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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."
In the comparative physiology of photoreception by the Protista and
the invertebrates two aspects are emphasized: (1) the diversity of
visual processes in these groups and (2) their bearing upon general
mechanisms of photoreception. Invertebrates have evolved a far
greater variety of adaptations than vertebrates modifications
aiding survival in the remarkably different biotopes they occupy.
The number of species in itself suggests this multiformity; each of
them has peculiarities of its own, in morphology as well as in
physiology and behavior. But these special adaptations are
variations on a few great themes. Although the catalogue of
invertebrate species is immense, the literature concerning them
nearly rivals it in extent-even if one considers only that fraction
dealing with visual physiology. Taxonomy proceeds by grouping the
species, categorizing them in genera, families, orders, and
progressively larger units. Similarly, comparative physiology aims
at an analogous, more or less compre hensive, classification. This
Part A of Volume VII/6, like Part B that follows it, emphasizes the
broad questions that concern groups larger than the individual
species; in some cases these questions have general applicability.
The middle course between approaches that are too specialized and
those that are too general is often elusive, but here we attempt to
follow it. The vast number of special adaptations-probably, as we
have said, as large as the number of species-is beyond the range
even of a handbook."
This text is intended to provide an in-depth, self-contained,
treatment of optical waveguide theory. We have attempted to
emphasize the underlying physical processes, stressing conceptual
aspects, and have developed the mathematical analysis to parallel
the physical intuition. We also provide comprehensive supplementary
sections both to augment any deficiencies in mathematical
background and to provide a self-consistent and rigorous
mathematical approach. To assist in. understanding, each chapter
con centrates principally on a single idea and is therefore
comparatively short. Furthermore, over 150 problems with complete
solutions are given to demonstrate applications of the theory.
Accordingly, through simplicity of approach and numerous examples,
this book is accessible to undergraduates. Many fundamental topics
are presented here for the first time, but, more importantly, the
material is brought together to give a unified treatment of basic
ideas using the simplest approach possible. To achieve such a goal
required a maturation of the subject, and thus the text was
intentionally developed over a protracted period of the last 10
years."
This text is intended to provide an in-depth, self-contained,
treatment of optical waveguide theory. We have attempted to
emphasize the underlying physical processes, stressing conceptual
aspects, and have developed the mathematical analysis to parallel
the physical intuition. We also provide comprehensive supplementary
sections both to augment any deficiencies in mathematical
background and to provide a self-consistent and rigorous
mathematical approach. To assist in. understanding, each chapter
con centrates principally on a single idea and is therefore
comparatively short. Furthermore, over 150 problems with complete
solutions are given to demonstrate applications of the theory.
Accordingly, through simplicity of approach and numerous examples,
this book is accessible to undergraduates. Many fundamental topics
are presented here for the first time, but, more importantly, the
material is brought together to give a unified treatment of basic
ideas using the simplest approach possible. To achieve such a goal
required a maturation of the subject, and thus the text was
intentionally developed over a protracted period of the last 10
years."
Over the past decade or more, the art relating to modern optical
waveguides has evolved as a nighly focused interdis ciplinary
field, so attractive, stimulating and full of far reachin3 promise
that no parallel could be found earlier in other branches of
applied sciences except, perhaps, in solid state electronics and
computer technology. This Proceedings, with a selection of 53
papers and briefs by 96 authors of 16 countries, is of real
internation al dimensions. It is the outgrowth of the International
Symposium held June 20-23, 1983, the first international meeting on
this subject taking place in China. Since almost every country in
the world, Eastern or ~;estern, large or small, has been involved
in the study and promotion of this technological revolution, it is
only natural that China snoula be happy to serve as host country of
the international meeting to promote an interchange of experiences
and iaeas conducive to greater achievements in the future.
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