Plasma Properties in Coronal Holes Derived from Measurements of Minor Ion Spectral Lines and Polarized White Light Intensity

1999 ◽  
Vol 510 (1) ◽  
pp. L63-L67 ◽  
Author(s):  
Ruth Esser ◽  
Silvano Fineschi ◽  
Danuta Dobrzycka ◽  
Shadia R. Habbal ◽  
Richard J. Edgar ◽  
...  
Keyword(s):  
Light Intensity ◽  
White Light ◽  
Coronal Holes ◽  
Spectral Lines ◽  
Plasma Properties ◽  
White Light Intensity

scholarly journals White light intensity stabilization for long term photometric calibrations

2020 ◽  
Vol 238 ◽  
pp. 06015
Author(s):  
João Cachatra ◽  
David Alves ◽  
Manuel Abreu
Keyword(s):  
Light Intensity ◽  
White Light ◽  
Feedback Loop ◽  
Interface Stability ◽  
Intensity Stabilization ◽  
Stability Results ◽  
White Light Intensity

This paper presents an overview of the design of a voice coil based white light intensity stabilization tool. A system is created capable of mechanically stabilizing the fluctuations in a beam of light. This is achieved with a use of a voice coil and simple PID based feedback loop, controlled using a LabVIEW interface. Stability results are shown using Allan deviations curves.

scholarly journals Role of white light intensity and photoperiod during retail in broccoli shelf-life

2020 ◽  
Vol 163 ◽  
pp. 111121 ◽  
Author(s):  
Federico M. Pintos ◽  
Joaquín H. Hasperué ◽  
Ariel R. Vicente ◽  
Luis M. Rodoni
Keyword(s):  
Light Intensity ◽  
Shelf Life ◽  
White Light ◽  
White Light Intensity

The Effects of Linolenic Acid and Extracts of Ricinus Leaf on System I and System II

1970 ◽  
Vol 25 (8) ◽  
pp. 855-859 ◽  
Author(s):  
Seymour Steven Brody
Keyword(s):  
Light Intensity ◽  
Linolenic Acid ◽  
White Light ◽  
Ricinus Communis ◽  
Time Dependent ◽  
Oxygen Production ◽  
Spinach Chloroplasts ◽  
Amperometric Method ◽  
Steady State Rate ◽  
White Light Intensity

The action of extracts of Ricinus communis leaf (RLE) and of linolenic acid (LINO) on System I and System II of corn and spinach chloroplasts were investigated by an amperometric method.RLE induced a time dependent decrease in the rate of oxygen production by corn chloroplasts (half time about one hour) at low white light intensity (900 ergs/cm2 sec.). At high white light intensity (7 x 103 ergs/cm2 sec.) the maximum value of the oxygen gush, V0, was observed to decrease with time in the presence of RLE; the steady state rate of oxygen production, Vm, also decreased under these conditions. The ratio, V0/Vm, decreased immediately upon addition of RLE, then increased with time. The effect of RLE on System I was much more rapid than on System II. In less than one hour all activity of System I disappeared.At high white light intensity addition of 1.6 x 10-4 M LINO to spinach chloroplasts induced a time dependent decrease of V0 and increase of Vm. The latter effect is indicative of uncoupling of phosphorylation. The ratio V0/Vm decreased both with time of incubation and concentration of LINO. On the other hand, at concentrations less than 10-4 M, LINO has little effect on System I.It is concluded that both RLE and LINO may be acting on the reaction center of System II. It appears that RLE contains a fraction that specifically acts to immediately reduce the number of System I reaction centers.

Pyruvate-dependent diauxic growth of Rhodospirillum rubrum in light

1982 ◽  
Vol 152 (3) ◽  
pp. 1175-1187
Author(s):  
D Solaiman ◽  
R L Uffen
Keyword(s):  
Light Intensity ◽  
Phase I ◽  
Phase Ii ◽  
White Light ◽  
Growth Response ◽  
Rhodospirillum Rubrum ◽  
Radiant Energy ◽  
Diauxic Growth ◽  
Lag Period ◽  
White Light Intensity

