scholarly journals COUNTERACTING THE RETARDING AND INHIBITORY EFFECTS OF STRONG ULTRAVIOLET ON FUCUS EGGS BY WHITE LIGHT

1942 ◽  
Vol 25 (3) ◽  
pp. 391-397 ◽  
Author(s):  
D. M. Whitaker
Keyword(s):  
Ultraviolet Light ◽  
White Light ◽  
Ultraviolet Irradiation ◽  
Wave Length ◽  
Considerable Degree ◽  
Inhibitory Effects ◽  
Degree Of Recovery ◽  
Damaging Effects

1. Strong dosages (20,000–50,000 ergs per mm.2) of ultraviolet light, predominantly of the wave-length 2537 Å, greatly retard and inhibit the development of rhizoids in Fucus eggs irradiated at about 8 hours after fertilization. 2. If white light shines on the eggs after the irradiation by ultraviolet is terminated, the white light causes a considerable degree of recovery from the retarding and inhibiting effects. 3. If strong white light shines on the eggs during the ultraviolet irradiation, its effect is even more marked in protecting the cells from the damaging effects of the ultraviolet.

A novel near-ultraviolet-light excitable Eu3+-doped Sr2LaTaO6 red phosphor for white-light-emitting diodes

Optik ◽  
2021 ◽  
Vol 240 ◽  
pp. 166908
Author(s):  
Qifeng Tang ◽  
Tao Yang ◽  
Haifeng Huang ◽  
Jinqing Ao ◽  
Biyou Peng ◽  
...  
Keyword(s):  
Ultraviolet Light ◽  
White Light ◽  
Light Emitting Diodes ◽  
Red Phosphor ◽  
Light Emitting ◽  
Near Ultraviolet ◽  
White Light Emitting Diodes

The influence of acridine dyes and caffeine on recovery from ultraviolet damage in Eudorina elegans

1975 ◽  
Vol 21 (11) ◽  
pp. 1849-1854 ◽  
Author(s):  
C. L. Kemp ◽  
K. M. Malloy
Keyword(s):  
Dna Synthesis ◽  
Acridine Orange ◽  
Ultraviolet Light ◽  
Ultraviolet Irradiation ◽  
Repair Process ◽  
Repair System ◽  
Acridine Dyes ◽  
Dark Survival ◽  
High Doses ◽  
Ultraviolet Damage

Caffeine and the acridine dyes, acridine orange and acriflavine, were used to examine the repair potential in Eudorina elegans following ultraviolet irradiation. Acridines blocked photoreactivation primarily as a result of absorption of photoreactivating wavelengths, but acridines did not influence dark survival. Therefore, an acridine-sensitive excision–resynthesis–repair process is absent in Eudorina.Caffeine decreased both dark and light survival, the latter only after relatively high doses of ultraviolet light were used for inactivation. The caffeine-sensitive repair process appears to function most actively when the organisms are engaged in DNA synthesis, indicating that a postreplication–repair system exists in Eudorina. However, the data suggest that a repair system not associated with the DNA synthetic phases may also exist.

Effects of ultraviolet light on synchronized Chinese hamster ovary cells; potentiation by hydroxyurea

1977 ◽  
Vol 28 (1) ◽  
pp. 29-48
Author(s):  
K. Burg ◽  
A.R. Collins ◽  
R.T. Johnson
Keyword(s):  
Dna Synthesis ◽  
Ultraviolet Light ◽  
Hela Cells ◽  
Chinese Hamster Ovary ◽  
Ultraviolet Irradiation ◽  
Chromosome Structure ◽  
Chinese Hamster Ovary Cells ◽  
Chinese Hamster ◽  
Ovary Cells

We have examined the effects of hydroxyurea on u.v.-irradiated Chinese hamster CHO-KI cells. Ultraviolet irradiation followed by incubation with hydroxyurea causes only slight disruption of DNA and chromosome structure in CHO-KI cells compared with HeLa cells. There is, however, a clear potentiation by hydroxyurea of the u.v. killing of CHO-KI cells, which is most pronounced at those points in the cycle which are reported to have small DNA precursor pools. This potentiation is reduced when DNA precursors are provided together with hydroxyurea. These data are discussed in terms of an uncoupling of excision and repair DNA synthesis.

