Electrocatalytic tetracycline oxidation at a mixed-valent ruthenium oxide--ruthenium cyanide-modified glassy carbon electrode and determination of tetracyclines by liquid chromatography with electrochemical detection

Mixed-valent films of ruthenium oxide-ruthenium cyanide were electrodeposited onto glassy carbon and characterized for the electrocatalytic oxidation of tetracycline. The currents produced by tetracycline were higher than from previously reported electrode modifications or pretreatments. In H(2)SO(4) pH 1.0 + 0.5 M K(2)SO(4), the second-order rate constant for the reaction between tetracycline and the Ru(III/IV) couple of ruthenium oxide was 3 x 10(5) +/- 1 x 10(5) mol(-1) cm(3) s(-1), and the rate of charge diffusion through the films was 4.5 x 10(-7) +/- 3.5 x 10(-7) cm(2) s(-1). Reaction was localized at the film-solution interface. When used as detectors in liquid chromatography (in H(3)PO(4) pH 2.5 + 0.1 M KH(2)PO(4) + 20% CH(3)CN, E = 1.10 V vs SCE), the electrodes gave limits of detection (>3 S/N) of 0.1 ppm for tetracycline and oxytetracycline and 0.5 ppm for doxycycline and chlorotetracycline. These limits were suitable for FDA and Codex Alimentarius guidelines for tetracyclines in food. Recoveries of the four tetracyclines from sea and freshwater shrimp were in the range 73-111%, which was higher or similar to the previously reported recoveries from shrimp.     

Airborne video registration and traffic-flow parameter estimation

This paper investigates airborne helicopter video for estimating traffic parameters. Roll, pitch, and yaw of the helicopter make the video unstable, difficult to view, and the derived parameters less accurate. To correct this, a frame-by-frame video-registration technique using a feature tracker to automatically determine control-point correspondences is proposed. This converts the spatio-temporal video into temporal information, thereby correcting for airborne platform motion and attitude errors. The registration is robust, with the residual jitter being less than a few pixels over hundreds of frames. A simple vehicle-detection scheme identifies vehicle locations in the video, which are then tracked by the feature tracker, enabling us to estimate average velocity, instantaneous velocity, and other parameters automatically to within 10% of manual measurements. The entire process of registration, detection, tracking, and estimation takes only a few seconds for each frame. A prototype multimedia geographic information system (GIS) is created as a visualization tool for viewing the registered video, other airborne or satellite imagery, and data pertaining to georeferenced locations within a base map.     

Combustion Synthesis of Glass (B2O3-Al2O3-MgO)-Ceramic (TiB2) Composites

The combustion synthesis, or self-propagating high temperature synthesis (SHS), technique has been used to produce glass ceramic composites that have a glass matrix based on B₂O₃-MgO-Al₂O₃and a crystalline ceramic phase of TiB₂. Conditions for producing glassy materials by the SHS technique are discussed and the thermodynamics of these combustion reactions are analyzed. The combustion characteristics, i.e., ignition energy, combustion temperature, and wave velocity have been determined. Green density of the pellets had a significant effect on the combustion characteristics. Green pellets with low density were used to reduce heat loss, thus enabling the synthesis of those compositions having low adiabatic temperatures. The glass-forming region of these SHS glasses was found to be in relatively good agreement with that of samples produced by the traditional furnace-melting method.     

Automated feature detection in digital images of skin

This paper presents a new approach to the detection of cutaneous features such as pigmented moles, pores and hair in digital images. We show that by considering the digitized image to be a 3-D terrain with brightness being height, common skin features appear as 'pits' in the terrain. Pits contain a great deal of information about local features in a form that can be easily extracted and analyzed. Pigmented lesions of clinical interest typically have pit characteristics which can be used to separate them from other features. We show empirically that, by creating a statistical database, on the average over 99% of pits can be classified correctly after only a few training images are established for a subject. When attempting to detect pigmented lesions, mean sensitivity ranges from 78% to 98%, depending on imaging conditions and the classification algorithm used. Using image compression, the speed of this screening technique is shown to be increased by a factor of 4 without loss of sensitivity.     

Avoidance of additional aliasing in multipass image rotations

The two-pass (or multipass) image geometric transformation algorithm is ideally suited to real-time, parallel implementation, but is known to introduce frequency aliasing during rotation, over and above any aliasing which may result from the usual one-pass algorithm. We develop a unified framework and theory that precisely explains this added-aliasing for many of the well-known multipass algorithms, and show that it is usually less than might be expected at first sight. In some cases, the aliasing occurs in nondestructive, and therefore, theoretically recoverable, forms. We also show that the aliasing is very easily reduced, or avoided altogether, while commenting that this problem should be considered as a special case of a general alias-avoidance strategy in geometric transformation. Finally, we include some examples of multipass image rotations which seem to confirm our predictions.     

Medical interface research at the HIT Lab

The Human Interface Technology Laboratory (HIT Lab) is a multi-disciplinary research and development lab whose work centers on novel approaches to human interface technology. Lab researchers represent a wide range of disciplines from across the University of Washington campus, including engineering, medicine, education, social sciences, architecture, and the design arts. We describe here a representative sampling of past and current HIT Lab research and development activities related to medicine, including virtual reality and augmented/mixed reality applications for direct patient therapy, tools for basic medical education and procedure training, novel approaches to medical image acquisition and display, and new visualization methods in medical informatics.