Browsing
     by title


0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

or enter first few letters:   
OK
Full Text
See detailLong-term stability of classical photometry
Hensberge, H.; Manfroid, Jean ULg; Sterken, C.

in The Messenger (1992), 70

Detailed reference viewed: 5 (0 ULg)
Full Text
Peer Reviewed
See detailLong-term stratospheric carbon tetrafluoride (CF4) increase inferred from 1985-2004 infrared space-based solar occultation measurements
Rinsland, Curtis P.; Mahieu, Emmanuel ULg; Zander, Rodolphe ULg et al

in Geophysical Research Letters (2006), 33(2),

The long-term stratospheric carbon tetrafluoride (CF4) increase has been determined from infrared high spectral resolution solar occultation Fourier transform spectrometer measurements between 3 and 50 ... [more ▼]

The long-term stratospheric carbon tetrafluoride (CF4) increase has been determined from infrared high spectral resolution solar occultation Fourier transform spectrometer measurements between 3 and 50 hPa (similar to 20 to 40 km altitude) and latitudes from 50 degrees N to 50 degrees S during 1985, 1992, 1993, 1994, and 2004. The 1985 to 1994 measurements were recorded from the ATMOS ( Atmospheric Trace MOlecule Spectroscopy) instrument at 0.01 cm(-1) resolution and in 2004 by the Atmospheric Chemistry Experiment ( ACE) instrument at 0.02 cm(-1) resolution. Stratospheric volume mixing ratios, inferred from a polynomial fit to averages from the time periods considered here, increased from 49.37 +/- 2.60 pptv (10(-12) per unit volume) in 1985 to 58.38 +/- 4.14 pptv in 1992, 60.46 +/- 2.97 pptv in 1993, 60.11 +/- 3.60 pptv in 1994 and to 70.45 +/- 3.40 pptv in 2004. The stratospheric CF4 mixing ratio has continued to increase but at a slower rate than in previous years, for example, (1.14 +/- 0.68)% yr(-1) in 2004 as compared to (2.77 +/- 0.47)% yr(-1) in 1985, 1 sigma. Correlations of CF4 with N2O taking into account the increase of N2O with time also show the increase in the stratospheric CF4 burden over the two decade measurement time span. Our space-based measurements show that the slowdown in the rate of CF4 accumulation previously reported from surface measurements through 1997 has propagated to the stratosphere and is continuing. Citation: Rinsland, C. P., E. Mahieu, R. Zander, R. Nassar, P. Bernath, C. Boone, and L. S. Chiou (2006), Long-term stratospheric carbon tetrafluoride (CF4) increase inferred from 1985-2004 infrared space-based solar occultation measurements, Geophys. Res. Lett., 33, L02808, doi:10.1029/2005GL024709. [less ▲]

Detailed reference viewed: 29 (8 ULg)
Full Text
See detailLong-term study of biogenic volatile organic compound exchanges in a forest ecosystem
Laffineur, Quentin ULg

Doctoral thesis (2012)

The terrestrial biosphere, especially forest ecosystems, emits large quantities of volatile organic compounds (VOCs) which have a significant impact on the atmosphere’s chemical and physical ... [more ▼]

