PRINCIPAL POINT
\pɹˈɪnsɪpə͡l pˈɔ͡ɪnt], \pɹˈɪnsɪpəl pˈɔɪnt], \p_ɹ_ˈɪ_n_s_ɪ_p_əl p_ˈɔɪ_n_t]\
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Two p's situated on the optical axis or the line connecting the centers of curvature of the various refracting surfaces of a compound dioptric system, and so related that the final emergent ray bears the same relation to the second (or posterior) principal p. (E) that the initial or incident ray would bear to the first (or anterior) principal p. (E) after having undergone refraction through a single refracting surface of determinate curvature situated at E.
By Smith Ely Jelliffe
Word of the day
Proto Oncogene Proteins c erbB 2
- cell surface protein-tyrosine kinase that is found to be overexpressed in significant number adenocarcinomas. It has extensive homology can heterodimerize EGF EPIDERMAL GROWTH FACTOR), 3 receptor (RECEPTOR, 3) and the 4 receptor. Activation of erbB-2 receptor occurs during heterodimer formation with a ligand-bound erbB family members. EC 2.7.11.-.