John Burkhardt

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PURPOSE To measure the pressure exerted by maxillary edentulous impressions composed of 3 commonly used impression materials using four different impression tray configurations. MATERIALS AND METHODS The study was performed using an oral analog that simulated an edentulous maxillary arch. Three pressure transducers were imbedded in the oral analog, 1 in(More)
A major international experiment on ammonia (NH 3) biosphere-atmosphere exchange was conducted over intensively managed grassland at Braunschweig, Germany. The experimental strategy was developed to allow an integrated analysis of different features of NH 3 exchange including: a) quantification of nearby emissions and advection 5 effects, b) estimation of(More)
M. A. Sutton, E. Nemitz, C. Milford, C. Campbell, J. W. Erisman, A. Hensen, P. Cellier, M. David, B. Loubet, E. Personne, J. K. Schjoerring, M. Mattsson, J. R. Dorsey, M. W. Gallagher, L. Horvath, T. Weidinger, R. Meszaros, U. Dämmgen, A. Neftel, B. Herrmann, B. E. Lehman***†, C. Flechard, and J. Burkhardt Centre for Ecology and Hydrology (Edinburgh(More)
Microrobotics is a rapidly growing field with promising applications in microsurgery and microassembly. A challenge in these systems is providing power and control signals to the robot. This project explores crawling robots that are powered and controlled through a global mechanical vibration field. Structures within the robot will cause it to respond to(More)
There is an active debate in toxicology literature about the utility of animal testing vis-a-vis alternative in vitro paradigms. To provide a balanced perspective and add to this discourse it is important to review the current paradigms, explore pros and cons of alternatives, and provide a vision for the future. The fundamental goal of toxicity testing is(More)
Climatological studies of blocking in the Southern Hemisphere (SH) demonstrate that blocking events are less common (e.g. Lejenas, 1984; Renwick 1998), and are weaker (e.g. Wiedenmann, et al., 2002; hereafter WLMT02) throughout the SH when compared to their NH counterparts. WLMT02 implied that the relative roles in the interaction between planetary-scale(More)
Modeling the dynamic chemical interactions of atmospheric ammonia and other trace gases with measured leaf surface wetness in a managed grassland canopy J. Burkhardt, C. R. Flechard, F. Gresens, M. E. Mattsson, P. A. C. Jongejan, J. W. Erisman, T. Weidinger, R. Meszaros, E. Nemitz, and M. A. Sutton Institute for Crop Science and Resource Conservation,(More)
The field of microrobotics has vast applications including non-invasive surgery, targeted drug delivery, and telemetry. Many groups are developing or have developed magnetically based actuation methods for microrobotics. These magnetically based systems can potentially lead to undesirable effects on the human body. Acoustic control provides an interesting(More)
In recent years, several studies have partitioned atmospheric quantities into planetary and synoptic scale components in order to examine either the relative role of each scale and their interactions, or to examine the nature of the interactions themselves (e.g., Tsou and Smith, 1990; Tracton, 1990; Lupo and Smith, 1995b; Lupo, 1997; Marques and Rao, 1999;(More)