A model for the fibril structure of normal-polarity solar prominences

Solar Physics ◽  
1992 ◽  
Vol 140 (2) ◽  
pp. 289-306 ◽  
Author(s):  
C. D. C. Steele ◽  
E. R. Priest
Keyword(s):  
Solar Prominences ◽  
Fibril Structure ◽  
Normal Polarity

scholarly journals A Fibril Structure Model for Stellar Prominences

1998 ◽  
Vol 167 ◽  
pp. 247-250
Author(s):  
R. Oliver ◽  
J.L. Ballester
Keyword(s):  
Magnetic Flux ◽  
Structure Model ◽  
Centrifugal Acceleration ◽  
Flux Tubes ◽  
Corotation Radius ◽  
Solar Prominences ◽  
Fibril Structure ◽  
Filament Channel ◽  
Magnetic Flux Tubes ◽  
Cool Region

AbstractExtensive observational background exists about the presence of cool material clouds embedded in the stellar coronae of rapidly rotating, late-type stars. Observations of such clouds in HKAqr (Gliese 890) and HD 197890 suggest that the clouds are at heights smaller than the star’s corotation radius and could be looked at as a phenomenon similar to that of solar prominences. Recent observations of solar prominences have reinforced the evidence about their fibril structure made of many long, thin magnetic flux tubes making angles about 25 degrees with the direction of the filament channel, with only the central 10–20% of the magnetic flux tubes filled with cool matter, which can produce a depression at the summits of the flux tubes. Then, assuming a similar structure for the stellar cool clouds, we have looked for the physical characteristics of such stellar prominences, i.e. the size of the flux tube depression, the density, temperature, half-width and supported mass of the cool region, taking into account gravity variation with height and centrifugal acceleration, since such clouds have been detected at great heights within stellar coronae belonging to rapid rotators.

A model for quiescent solar prominences with normal polarity

Solar Physics ◽  
1990 ◽  
Vol 126 (1) ◽  
pp. 117-133 ◽  
Author(s):  
A. W. Hood ◽  
U. Anzer
Keyword(s):  
Solar Prominences ◽  
Normal Polarity

scholarly journals Anti-Parallel β-Hairpin Structure in Soluble Aβ Oligomers of Aβ40-Dutch and Aβ40-Iowa

2021 ◽  
Vol 22 (3) ◽  
pp. 1225
Author(s):  
Ziao Fu ◽  
William E. Van Nostrand ◽  
Steven O. Smith
Keyword(s):  
Amyloid Β ◽  
Amyloid Angiopathy ◽  
Aβ Oligomers ◽  
Dominant Component ◽  
Fibril Structure ◽  
Predominant Component ◽  
Aβ Aggregation ◽  
Aβ Fibrils ◽  
Soluble Aβ Oligomers ◽  
Β Sheet

The amyloid-β (Aβ) peptides are associated with two prominent diseases in the brain, Alzheimer’s disease (AD) and cerebral amyloid angiopathy (CAA). Aβ42 is the dominant component of cored parenchymal plaques associated with AD, while Aβ40 is the predominant component of vascular amyloid associated with CAA. There are familial CAA mutations at positions Glu22 and Asp23 that lead to aggressive Aβ aggregation, drive vascular amyloid deposition and result in degradation of vascular membranes. In this study, we compared the transition of the monomeric Aβ40-WT peptide into soluble oligomers and fibrils with the corresponding transitions of the Aβ40-Dutch (E22Q), Aβ40-Iowa (D23N) and Aβ40-Dutch, Iowa (E22Q, D23N) mutants. FTIR measurements show that in a fashion similar to Aβ40-WT, the familial CAA mutants form transient intermediates with anti-parallel β-structure. This structure appears before the formation of cross-β-sheet fibrils as determined by thioflavin T fluorescence and circular dichroism spectroscopy and occurs when AFM images reveal the presence of soluble oligomers and protofibrils. Although the anti-parallel β-hairpin is a common intermediate on the pathway to Aβ fibrils for the four peptides studied, the rate of conversion to cross-β-sheet fibril structure differs for each.

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