Light alteration caused by snow and its importance to subnivean rodents

1972 ◽  
Vol 50 (7) ◽  
pp. 1023-1032 ◽  
Author(s):  
L. N. Evernden ◽  
W. A. Fuller
Keyword(s):  
Mammalian Species ◽  
Red Light ◽  
Visible Spectrum ◽  
Ground Level ◽  
Color Temperature ◽  
Late Winter ◽  
Behavioral Reactions ◽  
Light Levels ◽  
Blue Radiation ◽  
Light Avoidance

Silicon photocells placed in three habitats before snowfall revealed that light levels in the subnivean environment are inversely related to thickness of snow cover. Under 15 cm of snow in the fall, detectable light was sharply reduced. Under midwinter snow depths of 30 to 50 cm no light was detectable by the photocells used and color temperature readings showed greatest penetration to ground level in the red end of the visible spectrum. Sexual maturation of laboratory females of Clethrionomys gapperi was stimulated by white and blue radiation and increased daylength during late winter. Red light was not stimulatory, even over a 16-h day. As in other mammalian species, male voles did not appear to be as strongly photosensitive as females. Captive voles, given a choice of lights of different wavelength and total darkness, exhibited light-avoidance. Thus, the physiological and behavioral reactions of voles to the modified subnivean light regime ensure that subnivean winter breeding does not occur in this species. Factors controlling maturation of microtines that do breed under snow ought to be investigated.

scholarly journals Colourfulness as a possible measure of object proximity in the larval zebrafish brain

2020 ◽  
Author(s):  
Philipp Bartel ◽  
Filip K Janiak ◽  
Daniel Osorio ◽  
Tom Baden
Keyword(s):  
Dynamic Range ◽  
Red Light ◽  
Visible Spectrum ◽  
Visual Ecology ◽  
Neural Representation ◽  
Spectral Tuning ◽  
Fish Brain ◽  
Visual Neurons ◽  
Zebrafish Brain ◽  
Larval Zebrafish

The encoding of light increments and decrements by separate On- and Off- systems is a fundamental ingredient of vision, which supports the detection of edges in space and time and makes efficient use of limited dynamic range of visual neurons [1]. Theory predicts that the neural representation of On- and Off-signals should be approximately balanced, including across an animals’ full visible spectrum. Here we find that larval zebrafish violate this textbook expectation: in the fish brain, UV-stimulation near exclusively gives On-responses, blue/green-stimulation mostly Off- responses, and red-light alone elicits approximately balanced On- and Off-responses (see also [2–4]). We link these findings to zebrafish visual ecology, and suggest that the observed spectral tuning boosts the encoding of object “colourfulness”, which correlates with object proximity in their underwater world [5].

scholarly journals Snow-Creep Pressure on Masts

1989 ◽  
Vol 13 ◽  
pp. 154-158 ◽  
Author(s):  
Jan Otto Larsen ◽  
Jens Laugesen ◽  
Krister Kristensen
Keyword(s):  
Snow Cover ◽  
Snow Depth ◽  
Ground Level ◽  
Close Correlation ◽  
Late Winter ◽  
Pressure Measurements ◽  
Snow Pack ◽  
Snow Layer ◽  
Western Norway ◽  
Snow Pressure

Snow-pressure measurements have been carried out on two masts at the NGI avalanche station in Grasdalen, western Norway. These two tubular masts have diameters of 0.22 and 0.42 m, respectively, and are situated on a 25° slope with a deep snow cover. The most important conclusions are that within a homogeneous snow-pack there is a close correlation between snow-creep pressure and the product of acceleration due to gravity, g, density, ρ, and snow depth, H, that the highest pressures are recorded in late winter when the snow-pack is at the 0°C isothermal, and finally that a weak 0° C isothermal snow layer at ground level appears to increase snow pressure.

scholarly journals Diverse Cell Types, Circuits, and Mechanisms for Color Vision in the Vertebrate Retina

