purpose: to study the validity and reliability of subjective refraction, predicted phoropter refraction (ppr) measured by zywave aberrometer, and final surgical plan applied for laser vision correction. methods: this prospective study was conducted on 94 myopic or myopic astigmatic eyes (48 patients) who were candidates for refractive surgery in negah eye hospital from april 2012 to july 2012. ...

A limited seismic investigation of Ball Mountain Dam, an earthen dam near Jamaica, Vermont, was conducted using multiple seismic methods including multi-channel analysis of surface waves (MASW), refraction tomography, and vertical seismic profiling (VSP). The refraction and MASW data were efficiently collected in one survey using a towed land streamer containing vertical-displacement geophones ...

X-Ray Refraction Topography techniques are based on Ultra Small Angle Scattering by micro structural elements causing phase related effects like refraction and total reflection at a few minutes of arc as the refractive index of X-rays is nearly unity. The refraction contrast is several times higher than “true absorption” and results in images of cracks, pores and fibre debonding separations bel...

X-ray refraction-based computer tomography imaging is a well-established method for nondestructive investigations of various objects. In order to perform the 3D reconstruction of the index of refraction, two or more raw computed tomography phase-contrast images are usually acquired and combined to retrieve the refraction map (i.e. differential phase) signal within the sample. We suggest an appr...

X-Ray Refraction Topography techniques are based on Ultra Small Angle Scattering by micro structural elements causing phase related effects like refraction and total reflection at a few minutes of arc as the refractive index of X-rays is nearly unity (1 – 10). The extraordinary contrast of inner surfaces is far beyond absorption effects. Scanning of specimens results in 2D-imaging of closed and...