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See detailDensité et écologie des chimpanzés (Pan troglodytes schweinfurthii) dans le Parc National de la Kibira, Burundi
Hakizimana, Dismas ULg

Doctoral thesis (2014)

Les forêts tropicales africaines et les communautés de primates qu'elles abritent sont sérieusement menacées par l'accélération des taux de conversion et de dégradation des forêts ainsi que par les ... [more ▼]

Les forêts tropicales africaines et les communautés de primates qu'elles abritent sont sérieusement menacées par l'accélération des taux de conversion et de dégradation des forêts ainsi que par les activités de braconnage. L'impact de ces menaces est si grand que certaines communautés de primates ont complètement disparu avant d’avoir été reconnues, encore moins étudiées. Des données référentielles sont toujours nécessaires pour comprendre les variations spatio-temporelles des primates. Les estimations de la densité ou d'abondance des populations sont des outils de première importance lors de la détermination des priorités de conservation et de la mise en place d’un plan de gestion des populations de primate. Comme dans les écosystèmes forestiers, la répartition et l’abondance des différentes espèces d’arbres influencent profondément les communautés animales qui y vivent, nous avons d’abord cherché à déterminer la densité et la structure des espèces d’arbres de la forêt de Kibira. Dans 256 plots couvrant une superficie de 32,15 ha, un total de 6.504 arbres répartis en 70 espèces, 67 genres et 37 familles ont été enregistrés. La densité était de 202 tiges par hectare, avec une surface basale de 21,05 m² par hectare. Au total, six espèces de primates diurnes ont été enregistrées dont une espèce anthropoïde (Pan troglodytes schweinfurthii), quatre cercopithecinae (Cercopithecus mitis, Cercopithecus mona denti, Cercopithecus lhoesti et Lophocebus albigena) et une colobinae (Colobus angolensis). Seule la densité et l’effectif total de la population des chimpanzés sont connus, tandis que pour le reste des espèces, seul l’indice d’abondance kilométrique a été calculé. Cette recherche a accordé une attention particulière à l’espèce emblématique du Parc National de la Kibira, le chimpanzé d’Afrique de l’est, Pan troglodytes schweinfurthii. Afin de mieux protéger cette sous-espèce en danger d’extinction, nous avons mené des investigations sur les sites de nidification pour identifier les espèces et les caractéristiques des arbres sur lesquelles les chimpanzés comptent pour la construction des nids. Les résultats ont montré que les chimpanzés sélectionnent certaines espèces d’arbres lors de la construction des nids. Le secteur Mabayi, situé au nord du parc, est le plus riche en espèces de primates; il abrite cinq espèces sur les six enregistrées, et deux espèces: Cercopithecus lhoesti (menacée) et Colobus angolensis ne se retrouvent qu’à Mabayi uniquement. Cette partie du parc constitue une clé pour la diversité et devrait par conséquent bénéficier d’une attention particulière en matière de protection et conservation. [less ▲]

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See detailDensité Minérale Osseuse et risque fracturaire : une relation prédictive?
Bruyère, Olivier ULg

Conference (2007, October 13)

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See detailDensité osseuse fémorale et carence vitaminique D dans une population de femmes âgées
DEROISY; Pirenne, H; FREDERICK, Isabelle ULg et al

in Archives of Public Health (1996), 53(S1), 37

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See detailDensité osseuse fémorale et carence vitaminique D dans une population de femmes âgées
DEROISY; Pirenne, H; Frederick, I et al

in Revue du Rhumatisme (1995), 10

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See detailDensité spatiale des étoiles Ap
Renson, Pierre ULg

in Publications of the Astronomical Society of Japan (1972), 24

Abstract image available at: http://adsabs.harvard.edu/abs/1972PASJ...24..149R

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See detailDensité, morphologie urbaine et qualité de vie. Une approche par le projet
Occhiuto, Rita ULg; Goossens, Marc ULg; Fisher, Axel ULg et al

Report (2013)

La recherche "Densification des tissus urbanisés en Wallonie: forme, acceptabilité et modalités pour accompagner la mutation des tissus bâtis" s'articule en plusieurs volets thématiques, parmi lesquels ... [more ▼]

