Determination of effect on dark adaptation of varying intensities of illumination in ready rooms. (Bur. Med. Surg., 1943; Publ. Bd., No. 22977.).

1946 ◽  
Author(s):  
R. H. Lee
Keyword(s):  
Dark Adaptation

scholarly journals The determination of dark adaptation time using electroretinography in conscious Miniature Schnauzer dogs

2007 ◽  
Vol 8 (4) ◽  
pp. 409 ◽  
Author(s):  
Hyung-Ah Yu ◽  
Man-Bok Jeong ◽  
Shin-Ae Park ◽  
Won-Tae Kim ◽  
Se-Eun Kim ◽  
...  
Keyword(s):  
Dark Adaptation ◽  
Adaptation Time

scholarly journals Threshold and adaptation in Phycomyces. Their interrelation and regulation by light.

1984 ◽  
Vol 84 (1) ◽  
pp. 119-132 ◽  
Author(s):  
P Galland ◽  
V E Russo
Keyword(s):  
Growth Rate ◽  
Dark Adaptation ◽  
Type Strain ◽  
Wild Type Strain ◽  
Light Sensitivity ◽  
Growth Conditions ◽  
Continuous Illumination ◽  
Growth Responses ◽  
Wild Type

The absolute light sensitivity of Phycomyces sporangiophores was determined by analyzing the intensity dependence of the phototropic bending rate and of the light growth and dark growth responses to step changes of the intensity. We found that the different methods give approximately the same results for the wild-type strain, as well as for several behavioral mutants with defects in the genes madA, madB, and madC. A crucial factor in the determination of thresholds is the light intensity at which the strains grow during the 4 d after inoculation and prior to the experiment. When the wild-type strain grows in the dark, its threshold for the bending rate is 10(-9) W X m-2, compared with 2 X 10(-7) W X m-2 when it is grown under continuous illumination. Further, the maximal bending rate is twice as high in dark-grown strains. This phenomenon is further complicated by the fact that the diameter and growth rate of the sporangiophores also depend on the illumination conditions prior to the experiment: light-grown sporangiophores have an increased diameter and an increased growth rate compared with dark-grown ones. Some of the behavioral mutants, however, are indifferent to this form of light control. Another factor that is controlled by the growth conditions is adaptation: the kinetics of dark adaptation are slower in light-grown sporangiophores than in dark-grown ones. We found empirically a positive correlation between the slower dark adaptation constant and the threshold of the bending rate, which shows that the two underlying phenomena are functionally related.

Electroretinographic determination of dark adaptation functions of children exposed to phototherapy as infants

1974 ◽  
Vol 85 (1) ◽  
pp. 25-29 ◽  
Author(s):  
Velma Dobson ◽  
Lorrin A. Riggs ◽  
Einar R. Siqueland
Keyword(s):  
Dark Adaptation

Galactic orbits of stars

1966 ◽  
Vol 25 ◽  
pp. 93-97
Author(s):  
Richard Woolley
Keyword(s):  
Globular Cluster ◽  
Potential Field ◽  
High Velocity ◽  
Velocity Vector ◽  
Variable Stars ◽  
The Sun ◽  
Proper Motions ◽  
Rr Lyrae ◽  
The Galaxy

It is now possible to determine proper motions of high-velocity objects in such a way as to obtain with some accuracy the velocity vector relevant to the Sun. If a potential field of the Galaxy is assumed, one can compute an actual orbit. A determination of the velocity of the globular clusterωCentauri has recently been completed at Greenwich, and it is found that the orbit is strongly retrograde in the Galaxy. Similar calculations may be made, though with less certainty, in the case of RR Lyrae variable stars.

Distance to SN 1987A and the LMC

1999 ◽  
Vol 190 ◽  
pp. 549-554
Author(s):  
Nino Panagia
Keyword(s):  
Angular Size ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Light Curves ◽  
Distance Modulus ◽  
Absolute Size ◽  
Sn 1987A

Using the new reductions of the IUE light curves by Sonneborn et al. (1997) and an extensive set of HST images of SN 1987A we have repeated and improved Panagia et al. (1991) analysis to obtain a better determination of the distance to the supernova. In this way we have derived an absolute size of the ringRabs= (6.23 ± 0.08) x 1017cm and an angular sizeR″ = 808 ± 17 mas, which give a distance to the supernovad(SN1987A) = 51.4 ± 1.2 kpc and a distance modulusm–M(SN1987A) = 18.55 ± 0.05. Allowing for a displacement of SN 1987A position relative to the LMC center, the distance to the barycenter of the Large Magellanic Cloud is also estimated to bed(LMC) = 52.0±1.3 kpc, which corresponds to a distance modulus ofm–M(LMC) = 18.58±0.05.

International determination of the total motion of the pole

1961 ◽  
Vol 13 ◽  
pp. 29-41
Author(s):  
Wm. Markowitz
Keyword(s):  
Secular Motion ◽  
The Future

A symposium on the future of the International Latitude Service (I. L. S.) is to be held in Helsinki in July 1960. My report for the symposium consists of two parts. Part I, denoded (Mk I) was published [1] earlier in 1960 under the title “Latitude and Longitude, and the Secular Motion of the Pole”. Part II is the present paper, denoded (Mk II).

Time and Latitude in South Africa

1972 ◽  
Vol 1 ◽  
pp. 27-38
Author(s):  
J. Hers
Keyword(s):  
South Africa ◽  
Cape Town ◽  
Astronomical Observations ◽  
Royal Observatory ◽  
The Republic ◽  
Astronomical Determination ◽  
Limited Accuracy ◽  
Better Than

In South Africa the modern outlook towards time may be said to have started in 1948. Both the two major observatories, The Royal Observatory in Cape Town and the Union Observatory (now known as the Republic Observatory) in Johannesburg had, of course, been involved in the astronomical determination of time almost from their inception, and the Johannesburg Observatory has been responsible for the official time of South Africa since 1908. However the pendulum clocks then in use could not be relied on to provide an accuracy better than about 1/10 second, which was of the same order as that of the astronomical observations. It is doubtful if much use was made of even this limited accuracy outside the two observatories, and although there may – occasionally have been a demand for more accurate time, it was certainly not voiced.

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