Resumo Objetivo Descrever as mudanças nos estilos de vida, quanto ao consumo de tabaco, bebidas alcoólicas, alimentação e atividade física, no período de restrição social consequente à pandemia da COVID-19. Métodos Estudo transversal realizado com dados do inquérito ConVid sobre comportamentos em saúde. Os dados foram coletados por meio de questionário on-line autopreenchido pelos participantes. Procedimentos de pós-estratificação foram empregados para o cálculo das prevalências e intervalos de confiança de 95%. Resultados Participaram 45.161 indivíduos com 18 ou mais anos de idade. Durante o período de restrição social, foi relatada diminuição da prática de atividade física e aumento do tempo em frente a telas, da ingestão de alimentos ultraprocessados, do número de cigarros fumados e do consumo de bebidas alcóolicas. Foram observadas diferenças segundo sexo e faixa etária. Conclusão Os resultados apontam uma piora dos estilos de vida e aumento de comportamentos de risco à saúde.

Refactoring is a widespread practice that helps developers to improve the maintainability and readability of their code. However, there is a limited number of studies empirically investigating the actual motivations behind specific refactoring operations applied by developers. To fill this gap, we monitored Java projects hosted on GitHub to detect recently applied refactorings, and asked the developers to explain the reasons behind their decision to refactor the code. By applying thematic analysis on the collected responses, we compiled a catalogue of 44 distinct motivations for 12 well-known refactoring types. We found that refactoring activity is mainly driven by changes in the requirements and much less by code smells. Extract Method is the most versatile refactoring operation serving 11 different purposes. Finally, we found evidence that the IDE used by the developers affects the adoption of automated refactoring tools.

This dissertation studies a family of the state-of-the-art PNC schemes called compute-and-forward (C&F). C&F was originally proposed and studied from an information-theoretic perspective. As such, it typically relies on several strong assumptions: very long block length, almost unbounded complexity, perfect channel state information, and no decoding errors at the relays; its benefit is often analyzed for simple network configurations. The aim of this dissertation is two-fold: first, to relax the above assumptions while preserving the performance of C&F, and second, to understand the benefit of C&F in more realistic network scenarios, such as random-access wireless networks.There are four main results in this dissertation. First, an algebraic framework is developed, which establishes a direct connection between C&F and module theory. This connection allows us to systematically design lattice codes for C&F with controlled block length and complexity. In particular, explicit design criteria are derived, concrete design examples are provided, and it is shown that nominal coding gains from 3 to 7.5 dB can be obtained with relatively short block length and reasonable decoding complexity. Second, a new C&F scheme is proposed, which, unlike conventional C&F schemes, does not require any channel state information (CSI). It is shown that this CSI-free scheme achieves, for a certain class of lattice codes, almost the same throughput as its CSI-enabled counterpart. Third, an end-to-end error control mechanism is designed, which effectively mitigates decoding errors introduced at wireless relays. In particular, the end-to-end error control problem is modeled as a finite-ring matrix channel problem, for which tight capacity bounds and capacity-approaching schemes are provided. The final part of this dissertation studies the benefit of C&F in random-access wireless networks. In particular, it is shown that C&F significantly improves the network throughput and delay performance of slotted-ALOHA-based random-access protocols.ii Acknowledgements This thesis is the result of the support, help, and advice that I have received from an amazing group of scholars and students at the University of Toronto. Without them this dissertation wouldn't have been possible. First, I feel very fortunate to have two great supervisors: Prof. Frank R. Kschischang and Prof.Baochun Li. As an advisor, Frank has consistently exceeded my expectation. He is not only a brilliant researcher and excellent teacher, but also truly a kind and caring person. He has given me a tremendous amount in the past six years, I can only thank him for a subset. In particular, I have benefited greatly from his focus on fundamental problems, his taste for beautiful mathematics, his emphasis on clarity and grace, and his dedication in developing his students to their full potential. I am very grateful to Frank for making my PhD journey so exciting and rewarding! Frank also has a great sense of humor.I will always remember how much fun we had together during our endless discus...

Resumo Objetivo: Analisar a frequência de tristeza, nervosismo e alterações do sono durante a pandemia de COVID-19 no Brasil, identificando os segmentos demográficos mais afetados. Métodos: Estudo transversal, com questionário aplicado via web a adultos e idosos, coletando informações sobre condições de vida, saúde e comportamento. Foram estimadas prevalências e razões de prevalências ajustadas por idade e sexo. Resultados: De 45.161 brasileiros respondentes, verificou-se que, durante a pandemia, 40,4% (IC95% 39,0;41,8) se sentiram frequentemente tristes ou deprimidos, e 52,6% (IC95% 51,2;54,1) frequentemente ansiosos ou nervosos; 43,5% (IC95% 41,8;45,3) relataram início de problemas de sono, e 48,0% (IC95% 45,6;50,5) problema de sono preexistente agravado. Tristeza, nervosismo frequentes e alterações do sono estiveram mais presentes entre adultos jovens, mulheres e pessoas com antecedente de depressão. Conclusão: As elevadas prevalências encontradas indicam a necessidade de garantir a provisão de serviços de atenção à saúde mental e à qualidade do sono, adaptados ao contexto pandêmico.

The problem of designing new physical-layer network coding (PNC) schemes via lattice partitions is considered. Building on a recent work by Nazer and Gastpar, who demonstrated its asymptotic gain using information-theoretic tools, we take an algebraic approach to show its potential in non-asymptotic settings. We first relate Nazer-Gastpar's approach to the fundamental theorem of finitely generated modules over a principle ideal domain. Based on this connection, we generalize their code construction and simplify their encoding and decoding methods. This not only provides a transparent understanding of their approach, but more importantly, it opens up the opportunity to design efficient and practical PNC schemes. Finally, we apply our framework for PNC to a Gaussian relay network and demonstrate its advantage over conventional PNC schemes.Comment: 5 pages, 3 figures, accepted to IEEE Int. Symp. Information Theory, 201