نتایج جستجو برای: spectral doppler

تعداد نتایج: 208190  

Journal: :Optics express 2014
Haiyun Xia Xiankang Dou Mingjia Shangguan Ruocan Zhao Dongsong Sun Chong Wang Jiawei Qiu Zhifeng Shu Xianghui Xue Yuli Han Yan Han

Temperature detection remains challenging in the low stratosphere, where the Rayleigh integration lidar is perturbed by aerosol contamination and ozone absorption while the rotational Raman lidar is suffered from its low scattering cross section. To correct the impacts of temperature on the Rayleigh Doppler lidar, a high spectral resolution lidar (HSRL) based on cavity scanning Fabry-Perot Inte...

2003
Abraham Loeb B. Scott Gaudi

Upcoming space-based photometric satellites offer the possibility of detecting continuum flux variability at the micromagnitude (mmag) level. We show that the Doppler flux variability induced by the reflex motion of stars due to planetary companions has an amplitude of , where K is the reflex radial velocity amplitude (3 a)K/c and is the logarithmic slope of the source spectral flux in the obse...

2017
Jose M Ortiz-Rodriguez Luis Anel-Lopez Patricia Martín-Muñoz Mercedes Álvarez Gemma Gaitskell-Phillips Luis Anel Pedro Rodríguez-Medina Fernando J Peña Cristina Ortega Ferrusola

Testicular function is particularly susceptible to vascular insult, resulting in a negative impact on sperm production and quality of the ejaculate. A prompt diagnosis of testicular dysfunction enables implementation of appropriate treatment, hence improving fertility forecasts for stallions. The present research aims to: (1) assess if Doppler ultrasonography is a good tool to diagnose stallion...

Journal: :Journal of biomedical optics 2017
Bingyao Tan Zohreh Hosseinaee Kostadinka Bizheva

The variability in the spatial orientation of retinal blood vessels near the optic nerve head (ONH) results in imprecision of the measured Doppler angle and therefore the pulsatile blood flow (BF), when those parameters are evaluated using Doppler OCT imaging protocols based on dual-concentric circular scans. Here, we utilized a dense concentric circle scanning protocol and evaluated its precis...

Journal: :Journal of ultrasound in medicine : official journal of the American Institute of Ultrasound in Medicine 2002
Andrze Ustymowicz Jaroslaw Krejza Zofia Mariak

OBJECTIVE To show an artifact related to color Doppler flow imaging of the orbit. METHODS Three patients with strongly reflective structures in the orbit were selected from those routinely referred by clinicians for color Doppler ultrasonography of the orbit. Gray scale and color flow images were obtained with a 7.5-MHz linear array probe for a region with strongly reflective structures. A sp...

Journal: :Circulation 1985
H Dittrich P Nicod B Hoit N Dalton D Sahn

We studied the value of two-dimensional Doppler echocardiographic color flow mapping for identifying normal transvalve flow profiles and valve malfunction in 20 patients with Björk-Shiley prosthetic valves. Seven patients had Björk-Shiley prosthetic valves in the aortic position alone, seven in the mitral position, and six had prosthetic valves in both the aortic and mitral positions. In 10 pat...

2010
Kirk W Beach Robert O Bergelin Daniel F Leotta Jean F Primozich P Max Sevareid Edward T Stutzman R Eugene Zierler

INTRODUCTION Serial monitoring of patients participating in clinical trials of carotid artery therapy requires noninvasive precision methods that are inexpensive, safe and widely available. Noninvasive ultrasonic duplex Doppler velocimetry provides a precision method that can be used for recruitment qualification, pre-treatment classification and post treatment surveillance for remodeling and r...

1996
Jaakko Talvitie Gordon Povey

The performance of a Doppler estimation scheme for CDMA land mobile satellite systems under realistic channel conditions is studied by computer simulation. The scheme can be applied in Doppler compensation of the received signals, to aid in the code acquisition under the severe Doppler conditions offered by the satellite channel. The proposed scheme is based on a continuous-wave pilot carrier p...

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