Abstract: In one aspect, the invention relates to an immunogenic composition that includes a mutant Clostridium difficile toxin A and/or a mutant Clostridium difficile toxin B. The mutant toxin may include a glucosyltransferase domain having at least one mutation and a cysteine protease domain having at least one mutation, relative to the corresponding wild-type C. difficile toxin. The mutant toxins may include at least one amino acid that is chemically crosslinked. In another aspect, the invention relates to methods and compositions for use in culturing Clostridium difficile and in producing C. difficile toxins.

Abstract: Micro-electromechanical apparatus and method with position sensor compensation to compensate for sensor drift. A preferred embodiment comprises modifying the intensity of a light source used in position detection to maintain a constant sum of the voltages output from photodetectors receiving light from the light source. Preferred embodiments may be implemented in digital signal processor code, or external to the processor in analog circuitry. By adjusting light source intensity, position calculations may be performed without normalization, and thus without a time-consuming division operation.

Abstract: Micro-electromechanical apparatus and method with position sensor compensation to compensate for sensor drift. A preferred embodiment comprises modifying the intensity of a light source used in position detection to maintain a constant sum of the voltages output from photodetectors receiving light from the light source. Preferred embodiments may be implemented in digital signal processor code, or external to the processor in analog circuitry. By adjusting light source intensity, position calculations may be performed without normalization, and thus without a time-consuming division operation.

Abstract: Signal conversion apparatus and method with coarse and fine digital to analog converters. The output of the coarse DAC has a high gain to support wide voltage swings, while the fine DAC has a low gain to support accurate tracking control. The two outputs are combined in an analog summing junction. The apparatus and method may comprise a low pass filter connected to the coarse DAC output. The filter may be switched off during large changes to provide rapid system response, and switched on during position holding to attenuate noise from the coarse DAC. The apparatus and method may comprise a pre-charging capacitor in the filter, wherein the capacitor may be pre-charged when the filter is off, reducing the switch transient when the filter is switched on.