Mercury (Hg) has been recognized as a contaminant of global concern due to its high toxicity, as well as its ability to mobilize over long distances and biomagnify up through the food chain. The discovery of polar springtime atmospheric mercury depletion events (AMDEs) in the 1990s provides a new mechanism for enhanced atmospheric Hg deposition to the surface environment in the Arctic, yet questions remain on the process leading to AMDEs and the net contribution of AMDEs to Hg loadings to the Arctic marine ecosystem. Here we report the first systematic study of AMDEs over the open ocean conducted in the Amundsen Gulf flaw lead system from February to July 2008. A total of 31 AMDEs were observed which showed clear dependence on local sea ice environment and meteorological conditions. Enhanced concentrations of dissolved gaseous mercury were also measured in both under ice and open water conditions. Our results confirm that the sea ice environment plays a large role in Hg dynamics in the Arctic Ocean.

No description available.

Transverse Flux Machines (TFM) present some interesting problems to the machine designer, electro-magnetically and mechanically. They offer the lure of an extremely high specific output, but only, apparently, at the price of intricate three dimensional flux paths, a complicated construction and a low power factor. The research covered by this thesis was concerned with the study, development and improvement of these machines with a view to reducing the detracting aspects of the marque whilst accentuating its advantages. Extensive three dimensional finite element analysis into a wide range of TFM topologies, was coupled with practical investigations into three prototype TFMs constructed at Newcastle University. The result of this work was an improved TFM topology with comparatively good power factor, a simple single sided geometry and a very high specific output.

Conditional sampling techniques were used to analyze airbourne carbon dioxide and water vapour flux traces recorded during the FIFE experiment. Two analysis methods based on quadrant analysis were used to isolate and examine extreme contributions to estimates of the mean flux. The first method was a graphical analysis based on 'hyperbolic holes'. This method was used to attain the result that 80% of the flux-fraction is carried by 20% of the time-fraction. The second method, based on quadrant analysis, permitted the distinction of physical structures which are thought to represent the signatures of turbulent flux structures such as eddies or thermals. Overall results indicate that mean flux estimates over the FIFE site are dominated by a very few intermittent extreme events.

Graduation date: 2000

This study concludes two parts. In the first part, we establish the model of the interaction between two cell populations following the concept of the random-walk, and assume the cell movement is constrained by space limitation primarily. In the other part, the interaction model is deduced from the concept of the flux motion, and the movement is constrained by space limitation, too. Furthermore, we analyze two models to obtain the behavior of two cell populations as time is close to the initial state and far into the future. / This study concludes two parts. In the first part, we establish the model of the interaction between two cell populations following the concept of the random-walk, and assume the cell movement is constrained by space limitation primarily. In the other part, the interaction model is deduced from the concept of the flux motion, and the movement is constrained by space limitation, too. Furthermore, we analyze two models to obtain the behavior of two cell populations as time is close to the initial state and far into the future.

Thesis (Ph.D.)--University of Wollongong, 2004. / Typescript. Includes bibliographical references: leaf 152-160.

Thesis (M.S.)--University of Missouri-Columbia, 2007. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on April 9, 2009) Includes bibliographical references.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1991. / Vita. Abstract. Includes bibliographical references (107-110). Also available via the Internet.

Thesis (Ph. D.)--Ohio State University, 2007.