2019 ◽  
Vol 99 (3) ◽  
pp. 1527-1573 ◽  
Author(s):  
Wallace B. Thoreson ◽  
Dennis M. Dacey
Keyword(s):  
Color Vision ◽  
Ganglion Cells ◽  
Color Perception ◽  
Visible Spectrum ◽  
Cell Types ◽  
Photon Flux ◽  
Low Light ◽  
Vertebrate Retina ◽  
Light Levels ◽  
Synaptic Interactions

Synaptic interactions to extract information about wavelength, and thus color, begin in the vertebrate retina with three classes of light-sensitive cells: rod photoreceptors at low light levels, multiple types of cone photoreceptors that vary in spectral sensitivity, and intrinsically photosensitive ganglion cells that contain the photopigment melanopsin. When isolated from its neighbors, a photoreceptor confounds photon flux with wavelength and so by itself provides no information about color. The retina has evolved elaborate color opponent circuitry for extracting wavelength information by comparing the activities of different photoreceptor types broadly tuned to different parts of the visible spectrum. We review studies concerning the circuit mechanisms mediating opponent interactions in a range of species, from tetrachromatic fish with diverse color opponent cell types to common dichromatic mammals where cone opponency is restricted to a subset of specialized circuits. Distinct among mammals, primates have reinvented trichromatic color vision using novel strategies to incorporate evolution of an additional photopigment gene into the foveal structure and circuitry that supports high-resolution vision. Color vision is absent at scotopic light levels when only rods are active, but rods interact with cone signals to influence color perception at mesopic light levels. Recent evidence suggests melanopsin-mediated signals, which have been identified as a substrate for setting circadian rhythms, may also influence color perception. We consider circuits that may mediate these interactions. While cone opponency is a relatively simple neural computation, it has been implemented in vertebrates by diverse neural mechanisms that are not yet fully understood.

scholarly journals STUDIES ON PNEUMONIA VIRUS OF MICE (PVM)

1946 ◽  
Vol 83 (1) ◽  
pp. 43-64 ◽  
Author(s):  
Frank L. Horsfall ◽  
Edward C. Curnen
Keyword(s):  
Neutralizing Antibodies ◽  
Animal Species ◽  
Pulmonary Infection ◽  
Mammalian Species ◽  
Late Winter ◽  
Atypical Pneumonia ◽  
Specific Antibody Response ◽  
Cotton Rat ◽  
Cotton Rats ◽  
Circulating Antibodies

The results of neutralization tests with PVM and serum obtained from numerous animal species indicate that antibodies agaiust this virus were present in the blood of all mammalian species tested, as not in that of fowls, and that their incidence in various species was widely different. They indicate, also, that in certain species, particularly the cotton rat, there were marked seasonal variations in the incidence of such antibodies; in the late winter and spring the incidence was much higher than during the summer and fall seasons. Cotton rats and hamsters which did not possess neutralizing antibodies against PVM were susceptible to manifest pulmonary infection with this virus, irrespective of the effects of previous experiments upon them, whereas those which possessed such antibodies were immune. It is suggested that circulating antibodies against PVM were present as a result of preceding infection with a latent virus; either PVM or an agent closely related to it in antigenic composition. Appropriate non-specific stimuli, e.g. the intranasal injection of suspensions of normal chick embryos, induced the development of neutralizing antibodies against PVM with significantly greater frequency in each of three species than occurred in control animals. Materials derived from patients with primary atypical pneumonia yielded results almost identical to those obtained with normal chick embryo suspensions. It is suggested that such materials, like the other non-specific stimuli employed, were effective in evoking a specific antibody response, because they unbalanced an equilibrium which previously existed between animal host and latent pneumotropic virus.

scholarly journals Adjustable light source for low light level with nearly constant correlated color temperature

2022 ◽  
Vol 2149 (1) ◽  
pp. 012016
Author(s):  
Z F Wu ◽  
L Li ◽  
C H Dai ◽  
Y F Wang ◽  
Q T Cheng ◽  
...  
Keyword(s):  
Light Source ◽  
Spectral Distribution ◽  
Light Level ◽  
Color Temperature ◽  
Spectral Radiance ◽  
Integrating Sphere ◽  
Spectral Difference ◽  
Low Light ◽  
Light Levels ◽  
Variable Aperture

