Studies of animal color vision: comments on some important theoretical considerations

1982 ◽  
Vol 60 (11) ◽  
pp. 2968-2970 ◽  
Author(s):  
Craig W. Hawryshyn
Keyword(s):  
Visual System ◽  
Color Vision ◽  
Spectral Sensitivity ◽  
Neural Mechanisms ◽  
Brightness Match ◽  
Wavelength Discrimination ◽  
Innate Behaviors ◽  
Theoretical Considerations

Eliminating brightness as a discriminatory cue is unquestionably the most important factor in animal color vision studies. Accurate descriptions of any species' color vision depends on, first, a determination of spectral sensitivity (electrophysiologically or psychophysically) which can then be used to establish a brightness match between the comparison stimuli and, second, tests of wavelength discrimination. The use of innate responses to investigate animal color vision introduces variables which are not characteristically visual. Since these innate behaviors involve neural mechanisms other than the visual system, they tend to distort the normal characteristics of the species' color vision.

scholarly journals On the determination of step energies. Theoretical considerations and application to an anisotropic Kossel model

2006 ◽  
Vol 39 (4) ◽  
pp. 563-570 ◽  
Author(s):  
M. A. Deij ◽  
J. H. Los ◽  
H. Meekes ◽  
E. Vlieg
Keyword(s):  
Lattice Models ◽  
Single Step ◽  
Spiral Growth ◽  
Growth Theory ◽  
Two Dimensional ◽  
Island Growth ◽  
Growth Step ◽  
Step Flow ◽  
Theoretical Considerations

Steps on surfaces are important in crystal growth theory, as the step free energy determines the two-dimensional nucleation rate, island growth, step flow and spiral growth. In this paper, it is illustrated that in general in lattice models the step energy of a single step cannot be determined directly by counting broken bonds. A new method is proposed that uses the geometry of a step together with the bonding topology, allowing for a straightforward determination of single-step energies for any case. The method is applied to an anisotropic Kossel model.

Man, Monkey, and Blindsight

1998 ◽  
Vol 4 (4) ◽  
pp. 227-230 ◽  
Author(s):  
Tirin Moore ◽  
Hillary R. Rodman ◽  
Charles G. Gross
Keyword(s):  
Visual Cortex ◽  
Visual System ◽  
Primary Visual Cortex ◽  
Visual Function ◽  
Forced Choice ◽  
Neural Mechanisms ◽  
Residual Vision ◽  
Choice Testing

The visual function that survives damage to the primary visual cortex (V1) in humans is often unaccompanied by awareness. This type of residual vision, called “blindsight,” has raised considerable interest because it implies a separation of conscious from unconscious vision mechanisms. The monkey visual system has proven to be a useful model in elucidating the possible neural mechanisms of residual vision and blindsight in humans. Clear similarities, however, between the phenomenology of human and monkey residual vision have only recently become evident. This article summarizes parallels between residual vision in monkeys and humans with damage to V1. These parallels Include the tendency of the remaining vision to require forced-choice testing and the fact that more robust residual vision remains when V1 damage is sustained early in life. NEUROSCIENTIST 4:227–230

Exact determination of gravity stresses in finite elastic slopes: Part I. Theoretical considerations

1983 ◽  
Vol 20 (1) ◽  
pp. 47-54 ◽  
Author(s):  
V. Silvestri ◽  
C. Tabib
Keyword(s):  
Plane Strain ◽  
Half Plane ◽  
Inclination Angle ◽  
Complex Variable ◽  
Earth Pressure ◽  
Exact Distributions ◽  
Exact Determination ◽  
Upper Half Plane ◽  
Theoretical Considerations

The exact distributions of gravity stresses are obtained within slopes of finite height inclined at various angles, −β (β = π/2, π/3, π/4, π/6, and π/8), to the horizontal. The solutions are obtained by application of the theory of a complex variable. In homogeneous, isotropic, and linearly elastic slopes under plane strain conditions, the gravity stresses are independent of Young's modulus and are a function of (a) the coordinates, (b) the height, (c) the inclination angle, (d) Poisson's ratio or the coefficient of earth pressure at rest, and (e) the volumetric weight. Conformal applications that transform the planes of the various slopes studied onto the upper half-plane are analytically obtained. These solutions are also represented graphically.

Determination of the Stress Distribution at the Interface Metal-Oxide: Numerical and Theoretical Considerations

2005 ◽  
Vol 237-240 ◽  
pp. 145-150 ◽  
Author(s):  
Sébastien Garruchet ◽  
A. Hasnaoui ◽  
Olivier Politano ◽  
Tony Montesin ◽  
J. Marcos Salazar ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Stress Distribution ◽  
Oxide Film ◽  
Metal Oxide ◽  
Reaction Kinetics ◽  
Analytical Model ◽  
Equilibrium Thermodynamics ◽  
Theoretical Considerations ◽  
Molecular Dynamics Results

In this paper we give a brief presentation of the approaches we have recently developed on the oxidation of metals. Firstly, we present an analytical model based on non-equilibrium thermodynamics to describe the reaction kinetics present during the oxidation of a metal. Secondly, we present the molecular dynamics results obtained with a code specially tailored to study the oxidation and growth of an oxide film of aluminium. Our simulations present an excellent agreement with experimental results.

scholarly journals Color vision and spectral sensitivity in tunas and marlins.

1981 ◽  
Vol 47 (4) ◽  
pp. 481-485 ◽  
Author(s):  
Gunzo KAWAMURA ◽  
Waichiro NISHIMURA ◽  
Soichi UEDA ◽  
Tooru NISHI
Keyword(s):  
Color Vision ◽  
Spectral Sensitivity

Practical and theoretical considerations for the determination of δ 13 C VPDB values of methylmercury in the environment

2019 ◽  
Vol 33 (13) ◽  
pp. 1122-1136 ◽  
Author(s):  
Philip J.H. Dunn ◽  
Mine Bilsel ◽  
Adnan Şimşek ◽  
Ahmet Ceyhan Gören ◽  
Murat Tunç ◽  
...  
Keyword(s):  
Theoretical Considerations

Visual Acuity Affected by Size Perception Based on Convergence Cue

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 354-354
Author(s):  
H Shinoda ◽  
M Ikeda
Keyword(s):  
Visual Acuity ◽  
Visual System ◽  
Retinal Image ◽  
White Paper ◽  
Retinal Size ◽  
Size Perception ◽  
Convergence Angle ◽  
Threshold Size

Increasing (or decreasing) the convergence angle can shrink (or expand) the perceived size of an object without changing its retinal size (Oyama, 1974 Perception & Psychophysics16 175 – 182). Here we address the question whether such a change in perceived size affects visual acuity. We investigated the effects of perceived size on the legibility of letters, using a telestereoscope consisting of four mirrors to control the observer's convergence angle while keeping the size of the retinal image constant. The targets were photocopies of ordinary Japanese books containing both types of Japanese characters, kana and kanji. The former is a phonetic character and simpler than the latter. Letters were printed in black on white paper. First, we demonstrated that letters do become more legible (illegible) as perceived size expands (shrinks), although their retinal size does not change. Then, we measured the size of the convergence angle at which letters became legible. The ‘threshold’ size of the convergence angle was obtained for several retinal sizes (0.1 to 0.2 deg) of letters, and for kana and kanji, respectively. Four subjects participated in the experiment. The result shows that the threshold convergence angle for legibility decreases as the retinal size of letters decreases, so that the minimum retinal size of legible letters depends linearly on the convergence angle. The results implicate contributions from higher levels of the visual system to the determination of visual acuity.

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