18 found
Sort by:
Disambiguations:
I. Walker [13]Ian Walker [4]I. A. Walker [1]Ian R. Walker [1]
Iain Walker [1]Ilse Walker [1]
  1. Gail Moloney & Iain Walker (2000). Messiahs, Pariahs, and Donors: The Development of Social Representations of Organ Transplants. Journal for the Theory of Social Behaviour 30 (2):203–227.
    This longitudinal, qualitative study investigated the genesis and transformation of the social representations of organ transplants. A search of the West Australian newspaper, from 1954 to 1995 found 672 articles pertaining to organ transplants. Two distinct, but conflicting, representations emerged in the analyses. In the first representation, found from 1967/68, the surgeon was paramount and organ transplants were iconised as ‘spare part surgery’. In the second representation, found from 1984/85, the role of the donor was emphasised and transplants iconised as (...)
    No categories
    Direct download (6 more)  
     
    My bibliography  
     
    Export citation  
  2. Ian Walker (1997). Peter J. HampsonPeter E. MorrisUnderstanding Cognition1996Blackwell0 631 15749 2; 0 631 15751 4399£ 50.00. Trends in Cognitive Sciences 1 (2):83.
     
    My bibliography  
     
    Export citation  
  3. I. Walker (1996). Prediction of Evolution? Somatic Plasticity as a Basic, Physiological Condition for the Viability of Genetic Mutations. Acta Biotheoretica 44 (2):165-168.
    The argument is put forward that genetic mutations are viable then only, when the changed pattern of growth and/or metabolism is accommodated by the taxon-specific biochemistry of the organisms, i.e. by adaptive, somatic/physiological plasticity. The range of somatic plasticity under changing environmental conditions, therefore, has a certain predictive value for the kind of mutations that are likely to be viable.
    Direct download (2 more)  
     
    My bibliography  
     
    Export citation  
  4. I. Walker (1994). Minding the Emperor's New Mind. Acta Biotheoretica 42 (1):77-84.
    This essay equates Penrose's (1989) Emperor with the scientist engaging in mental (Schrödinger's cat) or real experiments.The simultaneous presence of apparently contradictory phase-spatial symmetry conditions on the various hierarchical levels of biological systems are seen as the result of genetic and neurophysiological information that interferes with the physico-chemical vectors between the structural components of the system, the experimenter being an integral part of this informational causality. Equations pertaining to the lowest structural levels of matter, therefore, may not be extendable over (...)
    Direct download (2 more)  
     
    My bibliography  
     
    Export citation  
  5. D. W. Bethune, S. Ghosh, B. Gray, L. Kerr, I. A. Walker, L. A. Doolan, R. J. Harwood & L. D. Sharples (1993). Learning During General Anesthesia: Implicit Recall Following Methohexital or Propofol Infusion. In P. S. Sebel, B. Bonke & E. Winograd (eds.), Memory and Awareness in Anesthesia. Prentice-Hall.
    No categories
     
    My bibliography  
     
    Export citation  
  6. I. Walker (1993). Competition and Information. Acta Biotheoretica 41 (3):249-266.
    Reconsideration of the logistic equation and of its expansion to the special and general Volterra competition equations in terms of mass/energy in phase-space, shows that information on the phase-spatial conditions of resource and consumers determines specific population parameters which, in turn, decide on coexistence and extinction.Thus, introduction ofInformation as a separate and independent biophysical parameter, in analogy, and in addition, to Force in Classical Physics, is necessary. This allows for quantification of informational effects on resource flows and population numbers. As (...)
    Direct download (2 more)  
     
    My bibliography  
     
    Export citation  
  7. I. Walker (1991). Ideas in Theoretical Biology Why Legs and Not Wheels? Acta Biotheoretica 39 (2):151-155.
    The inanimate world, including Man's wheeled vehicles, follow the classical mechanical laws: trajectories of objects in phase-space are predictable on the basis of the vectors of forces acting on the objects. Animal locomotion does not involve wheels, but relies on antagonistic contractile fibre systems, and defies prediction of trajectories. These features are tied up with the faculty of immediate steering in response to momentaneous physiological and environmental stimuli. Thus, animal motor systems have two relatively independent inputs: the sensory/information system, which (...)
    Direct download (2 more)  
     
    My bibliography  
     
    Export citation  
  8. A. Steiner & I. Walker (1990). The Pattern of Population Growth as a Function of Redundancy and Repair. Acta Biotheoretica 38 (2):83-90.
    A basic model of hierarchical structure, expressed by simple, linear differential equations, shows that the pattern of population growth is essentially determined by conditions of redundancy in the sub-structure of individuals. There does not exist any possible combination between growth rate and accident rate that could balance population numbers and/or the level of redundancy within the population; all possible combinations either lead to extinction or to positive population growth with a decline of the fraction of individuals with redundant substructure. Declining (...)
    Direct download (2 more)  
     
    My bibliography  
     
    Export citation  
  9. I. Walker (1987). Compartmentalization and Niche Differentiation: Causal Patterns of Competition and Coexistence. Acta Biotheoretica 36 (4):215-239.
    The current major models of coexistence of species on the same resources are briefly summarized. It is then shown that analysis of supposedly competitive systems in terms of the physical four dimensions of phase-space is sufficient to understand the causes for coexistence and for competitive exclusion. Thus, the multiple dimensions of niche theory are reduced to factors which define the magnitudes of the phase-spatial system, in particular the boundaries of population spaces and of periods of activity. Excluding possible cooperative interaction (...)
    Direct download (2 more)  
     
