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See detailImpact of cultivation practices on soil respiration
Dufranne, Delphine ULg; Vancutsem, Françoise ULg; Bodson, Bernard ULg et al

Poster (2012, February 08)

In addition to its, evident, food supply function, agriculture is subjected to various pressures and has to respond to many challenges like reducing its CO2 emissions, maintaining or improving the soil ... [more ▼]

In addition to its, evident, food supply function, agriculture is subjected to various pressures and has to respond to many challenges like reducing its CO2 emissions, maintaining or improving the soil quality, maintaining productivity, sequestrating of the carbon stock in soil... Cultivation practices are known to induce a modification of soil organic matter quantity, quality and spatial distribution, which may impact dry matter decomposition kinetics. In order to bring answers to these questions, a multidisciplinary project (SOLRESIDUS) was set up by the University of Liege, Gembloux Agro-Bio Tech in collaboration with Walloon Agricultural Research Centre (CRA-W). The aim was to investigate the impact of cultivation practices (tillage and residue restitution) on crop growth, yield and environment, as well as on soil properties and on activities. In the present study, we focused on the impacts on soil CO2 fluxes. The experimental site is situated in Gembloux, in the Belgian loamy region. The plot is divided into 4 latin squares where two tillage modalities (plough after 2 stubble breaking vs only 2 stubble breaking) and two straw management practices (restitution vs. exportation) were compared. For 3 years, soil respiration was measured with automatic and manual dynamic soil chambers. Moreover, soil respiration was measured as well in cropping zone (total respiration) as in root exclusion zones created with root exclusion cylinders (heterotrophic respiration). As first results, we observed: -a significantly higher flux in plots with residue restitution, which is clearly explained by the larger amount of organic carbon prone to decomposition; -a decrease of standardized heterotrophic respiration (linked with residue decomposition) during growing seasons; -no significant differences in soil respiration between tillage modalities after 3 growing seasons. The experiment is still in progress, more years being necessary in order to evaluate the long-term impacts of cultivation practices on soil respiration. [less ▲]

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See detailThe impact of culture on cognitive performance in neuropsychological tests.
Schmitz, Xavier ULg; Mardaga, Julie; Meulemans, Thierry ULg

Poster (2009, September 17)

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See detailImpact of cutting frequency on the vigour of Rumex obtusifolius
Stilmant, Didier ULg; Bodson, Bernard ULg; Vrancken, C. et al

in Grass & Forage Science (2010), 65(2), 147-153

The control of Rumex obtusifolius, even with the use of herbicides, is difficult in permanent grasslands where R. obtusifolius reduces both productivity and nutritive value of herbage. It is important to ... [more ▼]

The control of Rumex obtusifolius, even with the use of herbicides, is difficult in permanent grasslands where R. obtusifolius reduces both productivity and nutritive value of herbage. It is important to find alternative approaches to managing R. obtusifolius. Two greenhouse experiments were conducted to compare the impact of different cutting frequencies, which simulated grazing (three cuts), silage making (two cuts) and hay making (one cut) on shoot and root measurements of the vigour of R. obtusifolius. In both experiments the same cutting frequencies were imposed but in Experiment 1 the treatments were imposed for 2 years and in Experiment 2 for 1 year. Compared to the silage-making and hay-making treatments, there was a reduction in the vigour of the aerial parts of R. obtusifolius on the grazing treatment, associated with a reduction in the number of leaves (Experiment 1), in the size of the largest leaf (Experiment 1) and in the herbage mass of dry matter (Experiments 1 and 2). Roots had higher concentrations of total soluble sugar and lower concentrations of starch in the grazing treatment than in the other treatments. These results showed that a reduction in the vigour of R. obtusifolius in permanent grasslands is possible only if the plants are submitted to a high frequency of defoliation under cutting or grazing. [less ▲]

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See detailImpact of cyclic hypoxia on HIF-1a regulation in endothelial cells: new insights for anti-tumor treatments
Martinive, Philippe ULg

in FEBS Journal (2008)

Impact of cyclic hypoxia on HIF-1alpha regulation in endothelial cells - new insights for anti-tumor treatments.Martinive P, Defresne F, Quaghebeur E, Daneau G, Crokart N, Grégoire V, Gallez B, Dessy C ... [more ▼]

