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See detailPlanning under uncertainty, ensembles of disturbance trees and kernelized discrete action spaces
Defourny, Boris ULg; Ernst, Damien ULg; Wehenkel, Louis ULg

in Proceedings of the IEEE International Symposium on Adaptive Dynamic Programming and Reinforcement Learning (ADPRL-09) (2009)

Optimizing decisions on an ensemble of incomplete disturbance trees and aggregating their first stage decisions has been shown as a promising approach to (model-based) planning under uncertainty in large ... [more ▼]

Optimizing decisions on an ensemble of incomplete disturbance trees and aggregating their first stage decisions has been shown as a promising approach to (model-based) planning under uncertainty in large continuous action spaces and in small discrete ones. The present paper extends this approach and deals with large but highly structured action spaces, through a kernel-based aggregation scheme. The technique is applied to a test problem with a discrete action space of 6561 elements adapted from the NIPS 2005 SensorNetwork benchmark. [less ▲]

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See detailPlans expérimentaux
Boulanger, Bruno ULg; Govaerts, B.; Le Boulengé, E. et al

Learning material (2010)

Vidéos du cours intitulé "Plans expérimentaux"

Detailed reference viewed: 84 (14 ULg)
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See detailLes plans simples de gestion pour les ressources des communautés
Dubiez, Emilien; Vermeulen, Cédric ULg; Larzillière, Adélaïde et al

in Louppe, Dominique; Larzillière, Adélaïde (Eds.) Quand la ville mange la forêt : les défis du bois-énergie en Afrique centrale (2013)

Detailed reference viewed: 29 (7 ULg)
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See detailThe plant alkaloid usambarensine intercalates into DNA and induces apoptosis in human HL60 leukemia cells
Dassonneville, L.; Wattez, N.; Mahieu, C. et al

in Anticancer Research (1999), 19(6B), 5245-5250

Detailed reference viewed: 26 (3 ULg)
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See detailPlant and their soil environment
Delaplace, Pierre ULg

Conference (2009)

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See detailPlant communities and species richness of the calcareous grasslands in southeast Belgium
Piqueray, Julien ULg; Bisteau, Emmanuelle ULg; Bottin, Gaëtan et al

in Belgian Journal of Botany (2007), 140(2), 157-173

Calcareous grasslands are biodiversity hotspots in Western Europe. In Belgium, a number of phytosociological surveys have been realized in these habitats, but none covers the whole range of calcareous ... [more ▼]

Calcareous grasslands are biodiversity hotspots in Western Europe. In Belgium, a number of phytosociological surveys have been realized in these habitats, but none covers the whole range of calcareous grasslands at the regional scale. The aim of this study was (i) to provide a synthesis of the floristic variation of calcareous grasslands of the Calestienne natural region using a uniform methodology; (ii) to relate floristic variation to environmental variables, and (iii) to characterize the specific diversity of the different grassland communities that occur in the study region. Seven different communities were identified with the TWINSPAN method. The originality of the grasslands on calcareous and calcareo-siliceous rocks was statistically confirmed. Significant differences for environmental variables were identified among the seven communities by a MANOVA. Main differences between communities were related to xericity and pH, although a north-south gradient was also identified. More xeric grasslands were located in the southern part of the study region while northern part was occupied by more mesophilous grasslands. Multiple regressions were used to describe the influence of the environmental conditions on plant species richness. The most mesophilous grasslands appeared to be the most species-rich while soil acidity negatively affected species richness. [less ▲]

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See detailPlant defense reactions stimulated following perception of Bacillus lipopeptides
Ongena, Marc ULg; Henry, G.; Jourdan, E. et al

Conference (2009)

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See detailPlant defense stimulation by natural isolates of Bacillus depends on efficient surfactin production
Cawoy, Hélène ULg; Mariutto, Martin; Henry, Guillaume et al

in Molecular Plant-Microbe Interactions [=MPMI] (2013)

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See detailPlant ecological niche distribution along heavy metal gradients
Boisson, Sylvain ULg; Monty, Arnaud ULg; Seleck, Maxime ULg et al

Conference (2013, June 26)

Why species do not occur everywhere? The concept of ecological niche is central to understand relationships among biotic/abiotic factors and species distribution. Gradients of environmental stress ... [more ▼]

Why species do not occur everywhere? The concept of ecological niche is central to understand relationships among biotic/abiotic factors and species distribution. Gradients of environmental stress associated to interspecific interactions generate testable patterns of specie’s response curves. Distribution of response curves have been seldom tested along toxicity gradient, in contrast to resource gradients. On Katangan copper hills (south R.D.C.), natural copper and cobalt concentrations span a large range: 2 - 1000 mg kg-1 for cobalt and 30 - 10 000 mg kg-1 for copper. In this study, we evaluate three hypotheses related to niche distributions and shapes along metal toxic gradients: (1) Species optima are uniformly distributed over copper-cobalt gradient. (2) Realized niche width varies in relation to the niche optimum along copper and cobalt gradient. (3) Absolute values of skewness coefficient are higher when plant species optima are in the extremes of cobalt gradient with a niche tails toward mesic conditions. Realized niches of 80 taxa were modeled with general additive models (GAM) using presence/absence data in 172 1m² plots. Niche optima, niche widths and skewness coefficients were estimated from species response curves. The three hypotheses were globally validated. Three groups of species were distinguished according to their optima position along metal gradient with packed optima on intermediate concentrations suggesting higher interspecific competition in low metal concentrations. Niche width increased with metal concentrations. Highest metal tolerant plant species had broader niches. Skewness coefficient was inversely related to niche optima positions. Our study demonstrates that species distribution pattern on toxicity gradient presents similarities with resource gradient. Broad realized amplitude of species adapted to high levels of copper cobalt concentrations suggests that fundamental niche of specialist metallophytes may be larger than expected. This should be further tested in controlled conditions in association to competition tests. [less ▲]