When Rhodospirillum rubrum mutant C was first exposed to radiant energy after long-term anaerobic dark growth, the cells often exhibited a diauxic growth response. This happened with pyruvate in the medium and when cultures were exposed to a less-than-growth-saturating white light intensity of about 6,460 lx. Under the growth-saturating light condition, mutant C photometabolized and growth was not affected by Na hypophosphite, an inhibitor of pyruvate fermentation. In lower intensity light, in which diauxie occurred, initial (phase I) growth occurred by fermentation of Na pyruvate and was sensitive to Na hypophosphite inhibition. Once pyruvate was depleted, phase I growth stopped, the bacteriochlorophyll content of the cells began to increase from about 3 nmol/mg of protein, and growth finally resumed phototrophically (phase II). The lag period and phase II growth were influenced by radiant energy. By changing the white light intensity from 2,150 to 753 lx between experiments, the duration of both the lag period and the generation time of cells in phase II growth increased. Diauxic growth was pyruvate dependent. It occurred with pyruvate even if malate, a photometabolizable substrate, was added to the growth medium. Moreover, the biphasic growth response was reversible. It was observed not only with R. rubrum mutant C grown cells photosynthetically, but also when other strains of R. rubrum were placed in pyruvate medium under lowered light conditions. Only R. rubrum S1 did not exhibit the typical pyruvate-dependent diauxic growth response.

scholarly journals Light-responsive expression atlas reveals the effects of light quality and intensity in Kalanchoë fedtschenkoi, a plant with crassulacean acid metabolism

GigaScience ◽  
2020 ◽  
Vol 9 (3) ◽  
Author(s):  
Jin Zhang ◽  
Rongbin Hu ◽  
Avinash Sreedasyam ◽  
Travis M Garcia ◽  
Anna Lipzen ◽  
...  
Keyword(s):  
Light Intensity ◽  
White Light ◽  
Crassulacean Acid Metabolism ◽  
Light Quality ◽  
Acid Metabolism ◽  
Easy Access ◽  
Cam Plants ◽  
A Genome ◽  
Acid Accumulation ◽  
Expression Atlas

Abstract Background Crassulacean acid metabolism (CAM), a specialized mode of photosynthesis, enables plant adaptation to water-limited environments and improves photosynthetic efficiency via an inorganic carbon-concentrating mechanism. Kalanchoë fedtschenkoi is an obligate CAM model featuring a relatively small genome and easy stable transformation. However, the molecular responses to light quality and intensity in CAM plants remain understudied. Results Here we present a genome-wide expression atlas of K. fedtschenkoi plants grown under 12 h/12 h photoperiod with different light quality (blue, red, far-red, white light) and intensity (0, 150, 440, and 1,000 μmol m–2 s–1) based on RNA sequencing performed for mature leaf samples collected at dawn (2 h before the light period) and dusk (2 h before the dark period). An eFP web browser was created for easy access of the gene expression data. Based on the expression atlas, we constructed a light-responsive co-expression network to reveal the potential regulatory relationships in K. fedtschenkoi. Measurements of leaf titratable acidity, soluble sugar, and starch turnover provided metabolic indicators of the magnitude of CAM under the different light treatments and were used to provide biological context for the expression dataset. Furthermore, CAM-related subnetworks were highlighted to showcase genes relevant to CAM pathway, circadian clock, and stomatal movement. In comparison with white light, monochrome blue/red/far-red light treatments repressed the expression of several CAM-related genes at dusk, along with a major reduction in acid accumulation. Increasing light intensity from an intermediate level (440 μmol m−2 s−1) of white light to a high light treatment (1,000 μmol m–2 s–1) increased expression of several genes involved in dark CO2 fixation and malate transport at dawn, along with an increase in organic acid accumulation. Conclusions This study provides a useful genomics resource for investigating the molecular mechanism underlying the light regulation of physiology and metabolism in CAM plants. Our results support the hypothesis that both light intensity and light quality can modulate the CAM pathway through regulation of CAM-related genes in K. fedtschenkoi.

scholarly journals The photographic efficiency of heterogeneous light

1921 ◽  
Vol 100 (703) ◽  
pp. 109-113 ◽  
Keyword(s):  
Absorption Coefficient ◽  
White Light ◽  
Photographic Plate ◽  
Silver Halide ◽  
Radiant Energy ◽  
Spectral Lines ◽  
Photographic Emulsion ◽  
Mercury Vapour ◽  
Mercury Vapour Lamp

There are some sources of illumination which are much more active photographically than others, and one of the most active of all artificial sources is the mercury vapour lamp. The energy of the radiation from this lamp is concentrated in a comparatively few spectral lines, and most of these are in that region of the spectrum which is the region of greatest absorption by the silver halide grains of which the photographic emulsion is composed. This, in itself, may be the complete explanation of the intense photographic activity of this particular illuminant, but the question arises as to whether the explanation is, in part, merely the fact that the light is concentrated into a few wave-lengths, apart altogether from any consideration of the absorption coefficient. In other words, a given quantity of radiant energy absorbed in the grains may give a greater photographic effect when it is all of one frequency than when it is a complex radiation such as white light. The object of the present paper is to discuss this question in the light of recent researches on the photographic plate.

