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1,291 results on '"Hess, O"'

215. Ultrashort Dynamics in Quantum Dot Waveguides: Theoretical Analysis and Experimental Investigations

Author

Gehrig, E., Poel, Mike van der, Birkedal, Dan, Hvam, Jørn Märcher, Hess, O., Gehrig, E., Poel, Mike van der, Birkedal, Dan, Hvam, Jørn Märcher, and Hess, O.

Abstract

Experimental pump-probe measurements and computational modeling on the basis of spatially resolved Quantum Dot Maxwell-Bloch equations allow identification of the processes underlying the ultrafast dot dynamics.

Published
2004

223. Arterielle Gefäßsteifigkeit und Pulswellenanalyse

Author

Baulmann, J, primary, Nürnberger, J, additional, Slany, J, additional, Schmieder, R, additional, Schmidt-Trucksäss, A, additional, Baumgart, D, additional, Cremerius, P, additional, Hess, O, additional, Mortensen, K, additional, and Weber, T, additional

Published
2010
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239. Fluorescence spectroscopy for identification of atherosclerotic tissue

Author

Bosshart, F., Utzinger, U., Hess, O M., Wyser, J., Mueller, A., Schneider, J., Niederer, P., Anliker, M., Krayenbuehl, H P., University of Zurich, and Bosshart, F

Subjects
2737 Physiology (medical), 570 Life sciences, biology, 610 Medicine & health, 1314 Physiology, 142-005 142-005, 2705 Cardiology and Cardiovascular Medicine
Abstract

Objective: Vessel perforation and limited steerability of the laser light are the major limitations of laser angioplasty. To improve steerability fluoresence spectroscopy has been proposed for identification of atherosclerotic plaques. The aim was to investigate this. Methods: Fluorescence spectroscopy with three different excitation wavelengths (325 nm, 380 nm, 450 nm) was tested in an emission range of 400 nm to 600 nm. Intensity ratios at 480/420 nm were determined in different types of blood vessels. Necropsy material from 40 patients (punch biopsies of 4 mm diameter from the coronary and carotid artery as well as from the ascending and descending aorta) was studied spectroscopically. Histological alterations of the vessel wall were assessed by a semiquantitative score (0 to 10 points): (a) normal tissue, 0 to 2 points (mean=0.25; n=38); (b) mild atherosclerotic lesions, 3 to 5 points (mean=3.35; n=39); (c) severe atherosclerotic lesions, ≥ 6 points (mean=6.75; n=43). Results: Best spectroscopic results were obtained with an excitation wavelength of 325 nm. In samples with severe atherosclerotic lesions the fluoresence spectra showed a significant reduction of the emitted wavelength intensities when compared to normal tissue. There was a clear separation of the fluorescence spectra between normal and mild as well as between normal and severe atherosclerotic lesions; normal tissue showed an increased intensity in the range from 420 nm to 540 nm, whereas atherosclerotic lesions had no or only a small peak at 480 nm. There was a significant correlation between the semiquantitative score (n=120) and the fluorescence ratio at 480/420 nm (excitation wavelength 325 nm) with a correlation coefficient of 0.87. The spectroscopic results showed no differences between the samples taken from different types of vessels. Conclusions: Fluorescence spectroscopy allows a reliable identification of normal and atherosclerotic lesions. The close correlation between the emitted light intensity ratio at 480/420 nm and the histological alterations of the vessel wall suggests a relationship between vessel wall fluorescence and the atherosclerotic alterations of the wall

Published
1992

248. Quantum Monte Carlo perturbation calculations of interaction energies

Author

Caffarel M and Hess O

Subjects
Hybrid Monte Carlo, Physics, Quantum electrodynamics, Quantum Monte Carlo, Monte Carlo method, Dynamic Monte Carlo method, Monte Carlo method in statistical physics, Diffusion Monte Carlo, Kinetic Monte Carlo, Atomic and Molecular Physics, and Optics, Monte Carlo molecular modeling
Published
1991

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