Fluctuations of a fortnightly abundance index of the Ivoirian coastal pelagic species and associated environmental conditions

Les auteurs analysent une série chronologique de prises par unité d'effort (PUE) de petites espèces pélagiques capturées de 1966 à 1982 au large de la Côte d'ivoire en fonction des températures de l'eau en surface (TES) relevées par les navires marchands. Ils ont utilisé un modèle à blancs pour déterminer les valeurs manquantes des PUE et des TES pour les pêcheries exploitées. Un modèle des séries chronologiques à plusieurs variables aléatoires pour des données bimensuelles permet d'expliquer 43 % de la variance observée des PUE obtenues de 1966 à 1982. A l'aide d'un modèle généré par les données recueillies de 1966 à 1980, ils ont obtenu des prévisions acceptables des PUE bimensuelles pour 1981-82. Une nouvelle approche pour l'estimation des transformations optimales des variables du modèle est utilisée pour étudier la relation entre les PUE et leurs éléments extrapolés. L'interprétation biologique des transformations estimées est en accord avec les résultats antérieurs sur la dynamique du zooplancton dans la même région. (Résumé d'auteur

Variable abstraction and approximations in supervisory control synthesis

This paper proposes a method to simplify Extended Finite-state Automata (EFA) in such a way the least restrictive controllable supervisor is preserved. The method is based on variable abstraction, which involves the identification and removal of irrelevant variables from a model. Variable abstraction preserves controllability, and the paper shows how approximations can be used to ascertain least restrictiveness of the synthesis result. The approach has the modelling benefits of Extended Finite-state Automata, leads to optimal control solutions, and reduces the synthesis cost. An example of a manufacturing system illustrates the contributions

Black-Hole Mass and Growth Rate at High Redshift

We present new H and K bands spectroscopy of 15 high luminosity active galactic nuclei (AGNs) at redshifts 2.3-3.4 obtained on Gemini South. We combined the data with spectra of additional 29 high-luminosity sources to obtain a sample with 10^{45.2}<\lambda L_{\lambda}(5100A)<10^{47.3} ergs/sec and black hole (BH) mass range, using reverberation mapping relationships based on the H_beta method, of 10^{8.8}-10^{10.7} M_sun. We do not find a correlation of L/L_Edd with M_BH but find a correlation with \lambda L_{\lambda}(5100A) which might be due to selection effects. The L/L_Edd distribution is broad and covers the range ~0.07-1.6, similar to what is observed in lower redshift, lower luminosity AGNs. We suggest that this consistently measured and calibrated sample gives the best representation of L/L_Edd at those redshifts and note potential discrepancies with recent theoretical and observational studies. The lower accretion rates are not in accord with growth scenarios for BHs at such redshifts and the growth times of many of the sources are longer than the age of the universe at the corresponding epochs. This suggests earlier episodes of faster growth at z>~3 for those sources. The use of the C IV method gives considerably different results and a larger scatter; this method seems to be a poor M_BH and L/L_Edd estimator at very high luminosity.Comment: 8 pages (emulateapj), 4 figures. Accepted for publication in Ap

Generalised verification of the observer property in discrete event systems

The observer property is an important condition to be satisfied by abstractions of Discrete Event Systems (DES) models. This paper presents a generalised version of a previous algorithm which tests if an abstraction of a DES obtained through natural projection has the observer property. The procedure called OP-verifier II overcomes the limitations of the previously proposed verifier while keeping its computational complexity. Results are illustrated by a case study of a transfer line system

Generalised verification of the observer property in discrete event systems

The observer property is an important condition to be satisfied by abstractions of Discrete Event Systems (DES) models. This paper presents a generalised version of a previous algorithm which tests if an abstraction of a DES obtained through natural projection has the observer property. The procedure called OP-verifier II overcomes the limitations of the previously proposed verifier while keeping its computational complexity. Results are illustrated by a case study of a transfer line system

Verification of the observer property in discrete event systems

The observer property is an important condition to be satisfied by abstractions of Discrete Event System (DES) models. This technical note presents a new algorithm that tests if an abstraction of a DES obtained through natural projection has the observer property. The procedure, called OP-Verifier, can be applied to (potentially nondeterministic) automata, with no restriction on the existence of cycles of 'non-relevant' events. This procedure has quadratic complexity in the number of states. The performance of the algorithm is illustrated by a set of experiments

Partial Order on the set of Boolean Regulatory Functions

Logical models have been successfully used to describe regulatory and signaling networks without requiring quantitative data. However, existing data is insufficient to adequately define a unique model, rendering the parametrization of a given model a difficult task. Here, we focus on the characterization of the set of Boolean functions compatible with a given regulatory structure, i.e. the set of all monotone nondegenerate Boolean functions. We then propose an original set of rules to locally explore the direct neighboring functions of any function in this set, without explicitly generating the whole set. Also, we provide relationships between the regulatory functions and their corresponding dynamics. Finally, we illustrate the usefulness of this approach by revisiting Probabilistic Boolean Networks with the model of T helper cell differentiation from Mendoza & Xenarios

Saving the present in Brazil: Perspectives from collaborations with indigenous museums

This paper explores some of the challenges and benefits involved in the collaboration between the Museum of Archaeology and Ethnology of the University of São Paulo, the India Vanuire Historical and Pedagogical Museum, and the Kaingang people of Vanuire, as well as some of the outcomes of these partnerships, such as the creation of the Kaingang Wowkriwig Museum. These experiences showed that working in collaboration with indigenous groups can be mutually beneficial and rewarding. The benefits include opportunities to empower the Kaingang to create and manage their own museums, and to exchange more effective preservation strategies, information about manufacturing technologies, as well as the original use and significance of objects. Moreover, the significance of objects whose value had diminished was revived by the new perspectives brought about by these inclusive approaches. The paper concludes that many other museums can act as agents of these processes but a prerequisite is a reconsideration of their relationships with indigenous groups and how the past can be redressed