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Wall Movements (wall + movement)
Selected AbstractsForced Alveolar Flows and Mixing in the LungPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2009David Borer The air flows deep inside the lung are not only important in gas exchange processes but they also determine the efficiency of particle deposition and retention. The study aims at quantifying the relative influence of different flow components in the transport of small particles in alveolar geometries such as convective breathing patterns, wall movement, gravitational settling and Brownian motion. In addition, the possibility and efficiency of external forcing is studied, relying on the mechanism of internal acoustic streaming. A viscous oscillating boundary layer flow is converted into a steady, viscosity-independent bulk motion which is very efficient at low Reynolds numbers. The streaming can be controlled by external parameters (excitation amplitude, frequency, beam shape) and may thus be of diagnostic and therapeutic relevance. Numerical simulations are performed to analyze the flow patterns in 3D model geometries and to measure deposition rates. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Pilot study of operative fixation of fractured ribs in patients with flail chestANZ JOURNAL OF SURGERY, Issue 11 2009Silvana Marasco Abstract Background:, Flail chest is a serious injury in trauma with a significant mortality rate, and long-term pain and disability. Traditionally, management has consisted of internal pneumatic splinting, leading to prolonged periods of mechanical ventilation, and its attendant complications. The aim of this study was to assess the safety of operative fixation of broken ribs in flail chest using absorbable prostheses. Methods:, Thirteen consecutive patients with severe flail chest injury were enrolled in this pilot study. Surgery was planned after viewing three-dimensional reconstructions of the computed tomography scans of the chest. The plates were applied to the external cortical surface of the rib after reducing the fracture. Segmentally fractured ribs were usually plated only once to convert the flail segment to simple fractured ribs and correct the paradoxical wall motion abnormality. Results:, All patients had a good surgical result. On average, four ribs were fixed per patient. All patients were able to be weaned from mechanical ventilation and all patients were discharged from the hospital. There were no deaths. No plates had to be removed. In all patients, the flail chest was successfully stabilized and paradoxical chest wall movement was eliminated. Conclusion:, This pilot study of operative fixation of broken ribs in patients with flail chest, using absorbable plates and screws, has shown the technique to be safe and effective. On the basis of these results, a prospective randomized trial has commenced at The Alfred Hospital, comparing this management strategy with conservative management. [source] The influence of the construction process on the deformation behaviour of diaphragm walls in soft clayey groundINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 7 2006R. Schäfer Abstract Conventional numerical predictions of deep excavations normally neglect the construction process of the retaining structure and choose the earth pressure at rest as initial condition at the beginning of the simulation. The presented results of simulation and measurements during the construction process of the Taipei National Enterprise Center show, that such an assumption leads to an underestimation of the horizontal wall deflection, the surface ground settlements as well as the loading of the struts in case of normally to slightly over-consolidated clayey soil deposits. The stepwise installation process of the individual diaphragm wall panels results in a substantial modification of the lateral effective stresses in the adjacent ground. Especially the pouring process of the panel and the fresh concrete pressure causes a partial mobilization of the passive earth pressure and a distinct stress level increase in the upper half of the wall. As a consequence of the increased stresses prior to the pit excavation, up to 15% greater ground and wall movements are predicted. Moreover, the increased stress level due to the installation process of the diaphragm wall leads to substantial higher strut loadings during the excavation of the pit. Copyright © 2006 John Wiley & Sons, Ltd. [source] A new non-invasive ultrasonic method for simultaneous measurements of longitudinal and radial arterial wall movements: first in vivo trialCLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 5 2003Magnus Persson Summary During recent years, the radial movement of the arterial wall has been extensively studied, and measurements of the radial movement are now an important tool in cardiovascular research for characterizing the mechanical properties of the arterial wall. In contrast, the longitudinal movement of vessels has gained little or no attention as it has been presumed that this movement is negligible. With modern high-resolution ultrasound, it can, however, be seen that the intima-media complex of the arterial wall moves not only in the radial direction, but also in the longitudinal direction during pulse-wave propagation. This paper describes a new non-invasive ultrasonic method that is able to measure simultaneously two dimensionally arterial vessel wall movements. The method is demonstrated in a limited in vivo trial. Results from the in vivo trial show that, apart from the well-known radial movement, there is a distinct longitudinal movement in the human common carotid artery with, in this case, the intima-media complex moving substantially as compared with the region of the tunica adventitia. Two-dimensional evaluation of the vessel-wall movements, taking not only the radial movement, but also the longitudinal movement into account, may provide novel information of importance in the evaluation of vessel-wall function. [source] | |||||||||||||