59,481 research outputs found
Forest vegetation management: France (chap.4)
Current practices and problems of forest vegetation management in France are described in the context of research on alternatives to herbicides.FORET;PEUPLEMENT FORESTIER;VEGETATION;CONCURRENCE VEGETALE;LUTTE;MODE DE TRAITEMENT;LUTTE PHYTOSANITAIRE + MAUVAISE HERBE;CONTROLE DE LA VEGETATION;PESTICIDE;HERBICIDE;LUTTE PHYTOSANITAIRE;IMPACT SUR L'ENVIRONNEMENT;DYNAMIQUE DE VEGETATION;HISTOIRE;GESTION FORESTIERE;ECOSYSTEME;FRANCE;VEGETATION FORESTIERE;GESTION;ALTERNATIVES AUX HERBICIDES;ADVENTICE;SPECIES COMPOSITION
Temporal and Spatial Data Mining with Second-Order Hidden Models
In the frame of designing a knowledge discovery system, we have developed
stochastic models based on high-order hidden Markov models. These models are
capable to map sequences of data into a Markov chain in which the transitions
between the states depend on the \texttt{n} previous states according to the
order of the model. We study the process of achieving information extraction
fromspatial and temporal data by means of an unsupervised classification. We
use therefore a French national database related to the land use of a region,
named Teruti, which describes the land use both in the spatial and temporal
domain. Land-use categories (wheat, corn, forest, ...) are logged every year on
each site regularly spaced in the region. They constitute a temporal sequence
of images in which we look for spatial and temporal dependencies. The temporal
segmentation of the data is done by means of a second-order Hidden Markov Model
(\hmmd) that appears to have very good capabilities to locate stationary
segments, as shown in our previous work in speech recognition. Thespatial
classification is performed by defining a fractal scanning ofthe images with
the help of a Hilbert-Peano curve that introduces atotal order on the sites,
preserving the relation ofneighborhood between the sites. We show that the
\hmmd performs aclassification that is meaningful for the agronomists.Spatial
and temporal classification may be achieved simultaneously by means of a 2
levels \hmmd that measures the \aposteriori probability to map a temporal
sequence of images onto a set of hidden classes
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Individual learner differences and distance language learning: an overview
No abstract available
The emergence of French statistics. How mathematics entered the world of statistics in France during the 1920s
This paper concerns the emergence of modern mathematical statistics in France
after the First World War. Emile Borel's achievements are presented, and
especially his creation of two institutions where mathematical statistics was
developed: the {\it Statistical Institute of Paris University}, (ISUP) in 1922
and above all the {\it Henri Poincar\'e Institute} (IHP) in 1928. At the IHP, a
new journal {\it Annales de l'Institut Henri Poincar\'e} was created in 1931.
We discuss the first papers in that journal dealing with mathematical
statistics
Algebraic Change-Point Detection
Elementary techniques from operational calculus, differential algebra, and
noncommutative algebra lead to a new approach for change-point detection, which
is an important field of investigation in various areas of applied sciences and
engineering. Several successful numerical experiments are presented
A formal verification framework and associated tools for enterprise modeling : application to UEML
The aim of this paper is to propose and apply a verification and validation approach to Enterprise Modeling that enables the user to improve the relevance and correctness, the suitability and coherence of a model by using properties specification and formal proof of properties
Hedging Strategies in Forest Management
The paper focuses on forests management strategies for natural hazards of nonindustrial owners, in the case where the forest provides nontimber services. We introduce a basic two-period model where the private owner manages natural hazards on his forest thanks to the accumulation of savings on his individual income, or to the adoption of sylvicultural practices. We show that: 1/ the harvesting rule, in the presence of amenity services and a random growth rate for forest, is smaller than the one predicted under the Faustmann's rule; 2/ savings and sylvicultural pratices may be seen as perfectly substitutable tools for the management of natural hazards. However, our analysis predicts that the harvesting rule displays a specific sensibility to price effects and/or changes in the distribution of natural hazards, depending on whether forest owners opt for the financial strategy or undertake sylvicultural practices.Risk; Forest; Amenities; Savings and Sylvicultural Practices
Immunomodulation stimulates the innervation of engineered tooth organ
The sensory innervation of the dental mesenchyme is essential for tooth function and protection. Sensory innervation of the dental pulp is mediated by axons originating from the trigeminal ganglia and is strictly regulated in time. Teeth can develop from cultured re-associations between dissociated dental epithelial and mesenchymal cells from Embryonic Day 14 mouse molars, after implantation under the skin of adult ICR mice. In these conditions however, the innervation of the dental mesenchyme did not occur spontaneously. In order to go further with this question, complementary experimental approaches were designed. Cultured cell re-associations were implanted together with trigeminal ganglia for one or two weeks. Although axonal growth was regularly observed extending from the trigeminal ganglia to all around the forming teeth, the presence of axons in the dental mesenchyme was detected in less than 2.5% of samples after two weeks, demonstrating a specific impairment of their entering the dental mesenchyme. In clinical context, immunosuppressive therapy using cyclosporin A was found to accelerate the innervation of transplanted tissues. Indeed, when cultured cell re-associations and trigeminal ganglia were co-implanted in cyclosporin A-treated ICR mice, nerve fibers were detected in the dental pulp, even reaching odontoblasts after one week. However, cyclosporin A shows multiple effects, including direct ones on nerve growth. To test whether there may be a direct functional relationship between immunomodulation and innervation, cell re-associations and trigeminal ganglia were co-implanted in immunocompromised Nude mice. In these conditions as well, the innervation of the dental mesenchyme was observed already after one week of implantation, but axons reached the odontoblast layer after two weeks only. This study demonstrated that immunodepression per se does stimulate the innervation of the dental mesenchyme
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