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See detailDynamics of dissolved inorganic carbon and aquatic metabolism in the Tana River basin, Kenya
Tamooh, F.; Borges, Alberto ULg; Meysman, F. J. R. et al

in Biogeosciences (2013), 10(11), 6911-6928

A basin-wide study was conducted in the Tana River basin (Kenya) in February 2008 (dry season), September–November 2009 (wet season) and June– July 2010 (end of the wet season) to assess the dynamics and ... [more ▼]

A basin-wide study was conducted in the Tana River basin (Kenya) in February 2008 (dry season), September–November 2009 (wet season) and June– July 2010 (end of the wet season) to assess the dynamics and sources of dissolved inorganic carbon (DIC) as well as to quantify CO2 fluxes, community respiration (R), and primary production (P). Samples were collected along the altitudinal gradient (from 3600 to 8 m) in several headwater streams, reservoirs (Kamburu and Masinga), and the Tana River mainstream. DIC concentrations ranged from 0.2 to 4.8 mmol L−1, with exceptionally high values (3.5±1.6 mmol L−1) in Nyambene Hills tributaries. The wide range of 13CDIC values (−15.0 to −2.4 ‰) indicate variable sources of DIC, with headwater streams recording more positive signatures compared to the Tana River mainstream. With with only a few exceptions, the entire riverine network was supersaturated in CO2, implying the system is a net source of CO2 to the atmosphere. pCO2 values were generally higher in the lower Tana River mainstream compared to headwater tributaries, opposite to the pattern typically observed in other river networks. This was attributed to high suspended sediment in the Tana River mainstream fuelling in-stream community respiration and net heterotrophy. This was particularly evident during the 2009 wet season campaign (median pCO2 of 1432 ppm) compared to the 2010 end of the wet season (1002 ppm) and 2008 dry season(579 ppm). First-order estimates show that in-stream community respiration was responsible for the bulk of total CO2 evasion (77 to 114 %) in the Tana River mainstream, while in the tributaries, this could only account for 5 to 68% of total CO2 evasion. This suggests that CO2 evasion in the tributaries was to a substantial degree sustained by benthic mineralisation and/or lateral inputs of CO2-oversaturated groundwater. While sediment loads increased downstream and thus light availability decreased in the water column, both chlorophyll a (0.2 to 9.6 μg L−1) and primary production (0.004 to 7.38 μmol CL−1 h−1) increased consistently downstream. Diurnal fluctuations of biogeochemical processes were examined at three different sites along the river continuum (headwater, reservoir and mainstream), and were found to be substantial only in the headwater stream, moderate in the reservoir and not detectable in the Tana River mainstream. The pronounced diurnal fluctuations observed in the headwater stream were largely regulated by periphyton as deduced from the low chlorophyll a in the water column. [less ▲]

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See detailDynamics of dissolved inorganic carbon in the Tana River Basin, Kenya
Tamooh; Meysman, F; Van den Meersche, K et al

Conference (2012, July 08)

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See detailDynamics of Dowstream Entry in Postal Markets
Gautier, Axel ULg

in Crew, Michael; Kleindorfer, Paul (Eds.) Liberalization of the Postal and Delivery Sector (2006)

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See detailDynamics of Elasto-Inertial Turbulence in Flows with Polymer Additives
Terrapon, Vincent ULg; Dubief, Yves; Soria, Julio

Scientific conference (2012, December 07)

Elasto-inertial turbulence is a new state of turbulence that may occur in certain viscoelastic flows, in particular flows with polymer additives. The dynamics of elasto-inertial turbulence is here ... [more ▼]

Elasto-inertial turbulence is a new state of turbulence that may occur in certain viscoelastic flows, in particular flows with polymer additives. The dynamics of elasto-inertial turbulence is here investigated numerically from the perspective of the coupling between polymer dynamics and flow structures. The resulting mechanism helps resolve a long standing controversy in the understanding of polymer drag reduction and explains the phenomenon of early turbulence, or onset of turbulence at lower Reynolds numbers than for Newtonian flows, previously observed in polymeric flows. In particular, we show that the introduction of small perturbations into the polymeric flow excites the unstable nature of the nonlinear advection term, resulting in the formation of sheets or cliffs of polymer stretch. These sheets of high polymer stretch, hosting a significant increase in extensional viscosity, create a strong local anisotropy, with a formation of local low-speed jet-like flow. The response of the flow is through pressure, whose role is to redistribute energy across components of momentum, resulting in the formation of waves, or trains of alternating rotational and straining motions. The mechanism shares some similarity with the Kelvin-Helmholtz instability, except that the thickness of these sheets is too close to the Kolmogorov scale for vortices to be created. Once triggered, EIT is self-sustained since the elastic instability creates the very velocity fluctuations it feeds upon. [less ▲]

