Simulation and analysis of a digital scanning system

The analysis and simulation of the motion of a digitally-controlled digital imaging system is presented. The dynamic system consists of a scanning carriage, power transmission elements, a prime mover, and a control subsystem. The prime mover is a permanent magnet DC motor that is positioned by a direct digital control system. The scan carriage motion is mathematically modeled and simulated using ACSL and DADS simulation software. T he simulation results are compared to empirical data. It is shown that the dynamic response of the actual scan system can be predicted quite well using such simulations. Furthermore, these simulations can aid in the design of vibration-sensitive image formation devices

The Interaction of Streptococcal Enolase with Canine Plasminogen: The Role of Surfaces in Complex Formation

The enolase from Streptococcus pyogenes (Str enolase F137L/E363G) is a homo-octamer shaped like a donut. Plasminogen (Pgn) is a monomeric protein composed of seven discrete separated domains organized into a lock washer. The enolase is known to bind Pgn. In past work we searched for conditions in which the two proteins would bind to one another. The two native proteins in solution would not bind under any of the tried conditions. We found that if the structures were perturbed binding would occur. We stated that only the non-native Str enolase or Pgn would interact such that we could detect binding. We report here the results of a series of dual polarization interferometry (DPI) experiments coupled with atomic force microscopy (AFM), isothermal titration calorimetry (ITC), dynamic light scattering (DLS), and fluorescence. We show that the critical condition for forming stable complexes of the two native proteins involves Str enolase binding to a surface. Surfaces that attract Str enolase are a sufficient condition for binding Pgn. Under certain conditions, Pgn adsorbed to a surface will bind Str enolase