Abstract: An automobile rigid convertible roof (4) retracts horizontally rearward over the rear part of the upper body. The rear end of the roof is supported by two external elongated struts (12L and 12R) which are permanently attached to the rear corners of the roof at their upper ends and retract with it as a unit. Strut bottom rollers (18) are guided by guides (22) mounted adjacent the vehicle rear deck. The struts (12) are outside of the vehicle cockpit enclosure. The retracted roof is moved horizontally so that the retracted roof panel does not interfere with rear vision from the cockpit and in the retracted position does not use any cockpit or vehicle trunk volume for roof storage.

Abstract: A plurality of different liquid solutions are connected to an input of a pump system having at least two displacement chambers and in a manner to control the proportions of each constituent that are taken into each chamber during its intake stroke. The outputs of the chambers are connected to a common liquid output. The chambers are driven by independently controllable motors so that the discharge stroke may be chosen to have some parameters, such as speed profile and duration, that are different than during the intake stroke. As a result, both chambers may simultaneously discharge liquid through the common output, if desired. The proportion of constituents may be made different each time one of the chambers is filled, so the simultaneous discharge of the chambers allows a gradual, carefully controlled change from the mixture of one chamber to that of the other.

Abstract: Variations in the intensity of a light source and the sensitivity of a fluorescence detector photo-multiplier tube are simultaneously compensated by measuring the intensity (I.sub.LS1) of the light source at the sample excitation frequency with a silicon detector, measuring the intensity (I.sub.LS2) of the light source at the emission frequency with another silicon detector, measuring with the photo-multiplier detector the intensity (I.sub.S) of the sample's fluorescence and the intensity (I.sub.

Abstract: An instrument is disclosed which performs measurements and calculates the average and the variance of the measurements. The particular instrument illustrating the invention is a spectrophotometer which measures sets of dark, reference and sample spectra for use in calculating an average absorbance spectrum and its variance. The measurements are performed in an order which enables the cancellation of measurement variation due to variation in instrument response. The order of measurements is determined by measurement subroutines which can be aggregated to produce a series of measurements performed over a user selected period of integration time.

Abstract: An instrument is disclosed which performs measurements and calculates the average and the variance of the measurements. The particular instrument illustrating the invention is a spectrophotometer which measures sets of dark, reference and sample spectra for use in calculating an average absorbance spectrum and its variance. The measurements are performed in an order which enables the cancellation of measurement variation due to variation in instrument response. The order of measurements is determined by measurement subroutines which can be aggregated to produce a series of measurements performed over a user selected period of integration time.