The terrestrial biosphere, especially forest ecosystems, emits large quantities of volatile organic compounds (VOCs) which have a significant impact on the atmosphere’s chemical and physical characteristics. In particular, VOCs are precursors in the formation of ozone and sec-ondary organic aerosols. Isoprene and monoterpenes dominate the total VOC emissions, and methanol is one of the most abundant atmospheric VOCs due to its longer half-life than the other two. The main objective of this thesis was to investigate (using the eddy covariance technique and a proton-transfer-reaction mass spectrometer) the mechanisms of VOC (isoprene, monoterpene and methanol) emission and/or deposition at the scale of a temperate climate forest ecosystem (Vielsalm, Belgium) comprising several species (Fagus sylvatica, Abies alba, Picea Abies and Pseudotsuga menziessi). The eddy covariance technique is very suitable for studying VOC emission/deposition mechanisms at ecosystem level as it does not interfere with the functioning of the ecosystem and it has very good temporal resolution (half an hour). It was used for several months at the Vielsalm site without any major interruption to the measurements. The first measurement period ran from early July to late November 2009 and the second from late March to late November 2010. As well as measuring the VOC exchanges by eddy covari-ance, the climate parameters controlling the exchange mechanisms were also measured. During both these periods the methanol, acetaldehyde, acetone, isoprene, methyl vinyl ke-tone/methacrolein, monoterpene, acetic acid (2010) and formic acid (2010) fluxes were meas-ured. The highest emission levels observed were isoprene and monoterpenes along with methanol, which unlike the first two also showed depositions. The thesis therefore naturally focused on studying these three fluxes, in view of the important role played by these three compounds in atmospheric chemistry and hence the scientific community’s interest in refining the parametrisation of these compounds’ ecosystem/atmosphere exchange models. The study of the isoprene, monoterpene and methanol fluxes has been written up in three original articles which form the main body of this thesis. Because of the heterogeneity of the ecosystem studied, the first essential study concerned the identification of VOC-emitting species. This was done with the aid of a flux footprint model combined with a map of the species occurring on the site. This analysis showed that the main monoterpene emitter was Fagus sylvatica followed, to a lesser extent, by Abies alba, Picea Abies and Pseudotsuga menziessi. In contrast to the literature, the analysis showed Abies alba to be a probable isoprene emitter but the presence of Picea Abies, a known isoprene emitter, ruled out absolute certainty on that point. The isoprene fluxes were observed by day only, unlike the monoterpene fluxes which were observed both day and night. Diurnal flux analysis clearly showed temperature and light to be the two main variables controlling emissions. Combining this analysis with a study of the close relationship between isoprene/monoterpene emissions and photosynthesis revealed the plants’ de novo biosynthetic production mechanisms, an original aspect at ecosystem scale. From the occurrence of nocturnal monoterpene emissions it was possible to determine that de novo monoterpene production emitted directly into the atmosphere (as in the case of isoprene) was not the only source of the emissions observed. Withdrawals from monoterpene sinks located in plant organs or in the soil can also be monoterpene sources. Studying the relationship between isoprene/monoterpene fluxes and light, distinguishing between cloudy and sunny conditions, showed that for the same light intensity the emissions were higher in cloudy con-ditions than in sunshine. Similarly, a study of the relationship between isoprene fluxes and photosynthesis in cloudy/sunny conditions suggested that de novo isoprene production is greater in leaves above the canopy than in leaves within the canopy. Long-term measurement of isoprene and monoterpene emissions enabled seasonal changes in the mechanisms observed to be studied and more fully understood. As well as providing an understanding of the mechanisms, this research also resulted in quantification of the seasonal changes in the key parameters for modelling isoprene/monoterpene emissions. Methanol exchanges were generally positive (emissions) by day and negative (depositions) at night. Overall, methanol depositions were predominant in summer and autumn but in the mi-nority in spring. On average, the Vielsalm site behaved like a methanol sink, which contradicts all the other research published to date. An original model was developed for identifying the mechanisms responsible for short-term and long-term methanol emissions/depositions. The consistency between the measurements and the model simulations suggested that the main processes controlling methanol exchanges in summer could be attributed, in the short term, to (water-soluble) methanol adsorption/desorption occurring in the films of water on leaf surfaces and/or on the soil surface and, in the long term, to methanol destruction by a biological and/or chemical degradation process also occurring on the surface of leaves and/or the soil. A study of the difference between the measurements and the model, in spring, indicated the possibility of biosynthetic methanol production by the plants. This production was apparently controlled mainly by temperature, but it could not be shown in summer when methanol adsorption/desorption processes dominated. The literature on ecosystem-atmosphere exchanges of isoprene, monoterpenes and, to a lesser extent, methanol is extensive. Nevertheless, what makes this research original is the spatio-temporal scale used. We are in fact working at ecosystem scale, and not at leaf or branch scale as in most other cases. Moreover, our measurements cover a timescale from half an hour to a full growing season, which is rarely found in the literature. This has resulted in a better under-standing of these compounds’ production and exchange mechanisms. To be precise, the methanol flux study is currently unique in its description and understanding of the deposition mechanisms. [less ▲]

