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Base curve radius (BCR) or simply base curve (BC) is the measure of an important parameter of a lens in optometry. On a spectacle lens, it is the flatter curvature of the front surface. On a contact lens it is the curvature of the back surface and is sometimes referred to as the back central optic radius (BCOR). Typical values for a contact ...
Diameter and base curve radius. The parameters specified in a contact lens prescription may include: Brand name; Material; Base curve radius (BC, BCR) Diameter (D, OAD) Optical power in diopters (dpt) Center thickness (CT) Prescriptions for contact lenses and glasses may be similar but are not interchangeable.
An osculating curve from a given family of curves is a curve that has the highest possible order of contact with a given curve at a given point; for instance a tangent line is an osculating curve from the family of lines, and has first-order contact with the given curve; an osculating circle is an osculating curve from the family of circles ...
A consequence of the definition is that the restriction of the 2-form ω = dα to a hyperplane in ξ is a nondegenerate 2-form. This construction provides any contact manifold M with a natural symplectic bundle of rank one smaller than the dimension of M. Note that a symplectic vector space is always even-dimensional, while contact manifolds ...
The tangent at any point of the curve is perpendicular to the generating line irrespective of the mounting distance of the gears. Thus the line of the force follows the generating line, and is thus tangent to the two base circles, and is known as the line of action (also called pressure line or line of contact).
A yield curve inversion is defined as when interest rates flip on short- and long-term U.S. Treasury bonds, with short-term yields exceeding those on longer-term bonds. Other Indicators of a Recession
Deep blue ray refers the radius of curvature and the red line segment is the sagitta of the curve (black). In optics and especially telescope making, sagitta or sag is a measure of the glass removed to yield an optical curve. It is approximated by the formula
The recession of 2020, was the shortest and steepest in U.S. history and marked the end of 128 months of expansion. Key Predictors, Indicators and Warning Signs of a Recession