Wave stochastic parametric resonance (wave intensity fluctuations in a one-dimensional randomly inhomogeneous medium)

1979 ◽  
Vol 22 (2) ◽  
pp. 123-131
Author(s):  
V. I. Klyatskin
Keyword(s):  
Inhomogeneous Medium ◽  
Parametric Resonance ◽  
Wave Intensity ◽  
One Dimensional ◽  
Resonance Wave ◽  
Intensity Fluctuations

Abstract 16131: Novel Magnetic Resonance Wave Intensity Analysis in Pulmonary Hypertension

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Michael A Quail ◽  
Daniel S Knight ◽  
Jennifer A Steeden ◽  
Liesbeth Taelman ◽  
Shahin Moledina ◽  
...  
Keyword(s):  
Pulmonary Hypertension ◽  
Pulmonary Arteries ◽  
Wave Intensity ◽  
Healthy Controls ◽  
Intensity Analysis ◽  
Wave Intensity Analysis ◽  
Resonance Wave ◽  
Golden Angle ◽  
Significant Difference ◽  
Pressure And Velocity Measurements

Background: Pathological pulmonary wave reflections (WR) are a potential hemodynamic biomarker for pulmonary hypertension (PH). WR can be quantified using wave intensity analysis (WIA), typically utilizing simultaneous invasive pressure and velocity measurements. In this study we reformulated WIA to use CMR area and flow to measure reflections non-invasively. We hypothesized that this method could detect differences in WR in PH patients compared to healthy controls and could also differentiate certain PH subtypes. Methods: 20 patients with PH (35% CTEPH), mean age 54years (75% female) and 10 healthy controls, 47years (60% female) were recruited. Branch pulmonary artery (PA) flow volume (Q) and area curves (A) were used to measure wave intensity ( dI ), defined as, dI =[[Unable to Display Character: &#8710;]]Ax[[Unable to Display Character: &#8710;]]Q and dI ± =± c /4 [[[Unable to Display Character: &#8710;]]A± [[Unable to Display Character: &#8710;]]Q/ c ] 2 , where c =wave-speed. Data were acquired using a retrospectively gated, respiratory navigated, golden-angle, 10.5ms temporal resolution, phase-contrast MR sequence. All patients also underwent right heart cardiac catheterization for pressure and vascular resistance (PVR) measurement, median interval 6 days (IQR 2-11days). The presence of proximal clot in CTEPH patients was determined from contemporaneous CT/angiographic data. Results: A backwards-travelling compression wave (BCW) was present in both left and right PAs of all PH patients, but was absent in all controls ( p =6e -8 ). A backwards-travelling expansion/suction wave was present in the 19/20 branch PAs of controls, and only 4/40 PAs in patients ( p < 0.0001). The area under the BCW was associated with a sensitivity of 100% (95% CI 63-100%) and specificity of 91% (95% CI 75-98%) for the presence of clot in the proximal pulmonary arteries of patients with CTEPH. Conclusions: Noninvasive pulmonary WIA accurately delineates pulmonary vascular health and disease. The main findings of this study were: i) There was a significant difference in WIA metrics between patients and controls, in particular, the presence of a BCW was specifically associated with the presence of PH; and ii) The magnitude of the BCW area showed discriminatory capacity for the presence of proximal PA clot in patients with CTEPH. We believe that these results demonstrate that WIA could be used in the non-invasive assessment of PH.

scholarly journals Spatial wave intensity correlations in quasi-one-dimensional wires

2006 ◽  
Vol 74 (4) ◽  
Author(s):  
Gabriel Cwilich ◽  
Luis S. Froufe-Pérez ◽  
Juan José Sáenz
Keyword(s):  
Wave Intensity ◽  
One Dimensional

Article

1998 ◽  
Vol 76 (11) ◽  
pp. 1633-1641
Author(s):  
Luc Tremblay ◽  
Serge Lacelle ◽  
Charles G Fry
Keyword(s):  
Porous Media ◽  
Pyrex Glass ◽  
Nmr Imaging ◽  
Porous Network ◽  
Intensity Correlation ◽  
Geometric Means ◽  
Statistical Characterization ◽  
One Dimensional ◽  
Intensity Fluctuations ◽  
The One

A study of the intensity fluctuations in one-dimensional NMR microimaging profiles of imbibed porous Pyrex glass filters is presented. An approach to characterize some aspects of the macroscopic randomness from the NMR microimaging profiles of this porous medium is developed. Statistical properties, such as the arithmetic and geometric means, of the distributions of peak separations between the intensity fluctuations are shown to reveal information about the pore size and the pore-to-pore distances in porous media. The intensity-intensity correlation functions of the one-dimensional NMR profiles display an interplay, as a function of length scale, among the dimensions of the porous network and its embedding space, and their respective dimensions in the projections. Corroboration of these NMR results are achieved with similar analysis of SEM two-dimensional images and their corresponding one-dimensional projections obtained with the same porous Pyrex glass. The approach developed to characterize the macroscopic randomness in these porous glass filters should prove generic for the study of other random materials.Key words: NMR imaging, scanning electron microscopy, porous media, disorder, statistical characterization.

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