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39 results on '"Melman, Paul"'

6. Echocardiographic quantification of myocardial function using tissue deformation imaging, a guide to image acquisition and analysis using tissue Doppler and speckle tracking

Author

Sieswerda Gertjan T, Melman Paul G, De Boeck Bart WL, Teske Arco J, Doevendans Pieter A, and Cramer Maarten JM

Subjects
Diseases of the circulatory (Cardiovascular) system, RC666-701
Abstract

Abstract Recent developments in the field of echocardiography have allowed the cardiologist to objectively quantify regional and global myocardial function. Regional deformation (strain) and deformation rate (strain-rate) can be calculated non-invasively in both the left and right ventricle, providing information on regional (dys-)function in a variety of clinical settings. Although this promising novel technique is increasingly applied in clinical and preclinical research, knowledge about the principles, limitations and technical issues of this technique is mandatory for reliable results and for implementation both in the clinical as well as the scientific field. In this article, we aim to explain the fundamental concepts and potential clinical applicability of strain and strain-rate for both tissue Doppler imaging (TDI) derived and speckle tracking (2D-strain) derived deformation imaging. In addition, a step-by-step approach to image acquisition and post processing is proposed. Finally, clinical examples of deformation imaging in hypertrophic cardiomyopathy (HCM), cardiac resynchronization therapy (CRT) and arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) are presented.

Published
2007
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7. Blood viscosity during thrombolytic therapy with anistreplase in acute myocardial infarction

Author

Hoffman, Johannes J.M.L., Bonnier, Johannes J.R.M., Melman, Paul G., and Bartholomeus, Ingrid

Subjects
Heart attack -- Drug therapy, Anistreplase -- Physiological aspects, Blood viscosity, Thrombolytic drugs -- Evaluation, Health
Abstract

It has been postulated that a reduction in blood viscosity due to degradation of plasma fibrinogen may be of benefit to patients with acute myocardial infarction (AMI), who are treated with thrombolytic agents. The aims of this study were to investigate the time course of rheologic parameters, to identify the principal factors determining blood viscosity, and to find possible correlations between viscosity and cardiac function during thrombolytic therapy with anistreplase. Therefore, the viscosity of whole blood and plasma and the hematocrit were measured before and at 10 time points after thrombolysis in 10 patients with AMI. In addition, plasma fibrinogen and fibrin(ogen) degradation products were determined. Immediately after the start of thrombolysis, the viscosity of blood (both at high and low shear rate) and plasma decreased significantly and continued to do so for 24 hours. The mean hematocrit also decreased markedly, and even after correction for these hematocrit changes, the reduction in blood viscosity remained significant: it dacreased to 72% of pretreatment (measured at low shear rate), whereas the high-shear viscosity decreased to 95% of baseline. The viscasity of plasma significantly decreased from 1.39 [+ or -] 0.13 mPa * s (mean [+ or -] SD) before thrombolysis to 1.22 [+ or -] 0.08 mPa * s after 2 hours. There was a rapid, nearly complete depletion in fibrinogen, followed by a striking rebound after the second day. The decrease in blood viscosity lasted for 2 days after anistreplase and was mainly accounted for by the reduction in hematocrit. The contribution of fibrinogen to blood viscosity appeared less prominent. Despite these rheologic changes, no improvement in cardiac output was noticed in the patients. (Am J Cardiol 1993;71:14-18)

Published
1993

14. Binding energy of the screened exciton in two-dimensional systems.

Author

Lee, Johnson, Spector, Harold N., and Melman, Paul

Subjects
BINDING energy, EXCITON theory
Abstract

Presents a study that performed a variational calculation of the binding energy of the exciton confined in a two-dimensional structure. Function of molecular beam epitaxy; Reason that the study of the exciton effects has evoked interest; Effect of the confinement of electrons in a two-dimension structure on the screening of hydrogenic impurities in semiconducting inversion layers.

Published
1985
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15. New breakthrough design for VOAs based on electro-optic materials

Author

COHEN, STEPHEN and MELMAN, PAUL

Subjects
Multiplexers -- Design and construction, Fiber optic networks -- Equipment and supplies, Technology overview, Technology development, Fiber transmission equipment, Multiplexer, Business, Telecommunications industry
Abstract

This solid-state technology can quickly attenuate signals in optical networks and holds promise for other active comnonents. Demand for active photonic components that allow carriers to fully control the network [...]

Published
2000

18. Methods and Components for Optical Contention Resolution in High Speed Networks.

Author

GTE LABS INC WALTHAM MA, Melman, Paul, Kim, Han, GTE LABS INC WALTHAM MA, Melman, Paul, and Kim, Han

Abstract

A considerable effort has been put into the characterization of the Contention Resolution Optics (CRO) preprototype during the eight quarter of the CORD project. Of primary concern is the instability of the optical signal polarization as it progresses through the CRO. A series of tests were conducted to pin down the source of the polarization instability. A demo unit from Hewlett Packard was received and has provided a much better insight into all of the polarization instability phenomena. Additional polarization controllers were installed. A conclusion was reached that the best way to re-assemble the CR0 in such a way that its operation be high-performance and stable for several hours was that of pervasively using short spans of polarizing fiber to connect the several different elements of the CRO. (AN)

Published
1995

19. Methods and Components for Optical Contention Resolution in High-Speed Materials.

Author

GTE LABS INC WALTHAM MA, Melman, Paul, Kim, Han, GTE LABS INC WALTHAM MA, Melman, Paul, and Kim, Han

Abstract

A considerable effort has been put into the characterization of the Contention Resolution Optics (CR0) preprototype during this quarter. Of primary concern is the instability of the optical signal polarization as it progresses through the CR0. A series of tests were conducted to pin down the source of the polarization instability. A demo unit was received and has provided a much better insight into all of the polarization instability phenomena. Additional polarization controllers were installed. A conclusion was reached that the best way to reassemble the CR0 in such a way that its operation be high performance and stable for several hours was that of pervasively using short spans of polarizing fiber to connect the several different elements of the CR0.

Published
1995

28. Interferometric measurement of time-varying longitudinal cavity modes in GaAs diode lasers

Author

Melman, Paul and Carlsen, W. John

Abstract

Measurement of mode chirping in a current-modulated semiconductor laser was performed using a Michelson interferometer. For a current step excitation, the rate of this chirping decays as a function of time, and two characteristic time constants were identified. Their interpretation is discussed, and the thermal impedance of the device is calculated. In addition, the significance of such a measurement for the analysis of chirp-induced modal noise in optical fibers is discussed, and experimental results are presented.

Published
1981

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