Detailed reference viewed: 195 (15 ULg)
Full Text
See detailLong-term study of methane and two of its derivatives from solar observations recorded at the Jungfraujoch station
Bader, Whitney ULg

Doctoral thesis (2015)

A long-term study of methane and two of its derivatives, i.e. ethane and methanol from ground-based FTIR solar observations recorded at the high alpine International Scientific Station of the Jungfraujoch ... [more ▼]

A long-term study of methane and two of its derivatives, i.e. ethane and methanol from ground-based FTIR solar observations recorded at the high alpine International Scientific Station of the Jungfraujoch (3580 m a.s.l.) is reported. Those three gases act as tropospheric ozone precursors through their removal pathway and therefore have an impact on air quality. In the stratosphere, methane influences the content of ozone and in the production of water vapor. Moreover, both methane and ethane impact the greenhouse radiative forcing. While the latter is an indirect greenhouse gas because of its sinks, the former is the second most important anthropogenic greenhouse gas after CO2. The primary challenge of this work is the development and optimization of retrieval strategies for the three studied gases from FTIR spectra recorded at the Jungfraujoch station, in the framework of the Network for Detection of Atmospheric Composition Change (NDACC), in order to assess their concentrations in the atmosphere and to study their long-term trend and recent changes as well as their seasonal variations. The development and optimization of a retrieval strategy, based on the selection of the best combination of parameters, aims to limit interferences, minimize residuals, and maximize information content. To this end, the best retrieval strategy has been selected from a great number of available combinations thanks to a method for error analysis developed through this work. A 17-year time series of methanol is presented thanks to the combination of spectral windows for the first time for ground-based observations resulting in the improvement of the information content. We therefore present the first long-term time series of methanol total, lower tropospheric and upper tropospheric–lower stratospheric partial columns. We found no significant long-term trend of methanol but its seasonal cycle shows a high peak-to-peak amplitude of ̴103 % for total columns characterized by minimum values in winter and maximum values during summertime. The presented time series provides a valuable tool for model and satellite validation and complement the few NDACC measurements at northern mid-latitudes. Regarding ethane, we have for the first time included a combination of improved spectroscopic parameters as well as an improved a priori state that substantially reduce fitting residuals and enhance information content. Analysis of the long-term trend of ethane covering 20 years of observations revealed a strong positive trend of ethane from 2009 onwards of ̴5 %/year. We hypothesize that this recent ethane upturn may be the result of a large increase in fugitive emissions from the massive exploitation of shale gas and tight oil reservoirs on the North American continent. Finally, we quantified the changes of methane since 2005 from 10 ground-based NDACC sites, with a mean global increase of 0.30 %/year. Investigations into the source(s) responsible for this re-increase are performed with a GEOS-Chem tagged simulation that provides the contribution of each emission source and one sink to the total methane simulated. From the analysis of the GEOS-Chem tracers on both the local and global scales, we determined that the increasing anthropogenic emissions such as coal mining, gas and oil transport and exploitation, have played a major role in the increase of atmospheric methane observed since 2005 while they are secondary contributors to the total methane budget. [less ▲]

Detailed reference viewed: 118 (19 ULg)
Full Text
Peer Reviewed
See detailLong-term treatment of postmenopausal osteoporosis with strontium ranelate: Results at 8 years.
Reginster, Jean-Yves ULg; Bruyère, Olivier ULg; Sawicki, A. et al

in BONE (2009), 45

OBJECTIVES: Strontium ranelate 2 g/day has proven efficacy against vertebral and nonvertebral fracture over 5 years in postmenopausal osteoporosis, though many women require longer-term treatment. This ... [more ▼]

