scholarly journals Recurrent coronal jets observed by SDO/AIA

2021 ◽  
Vol 21 (10) ◽  
pp. 262
Author(s):  
Yan-Jie Zhang ◽  
Qing-Min Zhang ◽  
Jun Dai ◽  
Zhe Xu ◽  
Hai-Sheng Ji
Keyword(s):  
Magnetic Reconnection ◽  
Initial Velocity ◽  
Coronal Loop ◽  
Solar Surface ◽  
Gas Pressure ◽  
The Other ◽  
Viscous Drag ◽  
Multiwavelength Observations

Abstract In this paper, we carried out multiwavelength observations of three recurring jets on 2014 November 7. The jets originated from the same region at the edge of AR 12205 and propagated along the same coronal loop. The eruptions were generated by magnetic reconnection, which is evidenced by continuous magnetic cancellation at the jet base. The projected initial velocity of jet2 is ∼402 km s−1. The accelerations in the ascending and descending phases of jet2 are not consistent, the former is considerably larger than the value of g ⊙ at the solar surface, while the latter is lower than g ⊙. There are two possible candidates of extra forces acting on jet2 during its propagation. One is the downward gas pressure from jet1 when it falls back and meets with jet2. The other is the viscous drag from the surrounding plasma during the fast propagation of jet2. As a contrast, the accelerations of jet3 in the rising and falling phases are constant, implying that the propagation of jet3 is not significantly influenced by extra forces.

scholarly journals Magnetoconvection Patterns in Rotating Convection Zones

1991 ◽  
Vol 130 ◽  
pp. 37-56
Author(s):  
Paul H. Roberts
Keyword(s):  
Convection Zone ◽  
Solar Surface ◽  
Giant Cells ◽  
Conclusive Evidence ◽  
The Other ◽  
The Sun ◽  
Solar Convection Zone ◽  
Solar Convection ◽  
Entire Thickness ◽  
Convective Motions

AbstractIn addition to the well-known granulation and supergranulation of the solar convection zone (the “SCZ”), the presence of so-called “giant cells” has been postulated. These are supposed span the entire thickness of the SCZ and to stretch from pole to pole in a sequence of elongated cells like a “cartridge belt” or a bunch of “bananas” strung uniformly round the Sun. Conclusive evidence for the existence of such giant cells is still lacking, despite strenuous observational efforts to find them. After analyses of sunspot motion, Ribes and others believe that convective motions near the solar surface occurs in a pattern that is the antithesis of the cartridge belt: a system of “toroidal” or “doughnut” cells, girdling the Sun in a sequence that extends from one pole to the other. Galloway, Jones and Roberts have recently tried to meet the resulting theoretical challenge, with the mixed success reported in this paper.

scholarly journals Holes in the Solar Corona

1975 ◽  
Vol 68 ◽  
pp. 19-21
Author(s):  
W. M. Glencross
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Solar Corona ◽  
Field Component ◽  
Solar Surface ◽  
Field Direction ◽  
The Other ◽  
Flux Tubes ◽  
Sequence Of Events

SummaryBabcock (1961) outlined the sequence of events which takes place in the Sun's atmosphere during a solar cycle. Magnetic field loops, having preferred directions, emerge from the solar surface and thereafter merge with neighbouring loops to produce more extended structures. Although flux tubes emerge with a strong E-W field component, having the field direction reversed from one side of the equator to the other, there is a tendency for the longer loops produced by merging to have a significant N-S alignment (Hansen et al., 1972).

Differential Boundary-Layer Separation Effects in the Flow over a Rotating Cylinder

1969 ◽  
Vol 73 (702) ◽  
pp. 524-528 ◽  
Author(s):  
R. T. Griffiths ◽  
C. Y. Ma
Keyword(s):  
Boundary Layer ◽  
Flow Velocity ◽  
Lift Force ◽  
Boundary Layer Separation ◽  
Rotating Cylinder ◽  
The Other ◽  
Viscous Drag ◽  
Magnus Force ◽  
Rotating Body ◽  
Rotating Surface

When a rotating body is placed in a stream of fluid the viscous drag of the rotating surface moving forward on one side and backwards on the other causes the flow velocity to be lower and hence the pressure on the forward-moving side higher than on the backward-moving side, thus giving a lateral (lift) force L in the direction shown in Fig. 1. This force, known as the Magnus force, is well known to engineers and also to sportsmen. In tennis, for example, top spin is used to swerve a fast ball downwards so that it falls within the required area of play, while in golf the Magnus force causes the all too familiar sliced shot when the club is drawn across the ball at impact.