Abstract Low light level (LLL) calibration becomes more and more important since the rapid growth of remote sensing. The spectral radiance at normal higher light levels can be calibrated with good accuracy, while LLL spectral radiance cannot. If an adjustable light source can be designed at nearly constant correlated color temperature (CCT) covering several orders of magnitude, low light level spectral radiance can be obtained with the help of a photodetector. Whether or not the spectral distribution of an integrating sphere based light source is nearly constant is investigated. By adjusting the diameter of the variable aperture between the integrating sphere and tungsten lamp, the spectral radiance can be varied over 6 orders of magnitude. However, the relative spectrum in the red region increases notably when the spectral radiance is decreased to 1/100000. If the spectral radiance is decreased further, the spectral difference can be more than 300% and CCT decreases more than 250 K. By using baffles and another integrating sphere, low light level radiation source at nearly constant spectral distribution is obtained. The variation of CCT is less than 50 K over 6 orders of magnitude.

The roles of filters in the photophores of oceanic animals and their relation to vision in the oceanic environment

1985 ◽  
Vol 225 (1238) ◽  
pp. 63-97 ◽  
Keyword(s):  
Sea Water ◽  
External Surface ◽  
Red Light ◽  
Visible Spectrum ◽  
Transmission Band ◽  
Spectral Absorption ◽  
Good Match ◽  
Mesopelagic Zone ◽  
Light Filters ◽  
Colour Match

In many of the photophores found in deep-sea fishes and invertebrates, light filters containing pigments lie between the tissues that generate light and the sea. The loss of light within such filters has been measured throughout the visible spectrum for a variety of animals. These filters differ greatly in their spectral absorption characteristics and do not all contain the same pigments. All those from ventral photophores have a transmission band in the blue corresponding to the daylight that penetrates best into oceanic waters. For two fishes it is shown that the light generated inside their photophores is a relatively poor spectral match for the ambient submarine daylight while the light emitted into the sea, after passing through the filters, is a good match. For a third fish a similar improvement in ‘colour match’ is brought about not by passing the light through a filter containing pigments but by reflecting the light into the sea by a blue mirror. All these observations support the hypothesis that the ventral photophores are used for camouflage. Malacosteus niger Ayres 1848 is an oceanic fish which emits red light from a large suborbital photophore. The red light generated inside the photophore is largely absorbed by a coloured filter over its external surface which transmits only a band of light of wavelengths around 700 nm. This is a waveband which is heavily absorbed by oceanic sea water. It is shown, however, that animals that can emit and are sensitive to such far-red light will have very great advantages in being able to see without being seen. The ranges over which such red light can be useful for vision are, however, relatively small. The nature of the pigments found in these various photophores is discussed. It is also calculated that the intensities of penetrating daylight are such that visual acuity could be fairly good down to considerable depths in the mesopelagic zone.

The optical characters of Antimonite

1907 ◽  
Vol 14 (66) ◽  
pp. 199-203 ◽  
Author(s):  
A. Hutchinson
Keyword(s):  
Wave Length ◽  
Red Light ◽  
Visible Spectrum ◽  
Verbal Communication ◽  
Orthorhombic Symmetry ◽  
Long Wave ◽  
Visual Observations

In a paper communicated to this Society in March, 1903, it was shown that antimonite is fairly transparent to radiations of long wave-length and that its behaviour between crossed nicols is consistent with orthorhombic symmetry. At the same time it was pointed out that it would be of interest to determine the wave-lengths of the radiations transmitted and the principal indices of refraction of antimonlte for these radiations. On undertaking this investigation it was soon found that antimonite was quite sufficiently transparent to the rays at the extreme red end of the visible spectrum to enable visual observations to, be made, and in a verbal communication to the Society on March 22, 1904, it was stated that the indices of refraction for red light were 4.129 for rays vibrating parallel to the axis Z and 3.873 for rays vibrating parallel to the axis X.

scholarly journals Antagonistic Components of the Late Receptor Potential in the Barnacle Photoreceptor Arising from Different Stages of the Pigment Process

