 Users may download and print one copy of any publication from the public portal for the purpose of private study or research.  You may not further distribute the material or use it for any profit-making activity or commercial gain  You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.

No abstract

Doppler ultrasonography is routinely used to identify abnormal blood flow. Nevertheless, conventional Doppler can be used to determine only the axial component of blood flow velocity and is angle dependent. A new method of multidimensional angle-independent estimation of flow velocity, called Vector Flow Imaging (VFI), has been proposed. It quantitatively evaluates the true velocity vector's amplitude and direction at any location into a vessel and displays a more intuitive depiction of the flow movements. High frame rate VFI, based on plane wave imaging, allows a detailed dynamic visualization of complex flow by showing even transient events, otherwise undetectable. © 2017 Wiley Periodicals, Inc. J Clin Ultrasound 45:582-588, 2017.

Wall shear stress (WSS) is considered as a key factor for atherosclerosis development. Previous WSS research based on pulsed wave Doppler (PWD) showed limitations in complex flows. To improve accuracy for nonlaminar flow, a commercial ultrasound vector flow imaging (UVFI)‐based WSS calculation is proposed. Errors for PWD are presented theoretically when flow is not laminar. Based on this, simulations of WSS calculations between PWD and UVFI were set up for different turbulent flows. Our simulations show that UVFI has obviously better performance than PWD in WSS calculations. Wall shear stress results in different flow conditions at carotid bifurcations are described.

We theoretically investigate the dually dressed electromagnetically induced transparency, and the multidressed four-wave mixing ͑FWM͒ and six-wave mixing ͑SWM͒ processes in an inverted-Y-type atomic system with Zeeman sublevels. The results show that the Zeeman degeneracy of the dark states can be lifted by the dressing field as its intensity is increased. Moreover, the derived analytical expressions indicate that one can, for example, selectively create secondary dark states on the multi-Zeeman-sublevel dark states ͑by tuning the coupling field͒, distinguish two different types of dark states generated in two FWM processes ͑by properly controlling the coupling field intensity͒, and selectively enhance multi-FWM signals coming from various paths consisting of split Zeeman sublevels ͑by tuning the dressing field͒. The SWM signals can be either enhanced or suppressed by controlling the dressing field.