Absorption by static traps: Initial‐value and steady‐state problems

1984 ◽  
Vol 81 (8) ◽  
pp. 3666-3677 ◽  
Author(s):  
Marshall Fixman
Keyword(s):  
Steady State ◽  
Initial Value

scholarly journals Ionized calcium concentrations in squid axons.

1976 ◽  
Vol 67 (4) ◽  
pp. 433-467 ◽  
Author(s):  
R Dipolo ◽  
J Requena ◽  
F J Brinley ◽  
L J Mullins ◽  
A Scarpa ◽  
...  
Keyword(s):  
Steady State ◽  
Light Emission ◽  
Mean Value ◽  
Ionized Calcium ◽  
Initial Value ◽  
Light Levels ◽  
Light Measurement ◽  
Ca 50 ◽  
Subsequent Introduction

Values for ionized [Ca] in squid axons were obtained by measuring the light emission from a 0.1-mul drop of aequorin confined to a plastic dialysis tube of 140-mum diameter located axially. Ionized Ca had a mean value of 20 x 10(-9) M as judged by the subsequent introduction of CaEGTA/EGTA buffer (ratio ca. 0.1) into the axoplasm, and light measurement on a second aequorin drop. Ionized Ca in axoplasma was also measured by introducing arsenazo dye into an axon by injection and measuring the Ca complex of such a dye by multichannel spectrophotometry. Values so obtained were ca. 50 x 10(-9) M as calibrated against CaEGTA/EGTA buffer mixtures. Wth a freshly isolated axon in 10 mM Ca seawater, the aequorin glow invariably increased with time; a seawater [Ca] of 2-3 mM allowed a steady state with respect to [Ca]. Replacement of Na+ in seawater with choline led to a large increase in light emission from aequorin. Li seawater partially reversed this change and the reintroduction of Na+ brought light levels back to their initial value. Stimulation at 60/s for 2-5 min produced an increase in aequorin glow about 0.1% of that represented by the known Ca influx, suggesting operationally the presence of substantial Ca buffering. Treatment of an axon with CN produced a very large increase in aequorin glow and in Ca arsenazo formation only if the external seawater contained Ca.

scholarly journals The response to a hot spot in a combustion problem

1981 ◽  
Vol 23 (1) ◽  
pp. 95-102 ◽  
Author(s):  
K. K. Tam ◽  
M. T. Kiang
Keyword(s):  
Steady State ◽  
Simple Model ◽  
Initial Value Problem ◽  
Initial Temperature ◽  
Hot Spot ◽  
Steady State Solution ◽  
Initial Value ◽  
Multiple Steady State ◽  
Steady State Solutions ◽  
Combustion Problem

AbstractA simple model for a problem in combustion theory has multiple steady state solutions when a parameter is in a certain range. This note deals with the initial value problem when the initial temperature takes the form of a hot spot. Estimates on the extent and temperature of the spot for the steady state solution to be super-critical are obtained.

Two Phases of Ageing in Drosophila Subobscura

1961 ◽  
Vol 38 (3) ◽  
pp. 679-684
Author(s):  
JEAN M. CLARKE ◽  
J. MAYNARD SMITH
Keyword(s):  
Steady State ◽  
Life Span ◽  
Low Temperatures ◽  
Initial Value ◽  
Male And Female ◽  
Higher Temperature ◽  
Two Phases ◽  
Lower Temperature ◽  
The Individual

1. Male and female D. subobscura were kept for varying periods at low temperatures 3-20° C.) and then transferred to a higher temperature (26-30° C.) and kept there until they died. 2. It was found that during the early part of the life span, over the range 15-30° C., every day spent at a low temperature reduced the expectation of life at a higher temperature by approximately 1 day. Later, when the expectation of life at the higher temperature had fallen to about half its initial value, little further change in this expectation occurred with increasing age at a lower temperature. 3. It is concluded that the life span can be divided into two phases, (i) an irreversible ‘ageing’ process whose rate is approximately independent of temperature from 15 to 30° C., but which is slower at 3° C., and (ii) a ‘dying’ process which is initiated when ageing has proceeded to a stage at which the individual is no longer capable of maintaining a steady state at the temperature at which it is living, although the same individual would be capable of maintaining a steady state at some lower temperature. 4. The rate of the dying process is highly dependent on temperature, and it can be reversed in flies transferred to lower temperatures.

scholarly journals Age-Related Reductions in Cerebral Vasomotor Reactivity and the Law of Initial Value: A 4-Year Prospective Longitudinal Study

1985 ◽  
Vol 5 (1) ◽  
pp. 79-85 ◽  
Author(s):  
Robert L. Rogers ◽  
John S. Meyer ◽  
Karl F. Mortel ◽  
Roderick K. Mahurin ◽  
John Thornby
Keyword(s):  
Steady State ◽  
Longitudinal Study ◽  
Gray Matter ◽  
Pure Oxygen ◽  
Initial Value ◽  
Prospective Longitudinal Study ◽  
Vasomotor Reactivity ◽  
Cerebral Vasomotor Reactivity ◽  
The Law ◽  
Prospective Longitudinal

A group of 51 neurologically normal, middle-aged and elderly volunteers (aged 35–86 years; mean age 63.24 years) with and without risk factors for stroke were given annual tests of cerebral vasomotor reactivity to assess any changes in the cerebral vascular capacitance associated with advancing age that might alter cerebral vasomotor reactivity. Cerebral vasomotor reactivity was estimated as the difference in bihemisphere gray matter CBF measured by the 133Xe inhalation method in the steady state breathing room air, followed by a second measurement during inhalation of 100% oxygen. There were significant and progressive reductions in cerebral vasomotor reactivity during the 4-year longitudinal study. Positive linear correlations were apparent between initial steady-state mean bihemisphere gray matter CBF levels and degrees of vasomotor reactivity, suggesting that the Law of Initial Value plays an important role. This should be borne in mind when analyzing scores of cerebral vasomotor reactivity. In the present communication, analysis of covariance was used to correct for influences of initial CBF levels on vasomotor responses tested while breathing pure oxygen.