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See detailPlant greening - Biogenesis of photosynthetic apparatus in bean leaves irradiated shortly after germination
Schoefs, B.; Bertrand, M.; Franck, Fabrice ULg

in Photosynthetica (1992), 27(4), 497-504

Formation of the photosynthetic apparatus in dark-grown 2-day-old bean (Phaseolus vulgaris L.) leaves was studied. The photosystem 2 (PS 2) reaction centres started functioning 1 h after the beginning of ... [more ▼]

Formation of the photosynthetic apparatus in dark-grown 2-day-old bean (Phaseolus vulgaris L.) leaves was studied. The photosystem 2 (PS 2) reaction centres started functioning 1 h after the beginning of irradiation. Electron transport between the two photosystems started after 4 h of irradiation. The PS 2 units were able to transfer the excitation energy to each other after 10 h of greening. The photosynthetic activity appeared a long time before the typical 77 K fluorescence bands of green leaves appeared. [less ▲]

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See detailPlant growth promotion of tomato under field conditions in Burundi
Cawoy, Hélène ULg; Nihorimbere, Venant; Kakana, Pascal et al

Poster (2009, April 02)

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See detailPlant growth- promoting rhizobacteria emit volatiles compounds with biostimulation activity in dicot and monocot plant species.
du Jardin, Patrick ULg; Delaplace, Pierre ULg; Varin, Sébastien et al

in Perata, Pierdomenico; Brown, Patrick; Ponchet, Michel (Eds.) Abstracts Book for Oral and Poster Presentations of the 1st World Congress on the use of Biostimulants in Agriculture (2012, November)

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See detailPlant leaf roughness analysis by texture classification with generalized Fourier descriptors in a dimensionality reduction context
Journaux, L.; Simon, J.-C.; Destain, Marie-France ULg et al

in Precision Agriculture (2011), 12(3), 345-360

In the context of plant leaf roughness analysis for precision spraying, this study explores the capability and the performance of some combinations of pattern recognition and computer vision techniques to ... [more ▼]

In the context of plant leaf roughness analysis for precision spraying, this study explores the capability and the performance of some combinations of pattern recognition and computer vision techniques to extract the roughness feature. The techniques merge feature extraction, linear and nonlinear dimensionality reduction techniques, and several kinds of methods of classification. The performance of the methods is evaluated and compared in terms of the error of classification. The results for the characterization of leaf roughness by generalized Fourier descriptors for feature extraction, kernel-based methods such as support vector machines for classification and kernel discriminant analysis for dimensionality reduction were encouraging. These results pave the way to a better understanding of the adhesion mechanisms of droplets on leaves that will help to reduce and improve the application of phytosanitary products and lead to possible modifications of sprayer configurations. [less ▲]

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See detailThe plant Leclercqia (Lycopsida) in Gondwana: implications for reconstructing Middle Devonian palaeogeography
Meyer-Berthaud, B.; Fairon-Demaret, Muriel ULg; Steemans, Philippe ULg et al

in Geological Magazine (2003), 140(2), 119-130

Abundant and well-preserved material of the ligulate lycopsid genus Leclercqia is reported from a new Middle Devonian locality in northeastern Queensland (Australia). The plants occur in a chert horizon ... [more ▼]

Abundant and well-preserved material of the ligulate lycopsid genus Leclercqia is reported from a new Middle Devonian locality in northeastern Queensland (Australia). The plants occur in a chert horizon in the Storm Hill Sandstone of the Dosey-Craigie Platform. Lithological data and conodont analyses combined with information from in situ spores provide an age for the plant levels ranging from Eifelian, possibly Middle Eifelian, to Early Givetian. Plant taxonomic identification is based on vegetative and fertile stems that display both external morphology and anatomy. This material represents the best documented occurrence of Leclercqia outside Laurussia and possibly the earliest in Gondwana; it provides evidence that colonization of Gondwana by the species L. complexa was contemporaneous to that of Siberia and Kazakhstan. Analysis of the distribution patterns of L. complexa suggests that it was adapted to a wide range of environments, but within certain limits which we hypothesize to be those of a climatic belt. Such considerations support previous studies using other biological data, such as faunas and palynomorphs, for reconstructing Devonian palaeogeography. They favour a close proximity of Laurussia and Gondwana rather than the occurrence of a wide ocean separating the two palaeocontinents in Middle Devonian times. [less ▲]

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