Searcharxiv⌕ Search

SEARCH · Searcharxiv

Results for “adap-org”

Search indexed arXiv papers on artificial intelligence, large language models, computer vision and robotics. Read source abstracts and follow links to arXiv.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6Linked to original sources
arXiv1999

Simple models of evolution and extinction

This article gives a brief introduction to the mathematical modeling of large-scale biological evolution and extinction. We give three examples of simple models in this field: the coevolutionary avalanche model of Bak and Sneppen, the environmental stress model of Newman, and the increasing fitness model of Sibani, Schmidt, and Alstrom. We describe the features of real evolution which these models are intended to explain and compare the results of simulations against data drawn from the fossil record.

adap-org↗
arXiv1999

Mathematical description of the heat transfer in living tissue (Part I)

In the present monograph we formulate a simple model for heat transfer in living tissue with self - regulation. The initial point of the model is the governing equations describing heat transfer in living tissue at the mesoscopic level, i.e. considering different vessels individually. Then, basing on the well known equivalence of the diffusion type process and random walks, we develop a certain regular procedure that enables us to average these mesoscopic equations practically over all scales of the hierarchical vascular network. The microscopic governing equations obtained in this way describe living tissue in terms of an active medium with continuously distributed self - regulation. One of the interesting results obtained in the present monograph is that there can be the phenomena of ideal self - regulation in large active hierarchical systems. Large hierarchical systems are characterized by such a great information flow that none of its elements can possess whole information required of governing the system behavior. Nevertheless, there exists a cooperative mechanism of regulation which involves individual response of each element to the corresponding hierarchical piece of information and leads to ideal system response due to self - processing of information. The particular results are obtained for bioheat transfer. However, self - regulation in other natural hierarchical systems seems to be organized in a similar way. The characteristics of large hierarchical systems occurring in nature are discussed from the stand point of regulation problems. By way of example, some ecological and economic systems are considered. An cooperative mechanism of self-regulation which enables the system to function ideally is proposed.

adap-org↗
arXiv1999

Mathematical description of the heat transfer in living tissue (Part II)

In the present monograph we formulate a simple model for heat transfer in living tissue with self - regulation. The initial point of the model is the governing equations describing heat transfer in living tissue at the mesoscopic level, i.e. considering different vessels individually. Then, basing on the well known equivalence of the diffusion type process and random walks, we develop a certain regular procedure that enables us to average these mesoscopic equations practically over all scales of the hierarchical vascular network. The microscopic governing equations obtained in this way describe living tissue in terms of an active medium with continuously distributed self - regulation. One of the interesting results obtained in the present monograph is that there can be the phenomena of ideal self - regulation in large active hierarchical systems. Large hierarchical systems are characterized by such a great information flow that none of its elements can possess whole information required of governing the system behavior. Nevertheless, there exists a cooperative mechanism of regulation which involves individual response of each element to the corresponding hierarchical piece of information and leads to ideal system response due to self - processing of information. The particular results are obtained for bioheat transfer. However, self - regulation in other natural hierarchical systems seems to be organized in a similar way. The characteristics of large hierarchical systems occurring in nature are discussed from the stand point of regulation problems. By way of example, some ecological and economic systems are considered. An cooperative mechanism of self-regulation which enables the system to function ideally is proposed.

adap-org↗
arXiv2002

Amplifying Phenomenal Information: Toward a Fundamental Theory of Consciousness

Fundamental approaches bypass the problem of getting consciousness from non-conscious components by positing that consciousness is a universal primitive. For example, the double aspect theory of information holds that information has a phenomenal aspect. How then do you get from phenomenal information to human consciousness? This paper proposes that an entity is conscious to the extent it amplifies information, first by trapping and integrating it through closure, and second by maintaining dynamics at the edge of chaos through simultaneous processes of divergence and convergence. The origin of life through autocatalytic closure, and the origin of an interconnected worldview through conceptual closure, induced phase transitions in the degree to which information, and thus consciousness, is locally amplified. Divergence and convergence of cognitive information may involve phenomena observed in light e.g. focusing, interference, and resonance. By making information flow inward-biased, closure shields us from external consciousness; thus the paucity of consciousness may be an illusion.

