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See detailEmission of alarm pheromone in aphids: A non-contagious phenomenon
Verheggen, François ULg; Mescher, M. C.; Haubruge, Eric ULg et al

in Journal of Chemical Ecology (2008), 34(9), 1146-1148

In response to attack by natural enemies, most aphid species release an alarm pheromone that causes nearby conspecifics to cease feeding and disperse. The primary component of the alarm pheromone of most ... [more ▼]

In response to attack by natural enemies, most aphid species release an alarm pheromone that causes nearby conspecifics to cease feeding and disperse. The primary component of the alarm pheromone of most species studied is (E)-beta-farnesene. We recently demonstrated that the production and accumulation of (E)-beta-farnesene during development by juvenile aphids is stimulated by exposure to odor cues, most likely by (E)-beta-farnesene emitted by other colony members. Here, we tested whether the release of (E)-beta-farnesene can be triggered by exposure to the alarm pheromone of other individuals, thereby amplifying the signal. Such contagious emission might be adaptive under some conditions because the amount of (E)-beta-farnesene released by a single aphid may not be sufficient to alert an appropriate number of individuals of the colony to the presence of a potential threat. By using a push-pull headspace collection system, we quantified (E)-beta-farnesene released from Acyrthosiphon pisum aphids exposed to conspecific alarm signals. Typical avoidance behavior was observed following exposure to (E)-beta-farnesene (i.e., aphids ceased feeding and dropped from host-plant); however, no increase in alarm pheromone amount was detected, suggesting that contagious release of (E)-beta-farnesene does not occur. [less ▲]

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See detailDiscrimination of parasitized aphids by a hoverfly predator: effects on larval performance, foraging, and oviposition behavior
Almohamad, Raki; Verheggen, François ULg; Francis, Frédéric ULg et al

in Entomologia Experimentalis et Applicata (2008), 128(1), 73-80

The choice of oviposition site by female aphidophagous predators is crucial for offspring performance, especially in hoverflies whose newly hatched larvae are unable to move over large distance. Predator ... [more ▼]

The choice of oviposition site by female aphidophagous predators is crucial for offspring performance, especially in hoverflies whose newly hatched larvae are unable to move over large distance. Predator and parasitoid interactions within the aphidophagous guild are likely to be very important in influencing the choices made by predatory hoverfly females. In the present study, the foraging and oviposition behavior of the aphidophagous hoverfly Episyrphus balteatus DeGeer (Diptera: Syrphidae) was investigated with respect to the parasitized state of its aphid prey, Acyrthosiphon pisum Harris (Homoptera: Aphididae), that were parasitized by Aphidius ervi Haliday (Hymenoptera: Aphidiidae). We also recorded the number of eggs laid by hoverfly females when subjected to parasitized aphids. Furthermore, we studied the influence of being fed with parasitized aphids on hoverfly larval performance. Hoverfly females did not exhibit any preference for plants infested with unparasitized or aphids parasitized for 7 days. On the other hand, plants infested with mummies or exuvia were less attractive for E. balteatus. These results were correlated with (i) the number of eggs laid by E. balteatus females and (ii) larval performance. Thus, our results demonstrate that E. balteatus behavior is affected by parasitoid presence through their exploitation of aphid colonies. Indeed, hoverfly predators select their prey according to the developmental state of the parasitoid larvae. [less ▲]

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See detailWhat makes Episyrphus balteatus (Diptera: Syrphidae) oviposit on aphid infested tomato plants?
Verheggen, François ULg; Capella, Quentin ULg; Wathelet, Jean-Paul ULg et al

in Communications in Agricultural and Applied Biological Sciences (2008), 73(3), 371-81

Under attack by insect pests, many plant species change their volatile chemical emissions to attract natural enemies. Most of the tomato (Lycopersicon sp., Solanaceae) varieties are subjected to ... [more ▼]

