Showing papers by "University of Grenoble published in 1990"
TL;DR: A complex sequence of pyroclastic flows and surges erupted by Nevado del Ruiz volcano on 13 November 1985 interacted with snow and ice on the summit ice cap to trigger catastrophic lahars (volcanic debris flows), which killed more than 23,000 people living at or beyond the base of the volcano.
361 citations
TL;DR: It is shown that when Bloch walls become chiral, they move with a velocity simply related to their chirality, which is a straightforward consequence of nonvariational effects, which are typical of nonequilibrium systems.
Abstract: At equilibrium, Bloch walls are chiral interfaces between domains with different magnetization. Far from equilibrium, a set of forced oscillators can exhibit walls between states with different phases. In this Letter, we show that when these walls become chiral, they move with a velocity simply related to their chirality. This surprising behavior is a straightforward consequence of nonvariational effects, which are typical of nonequilibrium systems.
239 citations
138 citations
TL;DR: Cell walls were isolated from the brown algae Pelvetia canaliculata, Fucus vesiculosus, Sargassum muticum (Fucales) and Laminaria digitata (Laminariales) and then submitted to sequential chemical extraction to identify fucans present in a continuous spectrum of compounds.
120 citations
TL;DR: In this article, it was shown that every strongly q-complete subvariety of a complex analytic space has a fundamental system of strongly qcomplete neighborhoods, and that L-cohomology theory readily implies Ohsawa's Hodge decomposition and Lefschetz isomorphism theorems.
Abstract: — It is shown that every strongly q–complete subvariety of a complex analytic space has a fundamental system of strongly q–complete neighborhoods. As a consequence, we find a simple proof of Ohsawa’s result that every non compact irreducible n–dimensional analytic space is strongly n–complete. Finally, it is shown that L–cohomology theory readily implies Ohsawa’s Hodge decomposition and Lefschetz isomorphism theorems for absolutely q–convex manifolds.
120 citations
110 citations
TL;DR: In this article, the authors used three-dimensional relocation techniques to locate more than 800 tremors with magnitudes ranging from 1.0 to 4.2, in a small volume near a major gas field (Lacq, France).
Abstract: Ten years of seismic recording allows us to locate more than 800 tremors with magnitudes ranging from 1.0 to 4.2, in a small (10 by 10 by 5 km) volume near a major gas field (Lacq, France). The seismic activity began 10 yr after gas extraction began. Nearly all of the epicenters are located within the lateral extent of the gas field. The only perturbation of the stress or strain fields, which has the same spatial and temporal scale as the seismicity, is the 500-bar drop in gas pressure due to 20 yr of gas exploitation, demonstrating that these events are induced. The network, established to monitor this activity, consists of eight telemetered stations including a well-bottom geophone located at 3200 m depth. Using three-dimensional relocation techniques, we computed new hypocenter positions for more than 280 events. These better-located hypocenters form a diffuse zone that mimics the local dome structure. Taking the regional tectonic stresses into account, we suggest that these ruptures may be the result of unfolding of the dome structure.
104 citations
TL;DR: The results of the KAO observations have confirmed its unusual nature: the far-infrared bands of ice are by far the strongest known as discussed by the authors, and its dust temperature, 50 K or less, is the lowest known for a late-type circumstellar envelope.
Abstract: IRAS 09371 + 1212 is still an absolutely unique object. This M giant star, with circumstellar CO and a spectacular bipolar nebula, displays unique IRAS FIR colors which had been attributed to strong emission in the 40-70-micron bands of ice, as subsequently supported by the observation of a strong 3.1-micron absorption band. The results of the KAO observations have confirmed its unusual nature: the far-infrared bands of ice are by far the strongest known. Its dust temperature, 50 K or less, is by far the lowest known for a late-type circumstellar envelope.
75 citations
TL;DR: A comparison of aerial and ground photographs taken before and after the 1985 Nevado del Ruiz eruption showed that about 16% to 30% of the surface area of the ice and snow was lost as discussed by the authors.
74 citations
TL;DR: The Nevado del Ruiz volcano has a 1.8m.m.y.-long eruptive record that includes alternate construction and destruction of three edifices during three main eruptive periods, termed as Ancestral Ruiz, Older Ruiz and Ruiz as discussed by the authors.
62 citations
TL;DR: In this paper, an algorithm that uses two sequential SAR digital images to measure the opening and closing of sea ice leads is introduced, and the methods used to analyze the SAR images are described, including the mesh of tie points and the classification of leads and ice.
