SPECTROSCOPY OF THE LIGHT FROM THE NIGHT SKY

1930 ◽  
Vol 2 (4) ◽  
pp. 279-290 ◽  
Author(s):  
J. C. McLennan F.R.S. ◽  
H. J. C. Ireton M.A.
Keyword(s):  
High Light ◽  
Light Power ◽  
Moonless Night ◽  
Night Sky ◽  
Auroral Phenomena

This paper describes the development and the construction, with optical details, of a high light power spectrograph suitable for the photography of the spectrum of the light of the moonless night sky and the spectra of auroral displays.Preliminary experiments carried out with it in England and in Canada are described. Typical spectrograms recorded by the instrument are shown.Suggestions for still further increasing the efficiency of the spectrograph are made. The advantages of using the spectrograph described are pointed out. Additional investigations of auroral phenomena, and an extension of those previously made are outlined.

scholarly journals On the spectroscopy of auroral green line radiation

1930 ◽  
Vol 129 (809) ◽  
pp. 31-43 ◽  
Keyword(s):  
High Light ◽  
Green Line ◽  
Light Power ◽  
Line Radiation ◽  
Moonless Night ◽  
Night Sky

In a recent paper by the authors on “Spectroscopy of the Light from the Night Sky,” a description was given of the development and the construction, with optical details, of a high light power spectrograph suitable for photographing the spectrum of the light of the moonless night sky and the spectra of auroral displays. Preliminary experiments were carried out with this instrument in England and in Canada, and a considerable number of spectrograms recorded with the instrument were reproduced and included in the paper.

scholarly journals II.—Bright Clouds on a Dark Night Sky

1883 ◽  
Vol 32 (1) ◽  
pp. 11-36 ◽  
Author(s):  
C. Piazzi Smyth
Keyword(s):  
Small Extent ◽  
Large Telescope ◽  
Dark Night ◽  
Moonless Night ◽  
Night Sky

On a moonless night, whenever clouds of an ordinary elevation in the atmosphere appear upon, or pass across, the star-spangled sky behind them, they exhibit themselves, as a rule, dark, sometimes even black, in comparison therewith. And no wonder, when every part of the open sky from visible star to visible star therein must be lit up to some, though doubtless a very small, extent by the faintest general and cumulative radiance of those myriads and myriads of lesser stars, which only a large telescope can show to be individually existent as actual stellar points of light, but in their aggregate more nearly eternal, and still more constant from age to age, than our gigantic Sun itself.

scholarly journals High-efficiency optogenetic silencing with soma-targeted anion-conducting channelrhodopsins

2017 ◽  
Author(s):  
Mathias Mahn ◽  
Lihi Gibor ◽  
Katayun Cohen-Kashi Malina ◽  
Pritish Patil ◽  
Yoav Printz ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
High Efficiency ◽  
Single Channel ◽  
Ion Homeostasis ◽  
Reversal Potential ◽  
High Light ◽  
Mammalian Brain ◽  
Membrane Targeting ◽  
Power Requirement ◽  
Light Power

AbstractOptogenetic silencing allows time-resolved functional interrogation of defined neuronal populations. However, the limitations of inhibitory optogenetic tools impose stringent constraints on experimental paradigms. The high light power requirement of light-driven ion pumps and their effects on intracellular ion homeostasis pose unique challenges, particularly in experiments that demand inhibition of a widespread neuronal population in vivo. Guillardia theta anion-conducting channelrhodopsins (GtACRs) are promising in this regard, due to their high single-channel conductance and favorable photon-ion stoichiometry. However, GtACRs show poor membrane targeting in mammalian cells, and the activity of such channels can cause transient excitation in the axon due to an excitatory chloride reversal potential in this compartment. Here we address both problems by enhancing membrane targeting and subcellular compartmentalization of GtACRs. The resulting GtACR-based optogenetic tools show improved photocurrents, greatly reduced axonal excitation, high light sensitivity and rapid kinetics, allowing highly efficient inhibition of neuronal activity in the mammalian brain.

Photosynthetic responses of Coffea arabica leaves to a short-term high light exposure in relation to N availability

1997 ◽  
Vol 101 (1) ◽  
pp. 229-239 ◽  
Author(s):  
Jose C. Ramalho ◽  
Thos L. Pons ◽  
Henri W. Groeneveld ◽  
M. Antonieta Nunes
Keyword(s):  
Coffea Arabica ◽  
Light Exposure ◽  
High Light ◽  
N Availability ◽  
Short Term ◽  
Photosynthetic Responses

Change of color appearance due to extremely high light level: corresponding colors under 100 and 3000 cd/m2

2019 ◽  
Vol 2019 (1) ◽  
pp. 320-325 ◽  
Author(s):  
Wenyu Bao ◽  
Minchen Wei
Keyword(s):  
Light Level ◽  
Limited Range ◽  
High Light ◽  
Color Preference ◽  
Color Appearance ◽  
Appearance Model ◽  
Color Matching ◽  
Light Levels ◽  
Appearance Models ◽  
Psychophysical Study

Great efforts have been made to develop color appearance models to predict color appearance of stimuli under various viewing conditions. CIECAM02, the most widely used color appearance model, and many other color appearance models were all developed based on corresponding color datasets, including LUTCHI data. Though the effect of adapting light level on color appearance, which is known as "Hunt Effect", is well known, most of the corresponding color datasets were collected within a limited range of light levels (i.e., below 700 cd/m2), which was much lower than that under daylight. A recent study investigating color preference of an artwork under various light levels from 20 to 15000 lx suggested that the existing color appearance models may not accurately characterize the color appearance of stimuli under extremely high light levels, based on the assumption that the same preference judgements were due to the same color appearance. This article reports a psychophysical study, which was designed to directly collect corresponding colors under two light levels— 100 and 3000 cd/m2 (i.e., ≈ 314 and 9420 lx). Human observers completed haploscopic color matching for four color stimuli (i.e., red, green, blue, and yellow) under the two light levels at 2700 or 6500 K. Though the Hunt Effect was supported by the results, CIECAM02 was found to have large errors under the extremely high light levels, especially when the CCT was low.

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