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See detailEmission of alarm pheromone by non-preyed aphid colonies
Almohamad, Raki; Verheggen, François ULg; Francis, Frédéric ULg et al

in Journal of Applied Entomology (2008), 132(8), 601-604

The sesquiterpene (E)-beta-farnesene (E beta f) is the primary component of the alarm pheromone of most aphid species. It is released in response to physical stress including attack by natural enemies and ... [more ▼]

The sesquiterpene (E)-beta-farnesene (E beta f) is the primary component of the alarm pheromone of most aphid species. It is released in response to physical stress including attack by natural enemies and causes aphids to cease feeding and disperse. E beta f also acts as a kairomonal cue for aphid natural enemies. In this study, we collected the headspace volatiles released by aphid colonies of different sizes. Gas chromatography-mass spectrometry analysis demonstrated the presence of E beta f in the absence of predator attack. A quadratic relationship was found between the released (E)-beta-farnesene amounts and aphid colony size. Behavioural impact of aphid alarm pheromone towards Episyrphus balteatus female oviposition behaviour was also demonstrated in this work. These results highlight the primary role of the small but continuous release of aphid alarm pheromone in mechanisms of decision-making by aphid predators during their foraging and egg-laying behaviour. [less ▲]

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See detailEmission of alarm pheromone in aphids : a contagious phenomenon ?
Verheggen, François ULg; Schwartzberg, Ezra; Haubruge, Eric ULg et al

Conference (2007)

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See detailEmission of alarm pheromone in aphids: A contagious phenomenon?
Verheggen, François ULg; Mescher, Mark; Francis, Frédéric ULg et al

Poster (2008)

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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 detailEmission of CO2 and CH4 to the atmosphere by sediments and open waters in two Tanzanian mangrove forests
Kristensen, Erik; Flindt, Mogens R.; Ulomi, Shadrack et al

in Marine Ecology. Progress Series (2008)

Carbon gas balance was evaluated in an anthropogenically impacted (Mtoni) and a pristine (Ras Dege) mangrove forest in Tanzania. Exchange of carbon dioxide (CO2) was measured for inundated and air-exposed ... [more ▼]

Carbon gas balance was evaluated in an anthropogenically impacted (Mtoni) and a pristine (Ras Dege) mangrove forest in Tanzania. Exchange of carbon dioxide (CO2) was measured for inundated and air-exposed sediments during day and night using in situ and laboratory incubations. In situ methane (CH4) emissions were measured in the dark during air exposure only. Emission of CO2 and CH4 from open waters (e.g. creeks) was estimated from diurnal measurements of CO2, partial pressure (pCO2) and CH4 concentrations. CO2 emission from darkened sediments devoid of biogenic structures was comparable during inundation and air exposure (28 to 115 mmol m–2 d–1) with no differences between mangrove forests. Benthic primary production was low with only occasional net uptake of CO2 by the sediments. Emissions of CH4 from air-exposed sediment were generally 3 orders of magnitude lower than for CO2. Presence of pneumatophores and crab burrows increased low tide emissions several fold. Emissions from open waters were dependent on tidal level and wind speed. Lowest emission occurred during high tide (1 to 6 mmol CO2 m–2 d–1; 10 to 80 μmol CH4 m–2 d–1) and highest during low tide (30 to 80 mmol CO2 m–2 d–1; 100 to 350 μmol CH4 m–2 d–1) when supersaturated runoff from the forest floor and porewater seepage reached the creek water. Based on global average primary production and measured gas emissions, the carbon gas balance of the 2 mangrove forests was estimated. The densely vegetated Ras Dege forest appears to be an efficient sink of greenhouse carbon gases, while extensive clear-cutting at the Mtoni forest apparently has reduced its capacity to absorb CO2, although it is seemingly still a net sink for atmospheric CO2. [less ▲]

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See detailL'émission trading à la Cour d'arbitrage, Commentaire de C.A., 92/2006
Pâques, Michel ULg

in Aménagement - Environnement (2006), 4

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See detailLes Emissions Aurorales Nocturnes de Jupiter
Stiepen, Arnaud ULg

Book published by Editions Universitaires Europeennes (2010)

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See detailLes émissions aurorales nocturnes de Jupiter
Stiepen, Arnaud ULg

Master's dissertation (2010)

Ce travail de fi n d'études est proposé dans le cadre de la deuxième année de Master en Sciences Spatiales du Département d'Astrophysique, Géophysique et Océanographie de l'Université de Liège. Dans un ... [more ▼]

Ce travail de fi n d'études est proposé dans le cadre de la deuxième année de Master en Sciences Spatiales du Département d'Astrophysique, Géophysique et Océanographie de l'Université de Liège. Dans un premier temps, des rappels concernant la planète Jupiter et le phénomène des aurores polaires qui y ont lieu seront effectués. Le but de ce travail est une première analyse d'un ensemble d'images provenant de l'instrument LORRI à bord de la sonde New Horizons de la NASA. Ces deux outils seront dès lors brièvement présentés. La partie suivante sera consacrée au traitement des images reçues de New Horizons et à leur analyse. En n, nous tirerons des conclusions sur le travail exploratoire réalisé et la pertinence de la base de données. [less ▲]

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See detailEmissions d'ammoniac, de protoxyde d'azote, de méthane, de gaz carbonique et de vapeur d'eau lors de l'élevage de porcs charcutiers sur litière accumulée de sciure: quantification et corrélations avec le niveau d'activités des animaux
Delcourt, M.; Vandenheede, Marc ULg; Desiron, A. et al

in Annales de Médecine Vétérinaire (2001), 145(6), 357-364

During a 4-month fattening period, emissions of NH3, N2O, CH4, CO2 and H2O from a pig house with fattening pigs on deep litter was measured once a month during four days (one measurement every 30 min ... [more ▼]

