Ludwig von Bertalanffy:
photocredit: ucl.ac.uk
Growth:
"If 'growth' is understood to be the growth rates of pups or juveniles (large sharks no longer grow much) then we can replace L by Lo and now compare two shark of SIMILAR Loo. Furthermore let's assume that Loo>>Lo, and we have k ~ (dL/dt)/Loo i.e. k is proportional to dL/dt.
k in the VBGF is assumed to be a constant. However, Von Bertalanffy (1960) indicated that k could change as a shark get older. Sevengill shark growth data indicated that indeed k is not constant and becomes smaller as they get older.
The VBGF is a 3 parameter equation. In principle, three data points determine the parameters...
The von Bertalanffy growth function (VBGF) introduced by von Bertalanffy in 1938 predicts the length of a shark as a function of its age, L = L(t): L(t) = Loo - (Loo - Lo) exp(-kt)"
http://homepage.mac.com/mollet/VBGF/VBGF.html
photocredit: qmssjp
"In its simplest version the so-called von Bertalanffy growth equation is expressed as a differential equation of length (L) over time (t): 
when k is the individual growth rate and 
the maximum individual length."
Bertalanffy, L. von (1938). "A quantitative theory of organic growth (Inquiries on growth laws. II)". Human Biol. 10: 181-213.
http://en.wikipedia.org/wiki/Ludwig_von_Bertalanffy
The concept of system, though it seems to be intrinsic to human thinking, has been extensively employed and developed over the last few decades, due in a large measure to contributions made by Karl Ludwig von Bertalanffy (1901-1972), a Viennese professor of biology. He worked to identify structural, behavioral and developmental features common to particular classes of living organisms. One approach was to look over the empirical universe and pick out certain general phenomena which are found in many different disciplines, and to seek to build up general theoretical s relevant to these phenomena, e.g., growth, homeostasis, evolution. Another approach was to arrange the empirical fields in a hierarchy of complexity of organization of their basic 'individuality' or units of behavior, and to try to develop a level of abstraction appropriate to each. Examples are generalizations on the levels of cells, simple organs, open self-maintaining organisms, small groups of organisms, society and the universe."
Gregory Mitchell
http://www.trans4mind.com/mind-development/systems.html
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