OBJECTIVES: Strontium ranelate 2 g/day has proven efficacy against vertebral and nonvertebral fracture over 5 years in postmenopausal osteoporosis, though many women require longer-term treatment. This article describes the efficacy, safety, and tolerability of this agent over 8 years. METHODS: Postmenopausal osteoporotic women having participated in the 5-year efficacy trials SOTI and TROPOS were invited to enter a 3-year open-label extension study. The results presented here focus on patients who received strontium ranelate for 8 years. RESULTS: At the extension baseline, the population treated for 8 years (n=879; 79.1+/-5.6 years) had femoral neck T-score of -2.61+/-0.71. The cumulative incidences of new vertebral and nonvertebral fractures (13.7% and 12.0%, respectively) over years 6 to 8 were non-statistically different from the cumulative incidences in the first 3 years of the original studies (11.5% and 9.6%). Lumbar spine, femoral neck, and total hip bone mineral density (BMD) increased throughout the 8-year period. Annual relative change in BMD was significant at every visit, except the 8-year visit for femoral neck and total hip BMD. Strontium ranelate was safe and well tolerated over 8 years. CONCLUSIONS: Long-term treatment with strontium ranelate 2 g/day in postmenopausal osteoporotic women leads to continued increases in BMD at all sites. The data also provide some evidence for a sustained antifracture efficacy. [less ▲]

Detailed reference viewed: 97 (31 ULg)
Full Text
Peer Reviewed
See detailLong-term treatment of postmenopausal osteoporotic women with strontium ranelate : results at 10 years
Reginster, Jean-Yves ULg; Kaufman, J. M.; Devogelaer, J. D. et al

in Annals of the Rheumatic Diseases (2011), 70(S3), 167

Detailed reference viewed: 32 (8 ULg)
Full Text
Peer Reviewed
See detailLong-term treatment with valproic acid does not alleviate the condition of HAM/TSP
Olindo, S.; Belrose, G.; Lezin, A. et al

in AIDS Research and Human Retroviruses (2009, July 01), 25(11), 21

Long-Term Treatment with Valproic Acid Does Not Alleviate the Condition of HAM/TSP Olindo, S.,1 Belrose, G.,2 Lezin, A.,2 Gillet, N.,3 Defoiche, J.,4 Rodriguez, S.,4 Signaté, A.,1 Verlaeten, O.,4 Smadja ... [more ▼]

Long-Term Treatment with Valproic Acid Does Not Alleviate the Condition of HAM/TSP Olindo, S.,1 Belrose, G.,2 Lezin, A.,2 Gillet, N.,3 Defoiche, J.,4 Rodriguez, S.,4 Signaté, A.,1 Verlaeten, O.,4 Smadja, D.,1 Césaire, R.,2 Willems, L.4 1Service de Neurologie and JE 2503, Centre Hospitalier Universitaire de Fort-de-France, 97200 Fort-de-France, Martinique, France; 2Laboratoire de Virologie-Immunologie and JE 2503, Centre Hospitalier Universitaire de Fort-de-France, 97200 Fort-de-France, Martinique, France; 3Department of Immunology, Imperial College, London, UK; 4Molecular and Cellular Biology, University Academia ‘‘Wallonie-Europe’’, 5030 Gembloux, Belgium. LW is Research Director of the FNRS. We previously proposed to interfere with proviral loads in HAM/TSP patients by modulating lysine deacetylase activity using valproic acid (VPA). The strategy aims at activating viral gene expression in order to expose virus-positive cells to the host immune response. We conducted a single-center, two-year open-label trial, with 19 HAM/TSP volunteers treated with oral doses of VPA (20mg/Kg/day). Objectives were to assess biological response and clinical safety to VPA treatment in HAM/TSP patients. By microarray analysis, we show that VPA treatment moderately stimulated expression of cyclinD2 and Rho GTPase activating protein 18 in CD4-T cells. CD8-mediated lysis efficiency of Tax-expressing cells was unaltered by VPA treatment. The CD4-T cell turnover rate was calculated by GC/MS analysis from quantitative incorporation of deuterium into DNA. Transient increase in proviral loads correlated with accelerated proliferation. After 2 years, the proviral loads reached levels similar to those before treatment. The main clinical side effects were drowsiness (52%), tremor (47%), digestive symptoms (37%), vertigo (26%), and alopecia (10%). The frequency of side symptoms tended to decrease over the trial course. The neurological status over the study constituted the primary clinical safety measures. Disability Status Scale, muscle testing score, Ashworth score, and urinary dysfunction score showed no significant changes. Walking Time Test (WTT) slightly varied over the study except in 3 patients in whom the WTT variation rates were>20%. These 3 patients experienced drowsiness and tremor and improved rapidly after treatment discontinuation. Together, these observations indicated that long term treatment with VPA is safe but does not alleviate the condition of HAM/TSP. [less ▲]

