Designing a high-efficiency hydrostatic bicycle transmission

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.Includes bibliographical references (leaf 24).Hydrostatic bicycle drives use a working fluid instead of the common roller-chain to transmit power to the drive wheel. These transmissions are typically considered too inefficient for human power applications. An experiment consisting of a very simple hydrostatic drive was designed and built in an attempt to measure the efficiency of these devices at approximate cycling speeds. A theoretical model was also developed to help predict losses using a wider range of operational parameters. Due to shortcomings of the experiment design, the measured efficiencies were on the order of 60% - considerably lower than those theoretically possible. Although the experimental results are of limited value, this study highlights the importance of minimizing side-loading on hydraulic cylinder piston-rods during low-speed, low-pressure operation. The research is used to suggest several design features which may aid in continued attempts to develop a highly efficient hydrostatic transmission.by Michael T. SocksS.B

The "Statinth" wonder of the world: a panacea for all illnesses or a bubble about to burst

After the introduction of statins in the market as effective lipid lowering agents, they were shown to have effects other than lipid lowering. These actions were collectively referred to as 'pleiotropic actions of statins.' Pleiotropism of statins formed the basis for evaluating statins for several indications other than lipid lowering. Evidence both in favour and against is available for several of these indications. The current review attempts to critically summarise the available data for each of these indications

Staff nurse views of important aspects of nursing practice

The purpose of this study was to identify what registered nurses employed in hospitals perceived to be important to their nursing practice. Staff nurse opinions were analyzed to explore similarities and differences between demonstration and comparison sits, and demonstration sties over time, during early implementation of the Differentiated Group Professional Practice (DGPP) model. An exploratory/descriptive design was used to analyze the content of written responses to one open-ended question. Nurses on the demonstration units expressed fewer responses related to administrative and nursing management support and more responses related to lack of recognition from nursing management, continuing education, pay related to responsibility, non-nursing tasks, and group cohesion. Results supported the conceptual framework of the DGPP model. Additional categories revealed by the analysis included administration, education, interdepartmental communication, job alternatives, nursing management, physical environment, and staffing