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D C Peters

Publications and source records attributed to D C Peters.

24 records · Page 2Linked to original sources
PubMed1982

Multi-parameter, computer controlled operation of a FACS II cell sorter.

The ease of operation and versatility of a FACS II cell sorter were improved by replacing the original pulse height analyzer (PHA) with a computer-based dual parameter PHA and a single channel analyzer (SCA). An ND620 LSI-11 based PHA is now used to generate the sorting decisions. Sorting windows are created by intensifying one or more regions of any shape on the PHA single or dual parameter histograms. For three parameter operation, the third parameter SCA contols the dual parameter information sent to the analyzer. The SCA can also trigger an abort circuit during the PHA 15 microsecond analyzing dead time, improving the purity of the sorted fraction. The electronics that interfaces the new PHA to the sorter replaces all of the original FACS II analog signal processing circuitry with an interchangeable circuit board. The principles involved should apply to any cell sorter.

Cell Separation↗
PubMed1979

A comparison of mercury arc lamp and laser illumination for flow cytometers.

Optical differences between a mercury arc lamp and a laser-illuminated flow cytometer are compared. The distributions of spectral intensities of the two light sources are shown in relation to the excitation characteristics of the fluorescent dyes acriflavine, chromomycin A3, mithramycin, ethidium bromide, Hoechst 33258, and 4,6-diamidino-2-phenylindole (DAPI). Fluorescence intensities of microspheres and Hoechst 33258-stained mouse sperm are compared in the two cytometers. The optical efficiencies are similar and depend on the match of the excitation characteristics of the stain with the emission spectra of the light source.

Animals↗
PubMedDate not supplied

Effects of through-plane myocardial motion on phase-difference and complex-difference measurements of absolute coronary artery flow.

We have previously reported on a complex-difference (CD) flow measurement technique that produces more accurate results than the phase-difference (PD) flow measurement technique due to the greater immunity of the former method to partial volume effects. We report here on some of the ways in which through-plane myocardial motion affects the accuracy of absolute coronary artery flow measurements obtained using the PD and CD techniques. We also discuss motion correction schemes that can be applied to the PD and CD processing methods to improve their accuracy. Computer simulations have been performed to assess the magnitude of the errors associated with these flow measurement techniques when they are applied to small vessels that are attached to a moving background. Laminar and plug flow, with and without complete background suppression, have been considered. Experiments with a moving vessel phantom have been conducted to test the performance of the PD and CD flow measurement techniques in circumstances similar to those simulated. The simulations and the experiments showed that, after corrections for through-plane motion are made, the CD method generally yields more accurate flow results than the PD method. As shown by the simulations, however, both methods yield compromised results due to subtle saturation effects that occur when the direction of myocardial motion is opposite the direction of blood flow. Unvalidated PD and CD measurements of coronary artery flow waveforms in human volunteers are presented to illustrate the magnitude of the proposed through-plane motion effects in vivo.

Blood Flow Velocity↗