Treatment of Juvenile Stroke Using Yamamoto New Scalp Acupuncture (Ynsa) – a Case Report

2007 ◽  
Vol 25 (4) ◽  
pp. 200-202 ◽  
Author(s):  
Toshikatsu Yamamoto ◽  
Thomas Schockert ◽  
Babak Boroojerdi
Keyword(s):  
Case Report ◽  
Treatment Options ◽  
Scalp Acupuncture ◽  
Considerable Degree ◽  
Stroke Patients ◽  
Degree Of Recovery

In Germany, stroke affects approximately 300 children each year. Treatment options for stroke patients, particularly for children, are limited. A case is described of an 18 month old girl with hemiparesis, who showed a considerable degree of recovery over the course of 21 months while receiving Yamamoto New Scalp Acupuncture using soft laser. This may represent a new option for the therapy of such patients.

THE REACTIONS OF THE HOUSEFLY, MUSCA DOMESTICA LINN., TO LIGHT OF DIFFERENT WAVE-LENGTHS

1938 ◽  
Vol 16d (11) ◽  
pp. 307-342 ◽  
Author(s):  
J. W. MacBain Cameron
Keyword(s):  
White Light ◽  
Copper Sulphate ◽  
Wave Length ◽  
Short Wave ◽  
Quantitative Relation ◽  
Copper Sulphate Solution ◽  
Quartz Mercury ◽  
Intensity Changes ◽  
Constant Quality ◽  
Colored Lights

Houseflies were reared on an artificial medium and tested with different wave-lengths of spectral light obtained from a quartz-mercury arc. The spectrum tested extended from λ3022 Å to λ5780 Å, and the lines were made of approximately equal intensity throughout. In addition, λ5461 Å and λ4078 Å were tested at several other intensities. The comparison standard in all cases was white light, obtained from a tungsten-filament, inside-frosted bulb, and filtered through copper sulphate solution. It was of constant quality, and the intensity was varied by changing the size of the bulb and by varying the distance from the bulb to the copper sulphate filter. The lighted areas to which the flies reacted were 5 by 10 mm. On one of these fell a total intensity of colored light of approximately 10.3 microwatts, on the other a range of intensity of white light of from 0.34 to 36.1 μw.Flies to be tested were removed from the breeding cage ten hours before tests began and were kept in darkness until used. Each fly whose record was used in compiling the final results was caused to make ten trips towards the two test lights, and a record was kept of the choice on each trip.A description and discussion of the four different methods found in the literature for conducting experiments of this type, and for analyzing the results, are included. In the first method, the intensity of the test light of a given wave-length is kept constant, while that of the standard light, usually white, is varied until both are equally attractive.The second method involves testing the colored light against a fixed intensity of white and finding the ratio of insects attracted to color. The intensity of white that will give the same ratio of attractiveness when tested against the standard is then determined.In the third method, the two test lights are made equal in intensity, and their relative efficiency is considered to be directly proportional to the number of insects attracted to each.In the last method, the standard is kept fixed in both quality and intensity, and the intensity of the test color is varied until the two are equal in attractiveness.Application of the first three methods to the same data shows that they give results that vary greatly as the intensity changes. Some show that efficiency increases as the intensity increases, while others show a decrease in efficiency with increasing intensity.If the intensities of all colored lights are equal, the three methods give practically the same qualitative results when applied to the same data. That is, a curve of efficiency is found which has its peak at the same wave-length, whatever method is used. Quantitatively, the results given by the three methods differ, so that no definite ratio of attractiveness can be determined between colors.The data obtained were not amenable to analysis by the fourth method, but published results indicate that this is perhaps the best method for determining the quantitative relation between the stimulative efficiencies of light of different colors.The housefly, M. domestica, is much more strongly stimulated by ultraviolet light of wave-length 3656 Å than by any other part of the spectrum examined. The effect decreases, at first rapidly and then more slowly, as the longer wave-lengths are reached; it also decreases on the short-wave side of the peak. The spectrum available extended only as far as λ3022 Å in the ultraviolet, at which point there was still an appreciable attractiveness, apparently greater than that of either yellow or green.Several problems are suggested that require further investigation.

Ultrastructural Changes in Euglena After Ultraviolet Irradiation

1973 ◽  
Vol 13 (3) ◽  
pp. 799-809
Author(s):  
A. MICHAELS ◽  
A. GIBOR
Keyword(s):  
Ultraviolet Light ◽  
Ultraviolet Irradiation ◽  
Euglena Gracilis ◽  
Structural Changes ◽  
Ultrastructural Changes ◽  
Electron Microscopic ◽  
Bleaching Process ◽  
In Cells

