, após seleção do método e modelos matemático mais adequados.Material e métodos: O método escolhido para modelar as curvas de atividade plasmática e hepática do radiofármaco, tem como base modelos compartimentais. A função da retenção hepática é obtida por desconvolução. Um programa computacional, associado a um interface user-friendly, foi desenvolvido no software Matlab Apps Designer. Resultados: O método proposto foi implementado, através de código, num programa computacional. Foi obtida uma interface que permite a um utilizador, sem conhecimentos de programação, aceder a informações qualitativas e quantitativas de dados cintigráficos hepatobiliares. Através da seleção de regiões de interesse, o programa permite obter diferentes curvas de atividade-tempo do radiofármaco. Os parâmetros quantificados apresentados pela interface do programa são a fração de extração hepatocitária, o tempo de semivida efetiva de excreção do radiofármaco, tempo médio de trânsito e tempo máximo de atividade hepática. A validação do programa foi realizada através do uso de dados cintigráficos armazenados em bases de dados, comparando alguns dos parâmetros quantificados obtidos neste trabalho com os valores obtidos por outros programas entretanto desatualizados.Discussão e conclusão: Os resultados obtidos mostram que o programa, em conjunto com a interface desenhada, funciona de acordo com os objetivos traçados. A prova de conceito do programa mostrou resultados que validam o trabalho desenvolvido. O método e o programa propostos são uma ferramenta de elevado valor na pesquisa de alterações da função hepática, para o uso em investigação ou na área médica e cirúrgica, quantificando numericamente os dados cintigráficos.Introduction: There is no isolated and reliable method for the assessment of liver function. Hepatobiliary scintigraphy and measurement of serum levels of substances metabolized in the liver are frequently used for this purpose. Liver scintigraphy has an additional diagnostic and prognostic value in hepatobiliary pathologies, when associated with a quantified functional analysis of the liver function through radiopharmaceutical activity. With this objective, a computer program was intended to be implemented that allows a quantified functional analysis of liver function, after research and choice of the most appropriated method and mathematical models.Material and methods: The method chosen to model the plasma and hepatic activity curves of the radiopharmaceutical is based on compartmental models. Liver retention function is obtained by deconvolution. A computer program, associated with a user-friendly interface, was developed using the Matlab Apps Designer software.Results: The proposed method was designed and implemented in a computer program. An interface that allows users, without programming knowledge, to access qualitative and quantitative information from hepatobiliary scintigraphic data, was obtained. Through the selection of regions of interest, the program allows to obtain different activity-time curves of the radiopharmaceutical. The quantified parameters presented by the interface are the hepatic extraction fraction, the effective half-life of radiopharmaceutical excretion, mean transit time and maximum time of hepatic activity. The validation of the program was carried out using scintigraphic data stored in databases, comparing some of the quantified parameters obtained in this work with the values obtained by other outdated programs.Discussion and conclusion: The obtained results show that the program, together with the designed interface, works according to the outlined objectives. The program proof of concept showed results that validate the developed work. The proposed method and program are a highly valuable tool in the investigation of changes in liver function, for use in research or in medical and surgical field, numerically quantifying the scintigraphic data

Evaluation of a quality improvement intervention to reduce anastomotic leak following right colectomy (EAGLE): pragmatic, batched stepped-wedge, cluster-randomized trial in 64 countries

Background Anastomotic leak affects 8 per cent of patients after right colectomy with a 10-fold increased risk of postoperative death. The EAGLE study aimed to develop and test whether an international, standardized quality improvement intervention could reduce anastomotic leaks. Methods The internationally intended protocol, iteratively co-developed by a multistage Delphi process, comprised an online educational module introducing risk stratification, an intraoperative checklist, and harmonized surgical techniques. Clusters (hospital teams) were randomized to one of three arms with varied sequences of intervention/data collection by a derived stepped-wedge batch design (at least 18 hospital teams per batch). Patients were blinded to the study allocation. Low- and middle-income country enrolment was encouraged. The primary outcome (assessed by intention to treat) was anastomotic leak rate, and subgroup analyses by module completion (at least 80 per cent of surgeons, high engagement; less than 50 per cent, low engagement) were preplanned. Results A total 355 hospital teams registered, with 332 from 64 countries (39.2 per cent low and middle income) included in the final analysis. The online modules were completed by half of the surgeons (2143 of 4411). The primary analysis included 3039 of the 3268 patients recruited (206 patients had no anastomosis and 23 were lost to follow-up), with anastomotic leaks arising before and after the intervention in 10.1 and 9.6 per cent respectively (adjusted OR 0.87, 95 per cent c.i. 0.59 to 1.30; P = 0.498). The proportion of surgeons completing the educational modules was an influence: the leak rate decreased from 12.2 per cent (61 of 500) before intervention to 5.1 per cent (24 of 473) after intervention in high-engagement centres (adjusted OR 0.36, 0.20 to 0.64; P < 0.001), but this was not observed in low-engagement hospitals (8.3 per cent (59 of 714) and 13.8 per cent (61 of 443) respectively; adjusted OR 2.09, 1.31 to 3.31). Conclusion Completion of globally available digital training by engaged teams can alter anastomotic leak rates. Registration number: NCT04270721 (http://www.clinicaltrials.gov)

Núcleos de Ensino da Unesp: artigos 2008

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq