Thesis (Ph. D.)--Duke University, 1994. / Vita. Includes bibliographical references (leaves 83-90).

by Charles H. Fine. / "October 1983." / Bibliography: p. 38-40.

by Charles H. Fine. / "October 1983." / Bibliography: leaf 57.

Nos recentes leilões de energia realizados no setor elétrico brasileiro, a energia térmica foi uma das principais vencedoras. Este trabalho avalia a possibilidade de reversão desta tendência, mantendo a trajetória anterior de uma matriz limpa e renovável. A maior parte da eletricidade brasileira tem sido proveniente de hidrelétricas. O plano energético oficial, com horizonte de 2030, elaborado para o Governo pela Empresa de Pesquisa Energética (EPE) dá ênfase à geração térmica, à gás natural, carvão e nuclear, como alternativa de complementação à geração hídrica. Neste estudo, em contraponto à proposta oficial, a geração eólica é analisada como opção de complementação, ao invés da energia térmica. A curva de aprendizado da tecnologia eólica, no Brasil e no mundo, é investigada e seu resultado evidencia o potencial de competitividade quando comparada a outras fontes, como térmicas nucleares, a gás e a carvão. A substituição do parque de expansão térmica pela eólica é simulada mediante a análise comparativa dos custos de capital, combustível, operação e manutenção, considerando a curva de aprendizado potencial. Os resultados da simulação, em termos de custo a valor presente das alternativas, indicam que a geração eólica pode se tornar atrativa, tendo como atrativo adicional a redução da emissão de gases de efeito estufa. Dificuldades e barreiras para a penetração da geração da energia eólica são avaliadas. Também é analisada a possibilidade do atendimento da demanda de energia no Brasil no contexto do cenário da estabilização populacional e do consumo, na década de 2040, mediante oferta de energia renovável, substancialmente hidro-eólica. / In the recent energy auctions held in the Brazilian electric sector, thermal power plants were the major winners. This study evaluates the possibility of reversing such trend, maintaining the previous path of a clean and renewable energy mix. Most of Brazil\'s electricity has been generated by hydropower. However the official energy plan, with the horizon of 2030, prepared for the Government by the Energy Research Company (EPE) gives emphasis to the thermal generation to natural gas, coal and nuclear energy as an alternative to hydropower generation complementation. In this study, in contrast to the official proposal, wind generation is considered as an option to complement, rather than the thermal energy. The learning curve of wind technology in Brazil and worldwide, is investigated and its result shows the potential of competitiveness compared to other sources such as nuclear thermal, gas and coal. The replacement of thermal based expansion by the wind is simulated, by a comparative analysis of capital costs, fuel, operation and maintenance, considering the potential learning. The simulation results in terms of present value cost of the alternatives indicate that wind generation can become attractive, with the added benefit of reduction in emission of greenhouse gases. Difficulties and barriers to the penetration of wind power generation are evaluated. The possibility of meeting the demand for energy in Brazil in the context of the scenario population and energy demand stabilization, in the 2040s, through renewable and sustainable energy sources, substantially hydro and wind, is also assessed.

INTRODUÇÃO: Este estudo analisou o impacto da experiência em prostatectomia radical robótica na curva inicial da prostatectomia laparoscópica através dos resultados perioperatórios e funcionais e oncológicos precoces de 110 pacientes com câncer de próstata. PACIENTES E MÉTODOS: 110 pacientes, selecionados aleatoriamente, foram submetidos a PRL por dois cirurgiões com experiência prévia em cirurgia minimamente invasiva e PRR, no Instituto do Câncer do Estado de São Paulo. Os dados foram coletados prospectivamente. Foi utilizada abordagem transperitoneal simulando a técnica robótica. RESULTADOS: Houve uma redução significativa no tempo operatório que diminuiu até o caso 40, quando atingiu um platô. O volume de sangramento mediano foi 250ml (variação 50-1000ml). Nenhum paciente foi transfundido. As complicações foram distribuídas uniformemente ao longo da casuística. A taxa de margens positivas foi de 28,2% (pT2: 20%, pT3: 43,6%), e não apresentou tendência a redução. 61,3% das margens foram apicais. A taxa de continência foi de 88% e atingiu um platô próximo a 95% após 75 casos. CONCLUSÃO: Esse estudo mostra que existem múltiplas curvas no processo de aprendizado da PRL. A curva mais curta foi para tempo operatório. A curva para margens cirúrgicas não foi completada e necessita de intervenção para melhora dos resultados principalmente relacionados a margem apical. A transição entre as técnicas de prostatectomia pode ser considerada segura baseada nas baixas taxas de complicações, ausência de complicações graves ou transfusões sanguíneas / INTRODUCTION: This study analyzed the impact of the experience with Robotic-Assisted Laparoscopic Prostatectomy (RALP) on the initial experience with Laparoscopic Radical Prostatectomy (LRP) by examining perioperative results and early outcomes of 110 patients. LRPs were performed by two robotic fellowship trained surgeons with daily practice in RALP. PATIENTS and METHODS: 110 LRP was used to treat aleatory selected patients. The patients were divided into 4 groups for prospective analyses. A transperitoneal approach that simulates the RALP technique was used. RESULTS: The median operative time was 163 minutes (110 - 240), and this time significantly decreased through case 40, when the time plateaued (p = 0.0007). The median blood loss was 250 ml. No patients required blood transfusion. There were no life-threatening complications or deaths. Minor complications were uniformly distributed along the serie (P= 0,6401). The overall positive surgical margins (PSM) rate was 28.2% (20% in pT2 and 43.6% in pT3). PSM was in the prostate apex in 61.3% of cases. At the 12-month follow-up, 88% of men were continent (0-1 pad). CONCLUSION: The present study shows that there are multiple learning curves for LRP. The shallowest learning curve was seen for the operative time. Surgeons transitioning between the RALP and LRP techniques were considered competent based on the low perioperative complication rate, absence of major complications, and lack of blood transfusions. This study shows that a learning curve still exists and that there are factors that must be considered by surgeons transitioning between the two techniques

Introdução: A curva de aprendizado em prostatectomia radical laparoscópica (PRL) pode variar de 10 a 150 procedimentos. Nesta fase, observa-se o maior número de complicações perioperatórias e conversões, além de resultados oncológicos e funcionais precários. Neste estudo, foram comparadas duas séries iniciais de PRL, realizadas pelos acessos transperitoneal (PRLT) e extraperitoneal (PRLE). Objetivos: Comparar os resultados obtidos com a realização da PRL pelos acessos transperitoneal e extraperitoneal durante a curva de aprendizado, avaliando-se os resultados perioperatórios, oncológicos e funcionais. Pacientes e métodos: Procedeuse a uma análise comparativa retrospectiva entre os dados das primeiras 40 PRLT realizadas no Hospital Getúlio Vargas de Pernambuco (grupo 1) e os dados das primeiras 40 PRLE realizadas no Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo (grupo 2). Resultados: Comparando-se as variáveis trans-operatórias dos grupos 1 e 2, observamos diferenças estatísticas na preservação dos feixes vásculonervosos (77,5% vs 90%; p=0,008), tempo cirúrgico total (175,0 min vs 267,6 min;p<0,001) e da perda sanguínea estimada (177,5 ml vs 292,4 ml; p<0,001). Duas complicações (5%) foram observadas no grupo 1 (sangramento e lesão retal) e quatro (10%) ocorreram no grupo 2 (sangramento-2, lesão retal e de bexiga). Conversão para procedimento aberto foi necessária em um caso em cada grupo (2,5%). No período pósoperatório, as principais diferenças estatisticamente significantes entre os grupos 1 e 2 foram observadas nas comparações do tempo de internamento, do tempo de uso de catéter uretral, no uso de opióides, na recorrência bioquímica, na taxa de continência urinária e no tempo médio de seguimento. Nenhuma diferença estatística foi observada na incidência de complicações precoces (17,5% vs 17,5%; p= 1,000), porém três complicações maiores foram observadas no grupo 1, levando ao óbito de um paciente neste grupo. Dentre as complicações pós-operatórias tardias, observou-se uma diferença estatística quando se comparou a taxa de complicações menores entre os grupos 1 e 2 (30% vs 15%; p=0,004). Na comparação dos resultados oncológicos entre os grupos 1 e 2, observou-se diferença estatística no número total de margens cirúrgicas positivas (MCP) (10,3% vs 32,5%; p=0,016) e no estadiamento patológico (pT2: 94,8% vs 70% e pT3: 5,2% vs 30%; p=0,005). Correlacionando-se o achado de MCP e estadiamento patológico, observou-se que a maioria das MCP no grupo 1 ocorreu no estadio pT2 (75%), ao passo que 77% das MCP no grupo 2 ocorreu no estadio pT3. Conclusões: O acesso transperitoneal mostrou-se mais eficiente que o acesso extraperitoneal para a realização da prostatectomia radical laparoscópica durante a curva de aprendizado, porém enfatizando que a taxa de complicações graves foi maior quando este acesso foi utilizado. / Introduction: The learning curve in laparoscopic radical prostatectomy (LRP) can vary from 10 to 150 procedures. This procedure can be done using the transperitoneal or the extraperitoneal approach. So far, there is no consensus about the best way to perform LRP, mainly during the initial phases of the LRP programs. Objectives: To analyze and compare the perioperative, oncological and functional results obtained with both approaches while performing LRP during the learning curve. Patients and Methods: Data of the first 40 transperitoneal LRP (Group 1) performed at Getúlio Vargas Hospital of Recife were compared with the first 40 extraperitoneal LRP (Group 2) performed at Clinics Hospital of State University of São Paulo. Results: On transoperative time, statistically significant difference were observed comparing groups 1 and 2 related to the preservation of the neurovascular bundles (77,5% x 90%; p=0,008), overall surgical time (175 min x 267,6 min; p<0,001) and estimated blood loss (177,5 ml x 292,4 ml; p<0,001). Two complications (5%) were observed in group 1 (bleeding and rectal injury), whereas four (10%) were seen in group 2 (bleeding- 5%, rectal and bladder injury). Open conversion occurred in one case (2,5%) in both groups. On postoperative time, statistical difference comparing the groups 1 and 2 were seen in the in-hospital time, indwelling catheter time, narcotic use, biochemical recurrence and mean follow-up time. No statistical difference was observed related to the incidence of early complications (17,5% vs 17,5%; p= 1,000), but three major complications occurred in group 1, leading to one death in this group. On late postoperative time, a statistical difference was observed in the incidence of minor complications (30% vs 15%; p=0,004). Comparing the oncological results between groups 1 and 2, statistical difference was observed in the incidence of positive surgical margins (10,3% vs 32,5%; p=0,016) and pathological stages (pT2: 94,8% vs 70% and pT3: 5,2% vs 30%; p=0,005). The majority of positive margins in group 1 occurred in pT2 (75%), while this observation was more prevalent in pT3 (77%) in group 2. Conclusions: The transperitoneal approach was more efficient than the extraperitoneal approach for performing laparoscopic radical prostatectomy during the learning curve, but major complications were commoner when this approach was adopted.

