Clinician definition, a physician or other qualified person who is involved in the treatment and observation of living patients, as distinguished from one engaged in research. See more. Dictionary.com
In geometry, the foci (/ËfoÊsaÉª/ ; singular focus) are a pair of special points with reference to which any of a variety of curves is constructed. For example, foci can be used in defining conic sections, the four types of which are the circle, ellipse, parabola, and hyperbola. In addition, foci are used to define the Cassini oval and the Cartesian oval.
Cones reside mostly in the central portion of the retina, and allow us to perceive fine visual detail and color. 1  Image courtesy of Robert N. Fariss, Ph.D., chief of the NEI Biological Imaging Core, and Ann H. Milam, Ph.D., former professor in the Department of Ophthalmology at the University of Washington.