New Technology and Techniques for Needle-Based Magnetic Resonance Image-Guided Prostate Focal Therapy

The most common diagnosis of prostate cancer is that of localized disease, and unfortunately the optimal type of treatment for these men is not yet certain. Magnetic resonance image (MRI)-guided focal laser ablation (FLA) therapy is a promising potential treatment option for select men with localized prostate cancer, and may result in fewer side effects than whole-gland therapies, while still achieving oncologic control. The objective of this thesis was to develop methods of accurately guiding needles to the prostate within the bore of a clinical MRI scanner for MRI-guided FLA therapy. To achieve this goal, a mechatronic needle guidance system was developed. The system enables precise targeting of prostate tumours through angulated trajectories and insertion of needles with the patient in the bore of a clinical MRI scanner. After confirming sufficient accuracy in phantoms, and good MRI-compatibility, the system was used to guide needles for MRI-guided FLA therapy in eight patients. Results from this case series demonstrated an improvement in needle guidance time and ease of needle delivery compared to conventional approaches. Methods of more reliable treatment planning were sought, leading to the development of a systematic treatment planning method, and Monte Carlo simulations of needle placement uncertainty. The result was an estimate of the maximum size of focal target that can be confidently ablated using the mechatronic needle guidance system, leading to better guidelines for patient eligibility. These results also quantified the benefit that could be gained with improved techniques for needle guidance

MSS D Multispectral Scanner System

The development and acceptance testing of the 4-band Multispectral Scanners to be flown on LANDSAT D and LANDSAT D Earth resources satellites are summarized. Emphasis is placed on the acceptance test phase of the program. Test history and acceptance test algorithms are discussed. Trend data of all the key performance parameters are included and discussed separately for each of the two multispectral scanner instruments. Anomalies encountered and their resolutions are included

Sixth Aerospace Mechanisms Symposium

Design and development of mechanisms for spacecraft components - conference

NASA Tech Briefs, April 2010

Topics covered include: Active and Passive Hybrid Sensor; Quick-Response Thermal Actuator for Use as a Heat Switch; System for Hydrogen Sensing; Method for Detecting Perlite Compaction in Large Cryogenic Tanks; Using Thin-Film Thermometers as Heaters in Thermal Control Applications; Directional Spherical Cherenkov Detector; AlGaN Ultraviolet Detectors for Dual-Band UV Detection; K-Band Traveling-Wave Tube Amplifier; Simplified Load-Following Control for a Fuel Cell System; Modified Phase-meter for a Heterodyne Laser Interferometer; Loosely Coupled GPS-Aided Inertial Navigation System for Range Safety; Sideband-Separating, Millimeter-Wave Heterodyne Receiver; Coaxial Propellant Injectors With Faceplate Annulus Control; Adaptable Diffraction Gratings With Wavefront Transformation; Optimizing a Laser Process for Making Carbon Nanotubes; Thermogravimetric Analysis of Single-Wall Carbon Nanotubes; Robotic Arm Comprising Two Bending Segments; Magnetostrictive Brake; Low-Friction, Low-Profile, High-Moment Two-Axis Joint; Foil Gas Thrust Bearings for High-Speed Turbomachinery; Miniature Multi-Axis Mechanism for Hand Controllers; Digitally Enhanced Heterodyne Interferometry; Focusing Light Beams To Improve Atomic-Vapor Optical Buffers; Landmark Detection in Orbital Images Using Salience Histograms; Efficient Bit-to-Symbol Likelihood Mappings; Capacity Maximizing Constellations; Natural-Language Parser for PBEM; Policy Process Editor for P(sup 3)BM Software; A Quality System Database; Trajectory Optimization: OTIS 4; and Computer Software Configuration Item-Specific Flight Software Image Transfer Script Generator

