Residential Density Patterns in London—Any Role Left for the Exponential Density Gradient?

1991 ◽  
Vol 23 (7) ◽  
pp. 1007-1024 ◽  
Author(s):  
G R Crampton
Keyword(s):  
Density Gradient ◽  
Residential Density ◽  
Exponential Density

The Negative Exponential Density Gradient and the Standard Radius: Mathematical and Empirical Relationships

1981 ◽  
Vol 13 (9) ◽  
pp. 1059-1065 ◽  
Author(s):  
D M Manson
Keyword(s):  
Density Gradient ◽  
Urban Areas ◽  
Urban Population ◽  
Empirical Relationships ◽  
Use Of Data ◽  
Exponential Density ◽  
Population Distributions ◽  
Negative Exponential ◽  
The Relationship ◽  
The Empirical Analysis

This paper demonstrates for urban areas a direct relationship between the summary measures of centrography and the slope parameter of the negative exponential density gradient model. Starting with some basic assumptions about the form of urban population distributions, a mathematical relationship between the methods is derived by applying the centrographic technique to an exponentially distributed urban population. By use of data from a diverse sample of cities that vary in population, region, area, and time of data collection, the relationship is tested empirically. The results of the empirical analysis are compared with the predictions of the derived relationship, and the causes of differences between them are discussed.

Activated Prominences; Mechanisms for Activation and Eruption

1979 ◽  
Vol 44 ◽  
pp. 307-313
Author(s):  
D.S. Spicer
Keyword(s):  
Pressure Gradient ◽  
Density Gradient ◽  
Current Density ◽  
Convective Instability ◽  
Tearing Mode ◽  
Magnetic Shear ◽  
Long Wavelength ◽  
Ideal Mhd ◽  
Gradient Change ◽  
Accelerated Particles

A possible relationship between the hot prominence transition sheath, increased internal turbulent and/or helical motion prior to prominence eruption and the prominence eruption (“disparition brusque”) is discussed. The associated darkening of the filament or brightening of the prominence is interpreted as a change in the prominence’s internal pressure gradient which, if of the correct sign, can lead to short wavelength turbulent convection within the prominence. Associated with such a pressure gradient change may be the alteration of the current density gradient within the prominence. Such a change in the current density gradient may also be due to the relative motion of the neighbouring plages thereby increasing the magnetic shear within the prominence, i.e., steepening the current density gradient. Depending on the magnitude of the current density gradient, i.e., magnetic shear, disruption of the prominence can occur by either a long wavelength ideal MHD helical (“kink”) convective instability and/or a long wavelength resistive helical (“kink”) convective instability (tearing mode). The long wavelength ideal MHD helical instability will lead to helical rotation and thus unwinding due to diamagnetic effects and plasma ejections due to convection. The long wavelength resistive helical instability will lead to both unwinding and plasma ejections, but also to accelerated plasma flow, long wavelength magnetic field filamentation, accelerated particles and long wavelength heating internal to the prominence.

Uranyl Acetate and Rotary Shadowing to Increase the Contrast of Small Aggregated Virus Particles

1969 ◽  
Vol 27 ◽  
pp. 424-425
Author(s):  
Lee F. Ellis ◽  
Richard M. Van Frank ◽  
Walter J. Kleinschmidt
Keyword(s):  
Electron Microscopy ◽  
Tissue Culture ◽  
Density Gradient ◽  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Uranyl Acetate ◽  
Interferon Inducer ◽  
Virus Particles ◽  
Staining Methods ◽  
Rotary Shadowing

The extract from Penicillum stoliniferum, known as statolon, has been purified by density gradient centrifugation. These centrifuge fractions contained virus particles that are an interferon inducer in mice or in tissue culture. Highly purified preparations of these particles are difficult to enumerate by electron microscopy because of aggregation. Therefore a study of staining methods was undertaken.

The Combining Ability of Glycoproteins IIb, IIIa and Ca2+ in EDTA-Treated Nonaggregable Platelets

1983 ◽  
Vol 50 (04) ◽  
pp. 848-851 ◽  
Author(s):  
Marjorie B Zucker ◽  
David Varon ◽  
Nicholas C Masiello ◽  
Simon Karpatkin
Keyword(s):  
Density Gradient ◽  
Combining Ability ◽  
Density Gradient Centrifugation ◽  
Gradient Centrifugation ◽  
Electrophoretic Pattern ◽  
Sucrose Density Gradient ◽  
Irreversible Loss ◽  
Sucrose Density Gradient Centrifugation ◽  
Crossed Immunoelectrophoresis ◽  
Triton X

SummaryPlatelets deprived of calcium and incubated at 37° C for 10 min lose their ability to bind fibrinogen or aggregate with ADP when adequate concentrations of calcium are restored. Since the calcium complex of glycoproteins (GP) IIb and IIIa is the presumed receptor for fibrinogen, it seemed appropriate to examine the behavior of these glycoproteins in incubated non-aggregable platelets. No differences were noted in the electrophoretic pattern of nonaggregable EDTA-treated and aggregable control CaEDTA-treated platelets when SDS gels of Triton X- 114 fractions were stained with silver. GP IIb and IIIa were extracted from either nonaggregable EDTA-treated platelets or aggregable control platelets with calcium-Tris-Triton buffer and subjected to sucrose density gradient centrifugation or crossed immunoelectrophoresis. With both types of platelets, these glycoproteins formed a complex in the presence of calcium. If the glycoproteins were extracted with EDTA-Tris-Triton buffer, or if Triton-solubilized platelet membranes were incubated with EGTA at 37° C for 30 min, GP IIb and IIIa were unable to form a complex in the presence of calcium. We conclude that inability of extracted GP IIb and IIIa to combine in the presence of calcium is not responsible for the irreversible loss of aggregability that occurs when whole platelets are incubated with EDTA at 37° C.

Gyro-Kinetic Particle Simulation of m=1 Internal Kink Mode in the Presence of Density Gradient.

1999 ◽  
Vol 75 (10) ◽  
pp. 1188-1194 ◽  
Author(s):  
Taro MATSUMOTO ◽  
Shinji TOKUDA ◽  
Yasuaki KISHIMOTO ◽  
Tomonori TAKIZUKA ◽  
Hiroshi NAITOU
Keyword(s):  
Density Gradient ◽  
Particle Simulation ◽  
Kink Mode

Study of Ablative Thermal Protection System with Density Gradient

2021 ◽  
Vol 19 (1) ◽  
pp. 116-122
Author(s):  
Toshiyuki SUZUKI ◽  
Yuki KUBOTA ◽  
Yuichi ISHIDA ◽  
Takuya AOKI ◽  
Kazuhisa FUJITA ◽  
...  
Keyword(s):  
Density Gradient ◽  
Thermal Protection ◽  
Thermal Protection System ◽  
Protection System
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