The Latin conscius does not translate anything like mind or consciousness. Only in the mid-nineteenth century do we find the first attempts to study consciousness as its own discipline. Wundt, James, and Freud disagreed about how to approach the science of consciousness, although agreeing that psychology was a 'science of consciousness' that takes lived biological experience as its object. The behaviorists vetoed this idea. By the 1950s, for cognitive science, mind (conscious and unconscious) was considered analogous to computer software. Recently, (...) the science of consciousness has returned as Consciousness Studies, a new interdisciplinary synthesis of neuroscience, psychology, philosophy, and cultural anthropology. But what is new in this renaissance of the science of consciousness? New first, second and third person approaches all propose to take consciousness itself as a variable. This approach is as controversial as the nineteenth-century science of consciousness--controversy perhaps inherent to any science of consciousness. (shrink)
We give in this paper indications about the dynamical impact (as phenotypic changes) coming from the main sources of perturbation in biological regulatory networks. First, we define the boundary of the interaction graph expressing the regulations between the main elements of the network (genes, proteins, metabolites, ...). Then, we search what changes in the state values on the boundary could cause some changes of states in the core of the system (robustness to boundary conditions). After, we analyse the role of (...) the mode of updating (sequential, block sequential or parallel) on the asymptotics of the network, essentially on the occurrence of limit cycles (robustness to updating methods). Finally, we show the influence of some topological changes (e.g. suppression or addition of interactions) on the dynamical behaviour of the system (robustness to topology perturbations). (shrink)
Ce texte a déjà paru sur Techno-science.net. Des chercheurs découvrent la formule mathématique du rythme et avancent que notre cerveau pourrait être câblé pour y répondre. Une nouvelle étude montre que tout compositeur, de Bach à Brubeck, répète des motifs rythmiques, de sorte que la partie reproduit le tout. Une équipe de recherche dirigée par les neuroscientifiques Daniel Levitin et Vinod Menon, respectivement des universités McGill et Stanford, a analysé les partitions de quelque 2 000 compositions (...) - Mathématiques – (...) Nouvel article. (shrink)
We classify actions of groups of finite Morley rank on abelian groups of Morley rank 2: there are essentially two, namely the natural actions of SL(V) and GL(V) with V a vector space of dimension 2. We also prove an identification theorem for the natural module of SL₂ in the finite Morley rank category.
This study assesses the impact had by institutional isomorphic pressures in the organisational fields of 185 businesses operating within the United Kingdom. The emphasis throughout is on how external institutions affect the socially and environmentally responsible aspects of an organization’s purchasing practice. Factor analyses and a linear regression model are employed to test the influence of these pressures. Initial findings suggest that what other industry participants are doing in this area is not as important in affecting the procurement practice of (...) the focal organisation as is the managers’ perception of how legitimacy is awarded by stakeholders and, indeed, if competitors with well-developed social and environmental supply chain management programs are perceived favourably in the industry. (shrink)
Building a meaningful model of biological regulatory network is usually done by specifying the components (e.g. the genes) and their interactions, by guessing the values of parameters, by comparing the predicted behaviors to the observed ones, and by modifying in a trial-error process both architecture and parameters in order to reach an optimal fitness. We propose here a different approach to construct and analyze biological models avoiding the trial-error part, where structure and dynamics are represented as formal constraints. We apply (...) the method to Hopfield-like networks, a formalism often used in both neural and regulatory networks modeling. The aim is to characterize automatically the set of all models consistent with all the available knowledge (about structure and behavior). The available knowledge is formalized into formal constraints. The latter are compiled into Boolean formula in conjunctive normal form and then submitted to a Boolean satisfiability solver. This approach allows to formulate a wide range of queries, expressed in a high level language, and possibly integrating formalized intuitions. In order to explore its potential, we use it to find cycles for 3-nodes networks and to determine the flower morphogenesis regulatory network of Arabidopsis thaliana . Applications of this technique are numerous and concern the building of models from data as well as the design of biological networks possessing specified behaviors. (shrink)
Mucoidy and cytotoxicity arise from two independent modifications of the phenotype of the bacterium Pseudomonas aeruginosa that contribute to the mortality and morbidity of cystic fibrosis. We show that, even though the transcriptional regulatory networks controlling both processes are quite different from a molecular or mechanistic point of view, they may be identical from a dynamic point of view: epigenesis may in both cases be the cause of the acquisition of these new phenotypes. This was highlighted by the identity of (...) formal graphs modelling these networks. A mathematical framework based on formal methods from computer science was defined and implemented with a software environment. It allows an easy and rigorous validation and certification of these models and of the experimental methods that can be proposed to falsify or validate the underlying hypothesis. (shrink)