Detailed reference viewed: 193 (1 ULg)
Full Text
See detailLong-term trend of carbon tetrachloride (CCl4) from ground-based high resolution infrared solar spectra recorded at the Jungfraujoch
Rinsland, Curtis P.; Mahieu, Emmanuel ULg; Demoulin, Philippe ULg et al

in Geophysical Research Abstracts (2010), 12(EGU2010-1819-3),

The long-term trend of carbon tetrachloride (CCl4) has been retrieved from infrared high resolution solar absorption spectra encompassing the 1999 to 2010 time period. The measurements were recorded with ... [more ▼]

The long-term trend of carbon tetrachloride (CCl4) has been retrieved from infrared high resolution solar absorption spectra encompassing the 1999 to 2010 time period. The measurements were recorded with a Fourier transform spectrometer at the northern mid-latitude, high altitude Jungfraujoch station in Switzerland (46.5°N latitude, 8.0°E longitude, 3580 m altitude). Total columns were derived from the region of the strong CCl4 _3 band at 794 cm􀀀1 accounting for all interfering molecules (e.g. H2O, O3) with significant improvement in the residuals obtained by also taking into account the line mixing in a nearby CO2 Q branch, a procedure not implemented in previous remote sensing CCl4 retrievals though its importance has been noted in several papers. The time series shows a statistically-significant long-term decrease in the CCl4 total atmospheric burden of -1.18_0.10 %/yr, at the 95% confidence level, using 2005 as reference. Furthermore, fit to the total column data set also reveals a seasonal cycle with a peak-to-peak amplitude of 10.2%, with minimum and maximum values found in mid-February and early August, respectively. This seasonal modulation can however be attributed to tropopause height changes throughout the season. The results quantify the continued impact of the regulations implemented by the Montreal Protocol and its strengthening amendments and adjustments for a molecule with high global warming potential. Although a statistically significant decrease in the total column is inferred, the CCl4 molecule remains an important contributor to the stratospheric chlorine budget and burden. [less ▲]

Detailed reference viewed: 69 (6 ULg)
Full Text
Peer Reviewed
See detailLong-term trend of CH4 at northern mid-latitudes: Comparison between ground-based infrared solar and surface sampling measurements
Rinsland, Curtis P.; Goldman, Aaron; Elkins, James W. et al

in Journal of Quantitative Spectroscopy & Radiative Transfer (2006), 97(3), 457-466

We report average tropospheric CH4 volume mixing ratios retrieved from a 27 year time series of high spectral resolution infrared solar absorption measurements recorded between May 1977 and July 2004 at ... [more ▼]

We report average tropospheric CH4 volume mixing ratios retrieved from a 27 year time series of high spectral resolution infrared solar absorption measurements recorded between May 1977 and July 2004 at the US National Solar Observatory station on Kitt Peak (31.9 degrees N, 111.6 degrees W, 2.09 km altitude) and their comparison with surface in situ sampling measurements recorded between 1983 and 2004 at the Climate Monitoring and Diagnostics Laboratory (CMDL) station at Niwot Ridge, Colorado (40.0 degrees N, 105.5 degrees W, 3013 m altitude). The two measurement sets therefore overlap for the 1983-2004 time period. An average tropospheric volume mixing ratios of 1814 +/- 48 ppbv (1 ppbv = 10(-9) per unit volume) has been derived from the solar absorption time series with a best-fit increase rate trend equal to 8.26 +/- 2.20 ppbv yr(-1) in 1983 decreasing to 1.94 +/- 3.69 ppbv yr(-1) in 2003. The CMDL measurements also show a continuous long-term CH4 volume mixing ratio rise, with subsequent slowing down. A mean ratio of the retrieved average tropospheric volume mixing ratio to the CMDL volume mixing ratio for the overlapping time period of 1.038 +/- 0.034 indicates agreement between both data sets within the quantified experimental errors. (C) 2005 Elsevier Ltd. All rights reserved. [less ▲]

Detailed reference viewed: 32 (3 ULg)
Full Text
See detailLong-term trends of a dozen direct greenhouse gases derived from infrared solar absorption spectra recorded at the Jungfraujoch station
Mahieu, Emmanuel ULg; Duchatelet, Pierre; Zander, Rodolphe ULg et al