Abstract: An algorithm that uses two sequential SAR digital images to measure the opening and closing of sea ice leads is introduced. The methods used to analyze the SAR images is described, including the mesh of tie points and the classification of leads and ice. The results of the anaylsis are compared with independent manual measurements, showing that the cells covering each lead are best interpreted as opening or closing in a group, rather than individually. Also, consideration is given to an automated algorithm for grouping cells, the possibility of simplifying the method, and the relationship between the opening and closing measurements and the theory of their parametric relation to mean deformation.
TL;DR: A procedure to interpret hydrochemical data based on a combined use of factor analysis (correspondence analysis) and Piper's classification principle is outlined and applied to the study of a multi-reservoir hydrothermal system (Allevard) located in the French Western Alps as mentioned in this paper.
TL;DR: This study confirms the predominance of alternate meiotic segregation in Robertsonian translocation carriers and points out the low incidence of imbalance in the sperm of Robertsonia translocation carrier and the lack of evidence for an interchromosomal effect.
Abstract: Meiotic segregation was studied in a male heterozygous for a 13;15 Robertsonian translocation using in vitro sperm penetration of hamster eggs. Sixty-seven sperm chromosome complements were obtained and R-banded. Alternate segregation produced equal numbers of normal (31) and balanced (29) gametes, as was theoretically expected. Incidence of unbalanced complements was 10.4%, and the frequency of abnormalities unrelated to the translocation was 7.4%. This study confirms the predominance of alternate meiotic segregation in Robertsonian translocation carriers. Four sperm studies of Robertsonian translocation have been previously reported. A review of the combined results points out the low incidence of imbalance in the sperm of Robertsonian translocation carrier and the lack of evidence for an interchromosomal effect.
TL;DR: In this paper, the authors define an algebraically closed field k and a quiver Q without oriented cycles, whose vertex set Q, identified with { 1,... n}. For a in the set Q of arrows of Q, they denote by ta and ha the tail and head of a, respectively.
TL;DR: In this article, Frank and Tardos give a good characterization of the minimum weights of paths from a fixed vertex of an undirected graph without negative circuits and a canonical packing of odd cuts with favorable properties.
Book•
01 Jul 1990TL;DR: This introductory text by a leading French computer scientist unfolds the organization of operating systems in the field of shared memory systems (or "centralized" systems) for which design principles are now reasonably stable.
Abstract: "Principles of Operating Systems" is unique among current texts on operating systems in its balanced treatment of principles and their application. It is comprehensive and offers richly detailed algorithms at every stage using the familiar Pascal-like notation; it covers basic computer mechanisms, and provides a variety of thoughtful and challenging exercises.This introductory text by a leading French computer scientist unfolds the organization of operating systems in the field of shared memory systems (or "centralized" systems) for which design principles are now reasonably stable. Its analysis of these principles is the most rigorous and complete available: basic concepts such as programs execution mechanisms, modular and hierarchical decomposition, interfaces, parallel processes, synchronization principles, information management, resources and memory allocation, and multiprogramming are covered in detail, and recent developments in the field of distributed systems are considered as well.Krakowiak illustrates the application of these principles in simplified examples from real systems - including CP/M for an overview of a microcomputer system, the Multics system for its addressing and linking scheme, the Plessey 250 for capabilities, Unix for its file system and process management - that will make it easier for readers to study a full-blown system by providing guidelines for analyzing and identifying its essential features. Some of the chapter exercises cover direct applications of the concepts discussed, others require design work and can form the basis of a project, while still others are intended to encourage investigation into aspects not covered in the book and provide annotated references.Contents: Introduction. Execution and Communication Mechanisms. Organization of a Simple Operating System. Management of Parallel Activities. Implementation of Synchronization Mechanisms. Naming, Storing, and Linking Objects. File Systems. Resource Allocation. Memory Management. Structure of a Multiprogrammed System. Introduction to Distributed Systems.Sacha Krakowiak is a professor at Grenoble University.
TL;DR: The 245th Euromech Colloquium on the effect of background rotation on fluid motions was held in Cambridge from 10-13 April 1989 with the two authors acting as chairmen as discussed by the authors.
Abstract: The 245th Euromech Colloquium, on the effect of background rotation on fluid motions, was held in Cambridge from 10–13 April 1989 with the two authors acting as chairmen. There were sixty-five participants with widely different backgrounds. The striking feature of the Colloquium was the recent advances on nonlinear processes. A wide range of nonlinear phenomena was presented and particular emphasis was on the formation and dynamics of coherent vortices. The similarities between the processes in rotating, curved and stratified flows, which lead to anisotropic motions and long-lived coherent structures alongside linear wave motions was a feature of many of the presentations. Fifty-one papers were presented, covering engineering, geophysical and astrophysical applications of rotating fluids. These papers are summarized in this report with the purpose of giving an up-to-date view of current research in rotating fluids.
