Metrópoli real y aldea letrada: las luchas por la hegemonía literaria en la Ciudad de México

in Schneier, Gabriela (Ed.) Consommation urbaine de produits culturels (1991)

Choix de l'habitat par le lynx européen et par sa proie principale, le chevreuil, dans un milieu de moyenne montagne (massif vosgien). 1. le cas du chevreuil

in Cahiers d'Ethologie (1991), 11(1), 51-66

Since 1983, 12 lynxes were reintroduced in the forests of Eastern France (massif des Vosges). They use their habitat in a patchy way. In this part, the authors deal with the ecological distridution of ... [more ▼]

Since 1983, 12 lynxes were reintroduced in the forests of Eastern France (massif des Vosges). They use their habitat in a patchy way. In this part, the authors deal with the ecological distridution of their main prey, the roe deer. It is to see to what extent the prey distribution can influence the predator habits. Roe deer observations were made during 4 consecutive springs and 3 consecutive summers and related with the environmental characteristics of the forest plots: physiographical factors, vegetation type, vegetation structure, relative cover of vegetation layer... Eight discriminant analysis were performed. They suggest that in our study area, the roe deer spatial distribution is mainly influenced by the altitude and the non deciduous tree cover. Other factors of less importance are the global tree cover and the understory (scrub layer). Moreover it seems that the presence of the red deer can also influence the roe deer habitat utilization. [less ▲]

Mesure de la dénitrification biologique potentielle dans les sols à l'aide de l'acétylène.

in Revue de l’Agriculture = Landbouwtijdschrift (1991), 44(4), 637-648

De nombreuses méthodes ont été établies pour quantifier et définir la cinétique de dénitrification mais elles se sont toutes confrontées à la difficulté de doser l'azote de l'air (N2) qui est l'élément ... [more ▼]

De nombreuses méthodes ont été établies pour quantifier et définir la cinétique de dénitrification mais elles se sont toutes confrontées à la difficulté de doser l'azote de l'air (N2) qui est l'élément terminal de la chaîne de Payne (1973) : NO3 → NO2 → NO → N2O → N2. L'utilisation de l'acétylène a résolu ce problème en permettant l'inhibition de la réduction de l'oxyde nitreux (N2O) en N2, l'oxyde nitreux étant facilement dosable par chromatographie gazeuse. La technique utilisée lors de ce travail consiste à prélever un échantillon de sol dans l'horizon de surface. Après homogénéisation, il est placé dans des fioles à pénicilline hermétiques de 120 ml. Une préincubation de 50 h à 20-22° C sous anaérobiose engendre l'élimination des nitrates endogènes présents au départ dans le sol, ce qui permet par la suite d'ajouter des quantités précises de nitrates en vue d'effectuer des bilans de transformation du NO3 en N2O. Cette préincubation est suivie d'une incubation sous air, en présence d'acétylène (10 % vol/vol), à 20° C et à 100 % de saturation en eau. Sous ces conditions, la production de N-N2O et la disparition de N-NO3 sont mesurées, permettant ainsi de quantifier les bilans de transformation. En reportant les résultats obtenus pour 1 ha de sol (pour les 20 premiers cm), 12 kg d'azote sur les 20 présents au départ ont dénitrifié sur une période de 5 jours. De plus, cette disparition suit une cinétique à allure précise. Si ces estimations s'avéraient correspondre à la réalité, les mécanismes en cause seraient alors de la plus grande importance, tant pour l'agriculture en améliorant l'utilisation de l'azote, que pour l'environnement et la pollution de l'air et de l'eau. [less ▲]

Pratique agricole en Lorraine belge et pollution des eaux par les nitrates.

in Harpes, J.-P. (Ed.) Actes du colloque Les problèmes environnementaux au Luxembourg et dans la grande région. (1991)

L'éducation des jeunes enfants au seuil de l'ère technologique

in Communication et Langages (1991), (89), 31-36

Decision Trees and Transient Stability of Electric Power Systems

in Automatica (1991), 27(1), 115-134

An inductive inference method for the automatic building of decision trees is investigated. Among its various tasks, the splitting and the stop splitting criteria successively applied to the nodes of a ... [more ▼]

