References of "Liu, Y"
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See detailModelling phytoplankton succession and nutrient transfer along the Scheldt estuary (Belgium, The Netherlands)
Gypens, N.; Delhez, Eric ULg; Vanhoutte-Brunier, A. et al

in Journal of Marine Systems (2013), 128

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See detailNumerical study of the thermo-hydro-mechanical behavior of GMZ bentonite
Chen, L.; Wang, J.; Liu, Y. et al

Conference (2012, October)

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See detailGlobal analysis of gene expression in the skin of mice after a 92 days journey in microgravity.
Neutelings, Thibaut ULg; Liu, Y.; Cancedda, R. et al

Poster (2012, May 04)

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See detailNumerical thermo-hydro-mechanical modeling of compacted bentonite inChina-mock-up testfor deep geological disposal
Chen, L; Wang, J; Liu, Y et al

in Journal of Rock Mechanics and geotechnical engineering (2012), 4(2), 183-192

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See detailGlobal analysis of gene expression in the skin of mice after a 92 days journey in microgravity.
Neutelings, Thibaut ULg; Liu, Y.; Cancedda, R et al

Conference (2012)

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See detailE-b-farnesene synergizes the influence of an insecticide to improve control of cabbage aphids in China
Cui, L.L; Dong, J.; Francis, Frédéric ULg et al

in Crop Protection (2012)

Extensive use of pesticides to control insect pests can have negative effects on the environment, natural enemies and food safety. The aphid alarm pheromone, E-b-farnesene (Ebf), appears to hold strong ... [more ▼]

Extensive use of pesticides to control insect pests can have negative effects on the environment, natural enemies and food safety. The aphid alarm pheromone, E-b-farnesene (Ebf), appears to hold strong potential for controlling a wide variety of aphid pests. To understand the control potential of Ebf, we used field experiments in a factorial design to test its influence and that of the insecticide imidacloprid on populations of aphids Lipaphis erysimi (Kaltenbach) and Myzus persicae (Sulzer) on Chinese cabbage, Brassica rapa pekinensis (Brassicales: Brassicaceae). Our results showed imidacloprid treatment alone can significantly decrease aphid populations, and that combining insecticide with Ebf further reduced numbers of apterous aphids at distances of 5 m from pheromone emitters in two years of our experiments. Our results demonstrate that imidacloprid can be effective in reducing the abundance of aphids in Chinese cabbage fields, but the degree of control can be even stronger in the presence of Ebf. [less ▲]

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See detailThe functional significance of E-b-Farnesene: Does it influence the populations of aphid natural enemies in the fields?
Cui, L-L; Francis, Frédéric ULg; Heuskin, Stéphanie ULg et al

in Biological Control (2012)

Aphids cause much damage to Chinese cabbage in northern China. Over reliance on pesticides have large environmental and human health costs that compel researchers to seek alternative management tactics ... [more ▼]

Aphids cause much damage to Chinese cabbage in northern China. Over reliance on pesticides have large environmental and human health costs that compel researchers to seek alternative management tactics for aphid control. The component of aphid alarm pheromone, E-b-Farnesene (EbF), extracted from Matricaria chamomilla L., which attracts natural enemies in the laboratory, may have significant implications for the design of cabbage aphid control strategies. The purpose of this paper is to understand the effects of EbF on natural enemies to cabbage aphid control in Chinese cabbage fields. Ladybeetles on Chinese cabbage leaves in EbF released plots and Aphidiidae in EbF released yellow traps were significantly higher than those of in controls. No significant differences were detected in the interactions of different treatments and the two years for all natural enemies. More important, lower aphid densities were found in EbF released plots. Our results suggested that the EbF extracted from M. chamomilla L. could attract natural enemies to reduce cabbage aphids in the Chinese cabbage fields. [less ▲]

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See detailScientific Assessment of Ozone Depletion: 2010, Chapter 2 - Stratospheric Ozone and Surface Ultraviolet Radiation
Douglass, A.; Fioletov, V.; Godin-Beekmann, Sophie et al

Report (2011)

As a result of the Montreal Protocol, ozone is expected to recover from the effect of ozone-depleting substances (ODSs) as their abundances decline in the coming decades. The 2006 Assessment showed that ... [more ▼]

As a result of the Montreal Protocol, ozone is expected to recover from the effect of ozone-depleting substances (ODSs) as their abundances decline in the coming decades. The 2006 Assessment showed that globally averaged column ozone ceased to decline around 1996, meeting the criterion for the first stage of recovery. Ozone is expected to increase as a result of continued decrease in ODSs (second stage of recovery). This chapter discusses recent observations of ozone and ultraviolet radiation in the context of their historical records. Natural variability, observational uncertainty, and stratospheric cooling necessitate a long record in order to attribute an ozone increase to decreases in ODSs. The primary tools used in this Assessment for prediction of ozone are chemistry-climate models (CCMs). These CCMs are designed to represent the processes determining the amount of stratospheric ozone and its response to changes in ODSs and greenhouse gases. Eighteen CCMs have been recently evaluated using a variety of process-based compari-sons to measurements. The CCMs are further evaluated here by comparison of trends calculated from measurements with trends calculated from simulations designed to reproduce ozone behavior during an observing period. [less ▲]

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See detailGeophysical validation of MIPAS-ENVISAT operational ozone data
Cortesi, U.; Lambert, J. C.; De Clercq, C. et al

in Atmospheric Chemistry and Physics (2007), 7(18), 4807-4867

The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS), on-board the European ENVIronmental SATellite (ENVISAT) launched on 1 March 2002, is a middle infrared Fourier Transform spectrometer ... [more ▼]