White-light solar corona structure observed by naked eye and processed images

2020 ◽  
Vol 495 (2) ◽  
pp. 2170-2178 ◽  
Author(s):  
Vojtech Rušin ◽  
Paul Prikryl ◽  
Emil A Prikryl
Keyword(s):  
Solar Wind ◽  
White Light ◽  
High Speed ◽  
Geomagnetic Storms ◽  
Interplanetary Space ◽  
Coronal Holes ◽  
Human Vision ◽  
Naked Eye ◽  
Wide Range ◽  
White Light Corona

ABSTRACT Light and dark adaptation and luminance contrast enhancement are well-known characteristics of human vision that allow us to observe a wide range of light intensity not fully captured in standard camera images. The naked-eye observations of total eclipses, some recorded with spectacular detail in artists’ paintings, reveal structure that is consistent with images obtained by telescopes equipped with recording media. The actual shape of the corona during a total eclipse depends not only on the phase of the solar cycle but, as can be simply demonstrated, also on the day-to-day variability and spatial distribution of coronal intensity that is determined by solar surface magnetic fields, including the locations of coronal holes that are the sources of high-speed solar wind causing geomagnetic storms. The latter were very similar for the eclipses in 1932, 1994, and 2017, which is the main reason why the naked-eye observations, as well as the processed images (1994 and 2017), of the white-light corona displayed very similar shapes. White-light corona image processing is a useful technique to enhance the contrast to observe fine-scale structure that is consistent with the physics of the solar atmosphere shaped by the magnetic field drawn out into the interplanetary space by solar wind.

scholarly journals Observations of Correlated White‐Light and Extreme‐Ultraviolet Jets from Polar Coronal Holes

1998 ◽  
Vol 508 (2) ◽  
pp. 899-907 ◽  
Author(s):  
Y.‐M. Wang ◽  
N. R. Sheeley, Jr. ◽  
D. G. Socker ◽  
R. A. Howard ◽  
G. E. Brueckner ◽  
...  
Keyword(s):  
White Light ◽  
Extreme Ultraviolet ◽  
Coronal Holes

scholarly journals The Large-Scale Structure of the Corona

1980 ◽  
Vol 5 ◽  
pp. 549-556
Author(s):  
Jack B. Zirker
Keyword(s):  
Solar Corona ◽  
White Light ◽  
Large Scale ◽  
Dimensional Space ◽  
Coronal Holes ◽  
Solar Limb ◽  
Active Regions ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Fast Wind

The solar corona serves as a prototype of the outer atmospheres of all cool stars. Because of its nearness we can study this prototype in more detail than any other example. Considerable progress has been made recently in understanding how the large scale structure of the solar corona controls the genesis of the solar wind and the distribution of slow and fast wind streams throughout the three-dimensional space surrounding the sun. In this review we will discuss some of the progress made in this field during the last few years. We will emphasize the observational data and the inferences that can be made more or less directly from them. T. Holzer will discuss the theoretical aspects of stellar wind acceleration in another paper in this symposium.The large scale structures of the solar corona consist essentially of three kinds: streamers, active regions and coronal holes. Figure 1 is a familiar photograph of the solar corona, obtained in white light at the total eclipse of 30 June 1973 by the High Altitude Observatory. The streamers are the petal-like structures extending out from the black lunar limb. They taper to narrow radial spikes that have been traced out as far as 10-12 solar radii (Keller, 1979). Daily measurements of the white light corona at the Mauna Loa Observatory (Hundhausen et al. 1979) and the Pic-du-Midi Observatory (Dollfus et al., 1977) since 1965 show that the streamers are fan-shaped structures that may extend 120° in solar longitude. We see them in various perspectives at the solar limb.

Sign in / Sign up

Export Citation Format

Share Document