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See detailFirst evidence for a resolved structure in the inner Vega system
Absil, Olivier ULg

Poster (2005, October 01)

We report on infrared interferometric observations of Vega obtained in May and June 2005 with the FLUOR instrument installed on the CHARA interferometer. The combination of short and long baselines has ... [more ▼]

We report on infrared interferometric observations of Vega obtained in May and June 2005 with the FLUOR instrument installed on the CHARA interferometer. The combination of short and long baselines has allowed us to study the brightness distribution of the stellar photosphere, and to detect a spatial component which is over-resolved at our lowest resolution (~15 milli-arcseconds). This would be attributed to structure much larger than Vega, but within the CHARA/FLUOR field-of-view (about 1 arcsecond in radius, i.e., 8 AU around Vega). The contrast between the resolved flux and the central star is only slightly above the 1% level in K band. This emission could be interpreted as the first direct detection of thermal and/or scattered light emanating from the innermost part of the Vega debris disk, which is thought to be continuously replenished by asteroid collisions and/or comet evaporation. The possibility of a close stellar or sub-stellar companion is also investigated. [less ▲]

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See detailFirst evidence of a Lysobacter member as a biological control agent of Plasmopara viticola
Puopolo, G.; Jourdan, E.; Ongena, Marc ULg et al

in Bulletin OILB/SROP = IOBC/WPRS Bulletin (2013), 86

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See detailFirst Evidence of a Volatile Sex Pheromone in Harmonia axyridis (Pallas)
Fassotte, Bérénice ULg; Fischer, Christophe ULg; Durieux, Delphine ULg et al

Poster (2013, October)

Until now, no volatile sex pheromone has been highlighted in Coccinellidae but various studies have suggested the existence of such molecules. In the present work, we have sampled volatile organic ... [more ▼]

Until now, no volatile sex pheromone has been highlighted in Coccinellidae but various studies have suggested the existence of such molecules. In the present work, we have sampled volatile organic compounds released in the headspace of virgin females in the multicolored Asian ladybeetle, Harmonia axyridis (Pallas), that were either allowed or not to feed on pea aphids (Acyrthosiphon pisum Harris). When fed on aphids, virgin females showed a stereotypical “calling behavior”, commonly associated with the emission of a sex pheromone in several Coleoptera species. Behavioral assays conducted with calling females in a four-arm olfactometer demonstrated that the blend of released volatile compounds was attractive at a distance for males, but not for other females. The headspace of virgin females that were not previously fed with aphids was not attractive for either sex. GC-MS analyses revealed the presence of five compounds in the volatile blend: (–)-β-caryophyllene, β-elemene, methyl-eugenol, α-humulene and α-bulnesene. Subsequently, we have collected and quantified the constituents from the blend over a period of 9 days after exposure to aphids. All five compounds were produced exclusively after feeding virgin females with aphids, and their quantity significantly increased during the whole period of collection. (–)-β-caryophyllene was found to be the major constituent, representing between 80 and 86 % of the total blend. All these results could promote the development of more specific and efficient management methods to manipulate the movements of this invasive ladybeetle and to reduce its negative impacts on biodiversity. [less ▲]

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See detailFirst evidence of a volatile sex pheromone in the invasive Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae)
Fassotte, Bérénice ULg; Fischer, Christophe ULg; Durieux, Delphine ULg et al

Conference (2014, April 02)

Data about sex pheromones, or any semiochemicals that play a role in Coccinellid mating, remain limited. Since years, various studies and behavioral observations have hypothesized that such molecules are ... [more ▼]

Data about sex pheromones, or any semiochemicals that play a role in Coccinellid mating, remain limited. Since years, various studies and behavioral observations have hypothesized that such molecules are involved in sexual communication of ladybeetles. In this study, we collected volatile organic compounds released by virgin females of the multicolored Asian ladybeetle, Harmonia axyridis (Pallas), which were either allowed or not allowed to feed on aphids. In the presence of aphids, virgin females exhibited “calling behavior”, which has been associated with the emission of a sex pheromone in several Coleoptera species. Bioassays showed that these females released a blend of volatile compounds that is involved in the attraction of males. Gas Chromatography-Mass Spectrometry analyses highlighted specific volatile cues emanating from females, whereas males did not produce these compounds. Five components were identified: (–)-β-caryophyllene, β elemene, methyl-eugenol, α humulene, and α bulnesene. All compounds were produced after virgin females were fed aphids, and their quantity increased across the experimental period. The results confirm that female H. axyridis produce a volatile sex pheromone. Therefore, this study provides important biological information that could promote the development of efficient pest control management methods to manipulate the movements of this invasive ladybeetle, and to reduce its negative impacts on biodiversity. [less ▲]

