OBJECTIVES To reanalyze randomized controlled trials on the use of umbilical artery Doppler velocimetry in high-risk pregnancies and determine which high-risk pregnancies benefit from the use of Doppler velocimetry. METHODS Searching Medline, the Cochrane Library and Embase we found 13 randomized controlled trials on the use of Doppler velocimetry in high-risk pregnancies. Of these, six inclu...

The introduction of Doppler velocimetry to obstetrics offered a noninvasive and safe imaging modality of indirectly assessing the fetal and uteroplacental circulation. Obstetric Doppler ultrasound plays an important role in detecting Intra Uterine Growth Restriction (IUGR). The early diagnosis of IUGR with the help of abnormal flow patterns in umbilical, uterine and middle cerebral arteries usi...

In order to increase containment efficiency and reduce energy consumption, an inclined quad-vortex range hood (IQV range hood) was developed and tested by experimental methods. The flow structure was observed by a laser-assisted flow visualization technique and laser Doppler velocimetry (LDV). Leakage characteristics were measured by the tracer gas (sulfur hexafluoride) detection method. By arr...

In this work, we present the excitation strategy, experimental setup, and results of an implementation of krypton tagging velocimetry (KTV) as applied to an underexpanded jet of three mixtures. We demonstrate that the KTV technique can be employed with gas mixtures of relatively low krypton concentration (0.5% Kr/99.5% N2) and conclude that the KTV technique shows promise as a velocimetry diagn...