Optical Diagnostics on Helical Flux Compression Generators

Explosively driven magnetic flux compression (MFC) has been object of research for more than three decades. Actual interest in the basic physical picture of flux compression has been heightened by a newly started Department of Defense (DoD) Multi-University Research Initiative. The emphasis is on helical flux compression generators comprising a hollow cylindrical metal liner filled with high explosives and at least one helical coil surrounding the liner. After the application of a seed current, magnetic flux is trapped and high current is generated by moving, i.e., expanding, the liner explosively along the winding of the helical coil. Several key factors involved in the temporal development can be addresses by optical diagnostics. 1) The uniformity of liner expansion is captured by framing camera photography and supplemented by laser illuminated high spatial and temporal resolution imaging. Also, X-ray flash photography is insensitive to possible image blur by shockwaves coming from the exploding liner. 2) The thermodynamic state of the shocked gas is assessed by spatially and temporally resolved emission spectroscopy. 3) The moving liner-coil contact point is a possible source of high electric losses and is preferentially monitored also by emission spectroscopy. Since optical access to the region between liner and coil is not always guaranteed, optical fibers can he used to extract light from the generator. The information so gained will give, together with detailed electrical diagnostics, more insight in the physical loss mechanisms involved in MFC

Accuracy and repeatability of wrist joint angles in boxing using an electromagnetic tracking system

© 2019, The Author(s). The hand-wrist region is reported as the most common injury site in boxing. Boxers are at risk due to the amount of wrist motions when impacting training equipment or their opponents, yet we know relatively little about these motions. This paper describes a new method for quantifying wrist motion in boxing using an electromagnetic tracking system. Surrogate testing procedure utilising a polyamide hand and forearm shape, and in vivo testing procedure utilising 29 elite boxers, were used to assess the accuracy and repeatability of the system. 2D kinematic analysis was used to calculate wrist angles using photogrammetry, whilst the data from the electromagnetic tracking system was processed with visual 3D software. The electromagnetic tracking system agreed with the video-based system (paired t tests) in both the surrogate ( 0.9). In the punch testing, for both repeated jab and hook shots, the electromagnetic tracking system showed good reliability (ICCs > 0.8) and substantial reliability (ICCs > 0.6) for flexion–extension and radial-ulnar deviation angles, respectively. The results indicate that wrist kinematics during punching activities can be measured using an electromagnetic tracking system

Effect of carbon starvation on toluene degradation activity by toluene monooxygenase-expressing bacteria

Subsurface bacteria commonly exist in a starvation state with only periodic exposure to utilizable sources of carbon and energy. In this study, the effect of carbon starvation on aerobic toluene degradation was quantitatively evaluated with a selection of bacteria representing all the known toluene oxygenase enzyme pathways. For all the investigated strains, the rate of toluene biodegradation decreased exponentially with starvation time. First-order deactivation rate constants for TMO-expressing bacteria were approximately an order of magnitude greater than those for other oxygenase-expressing bacteria. When growth conditions (the type of growth substrate and the type and concentration of toluene oxygenase inducer) were varied in the cultures prior to the deactivation experiments, the rate of deactivation was not significantly affected, suggesting that the rate of deactivation is independent of previous substrate/inducer conditions. Because TMO-expressing bacteria are known to efficiently detoxify TCE in subsurface environments, these findings have significant implications for in situ TCE bioremediation, specifically for environments experiencing variable growth-substrate exposure conditions.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45353/1/10532_2005_Article_9014.pd

Studies on the mechanism of induction of prophage lambda.

Treatment of bacteriophage lambda lysogens of Escherichia coli with various physical and chemical agents leads to induction. This thesis reports some investigations into the mechanism of induction, in particular following UV irradiation. Lysogens of different ages were found to vary in the efficiency with which they are induced by small doses of UV irradiation, being least inducible at division and most inducible at a time which coincides approximately with the time when rounds of DNA replication are thought to be terminated. One can indirectly induce a ? prophage by introducing into a lysogen an entire irradiated plasmid. Experiments are described showing that a ?N- mutant is unable to indirectly induce a prophage when irradiated. This suggests that the fortuitous acquisition by mutation of the ability to be maintained semi-stably in the cell in a non-integrated state is not sufficient to give a replicon the ability, when irradiated, to indirectly induce. Evidence is also presented in support of the correlation which exists between treatments leading to induction and those leading to the inhibition of cell division. These results have been considered in terms of three general hypotheses. (1) Induction is caused by the accumulation of some component involved in the initiation of rounds of DNA replication. This is clearly inconsistent with data showing the age at which lysogens are most readily inducible. (2) Induction is related to the activity of some DNA repair system. This hypothesis is consistent with much of the data presented in this thesis but is difficult to reconcile in its simplest form with the observation that only certain types of irradiated DNA indirectly induce. (3) Induction is related to the inhibition of cell division. This hypothesis is consistent with published work and receives support from data presented in this thesis