La recherche "Densification des tissus urbanisés en Wallonie: forme, acceptabilité et modalités pour accompagner la mutation des tissus bâtis" s'articule en plusieurs volets thématiques, parmi lesquels figure le volet "formes urbaines, modes d'habitat". Ce dernier volet est abordé selon deux approches parallèles et complémentaires qui se valident mutuellement: la première dite "par le projet" (approche qualitative et opérationnelle) et la seconde par analyse statistique et cartographique (approche descriptive et quantitative). Ces deux approches partagent l'objet d'étude - les tissus urbains - mais diffèrent sur la méthodologie. Nous présentons ici les premiers résultats de l'approche dite "par le projet", suivant une structure en quatre parties principales. La première partie fait le point sur la démarche, utile pour repréciser les objectifs, méthodes et limites de l'approche. La deuxième partie propose une définition des objets d'étude et des principaux termes utilisés, en relation à la problématique de recherche. La troisième partie développe la méthode à partir du cas d'étude spécifique de Ath, mis en perspective par rapport aux autres cas d'études traités et présentés dans le rapport final de recherche 2012-2013 (principalement quatre "petites villes" sélectionnées: Ath, Marche-en-Famenne, Arlon et Saint Vith). En conclusion, il est fait état des premièrs résultats de la recherche et des pistes pour la suite des travaux. [less ▲]

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See detailDensitometric Determination of Salicin in Willow Stem Bark
Poukens-Renwart, Pascale; Tits, Monique ULg; Angenot, Luc ULg

in Journal of Planar Chromatography (1993), 6(november-december), 434-437

Most of the salicin present in willow stem bark occurs as labile glycosides (e.g. salicin, salicortin, 2-O'-acetylsalicortin, 3-O'-acetylsalicortin, tremulacin and fragilin). On alkaline hydrolysis, these ... [more ▼]

Most of the salicin present in willow stem bark occurs as labile glycosides (e.g. salicin, salicortin, 2-O'-acetylsalicortin, 3-O'-acetylsalicortin, tremulacin and fragilin). On alkaline hydrolysis, these acylated derivatives decompose to salicin; in this way, the total amount of salicin can be determined. A HPTLC method has been developed for the quantitative determination of salicin in stem bark before and after alkaline hydrolysis. The mobile phase used for the separation is a modification of one described in the literature. a double or triple migration is necessary to separate salicin from other components of the extract. The results have been compared with those obtained after bidimensional chromatography using two phases described for the quantitative evaluation of salicin. to check that separation was complete, the spectrum of salicin obtained from willow extracts was superimposed on that of a salicin standard.Quantification was performed at lambda = 270nm, the wavelenght of maximum absorption in the IV spectrum of salicin. [less ▲]

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See detailDensitometric Evaluation of fraxin in leaves of Fraxinus excelsior
Poukens-Renwart, Pascale; Tits, Monique ULg; Wauters, Jean-Noël ULg et al

in Journal de Pharmacie de Belgique (1992), 47(3), 241

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See detailDensitometric evaluation of fraxin in leaves of Fraxinus excelsior
Poukens-Renwart, Pascale; Tits, Monique ULg; Wauters, Jean-Noël ULg et al

Poster (1992, May)

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See detailDensitometric Evaluation of Gentiopicroside in the Roots of Gentiana lutea L.
Bodart, Patricia; Poukens-Renwart, Pascale; Wauters, Jean-Noël ULg et al

in Journal of Planar Chromatography- Modern TLC (1996), 9(March/April), 143-145

As no satisfactory method existed for the separation of gentiopicroside from other components of gentian roots, we have decided to undertake some experiments.In this communication, we report the use of a ... [more ▼]

As no satisfactory method existed for the separation of gentiopicroside from other components of gentian roots, we have decided to undertake some experiments.In this communication, we report the use of a novel mobile phase and a different detection system. Our HPTLC method is a fast and reliable procedure which may be used for quantification of gentiopicroside in roots and extracts of Gentiana lutea, whether for routine analysis or for studying stability. The TLC method is also compared with an HPLC method. [less ▲]

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See detailDensitometric Evaluation of Spiraeoside after Derivatization in Flowers of Filipendula Ulmaria (L.) Maxim
Poukens-Renwart, P.; Tits, Monique ULg; Wauters, Jean-Noël ULg et al

in Journal of Pharmaceutical & Biomedical Analysis (1992), 10(10-12, Oct-Dec), 1085-8

Spiraeoside (quercetin-4'-glucoside) is the major and most caharacteristic flavonoid of Filipendula ulmaria flowers and is not found in the leaves and stems. This paper describes a quantification of ... [more ▼]