THE CONCENTRATIONS OF OIL IN SEA WATER RESULTING FROM NATURAL AND CHEMICALLY INDUCED DISPERSION OF OIL SLICKS

1977 ◽  
Vol 1977 (1) ◽  
pp. 381-385 ◽  
Author(s):  
D. Cormack ◽  
J.A. Nichols
Keyword(s):  
Surface Tension ◽  
Oil Recovery ◽  
Oil Spills ◽  
Sea Water ◽  
The Other ◽  
Viscous Drag ◽  
Two Dimensional ◽  
Drag Forces ◽  
Chemically Induced ◽  
Low Toxicity

ABSTRACT Results are presented on the factors relating to the dissipation of oil spills at sea, including evaporation, emulsion formation, spreading, and natural dispersion into the water column. For Ekofisk oil, 20% evaporates in about 7.5 hours and, while emulsion formation is as rapid as for Kuwait crude, the resulting viscosity is low and insufficient to allow interference with the natural spreading and dispersion rates. Spreading has two components. One is controlled by surface tension-viscous drag forces and the other is wind-induced. Together they contribute to the two dimensional dissipation of the oil so that subsequent oil concentrations in the sea are of necessity, low. These concentrations were measured for naturally dispersing and chemically dispersed slicks. The chemically-dispersed slicks were of two kinds. One was previously weathered for three hours, the other was of controlled thickness and was dispersed immediately upon being laid. Resulting concentrations of oil in the sea are low and of short duration compared with those required to give observable effects in laboratory toxicity studies. No significant deleterious effects were found to result from the dispersion of oil slicks at sea using low toxicity dispersant chemicals; also it was noted that, in any case, substantial quantities of oil can be expected to enter the sea before oil recovery operations can be mounted.

Manufacture of Penetrating-Pores Metals by High Gas Pressure

1991 ◽  
Vol 251 ◽  
Author(s):  
Yoshihiro Okumoto ◽  
A. Takata ◽  
K. Ishizaki
Keyword(s):  
Copper Powder ◽  
Permeability Coefficient ◽  
Gas Pressure ◽  
The Other ◽  
New Method ◽  
Porous Metals

ABSTRACTOpen porous metals can be made by direct hot isostatic press (HIP) treatment on a cold isostatic pressed body. In this work, porous metals with uniaxially penetrating pores were produced using a modified HIP method.Penetrating pores from one surface to the other surface are useful for filter applications, and were produced by forcing pressurized gas to travel through samples by alternating the HiPping pressure during sintering.In this experiment, copper powder was used. Samples produced with this new method have higher permeability coefficient than those produced by the normal HIP method.

Gas Pressure Dependence of Photon Emission Accompanying Fracture of Polycrystalline MgO in Nitrogen

2006 ◽  
Vol 317-318 ◽  
pp. 313-316 ◽  
Author(s):  
Tadashi Shiota ◽  
Yasuo Toyoshima ◽  
Kouichi Yasuda ◽  
Yohtaro Matsuo
Keyword(s):  
Pressure Dependence ◽  
Room Temperature ◽  
Photon Emission ◽  
Gas Discharge ◽  
Gas Pressure ◽  
The Other ◽  
Experimental Conditions ◽  
Infrared Photon ◽  
Gas Pressures

The photon emission accompanying fracture of a polycrystalline MgO was investigated at room temperature under N2 gas pressures from 10-4 to 105 Pa. At fracture, the ultraviolet, visible and infrared photon emissions instantaneously increased, and then rapidly decreased in most of the experimental conditions. However, in a N2 gas pressure of around 100 Pa, their peak counts lasted for about 10 milliseconds, and the amount of the UV photon emission was fifteen times larger than those obtained in the other N2 gas pressures. This abrupt increment in the emission was explained by the luminescence due to N2 gas discharge according to the classical Townsend’s theory. In conclusion, the photon emission accompanying fracture of a polycrystalline MgO mainly originated from the excited defects as reported by the authors previously, but the N2 gas discharge had a supplementary effect on the emission around a specific N2 gas pressure.