adap-org↗
arXiv1999

Modelling Migration and Economic Agglomeration with Active Brownian Particles

We propose a stochastic dynamic model of migration and economic aggregation in a system of employed (immobile) and unemployed (mobile) agents which respond to local wage gradients. Dependent on the local economic situation, described by a production function which includes cooperative effects, employed agents can become unemployed and vice versa. The spatio-temporal distribution of employed and unemployed agents is investigated both analytically and by means of stochastic computer simulations. We find the establishment of distinct economic centers out of a random initial distribution. The evolution of these centers occurs in two different stages: (i) small economic centers are formed based on the positive feedback of mutual stimulation/cooperation among the agents, (ii) some of the small centers grow at the expense of others, which finally leads to the concentration of the labor force in different extended economic regions. This crossover to large-scale production is accompanied by an increase in the unemployment rate. We observe a stable coexistence between these regions, although they exist in an internal quasistationary non-equilibrium state and still follow a stochastic eigendynamics.

adap-org↗
arXiv1999

Fitness versus Longevity in Age-Structured Population Dynamics

We examine the dynamics of an age-structured population model in which the life expectancy of an offspring may be mutated with respect to that of the parent. While the total population of the system always reaches a steady state, the fitness and age characteristics exhibit counter-intuitive behavior as a function of the mutational bias. By analytical and numerical study of the underlying rate equations, we show that if deleterious mutations are favored, the average fitness of the population reaches a steady state, while the average population age is a decreasing function of the overall fitness. When advantageous mutations are favored, the average population fitness grows linearly with time t, while the average age is independent of fitness. For no mutational bias, the average fitness grows as t^{2/3}.

adap-org↗
arXiv1996

A Two--Exponent Mass-Size Power Law for Celestial Objects

The Universe that we know is populated by structures made up of aggregated matter that organizes into a variety of objects; these range from stars to larger objects, such as galaxies or star clusters, composed by stars, gas and dust in gravitational interaction. We show that observations support the existence of a composite (two--exponent) power law relating mass and size for these objects. We briefly discuss these power laws and, in view of the similarity in the values of the exponents, ponder the analogy with power laws in other fields of science such as the Gutenberg--Richter law for earthquakes and the Hutchinson--MacArthur or Damuth laws of ecology. We argue for a potential connection with avalanches, complex systems and punctuated equilibrium, and show that this interpretation of large scale--structure as a self--organized critical system leads to two $predictions$: (a) the large scale structures are fractally distributed and, (b), the fractal dimension is $1.65 \pm 0.25$. Both are borne out by observations.

astro-ph↗
arXiv1993

Diversity and Collective Action

We elucidate the dynamics of ongoing collective action among intentional agents with diverse beliefs and imperfect information. Their decisions on whether or not to contribute to the collective good depend not only on the past but also on their expectations as to how their actions will affect those of others. We show that in attempts at collective action the onset of overall cooperation can take place in a sudden and unexpected way. Likewise, defection can appear out of nowhere in very large, previously cooperating groups. These outbreaks mark the end of long transient states in which defection or cooperation persists in groups that cannot sustain it indefinitely. Diversity of beliefs among individuals acts as an additional source of uncertainty and instigates the outbreaks.

chao-dyn↗
arXiv1993

Noise-Induced Linearisation and Delinearisation

It is demonstrated, by means of analogue electronic simulation and theoretically, that external noise can markedly change the character of the response of a nonlinear system to a low-frequency periodic field. In general, noise of sufficient intensity {\it linearises} the response. For certain parameter ranges in particular cases, however, an increase in the noise intensity can sometime have the opposite effect and is shown to {\it delinearise} the response. The physical origins of these contrary behaviours are discussed.

chao-dyn↗
arXiv1993

The Limits of Mathematics---Course Outline and Software

A remarkable new definition of a self-delimiting universal Turing machine is presented that is easy to program and runs very quickly. This provides a new foundation for algorithmic information theory. This new universal Turing machine is implemented via software written in Mathematica and C. Using this new software, it is now possible to give a self-contained ``hands on'' mini-course presenting very concretely the latest proofs of the fundamental information-theoretic incompleteness theorems.

chao-dyn↗
arXiv1998

Low dimensional travelling interfaces in coupled map lattices

We study the dynamics of the travelling interface arising from a bistable piece-wise linear one-way coupled map lattice. We show how the dynamics of the interfacial sites, separating the two superstable phases of the local map, is finite dimensional and equivalent to a toral map. The velocity of the travelling interface corresponds to the rotation vector of the toral map. As a consequence, a rational velocity of the travelling interface is subject to mode-locking with respect to the system parameters. We analytically compute the Arnold's tongues where particular spatio-temporal periodic orbits exist. The boundaries of the mode-locked regions correspond to border-collision bifurcations of the toral map. By varying the system parameters it is possible to increase the number of interfacial sites corresponding to a border-collision bifurcation of the interfacial attracting cycle. We finally give some generalizations towards smooth coupled map lattices whose interface dynamics is typically infinite dimensional.