TL;DR: For any pair of lattices L and L satisfying i)L⊂L and ii) the indexN of L into L is prime to 6, the authors construct from the usual φ-function of L(cf. no 1) some elliptic function.
Abstract: For any pair of latticesL andL satisfying i)L⊂L and ii) the indexN ofL intoL is prime to 6, we construct from the usual φ-function ofL(cf. no 1) some elliptic function
$$\psi = \psi (z;L,\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{L} )$$
of the variablez, with period latticeL, and divisor
$$N(0)_L - \sum\limits_{i - 1}^N {(t_i )_L } $$
over the torus ℂL, where the complex numbersti, 1≦i≦N, describe a complete set of representatives of the quotientL/L.
TL;DR: In this article, Dodziuk and Elworthy give an extension of Bochner's vanishing theorem to complete manifolds, which generalizes earlier results of J.D., K.D. and S. Rosenberg.
Abstract: In this note we give an extension of Bochner's vanishing theorem to complete manifolds; this generalizes earlier results of J. Dodziuk, K.D. Elworthy and S. Rosenberg.
TL;DR: In this paper, the authors interpreted the textural heterogeneity of juvenile products of the Nevado del Ruiz (Colombia) volcano as a result of transfers of phenocrysts by a mechanical mixing process, mainly from the felsic component to the mafic one.
TL;DR: In this article, a condition suffisante est optimale: nous construisons des courants de bidegre (1, 1) n'ayant pas de cone tangent, tels que l'integrale de (vT(r)−vT (0))/r soit aussi peu divergente qu'on le souhaite.
Abstract: SoitT un courant positif ferme sur un voisinage de 0 dansCn. Nous montrons queT admet un cone tangent (limite de la famille de ses homothetiques), des que les masses projectivesvT(r) convergent assez vite versVT(0) pour que (vT(r)−vT(0))/r soit localement sommable enr=0. Cette condition suffisante est optimale: nous construisons des courants de bidegre (1, 1) n'ayant pas de cone tangent, tels que l'integrale de (vT(r)−vT(0))/r soit aussi peu divergente qu'on le souhaite. LorsqueT est le courant d'integration sur un ensemble analytique, on verifie quevT(r)−vT(0)=0re), ce qui redonne le theoreme de Thie-King sur l'existence du cone tangent.
TL;DR: The latest Ruiz eruptions that involved rockslide-debris avalanches resemble in part the Shiveluch 1964 event for which evidence of lateral blast deposits are lacking as mentioned in this paper.
TL;DR: In this paper, the authors examined the harminization of petroleum product taxes in the European Community (EC) and argued that average tax levels may not be the best way of fulfilling the community's energy and environmental goals.
TL;DR: In this paper, a damage study has shown that site effects at different scales have played an important role in amplifying the effects of a moderate magnitude (Ml=4.9) earthquake.
Abstract: On November 8, 1983, a moderate magnitude (Ml=4.9) earthquake struck Liege (Belgium). A damage study has shown that site effects at different scales have played an important role in amplifying grou...
TL;DR: In this article, the Schmitt-Pacheco model was used to predict the reaction time of both normal fission and fast fission in the Ne + Re system and the Ar + Ho reaction.
TL;DR: It is shown that various time reversible methods, in particular, Burg's algorithm, for autoregressive model estimation may be performed through the use of a simple sufficient statistic, which provides more efficient computation of the estimators.
Abstract: It is shown that various time reversible methods, in particular, Burg's algorithm, for autoregressive model estimation may be performed through the use of a simple sufficient statistic. This provides more efficient computation of the estimators. >
05 Nov 1990
TL;DR: A survey of the adequacies and inadequacies of the DBMS proposals at the beginning of this new decade is made and some example which can help to understand how the field is going to evolve is given.
Abstract: It is always a very difficult exercise to predict the future and we did not do that! Rather, we tried to make a survey of the adequacies and inadequacies of the DBMS proposals at the beginning of this new decade. We tried to adopt a practical point of view and we gave some example which can help to understand how the field is going to evolve. As we have seen, we left a lot of problems open. Some of them are going to be addressed by the papers of the other sessions, and several solutions will be given. There is a huge amount of work in research and development in order to have systems which are both easy to use and efficient. We believe more in the integration of several different fields (e.g. programming languages and databases) rather than in the emergence of completely new fields.