Poster (2011, November 10)

References Bader, W. et al., Extension of the long-term total column time series of atmospheric methane above the Jungfraujoch station: analysis of grating infrared spectra between 1976 and 1989 ... [more ▼]

References Bader, W. et al., Extension of the long-term total column time series of atmospheric methane above the Jungfraujoch station: analysis of grating infrared spectra between 1976 and 1989, Geophysical Research Abstracts, 13, EGU2011-3391-1, 2011. [http://hdl.handle.net/2268/88180] Duchatelet, P. et al., First retrievals of carbon tetrafluoride (CF4) from ground-based FTIR measurements: production and analysis of the two-decadal time series above the Jungfraujoch, Geophysical Research Abstracts, 13, EGU2011-6413, 2011. [http://hdl.handle.net/2268/90745] Gardiner, T. et al., Trend analysis of greenhouse gases over Europe measured by a network of ground-based remote FTIR instruments, Atmos. Chem. Phys., 8, 6719-6727, 2008. [http://hdl.handle.net/2268/2545] Rodgers, C.D., Characterisation and error analysis of profiles derived from remote sensing measurements, J. Geophys. Res., 95, 5587-5595, 1990. Zander, R. et al., Our changing atmosphere: Evidence based on long-term infrared solar observations at the Jungfraujoch since 1950, Sci. Total Environ., 391, 184-195, 2008. [http://hdl.handle.net/2268/2421] [less ▲]

Detailed reference viewed: 495 (36 ULg)
Full Text
Peer Reviewed
See detailLong-term trends of inorganic chlorine from ground-based infrared solar spectra: Past increases and evidence for stabilization
Rinsland, Curtis P.; Mahieu, Emmanuel ULg; Zander, Rodolphe ULg et al

in Journal of Geophysical Research (2003), 108(D8), 4252

Long-term time series of hydrogen chloride (HCl) and chlorine nitrate (ClONO2) total column abundances has been retrieved from high spectral resolution ground-based solar absorption spectra recorded with ... [more ▼]

Long-term time series of hydrogen chloride (HCl) and chlorine nitrate (ClONO2) total column abundances has been retrieved from high spectral resolution ground-based solar absorption spectra recorded with infrared Fourier transform spectrometers at nine NDSC (Network for the Detection of Stratospheric Change) sites in both Northern and Southern Hemispheres. The data sets span up to 24 years and most extend until the end of 2001. The time series of Cly (defined here as the sum of the HCl and ClONO2 columns) from the three locations with the longest time-span records show rapid increases until the early 1990s superimposed on marked day-to-day, seasonal and inter-annual variability. Subsequently, the buildup in Cly slows and reaches a broad plateau after 1996, also characterized by variability. A similar time evolution is also found in the total chlorine concentration at 55 km altitude derived from Halogen Occultation Experiment (HALOE) global observations since 1991. The stabilization of inorganic chlorine observed in both the total columns and at 55 km altitude indicates that the near-global 1993 organic chlorine (CCly) peak at the Earth’s surface has now propagated over a broad altitude range in the upper atmosphere, though the time lag is difficult to quantify precisely from the current data sets, due to variability. We compare the three longest measured time series with two-dimensional model calculations extending from 1977 to 2010, based on a halocarbon scenario that assumes past measured trends and a realistic extrapolation into the future. The model predicts broad Cly maxima consistent with the long-term observations, followed by a slow Cly decline reaching 12–14% relative to the peak by 2010. The data reported here confirm the effectiveness of the Montreal Protocol and its Amendments and Adjustments in progressively phasing out the major man-related perturbations of the stratospheric ozone layer, in particular, the anthropogenic chlorine-bearing source gases. [less ▲]

Detailed reference viewed: 29 (12 ULg)
Full Text
See detailLong-term trends of NO above northern mid-latitudes as inferred from Jungfraujoch, HALOE and ACE-FTS solar observations
Demoulin, Philippe ULg; Mahieu, Emmanuel ULg; Servais, Christian ULg et al

Poster (2012, August 27)

