BACKGROUND Lack of high-fidelity simultaneous measurements of pressure and flow velocity in the aorta has impeded the direct validation of the water-hammer formula for estimating regional aortic pulse wave velocity (AO-PWV1) and has restricted the study of the change of beat-to-beat AO-PWV1 under varying physiological conditions in man. METHODS Aortic pulse wave velocity was derived using two...

In this paper, a nominal sensor placement methodology for leak location in Water Distribution Networks is presented. To reduce the size and the complexity of the optimization problem a clustering technique is combined with the nominal sensor placement methodology. Some of the pressure sensor placement methods for leak detection and location in water distribution networks are based on the pressu...

BACKGROUND Leak after a sleeve gastrectomy (SG) is a severe complication. Risk factors, such as regional ischemia, increased intraluminal pressure, technical failure of the stapling device, and surgeon error, have been reported. OBJECTIVES It was hypothesized that intraoperative hypotension is another risk factor for leak, similar to that reported for colorectal surgery. SETTING Tertiary te...

The Valsalva maneuver was performed by a series of eight patients with chronic Chagas' heart disease who had no current evidence nor past history of heart failure. The fact that all the patients showed recovery of arterial pressure during the latter portion of the period of increased airway pressure and exhibited significant overshoot in pressure in the post-straining period of the Valsalva man...

Twenty novice male weight lifters performed resistance exercises using three different breathing techniques to determine the effects on blood pressure. Systolic and diastolic blood pressures were measured by an automated non-invasive method while subjects performed the single arm curl and double knee extension using the different breathing techniques. Performing the Valsalva manoeuvre (breath-h...

OBJECTIVES During noninvasive positive pressure ventilation (NPPV), the gas leak that commonly occurs around the mask can render NPPV ineffective. We evaluated the effects of gas leak on inspiratory trigger function during NPPV with bilevel pressure and ICU ventilators. In addition, we evaluated the effects of gas leak on fraction of inspired oxygen (Fio(2)) and humidification. METHODS Air le...

A production leak test system using digital holography, Optical Leak Testing (OLT), has been developed for simultaneous gross and fine leak testing of hermetic semiconductor, MEMS and Optoelectronic devices. The technique has also shown the unique capability to leak test ceramic SMC’s on PCBs, even if conformal coated. Many devices are manufactured using welded, brazed or soldered metal lids wi...

Dramatic changes in the shape of pulsatile ascending aortic pressure and flow wave forms occur during the Valsalva maneuver in man. To study these changes, aortic pressure and flow signals were recorded in eight patients using a multisensor catheter. Aortic input impedance was derived during the control, strain and postrelease phases of the Valsalva maneuver. During control, well-defined minima...

Inverse Transient Analysis (ITA) is a powerful approach for leak detection of pipelines. When the pipe transient flow is analyzed in frequency domain the ITA is called Inverse Frequency Response Analysis (IFRA). To implement an IFRA for leak detection, a transient state is initiated in the pipe by fast closure of the downstream end valve. Then, the pressure time history at the valve location is...