Searching for the Transatlantic Freedom: The Art of Valerie Maynard

This thesis focuses on an African-American female artist, Valerie Maynard, examining how she synthesizes African and American elements in her works. It provides detailed formal and iconographical analyses, revealing concealed meanings and paying special attention to those works with which the artist mirrors the Black experience in the United States and Africa on the other side of the Atlantic. In the process, the thesis sheds new light on the significance of Valerie Maynard\u27s work and how she has used some of them to embody the Black quest for freedom and social justice during the Civil Rights struggle of the 1960s and 1970s and beyond

Thermal phenomena and power balance in a helicon plasma

textThis work is motivated by the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) experiment. This device uses a helicon antenna to generate a plasma inside a dielectric tube, which is radially confined and directed towards the rocket nozzle by an axial magnetic field. An ion cyclotron heating antenna further heats the ions, and a magnetic nozzle accelerates the plasma along the confining magnetic field as it leaves the rocket, ultimately allowing it to detach from the magnetic field and produce thrust. The experimental research presented here provides insight into the physical mechanisms of power flow in a helicon system by providing an overall system power balance in the form of heat flux measurements, and exploring changes in the heat fluxes in different parts of the system in response to varying operational parameters. An infrared (IR) camera measures the total heat flux into the dielectric tube surface, and axially scanned bolometer and UV photodiode probes measure the radial power loss from particles and radiation. Results from IR camera measurements on three different helicon systems are presented: the VASIMR VX-50 experiment, the VASIMR VX-CR experiment, and the University of Texas at Austin (UT) helicon experiment. These results demonstrate the development of the IR camera diagnostic for use on helicon systems of varying scale and geometry, and show reasonable agreement as to the fraction of input power lost to the dielectric tube walls. On the UT experiment, the results presented account for essentially all of the input power, providing a full system power balance. The data from all three experiments indicate that radial transport of ions to the interior wall is the dominant mechanism of power loss, with UV radiation contributing a small percentage. Additional experiments on the UT helicon explore energy and particle transport to the wall due to capacitive coupling of ions near the antenna. These experiments show clear damage to the dielectric tube surface directly under the antenna, due to physical plasma etching of the surface by bombarding ions that are accelerated into the wall by local electric fields from the antenna.Aerospace Engineerin

Spectral Profiler Probe for In Situ Snow Grain Size and Composition Stratigraphy

An ultimate goal of the climate change, snow science, and hydrology communities is to measure snow water equivalent (SWE) from satellite measurements. Seasonal SWE is highly sensitive to climate change and provides fresh water for much of the world population. Snowmelt from mountainous regions represents the dominant water source for 60 million people in the United States and over one billion people globally. Determination of snow grain sizes comprising mountain snowpack is critical for predicting snow meltwater runoff, understanding physical properties and radiation balance, and providing necessary input for interpreting satellite measurements. Both microwave emission and radar backscatter from the snow are dominated by the snow grain size stratigraphy. As a result, retrieval algorithms for measuring snow water equivalents from orbiting satellites is largely hindered by inadequate knowledge of grain size

Identification of the Sex Pheromone of the Webbing Coneworm Moth, Dioryctria disclusa (Lepidoptera: Pyralidae)

A sex pheromone component for the webbing coneworm, Dioryctria disclusa, has been identified as (Z)-9-tetradecenyl acetate. Traps baited with rubber septa impregnated with this compound at loadings of 30 to 300 μg caught the same as or significantly better than traps baited with two virgin female moths. Addition of 3 to 30% of the E isomer did not increase trap catch, and only (Z)-9-tetradecenyl acetate was found in the female extrac

Positive-Buoyancy Rover for Under Ice Mobility

A buoyant rover has been developed to traverse the underside of ice-covered lakes and seas. The rover operates at the ice/water interface and permits direct observation and measurement of processes affecting freeze- over and thaw events in lake and marine environments. Operating along the 2- D ice-water interface simplifies many aspects of underwater exploration, especially when compared to submersibles, which have difficulty in station-keeping and precision mobility. The buoyant rover consists of an all aluminum body with two aluminum sawtooth wheels. The two independent body segments are sandwiched between four actuators that permit isolation of wheel movement from movement of the central tether spool. For normal operations, the wheels move while the tether spool feeds out line and the cameras on each segment maintain a user-controlled fixed position. Typically one camera targets the ice/water interface and one camera looks down to the lake floor to identify seep sources. Each wheel can be operated independently for precision turning and adjustments. The rover is controlled by a touch- tablet interface and wireless goggles enable real-time viewing of video streamed from the rover cameras. The buoyant rover was successfully deployed and tested during an October 2012 field campaign to investigate methane trapped in ice in lakes along the North Slope of Alaska

The evolution of mating systems in bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae)

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72492/1/j.1096-3642.1983.tb00858.x.pd