Zero-error source-channel coding with entanglement.

We study the use of quantum entanglement in the zero-error source-channel coding problem. Here, Alice and Bob are connected by a noisy classical one-way channel, and are given correlated inputs from a random source. Their goal is for Bob to learn Alice's input while using the channel as little as possible. In the zero-error regime, the optimal rates of source codes and channel codes are given by graph parameters known as the Witsenhausen rate and Shannon capacity, respectively. The Lov\'asz theta number, a graph parameter defined by a semidefinite program, gives the best efficiently-computable upper bound on the Shannon capacity and it also upper bounds its entanglement-assisted counterpart. At the same time it was recently shown that the Shannon capacity can be increased if Alice and Bob may use entanglement. Here we partially extend these results to the source-coding problem and to the more general source-channel coding problem. We prove a lower bound on the rate of entanglement-assisted source-codes in terms Szegedy's number (a strengthening of the theta number). This result implies that the theta number lower bounds the entangled variant of the Witsenhausen rate. We also show that entanglement can allow for an unbounded improvement of the asymptotic rate of both classical source codes and classical source-channel codes. Our separation results use low-degree polynomials due to Barrington, Beigel and Rudich, Hadamard matrices due to Xia and Liu and a new application of the quantum teleportation scheme of Bennett et al

Burnout e a empatia médico-doente

Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2015Contexto: Burnout designa a síndroma de exaustão mental resultante da exposição a factores stressores crónicos relacionados com o trabalho. A prevalência da síndroma em médicos e a possibilidade desta deteriorar a empatia clínica, fundamental no sucesso terapêutico da intervenção médica, evidenciam a importância deste tema. Objectivos: Comparar os níveis de burnout e de empatia numa amostra de médicos portugueses internos e especialistas, investigando que características sociodemográficas e laborais influenciam esses níveis. Métodos: Estudo exploratório de uma amostra de conveniência de 104 médicos que trabalham em instituições da grande Lisboa, usando um questionário que inclui a escala MBI e a de empatia de Jefferson. Resultados: A prevalência de burnout na amostra é de 15,4%. Nesta amostra, 25%, 26% e 23% dos médicos apresentaram pontuação alta para EE, DP e PRP respectivamente. Os internos apresentaram níveis superiores de EE (p=0,034), DP (p=0,005) e PRP (p=0,002) e níveis de empatia inferiores (p=0,048) aos dos especialistas. Os internos têm maior carga horária semanal (p=0,017) apresentam maior tendência para trabalhar no SU (p=0,00) e ter exclusividade no SNS (p=0,00). Os profissionais que têm filhos, apresentam níveis inferiores nas de EE, DP e PRP. Verificou-se que duas variáveis são preditoras significativas de burnout: as horas semanais de trabalho e a satisfação com a carreira médica, que explicam 32,8% da variação da EE. A satisfação com a carreira explica 13,6% da PRP. Identificaram-se dois preditores negativos significativos de empatia do médico: a DP (p=0,027) e a PRP (p=0,00), que explicam 28,4% da variação de empatia. Conclusões: Os resultados deste trabalho apontam para a necessidade das instituições se focarem no bem-estar dos médicos, pelo impacto negativo que a síndroma tem na empatia e consequentes implicações na qualidade e sucesso terapêutico. As intervenções de prevenção do burnout devem ser a nível individual e organizacional, com a melhoria das condições de trabalho dos médicos através por exemplo da diminuição da carga horária, e que sejam motivo de maior satisfação com a carreira médica. A síndroma deve ser objecto de futuros estudos que permitirão identificar factores de risco específicos para burnout, bem como de meios de prevenção e intervenção mais eficazes nos profissionais de saúde.Background: Burnout is known as the mental exaustion syndrome related to the chronic exposition to job stress factors. Its prevalence in physicians and the possibility that it can deteriorate clinical empathy, essential for a well-succeed medical intervention, are the reasons why this theme is important. Objectives: The aim of this study is to compare the levels of burnout and empathy in a sample of portuguese residents and specialists, and to research which sociodemographical and laboral characteristics may influence these two variables. Methods: It is an exploratory study consisting of a convenience sample with 104 physicians working in institutions located in the region of Lisbon, using a questionnaire containing the Maslach Burnout Inventory and the Jefferson scale of empathy. Results: In our sample, 15,4% physicians are in burnout. 25%, 26% e 23% of the physicians scored high for EE, DP and LPA respectively. Residents have higher scores for EE (p=0,034), DP (p=0,005) and PRP (p=0,002) and a lower level of empathy (p=0,048) compared to specialists. Residents work more hours per week (p=0,017), and have more tendency to work in the ER and to have exclusivity in public health service. Physicians with children have lower EE, DP and LPA. Also two variables are predictive factors for burnout: workload per week and satisfaction with medical career, which explain 32,8% of physician EE variation. Satisfaction with career explains 13,6% of PRP variation. Two negative predictive factors for empathy were identified: DP (p=0,027) and LPA (p=0,00), both explain 28,4% of physician empathy variation. Conclusions: Our results prove the need of health institutions to focus on physicians’ well-being, as burnout has an negative impact on empathy and consequently on the quality and success of therapeutic intervention. Preventive interventions for burnout must be individual and organizational in improving working conditions, for example with the reduction of workload per week, in a way that physicians feel more satisfacted with their career. Burnout must be object of future trials which will help to identify specific risk factors for burnout as well as preventive and more effective interventions for health workers