A New Solution of a Nonlinear Model of Upwelling

2005 ◽  
Vol 35 (4) ◽  
pp. 532-544 ◽  
Author(s):  
P. F. Choboter ◽  
R. M. Samelson ◽  
J. S. Allen
Keyword(s):  
Steady State ◽  
Pressure Gradient ◽  
Nonlinear Model ◽  
Initial Value Problem ◽  
Coastal Upwelling ◽  
Steady State Solution ◽  
Surface Flow ◽  
State Solution ◽  
Initial Value ◽  
Surface Jet

Abstract A two-dimensional, frictionless, nonlinear model of coastal upwelling is reexamined. The model has been solved previously at steady state and as an initial-value problem. The previous solution to the initial-value problem is inconsistent with the steady-state solution. A new solution to the spinup problem is presented that approaches the existing steady-state solution. In the new solution, a surface equatorward jet develops more rapidly than a poleward undercurrent, but the surface jet is of limited strength so that the undercurrent velocity eventually surpasses that of the surface flow. Consideration of dimensional scales implies that the magnitude of the wind stress determines how quickly steady state is approached but does not affect the steady-state fields. Exact solutions found with an arbitrary alongshore pressure gradient imply that there is no poleward flow without a poleward pressure gradient.

Forsterite dissolution in superheated basaltic, andesitic and rhyolitic melts

1990 ◽  
Vol 54 (374) ◽  
pp. 67-74 ◽  
Author(s):  
C. H. Donaldson
Keyword(s):  
Steady State ◽  
Natural Convection ◽  
Dissolution Rate ◽  
Atmospheric Pressure ◽  
Initial Value ◽  
Steady State Condition ◽  
Rate Of Dissolution ◽  
Constant Rate ◽  
The Difference ◽  
Initial Dissolution Rate

AbstractDissolution rates of small forsterite spheres in superheated melts of basalt, andesite and rhyolite composition have been measured at 1300°C, atmospheric pressure. The rate is constant (83 µm hr−1) in the basalt, regardless of run duration. In the andesite the initial dissolution rate is 200µm hr−1, followed by a decrease to a constant value of 16µmhr−1 in 2–3 hours. Dissolution rate in the rhyolite decreases from an initial value of 1.7 to <0.1 µmhr−1 over 280 hours and never reaches a constant rate. Once the rate of dissolution has become constant, the film of contaminated melt that forms in melt about a crystal does not thicken with time, indicating attainment of a steady-state condition. Steady state is attributed to natural convection arising from the difference in density between the film of contaminated melt surrounding a crystal and that beyond. The density difference is approximately 2% of the density of the rock melt.

Oblique collisions of internal wave beams and associated resonances

2012 ◽  
Vol 711 ◽  
pp. 337-363 ◽  
Author(s):  
T. R. Akylas ◽  
H. H. Karimi
Keyword(s):  
Steady State ◽  
Internal Gravity Wave ◽  
Nonlinear Interactions ◽  
Resonant Response ◽  
Initial Value ◽  
Oblique Collision ◽  
The Difference ◽  
Forced Waves ◽  
Radiation Conditions ◽  
Steady State Amplitude

AbstractQuadratic nonlinear interactions between two colliding internal gravity wave beams in a uniformly stratified fluid, and the resulting radiation of secondary beams with frequencies equal to the sum and difference of those of the primary beams, are discussed. The analysis centres on oblique collisions, involving beams that propagate in different vertical planes. The propagation directions of generated secondary beams are deduced from kinematic considerations and the use of radiation conditions, thus extending to oblique collisions previously derived selection rules for plane collisions. Using small-amplitude expansions, radiated-beam profiles at steady state are also computed in terms of the characteristics of the colliding beams. It is pointed out that, for certain oblique collision configurations, radiated beams with frequency equal to the difference of the primary frequencies have unbounded steady-state amplitude. This resonance, which has no counterpart for plane collisions, is further analysed via the solution of an initial-value problem; ignoring dissipation, the transient resonant response grows in time like ${t}^{1/ 2} $, a behaviour akin to that of forced waves at cut-off frequencies.

Waves on a shear flow

1974 ◽  
Vol 11 (2) ◽  
pp. 263-277 ◽  
Author(s):  
K.K. Puri
Keyword(s):  
Free Surface ◽  
Steady State ◽  
Shear Flow ◽  
Initial Value Problem ◽  
Finite Depth ◽  
Steady State Solution ◽  
State Solution ◽  
Wave System ◽  
Initial Value ◽  
Oscillatory Pressure

The propogation of disturbance when a shear flow with a free surface, in a channel of infinite horizontal extent and finite depth, is disturbed by the application of time-oscillatory pressure, is studied. The initial value problem is solved by using transform techniques and the steady state solution is obtained therefrom in the limit t → ∞. The effect of the initial shear on the development of the wave system is investigated.

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