FUZZIFYING THE “PRECISE”

Based on the fuzzy-integral model, methods and algorithms are developed for identifying the “input–output” operator of continuous and stationary discrete extremal fuzzy dynamic systems (EFDS). The EFDS “input–output” operator is restored by means of experimental data with possibilistic uncertainty, the source of which is extremal fuzzy time intervals. The regularization conditions for obtaining quasi-optimal estimates are substantiated by the proved theorems. The corresponding algorithms are provided. The results obtained are illustrated by examples in the case of a finite set of EFDS states.     

SELF-ORGANIZATION OF LIVING SYSTEMS: A FORMAL MODEL OF AUTOPOIESIS

ABSTRACT

A formalization, computerization and extension of the original Varela-Maturana-Uribe model of autopoiesis is presented. Autopoietic systems are driven by sets of simple “rules” which guide the behavior of components in a given milieu. These rules are capable of producing systemic structures that are far more complex than we could ever achieve by a direct arrangement of components, i.e., by a method of systems analysis and design. The study of autopoietic systems indicates that the traditional emphasis on internal qualities of system's components has been misplaced. It is the organization of components, rather than the components themselves (or their structural manifestations), that provides the necessary and sufficient conditions of autopoiesis and thus of life itself. The dynamic autonomy of autopoietic systems contrasts significantly with the non-autonomous, allopoietic mechanistic systems.     

Fatigue behaviour of friction stir welded AA2024‐T3 alloy: longitudinal and transverse crack growth

The fatigue crack growth properties of friction stir welded joints of 2024‐T3 aluminium alloy have been studied under constant load amplitude (increasing‐ΔK), with special emphasis on the residual stress (inverse weight function) effects on longitudinal and transverse crack growth rate predictions (Glinka's method). In general, welded joints were more resistant to longitudinally growing fatigue cracks than the parent material at threshold ΔK values, when beneficial thermal residual stresses decelerated crack growth rate, while the opposite behaviour was observed next to K_C instability, basically due to monotonic fracture modes intercepting fatigue crack growth in weld microstructures. As a result, fatigue crack growth rate (FCGR) predictions were conservative at lower propagation rates and non‐conservative for faster cracks. Regarding transverse cracks, intense compressive residual stresses rendered welded plates more fatigue resistant than neat parent plate. However, once the crack tip entered the more brittle weld region substantial acceleration of FCGR occurred due to operative monotonic tensile modes of fracture, leading to non‐conservative crack growth rate predictions next to K_C instability. At threshold ΔK values non‐conservative predictions values resulted from residual stress relaxation. Improvements on predicted FCGR values were strongly dependent on how the progressive plastic relaxation of the residual stress field was considered.     

Basal cell carcinoma stem cells exhibit osteogenic and chondrogenic differentiation potential

Specific cell subpopulations identified as cancer stem cells (CSCs) can be found in basal cell carcinoma (BCC). Generally, CSCs have a marked trans-differentiation potential that could potentially be used in differentiation therapies. However, there are no studies regarding BCC CSCs multipotency. The aim of the study was to analyze the characteristic of CSCs of BCC with emphasis on their differentiation potential upon specific induction. Specific staining and cell morphology were used for differentiation confirmation, along with the expression analysis of osteogenic (ALP, BSP, Runx2, OCN, BMP2), chondrogenic (COL1 and COL2A1), adipogenic (PPAR-γ) and neurogenic (Nestin and MAP2) markers. BCC CSCs differentiated into osteogenic and chondrogenic lineages, as judged by staining and high expression of specific markers (from 2-to 92-fold higher upon induction). Concomitantly with differentiation, the levels of cancer stem cell markers decreased in the cultures. Adipo-differentiation and neuro-differentiation were unsuccessful. In conclusion, BCC CSCs exhibit the capacity to trans-differentiate, a characteristic that may potentially be useful in the development of new strategies for the treatment of aggressive BCCs.     

A review of “DESTINY AND CONTROL IN HUMAN SYSTEMS”, Studies in the Interactive Connectedness of Time (Chronotopology) by Charles Muses. Kluwer-Nijhoff Publishing,Boston-Dordrecht-Lancaster, 1985, 216 pages, $42.00.

Many complex self-organizing systems may not be easily modeled with the help of differential equations. Modern studies in complexity generated new kinds of modeling paradigms such as Cellular Automata (CA), Boolean Networks, and Multiagent Systems. Such models are built from large numbers of interacting units with simple behavior defined in terms of production rules. These models are capable of reproducing unexpected complex organization patterns where the character of the organization could not be derived from the character of the rules defining the behavior of units. Organization that is not evident from the dynamic rules is called emergent . The existence of emergent organization demonstrates the inadequacy of the traditionally accepted association of systems organization with the dynamic equation of the system. The main objective of the paper is to describe new General Systems Theory (GST) framework that gives appropriate account of new dimensions of organization and accommodates new approaches to modeling of complex adaptive systems (CAS). To describe system states and state sequences we use concept model from formal semantics. Dynamics of a system are described with the help of patterns or production rules. The isomorphism of systems is naturally represented as model isomorphism. The organization of a system is a set of formulae with free variables, which have interpretation on the models that represent the system. The framework introduced here is developed as a part of our eco-modeling project. We also discuss the architecture of ecological simulator, LEM (Logic for Eco-Modeling), and its implementation in Visual Prolog that serves as an example of practical application of the framework.     

Letters to the Editor

Abstract

We define an irreducible inconsistent system (IIS) such that every one of its proper subsystems is consistent. This study investigates the irreducibly inconsistent structures of all types of linear systems including equalities, inequalities and/or strict inequalities. By extending Loon's method, a quasi-simplex method is proposed to find the necessary and sufficient conditions on IIS's of these linear systems. Bused on these conditions, the criteria of IIS's are drawn and their relationship with IIS's of different linear systems can be surmised. Furthermore, the necessary and sufficient conditions of the inconsistency and. therefore, the criteria of an irreducibly inconsistent subsystem (IISS) of these linear systems are also proposed. In addition to the theoretical proofs, numerical examples are provided.

During the study, in order to reduce the computation efforts and memory spaces, particular attention is paid to the natural constraints where the variables are restricted on the positive orthant.

It is expected that this study may provide an access to the resolution of an inconsistent linear system.     

CYBERNETYKA

There is an increasing interest in the historical underpinnings of general systems theory and cybernetics. Alongside with Bogdanov, Leduc, Smuts, and similar “greats”, Bronistaw Trentowski stands as the sole father of cybernetyka, the science and art of managing a nation. In this paper we explore the relationship and contrasts between cybernetyka and cybernetics.