An inductive inference method for the automatic building of decision trees is investigated. Among its various tasks, the splitting and the stop splitting criteria successively applied to the nodes of a grown tree, are found to play a crucial role on its overall shape and performances. The application of this general method to transient stability is systematically explored. Parameters related to the stop splitting criterion, to the learning set and to the tree classes are thus considered, and their influence on the tree features is scrutinized. Evaluation criteria appropriate to assess accuracy are also compared. Various tradeoffs are further examined, such as complexity vs number of classes, or misclassification rate vs type of misclassification errors. Possible uses of the trees are also envisaged. Computational issues relating to the building and the use of trees are finally discussed. [less ▲]

Variations saisonnières du régime alimentaire du chevreuil (Capreolus capreolus) en Haute Belgique

in Cahiers d'Ethologie (1991), 11(1), 17-30

In Belgium, information related to the deer food are quite uncommon and, as far as the roe deer is concerned, restricted to the hunting season (autumn). Our study was conducted in two areas of southern ... [more ▼]

In Belgium, information related to the deer food are quite uncommon and, as far as the roe deer is concerned, restricted to the hunting season (autumn). Our study was conducted in two areas of southern Belgium. The first, in Hotton (50°15 N, 5°27E) is a mixed oak-beech forest with a important cover of brambles. Faeces samples were collected monthly from October 1987 to September 1988. The second area, inside the Nature reserve of "Les Hautes Fagnes" (50°30N, 6°06 E; 600 m) is an old peat-bog (Eriophorum vaginatum, Molinia coerulea, Vaccinium myrtillus and V. uliginosum) surrounded by spruce plantations. Sampling took place there only in April and in June 1989. Faeces were boiled and filtered before digestion in the Scharrer- Kurschner mixture for 30 min. Then samples were sieved under water and a small amount taken and mounted on a slide for microscopic observation. More than 13,000 small vegetal pieces were identified to the species by comparison between the observed epidermal features and a reference collection of plant epidermis. Woody plants are the main food of the roe deer in both areas: in the Hautes Fagnes, heather (Calluna vulgaris) and bilberry (Vaccinium) are the main food items whereas in Hotton, brambles are the most important part the diet in each season. In Hotton, we found that the diet was much more diversified during the green season than in the winter. The winter diet comprises mainly brambles but also heather an Vaccinium myrtillus in low quantities. Spruce needles are present only at the end of the winter. In the spring, grasses were taken but their contribution to the food of the deer was never important. During the summer, the roe deer ate more tree leaves (Quercus robur and Sorbus aucuparia). In the Hautes Fagnes, grasses were important only in the spring diet and tree leaves (Sorbus) in the summer. Some tree species were very common in both study areas (beech and spruce saplings) but nearly not eaten. The roe deer can thus considered as a selective feeder preferring high quality foods (spring grasses or young leaves) to bulky one (old grasses or hard leaves). [less ▲]

La forêt et les forestiers : réalités, nouvelles approches et défis

Book published by Faculté des Sciences Agronomiques (1991)

In this paper, the author states his views concerning the objective notion of « multiple use » forests and the forest ecosystem itself. The role of the forester and the challenges facing him in both ... [more ▼]

In this paper, the author states his views concerning the objective notion of « multiple use » forests and the forest ecosystem itself. The role of the forester and the challenges facing him in both highly industrialized as well as developing countries are analyzed in the light of new approaches and concepts. Particular attention is focused on his role in the future and some of the points considered are : efforts to prevent depletion of natural resources, the integration of ecological, economic and sociological aspects in management practices, the decision making under risk situation. [less ▲]

Particularités physiologiques et physiopathologiques de la fonction pulmonaire des bovins

in Point Vétérinaire (1991), 23(140), 793-799

This review détails the specific factors of respiratory function in cattle, the purpose being to understand cattle's great sensitivity te respiratory conditions, to be able to breed them for an optimal ... [more ▼]

This review détails the specific factors of respiratory function in cattle, the purpose being to understand cattle's great sensitivity te respiratory conditions, to be able to breed them for an optimal functioning of their respiratory metabolism, and to adapt the prevention of respiratory conditions to the physiological specificity of this species. For each main respiratory syndrome, the consequences on the vital functions, and particularly for the respiratory function, are analyzed (9 tables, 33 references). [less ▲]

Conditional Heteroscedasticity in Stock Returns: International Evidence

E-print/Working paper (1991)