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See detailImpact of different spectroscopic datasets on CH4 retrievals from Jungfraujoch FTIR spectra
Duchatelet, Pierre ULg; Mahieu, Emmanuel ULg; Demoulin, Philippe ULg et al

Poster (2008, August)

Methane (CH4) is released in the atmosphere by natural processes (e.g. wetlands, termites) as well as by anthropogenic activities (e.g. fossil fuel exploitation, rice agriculture, biomass burning, etc ... [more ▼]

Methane (CH4) is released in the atmosphere by natural processes (e.g. wetlands, termites) as well as by anthropogenic activities (e.g. fossil fuel exploitation, rice agriculture, biomass burning, etc). Due to its high warming potential and its relatively long chemical lifetime (~9 years), atmospheric methane plays a major role in the radiative forcing responsible of the greenhouse effect. Methane also affects climate by influencing tropospheric ozone and stratospheric water. The cycle of methane is complex and to understand it requires a complete study of its emissions and its budget of sources and sinks. High quality methane data sets are needed to perform such studies. CH4 vertical distributions as well as total and partial column time series can be retrieved from high-resolution ground-based FTIR spectra, using, e.g., the SFIT-2 algorithm which implements the Optimal Estimation Method of Rodgers. A set of 5 microwindows - located in the 2 to 5.5 µm range and jointly adopted by all partners involved in the European HYMN project (www.knmi.nl/samenw/hymn/) - are fitted simultaneously during the retrieval procedure. Although this approach provides relatively high information content, CH4 retrieved profiles very often present large oscillations in the troposphere, which might result partly from inappropriate or inconsistent spectroscopic parameters. Significant improvements on retrieval quality could be reached by using more accurate CH4 spectroscopic parameters. This contribution compares 3 different sets of CH4 spectroscopic parameters (including HITRAN 2004 and 2 versions where HITRAN 2004 have been updated by recent laboratory measurements), which have been tested using one year of high resolution FTIR solar observations performed at the International Scientific Station of the Jungfraujoch (Swiss Alps, 46.5°N, 8.0 °E, 3580m a.s.l.). The impact of these different spectroscopic datasets on retrieved CH4 partial columns and vertical profiles, as well as on the fitting quality (residuals) and on the error budget characterizing our CH4 products will be evaluated and discussed. [less ▲]

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See detailImpact of different spectroscopic datasets on CH4 retrievals from Jungfraujoch FTIR spectra
Duchatelet, Pierre ULg; Mahieu, Emmanuel ULg; Demoulin, Philippe ULg et al

(2008)

Due to its high warming potential and its relatively long chemical lifetime (~9 years), atmospheric methane (CH4) plays a major role in the radiative forcing responsible of the greenhouse effect. Methane ... [more ▼]

Due to its high warming potential and its relatively long chemical lifetime (~9 years), atmospheric methane (CH4) plays a major role in the radiative forcing responsible of the greenhouse effect. Methane also affects climate by influencing tropospheric ozone and stratospheric water. High quality methane data sets are needed to understand its cycle and evaluate its budget of sources and sinks. Methane vertical distribution as well as total and partial column time series can be retrieved from high-resolution ground-based FTIR spectra, using, e.g., the SFIT-2 algorithm which implements the Optimal Estimation Method of Rodgers . However, although several retrieval approaches characterized by relatively high information content exist, methane retrieved profiles very often present large oscillations in their tropospheric range, which might result partly from inappropriate or inconsistent parameters. Significant improvements on retrieval quality should therefore be reached by using more accurate or compatible CH4 spectroscopic data. The main purpose of this contribution is to test and compare three different sets of CH4 spectroscopic parameters and to quantify their impact on CH4 retrieved products as well as on the fitting quality. [less ▲]

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See detailImpact of diffuse light on isoprene and monoterpene emissions from a mixed temperate forest
Laffineur, Quentin ULg; Aubinet, Marc ULg; Schoon, Niels et al

in Atmospheric Environment (2013), 46(74), 385-392

This study investigated the impact of diffuse light on canopy scale emission of isoprene and monoterpenes measured continuously above a mixed temperate forest, using the disjunct eddy-covariance by mass ... [more ▼]