The structural changes associated with the ultraviolet-induced bleaching of light-grown cells of Euglena gracilis were investigated. Our light- and electron-microscopic observations of the bleaching process indicate that there is a continuity of plastid structure in cells 5 generations after receiving a bleaching dose of ultraviolet light. There seems to be a continuous dilution of the plastid thylakoids and a decrease in plastid size in the bleaching cells. There also seems to be a change in the position of the plastids in relation to the mitochondria in the bleaching cells. The plastids and possibly the mitochondria are the only organelles which are affected by the ultraviolet irradiation. The continuity of plastids in bleaching cells of Euglena is discussed in relation to the proposed effect of the ultraviolet light.

scholarly journals On the luminosity curves of persons having normal and abnormal colour vision

1913 ◽  
Vol 88 (604) ◽  
pp. 404-428 ◽  
Keyword(s):  
White Light ◽  
Wave Length ◽  
Monochromatic Light ◽  
Absolute Intensity ◽  
White Patch ◽  
The Press ◽  
Colour Sense ◽  
Intimate Relation ◽  
Series Of Experiments ◽  
Pass Through

1. When reading a recent paper before the Royal Society, and also in the Press, Dr. Edridge Green has stated that he can find no connection between the luminosity and the colour sense of persons having either normal or abnormal colour sensations. Since I feel that to allow such a statement to go unchallenged might be interpreted as meaning that no such connection could be shown to exist, I propose in the following paper to place before the Society some of the evidence which indicated that there is in reality a very intimate relation between luminosity and colour sense. The results given include a small part of those which have been obtained in a series of experiments which have occupied the last two years and form part of investigation which is still in progress. The term “luminosity” as used in this paper has the following meaning: Suppose that light from some source, such as the electric arc, is admitted to a spectroscope by means of which a real pure spectrum is produced, and that a slide in the plane in which the spectrum is formed carries a slit of fixed width. Light of sensibly one wave-length, i. e. monochromatic light, will pass through this slit, and by means of a lens placed in the beam of this light an image of the first face of the prism which is used to from the spectrum can be formed on a screen. In this way a monochromatic patch of light is obtained, the brightness of which depends on the nature of the source of light, the width of the collimator slit, the width of the slit placed in the spectrum, which for short will be called the movable slit, and the dimensions of the lenses employed. Further, if alongside this coloured patch is formed a white patch of light produced by light which proceeds from the same source but has not undergone dispersion, and that by some means or other the intensity of this white light is altered till the coloured and white light, measured in any arbitrary units, measure the luminosity of the light of that colour which is passing through the movable slit. Since the unit in which the white light is measured is arbitrary, we are not concerned with the absolute intensity of illumination of the white patch, and may use any device we like to alter the quantity of white light which falls on the screen so long as we are able to measure the ratio of the quantity of light employed in different experiments. It will further be observed that for any given person the measurement of the luminosity of a given coloured light in the spectrum involves the comparsion of the brightness of the coloured patch as it appears to him with the brightness of the white patch as it appears to him.

scholarly journals Emission and absorption in the infra-red spectra of mercury, zinc, and cadmium

1919 ◽  
Vol 95 (669) ◽  
pp. 280-299 ◽  
Keyword(s):  
White Light ◽  
Vapour Pressure ◽  
Wave Length ◽  
Mercury Vapour ◽  
Stimulate Emission ◽  
First Line ◽  
Absorption Bands ◽  
Infra Red ◽  
Partial Parallelism ◽  
Lower Voltage

In a previous paper the writer pointed out that well-marked absorption bands exist in the infra-red region of the spectrum caused by passing white light through non-luminous mercury vapour. These bands occur at λ 1·014, λ 1·129. and λ 1·205, the first and third of these being especially strong. This investigation has since been extended further into the infra-red with mercury vapour, and it has also been repeated with the vapours of zinc and cadmium in place of that of mercury. The results serve to establish at least a partial parallelism in the behaviour of the three metals, the resemblance being most marked in the region of the first line of the series represented by v = (2·5, S)—( m , P), at which wave-length absorption takes place in the case of all three metals with extremely small vapour-pressure. On account of the ease with which the wave-length corresponding to v = (2·5, S)—( m , P) was absorbed, it was suspected that it should be emitted under electronic bombardment. At the suggestion of Prof. McLennan an investigation was undertaken with mercury vapour, in order to determine the speed which electrons must be given in order to stimulate emission of the wave-length λ 1·014. If we apply the quantum relation ve = hv to the frequency of this wave-length, we get V = 1·26 volts. In the experiments which will be described herein, the wave-length λ 1·014 was actually emitted with a voltage as low as 5 volts. There were strong indications that even a lower voltage would suffice to stimulate emission of the wave-length, but under the conditions of the experiment the radiations of this wave-length when emitted were reabsorbed by the intervening layers of mercury vapour.

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