Under attack by insect pests, many plant species change their volatile chemical emissions to attract natural enemies. Most of the tomato (Lycopersicon sp., Solanaceae) varieties are subjected to infestation by molluscs and insects, including the generalist aphid Myzus persicae Sulzer (Homoptera, Aphididae). Episyrphus balteatus De Geer (Diptera: Syrphidae) is a generalist aphid predator that was here observed to lay eggs on M. persicae infested tomato but not on non-infested plants. In order to identify the volatile chemicals that guide the foraging and oviposition behaviour of E. balteatus, we collected and identified volatiles released in the headspace of both aphid infested and uninfested tomato plants by SPME-GC-MS. The identified chemicals were subsequently tested by electroantennography (EAG) on E. balteatus. Monoterpenes and sesquiterpenes were identified, the main volatile chemicals being beta-phellandrene, 2-carene, alpha-phellandrene, 3-carene and o-pinene. Electrical depolarizations were observed for each tested monoterpene, with optimal responses ranging from -0.2 to -0.8 mV. Episyrphus balteatus antennae showed dose-response relationships towards all the active chemicals. (E)-beta-farnesene, the main component of the aphid alarm pheromone, was the only active sesquiterpene, and is presumed to act as an oviposition stimulus for E. balteotus. [less ▲]

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See detailNouvelles estimations des effectifs de l’Agrion de Mercure (Coenagrion mercuriale) dans la plaine du Biran (Commune de Beauraing, Belgique) avec une analyse des principaux facteurs écologiques expliquant son abondance.
Couvreur, Jean-Marc; Dufrêne, Marc ULg; Goffart, Philippe et al

in Bulletin de la Société Royale Belge d'Entomologie = Bulletin van de Koninklijke Belgische Vereniging voor Entomologie (2008), 144

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See detailAnalysis of lateral mobility of Ardenne rivers during the last centuries using iron slag
Houbrechts, Geoffrey ULg; Snijders, Jean-Philippe; Petit, François ULg

Poster (2008)

In the Ardenne region, old maps of different periods indicate that the layout of major rivers has been relatively stable since the end of the 18th century. However, given the scale of the different ... [more ▼]

In the Ardenne region, old maps of different periods indicate that the layout of major rivers has been relatively stable since the end of the 18th century. However, given the scale of the different documents and the relative inaccuracy of their georeferencing, it is not possible to precisely measure the rivers’ lateral erosion or to study the dynamic of small rivers. Moreover, maps older than the 18th century are not precise enough to permit this type of approach. Quantities of slag elements are present in the Ardenne rivers. These waste products come from hundreds of ironworks (blast furnaces and bloomeries) built close to different-sized rivers between the 14th and the 19th centuries. Slag was piled onto the floodplains and frequently thrown out directly into the rivers. For centuries, these slag elements were carried away during floods and were spread out along rivers. Given their properties, slag elements can be easily identified in sediments. When the slag elements are present in fine sediments at the point of contact with the gravel sheet, it means that the river has moved laterally since the inception of the iron industry, swept away older sediments and deposited more recent sediments contaminated by the slag. From historical studies, we precisely dated the periods of ironwork activity in several valleys. We also analysed the vertical concentrations of slag elements in several borings carried out along perpendicular cross sections. These data allowed us to estimate the lateral erosion velocity of some channels over several centuries. Moreover, we reconstructed the topography of several alluvial plains at the time ironworks were established and we evaluated sedimentation rates. [less ▲]

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See detailEen nieuwe verspreidingsatlas van de loopkevers en zandloopkevers (Carabidae) in België.
Desender, Konjev; Dekoninck, W.; Maes, Dirk et al

Book published by Instituut voor Natuur- en Bosonderzooek (2008)

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See detailReport from Belgium
Gsir, Sonia ULg

in Doomernik, Jeroen; Jandl, Michael (Eds.) Modes of Migration Regulation and Control in Europe. (2008)

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See detailArrêt « Doulamis » : concurrence et publicités relatives aux soins de santé
Sibony, Anne-Lise ULg

in Journal des Tribunaux Droit Européen (2008), 6

A national legislation prohibiting advertisments for healthcare services is not contrary to European competition law.

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See detailPapillons de jour de Wallonie (1985-2007)
Fichefet, Violaine; Barbier, Yvan; Baugnée, Jean-Yves et al

Book published by Service Public de Wallonie, Direction Générale de l'Agriculture, des Ressources Naturelles et de l'Environnement - Service Public de Wallonie, Direction Générale de l'Agriculture, des Ressources Naturelles et de l'Environnement (2008)

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See detailLes troubles de la déglutition du sujet âgé : un problème trop souvent sous-estimé
Allepaerts, Sophie ULg; Delcourt, Sandrine ULg; Petermans, Jean ULg

in Revue Médicale de Liège (2008), 63(12), 715-21

Swallowing disorders are frequently observed in the elderly and often accompany an organic pathology. Such disorders may quickly constitute a threat for life: inhalation syndrome, pulmonary infection ... [more ▼]