    My bibliography  
     
    Export citation  
  10. I. Walker (1984). The Volterra Competition Equations with Resource - Independent Growth Coefficients and Discussion on Their Biological and Biophysical Implications. Acta Biotheoretica 33 (4):253-270.
    Analysis of the biophysical conditions for a correct application of the Volterra Competition Equations with resource-independent coefficients reveals the following:The traditional, mathematical formalism with the two equations representing two straight lines at the condition of zero growth applies.
    Direct download (2 more)  
     
    My bibliography  
     
    Export citation  
  11. I. Walker (1983). The Physical Dimensions and Biological Meaning of the Coefficients in the Volterra Competition Equations and Their Consequences for the Possibility of Coexistence. Acta Biotheoretica 32 (2):93-122.
    Exact definitions in physical and biological terms of the coefficients in Volterra's (1926, 1931) original competition equations are indispensable for the understanding of the system. In agreement with Volterra's own, but not quite sufficient specifications, it is tried in this paper to give more precise definitions of the parameters used by Volterra. This leads to some consequences; i.a. that there does not exist a principle of competitive exclusion. In order to allow for competitive exclusion — or for stabilization — the (...)
    Direct download (2 more)  
     
    My bibliography  
     
    Export citation  
  12. Ian Walker (1982). Miracles and Violations. International Journal for Philosophy of Religion 13 (2):103 - 108.
  13. I. Walker (1979). The Mechanical Properties of Proteins Determine the Laws of Evolutionary Change. Acta Biotheoretica 28 (4):239-282.
    The general inorganic nature of traditional selection theory (based on differential growth between any two systems) is pointed out, wherefrom it follows that this theory cannot provide explanations for the characteristics of organic evolution. Specific biophysical aspects enter with the complexity of macro-molecules: vital physical conditions for the perpetuation of the system, irrevocable extinction (= death) and random change leading to novelty, are the result of complexity per se. Further biophysical properties are a direct function of the pathway along which (...)
    Direct download (2 more)  
     
    My bibliography  
     
    Export citation  
  14. I. Walker (1978). The Evolution of Sexual Reproduction as a Repair Mechanism. Part I. A Model for Self-Repair and its Biological Implications. Acta Biotheoretica 27 (3-4):133-158.
    The theory is presented that the sexual process is a repair mechanism which maintains redundancy within the sub-structure of hierarchical, self-reproducing organisms. In order to keep the problems within mathematically tractable limits , a simple model is introduced: a wheel with 6 spokes, 3 of them vital and 3 redundant, symbolizes the individual . Random accidents destroy spokes; the wheels replicate at regular cycles and engage periodically in pairing and repair phases during which missing spokes are copy-reproduced along the intact (...)
    Direct download (2 more)  
     
    My bibliography  
     
    Export citation  
  15. R. M. Williams & I. Walker (1978). The Evolution of Sexual Reproduction as a Repair Mechanism Part II. Mathematical Treatment of the Wheel Model and its Significance for Real Systems. Acta Biotheoretica 27 (3-4):159-184.
    The dynamics of populations of self-replicating, hierarchically structured individuals, exposedto accidents which destroy their sub-units, is analyzed mathematically, specifically with regardto the roles of redundancy and sexual repair. The following points emerge from this analysis:0 A population of individuals with redundant sub-structure has no intrinsic steady-statepoint; it tends to either zero or infinity depending on a critical accident rate α c . Increased redundancy renders populations less accident prone initially, but populationdecline is steeper if a is greater than a fixed (...)
    Direct download (2 more)  
     
    My bibliography  
     
    Export citation  
  16. I. Walker (1976). Maxwell's Demon in Biological Systems. Acta Biotheoretica 25 (2-3):103-110.
    Boltzmann's gas model representing the second law of thermodynamics is based on the improbability of certain molecular distributions in space. Maxwell argued that a hypothetical ‘being’ with the faculty of seeing individual molecules could bring about such improbable distributions, thus violating the law of entropy. However, it appears that to render the molecules visible for any observer would increase the entropy more than the demon could decrease it, hence ‘Maxwell's Demon cannot operate’ . In the study presented here Maxwell's Demon (...)
    Direct download (2 more)  
     
    My bibliography  
     
    Export citation  
  17. I. Walker & R. M. Williams (1976). The Evolution of the Cooperative Group. Acta Biotheoretica 25 (1):1-43.
    A simple model, illustrating the transition from a population of free swimming, solitary cells to one consisting of small colonies serves as a basis to discuss the evolution of the cooperative group. The transition is the result of a mutation of the dynamics of cell division, delayed cell separation leads to colonies of four cells. With this mutation cooperative features appear, such as synchronised cell divisions within colonies and coordinated flagellar function which enables the colony to swim in definite directions. (...)
    Direct download (2 more)  
     
    My bibliography  
     
    Export citation  
  18. Ilse Walker (1972). Biological Memory. Acta Biotheoretica 21 (3-4):203-235.
    A specific mapping mechanism is defined as the basic unit of “Biological Memory”. This mechanism must account for the characteristic frequency patterns in the organic world, where future probability is a function of past experience. The conditions for the function of biological memory are analysed. It is found that asymmetry, and irreversibility as a consequence of complexity, are the basic principles of memory function. The essential asymmetries in genetic memory are pointed out, and the problem of bilateral symmetry in a (...)
    Direct download (2 more)  
     
    My bibliography  
     
    Export citation