Doctor of Philosophy

dissertationIn this dissertation, we present methods for intuitive telemanipulation of manipulators that use piezoelectric stick-slip actuators (PSSAs). Commercial micro/nano-manipulators, which utilize PSSAs to achieve high precision over a large workspace, are typically controlled by a human operator at the joint level, leading to unintuitive and time-consuming telemanipulation. Prior work has considered the use of computer-vision-feedback to close a control loop for improved performance, but computer-vision-feedback is not a viable option for many end users. We discuss how open-loop models of the micro/nano-manipulator can be used to achieve desired end-effector movements, and we explain the process of obtaining open-loop models. We propose a rate-control telemanipulation method that utilizes the obtained model, and we experimentally quantify the effectiveness of the method using a common commercial manipulator (the Kleindiek MM3A). The utility of open-loop control methods for PSSAs with a human in the loop depends directly on the accuracy of the open-loop models of the manipulator. Prior research has shown that modeling of piezoelectric actuators is not a trivial task as they are known to suffer from nonlinearities that degrade their performance. We study the effect of static (non-inertial) loads on a prismatic and a rotary PSSA, and obtain a model relating the step size of the actuator to the load. The actuator-specific parameters of the model are calibrated by taking measurements in specific configurations of the manipulator. Results comparing the obtained model to experimental data are presented. PSSAs have properties that make them desirable over traditional DC-motor actuators for use in retinal surgery. We present a telemanipulation system for retinal surgery that uses a full range of existing disposable instruments. The system uses a PSSA-based manipulator that is compact and light enough that it could reasonably be made head-mounted to passively compensate for head movements. Two mechanisms are presented that enable the system to use existing disposable actuated instruments, and an instrument adapter enables quick-change of instruments during surgery. A custom stylus for a haptic interface enables intuitive and ergonomic telemanipulation of actuated instruments. Experimental results with a force-sensitive phantom eye show that telemanipulated surgery results in reduced forces on the retina compared to manual surgery, and training with the system results in improved performance. Finally, we evaluate operator efficiency with different haptic-interface kinematics for telemanipulated retinal surgery. Surgical procedures of the retina require precise manipulation of instruments inserted through trocars in the sclera. Telemanipulated robotic systems have been developed to improve retinal surgery, but there is not a unique mapping of the motions of the surgeon's hand to the lower-dimensional motions of the instrument through the trocar. We study operator performance during a precision positioning task on a force-sensing phantom retina, reminiscent of telemanipulated retinal surgery, with three common haptic-interface kinematics implemented in software on a PHANTOM Premium 6DOF haptic interface. Results from a study with 12 human subjects show that overall performance is best with the kinematics that represent a compact and inexpensive option, and that subjects' subjective preference agrees with the objective performance results

A gas flow indicator for portable life support systems

A three-part program was conducted to develop a gas flow indicator (GFI) to monitor ventilation flow in a portable life support system. The first program phase identified concepts which could potentially meet the GFI requirements. In the second phase, a working breadboard GFI, based on the concept of a pressure sensing diaphragm-aneroid assembly connected to a venturi, was constructed and tested. Extensive testing of the breadboard GFI indicated that the design would meet all NASA requirements including eliminating problems experienced with the ventilation flow sensor used in the Apollo program. In the third program phase, an optimized GFI was designed by utilizing test data obtained on the breadboard unit. A prototype unit was constructed using prototype materials and fabrication techniques, and performance tests indicated that the prototype GFI met or exceeded all requirements

Postmodernism: Style and Subversion 1970-1990

‘Postmodernism’ was the final instalment of a 12-year series of V&A exhibitions exploring 20th-century design. It examined a diverse collection of creative practices in art, architecture, design, fashion, graphics, film, performance and pop music/video, which the curators, Pavitt and Adamson (V&A/RCA), identified under the common theme of ‘postmodernism’. The exhibition assessed the rise and decline of postmodern strategies in art and style cultures of the period, exploring their radical impact as well as their inextricable links with the economics and effects of late-capitalist culture. The exhibition comprised over 250 objects, including large-scale reconstructions and archive film/video footage, drawn from across Europe, Japan and the USA. It was the first exhibition to bring together this range of material and to foreground the significance of pop music and performance in the development of postmodernism. Pavitt originated and co-curated the exhibition with Adamson. They shared intellectual ownership of the project and equal responsibility for writing and editing the accompanying 320-page book (including a 40,000-word jointly written introduction), but divided research responsibilities according to geography and subject. The research was conducted over four years, with Pavitt leading on European and British material. This involved interviewing artists, designers and architects active in the period and working with collections and archives across Europe. The research led to the acquisition of c.80 objects for the V&A’s permanent collections, making it one of the most significant public collections of late-20th-century design in the world. The exhibition was critically reviewed worldwide. For the Independent, ‘bright ideas abound at the V&A’s lucid show’ (2011). It attracted 115,000 visitors at the V&A (15% over the Museum’s target) and travelled in 2012 to MART Rovereto, Italy (50,000 visitors) and Landesmuseum Zürich, Switzerland (70,000 visitors). Pavitt was invited to speak about the exhibition in the UK, USA, Poland, Portugal, Ireland and Italy (2010-12)