THE DECOUPLING & SOLUTION OF LOGISTIC & CLASSICAL TWO-SPECIES LOTKA-VOLTERRA DYNAMICS WITH VARIABLE PRODUCTION RATES

BIOMAT 2007 ◽  
2008 ◽  
Author(s):  
CHARLES E. M. PEARCE ◽  
ROY B. LEIPNIK
Keyword(s):  
Production Rates ◽  
Variable Production

THE DECOUPLING AND SOLUTION OF LOGISTIC AND CLASSICAL TWO-SPECIES LOTKA-VOLTERRA DYNAMICS WITH VARIABLE PRODUCTION RATES

2008 ◽  
Vol 03 (01n02) ◽  
pp. 183-194
Author(s):  
CHARLES E. M. PEARCE ◽  
ROY B. LEIPNIK
Keyword(s):  
Population Biology ◽  
Mass Action ◽  
Volterra Equations ◽  
Qualitative Information ◽  
Production Rates ◽  
Biological Features ◽  
Dynamics Of Population ◽  
Population Sizes ◽  
Evolution With Time ◽  
Variable Production

Central to the dynamics of population biology are various versions of the Lotka-Volterra equations. Particular cases may be used to model competitive, commensal, predatory and other behaviour. Similar equations describe macro-economic interactions, epidemics and other processes of mass action. Refinements of many versions of these equations have been exhibited in the BIOMAT meetings to describe new biological features. The solutions to such equations may display a variety of forms. Broadly speaking, quite a lot of qualitative information may often be obtained about the solutions. In many cases it is convenient to eliminate time from the equations, so obtaining equations for the joint values of population sizes. By contrast, determining explicit expressions for the evolution with time of the component population sizes frequently appears to be infeasible, although numerical procedures may be available.

VARIATION OF CORTISOL METABOLISM AS A CONTRIBUTING FACTOR TO DISCREPANCIES IN THE MEASUREMENT OF CORTISOL PRODUCTION RATE

1972 ◽  
Vol 70 (1) ◽  
pp. 89-96 ◽  
Author(s):  
M. J. Levell
Keyword(s):  
Production Rate ◽  
Isotope Dilution ◽  
Normal Subjects ◽  
Contributory Factor ◽  
Morning Dose ◽  
Production Rates ◽  
Evening Dose ◽  
Cortisol Metabolism

ABSTRACT Five normal subjects were given [14C] cortisol in the morning and [3H] cortisol in the evening, in both cases by mouth. The excretion of radioactivity in tetrahydrocortisol (THF) and tetrahydrocortisone (THE) was measured by a modified form of reverse isotope dilution. In 2 subjects, the ratio of isotopic THF/isotopic THE was higher after the evening dose than after the morning dose. In 1 subject the ratio decreased. In 2 subjects it did not change. Cortisol production rates calculated from THF were usually higher than those calculated from THE. The observed variations of metabolism were only a contributory factor to these discrepancies.

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