Routine FTIR solar observations are performed by the University of Liège at the Jungfraujoch station (Swiss Alps, 3580 m altitude, NDACC station) since 1985. The analysis of the recorded spectra allows to ... [more ▼]

Routine FTIR solar observations are performed by the University of Liège at the Jungfraujoch station (Swiss Alps, 3580 m altitude, NDACC station) since 1985. The analysis of the recorded spectra allows to derive total and partial columns of more than 20 different atmospheric gases. Among them, gases belonging to the total reactive nitrogen NOy (NO, NO2, HNO3 and ClONO2), to the total inorganic chlorine Cly (HCl and ClONO2) and to the total inorganic fluorine Fy (HF and COF2) families. In this communication, budgets of these gas families are investigated, and their short term, seasonal and inter-annual variations as well as their long-term trends are determined for the time period ranging from the mid-1980s up to the end of 2011. We also investigate the evolution of the same gases, when available, derived from ground-based UV-vis (1990-present) and from HALOE (1991-2004) and ACE-FTS (2004-present) satellite observations. We evaluate the consistency between the trends characterizing these various species, as deduced from the ground- and space-based time series. [less ▲]

Detailed reference viewed: 21 (4 ULg)
Full Text
Peer Reviewed
See detailLong-term trends of tropospheric carbon monoxide and hydrogen cyanide from analysis of high resolution infrared solar spectra
Rinsland, Curtis P.; Goldman, Aaron; Hannigan, James W. et al

in Journal of Quantitative Spectroscopy & Radiative Transfer (2007), 104(1), 40-51

Long-term trend and seasonal variation of the mean free tropospheric volume mixing ratios of carbon monoxide (CO) and hydrogen cyanide (HCN) have been derived from analysis of a time series of solar ... [more ▼]

Long-term trend and seasonal variation of the mean free tropospheric volume mixing ratios of carbon monoxide (CO) and hydrogen cyanide (HCN) have been derived from analysis of a time series of solar absorption spectra recorded from the US National Solar Observatory on Kitt Peak (31.9 degrees N, 111.6 degrees W, 2.09 km altitude) spanning almost three decades. The results of a fit to the CO 258 daily averages from May 1977 to April 2005 as a function of time with a model that assumes a sinusoidal seasonal cycle and a linear long-term trend with time yield a mean volume mixing ratio of 102 +/- 3) parts per billion (10(-9) per unit volume) below 10km altitude, I sigma. The CO measurements show a seasonal cycle with a maximum in March and a minimum in September with an amplitude of (22.3 +/- 1.5)% relative to the mean. The best-fit corresponds to a long-term CO trend of (0.15 +/- 0.14)% yr(-1), 1 sigma, relative to the mean. To quantify the possible impact of periods of intense fires, the CO measurements have been compared with the measurements of HCN, a well-documented emission product of biomass burning with a lifetime of similar to 5 months. The best fit to the full HCN time series of 208 daily averages from May 1978 to April 2005 results in a mean volume mixing ratio of (0.219 +/- 0.007) ppbv below 10 km altitude with a similar seasonal cycle, though with a lower relative amplitude than for CO. Although same-day enhancements up to a factor of 1.87 for HCN and 1.24 for CO were measured relative to values predicted by a fit to the time series that accounts for the seasonal cycles and trends of both molecules, excluding time periods of elevated fire emissions has no significant impact on the best-fit long-term free tropospheric CO and HCN trends. Our result of no long-term CO trend since the late 1970s suggests that the global average long-term decline reported from 1990 through 1995 measurements has not continued in the free troposphere. Similarly, a fit to the full time series of 208 HCN free tropospheric daily averages with the same model yields an average 2.09-10km mixing ratio of 0.219ppbv and a long-term trend of (-0.12 +/- 0.14) % yr(-1), 1 sigma, relative to the mean since 1978, also indicating no significant long-term trend above the lower mid-latitude continental US Kitt Peak station. The results for both molecules suggest the site was not significantly impacted by summer boreal fires during the time span of the measurements that in some years cause widespread pollution above northern higher latitude sites. (c) 2006 Elsevier Ltd. All rights reserved. [less ▲]

