Added mass and wave radiation damping for flow-induced rotational vibrations of skinplates of hydraulic gates

One observed vibration mode for Tainter gate skinplates involves the bending of the skinplate about a horizontal nodal line. This vibration mode can be approximated as a streamwise rotational vibration about the horizontal nodal line. Such a streamwise rotational vibration of a Tainter gate skinplate must push away water from the portion of the skinplate rotating into the reservoir and draw water toward the gate over that portion of the skinplate receding from the reservoir. The induced pressure is termed the push-and-draw pressure. In the present paper, this push-and-draw pressure is analyzed using the potential theory developed for dissipative wave radiation problems. In the initial analysis, the usual circular-arc skinplate is replaced by a vertical, flat, rigid weir plate so that theoretical calculations can be undertaken. The theoretical push-and-draw pressure is used in the derivation of the non-dimensional equation of motion of the flow-induced rotational vibrations. Non-dimensionalization of the equation of motion permits the identification of the dimensionless equivalent added mass and the wave radiation damping coefficients. Free vibration tests of a vertical, flat, rigid weir plate model, both in air and in water, were performed to measure the equivalent added mass and the wave radiation damping coefficients. Experimental results compared favorably with the theoretical predictions, thus validating the theoretical analysis of the equivalent added mass and wave radiation damping coefficients as a prediction tool for flow-induced vibrations. Subsequently, the equation of motion of an inclined circular-arc skinplate was developed by incorporating a pressure correction coefficient, which permits empirical adaptation of the results from the hydrodynamic pressure analysis of the vertical, flat, rigid weir plate. Results from in-water free vibration tests on a 1/31-scale skinplate model of the Folsom Dam Tainter gate are used to demonstrate the utility of the equivalent added mass coefficient.

Pulsed-wave tissue Doppler echocardiography for the analysis of fetal cardiac arrhythmias

Rhythm analysis of the fetal heart is hampered by the inability to routinely obtain electrocardiographic recordings of the fetus. Doppler studies of fetal cardiac tissue movements, assessing cardiac movements both qualitatively and quantitatively, have recently been described. We used a conventional high-resolution ultrasound system to obtain rhythm data from pulsed-wave tissue Doppler signals of the fetal heart in normal cardiac rhythm and in a variety of fetal cardiac arrhythmias.

Microvascular response to shock wave application in striated skin muscle

This study aims to quantify by intravital microscopy the microhemodynamic response after extracorporeal shock wave application (ESWA) to the physiologic microcirculation of the mouse dorsal skinfold chamber.

Does a pulsed mode offer advantages over a continuous wave mode for excisional biopsies performed using a carbon dioxide laser?

Animal studies of excisional biopsies have shown less thermal damage when a carbon dioxide (CO(2)) laser (10.6 μm) is used in a char-free (CF) mode than in a continuous-wave (CW) mode. The authors' aim was to evaluate and compare clinical and histopathologic findings of excisional biopsies performed with CW and CF CO(2) laser (10.6 μm) modes.

Radial extracorporeal shock wave therapy (rESWT) induces new bone formation in vivo: results of an animal study in rabbits

The aim of this study was to investigate if radial extracorporeal shock wave therapy (rESWT) induces new bone formation and to study the time course of ESWT-induced osteogenesis. A total of 4000 impulses of radial shock waves (0.16 mJ/mm²) were applied to one hind leg of 13 New Zealand white rabbits with the contralateral side used for control. Treatment was repeated after 7 days. Fluorochrome sequence labeling of new bone formation was performed by subcutaneous injection of tetracycline, calcein green, alizarin red and calcein blue. Animals were sacrificed 2 weeks (n = 4), 4 weeks (n = 4) and 6 weeks (n = 5) after the first rESWT and bone sections were analyzed by fluorescence microscopy. Deposits of fluorochromes were classified and analyzed for significance with the Fisher exact test. rESWT significantly increased new bone formation at all time points over the 6-week study period. Intensity of ossification reached a peak after 4 weeks and declined at the end of the study. New bone formation was significantly higher and persisted longer at the ventral cortex, which was located in the direction to the shock wave device, compared with the dorsal cortex, emphasizing the dose-dependent process of ESWT-induced osteogenesis. No traumata, such as hemorrhage, periosteal detachment or microfractures, were observed by histologic and radiologic assessment. This is the first study demonstrating low-energy radial shock waves to induce new bone formation in vivo. Based on our results, repetition of ESWT in 6-week intervals can be recommended. Application to bone regions at increased fracture risk (e.g., in osteoporosis) are possible clinical indications.

Heterogeneous response of J-wave syndromes to beta-adrenergic stimulation

Inferolateral early repolarization (ER) and Brugada syndrome manifest with J waves. Isoproterenol suppresses recurrent ventricular arrhythmias while reducing J waves in both disorders.