This study investigated the impact of diffuse light on canopy scale emission of isoprene and monoterpenes measured continuously above a mixed temperate forest, using the disjunct eddy-covariance by mass scanning technique with a proton transfer reaction-mass spectrometer (PTR-MS) instrument. To assess this impact, the relationship between emissions/radiation and emissions/gross primary production (GPP) under clear sky and cloudy conditions were analysed. Under cloudy conditions (high proportion of diffuse radiation), the isoprene and monoterpene fluxes were enhanced compared to clear sky conditions (low proportion of diffuse radiation) at equivalent temperature and above-canopy total radiation. The whole-canopy enzymatic activity of the metabolic isoprene production pathway, however, was suggested to be lower under cloudy conditions than under clear sky conditions at equivalent temperature. The mechanisms behind these observations are probably linked to the better penetration of diffuse radiation in the canopy. Shade leaves/needles receive more radiation in cloudy conditions than in clear sky conditions, thereby inducing the observed effects. [less ▲]

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See detailThe impact of disease on pregnancy: monitoring of fetal viability and choice of approach in delivery
Foidart, Jean-Michel ULg

in Revue Médicale de Liège (1988), 43(22), 745-8

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See detailImpact of dolomite lime on the ground vegetation and on potential net N transformations in Norway spruce (Picea Abies (L.) Karst.) and sessile oak (Quercus Petraea (Matt.) Lieb.) stands in the Belgian Ardenne
Duliere, J.-F.; Carnol, Monique ULg; Dalem, S. et al

in Annals of Forest Science : a Multidisciplinary and International Journal (1999), 56

The impact of dolomite lime (5 T·ha-1) on the ground vegetation and on potential net nitrogen (N) transformations was investigated in two Belgian forest ecosystems. Norway spruce (Picea abies (L.) Karst ... [more ▼]

The impact of dolomite lime (5 T·ha-1) on the ground vegetation and on potential net nitrogen (N) transformations was investigated in two Belgian forest ecosystems. Norway spruce (Picea abies (L.) Karst.) and sessile oak (Quercus petraea (Matt.) Lieb.) stands were situated in the Haute Ardenne (east Belgium) on acid-brown soil. The herb-layer floristic richness increased during the 2 years following liming, with the appearance of light and N-demanding species, which are also found in clear-cut areas or on road verges. Mosses reacted rapidly, showing a decrease acidophilous-dominant species and the establishment of some ruderal species. Six months after liming, the pH was significantly increased in the organic horizon of both stands and in the organomineral horizon of the oak stand. Soils originating from the two stands showed distinct responses in net NO3- production to the dolomite lime treatment. In the organic layer of the Quercus soil, net NH4+ production was decreased, NO3- production increased, and total N mineralisation remained unchanged. In the organomineral layer, NO3 - production was increased. In the Picea soil, NO3 - production was decreased in the organomineral soil layer. These results indicate the possibility of differences in the control of the N transformation processes occurring in the two sites. [less ▲]

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See detailThe Impact of Dual-Tasking on Sentence Comprehension in Children with Specific Language Impairment
Leclercq, Anne-Lise ULg; Majerus, Steve ULg; Prigent, Gaïd ULg et al

in Journal of Speech, Language, and Hearing research (2013), 56

Purpose: This study assesses the hypothesis of a limitation in attentional allocation capacity as underlying poor sentence comprehension in children with SLI. Method: Fifteen children with SLI, 15 age ... [more ▼]

Purpose: This study assesses the hypothesis of a limitation in attentional allocation capacity as underlying poor sentence comprehension in children with SLI. Method: Fifteen children with SLI, 15 age-matched controls, and 15 grammar-matched controls. Sixty sentences were presented in isolation, and 60 sentences were presented with a concurrent non-linguistic target-detection task. If poor attentional allocation capacity is a core deficit in SLI, they should be impaired to a greater extent in the dual task condition relative to the grammatical-age controls. On the contrary, a comparable performance decrement under the dual-task condition in children with SLI and younger language controls would attest of a limitation in attentional allocation capacity in children with SLI that is not disproportionate to their language level. Results: Sentence comprehension was affected by the dual-task condition to a greater extent in children with SLI relative to age-controls, but not relative to grammatical-controls. Conclusions: Our study does not support limitations in attentional allocation capacity as representing a core deficit in SLI. Rather, our data show that these children show attentional allocation capacity comparable to that of younger children having similar language level, suggesting that SLI is characterized by a slowed development of both attentional and language domains. [less ▲]