During a 4-month fattening period, emissions of NH3, N2O, CH4, CO2 and H2O from a pig house with fattening pigs on deep litter was measured once a month during four days (one measurement every 30 min). The activity rate of the animals was also measured hourly as the mean proportion of standing animals observed each two minutes. The mean daily emissions of gas, calculated per pig, were 9,5 g NH3, 3,2 g N2O, 4,8 g CH4, 1,3 kg CO2 and 3,3 kg water vapour. Emissions increased during the fattening period, the values observed at the end being 50%, 50%, 680% and 1000% higher than those at the beginning, for CO2, H2O, CH4 and NH3 respectively. Emissions of N2O were however higher at the beginning than at the end of the fattening period. The activity rate of the pigs followed a circadian rhythm, pigs being observed in a standing position much more frequently during the day than during the night, especially in the morning, at the end of the afternoon and at the beginning of the evening. The activity rate decreased continuously during the fattening period, from 22,6 +/- 4,1% to 8,8 +/- 0,5%. Within each monthly observation period, the hourly emissions of NH3, CO2 and H2O were positively correlated with the pigs' activity rate, the mean correlation coefficients being 0,61 for NH3, 0,71 for CO2 and 0,75 for water vapour. The correlation coefficients were not significant for N2O and CH4 in periods 2 et 3 but significant in periods 1 and 4 with mean values of -0,55 for N2O and +0,26 for CH4. [less ▲]

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See detailEmissions de vapeur d’eau et bilan azoté lors de l’élevage de porcelets sevrés sur litière accumulée de sciure
Nicks, Baudouin ULg; Laitat, Martine ULg; Vandenheede, Marc ULg et al

in Annales de Zootechnie (2000), 49

Five batches of a total of 180 weaned pigs were reared successively in an experimental room on 30 cm deep litter without cleaning between the batches. The litter was a mixture of sawdust from coniferous ... [more ▼]

Five batches of a total of 180 weaned pigs were reared successively in an experimental room on 30 cm deep litter without cleaning between the batches. The litter was a mixture of sawdust from coniferous and beech trees. Water was added to the Litter every 10 days to lower the dust concentration in the room. The total amounts of sawdust and water used were respectively 21.3 kg per pig and 10.21 per pig. The mean temperature of the litter at 20 cm depth recorded during each of the 5 periods varied from 32.5 degrees C to 41.8 degrees C. The average liveweight of the pigs at the beginning and at the end of the post-weaning period was respectively 7.9 +/- 1.2 kg and 24.5 +/- 4.2 kg. The average daily gain was 392 +/- 87 g. The temperature and the relative humidity of the air inside and outside the experimental room and the ventilation rate were continuously recorded in order to calculate the water vapour emission for each batch. The amount of water vapour produced was significantly correlated to the water consumption of the pigs and reached an average of 1 732 g per pig per day. This amount is 36% greater than the reference used for pigs on slatted floors. This value may be used as a reference to calculate the minimum ventilation rate for piggeries with pigs on sawdust deep litters. The amount of compost produced was 19.9 kg per pig with a dry matter content of 44.7%. The amount of nitrogen in the compost was 231 g per pig which is about 50% lower than the reference used for the slurry. The volatile nitrogen emissions are thus much higher from composts than from slurries [less ▲]

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See detailEmissions gazeuses en élevage porcin et modes de réduction : revue bibliographique
Degre, Aurore ULg; Verheve, Didier; Debouche, Charles ULg

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2001), 5(3), 135-143

Detailed reference viewed: 50 (22 ULg)
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See detailÉmissions gazeuses liées au séchage convectif de boues de station d’épuration
Fraikin, Laurent ULg; Herbreteau, Benjamin; Nicol, François et al

in SFGP (Ed.) Récents Progrès en Génie des Procédés - N°98 - A la croisée des sciences et des cultures pour relever les défis industriels du XXIème siècle - Actes du 12ème Congrès de la Société Française de Génie des Procédés, Marseille, France, 14-16 octobre 2009 (2009, October)

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See detailEmissions investigation for a novel medical waste incinerator
Xie, Rong; Li, Weijie; Li, Jie ULg et al

in Journal of Hazardous Materials (2009), 166(1), 365-371

Medical waste constitutes one of the waste streams that should be dealt with special priority due to its potential negative impact on public health and on the environment. Incineration is a process that ... [more ▼]

Medical waste constitutes one of the waste streams that should be dealt with special priority due to its potential negative impact on public health and on the environment. Incineration is a process that is widely used for the treatment of medical waste. However, self-supporting combustion of medical waste cannot avoid releasing many hazardous pollutants into our environment. The most favored solutions are firing additional fuels of high calorific value and direct purification by air pollution control devices (APCD). This process entails not only large first time investment but also an increase in the operation cost. A novel incinerator is proposed for better utilization of energy of the incineration process. Its originality is essen-tially due to combining a feeder, a rotary grate, a cylindrical gasifier and a “coaxial” secondary combustion chamber into a unique unit. The structure of the incinerator as well as the principle of the incineration process is presented in this paper. A full-scale trial of the novel incinerator with APCD was carried out from March to May 2008 to investigate how the distinct configuration influenced the incineration process. Data on PM, CO, NOX ,O2 were recorded by a continuous emission monitoring system during the study period. Heavy metals and PCCD/Fs were also sampled and measured. Measuring results were compared with the China and U.S. EPA guidelines. The concentrations of contaminants were below their respective limits in emission control standards. Results from testing the novel medical waste incinerator confirmed that this technology has a good suitability for neutralization of medical wastes and purification of flue gases. [less ▲]

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