Photoreceptor optics (9 Ergebnisse)

Zustand: New. In English.

Taschenbuch. Zustand: Neu. Druck auf Anfrage Neuware - Printed after ordering - It is in the receptors of the vertebrate retina that the characteristic visual process - the transduction of radiational energy into physiological activtty of a different kind - takes place. The way these receptors modify or redistribute the incident radiation and thereby control the light ab sorption by the visual pigments they contain, is the central theme of this book. As far back as 1843 Brucke put forward a well-reasoned model for the optics of a receptor, assuming simple ray optics, and it is already some forty-seven years since the dependence of receptor sensitivity on retinal angle of incidence was established experimentally as an important factor in human vision and as one by which the direction of alignment of receptors in the living eye might be determined. But it is to Professor J. M. Enoch, editor and author of several major contributions to this volume, that we owe the first experimental demonstration (in 1961) of the wave-mode propa gation of light in vertebrate visual receptors, as well as the results of some thirty years devoted research concerned with all questions of receptor optics, particularly directional sensitivity and receptor alignment, both for normal vertebrate eyes and for pathologically modified eyes. His work on the latter has opened up a whole range of clinical possibilities.…

Paperback. Zustand: Brand New. reprint edition. 508 pages. 9.25x6.10x1.15 inches. In Stock.

Zustand: New. In English.

Zustand: New.

Taschenbuch. Zustand: Neu. Druck auf Anfrage Neuware - Printed after ordering - The above consideration indicates that at present many of the experi mental facts on PS in animals can be quantitatively explained within the limits of the 'universal' photoreceptor membrane concept. Of course, existence of preferential orientation of the absorbing dipoles in the tubuli of the rhabdomeres can not be totally rejected. We hope that the concept of the 'universal' photoreceptor membrane may serve as the useful instrument when dealing with newly discovered properties of visual cells so that true mechanisms of electrical and optical coupling will be searched for instead of assumptions being made on additional properties of the photoreceptor membrane in every new animal under study. 5. Absorption Spectrum of the Universal Photoreceptor Membrane and Spectral Sensitivity of the Photoreceptor 5. 1 Preliminary Notes It seems nearly self-evident that the absorption spectrum of the pho toreceptor membrane coincides exactly with that of the visual pigment it contains. Hence, the membrane must exhibit three bands of absorp tion - the principal band with its peak within the limits of visible spectrum (or a-peak); the secondary band between 340 and 380 nm (S peak); and the third, protein band, in the ultraviolet (UV) at 280 nm (COLLINS et al. , 1952). The main peak of absorption is located within the range 433-575 nm for retinol-based pigments and between 438 and 620 nm for 3-dehydroretinol-based pigments, the position of Amax de pending on many ecological factors.…

Zustand: Sehr gut. Zustand: Sehr gut | Seiten: 540 | Sprache: Englisch | Produktart: Bücher | The above consideration indicates that at present many of the experi­ mental facts on PS in animals can be quantitatively explained within the limits of the "universal" photoreceptor membrane concept. Of course, existence of preferential orientation of the absorbing dipoles in the tubuli of the rhabdomeres can not be totally rejected. We hope that the concept of the "universal" photoreceptor membrane may serve as the useful instrument when dealing with newly discovered properties of visual cells so that true mechanisms of electrical and optical coupling will be searched for instead of assumptions being made on additional properties of the photoreceptor membrane in every new animal under study. 5. Absorption Spectrum of the Universal Photoreceptor Membrane and Spectral Sensitivity of the Photoreceptor 5. 1 Preliminary Notes It seems nearly self-evident that the absorption spectrum of the pho­ toreceptor membrane coincides exactly with that of the visual pigment it contains. Hence, the membrane must exhibit three bands of absorp­ tion - the principal band with its peak within the limits of visible spectrum (or a-peak); the secondary band between 340 and 380 nm (S­ peak); and the third, protein band, in the ultraviolet (UV) at 280 nm (COLLINS et al. , 1952). The main peak of absorption is located within the range 433-575 nm for retinol-based pigments and between 438 and 620 nm for 3-dehydroretinol-based pigments, the position of Amax de­ pending on many ecological factors.…

Paperback. Zustand: Brand New. 540 pages. 9.53x6.69x1.10 inches. In Stock.

Softcover. Zustand: gut. 1975. Photoreceptor optics. In deutscher Sprache. pages.