Spiraeoside (quercetin-4'-glucoside) is the major and most caharacteristic flavonoid of Filipendula ulmaria flowers and is not found in the leaves and stems. This paper describes a quantification of spiraeoside by HPTLC densitometry after derivatization with diphenylboric acid -2-aminoester. The fluorescence of this flavonoid was measured at 330 nm. the spiraeoside content in batches of Filipendula ulmaria flowers ranged from 3 to 4.3 %. It is of note that these results are similar to those published elsewhere after HPLC analysis of other batches. [less ▲]

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See detailDensitometric evaluation of spiraeoside after derivatization in flowers of Filipendula ulmaria (L.) Maxim.
Poukens-Renwart, Pascale; Tits, Monique ULg; Wauters, Jean-Noël ULg et al

Poster (1992, September)

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See detailDensitometric evaluation of spiraeoside in Filipendula ulmaria flowers after derivatization
Poukens-Renwart, Pascale; Tits, Monique ULg; Wauters, Jean-Noël ULg et al

Poster (1992)

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See detailA Densitometric Method for the Determination of Three Clinically Important Monosaccharides in Urine
Poukens-Renwart, Pascale; Angenot, Luc ULg

in Journal of Planar Chromatography (1991), 4(January/February), 77-79

A quantitative, densitometric, thin layer chromatographic method has been developed for the determination of three clinically important monosaccharides in ureine, after desalting.The analysis of these ... [more ▼]

A quantitative, densitometric, thin layer chromatographic method has been developed for the determination of three clinically important monosaccharides in ureine, after desalting.The analysis of these monosaccharides in urine allows to observe the potential changes induced by antiinflammatories in human small intestine permeability. Xylose, 3-O-methylglucose and rhamnose were estimated quantitatively in urine; arabinose was used as internal standard. The densitometry was performed at a wavelenght of 400 nm after a visualization reaction on HPTLC plates. In all cases, coefficients of variation of the method were less than 2.7%. [less ▲]

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See detailDensity and porosity control of sintered 316L stainless steel parts produced by additive manufacturing
Verlee, Bruno; Dormal, Thierry ULg; Lecomte-Beckers, Jacqueline ULg

in Powder Metallurgy (2012), 55(4), 260-267

Additive manufacturing (AM) techniques offer the possibility to build complex geometries with integrated functionalities. Three-dimensional (3D) printing of metallic powder is probably the only AM ... [more ▼]

Additive manufacturing (AM) techniques offer the possibility to build complex geometries with integrated functionalities. Three-dimensional (3D) printing of metallic powder is probably the only AM technique that can build controlled porosity sintered parts, such as filter elements and fluid permeable components. Many building and sintering parameters can be set to adjust porous properties of the final part. The effects of particle size, paricul shape, sintering temperature and sintering time on the final properties of the sinteres parts have been analysed. Correlations have been established between these properties and process parameters [less ▲]

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See detailDensity estimates and nesting-site selection in chimpanzees of the Nimba Mountains, Côte d'Ivoire and Guinea
Granier, Nicolas ULg; Hambuckers, Alain ULg; Matsuzawa, Tetsuro et al

in American Journal of Primatology (2014)

We investigated nesting behavior of non habituated chimpanzees populating the Nimba Mountains to document their abundance and their criterions of nesting-site selection. During a 19-month study we walked ... [more ▼]

We investigated nesting behavior of non habituated chimpanzees populating the Nimba Mountains to document their abundance and their criterions of nesting-site selection. During a 19-month study we walked 80 km of transects and recces each month, and recorded 764 nests (mean group size = 2.23 nests) along with characteristics of vegetation structure and composition, topography and seasonality. Population density estimated with two nest count methods ranged between 0.14 and 0.65 chimpanzee/km2. These values are lower than previous estimates, emphasizing the necessity of protecting remaining wild ape populations. Chimpanzees built nests in 108 tree species out of 437 identified, but 2.3% of total species comprised 52% of nests. Despite they preferred nesting in trees of 25-29 cm DBH and at a mean height of 8.02 m, we recorded an important proportion of terrestrial nests (8.2%) that may reflect a cultural trait of Nimba chimpanzees. A logistic model of nest presence formulated as a function of 12 habitat variables revealed preference for gallery and mountain forests rather than lowland forest, and old-growth forest rather than secondary forests. They nested more frequently in the study area during the dry season (December-April). The highest probability of observing nests was at 770 m altitude, particularly in steep locations (mean ground declivity = 15.54%). Several of the reported nest characteristics combined with the existence of 2 geographically separated clusters of nest, suggest that the study area constitutes the non-overlapping peripheral areas of 2 distinct communities. This nest-based study led us to findings on the behavioral ecology of Nimba chimpanzees, which constitute crucial knowledge to implement efficient and purpose-built conservation. [less ▲]

