196,173 research outputs found
Hail nets enhance disruption of sexual communication by synthetic pheromone in codling moth
No full textWe hypothesized that polyethylene anti-hail nets interact with synthetic pheromone in disrupting the sexual communication of codling moth Cydia pomonella L. We tested this hypothesis through the release and recapture of m ales in field cages. This set-up allowed normalisation of the male population during the treatments. The effect of the net was also estimated through recording additional parameters such as wind speed, temperature within the canopy, and pheromone emissions from mating disruption dispensers. The experiments were carried out in orchards with or without hail nets, and with or without pheromone disruption treatment. In the release and recapture assay the hail net significantly decreased the success of sexual communication in association with the mating disruption treatment. In plots without synthetic pheromone, the net did not affect communication between the sexes. Both wind speed and canopy temperatures were mitigated by the presence of the net. Pheromone emissions from disruption dispensers did not differ for covered and uncovered plots. The increase in communication disruption with the hail net is of practical interest and opens up possibilities for extending the use of mating disruption to orchards where climatic or topographic features currently limit the efficacy of this sustainable metho
TaSiN diffusion barriers deposited by reactive magnetron sputtering
No full textInternational audienceDue to its resistance to oxidation, TaSiN is a promising candidate as an electrically conductive barrier layer for integration of high permittivity oxides in advanced memory devices. In this study we report on the properties of TaSiN thin films deposited by reactive magnetron sputtering of a TaSi2 target in an Ar/N-2 atmosphere. We especially focus on the influence of deposition parameters (pressure and power density) on TaSiN film properties. To study oxidation resistance, films are processed by rapid thermal annealing in O-18(2) at 650 degrees C. The concentration depth profiles of O-18 were measured via the narrow resonance of O-18(p,alpha)N-15 at 151 keV (FWHM = 100 eV). Whatever the power density, films deposited above 2 Pa are porous and exhibit high resistivity. Ta26Si47N27 deposited at 0.5 Pa with a power density of 2.65 W/cm(2) exhibits high density, low resistivity, and good oxidation resistance. (c) 2006 Elsevier B.V. All rights reserved
Fast Direct Injection Mass-Spectrometric Characterization of Stimuli for Insect Electrophysiology by Proton Transfer Reaction-Time of Flight Mass-Spectrometry (PTR-ToF-MS)
No full textElectrophysiological techniques are used in insect neuroscience to measure the response of olfactory neurons to volatile odour stimuli. Widely used systems to deliver an olfactory stimulus to a test insect include airstream guided flow through glass cartridges loaded with a given volatile compound on a sorbent support. Precise measurement of the quantity of compound reaching the sensory organ of the test organism is an urgent task in insect electrophysiology. In this study we evaluated the performances of the recent realised proton transfer reaction-time of flight mass-spectrometry (PTR-ToF-MS) as a fast and selective gas sensor. In particular, we characterised the gas emission from cartridges loaded with a set of volatile compounds belonging to different chemical classes and commonly used in electrophysiological experiments. PTR-ToF-MS allowed a fast monitoring of all investigated compounds with sufficient sensitivity and time resolution. The detection and the quantification of air contaminants and solvent or synthetic standards impurities allowed a precise quantification of the stimulus exiting the cartridge. The outcome of this study was twofold: on one hand we showed that PTR-ToF-MS allows monitoring fast processes with high sensitivity by real time detection of a broad number of compounds; on the other hand we provided a tool to solve an important issue in insect electrophysiology
Study of poly-Si/TaSiN/Pt structure for stacked capacitors
No full textABSTRACTDue to its high oxidation resistance, TaSiN is a promising candidate as an electrically conductive barrier layer for integration of high permittivity oxides in advanced memory devices. In this work, we report on the properties of TaSiN thin films deposited by reactive magnetron sputtering of a TaSi2 target. We have mainly studied the influence of deposition pressure and power density on film properties (composition, density, resistivity). The oxidation resistance of TaSiN films has been investigated at typical conditions for crystallization of perovskite dielectrics. The as-deposited and annealed samples were characterized using Rutherford backscattering spectroscopy and nuclear reaction analysis for atomic composition and XPS for chemical bonding. To study oxidation resistance, films have been processed in 18O2. The concentration depth profiles of 18O was measured after thermal treatments via the narrow resonances of 18O(p,α)15N at 151 keV (fwhm=100eV). The different results suggest that a pressure of 0.5 Pa, a power density of 2.63W/cm2 and a gas flow ratio N2/Ar of 5% allow to perform TaSiN films with high density, low resistivity and good oxidation resistance.</jats:p
Fano-Mori contractions of high length on projective varieties with terminal singularities
No full textLet X be a projective variety with Q-factorial terminal singularities and let L be an ample Cartier divisor on X.
We prove that if f is a birational contraction associated to an extremal ray R subset of such that R center dot(K-X+(n-2)L)< 0, then f is a weighted blow-up of a smooth point.