Swallowing disorders are frequently observed in the elderly and often accompany an organic pathology. Such disorders may quickly constitute a threat for life: inhalation syndrome, pulmonary infection, undernutrition, dehydration. Diagnosing swallowing disorders is difficult and relies on anamnesis, clinical examination combined with paraclinical investigations. However, there is little place for medicinal or surgical treatment, their management being integral and multidisciplinary. [less ▲]

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See detailDevelopment and validating procedure of a formula to calculate a minimum separation distance from piggeries and poultry facilities to sensitive receptors
Nicolas, Jacques ULg; Delva, Julien ULg; Cobut, Pierre et al

in Atmospheric Environment (2008), 42(30), 7087-7095

A specific formula to calculate separation distance from piggeries and poultry facilities to sensitive receptor is developed for Walloon Region, in Belgium. The paper briefly presents the main principles ... [more ▼]

A specific formula to calculate separation distance from piggeries and poultry facilities to sensitive receptor is developed for Walloon Region, in Belgium. The paper briefly presents the main principles of the formula and discusses more deeply the compatibility of the distance approach with odour units, odour rate and percentiles usually applied to assess the odour annoyance zones. A method of validation is presented and tested to adjust the different parameters of the formula to Belgian field reality. A total of 43 farms of which 21 piggeries and 22 poultry facilities are visited and, for each case, the distance calculated by the formula is compared to the one deduced from odour annoyance criterion (10 ou m-3 at 98th percentile). Validation work results in discussing the sensibility of different factors of the formula and especially in adjusting a fitting factor to match the absolute distances to real field annoyance impression. Conclusions show that both approaches - separation distance formula and percentile evaluation - are coherent. The validation method allows parameter adjustment but should need further refinements to examine separately piggeries and poultry facilities. [less ▲]

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See detailLes soins de santé primaires: maintenant plus que jamais
World Health Organization; Porignon, Denis ULg

Book published by WHO (2008)

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See detailVerviers, au fil de l'eau et de la laine : histoire, tourisme et politique
Drouguet, Noémie ULg

in La Lettre de l'OCIM (2008), 119

With the example of the city of Verviers, the author focusses on the conception and the role of the interpretation centers in Belgium. She draws up the balance sheet of the experience started in 2004 and ... [more ▼]

With the example of the city of Verviers, the author focusses on the conception and the role of the interpretation centers in Belgium. She draws up the balance sheet of the experience started in 2004 and shows the lack of appeal of theses places, marked by fixed displays and the difficulties in reaching the public and building up a loyal audience. [less ▲]

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See detailThéorie et pratique (Série Actes, 1)
Dewalque, Arnaud ULg; Seron, Denis ULg

in Bulletin d'Analyse Phénoménologique (2008), IV(3),

Ce numéro rassemble des textes issus de travaux menés dans le cadre d’un séminaire doctoral sur le thème « Théorie et pratique », qui s’est tenu à l’Université de Liège durant une semaine complète, du 21 ... [more ▼]

Ce numéro rassemble des textes issus de travaux menés dans le cadre d’un séminaire doctoral sur le thème « Théorie et pratique », qui s’est tenu à l’Université de Liège durant une semaine complète, du 21 au 25 mai 2007. Le but du séminaire était d’évaluer la part prise par des philosophes de style phénoménologique (au sens le plus large) dans certains débats, centraux dans la philosophie du XXe siècle, qui se rattachent directement à la distinc- tion entre théorie et pratique. Parmi ces débats, il faut compter ceux soulevés et animés par les pragmatistes autour de la définition de la vérité en termes de « conséquences pratiques », par certains néokantiens et par Brentano et Husserl autour du rapport entre logique et éthique, par Husserl sur la question du psychologisme, par des sociologues phénoménologues comme Schütz autour de la « coupure épistémologique », mais aussi les controverses des intellectuels français d’après-guerre, qui, aujourd’hui encore, déterminent en profondeur le devenir de la philosophie française. Ces problèmes sont au centre du présent recueil. [less ▲]

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See detailEntwicklung der Kritizismus in der deutschen Philosophie des 19.-20. Jahrhunderts
Dewalque, Arnaud ULg

E-print/Working paper (2008)

Tableau synoptique du mouvement criticiste et des différentes écoles qui le composent.