Impact of cyclic hypoxia on HIF-1alpha regulation in endothelial cells - new insights for anti-tumor treatments.Martinive P, Defresne F, Quaghebeur E, Daneau G, Crokart N, Grégoire V, Gallez B, Dessy C, Feron O. Unit of Pharmacology and Therapeutics, Université catholique de Louvain, Brussels, Belgium. Heterogeneities in tumor blood flow are associated with cyclic changes in pO(2) or cyclic hypoxia. A major difference from O(2) diffusion-limited or chronic hypoxia is that the tumor vasculature itself may be directly influenced by the fluctuating hypoxic environment, and the reoxygenation phases complicate the usual hypoxia-induced phenotypic pattern. Here, we determined the cyclic hypoxia-driven pathways that modulate hypoxia inducible factor (HIF)-1alpha abundance in endothelial cells to identify possible therapeutic targets. We found that exposure of endothelial cells to cycles of hypoxia/reoxygenation led to accumulation of HIF-1alpha during the hypoxic periods and the phosphorylation of protein kinase B (Akt), extracellular regulated kinase (ERK) and endothelial nitric oxide synthase (eNOS) during the reoxygenation phases. We identified stimulation of mitochondrial respiration and activation of the phosphoinositide-3 kinase (PI3K)/Akt pathway during intervening reoxygenation periods as major triggers of the stabilization of HIF-1alpha. We also found that the NOS inhibitor nitro-l-arginine methyl ester further stimulated the cyclic hypoxia-driven HIF-1alpha accumulation and the associated gain in endothelial cell survival, thereby mirroring the effects of a PI3K/Akt inhibitor. However, combination of both drugs resulted in a net reduction in HIF-1alpha and a dramatic in decrease in endothelial cell survival. In conclusion, this study identified cyclic hypoxia, as reported in many tumor types, as a unique biological challenge for endothelial cells that promotes their survival in a HIF-1alpha-dependent manner through phenotypic alterations occurring during the reoxygenation periods. These observations also indicate the potential of combining Akt-targeting drugs with anti-angiogenic drugs, in particular those interfering with the NO pathway. PMID: 19077164 [PubMed - as supplied by publisher [less ▲]

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See detailImpact of Data Structure on the Estimators R-Square and adjusted R-Square in Linear Regression
Akossou, A. Y. J.; Palm, Rodolphe ULg

in International Journal of Mathematics and Computation (2013), 20(3), 84-93

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See detailImpact of delays on a consensus-based primary frequency control scheme for AC systems connected by a multi-terminal HVDC grid
Dai, Jing; Phulpin, Yannick; Sarlette, Alain ULg et al

in Proceedings of the 2010 IREP Symposium - Bulk Power Systems Dynamics and Control - VIII (2010, August)

This paper addresses the problem of sharing primary frequency control reserves among nonsynchronous AC systems connected by a multi-terminal HVDC grid. We focus on a control scheme that modifies the power ... [more ▼]

This paper addresses the problem of sharing primary frequency control reserves among nonsynchronous AC systems connected by a multi-terminal HVDC grid. We focus on a control scheme that modifies the power injections from the different areas into the DC grid based on remote measurements of the other areas’ frequencies. This scheme is proposed and applied to a simplified system in a previous work by the authors. The current paper investigates the effects of delays on the control scheme’s effectiveness. The study shows that there generally exists a maximum acceptable delay, beyond which the areas’ frequency deviations fail to converge to an equilibrium point. This constraint should be taken into account when commissioning such a control scheme. [less ▲]

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See detailIMPACT OF DEPTH AND SOIL COMPACTION ON BACTERIAL DIVERSITY IN SOIL
Stroobants, Aurore ULg; Degrune, Florine; Olivier, Claire et al

Poster (2012, August 19)

Bacteria are the most abundant and diverse microorganisms in soils. The amount of bacteria in soils can reach 10^10 cells per gram of soil. These organisms are involved in various processes in ... [more ▼]