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See detailThe Impact of Dual-Tasking on Verbal Short-Term Memory in Children with Specific Language Impairment
Leclercq, Anne-Lise ULg; Maillart, Christelle ULg; Lange, Manon et al

Poster (2014, June)

Limitations in general processing capacities have been proposed to account for poor verbal short-term memory (STM) performances in children with SLI. Previous studies observed that STM performances ... [more ▼]

Limitations in general processing capacities have been proposed to account for poor verbal short-term memory (STM) performances in children with SLI. Previous studies observed that STM performances decreased to a larger extent in children with SLI as compared to their unaffected peers when the processing demands of the task increased (e.g., Ellis Weismer, et al., 2005; Montgomery, 2000a,b). However, in these studies, the increase in attention processing demands went with an increase in linguistic processing demands. Since children with SLI experience language processing problems, it is not clear whether general attention problems or language processing problems are at the root of their larger performance decrease as compared to their unaffected peers. This study aims at directly assessing the hypothesis that limitations in general attentional capacity are at the root of poor STM performances in children with SLI, using an attention demanding visual search task administered concurrently with nonword repetition task. Twenty-three children with SLI, 23 age-matched children, and 23 nonword span-matched children performed immediate serial recall tasks of nonwords. The STM lists were presented either alone or concurrently with the target detection task. Moreover, the target detection task either stopped or continued when children had to recall the nonwords. Results show a main effect of dual task condition on both nonword repetition accuracy and target detection accuracy. Performances in children with SLI were not more affected than in controls by the necessity to perform a concurrent visual attention task during nonword lists presentation. However, nonword recall seemed to be more challenging for children with SLI than for age-matched controls. Indeed, performances in the visual task were lower in children with SLI than in their age-matched controls, but not as compared to nonword span-matched controls. [less ▲]

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See detailImpact of dust processes on air quality in Niamey, Niger, and consequences on human health
Ozer, Pierre ULg

in Gabriels, Donald; Cornelis, Wim M.; Eyletters, Murielle (Eds.) et al Combating desertification: Assessment, adaptation and mitigation strategies (2008)

It is now irrefutable that air pollution caused by large amounts of respiratory particulates (Particulate Matter less than 10 µm in aerodynamic diameter, PM10) has numerous undesired consequences on human ... [more ▼]

It is now irrefutable that air pollution caused by large amounts of respiratory particulates (Particulate Matter less than 10 µm in aerodynamic diameter, PM10) has numerous undesired consequences on human health. Although air quality degradation far away from the African continent in the US and in Europe caused by high concentration of African dust is seen as a major health threat although most of these countries are very distant from the Sahara; no estimates of PM10 levels near the Saharan dust source are available. Based on horizontal visibility observations which are reduced by the presence of dust in the atmosphere, PM10 levels are estimated during 2005 at Niamey-Airport, Niger. It appears that excessive concentrations of particles are very important both in magnitude and frequency as the 24-hour PM10 thresholds established by the US EPA National Ambient Air Quality Standards and the EU Limits Values for Air Quality were exceeded 103 and 67 times, respectively. The average yearly concentration is far above air quality standards and estimated to 92 µg m-3 for PM10. These very high particulate levels are likely to represent an important public health threat and should be considered as a major environmental risk. [less ▲]

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See detailImpact of early versus late acquired blindness on the fuctional organization and connectivity of the occipital cortex
Collignon, O; Phillips, C; Dormal, G et al

Poster (2012, May)

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See detailImpact of elevated pCO2 on optical properties of the coccolithophorid Emiliania huxleyi grown under nitrate limitation
Denis, Michel; Sciandra, Antoine; Harlay, Jérôme ULg et al

Conference (2003, April 06)

Side scatter and red fluorescence properties of the coccolithophore Emiliania huxleyi were investigated when NO3-limited continuous cultures were submitted to a CO2 partial pressure (pCO2) increase from ... [more ▼]

