Sistema para gestão remota de redes experimentais

Mestrado em Engenharia de Computadores e TelemáticaA Internet e as redes no seu geral estão cada vez mais presentes no nosso quotidiano. No entanto, o seu crescente uso destaca também algumas das suas limitações, levando os investigadores de redes a criarem novas soluções, numa tentativa de preverem e resolverem problemas que daí possam advir. O desenvolvimento destas soluções implica que sejam realizados testes exaustivos antes que estas se tornem aptas para o uso das massas. Podem ser adoptadas diversas abordagens para a realização destes testes. Simulações são importantes como uma primeira aproximação, contudo, não conseguem captar a dinâmica e a imprevisibilidade de um ambiente real. A emulação surge como alternativa, tentando colmatar essa falha, no entanto, não é eficaz na reprodução de cenários mais complexos. A solução poderá passar pela criação de infra-estruturas dedicadas ao teste destas soluções, denominadas de redes experimentais, permitindo realizar uma avaliação mais profunda e fiável das mesmas. Contudo a sua construção envolve grandes custos e as infra-estruturas caem em desuso assim que é alcançado o produto final. É necessário desenvolver maneiras de instrumentalizar estas infra-estruturas, de forma a optimizar estes recursos para futuros testes. Esta dissertação centra-se nos problema evidenciados na criação destas redes de teste, estudando as existentes formas de gestão destas redes experimentais, bem como o seu uso optimizado com vista à criação de experiencias. Pretende-se assim desenvolver no âmbito desta tese, uma ferramenta que permita aos utilizadores criarem e usarem facilmente e de forma eficiente uma rede experimental.The Internet, as with networks in general, is increasingly present in our everyday lives. However, its use also highlights some of their limitations, leading researchers to create new network solutions in an attempt to anticipate and solve problems that may arise. These solutions require exhaustive tests before they become eligible for production. Several approaches can be taken to conduct such tests. Simulations are important as first approximations; however, they fail to capture the dynamics and unpredictability of a real environment. Emulations present an alternative, but fail to reproduce more complex scenarios. Experimentation facilities must therefore be deployed, to achieve a higher level of realism. These facilities, also referred as testbeds, involve high-complexity deployment and operation, falling into disuse once they arrive at a final product. Methods of managing these infrastructures must be developed in order to avoid this waste of resources for future tests. This dissertation focuses on the problems inherent to the management of these facilities, with a focus on their users. Different approaches in network testing must be studied and the different methodologies on experimentation must be collected. An application is developed to address this problem, enabling users to create their experiments and collect results in both an organized and effective manner

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)