Bacteria are the most abundant and diverse microorganisms in soils. The amount of bacteria in soils can reach 10^10 cells per gram of soil. These organisms are involved in various processes in agroecosystems such as nutrient cycling, contributing to plant nutrition, plant health and soil structure. The knowledge about this diversity is limited because only one percent of these organisms can be cultured by laboratory methods. During the last decades, many molecular-based techniques have been developed to assess the diversity of bacterial communities. The aim of this study was to determine the quantity and diversity of bacteria in two agricultural soils with differents soil management practices (tillage and no tillage) at different depths (10, 30 and 45 centimeters) and different compaction levels (high and low). Quantity was evaluated by real time PCR and diversity was analysed by the DGGE (Denaturing Gradient Gel Electrophoresis) technique. The results show that soil management has an impact on bacterial quantity at 45 centimeters and quantity is higher in till soil. Compaction level affects the bacterial quantity in till soil, quantity is higher in low compaction. And finally, depth influences the bacterial quantity in till and no till soil. In both soils, quantity decreases with the depth. The results will be presented and discussed on the poster. [less ▲]

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See detailImpact of depth perception and movement freedom on performance in fine surgical tasks
Blavier, Adelaïde ULg; Nyssen, Anne-Sophie ULg

Conference (2005, May 27)

This study aimed to evaluate the impact of new technology and depth perception on surgical tasks performance. Comparing to classical minimal access surgery, new robotic system allows to recover a 3D view ... [more ▼]

This study aimed to evaluate the impact of new technology and depth perception on surgical tasks performance. Comparing to classical minimal access surgery, new robotic system allows to recover a 3D view and all degrees of freedom for instruments movement. To separately evaluate the benefit of robotic technology and the effect of depth perception, 60 medical students without any surgical experience were divided in 3 groups: one using the robotic system in 3D, another using robotic system in 2D, and the third using traditional laparoscopic technique (2D view). After a phase of familiarisation with the technique of their condition, subjects performed four specific fine motor tasks of increasing complexity. We measured the speed, the accuracy and their subjective impressions about their performance (satisfaction, self-confidence and difficulty). Our results show robotic system in 3D allows a better performance than classical laparoscopy in all tasks. More particularly, depth perception significantly improves performance in the easiest tasks (robotic system in 3D > robotic system in 2D and classical laparoscopy), while freedom for instruments movement seems to play a role in the most complex tasks (robotic system (2D or 3D) > classical laparoscopy). The subjective impressions analysis reproduces the differences observed from objective measures. [less ▲]

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See detailThe impact of detailed explanatory leaflets on patient satisfaction with urodynamic consultation: A double-blind randomized controlled trial.
Hougardy, Véronique ULg; Vandeweerd, Jean-Michel ULg; Reda, A. A. et al

in Neurourology and Urodynamics (2009), 28(5), 374-9

Aims To develop and validate a scale that is applicable in Belgium to investigate the aspects of female patients' satisfaction with urodynamic consultation, and to use it to measure the impact of a ... [more ▼]

Aims To develop and validate a scale that is applicable in Belgium to investigate the aspects of female patients' satisfaction with urodynamic consultation, and to use it to measure the impact of a detailed explanatory leaflet on their satisfaction. Materials and Methods Question items were obtained from a group consensus (Delphi process). Each item was scored on a five-point Likert scale. The satisfaction scale was administered to two groups of patients attending the clinics for urodynamics. One hundred twenty-nine patients were included in the study and randomized in two groups. One group (n = 60) received a detailed explanatory leaflet about urodynamic consultation and the other did not (n = 69). Responses were subjected to a reliability and principal component analysis (PCA) to achieve data reduction and analysis, and to assess the reliability of the new scale. Relevant items were retained to compare both interventions using regression analysis. Results A 15-item scale was derived from the Delphi process. Exploratory factor analysis suggested a single factor solution with 11 meaningful items. No significant difference was noted in global scores of satisfaction between the two groups (P = 0.051). Conclusions A short-form patient satisfaction scale with acceptable validity and reliability was developed and used to measure patient satisfaction with urodynamic consultation in this population of Belgian women. This study did not provide support for the effectiveness of explanatory leaflets in improving satisfaction. [less ▲]

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See detailImpact of diet in shaping gut microbiota revealed by a comparative study in children from Europe and Rural Africa
De Filippo, C.; Cavalieri, D.; Di Paola, M. et al

in Proceedings of the National Academy of Sciences of the United States of America (2010), 107(33), 14691-14696

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See detailThe impact of diet in shaping microbiota revealed by a comparative study in children from Europe and Rural Africa
De Filippo, C.; Di paola, M.; Ramazzotti, M. et al

Poster (2010, August)

