scholarly journals Brownian motion: Theory and experiment a simple classroom measurement of the diffusion coefficient

Resonance ◽  
2003 ◽  
Vol 8 (3) ◽  
pp. 71-80
Author(s):  
Kasturi Basu ◽  
Kopinjol Baishya
Keyword(s):  
Diffusion Coefficient ◽  
Brownian Motion ◽  
Theory And Experiment

scholarly journals Interactions of Human Fibrinogen in Solution

1977 ◽  
Author(s):  
E. Serrallach ◽  
W. Känzig ◽  
V. Hofmann ◽  
P.W. Straub ◽  
M. Zulauf
Keyword(s):  
Diffusion Coefficient ◽  
Brownian Motion ◽  
Rotational Diffusion ◽  
Sedimentation Coefficient ◽  
Translational Diffusion ◽  
Initial Slope ◽  
Single Pair ◽  
Human Fibrinogen ◽  
Diffusion Constants ◽  
End To End

The intriguing diversity of published translational diffusion constants for the fibrinogen molecule can hardly be explained, unless interactions between the molecules are postulated. In the present study we have investigated the possible effect of molecular association and electrostatic intermolecular interactions on the Brownian motion. The translational diffusion coefficient DT, the rotational diffusion coefficient around the minor axis DR and the sedimentation coefficient have been measured. The methods used were dynamic light scattering and analytical ultracentrifugation. The samples were solutions of purified human fibrinogen. The correlation-function corresponding to DT deviates from a single exponential. The initial slope is found to depend on concentration, being DT = (1.7 ± 0.3) 10-7 cm2/s at 10mg/ml, pH 7.4 and 0.15 molar Tris-NaCl, and increases at fibrinogen concentrations below 2mg/ml. These results are compatible with a polydispers solution, in which single molecules are in equilibrium with pair and higher aggregates. The nature of the aggregates is end-to-end as indicated from the difference between the two rotational diffusion constants DR = 40000 ± 20% and DR = 10000 ±30% s-1. On the basis of the Hall-Slayter model and assumption of end-to-end association we calculated the ratio of the sedimentation coefficient of single, pair and triplet associates, being 1:1.14:1.20. Therefore, it is difficult to separate them in a sedimentation run. For ionic strength below 0.05 molar and low fibrinogen concentration (0.lmg/ml) a fast decay appears in the correlation, indicating that the Brownian motion is strongly influenced by electrostatic interactions.

scholarly journals The Steady-State Transport of Oxygen through Hemoglobin Solutions

1966 ◽  
Vol 49 (4) ◽  
pp. 663-679 ◽  
Author(s):  
K. H. Keller ◽  
S. K. Friedlander
Keyword(s):  
Diffusion Coefficient ◽  
Brownian Motion ◽  
Steady State ◽  
Effective Diffusion ◽  
Close Correlation ◽  
Oxygen Electrode ◽  
Low Oxygen ◽  
Diffusion Rates ◽  
Oxygen Tensions ◽  
Diffusion Coefficient Of Oxygen

The steady-state transport of oxygen through hemoglobin solutions was studied to identify the mechanism of the diffusion augmentation observed at low oxygen tensions. A novel technique employing a platinum-silver oxygen electrode was developed to measure the effective diffusion coefficient of oxygen in steady-state transport. The measurements were made over a wider range of hemoglobin and oxygen concentrations than previously reported. Values of the Brownian motion diffusion coefficient of oxygen in hemoglobin solution were obtained as well as measurements of facilitated transport at low oxygen tensions. Transport rates up to ten times greater than ordinary diffusion rates were found. Predictions of oxygen flux were made assuming that the oxyhemoglobin transport coefficient was equal to the Brownian motion diffusivity which was measured in a separate set of experiments. The close correlation between prediction and experiment indicates that the diffusion of oxyhemoglobin is the mechanism by which steady-state oxygen transport is facilitated.

