Survival-of-the-fittest

The evolution of superalloys has been splendidly mapped by an Ameriean metallurgist, Sims (1966, 1984), while the more restrieted tale of the British side of this development has been told by Pfeil (1963). I have analysed (Cahn 1973) some of the lessons to be drawn from the early stages of this story in the eontext of the methods of alloy design it really is an evolutionary tale... the survival of the fittest, over and over again. The present status of superalloy metallurgy is eoneisely presented by MeLean (1996). 

Neff T, Beard BC, Kiem HP (2006) Survival of the fittest in vivo selection and stem ceU gene therapy. Blood 107 1751-1760... 

Mulkidjanian, A.Y., Cherepanov, D.A. and Galperin, M.Y. (2003). Survival of the fittest before the beginning of life selection of oligonucleotide-like polymers by UV-light. BMC Evolutionary Biology, 3, 1-7 and references therein... 

Fishlock, D. (1990, April 24). Survival of the fittest drugs. Financial Times, pp. 16-17. 

At the heart of the GA are evolutionary operators These are a survival of the fittest operator, and a pair of modification operators whose role is to create new strings. To apply the first of these operators, the fitter members of the starting population are selected preferentially as parents for the next generation. This, of course, requires that we know what is meant by, and can calculate, the fitness of each string. 

The next step is to apply survival of the fittest within the population to determine which of the current strings will act as parents for the next generation. In the GA, as in nature, a stochastic, random, element enters into this process, so the process is more survival of the fittest (usually). Fitter strings... 

With such a disparity between the best (ROS > 15%) and worst (ROS < 5%, sometimes negative) performers, a survival of the fittest condition is developing (see Chapter 20)... 

Evolutionary algorithms are frequently used to find optimal solutions in many different problem areas. They are based on Darwin s principle of survival of the fittest (Darwin 1996 Maynard Smith 1993). A population of individuals has to compete with other individuals for access to food and mates. Only the successful ones are allowed to reproduce. This leads to the reproduction of certain inheritable traits into the next generation. 

Selecting the points for crossover and mutation according to a probability distribution, either uniform or skewed towards points at which the optimized function takes high values (the latter being a probabilistic expression of the survival-of-the-fittest principle). 

Evolutionary computation approaches are optimization methods. They are conveniently presented using the metaphor of natural evolution a randomly initialized population of individuals evolves following a crude parody of the Darwinian principle of the survival of the fittest. New individuals are generated using simulated evolutionary operations such as mutations. The probability of survival of the newly generated solutions depends on their fitness (how well they perform with respect to the optimization problem at hand) the best are kept with a high probability, the worst are rapidly discarded. 

N. Bardsley, Display search, Survival of the fittest, talk given at USDC investor s conference, New York, March 15th 2005. 

By analogy, analytical systems, to remain viable, must be able to fill some useful role. Thus, the question of which system is the best is academic. By analogy with the evolutionary concept of the survival of the fittest, only those analytical systems which can actually solve "real" analytical problems will survive. Because there are alternative analytical techniques with multielement capability, viable spectroscopic methods must be able to offer real advantages or increased capabilities to compete with these techniques in at least certain analytically-important situations. 

It is now time to start the evolutionary clock running. To create a new generation of individuals, selections are made from among the members of the present population, copying chosen members one by one into a new population. Survival of the fittest dictates that, in selecting individuals to form part of the next generation, we should choose preferentially the better solutions. Members from the first population which are picked to be placed into the next one are parents their progeny are referred to as children. 

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