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See detailFirst evidence of a volatile sex pheromone in the invasive Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae)
Fassotte, Bérénice ULg; Fischer, Christophe ULg; Durieux, Delphine ULg et al

Conference (2013, September 10)

Until now, volatile sex pheromone have not been identified in the Coccinellidae, although various studies have suggested the existence of such molecules. In this work, we have sampled volatile organic ... [more ▼]

Until now, volatile sex pheromone have not been identified in the Coccinellidae, although various studies have suggested the existence of such molecules. In this work, we have sampled volatile organic compounds released in the headspace of virgin females of the multicolored Asian ladybeetle, Harmonia axyridis (Pallas), that were either allowed or not to feed on pea aphids (Acyrthosiphon pisum Harris). When fed on aphids, virgin females showed a stereotypical “calling behavior”, commonly associated with the emission of a sex pheromone in several Coleoptera species. Behavioral assays conducted with calling females in a four-arm olfactometer demonstrated that the blend of released volatile compounds was attractive for males, but not for other females. The headspace of virgin females that were not previously fed with aphids was not attractive for either sex. GC-MS analyses revealed the presence of five compounds in the volatile blend: (–)-β-caryophyllene, β elemene, methyl-eugenol, α-humulene and α-bulnesene. Subsequently, we have collected and quantified the constituents from the blend over a period of 9 days after exposure to aphids. All five compounds were produced exclusively after feeding virgin females with aphids, and their quantity significantly increased during the whole period of collection. (–)-β-caryophyllene was found to be the major constituent, representing between 80 and 89 % of the total blend. These results could promote the development of more specific and efficient management methods to manipulate the movements of this invasive ladybeetle and to reduce its negative impacts on biodiversity. [less ▲]

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See detailFirst evidence of deuterotokous parthenogenesis in the tomato leafminer, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae)
Caparros Megido, Rudy ULg; Haubruge, Eric ULg; Verheggen, François ULg

in Journal of Pest Science (2012)

The tomato leafminer, Tuta absoluta (Lepidoptera: Gelechiidae), originates from South America and is now considered to be one of the most damaging invasive pests of tomatoes in the Mediterranean Basin ... [more ▼]

The tomato leafminer, Tuta absoluta (Lepidoptera: Gelechiidae), originates from South America and is now considered to be one of the most damaging invasive pests of tomatoes in the Mediterranean Basin countries of Europe and North Africa. The preventing pest mating control methods include: (1) the use of synthetic pheromones for male attraction and annihilation inside insecticide-containing traps; (2) mating disruption by saturating the atmosphere with sex pheromones which alter the ability of males to locate females; and (3) massive applications of sterile males to alter the overall reproductive success of the pest population. However, all these methods achieve only a poor success rate in controlling T. absoluta populations under greenhouse conditions. Sex pheromone management and sterile insect techniques are both based on an important biological trait: the insect must breed through sexual reproduction. Here, we report for the first time laboratory evidence of deuterotokous parthenogenesis, an asexual reproduction where both males and females are produced from unfertilized eggs. We discuss the consequences for T. absoluta control strategies. [less ▲]

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See detailFirst evidence of progenesis in Triturus (Amphibia)
Denoël, Mathieu ULg; Joly, Pierre

Poster (1998)

Paedomorphosis is defined as the retention of subadult morphology in reproductive adults. Two main processes can produce this heterochronic pattern : neoteny and progenesis, but progenesis has not been ... [more ▼]

Paedomorphosis is defined as the retention of subadult morphology in reproductive adults. Two main processes can produce this heterochronic pattern : neoteny and progenesis, but progenesis has not been yet demonstrated in newts. Distinction between them can be obtained from the determination of age at first reproduction using the squelettochronological method. In this study, we sampled more than 300 Triturus alpestris in two populations : one in a French Alpine lake and the other in an Italian pond. Results show that paedomorphs from the Italian pond are mature earlier and at a smaller size than metamorphs (Progenesis) whereas paedomorphic and metamorphic newts from the French population do not differ in size and age (Neoteny). Adaptative significance of Paedomorphosis is discussed in relation to the stability of the aquatic habitat [less ▲]

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See detailFirst evidence of pulsations in Vega?. Results of today's most extensive spectroscopic search
Böhm, T.; Lignières, F.; Wade, G. et al

in Astronomy and Astrophysics (2012), 537

Context. The impact of rapid rotation on stellar evolution theory remains poorly understood as of today. Vega is a special object in this context as spectroscopic and interferometric studies have shown ... [more ▼]