The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS), on-board the European ENVIronmental SATellite (ENVISAT) launched on 1 March 2002, is a middle infrared Fourier Transform spectrometer measuring the atmospheric emission spectrum in limb sounding geometry. The instrument is capable to retrieve the vertical distribution of temperature and trace gases, aiming at the study of climate and atmospheric chemistry and dynamics, and at applications to data assimilation and weather forecasting. MIPAS operated in its standard observation mode for approximately two years, from July 2002 to March 2004, with scans performed at nominal spectral resolution of 0.025 cm(-1) and covering the altitude range from the mesosphere to the upper troposphere with relatively high vertical resolution (about 3 km in the stratosphere). Only reduced spectral resolution measurements have been performed subsequently. MIPAS data were re-processed by ESA using updated versions of the Instrument Processing Facility (IPF v4.61 and v4.62) and provided a complete set of level-2 operational products (geo-located vertical profiles of temperature and volume mixing ratio of H2O, O-3, HNO3, CH4, N2O and NO2) with quasi continuous and global coverage in the period of MIPAS full spectral resolution mission. In this paper, we report a detailed description of the validation of MIPAS-ENVISAT operational ozone data, that was based on the comparison between MIPAS v4.61 (and, to a lesser extent, v4.62) O-3 VMR profiles and a comprehensive set of correlative data, including observations from ozone sondes, ground-based lidar, FTIR and microwave radiometers, remote-sensing and in situ instruments on-board stratospheric aircraft and balloons, concurrent satellite sensors and ozone fields assimilated by the European Center for Medium-range Weather Forecasting. A coordinated effort was carried out, using common criteria for the selection of individual validation data sets, and similar methods for the comparisons. This enabled merging the individual results from a variety of independent reference measurements of proven quality (i.e. well characterized error budget) into an overall evaluation of MIPAS O-3 data quality, having both statistical strength and the widest spatial and temporal coverage. Collocated measurements from ozone sondes and ground-based lidar and microwave radiometers of the Network for the Detection Atmospheric Composition Change (NDACC) were selected to carry out comparisons with time series of MIPAS O-3 partial columns and to identify groups of stations and time periods with a uniform pattern of ozone differences, that were subsequently used for a vertically resolved statistical analysis. The results of the comparison are classified according to synoptic and regional systems and to altitude intervals, showing a generally good agreement within the comparison error bars in the upper and middle stratosphere. Significant differences emerge in the lower stratosphere and are only partly explained by the larger contributions of horizontal and vertical smoothing differences and of collocation errors to the total uncertainty. Further results obtained from a purely statistical analysis of the same data set from NDACC ground-based lidar stations, as well as from additional ozone soundings at middle latitudes and from NDACC ground-based FTIR measurements, confirm the validity of MIPAS O-3 profiles down to the lower stratosphere, with evidence of larger discrepancies at the lowest altitudes. The validation against O-3 VMR profiles using collocated observations performed by other satellite sensors (SAGE II, POAM III, ODIN-SMR, ACE-FTS, HALOE, GOME) and ECMWF assimilated ozone fields leads to consistent results, that are to a great extent compatible with those obtained from the comparison with ground-based measurements. Excellent agreement in the full vertical range of the comparison is shown with respect to collocated ozone data from stratospheric aircraft and balloon instruments, that was mostly obtained in very good spatial and temporal coincidence with MIPAS scans. This might suggest that the larger differences observed in the upper troposphere and lowermost stratosphere with respect to collocated ground-based and satellite O-3 data are only partly due to a degradation of MIPAS data quality. They should be rather largely ascribed to the natural variability of these altitude regions and to other components of the comparison errors. By combining the results of this large number of validation data sets we derived a general assessment of MIPAS v4.61 and v4.62 ozone data quality. A clear indication of the validity of MIPAS O-3 vertical profiles is obtained for most of the stratosphere, where the mean relative difference with the individual correlative data sets is always lower than +/- 10%. Furthermore, these differences always fall within the combined systematic error (from 1 hPa to 50 hPa) and the standard deviation is fully consistent with the random error of the comparison (from 1 hPa to similar to 30-40 hPa). A degradation in the quality of the agreement is generally observed in the lower stratosphere and upper troposphere, with biases up to 25% at 100 hPa and standard deviation of the global mean differences up to three times larger than the combined random error in the range 50-100 hPa. The larger differences observed at the bottom end of MIPAS retrieved profiles can be associated, as already noticed, to the effects of stronger atmospheric gradients in the UTLS that are perceived differently by the various measurement techniques. However, further components that may degrade the results of the comparison at lower altitudes can be identified as potentially including cloud contamination, which is likely not to have been fully filtered using the current settings of the MIPAS cloud detection algorithm, and in the linear approximation of the forward model that was used for the a priori estimate of systematic error components. The latter, when affecting systematic contributions with a random variability over the spatial and temporal scales of global averages, might result in an underestimation of the random error of the comparison and add up to other error sources, such as the possible underestimates of the p and T error propagation based on the assumption of a 1 K and 2% uncertainties, respectively, on MIPAS temperature and pressure retrievals. At pressure lower than 1 hPa, only a small fraction of the selected validation data set provides correlative ozone data of adequate quality and it is difficult to derive quantitative conclusions about the performance of MIPAS O-3 retrieval for the topmost layers. [less ▲]

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