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See detailDensity Functional Perturbation Theory
Verstraete, Matthieu ULg; Zanolli, Zeila ULg

in Blügel, S.; Helbig, N.; Meden, V. (Eds.) et al Computing Solids: Models, Ab-initio Methods and Supercomputing, Lecture Notes of the 45th Spring School 2014 (2014)

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See detailDensity Functional Perturbation Threory with Spin-Orbit Coupling: the case of Pb
Verstraete, Matthieu ULg; Torrent, M.; Jollet, F. et al

in Physical Review. B : Condensed Matter (2008), 78

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See detailDensity functional theory beyond the linear regime: Validating an adiabatic local density approximation
Helbig, N.; Fuks, J. I.; Casula, M. et al

in Physical Review. A (2011), 83

We present a local density approximation (LDA) for one-dimensional (1D) systems interacting via the soft-Coulomb interaction based on quantum Monte Carlo calculations. Results for the ground-state ... [more ▼]

We present a local density approximation (LDA) for one-dimensional (1D) systems interacting via the soft-Coulomb interaction based on quantum Monte Carlo calculations. Results for the ground-state energies and ionization potentials of finite 1D systems show excellent agreement with exact calculations obtained by exploiting the mapping of an N-electron system in d dimensions onto a single electron in N×d dimensions, properly symmetrized by the Young diagrams. We conclude that 1D LDA is of the same quality as its three-dimensional (3D) counterpart, and we infer conclusions about 3D LDA. The linear and nonlinear time-dependent responses of 1D model systems using LDA, exact exchange, and the exact solution are investigated and show very good agreement in both cases, except for the well-known problem of missing double excitations. Consequently, the 3D LDA is expected to be of good quality beyond the linear response. In addition, the 1D LDA should prove useful in modeling the interaction of atoms with strong laser fields, where this specific 1D model is often used. [less ▲]

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See detailA density functional theory calculation of the electronic properties of several high-spin and low-spin iron(II) pyrazolylborate complexes
Remacle, Françoise ULg; Long, G. J.; Grandjean, Fernande ULg

in Inorganic Chemistry (2008), 47(10), 4005-4014

Density functional theory has been used to study the electronic spin-state properties of low-spin Fe[HB(PZ)(3)](2), lhigh-spin Fe[HB(3-MePZ)(3)](2), high-spin Fe[HB(3,5-Me(2)PZ)(3)](2), and high-spin Fe ... [more ▼]

Density functional theory has been used to study the electronic spin-state properties of low-spin Fe[HB(PZ)(3)](2), lhigh-spin Fe[HB(3-MePZ)(3)](2), high-spin Fe[HB(3,5-Me(2)PZ)(3)](2), and high-spin Fe[HB(3,4,5-Me(3)PZ)(3)](2) complexes that exhibit very different iron(II) electronic spin-sate crossover behaviors with changing temperature and pressure. Excellent agreement is obtained between the experimentally,observed Mossbauer-effect quadrupole splittings and isomer shifts of these complexes and those calculated with the B3LYP functional and various different basis sets for both the high-spin and low-spin states of iron(II). The calculations for Fe[HB(PZ)(3)](2) that use the LANL2DZ, 6-31++G(d,p), and 6-311++G(d,p) basis sets for iron all lead to very similar electric field gradients and thus quadrupole splittings. The initial calculations, which were based upon the known X-ray structures, were followed by structural optimization, an optimization that led to small increases in the Fe-N bond distances. Optimization led to at most trivial changes in the intraligand bond distances and angles. The importance of the 3-methy I-H center dot center dot center dot H-3-methyl nonbonded intramolecular interligand interactions in controlling the minimum Fe-N bond distances and determining the iron(II) spin state both in Fe[HB(3-Mepz)(3)](2) and in the related methyl-substituted complexes has been identified. [less ▲]

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