Context. The impact of rapid rotation on stellar evolution theory remains poorly understood as of today. Vega is a special object in this context as spectroscopic and interferometric studies have shown that it is a rapid rotator seen nearly pole one, a rare orientation particularly interesting for seismic studies. In this paper, we present a first systematic search for pulsations in Vega. <BR /> Aims: The goal of the present work is to detect for the first time pulsations in a rapidly rotating star seen nearly pole-on. <BR /> Methods: Vega was monitored in quasi-continuous high-resolution echelle spectroscopy. A total of 4478 spectra were obtained. More precisely in 2008 we obtained 1213 spectra during 19.9 h on 3 nights (26th, 27th and 29th of July 2008) with NARVAL/TBL (at R = 65 000 and R = 75 000), in 2009 we obtained 1293 spectra during 13.7 h on 3 nights (9th-11th of September 2009) with ESPaDOnS/CFHT (at R = 68 000) and in 2010 we gathered again 1972 with NARVAL/TBL during 28.8 h on five nights (July 15th-19th). This data set should represent the most extensive high S/N, high resolution quasi-continuous survey obtained on Vega as of today. Least square deconvolved (LSD) profiles were obtained for each spectrum representing the photospheric absorption profile potentially deformed by the presence of pulsations. In addition, we calculated for each spectrum a telluric line LSD profile subsequently used as radial velocity reference. LSD profile centroids were adjusted and velocity differences (stellar-telluric) determined. These residual velocities were analysed and periodic low amplitude variations, potentially indicative of stellar pulsations, detected. In a subsequent step, the temporal line profile variations during the longest (2010) data set was calculated for each individual velocity bin of 1.8 km s[SUP]-1[/SUP] by computing a 2D (velocity-frequency) Lomb-Scargle periodogram. <BR /> Results: Based on high resolution echelle spectroscopy, we have obtained indications of periodic variations of very small amplitudes within the residual radial velocity curves of Vega. All three data sets revealed the presence of residual periodic variations: 5.32 and 9.19 d[SUP]-1[/SUP] (A ≈ 6 m s[SUP]-1[/SUP]) in 2008, 12.71 and 13.25 d[SUP]-1[/SUP] (A ≈ 8 m s[SUP]-1[/SUP]) in 2009 and 5.42 and 10.82 d[SUP]-1[/SUP] (A ≈ 3-4 m s[SUP]-1[/SUP]) in 2010. However, it is too early to conclude that the variations are due to stellar pulsations, and a confirmation of the detection with a highly stable spectrograph is a necessary next step. <BR /> Conclusions: If pulsations are confirmed, their very small amplitudes show that the star would belong to a category of very "quiet" pulsators. Based on observations obtained at the Bernard Lyot Telescope (TBL, Pic du Midi, France) of the Midi-Pyrénées Observatory, which is operated by the Institut National des Sciences de l'Univers (INSU) of the Centre National de la Recherche Scientifique of France (CNRS), and at the Canada-France-Hawaii Telescope (CFHT), which is operated by the National Research Council of Canada, INSU/CNRS and the University of Hawaii. [less ▲]

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See detailFirst evidence of the possible implication of the 11-deoxycorticosterone (DOC) in immune activity of Eurasian perch (Perca fluviatilis, L.): Comparison with cortisol
Mathieu, Cédric; Mila, Sylvain; Mandiki, Robert et al

in Comparative Biochemistry & Physiology Part A : Molecular & Integrative Physiology (2013), 165(2), 149-158

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See detailFirst example of an unsymmetrical difunctional monomer polymerizable by two living/controlled methods
Mecerreyes, David; Humes, J.; Miller, R. D. et al

in Macromolecular Rapid Communications (2000), 21(11), 779-784

In this paper the synthesis and (co)polymerizations of 4-(acryloyloxy)-epsilon-caprolactone are reported. This new monomer can be polymerized in a living/controlled way by two different polymerization ... [more ▼]