Side scatter and red fluorescence properties of the coccolithophore Emiliania huxleyi were investigated when NO3-limited continuous cultures were submitted to a CO2 partial pressure (pCO2) increase from 400 to 700 ppm. Cultures renewed at the rate of 0.5 d-1 and were submitted to saturating light level. pCO2 was controlled by bubbling CO2-rich or CO2- free air in the cultures. Side scatter of a single cell is considered to reflect not only its overall shape but mainly its inner structure and content through a complex combination of optical properties including absorption, diffusion, refractive index and refraction. Consequently, the cultures of Emiliania huxleyi were monitored by flow cytometry to detect possible changes in its optical properties at the single cell level under the effect of CO2 doubling in the atmospheric phase. The average SD for counting 5 replicates was less than 1.6% over the period of the study. It was 0.1 and 0.2% for fluorescence and side scatter respectively. Considering the possible decalcification induced by the increase of CO2 in the chemostat atmosphere, the maximum variation that can be expected for side scatter is that provided by the coccolith depletion upon acidification of the cell suspension. The acidification induced a large (36%) decrease of the side scatter signal as expected and had no detectable effect on the red fluorescence. To validate the assignment of this change on coccolith dissolution, the same experiment was repeated with a culture of a non-calcifying species, Dunaliella tertiolecta. The acidification of D. tertiolecta suspension induced no detectable change, both on fluorescence and side scatter. During the time of the experiment, the decline of side scatter never approached the potential 36% change observed when coccoliths are fully dissolved. Interestingly, the specific chl a fluorescence of E. huxleyi slightly increased during the period of high CO2 level. At the end of the experiment this increase amounted to 2.8% of the initial signal. The average SD of red fluorescence being 0.1%, this increase must be considered as significant. Furthermore, it progressed linearly with time over the period of observation. However, the experiment did not last enough to know if the fluorescence increase had already reached its maximum value. The acidification experiment supported the use of side scatter as a relevant parameter to trace potential changes in calcification. Since the estimated 25% decrease in calcification induced by the rise in CO2 atmosphere did not result in dramatic changes in side scatter values, we can conclude that the number of coccoliths and the overall shape and granulosity of cells was not significantly affected by this decrease. Changes must have only affected tiny structure details of the coccoliths like those observed on published electron micrographs. The small but significant increase of the fluorescence signal can be considered as a physiological response to the CO2 rise. This suggests a more dynamic photosynthetic process that would result in a higher rate of organic matter production providing that the system is not nutrient limited as in the present situation. [less ▲]

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See detailThe impact of enantioseparation techniques on the development and use of chiral drugs - Preface
Chankvetadze, B.; Crommen, Jacques ULg

in Journal of Pharmaceutical & Biomedical Analysis (2002), 27(3-4), 355-355

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See detailThe Impact of Energy on the Cost of Transport by Inland Waterways: a, Example of Bulk Transport
Marchal, Jean ULg; Planchar, R.; Potier, G.

in Proceedings of the "International Seminar on "Energy Efficiency in Land Transport", Luxembourg, Congrès sur invitation de la C.E.E (1988)

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See detailImpact of energy supply and oxygen transfer on selective lipopeptide production by Bacillus subtilis BBG21.
Fahim, Sameh; Dimitrov, Krasimir; Gancel, Frederique et al

in Bioresource technology (2012), 126

The influence of power dissipation and volumetric oxygen transfer coefficient k(L)a on Bacillus subtilis productivity of lipopeptides surfactin and fengycin was studied in shake flasks in view of scaling ... [more ▼]

The influence of power dissipation and volumetric oxygen transfer coefficient k(L)a on Bacillus subtilis productivity of lipopeptides surfactin and fengycin was studied in shake flasks in view of scaling-up of this fermentation process. The experiments performed with different flask sizes, relative filling volumes, and shaking frequencies confirmed clearly that lipopeptide production changed in function of power dissipation, via interfacial gas-liquid contact surface and oxygen supply. It was demonstrated that k(L)a is the key parameter controlling the productivity and the selectivity of the bioreaction. Varying the oxygen transfer conditions, the synthesis could be oriented to mixed production or to surfactin mono-production. The fraction of surfactin towards total lipopeptides produced and the maximal surfactin production both increased with k(L)a increase (surfactin concentration about 2 g L(-1) at k(L)a=0.04-0.08 s(-1)), while the maximal fengycin production (fengycin concentration about 0.3 g L(-1)) was obtained at moderate oxygen supply (k(L)a=0.01 s(-1)). [less ▲]