The convergence of a branching Brownian motion used as a model describing the spread of an epidemic

1980 ◽  
Vol 17 (2) ◽  
pp. 301-312 ◽  
Author(s):  
Frank J. S. Wang
Keyword(s):  
Diffusion Coefficient ◽  
Brownian Motion ◽  
Unit Area ◽  
Transition Probability ◽  
Random Variable ◽  
Two Dimensional ◽  
Infection Period ◽  
Branching Brownian Motion ◽  
Almost Everywhere ◽  
Probability Rate

A spatial epidemic process where the individuals are located at positions in the Euclidean space R2 is considered. The infective individuals, with an infection period that is exponentially distributed with parameter µ, move in R2 according to a Brownian motion with a diffusion coefficient σ2. The susceptible individuals may also move. But we shall use the approximation that they remain unchanged in numbers and therefore assume that the averaged ‘density' of susceptibles per unit area is the same throughout space and time. The transition probability rate of infection of a susceptible in the infinitesimal element of area dy by an infective in dx is assumed to be a function h(x – y |) of the distance | x – y | between x and y. Then our process can be considered as a two-dimensional birth and death Brownian motion. Let be the number of infective individuals in the set D at time t and . The almost everywhere convergence of the random variables to a limit random variable W(D) is established.

The convergence of a branching Brownian motion used as a model describing the spread of an epidemic

1980 ◽  
Vol 17 (02) ◽  
pp. 301-312 ◽  
Author(s):  
Frank J. S. Wang
Keyword(s):  
Diffusion Coefficient ◽  
Brownian Motion ◽  
Unit Area ◽  
Transition Probability ◽  
Random Variable ◽  
Two Dimensional ◽  
Infection Period ◽  
Branching Brownian Motion ◽  
Almost Everywhere ◽  
Probability Rate

A spatial epidemic process where the individuals are located at positions in the Euclidean space R 2 is considered. The infective individuals, with an infection period that is exponentially distributed with parameter µ, move in R 2 according to a Brownian motion with a diffusion coefficient σ 2. The susceptible individuals may also move. But we shall use the approximation that they remain unchanged in numbers and therefore assume that the averaged ‘density' of susceptibles per unit area is the same throughout space and time. The transition probability rate of infection of a susceptible in the infinitesimal element of area dy by an infective in dx is assumed to be a function h(x – y |) of the distance | x – y | between x and y. Then our process can be considered as a two-dimensional birth and death Brownian motion. Let be the number of infective individuals in the set D at time t and . The almost everywhere convergence of the random variables to a limit random variable W(D) is established.

scholarly journals Preemption Games: Theory and Experiment

2010 ◽  
Vol 100 (4) ◽  
pp. 1778-1803 ◽  
Author(s):  
Steven T Anderson ◽  
Daniel Friedman ◽  
Ryan Oprea
Keyword(s):  
Brownian Motion ◽  
Nash Equilibrium ◽  
Laboratory Experiment ◽  
Geometric Brownian Motion ◽  
The Other ◽  
Investment Opportunity ◽  
Bayesian Nash Equilibrium ◽  
Games Theory ◽  
Investment Patterns ◽  
Theory And Experiment

Several impatient investors with private costs Ci face an indivisible irreversible investment opportunity whose value V is governed by geometric Brownian motion. The first investor i to seize the opportunity receives the entire payoff, V-Ci. We characterize the symmetric Bayesian Nash equilibrium for this game. A laboratory experiment confirms the model's main qualitative predictions: competition drastically lowers the value at which investment occurs; usually the lowest-cost investor preempts the other investors; observed investment patterns in competition (unlike monopoly) are quite insensitive to changes in the Brownian parameters. Support is more qualified for the prediction that markups decline with cost. (JEL C73, D44, D82, G31)

‘Slow-down’ of diffusion coefficient in finite Brownian motion

1991 ◽  
Vol 74 (4) ◽  
pp. 785-793 ◽  
Author(s):  
M.A. López-Quintela ◽  
C. Tojo ◽  
M.C. Buján-Núñez
Keyword(s):  
Diffusion Coefficient ◽  
Brownian Motion
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