The presence of learning in organizations is important for success and survival. Recent research into open source software developers has primarily suggested a social constructivist view where knowledge is constructed in the social relationships within the team culture. I report results from a case study that investigated the presence of situated learning among open source developers at an earlier time of a project. Thirty-eight developers were systematically selected and examined on their performance, experience and roles during ten months of maintenance work. I followed a model of learning curve effects that associated the improvement in the average resolving time with the accumulated experience. I found a strong relationship between the two variables and confirmed the presence of learning. In addition, I found a less convincing evidence to affirm knowledge depreciated among open source software developers. The depreciation factor was estimated to be 94 percent, compared to other studies which ranged between 65 to 85 percent. An additional investigation was conducted around the organization structure to understand whether core and peripheral members have different average resolving time. The finding was inconclusive to claim both groups have different means towards issue resolution. The consistency in the result of this thesis and several other related research efforts suggests that learning is likely to be an intrinsic characteristic of open source software development rather than just a speculation in the literatures.

Master of Science

To impede the progress of climate change, many policy makers are considering avenues to decarbonize electricity production. In addition to decarbonization, policy makers must consider how the cost of electricity will impact various stakeholders, balancing cost and social benefits. Offshore wind farms have the potential to produce affordable, carbon-free electricity, but they are a relatively new technology. The relative juvenescence of offshore wind lends itself to an uncertain future, regarding production costs. In this thesis, we seek to understand cost drivers behind offshore wind electricity by analyzing historic trends in offshore wind levelized cost of electricity (LCOE) through learning curves, characterizing how learning from producing a technology can lead to decreases in production costs. Additionally, we explore how the maturity of component technologies can affect the learning rate, and consequently the benefits of learning, of offshore wind. Finally, we create a robust data set to inform decision makers and researchers by marrying historic data to forward-looking expert elicitations.

Introduction: The main goal of our work was to compare the diagnostic accuracy of ultrasound examination and magnetic resonance imaging (MRI) in the assessment of deep endometriosis in the pelvis. Our second aim was to establish a learning curve of a sonographer and a radiologists (non-experts). As an introduction to the subject we have published 3 reviews on the diagnosis and one narrative review on the classification systems in the evaluation of endometriosis has been submitted for publication. Methodology: Reviews were written as narrative reviews based on PubMed search and scientific societies recommendations. We have offered participation to all patients in the endometriosis centre with high suspicion of deep endometriosis, who then underwent examination by ultrasound and MRI by expert and non-expert before their surgical treatment, all findings described according to the consensus IDEA (international Deep Endometriosis Analysis group, 2016). Surgical and histological findings were used as a reference standard. Learning curve was defined as an improvement in accuracy in three blocks, into which the patients were assigned in the chronological order. Results of the scientific studies: From 07/2016 to 02/2018 the participation was offered to 111 patients, 51 underwent both imaging examinations...