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See detailImpact of erythropoietic activity on red cell parameters in chronic renal failure patients.
Bovy, Christophe ULg; Krzesinski, Jean-Marie ULg; Gothot, André ULg et al

in Haematologica (2004), 89(6), 748-9

We measured red cell parameters during recombinant human erythropoietin (rHuEPO) therapy associated with appropriate iron supplementation in chronic hemodialysis patients. Increased erythropoietic ... [more ▼]

We measured red cell parameters during recombinant human erythropoietin (rHuEPO) therapy associated with appropriate iron supplementation in chronic hemodialysis patients. Increased erythropoietic activity led to a bias in red cell parameter determination. The percentage of hypochromic red blood cells, usually used as the most effective predictor of response to iron supplementation, increased following the appearance of a younger red cell population since the same Hb content in these younger, larger cells gives a lower Hb concentration. [less ▲]

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See detailImpact of exercise pulmonary hypertension on postoperative outcome in primary mitral regurgitation.
Magne, Julien; Donal, Erwan; Mahjoub, Haifa et al

in Heart (British Cardiac Society) (2014)

AIMS: The management of asymptomatic patients with mitral regurgitation (MR) remains controversial. Exercise-induced pulmonary hypertension (ExPHT) was recently reported as a strong predictor of rapid ... [more ▼]

AIMS: The management of asymptomatic patients with mitral regurgitation (MR) remains controversial. Exercise-induced pulmonary hypertension (ExPHT) was recently reported as a strong predictor of rapid onset of symptoms. We hypothesised that ExPHT is a predictor of postoperative cardiovascular events in patients with primary MR. METHODS AND RESULTS: One hundred and two patients with primary MR, no or mild symptoms (New York heart association (NYHA) </=2), and no LV dysfunction/dilatation, were prospectively recruited in 3 centres and underwent exercise-stress echocardiography. The presence of ExPHT was defined as an exercise systolic pulmonary arterial pressure >60 mm Hg. All patients were closely followed up and operated on when indication for surgery was reached. Postoperative events were defined as the occurrence of atrial fibrillation (AF), stroke, cardiac-related hospitalisation or death. Among the 102 patients included, 59 developed ExPHT (58%). These patients were significantly older than those without ExPHT (p=0.01). During a mean postoperative follow-up of 50+/-23 months, 28 patients (26%) experienced a predefined cardiovascular event. Patients with ExPHT had significantly higher rate of postoperative events (39% vs 12%, p=0.005); the rate of events was still higher in these patients (32% vs 9%, p=0.013), even when excluding early postoperative AF (ie, within 48 h). Event-free survival was significantly lower in the ExPHT group (all events: 5-year: 60+/-8% vs 88+/-5%, p=0.007, events without early AF: 5-year: 67+/-7% vs 90+/-4%, p=0.02). Using Cox multivariable analysis, ExPHT remained independently associated with higher risk of postoperative events in all models (all p</=0.04). CONCLUSIONS: ExPHT is associated with increased risk of adverse cardiac events following mitral valve surgery in patients with primary MR. [less ▲]

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See detailThe impact of expectations on commitment of newcomers.
Bertrand, Françoise ULg; Tibbax, V.; Hansez, Isabelle ULg

Conference (2009, November 05)

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See detailThe impact of expertise on the capture of sketched intentions: perspectives for remote cooperative design
Sutera, Jennifer; Yang, Maria C.; Elsen, Catherine ULg

in Lecture Notes in Computer Science (2014), 8683

The paper describes the way expertise and field-knowledge can impact the transfer of graphical intentions during architectural cooperative design. The analysis of 28 controlled experiments reveals what ... [more ▼]

The paper describes the way expertise and field-knowledge can impact the transfer of graphical intentions during architectural cooperative design. The analysis of 28 controlled experiments reveals what matters in transmitting architectural intents and more specifically underlines how novices’ intuitive, deductive processes based on previous and embodied experiences interestingly complement experts’ knowledge of the architectural field and its semantics. The results directly inform how we, as researchers, designers and engineers, should take advantage of both novices’ and experts’ strategies to develop tools, methods or interfaces to support next generation cooperative design. [less ▲]

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