scholarly journals Classical diffusion: theory and simulation codes

1978 ◽  
Author(s):  
H Grad ◽  
P N Hu
Keyword(s):  
Diffusion Theory ◽  
Classical Diffusion ◽  
Simulation Codes

scholarly journals Successive waves in pandemic infections: physical diffusion theory and data comparisons

2020 ◽  
Author(s):  
Romney B Duffey
Keyword(s):  
Health Policy ◽  
Physical Model ◽  
Diffusion Theory ◽  
Medical System ◽  
Policy Implications ◽  
Classical Diffusion ◽  
Simple Physical Model ◽  
Diffusive Effects ◽  
Physical Principles

AbstractWe establish the principal that the prediction, timing and magnitude of second and more distinct waves of infection can be based on the well - known physics and assumptions of classical diffusion theory. This model is fundamentally different from the commonly used SEIR and R0 fitting methods. Driven by data, we seek a working approximation for the observed orders of magnitude for the timing and rate of second and more waves. The dynamic results and characteristics are compared to the data and enable predictions of timescales and maximum expected rates where diffusive effects dominate.The important point is this simple physical model allows understanding of the dominant processes, provides prediction estimates, and is based the solutions derived from existing, consistent and well-known physical principles. The medical system and health policy implications of such inexorable diffusive spread are that any NPI and other countermeasures deployed for and after the rapid first peak must recognize that large residual infection waves will then likely occur.

QELSS diffusion data for moderately broad molar mass distribution polymer samples compared with data from classical gradient techniques

1989 ◽  
Vol 54 (7) ◽  
pp. 1821-1829
Author(s):  
Bedřich Porsch ◽  
Simon King ◽  
Lars-Olof Sundelöf
Keyword(s):  
Diffusion Coefficient ◽  
Mass Distribution ◽  
Molar Mass ◽  
Molar Mass Distribution ◽  
Diffusion Data ◽  
Mass Distributions ◽  
Classical Diffusion ◽  
Polydisperse Polymer

The differences between the QELSS and classical diffusion coefficient of a polydisperse polymer resulting from distinct definitions of experimentally accessible average values are calculated for two assumed specific forms of molar mass distributions. Predicted deviations are compared with the experiment using NBS 706 standard polystyrene. QELSS Dz of this sample relates within 2-4% to the classical diffusion coefficient, if the Schulz-Zimm molar mass distribution is assumed to be valid. In general, differences between the height-area and QELSS diffusion coefficient of about 20% may be found for Mw/Mn ~ 2, and this value may increase above 35%, if strongly tailing molar mass distribution pertains to the sample.

The Adoption of Health Promotion Programs by State Agencies

1987 ◽  
Vol 16 (3) ◽  
pp. 235-242 ◽  
Author(s):  
Nell H. Gottlieb ◽  
Linda E. Lloyd ◽  
Jean N. Bounds
Keyword(s):  
Health Promotion ◽  
Diffusion Theory ◽  
General Interest ◽  
State Agencies ◽  
Health Promotion Programs ◽  
Potential Benefits ◽  
Education Act ◽  
One Year ◽  
Time And Energy ◽  
Personnel Directors

Personnel directors of Texas state agencies were surveyed one month prior to and one year following the passage of the 1983 Texas State Employee Health Fitness and Education Act. This legislation allowed the agencies to use available funds and facilities for health promotion programs. Most of the personnel directors were aware of the Act and of the potential benefits of health promotion programs. There was general interest in learning more about health promotion, available community resources, and about the time and energy commitments in developing a program. Most believed they would implement programs in the future. In the year following the passage of the Act, 16 percent of the agencies, covering 30,852 employees, had received approval to begin programs. Size was positively related to plan development and approval. The results are discussed using diffusion theory.

Neutron noise calculation: A comparative study between SP3 theory and diffusion theory

2021 ◽  
Vol 156 ◽  
pp. 108184
Author(s):  
Helin Gong ◽  
Zhang Chen ◽  
Wenbin Wu ◽  
Xingjie Peng ◽  
Qing Li
Keyword(s):  
Comparative Study ◽  
Diffusion Theory ◽  
Neutron Noise ◽  
And Diffusion
Sign in / Sign up

Export Citation Format

Share Document