chao-dyn↗
arXiv1998

Stochastic Coherence in Coupled Map Lattices

We report in details the observations of structures in coupled map lattice during its chaotic evolution, both in one and two dimension, driven by identical noise on each site (by a structure we mean a group of neighboring lattice-sites for whom values of dynamical variable follow certain prespecified pattern). It is observed that the number of these structures decays with their size following a power-law, for a given noise-strength. The number of structures decays with their lifetime following a stretched exponential. We have seen an interesting phenomenon, which we call stochastic coherence, in which the average length as well as the average lifetime of these structures exhibit bell-shaped maxima for some intermediate range of noise-strength values. Similar features have also been observed for `spatio-temporal structures'.

chao-dyn↗
arXiv1998

Expansion-modificaction systems: an explanation for long range correlations in DNA

Based on a model first studied in [Physical Review A, vol. 43, 5240-5260,1991] properties of correlation function for expansion-modification systems are developed. The existence of several characteristic exponents is proved. The relationship of this fact with long-range correlation in DNA is stablished. Comparison between theoretical exponents and those obtained from simulation and real sequences are also showed.

chao-dyn↗
arXiv1999

Restart Strategies and Internet Congestion

We recently presented a methodology for quantitatively reducing the risk and cost of executing electronic transactions in a bursty network environment such as the Internet. In the language of portfolio theory, time to complete a transaction and its variance replace the expected return and risk associated with a security, whereas restart times replace combinations of securities. While such a strategy works well with single users, the question remains as to its usefulness when used by many. By using mean field arguments and agent-based simulations, we determine that a restart strategy remains advantageous even if everybody uses it.

chao-dyn↗
arXiv1999

Noncommutative Martin-Lof randomness : on the concept of a random sequence of qubits

Martin-Lof's definition of random sequences of cbits as those not belonging to any set of constructive zero Lebesgue measure is reformulated in the language of Algebraic Probability Theory. The adoption of the Pour-El Richards theory of computability structures on Banach spaces allows us to give a natural noncommutative extension of Martin-Lof's definition, characterizing the random elements of a chain Von Neumann algebra. In the particular case of the minimally informative noncommutative alphabet our definition reduces to the definition of a random sequence of qubits.

chao-dyn↗
arXiv1999

Sensitive boundary condition dependence of noise-sustained structure

Sensitive boundary condition dependence (BCD) is reported in a convectively unstable system with noise, where the amplitude of generated oscillatory dynamics in the downstream depends sensitively on the boundary value. This BCD is explained in terms of the manner in which the co-moving Lyapunov exponent (characterizing the convective instability) decreases from upstream to downstream. It is shown that a fractal BCD appears if the dynamics that represent the spatial change of the fixed point includes transient chaotic dynamics. By considering as an example a one-way-coupled map lattice, this theory for BCD is demonstrated.

chao-dyn↗
arXiv1993

Identification of Continuous-Time Dynamical Systems: Neural Network Based Algorithms and Parallel Implementation

Time-delay mappings constructed using neural networks have proven successful in performing nonlinear system identification; however, because of their discrete nature, their use in bifurcation analysis of continuous-time systems is limited. This shortcoming can be avoided by embedding the neural networks in a training algorithm that mimics a numerical integrator. Both explicit and implicit integrators can be used. The former case is based on repeated evaluations of the network in a feedforward implementation; the latter relies on a recurrent network implementation. Here the algorithms and their implementation on parallel machines (SIMD and MIMD architectures) are discussed.

comp-gas↗
arXiv1994

A Growth Model for Dna Evolution (submitted to Nature)

We introduce a simple model for DNA evolution. Using the method of Peng et al.$^1$, we investigate the fractal properties of the system. For small chains and chains of intermediate size we find a fractal exponent that indicates the existence of long-range correlations, as in real DNA sequences. However, when very large chains are studied the fractal exponent asymptotically converge to the value of a random sequence. We verify that the mutations are responsible for the apparent existence of long-range correlations.

cond-mat↗