In this paper the synthesis and (co)polymerizations of 4-(acryloyloxy)-epsilon-caprolactone are reported. This new monomer can be polymerized in a living/controlled way by two different polymerization mechanisms: atom transfer radical polymerization (ATRP) and ring-opening polymerization (ROP). ATRP, which was carried out at 90 degrees C using NiBr2(PPh3)(2), leads to new polyacrylates containing pendant caprolactone functionalities with controlled molecular weights and narrow polydispersities (M-w/M(p)similar to 1.1). Alternatively, ROP of this functional epsilon-caprolactone bearing a pendant acrylate functionality leads to new poly(4-(acryloyloxy) caprolactone) as well as random copolymers when epsilon-caprolactone and L,L-lactide are added as comonomers. The (co)polymerizations were carried out using either (Al((OPr)-Pr-i)(3) in toluene at 25 degrees C or Sn(Oct)(2) as a catalyst at 110 degrees C producing (co)polymers with controlled molecular weights and narrow polydispersities (M-w/M(n)similar to 1.2). As a potential application, the introduction of acrylate pendant groups into the polyesters facilitated the preparation of cross-linked biodegradable materials either thermally or by irradiation with ultraviolet light radical curing. [less ▲]

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See detailFirst example of “click” copper(I) catalyzed azide-alkyne cycloaddition in supercritical carbon dioxide: Application to the functionalization of aliphatic polyesters
Grignard, Bruno ULg; Schmeits, Stephanie ULg; Riva, Raphaël ULg et al

in Green Chemistry (2009), 11

The modification of aliphatic polyesters by the copper(I) catalyzed azide-alkyne cycloaddition (CuAAC) was successfully implemented in supercritical carbon dioxide (scCO2). Due to the remarkable ... [more ▼]

The modification of aliphatic polyesters by the copper(I) catalyzed azide-alkyne cycloaddition (CuAAC) was successfully implemented in supercritical carbon dioxide (scCO2). Due to the remarkable properties of scCO2, the CuAAC reaction turned out to be quantitative even though the aliphatic polyesters used in this work were insoluble in scCO2. Interestingly enough, the conditions were mild enough to prevent polymer degradation from occurring and finally, efficient removal of the catalyst (>96%) was achieved by scCO2 extraction. [less ▲]

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See detailFirst experience with Architect urine NGAL
Cavalier, Etienne ULg; Delanaye, Pierre ULg

Conference (2010, March 25)

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See detailFirst experiences with a Water Vapour Radiometer at the Royal Observatory of Belgium
Pottiaux, Eric; Warnant, René ULg

in Proceedings of EUREF 2002 Symposium (2003)

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See detailFirst experimental evidence of alluaudite-like phosphates with high Li-content: the (Na1-xLix)MnFe2(PO4)3 series (x = 0 to 1).
Hatert, Frédéric ULg; Keller, Paul; Lissner, Falk et al

in European Journal of Mineralogy (2000), 12

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See detailFirst extraction of interference fragmentation functions from e+e- data
Courtoy, Aurore ULg; Bacchetta, A.; Radici, M. et al

in Physical Review. D, Particles, Fields, Gravitation, and Cosmology (2012), 85(11),

We report on the first extraction of interference fragmentation functions from the semi-inclusive production of two hadron pairs in back-to-back jets in e+e- annihilation. A nonzero asymmetry in the ... [more ▼]

We report on the first extraction of interference fragmentation functions from the semi-inclusive production of two hadron pairs in back-to-back jets in e+e- annihilation. A nonzero asymmetry in the correlation of azimuthal orientations of opposite π+π- pairs is related to the transverse polarization of fragmenting quarks through a significant polarized dihadron fragmentation function. Extraction of the latter requires the knowledge of its unpolarized counterpart, the probability density for a quark to fragment in a π +π - pair. Since data for the unpolarized cross section are missing, we extract the unpolarized dihadron fragmentation function from a Monte Carlo simulation of the cross section. © 2012 American Physical Society. [less ▲]

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See detailFirst extraction of valence transversities in a collinear framework
Bacchetta, Alessandro; Courtoy, Aurore ULg; Radici, Marco

in Journal of High Energy Physics [=JHEP] (2013), 1303

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See detailThe first geological maps of Belgium on the web
Anceau, Annick ULg; Nizet, Laurent ULg

Poster (2008, July)

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See detailFirst glances at the transversity parton distribution through dihadron fragmentation functions
Bacchetta, A.; Courtoy, Aurore ULg; Radici, M.

in Physical Review Letters (2011), 107(1),

We present first observations of the transversity parton distribution based on an analysis of pion-pair production in deep-inelastic scattering off transversely polarized targets. The extraction of ... [more ▼]

We present first observations of the transversity parton distribution based on an analysis of pion-pair production in deep-inelastic scattering off transversely polarized targets. The extraction of transversity relies on the knowledge of dihadron fragmentation functions, which we take from electron-positron annihilation measurements. This is the first attempt to determine the transversity distribution in the framework of collinear factorization. © 2011 American Physical Society. [less ▲]

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