We then classify divisorial contractions associated to extremal rays R such that R center dot(K-X+rL)< 0, where r is a non-negative integer, and the fibres of f have dimension less than or equal to r+1
Plant volatiles for detection of migrating apple fruit moth
No full textApple fruit moth Argyresthia conjugella (Zeller) (Lepidoptera: Argyresthiidae) is the most important insect pest in apples in Fennoscandia. Its principle host is the masting forest tree rowan Sorbus aucuparia. Damage to apple occurs only in intermasting years when rowan produces low crop. In
these years, populations of apple fruit moth move from the forest to the nearby orchards to lay their eggs on apple fruits. Volatile plant compounds may be used to trap migrating females searching for the alternative host during intermasting years (Bengtsson et al., 2006). Plant volatiles released by rowan as well as by apple were found to attract both sexes of A. conjugella in field experiments (Bengtsson et al., 2006). Additional research effort is needed to improve the attraction and thus to
develop a monitoring tool to detect the timing of female migration to apple in order to precisely apply control measures. In this study we present data from field monitoring experiments done in 2007 and 2008 in both rowan and apple crops. Tetra traps were lured with a rubber septum loaded with a blend of compounds diluted in hexane. Traps were deployed during the migration of the moths (June and July). In 2007 we carried out a field test in apple with the aim to screen for behaviorally active compounds beside those already described by Bengtsson et al. (2006). In apple, higher attraction was observed for a blend of 2-phenyl ethanol, methyl salicylate and decanal followed by a blend of 2-phenyl ethanol and anethole. Although to a lower level, also blends containing Z-jasmone and (Z)-3-
hexenyl-2-methyl-butanoate were significantly attractive. In a rowan forest, only the 2-phenyl ethanol and anethole blend was attractive. In 2008, in rowan the best attractant was the two component blend of 2-phenyl ethanol and anethole in a 1:1 ratio, confirming the results of 2007. This blend caught moths in a sex ratio similar to that detected by visual inspection. In apple, instead, this blend caught only few males. However, a 6 component blend including methyl salicylate, decanal, Z-jasmone and (Z)-3-hexenyl-2-methylbutanoate beside 2-phenyl ethanol and anethole, was in apple the best female attractant. We detected
insects by both visual inspections and trapping in a rowan stand, whilst only traps baited with the new 6 component blend could detect migrating insects in apple orchards. Although the number in apple was low due to the fact that 2008 was a low-attack season and the majority of the moths remained in
the rowan stands, our preliminary results open the possibility of developing a specific lure to be used in apple orchards as a warning tool for population control of apple fruit moth. In our field experiments, we observed an effect of the crop on the attraction to the different blends. It is possible that the odors from the crop have a behavioral effect on the attraction of the
blends, by providing a background level of volatiles which may interact with the plume released by our traps. This effect has been recently reported in a wind tunnel study (Knudsen et al., 2008), where apple fruit moth females were attracted to 2-phenyl ethanol only in the presence of rowan vegetation as background. It thus appears that improvements of blend composition for field monitoring in apple orchards may be achieved by additional field tests in damage years in combination with wind tunnel
studies
Effective nonvanishing for fano weighted complete intersections
No full textWe show that the Ambro–Kawamata nonvanishing conjecture holds true for a quasismooth WCI X which is Fano or Calabi–Yau, i.e., we prove that, if H is an ample Cartier divisor on X, then |H| is not empty. If X is smooth, we further show that the general element of |H| is smooth. We then verify the Ambro– Kawamata conjecture for any quasismooth weighted hypersurface. We also verify Fujita’s freeness conjecture for a Gorenstein quasismooth weighted hypersurface. For the proofs, we introduce the arithmetic notion of regular pairs and highlight some interesting connections with the Frobenius coin problem
Properties of TaSiN thin films deposited by reactive radio frequency magnetron sputtering
No full textTaSiN is a promising material for application as electrically conductive diffusion barrier for the integration of high permittivity perovskite materials in integrated circuits. TaSiN thin films were deposited by reactive radio frequency magnetron sputtering using TaSi and TaSi2.7 targets in an Ar/N-2 atmosphere. The sputter power was varied in order to achieve different TaSiN compositions. The stoichiometry of as-deposited films was estimated using Rutherford backscattering spectroscopy. The as-deposited TaSiN thin films are amorphous. Their crystallization temperature is above 700 degrees C and increases with higher nitrogen content. They have metallic conduction and ohmic behavior. The resistivity of as deposited films is in the range from 10(-6)Omega m up to 10(-3)Omega m and increases with nitrogen content. It was found that p(++)-Si/Ta21Si57N21 develops unacceptable high contact resistance. Introducing an intermediate Pt layer the stack p(++)-Si/Pt/Ta21Si57N21 had a good conductive properties and good thermal stability at 700 degrees C. (C) 2012 Elsevier B.V. All rights reserved
Stone pine volatiles and host selection by Tomicus destruens (Wollaston) (Coleoptera: Curculionidae, Scolytinae)
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