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

Poster (2012, February 10)

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 ... [more ▼]

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 respiration soil for 3 years. We will present our first results. [less ▲]

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See detailImpact of cultivation practices on soil respiration
Dufranne, Delphine ULiege; Vancutsem, Françoise ULiege; Bodson, Bernard ULiege 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 Cultural Values on Customer Coping Responses After Service Failure
Van Vaerenbergh, Yves; De Keyser, Arne; Hazee, Simon ULiege

Scientific conference (2015, March)

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

Poster (2009, September 17)

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See detailImpact of cutting frequency on the vigour of Rumex obtusifolius
Stilmant, Didier ULiege; Bodson, Bernard ULiege; 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 ULiege

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 cyclonic and anticyclonic activity on Greenland ice sheet surface mass balance variation during 1980–2013
Chen, L.; Fettweis, Xavier ULiege; Knudsen, E. et al

in International Journal of Climatology (2016)

The Greenland ice sheet (GrIS) has experienced dramatic ice loss during recent decades, but the drivers of the surface mass balance (SMB) variation remain unclear. From a dynamical perspective ... [more ▼]

The Greenland ice sheet (GrIS) has experienced dramatic ice loss during recent decades, but the drivers of the surface mass balance (SMB) variation remain unclear. From a dynamical perspective, extratropical cyclones and anticyclones are the major systems influencing Greenland weather conditions. Seasonal cyclonic and anticyclonic activities have been quantified for the area of 50°–90°N, 80°W–10°E during 1980–2013. Based on a singular value decomposition (SVD) analysis, we investigated the role of synoptic scale cyclonic and anticyclonic activities in determining snow accumulation (SA) and surface air temperature (SAT). Thus, the SA-driven and melt-driven SMB variability has been determined. SA-related synoptic patterns identified from the leading and the second SVD modes explain up to 80% of the inter-annual SMB variance, especially in southern and northwestern Greenland, where we found the largest and second largest amount of annual SA. SAT-related patterns account for up to 80% of the inter-annual SMB variation along the west and northwest coast of Greenland, where significant surface mass loss has been observed over the last decades. It should be noted that the negative phase of the SA-related pattern derived from the first SVD mode in June-July-August and the positive phase of the SAT-related (anti)cyclonic patterns have occurred more frequently since 2005, meaning that the phase change of these patterns has made a major contribution to the accelerated GrIS surface ice loss during recent years. [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 ULiege

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 ULiege 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 dependency on the distribution of p-value
Ernst, Marie ULiege; Swan, Yvik ULiege

Conference (2017, August 01)

We study the impact of dependence assumptions on the distribution of p-values and quantiles for repeated testing on dependent data. This leads us to considering the general problem of the quality of a ... [more ▼]

We study the impact of dependence assumptions on the distribution of p-values and quantiles for repeated testing on dependent data. This leads us to considering the general problem of the quality of a binomial approximation to the distribution of a sum of dependent indicator variables. Whenever possible we use classical and adhoc versions of Stein’s method to provide tight bounds on classical probability distances. In many cases, however, the relevant expressions are intractable and we resort to empirical analysis by extensive simulations. We apply our findings to a realistic real-life scenario. [less ▲]

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See detailIMPACT OF DEPTH AND SOIL COMPACTION ON BACTERIAL DIVERSITY IN SOIL
Stroobants, Aurore ULiege; 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 ULiege; Nyssen, Anne-Sophie ULiege

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 ULiege; Vandeweerd, Jean-Michel ULiege; 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 Diesel generator limitations in the robust sizing of isolated hybrid Microgrids including PV and batteries
Balderrama Subieta, Sergio Luis ULiege; Canedo, Walter; Lemort, Vincent ULiege et al

in Proceedings of ECOS 2016 - the 30th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems (2017, July)

The recent developments in PV and Lion-ion batteries along with the maturity of gensets technology to provide energy to isolated systems has fostered the use of hybrid micro-grids for rural ... [more ▼]

The recent developments in PV and Lion-ion batteries along with the maturity of gensets technology to provide energy to isolated systems has fostered the use of hybrid micro-grids for rural electrification. In this context, the optimal coupling of different technologies and the minimization of the cost to the final consumer are the objects of a number of previous researches. However, the approach usually relies on deterministic linear programming optimizations (LP), which do not allow to model certain non-linearities and limitations of the components. This paper aims at filling this gap by proposing an optimization of such system, with a detailed representation of each component. The case study of an isolated village (Las Misiones, Bolivia) with a peak electricity consumption of 9.2 MW is analyzed. The considered system comprises a diesel generator; a PV array and Li-Ion batteries whose nominal capacities should be optimized. A robust optimization tool is first proposed with an LP formulation and the net present cost as objective function. The basic model is then modified to take into account more complex operating characteristics of a gen-set operating in part-load. To that aim, the LP problem is changed into a mixed integer linear programing formulation. Results indicate that the more detailed constraints influence the final design of the system and negatively impact the total cost. [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

Detailed reference viewed: 169 (1 ULiège)
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)

Detailed reference viewed: 17 (1 ULiège)
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 ULiege; 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 ULiege; MELON, Pierre ULiege; 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 ULiege; Rollin, Frédéric ULiege; Votion, Dominique ULiege et al

in Plügers Archives European Journal of Physiology (1998)

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See detailImpact of different plant secondary metabolites addition: saponin, tannic acid, salicin and aloin on glucose anaerobic co-digestion
Mambanzulua Ngoma, Philippe; Hiligsmann, Serge ULiege; Sumbu Zola, Eric et al

in Fermentation Technology (2015), 4(1), 1-11

Vegetal waste and some wastewater of agro-food industries contain plant secondary metabolites (PSMs). It was showed in nutritional researches that these substances such as saponins and tannins reduced the ... [more ▼]

Vegetal waste and some wastewater of agro-food industries contain plant secondary metabolites (PSMs). It was showed in nutritional researches that these substances such as saponins and tannins reduced the methane production in the rumen. To our knowledge no study was done in the waste treatment domain to evaluate the inhibitory effect of the principal glycosidic metabolites from the wastewater or vegetal waste on their own methane-producing anaerobic digestion. Therefore in this paper BMP tests were carried out at 30°C with four commercial PSMs (CPSMs) in mixture with glucose monohydrate (Gl) used as control sample. These CPSMs were saponin from Quilaja Saponaria Molina Pract (Sap), tannic acid (Tan), salicin (Sal) and aloin from Curacao Aloe (Alo) representing respectively saponins, tannins, alcoholic glycosides and anthraquinones sources. Acidogenesis and acetogenesis were recorded for all the mixtures of Gl and CPSMs; however their conversion rates decreased with the increase of the concentrations of CPSMs. By contrast, the methanogenesis was inhibited at concentrations of CPSMs above 0.3 g/l. The inhibition degree for aromatic compounds on the anaerobic biodegradation of Gl seemed directly to depend on the numbers of benzene rings in the medium and the synergism. Thus, the highest inhibition of the biogas production from Gl was recorded for Alo, followed by Sap, Tan and Sal. However, the highest inhibition of the methane production from Gl was recorded with Sap, Alo, Tan and Sal. It was supposed that the toxicity potentials of these PSMs on the own biomethanization would be in following decreasing order: Sap or Alo, Tan and Sal. Therefore, the concentration of PSMs alone or in mixture in a digester should be bellow 0.3 g/l. for a better methanization . [less ▲]

Detailed reference viewed: 132 (9 ULiège)