Biomedical subjects

A Egner

Publications and source records attributed to A Egner.

4 recordsLinked to original sources

PubMed2002

Comparison of the axial resolution of practical Nipkow-disk confocal fluorescence microscopy with that of multifocal multiphoton microscopy: theory and experiment.

We compare the axial sectioning capability of multifocal confocal and multifocal multiphoton microscopy in theory and in experiment, with particular emphasis on the background arising from the cross-talk between adjacent imaging channels. We demonstrate that a time-multiplexed non-linear excitation microscope exhibits significantly less background and therefore a superior axial resolution as compared to a multifocal single-photon confocal system. The background becomes irrelevant for thin (< 15 microm) and sparse fluorescent samples, in which case the confocal parallelized system exhibits similar or slightly better sectioning behaviour due to its shorter excitation wavelength. Theoretical and experimental axial responses of practically implemented microscopes are given.

Fluorescence Polarization↗

PubMed2001

Telehealth: reaching out to newly injured spinal cord patients.

OBJECTIVES: The authors present preliminary results on health-related outcomes of a randomized trial of telehealth interventions designed to reduce the incidence of secondary conditions among people with mobility impairment resulting from spinal cord injury (SCI). METHODS: Patients with spinal cord injuries were recruited during their initial stay at a rehabilitation facility in Atlanta. They received a video-based intervention for nine weeks, a telephone-based intervention for nine weeks, or standard follow-up care. Participants are followed for at least one year, to monitor days of hospitalization, depressive symptoms, and health-related quality of life. RESULTS: Health-related quality of life was measured using the Quality of Well-Being (QWB) scale. QWB scores (n = 111) did not differ significantly between the three intervention groups at the end of the intervention period. At year one post discharge, however, scores for those completing one year of enrollment (n = 47) were significantly higher for the intervention groups compared to standard care. Mean annual hospital days were 3.00 for the video group, 5.22 for the telephone group, and 7.95 for the standard care group. CONCLUSIONS: Preliminary evidence suggests that in-home telephone or video-based interventions do improve health-related outcomes for newly injured SCI patients. Telehealth interventions may be cost-saving if program costs are more than offset by a reduction in rehospitalization costs, but differential advantages of video-based interventions versus telephone alone warrant further examination.

Adolescent↗

PubMed2000

Fluorescence microscopy with diffraction resolution barrier broken by stimulated emission.

The diffraction barrier responsible for a finite focal spot size and limited resolution in far-field fluorescence microscopy has been fundamentally broken. This is accomplished by quenching excited organic molecules at the rim of the focal spot through stimulated emission. Along the optic axis, the spot size was reduced by up to 6 times beyond the diffraction barrier. The simultaneous 2-fold improvement in the radial direction rendered a nearly spherical fluorescence spot with a diameter of 90-110 nm. The spot volume of down to 0.67 attoliters is 18 times smaller than that of confocal microscopy, thus making our results also relevant to three-dimensional photochemistry and single molecule spectroscopy. Images of live cells reveal greater details.

Escherichia coli↗

PubMed2000

Time multiplexing and parallelization in multifocal multiphoton microscopy

We investigate the imaging properties of high-aperture multifocal multiphoton microscopy on the basis of diffraction theory. Particular emphasis is placed on the relationship between the sectioning property and the distance between individual foci. Our results establish a relationship between the degree of parallelization and the axial resolution for both two- and three-photon excitation. In addition, we show quantitatively that if a matrix of temporal delays is inserted between the individual foci, it is, for the first time to our knowledge, possible to solve the classical conflict between the light budget and the sectioning property in three-dimensional microscopy and to provide a virtually unlimited density of foci at best axial resolution.

Journal Article↗