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See detailBibliographische Übersicht der deutschsprachigen Logik-Handbücher 1830-1930 in chronologischer Reihenfolge zugeordnet
Dewalque, Arnaud ULg

E-print/Working paper (2008)

Les manuels de logique traditionnelle qui ont vu le jour au XIXe siècle dans la philosophie de langue allemande ont été le lieu de véritables réflexions philosophiques sur des questions absolument ... [more ▼]

Les manuels de logique traditionnelle qui ont vu le jour au XIXe siècle dans la philosophie de langue allemande ont été le lieu de véritables réflexions philosophiques sur des questions absolument fondamentales : la question du statut des propositions et des formations logiques en général, la question du sens, celle de la vérité, celle des positions d’existence, etc. Historiquement parlant, ces manuels constituent, à côté de l’abondante littérature engendrée par la psychologie naissante, l’une des sources majeures de la philosophie contemporaine. Mais ils sont aussi le lieu où s’est développé et où a été reformulé de façon privilégiée le programme critique kantien de fondation des sciences et de la connaissance en général. Pour toutes ces raisons, l’énorme masse des manuels de logique apparus au XIXe siècle constitue un terrain d’investigation particulièrement digne d’intérêt, avant tout sur le plan de l’histoire de la philosophie. Mais c’est aussi un terrain d’investigation difficile à embrasser du regard. Créée afin de remédier à cette difficulté, cette liste bibliographique entend offrir un aperçu – nécessairement partiel – de la production philosophique consacrée aux questions de logique entre 1830 et 1930 dans l’espace germanophone [less ▲]

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See detailLe juge et le raisonnement économique en droit de la concurrence
Sibony, Anne-Lise ULg

Book published by L.G.D.J. (2008)

Economic reasoning is a distinctive feature of competition law. At first sight, it may appear as foreign to judges. A closer analysis, however, shows that there is no conflict of logic between economic ... [more ▼]

Economic reasoning is a distinctive feature of competition law. At first sight, it may appear as foreign to judges. A closer analysis, however, shows that there is no conflict of logic between economic and judicial reasoning. Some points of convergence between these modes of reasoning are underlined. In addition, it is submitted that obstacles to judicial acknowledgement of economic reasoning are purely relative. The proposed analysis then proceeds to investigate how economic reasoning may be incorporated into judicial methods. It is shown that this is achieved by way of ordinary mechanisms. Indeed judges may use economic analysis to determine the relevant facts and legal tests. It follows that judicial control over economic reasoning – including that of competition authorities – can be explained by a very general theory of judicial review, according to which the depth of judicial control over grounds of fact and law depends on the dynamics of litigants’ contentions. [less ▲]

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See detailDust in the Wind and Public Health: Example from Mauritania.
Ozer, Pierre ULg

in Ozer, André; Swinne, Danièle (Eds.) Desertification: Migration, Health, Remediation and Local Governance. (2008)

The Sahara largely contributes to the global injection of mineral dust into the northern hemisphere. Since the onset of the drought in the Sahel and the environmental degradation in the arid and semi-arid ... [more ▼]

The Sahara largely contributes to the global injection of mineral dust into the northern hemisphere. Since the onset of the drought in the Sahel and the environmental degradation in the arid and semi-arid belts surrounding the Sahara, dust storms frequency and intensity has dramatically increased. It is now irrefutable that air pollution caused by large amounts of respiratory particulates or Particulate Matter less than 10 µm in aerodynamic diameter (PM10) has numerous undesired consequences on human health. Air quality degradation far away from the African continent in the US and in Europe caused by high concentration of African dust is seen as a major health threat although most of these countries are very distant from the Sahara. Surprisingly, no estimates of PM10 levels near the Saharan dust source are available. Based on horizontal visibility observations which are reduced by the presence of dust in the atmosphere, PM10 levels are estimated at the station of Nouakchott, Mauritania by using relations found in the literature. It appears that excessive concentrations of particles are very important both in magnitude and frequency as the 24-hour PM10 thresholds established by the US EPA National Ambient Air Quality Standards and the EU Limits Values for Air Quality were systematically exceeded. The average yearly concentration is far above air quality standards. These very high particulate levels are likely to represent an important public health threat and should be considered as a major environmental risk. We present here a first comparison between monthly respiratory diseases data and PM10 concentrations due to dust storms. [less ▲]

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