Spectacles spécifiques : Critique, assomption et régression du spectaculaire dans le système de l’art contemporain

L’article attire l’attention sur un ensemble de pratiques artistiques qui relèvent de l’« intervention », de la « performance » et de l’« installation » et qui entendent déconstruire le spectacle des villes. Les interventions artistiques en milieu urbain remettent en question les catégories usuelles de l’art et du spectateur, mais aussi celles de l’action culturelle, de l’interaction et de la communauté. Partant de l’hypothèse générale que les « oeuvres d’art » – qui ne sont pas nécessairement des « objets » – sont des configurations signifiantes, on examine les discours critiques et esthétiques qui concourent à la définition du genre, puis les éléments clés du champ de l’intervention artistique : la revitalisation urbaine, les politiques culturelles, les réseaux artistiques, les nouveaux espaces publics et les formes de participation. L’article vise à démontrer que les artistes qui pratiquent l’intervention urbaine doivent directement faire face à la difficulté de penser le nouvel espace public et de le concrétiser.The paper studies a set of artistic practices stemming from “intervention,” “performance” and “installation,” and which aim to deconstruct the spectacle of cities. Artistic interventions in an urban setting defy the usual categories of art and the spectator, but also those of cultural action, interaction and the community. Starting with the general hypothesis that “works of art”–which are not necessarily “objects”–are significant configurations, a study is made of the critical and aesthetic discourses which contribute to the definition of the genre, and secondly of the key elements in the field of artistic intervention : urban renewal, cultural policies, artistic networks, new public spaces and forms of participation. The paper aims to show that the artists who work in an urban setting must face head-on the problem of defining the new public space and giving it concrete form.El artículo llama la atención sobre un conjunto de prácticas artísticas que son de la competencia de “la intervención”, de la “prestación” y de la “instalación”, y que pretenden desconstruir el espectáculo de las ciudades. Las intervenciones artísticas en medio urbano cuestionan las categorías usuales del arte y el espectador, y también las de la acción cultural, la interacción y la comunidad. A partir de la hipótesis general de que las “obras de arte”–que no son necesariamente “objetos”–son configuraciones significativas, se examinan los discursos críticos y estéticos que concurren en la definición del género, y los elementos claves del campo de la intervención artística : la revitalización urbana, las políticas culturales, las redes artísticas, los nuevos espacios públicos y las formas de participación. El artículo tiene por objeto demostrar que los artistas que practican la intervención urbana se enfrentan directamente a la dificultad de pensar el nuevo espacio público y de concretarlo

Was there an ‘Industrious Revolution’ before the Industrial Revolution? An Empirical Exercise for England, c. 1300-1830

It is conventionally assumed that the pre-modern working year was fixed and that consumption varied with changes in wages and prices. This is challenged by the twin theories of the ‘industrious’ revolution and the consumer revolution, positing a longer working year as people earned surplus money to buy novel goods. In this study, we turn the conventional view on its head, fixing consumption rather than labour input. Specifically, we use a basket of basic consumption goods and compute the working year of rural and urban day labourers required to achieve that. By comparing with independent estimates of the actual working year, we find two ‘industrious’ revolutions among rural workers; both, however, are attributable to economic hardship, and we detect no signs of a consumer revolution. For urban labourers, by contrast, a growing gap between their actual working year and the work required to buy the basket provides great scope for a consumer revolution.Consumer Revolution; Cost-of-Living Index; Day Wages; ‘Industrious’ Revolution; Industrial Revolution; Labour Supply; Standard of Living

Initial measurements of O-ion and He-ion decay rates observed from the Van Allen probes RBSPICE instrument.

H-ion (∼45 keV to ∼600 keV), He-ion (∼65 keV to ∼520 keV), and O-ion (∼140 keV to ∼1130 keV) integral flux measurements, from the Radiation Belt Storm Probe Ion Composition Experiment (RBSPICE) instrument aboard the Van Allan Probes spacecraft B, are reported. These abundance data form a cohesive picture of ring current ions during the first 9 months of measurements. Furthermore, the data presented herein are used to show injection characteristics via the He-ion/H-ion abundance ratio and the O-ion/H-ion abundance ratio. Of unique interest to ring current dynamics are the spatial-temporal decay characteristics of the two injected populations. We observe that He-ions decay more quickly at lower L shells, on the order of ∼0.8 day at L shells of 3-4, and decay more slowly with higher L shell, on the order of ∼1.7 days at L shells of 5-6. Conversely, O-ions decay very rapidly (∼1.5 h) across all L shells. The He-ion decay time are consistent with previously measured and calculated lifetimes associated with charge exchange. The O-ion decay time is much faster than predicted and is attributed to the inclusion of higher-energy (> 500 keV) O-ions in our decay rate estimation. We note that these measurements demonstrate a compelling need for calculation of high-energy O-ion loss rates, which have not been adequately studied in the literature to date.Key pointsWe report initial observations of ring current ionsWe show that He-ion decay rates are consistent with theoryWe show that O-ions with energies greater than 500 keV decay very rapidly

Sucrose versus maltose effect on metabolic pathways in somatic embryogenesis of Hevea brasiliensis

Somatic embryogenesis in Hevea is stimulated when the embryogenesis induction medium contains maltose, rather than glucose, fructose, or sucrose, in equimolarity (Blanc et al., 1999). Kinetic analyses were carried out on various physiological and biochemical indicators over the eight weeks that the induction phase then expression of somatic embryogenesis can take. Embryogenesis induction in the presence of glucose, fructose or sucrose revealed strong callus growth in the first 3-4 weeks, associated with a high intra and extracellular hexose content, a high starch content and a substantial decline in protein synthesis. Calli grown in the presence of maltose revealed uniform embryogenesis induction that was twice as fast. Their growth was slow and only half that seen with sucrose. This morphogenetic behaviour is associated with a drop in endogenous hexose and starch contents, and an increase in protein synthesis in the first three weeks of culture. At the end of culture, peroxidase activity, and membrane antioxidant and protein contents increased in these calli; these characteristics may be associated with somatic embryo organization and with the maintenance of effective membrane integrity within a nutrient environment that has become limiting. These new results tally with data in the literature on the roles of sugars, and provide some precise information with regard to the "carbohydrate deficit" hypothesis usually put forward to explain maltose action. An analysis of these results led to the hypothesis that regulation of endogenous hexose contents at a low level, through slow maltose hydrolysis, was a key element of the biochemical signal leading these calli towards somatic embryogenesis. (Texte intégral

L'encoche sèche chez Hevea brasiliensis

L'absence totale ou partielle d'écoulement du latex ou encoche sèche d'Hevea brasiliensis peut s'accompagner ou non de nécrose. S'il n'y en a pas, il s'agit le plus souvent d'une fatigue des laticifères et, après une période de repos, l'exploitation peut reprendre. L'encoche sèche nécrotique est une grave perturbation histologique, cytologique et métabolique, qui se traduit par une désorganisation profonde de tout le phloème secondaire et se propage en tous sens. Causée par des stress complexes, elle est le plus souvent irréversible. (Résumé d'auteur