1973 ◽  
Vol 62 (1) ◽  
pp. 105-128 ◽  
Author(s):  
S. Hochstein ◽  
B. Minke ◽  
P. Hillman
Keyword(s):  
Strong Dependence ◽  
Red Light ◽  
Receptor Potential ◽  
Photoreceptor Cells ◽  
The Other ◽  
Light Levels ◽  
Early Receptor Potential ◽  
Late Receptor Potential ◽  
A Cell ◽  
532 Nm

The late receptor potential (LRP) recorded in barnacle photoreceptor cells exhibits, at high light levels, a strong dependence on the color of the stimulus and of the preceding adaptation. Most strikingly, red illumination of a cell previously adapted to blue light results in a depolarization which may last for up to 30 min after the light goes off, while blue illumination of a cell previously adapted to red light cuts short this extended depolarization or prevents its induction by a closely following red light. Comparison of the action spectra for the stimulus-coincident LRP and for the extended depolarization and its curtailment with those previously measured for the early receptor potential (ERP) confirms that these phenomena derive from the same bi-stable pigment as the ERP. The stimulus-coincident response and the extended depolarization appear to arise from substantial activation of the stable 532 nm state of the pigment, while activation of the stable 495 state depresses or prevents the extended depolarization and probably also depresses the stimulus-coincident response. Since either process can precede the other, with mutually antagonistic effects, one is not simply the reversal of the other; they must be based on separate mechanisms. Furthermore, comparison with ERP kinetics shows that both processes involve mechanisms additional to the pigment changes, as seen in the ERP. A model is proposed and discussed for the LRP phenomena and their dependences on wavelength, intensity, and duration of illumination based on excitor-inhibitor interactions.

Response of carp (Cyprinus carpio) horizontal cells to heterochromatic flicker photometry

2006 ◽  
Vol 23 (3-4) ◽  
pp. 437-440 ◽  
Author(s):  
MARLISON JOSÉ L. DE AGUIAR ◽  
DORA FIX VENTURA ◽  
MANOEL DA SILVA FILHO ◽  
JOHN MANUEL DE SOUZA ◽  
ROGÉRIO MACIEL ◽  
...  
Keyword(s):  
Horizontal Cell ◽  
Red Light ◽  
Green Light ◽  
Physiological Solution ◽  
Horizontal Cells ◽  
Xenon Lamp ◽  
Constant Amplitude ◽  
Light Levels ◽  
Electrophysiological Recordings ◽  
Heterochromatic Flicker Photometry

The objective of the present work was to determine the interaction of cone inputs in the response of horizontal cells using heterochromatic flicker photometry (HFP). Intracellular electrophysiological recordings were made in horizontal cells of isolated retinae of carp maintained in physiological solution, with the receptor side up. Sharp glass microelectrodes filled with 3 M KCl solution with resistances between 100 and 120 MΩ were used. Stimuli comprised six cycles of two 6-Hz sinusoidal light waves in counterphase adjusted for the same number of quanta: a green light (550 nm) from a monochromator with a Xenon lamp and an LED red light (628 nm). The stimulation program consisted of 10 steps with the 550-nm wave at constant amplitude, while the 628-nm wave varied in increments of 10% up to 100%, followed by another 10 steps with the 628-nm wave at constant amplitude while the 550-nm wave varied in increments of 10% up to 100%. We recorded responses from four different horizontal cell classes: H1 (monophasic, broadband, n = 37), H2 (biphasic, red-green color-opponent, n = 13), and H3 (biphasic, blue-yellow color-opponent, n = 2) cone horizontal cells; and RH (monophasic, broadband, n = 3) rod horizontal cells. H1 and RH horizontal cells showed a similar cancellation point at a heterochromatic mixture consistent with mixed inputs from 630- and 550-nm cones. No cancellation point was found for the H2 cell class. Fish H1 cells add cone inputs and signal “luminance” in light levels appropriate for cone stimulation. The same occurs with RH cells, which also signal “luminance,” but in light levels appropriate for rod work. For both cell classes there is an HFP cancellation point occurring at a combination of 628-nm and 550-nm lights in opposing phase that leads to the cancellation of the cell's response. No cancellation was found for H2 and H3 cells, which are the chromatically opponent horizontal cells in lower vertebrates.

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