Survival fitness

The expanding field of avian immunoecology has provided strong evidence that suppressed immunity leads to ecologically relevant consequences in wild birds. In a review of 12 immune function studies, immune responses were the most significant predictors of subsequent survival of young wild birds [107], In an assessment of 280 introduction attempts in 38 avian species, immunocompetence as assessed by the PHA skin response was an important positive predictor of the ability of birds to colonize new areas (i.e., found new local populations) [108], Similar assessments of survival, fitness, and dispersal ability should be conducted within the context of immunotoxicological studies of wild birds. 

The factor / is a reproductive fitness measure that compounds the relative ability of resist nts, compared to susceptibles, in germination, establishment, growth, seed production and survival. Fitness is thus always measured when the resistant and susceptible individuals are in competition with each other in the absence of selection for the mutants. When they are grown separately the resistant individuals are often less productive , and in competitive situations the resistant individuals are more affected (Table I). (See Appendix 1 for exact mathematical definitions.)... 

Coren S, Halpern DF (1991) Left-handedness - a marker for decreased survival fitness. Psychological Bulletin 109 90-106. 

Insofar as complex adaptive systems can be regarded as being essentially open-ended problem-solvers, their lifeblood consists mostly of novelty. The ability of a complex adaptive system to survive and evolve in a constantly changing environment is determiimd by its ability to continually find — either by chance, or experience, or more typically both insightful new strategies to increase its overall fitness (which is, of course, a constantly changing function in time). 

A common use is with a plastic hub or boss accepting either a plastic or metal insert. The press fit operation tends to expand the hub creating a tensile or hoop stress. If the interference is too great, a very high strain and stress will develop. The plastic product will (1) fail immediately by developing a crack parallel to the axis of the hub to relieve the stress, a typical hoop stress failure, (2) survive assembly but fail prematurely when the product is in use for a variety of... 

The versatility of the plastic materials permits them to be varied to perform special functions. By applying ingenuity to these amazingly adaptable materials, we can produce products that add to the worldwide survival capability of life under severe environments and improve the quality of life under normal environments. The designer s role in fitting the possibilities to the needs is one that is increasingly important. 

The processes of evolution have been remarkably successful in creating animals that are well adapted to their environment. By continually adjusting the population through genetic mutation, evolutionary change works toward the perfect individual to fill a particular environmental niche. Not every new individual is well suited to its environment, of course, and the fitness of new individuals is repeatedly tested as the animals try to survive, prosper, and reproduce. 

A functional explanation for a particular trait does not stipulate by which mechanism within the organism a particular effect is produced. The function can be realized in physically different ways and the only relevant feature is that it must enhance fitness, i.e. serve survival and reproduction (Macdonald, 1992). Various causal factors can then be invoked to explain how the function is performed, although these factors cannot explain why the traits are present unless an appeal is made to selection pressure. 

A number of attempts have been made to select on nematode immune-related traits. Lines of Heligmosomoides polygyrus have been selected in hosts with different histories of previous exposure (naive, once previously exposed, or multiply previously exposed). This resulted in parasite lines that differed in fitness when tested in semi-immune animals, with the lines selected in the hosts with greatest previous exposure surviving best and... 

The results of stress-strain measurements can be summarized as follows (1) the reduced stress S (A- A ) (Ais the extension ratio) is practically independent of strain so that the Mooney-Rivlin constant C2 is practically zero for dry as well as swollen samples (C2/C1=0 0.05) (2) the values of G are practically the same whether obtained on dry or swollen samples (3) assuming that Gee=0, the data are compatible with the chemical contribution and A 1 (4) the difference between the phantom network dependence with the value of A given by Eq.(4) and the experimental moduli fits well the theoretical dependence of G e in Eq.(2) or (3). The proportionality constant in G for series of networks with s equal to 0, 0.2, 0.33, and 0. Ewas practically the same -(8.2, 6.3, 8.8, and 8.5)x10-4 mol/cm with the average value 7.95x10 mol/cm. Results (1) and (2) suggest that phantom network behavior has been reached, but the result(3) is contrary to that. Either the constraints do survive also in the swollen and stressed states, or we have to consider an extra contribution due to the incrossability of "phantom" chains. The latter explanation is somewhat supported by the constancy of in Eq.(2) for a series of samples of different composition. 

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