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121 results on '"Jacobsen V"'

1. Investigation of the SOI microdosimeter for high LET ion measurements

Author

Vohradsky, J., primary, Pan, V., additional, Bennett, D., additional, Jacobsen, V. L., additional, Bolst, D., additional, Peracchi, S., additional, Pastuovic, Z., additional, Guatelli, S., additional, Petasecca, M., additional, Lerch, M., additional, Povoli, M., additional, Kok, A., additional, Inaniwa, T., additional, Tran, L. T., additional, and Rosenfeld, A. B., additional

Published
2023
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7. Hydrodynamic forces on pipelines: model tests

Author

Bryndum, M.B., Jacobsen, V., and Tsahalis, D.T.

Subjects
Hydrodynamics -- Research, Pipe lines -- Hydrodynamics, Science and technology
Abstract

The underwater hydrodynamic behavior of a submarine pipeline is studied through model tests. The tests are conducted in a flume wherein the hydrodynamic forces acting on a set of model pipes subjected to a constant flowrate are measured by means of shear force transducers. The tests' outcome is then analyzed by applying three different methods, including the Fourier decomposition technique. A very good agreement is noted between the results.

Published
1992

14. Involvement of calcitonin gene-related peptide in migraine:regional cerebral blood flow and blood flow velocity in migraine patients

Author

Lassen, L H, Jacobsen, V B, Haderslev, P A, Sperling, B, Iversen, Helle Klingenberg, Olesen, J, Tfelt-Hansen, P, Lassen, L H, Jacobsen, V B, Haderslev, P A, Sperling, B, Iversen, Helle Klingenberg, Olesen, J, and Tfelt-Hansen, P

Abstract

Calcitonin gene-related peptide (CGRP)-containing nerves are closely associated with cranial blood vessels. CGRP is the most potent vasodilator known in isolated cerebral blood vessels. CGRP can induce migraine attacks, and two selective CGRP receptor antagonists are effective in the treatment of migraine attacks. It is therefore important to investigate its mechanism of action in patients with migraine. We here investigate the effects of intravenous human alpha-CGRP (halphaCGRP) on intracranial hemodynamics. In a double-blind, cross-over study, the effect of intravenous infusion of halphaCGRP (2 mug/min) or placebo for 20 min was studied in 12 patients with migraine without aura outside attacks. Xenon-133 inhalation SPECT-determined regional cerebral blood flow (rCBF) and transcranial Doppler (TCD)-determined blood velocity (V (mean)) in the middle cerebral artery (MCA), as well as the heart rate and blood pressure, were the outcome parameters. No change of rCBF was observed at the end of infusion [1.2% +/- 1.7 with halphaCGRP, vs. -1.6% +/- 3.1 with placebo (mean +/- SD)] (P = 0.43). V (mean) in MCA decreased to 13.5% +/- 3.6 with halphaCGRP versus 0.6% +/- 1.8 with placebo (P < 0.005). Since rCBF was unchanged, this indicates a dilation of the MCA. halphaCGRP induced a decrease in MAP (12%) (P < 0.005) and an increase in heart rate (58%) (P < 0.0001). CGRP dilates cerebral arteries, but the effect is so small that it is unlikely to be the only mechanism of CGRP-induced migraine.

Published
2008

31. Cross-Flow Vibrations of a Pipe Close to a Rigid Boundary

Author

Jacobsen, V., Bryndum, M. B., Nielsen, R., and Fines, S.

Abstract

The paper describes the results of a model test series with the purpose of determining the hydroelastic vibrations of a nearbed pipeline span exposed to flow conditions created by steady current, waves and waves superimposed on steady current. The study has been conducted using a model composed of a spring-mounted rigid pipe segment and a flat plate simulating the sea bed. The hydroelastic cross-flow vibrations of the pipe segment are presented as function of the flow velocity, flow condition (waves and/or steady current) and the relative distance of the pipe to the seabed. A simple approach to analyze the vibrations caused by an irregular wave train is presented.

Published
1984
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50. Reduced photobleaching of chromophores close to a metal surface

Author

Fernando D. Stefani, Maximilian Kreiter, Wolfgang Knoll, Volker Jacobsen, Krasimir Vasilev, Vasilev, Krasimir Atanasov, Stefani, F, Jacobsen, V, Knoll, Wolfgang, and Kreiter, M

Subjects
Electromagnetic field, Surface (mathematics), Physics::Biological Physics, Photobleaching, Photochemistry, Chemistry, General Physics and Astronomy, Chromophore, Fluorescence, Molecular physics, Metal, Kinetics, Electromagnetic Fields, Metals, visual_art, Excited state, visual_art.visual_art_medium, Physical and Theoretical Chemistry, Excitation
Abstract

The photobleaching of chromophores in front of a metal film is measured by recording the emitted fluorescence intensity from an ensemble of chromophores as a function of time. A strong dependence of the photostability on the distance from the metal surface is found. The experimental data are well described in a classical electromagnetic model with the additional assumption that photobleaching occurs at a constant rate from the excited state. The metal interface influences the photostability of the chromophores in two ways, first by altering the excitation rate by local enhancement of the electromagnetic field and second by altering the electromagnetic decay rate.

Published
2004
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