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See detailThe impact of diet in shaping microbiota revealed by a comparative study in children from Europe and Rural Africa
De Filippo, C.; Massart, Sébastien ULg; Di Paola, M. et al

Poster (2011, March)

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See detailImpact of different endurance races on the heart: the point of view of the biologist
LE GOFF, Caroline ULg; MELON, Pierre ULg; Thébault, Jérémie et al

in Book of abstracts of 18th Annual Congress of the ECSS (2013, June)

Objective The aim of this study was to investigate the impact of intense exercise, represented by different endurance races, in relationship with oxidative stress and cardiac markers. In a second time, we ... [more ▼]

Objective The aim of this study was to investigate the impact of intense exercise, represented by different endurance races, in relationship with oxidative stress and cardiac markers. In a second time, we tried to demonstrate if oxidative stress induced by physical activity is a physiological or pathological process, and to establish some issues to diagnose the risk of sudden death in athletes. Methods Four populations were compared, a control group of 16 participants “sedentary” (37 ± 4,39 years old), a group of 24 semi-marathon runners (41 years ± 8,76 years old), a group of 28 marathon runners (44,1 ± 8,37 years old) and a group of 33 ultra-trail runners (45,8 ± 8,7 years old). Three blood tests were drowned, one just before, one just after, and the last three hours after the end of the race.Different oxidative and stress and cardiac biomarkers were measured. The ultra-trail runners will be subject to an echocardiography and an ECG pre- and post-race. For statistical analysis, STATISTICA 10 software was used. We performed a non-parametric test of Kruskal-Wallis for independent sample and a Friedman ANOVA for paired samples. Results Myeloperoxydase increased during exercise, but the release is less important according to the level of training of the runners. GSH/GSSG ratio seems to remain stable during the race but it could increase during the 24 hours post-race. There is a decrease in lipidic peroxidation during exercise. But, we note an increase of creatine kinase, isoform MB, myoglobin and C-reactive protein during the race. We observe an increase of troponin T and natriuretic peptide but with a different kinetic than the kinetic obtained for a myocardial infarction. Medical imaging in ultra-trail runners present cardiac adaptations to endurance training, as left ventricular hypertrophy (LVH) and incomplete right bundle branch block (IRBBB). A decrease of systolic and diastolic volumes of the left ventricle and a decrease of longitudinal strain were observed by echocardiography at the end of the race. Conclusion Endurance races induce the income of oxidative stress objectified by different biomarkers increase, but a cell necrosis is not specially observed. In fact, the increase of the cardiac markers during endurance races but may be explained by a transient modification of myocyte permeability, with a release of pool cytosolic. These races may induce micro-muscle damages causing the appearance of an inflammatory process explaining our observations of markers of inflammation. For the medical imaging, it was observed a myocardial adaptation to training and a transient impairment of ventricular function due to dehydration. [less ▲]

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See detailImpact of different environmental managements on spatial distribution of ventilation in COPD horses
Vandenput, Sandrina ULg; Rollin, Frédéric ULg; Votion, Dominique ULg et al

in Plügers Archives European Journal of Physiology (1998)

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See detailImpact of different scenarios related to the new Common Agricultural Policy on farm income in Wallonia
Burny, Philippe ULg; Terrones Gavira, François ULg; Habran, Maxime ULg

in Lorencowicz, Edmund; Uziak, Jacek; Huyghebaert, Bruno (Eds.) VI International Scientific Symposium "Farm Machinery and Processes Management in Sustainable Agriculture" : Symposium Proceedings (2013)

The Common Agricultural Policy (CAP) has been reformed several times since the treaty of Rome in 1958. For the period 2014-2020 at the European level, a new CAP had to be agreed upon by the 27 Member ... [more ▼]

The Common Agricultural Policy (CAP) has been reformed several times since the treaty of Rome in 1958. For the period 2014-2020 at the European level, a new CAP had to be agreed upon by the 27 Member States and the EU parliament. Discussions were launched in 2010 and several proposals were made. In Belgium, as agricultural policy is regionalized, the Walloon Minister for Agriculture decided to support academic research in order to assess the possible impact of different scenarios on farm income, and so to help the regional authorities to take decisions when the EU legislation would be adopted, giving a large set of possibilities to the Members States/regions. So, different scenarios were defined with the partners of the administration, including farmers' unions, and their impacts on farm income were calculated. [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

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

Detailed reference viewed: 2 (0 ULg)