Purification of Prothrombin by Means of Adsorption Onto Al(OH)3 in the Presence of Cd++ Ions

1975 ◽  
Author(s):  
P. P. Devilee ◽  
H. C. Hemker
Keyword(s):  
Amino Acid ◽  
Initial Velocity ◽  
Coagulation Factors ◽  
The Other ◽  
Terminal Amino Acid ◽  
Simple Method ◽  
Factor Ii ◽  
Final Yield ◽  
Terminal Amino ◽  
Generating System

A simple method for the purification of prothrombin is based on the phenomenon that in the presence of 1 mM CdSO4, Al(OH)3 (1.3% w/v) completely adsorbs the coagulation factors VII, IX, and X from normal plasma but adsorbs factor II for about 50% only. Column chromatography is necessary only once. A 750-fold purification is obtained at a 24% yield. The product is indistinguishable from that obtained by the method of Kisiel and Hanahan (Biochim. Biophys. Acta 304, 103-113, 1973) as judged by amino acid composition, N-terminal amino acid (alanin) molecular weight (73,000) or immunological properties. Comparison of the two preparations in a thrombin generating system shows that although the final yield of thrombin from a given amount of prothrombin in both preparations is the same, the initial velocity of thrombin formation from our preparation is comparable to that of native prothrombin, whereas the other preparation is converted significantly slower.This phenomenon may be related to the loss of γ-carboxyl glutamic acid residues during the purification procedure as described by Kisiel and Hanahan.

Transport and exchange diffusion of l-tryptophan in Ehrlich cells

1961 ◽  
Vol 200 (5) ◽  
pp. 1063-1068 ◽  
Author(s):  
John A. Jacquez
Keyword(s):  
Amino Acid ◽  
Initial Velocity ◽  
The Other ◽  
Preliminary Loading ◽  
Exchange Diffusion ◽  
Diaminobutyric Acid ◽  
Low Concentrations ◽  
Ehrlich Ascites ◽  
Ehrlich Ascites Cells ◽  
High Concentrations

The initial velocity of uptake of l-tryptophan by Ehrlich ascites cells can be explained as the sum of two processes: diffusion and an active transport that shows a saturation effect. Azaserine, l-2,4 diaminobutyric acid, l-histidine, and l-leucine, at low concentrations, increase the initial velocity of uptake of l-tryptophan but compete with l-tryptophan at high concentrations. Preliminary loading of the cells with glycine decreases the initial tryptophan flux: preliminary loading of the ascites cells with azaserine or tryptophan markedly increases the initial flux of uptake of the other amino acid.

scholarly journals Observations of the Association of Prominences and the Surrounding Corona

1998 ◽  
Vol 167 ◽  
pp. 37-40
Author(s):  
Raymond N. Smartt ◽  
Zhenda Zhang ◽  
Vladimir S. Airapetian ◽  
Ira S. Kim
Keyword(s):  
High Temperature ◽  
Emission Line ◽  
Magnetic Reconnection ◽  
Coronal Loop ◽  
Observational Evidence ◽  
Coronal Emission ◽  
Flare Loop ◽  
Active Prominence ◽  
Coronal Region

AbstractEmission-line coronal images in Fe XIV (530.3 nm) and FeX (637.5 nm) show faint enhancements at the location of quiescent prominences. Such enhancements can appear in the outer portions of a prominence, similar to the high-temperature sheath surrounding prominences as inferred from UV and EUV observations. The observational evidence supports the interpretation that this enhanced coronal emission is due to energy carried by the prominence threads and dissipated in the adjacent coronal region. Also, observed coronal loop interactions involving partial magnetic reconnection have associated Hα structures. These structures can have the appearance of an active prominence, similar to those typically observed in post flare loop systems. It appears that the association of such active prominences with the adjacent corona is fundamentally different from that of quiescent prominences. The observations indicate that these types of active prominences arise simply as a consequence of reconnection processes in the corona itself.

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