7 research outputs found
The contribution of multi-sensory aids to a meaningful art program.
Thesis (Ed.M.)--Boston Universit
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Stiffness Analysis of the Tethered Coulomb Structure Concept and Application
This thesis investigates the Tethered Coulomb Structure (TCS) concept and its operating regime for creating large space structures and for providing satellite situational awareness. A TCS consists of a three-dimensional tethered spacecraft formation that uses electrostatic forces to repel the spacecraft and inflate the formation to a semi-rigid structure. The influential force modeling and equations of motion are given. Numerical simulations of a two-node TCS show that TCS systems have the greatest translational and rotational stiffness when the nodes have high voltage, low separation distance and low mass. Single tether two node TCS at 30 kV with 5 m separation are shown to withstand up to 50 deg/min initial rotations before reaching an entangled state. Multiple tether TCS simulations demonstrate that additional tethers between TCS nodes provides full three-dimensional stiffness and reduces the maximum absolute rotation for the system due to an initial perturbation. Using a double- or triple-tether TCS increases the maximum allowable initial rotation by 40-60%. Orbital perturbations, differential gravity and solar radiation pressure, are examined and it is demonstrated that both can be considered negligible for this study. A TCS configuration where one small spacecraft is tethered to a large spacecraft in orbit is presented. Simulations using a simple attitude control law show that a TCS in this configuration can be used to hold the smaller craft at a relatively fixed arbitrary position and rotation relative to the larger craft. Using multiple tethers for this configuration allows for separation distances of up to 10 m with less than 5 deg and 1 cm relative rotation and translation, respectively
Power, potential, and pitfalls in global health academic partnerships: review and reflections on an approach in Nepal
ABSTRACT Background:: Global health academic partnerships are centered around a core tension: they often mirror or reproduce the very cross-national inequities they seek to alleviate. On the one hand, they risk worsening power dynamics that perpetuate health disparities; on the other, they form an essential response to the need for healthcare resources to reach marginalized populations across the globe. Objectives:: This study characterizes the broader landscape of global health academic partnerships, including challenges to developing ethical, equitable, and sustainable models. It then lays out guiding principles of the specific partnership approach, and considers how lessons learned might be applied in other resource-limited settings. Methods:: The experience of a partnership between the Ministry of Health in Nepal, the non-profit healthcare provider Possible, and the Health Equity Action and Leadership Initiative at the University of California, San Francisco School of Medicine was reviewed. The quality and effectiveness of the partnership was assessed using the Tropical Health and Education Trust Principles of Partnership framework. Results:: Various strategies can be taken by partnerships to better align the perspectives of patients and public sector providers with those of expatriate physicians. Actions can also be taken to bring greater equity to the wealth and power gaps inherent within global health academic partnerships. Conclusions:: This study provides recommendations gleaned from the analysis, with an aim towards both future refinement of the partnership and broader applications of its lessons and principles. It specifically highlights the importance of targeted engagements with academic medical centers and the need for efficient organizational work-flow practices. It considers how to both prioritize national and host institution goals, and meet the career development needs of global health clinicians