A continuous spectrum of a white-light flare

Solar Physics ◽  
1982 ◽  
Vol 80 (1) ◽  
pp. 113-127 ◽  
Author(s):  
Eijiro Hiei

1974 ◽  
Vol 20 (7) ◽  
pp. 1015-1021 ◽  
Author(s):  
E. H. Schwartzel ◽  
J. J. Cooney

Micrococcus roseus is killed by exposure to a continuous spectrum of white light (3000 ft-c (32 292 lm/m2)) in the presence of air and the dye, toluidine blue. Comparison of rates of photodynamic killing for log and stationary phase cells and for two pigmentation mutants indicated that photosensitivity could not be correlated with amount of carotenoid or with carotenoid-chromophore length. Moreover, cells grown in medium containing diphenylamine (DPA) did not contain significant quantities of colored carotenoids; they were not as sensitive to photodynamic killing as fully pigmented cells. Photodynamic killing was accompanied by selective release of magnesium and calcium and by release of UV-absorbing material. In the absence of added photosensitizer, M. roseus, the two mutants, or DPA-inhibited cells were not killed when exposed to white light at intensities as high as 22 000 ft-c (236 806 lm/m2) for as long as 9 h, and cells did not release UV-absorbing material. Under these conditions M. roseus and the yellow mutant did not release as much magnesium or calcium as when subjected to photodynamic killing, but DPA-grown cells leaked sodium, magnesium, and calcium. These observations are consistent with several suggestions: (i) carotenoids do not serve as photochemical buffers in M. roseus; (ii) growth in medium containing DPA or mutations leading to altered pigmentation change membrane organization leading to altered photosensitivity; (iii) M. roseus has an efficient repair mechanism which renders it resistant to photodynamic killing unless an exogenous photosensitizer is present.



1967 ◽  
Vol 28 ◽  
pp. 177-206
Author(s):  
J. B. Oke ◽  
C. A. Whitney

Pecker:The topic to be considered today is the continuous spectrum of certain stars, whose variability we attribute to a pulsation of some part of their structure. Obviously, this continuous spectrum provides a test of the pulsation theory to the extent that the continuum is completely and accurately observed and that we can analyse it to infer the structure of the star producing it. The continuum is one of the two possible spectral observations; the other is the line spectrum. It is obvious that from studies of the continuum alone, we obtain no direct information on the velocity fields in the star. We obtain information only on the thermodynamic structure of the photospheric layers of these stars–the photospheric layers being defined as those from which the observed continuum directly arises. So the problems arising in a study of the continuum are of two general kinds: completeness of observation, and adequacy of diagnostic interpretation. I will make a few comments on these, then turn the meeting over to Oke and Whitney.



1994 ◽  
Vol 144 ◽  
pp. 541-547
Author(s):  
J. Sýkora ◽  
J. Rybák ◽  
P. Ambrož

AbstractHigh resolution images, obtained during July 11, 1991 total solar eclipse, allowed us to estimate the degree of solar corona polarization in the light of FeXIV 530.3 nm emission line and in the white light, as well. Very preliminary analysis reveals remarkable differences in the degree of polarization for both sets of data, particularly as for level of polarization and its distribution around the Sun’s limb.



1994 ◽  
Vol 144 ◽  
pp. 82
Author(s):  
E. Hildner

AbstractOver the last twenty years, orbiting coronagraphs have vastly increased the amount of observational material for the whitelight corona. Spanning almost two solar cycles, and augmented by ground-based K-coronameter, emission-line, and eclipse observations, these data allow us to assess,inter alia: the typical and atypical behavior of the corona; how the corona evolves on time scales from minutes to a decade; and (in some respects) the relation between photospheric, coronal, and interplanetary features. This talk will review recent results on these three topics. A remark or two will attempt to relate the whitelight corona between 1.5 and 6 R⊙to the corona seen at lower altitudes in soft X-rays (e.g., with Yohkoh). The whitelight emission depends only on integrated electron density independent of temperature, whereas the soft X-ray emission depends upon the integral of electron density squared times a temperature function. The properties of coronal mass ejections (CMEs) will be reviewed briefly and their relationships to other solar and interplanetary phenomena will be noted.



2000 ◽  
Vol 179 ◽  
pp. 197-200
Author(s):  
Milan Minarovjech ◽  
Milan Rybanský ◽  
Vojtech Rušin

AbstractWe present an analysis of short time-scale intensity variations in the coronal green line as obtained with high time resolution observations. The observed data can be divided into two groups. The first one shows periodic intensity variations with a period of 5 min. the second one does not show any significant intensity variations. We studied the relation between regions of coronal intensity oscillations and the shape of white-light coronal structures. We found that the coronal green-line oscillations occur mainly in regions where open white-light coronal structures are located.



1965 ◽  
Vol 8 (4) ◽  
pp. 323-347
Author(s):  
Robert Goldstein ◽  
Benjamin RosenblÜt

Electrodermal and electroencephalic responsivity to sound and to light was studied in 96 normal-hearing adults in three separate sessions. The subjects were subdivided into equal groups of white men, white women, colored men, and colored women. A 1 000 cps pure tone was the conditioned stimulus in two sessions and white light was used in a third session. Heat was the unconditioned stimulus in all sessions. Previously, an inverse relation had been found in white men between the prominence of alpha rhythm in the EEG and the ease with which electrodermal responses could be elicited. This relation did not hold true for white women. The main purpose of the present study was to answer the following questions: (1) are the previous findings on white subjects applicable to colored subjects? (2) are subjects who are most (or least) responsive electrophysiologically on one day equally responsive (or unresponsive) on another day? and (3) are subjects who are most (or least) responsive to sound equally responsive (or unresponsive) to light? In general, each question was answered affirmatively. Other factors influencing responsivity were also studied.





2016 ◽  
Vol 25 (3) ◽  
pp. 289-293
Author(s):  
Anda Carmen Achim ◽  
Stefan Cristian Vesa ◽  
Eugen Dumitru

Background: Diagnosis of portal hypertensive gastropathy (PHG) is based on endoscopic criteria. I-scan technology, a new technique of virtual chromoendoscopy, increases the diagnostic accuracy for lesions in the gastrointestinal tract. Aim: To establish the role of i-scan endoscopy in the diagnosis of PHG. Method: In this prospective study, endoscopic examination was conducted first by using white light and after that i-scan 1 and i-scan 2 technology in a group of 50 consecutive cirrhotic patients. The endoscopic diagnostic criteria for PHG followed the Baveno criteria. The interobserver agreement between white light endoscopy and i-scan endoscopy was determined using Cohen’s kappa statistics. Results: Forty-five of the 50 patients met the diagnostic criteria for PHG when examined by i-scan endoscopy and 39 patients were diagnosed with PHG by white light endoscopy. The strength of agreement between the two methods for the diagnosis of PHG was moderate (k=0.565; 95%CI 0.271-0.859; p<0.001). I-scan 1 classified the mosaic pattern better than classic endoscopy; i-scan 2 described better the red spots. Conclusion: I-scan examination increased the diagnostic sensitivity of PHG. The diagnostic criteria (mosaic pattern and red spots) were easier to observe endoscopically using i-scan than in white light.Abbreviations: FICE: Fuji Intelligent chromoendoscopy; GAVE: gastric antral vascular ectasia; NBI: narrow band imaging; PHG: portal hypertensive gastropathy; PHT: portal hypertension; UGIB: upper gastrointestinal bleeding.



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