Detailed reference viewed: 48 (9 ULg)
See detailLong-term variation of the standing crop and other biometric aspects of Posidonia oceanica in Calvi Bay
Gobert, Sylvie ULg; Belkhiria, Samy; Soullard, Mady et al

Conference (1993, January)

Detailed reference viewed: 21 (1 ULg)
Full Text
Peer Reviewed
See detailLong-term XMM-Newton investigation of two particle-accelerating colliding-wind binaries in NGC6604: HD168112 and HD167971
De Becker, Michaël ULg

in Monthly Notices of the Royal Astronomical Society (2015), 451(1), 5589-5599

The long-term (over more than one decade) X-ray emission from two massive stellar systems known to be particle accelerators is investigated using XMM-Newton. Their X-ray properties are interpreted taking ... [more ▼]

The long-term (over more than one decade) X-ray emission from two massive stellar systems known to be particle accelerators is investigated using XMM-Newton. Their X-ray properties are interpreted taking into account recent information about their multiplicity and orbital parameters. The two targets, HD168112 and HD167971 appear to be overluminous in X-rays, lending additional support to the idea that a significant contribution of the X-ray emission comes from colliding-wind regions. The variability of the X-ray flux from HD168112 is interpreted in terms of varying separation expected to follow the 1/D rule for adiabatic shocked winds. For HD167971, marginal decrease of the X-ray flux in September 2002 could tentatively be explained by a partial wind eclipse in the close pair. No long-term variability could be demonstrated despite the significant difference of separation between 2002 and 2014. This suggests the colliding-wind region in the wide orbit does not contribute a lot to the total X-ray emission, with a main contribution coming from the radiative shocked winds in the eclipsing pair. The later result provides evidence that shocks in a colliding-wind region may be efficient particle accelerators even in the absence of bright X-ray emission, suggesting particle acceleration may operate in a wide range of conditions. Finally, in hierarchical triple O-type systems, thermal X-rays do not necessarily constitute an efficient tracer to detect the wind-wind interaction in the long period orbit. [less ▲]

Detailed reference viewed: 54 (6 ULg)
Full Text
Peer Reviewed
See detailA long-term, open-label trial of the safety and efficacy of etanercept (Enbrel) in patients with rheumatoid arthritis not treated with other disease-modifying antirheumatic drugs
Klareskog, L.; Gaubitz, M.; Rodriguez-Valverde, V. et al

in Annals of the Rheumatic Diseases (2006), 65(12), 1578-1584

Objective: To evaluate the long-term safety and efficacy of etanercept in patients with rheumatoid arthritis. Methods: 549 patients entered this 5-year, open-label extension study and received etanercept ... [more ▼]

Objective: To evaluate the long-term safety and efficacy of etanercept in patients with rheumatoid arthritis. Methods: 549 patients entered this 5-year, open-label extension study and received etanercept 25 mg twice weekly. All patients showed inadequate responses to disease-modifying antirheumatic drugs before entry into the double-blind studies. Safety assessments were carried out at regular intervals. Primary efficacy end points were the numbers of painful and swollen joints; secondary variables included American College of Rheumatology (ACR) response rate, Disease Activity Score and acute-phase reactants. Efficacy was analysed using the last-observation-carried-forward approach. Results: Of the 549 patients enrolled in the open-label trial, 467 (85%), 414 (75%) and 371 (68%) completed 1, 2 and 3 years, respectively; 363 (66%) remained in the study at the time of this analysis. A total exposure of 1498 patient-years, including the double-blind study, was accrued. In the open-label trial, withdrawals for efficacy-related and safety-related reasons were 11% and 13%, respectively. Frequent adverse events included upper respiratory infections, flu syndrome, rash and injection-site reactions. Rates of serious infections and malignancies remained unchanged over the course of the study; there were no reports of patients with central demyelinating disease or serious blood dyscrasias. After 3 years, ACR20, ACR50 and ACR70 response rates were 78%, 51% and 27%, respectively. The Disease Activity Score score was reduced to 3.0 at 3 months and 2.6 at 3 years from 5.1. A sustained improvement was found in Health Assessment Questionnaire scores throughout the 3-year time period. Conclusion: After 3 years of treatment, etanercept showed sustained efficacy and a favourable safety profile. [less ▲]

Detailed reference viewed: 30 (1 ULg)