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See detailDynamics of Elasto-Inertial Turbulence in Flows with Polymer Additives
Terrapon, Vincent ULg; Dubief, Yves; Soria, Julio

in Proceedings of the 8th International Symposium on Turbulence and Shear Flow Phenomena (TSFP-8) (2013, August 30)

The dynamics of elasto-inertial turbulence is investigated numerically from the perspective of the coupling between polymer dynamics and flow structures. In particular, direct numerical simulations of ... [more ▼]

The dynamics of elasto-inertial turbulence is investigated numerically from the perspective of the coupling between polymer dynamics and flow structures. In particular, direct numerical simulations of channel flow with Reynolds numbers ranging from 1000 to 6000 are used to study the formation and dynamics of elastic instabilities and their effects on the flow. Based on the splitting of the pressure into inertial and polymeric contributions, it is shown that the trains of cylindrical structures around sheets of high polymer extension that are characteristics to elasto-inertial turbulence are mostly driven by polymeric contributions. [less ▲]

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See detailDynamics of erythropoietic recovery following bone marrow transplantation: role of marrow proliferative capacity and erythropoietin production in autologous versus allogeneic transplants.
Beguin, Yves ULg; Oris, Renée ULg; Fillet, Georges ULg

in Bone Marrow Transplantation (1993), 11(4), 285-92

The mechanisms of erythrocyte recovery after BMT are not known. We investigated the respective role of marrow function and erythropoietin production in 31 ABMT and 47 allogeneic BMT by analysing ... [more ▼]

The mechanisms of erythrocyte recovery after BMT are not known. We investigated the respective role of marrow function and erythropoietin production in 31 ABMT and 47 allogeneic BMT by analysing peripheral counts, serum erythropoietin levels, and serum transferrin receptor (TfR) levels which have been shown to be a quantitative measurement of erythropoiesis. Median times to complete neutrophil (25 vs 48 days, p < 0.0001) and platelet (45 vs 263 days, p < 0.001) recovery were faster after allogeneic BMT than ABMT, but complete erythrocyte recovery was slower (218 vs 101 days, p < 0.001). After ABMT, erythrocyte recovery paralleled that of neutrophils and platelets, and erythropoietin levels remained appropriate for the degree of anemia. After allogeneic BMT, erythrocytes developed independently of the other cell lines and defective erythropoietin production delayed recovery of adequate erythropoietic activity. This correlated with an alteration of renal function only in those patients remaining erythropoietin deficient beyond day 180. However, supranormal erythropoietin levels in interstitial pneumonia suggests that erythropoietin response to hypoxia is not abrogated. CMV infection could also affect erythropoiesis through erythropoietin production after ABMT as well as allogeneic BMT. It is concluded that after ABMT the development of erythropoiesis is determined by the overall marrow proliferative activity and erythropoietin plays only a facilitating role. After allogeneic BMT, erythropoiesis depends on erythropoietin levels which remain inadequate for prolonged periods of time. The results suggest that the administration of recombinant human erythropoietin could reduce transfusion requirements after BMT. [less ▲]

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See detailThe Dynamics of Fair Trade as a Mixed-form Market
Becchetti, Leonardo; Huybrechts, Benjamin ULg

in Journal of Business Ethics (2008), 81(4), 733-750

This article analyses the Fair Trade sector as a “mixed-form market,” i.e., a market in which different types of players (in this case, nonprofit, co-operative and for-profit organizations) coexist and ... [more ▼]

This article analyses the Fair Trade sector as a “mixed-form market,” i.e., a market in which different types of players (in this case, nonprofit, co-operative and for-profit organizations) coexist and compete. The purposes of this article are (1) to understand the factors that have led Fair Trade to become a mixed-form market and (2) to propose some trails to understand the market dynamics that result from the interactions between the different types of players. We start by defining briefly Fair Trade, its different dimensions (including the “fair” quality of the products) and its organizational landscape, focusing on the distinction between the pioneer “Alternative Trading Organizations” and the second-mover companies. Then, we recall the theoretical emergence factors for each type of organization (nonprofit, co-operative and for-profit) and apply these emergence factors to the context of Fair Trade. This analysis allows us to capture the specificities of each type of operator with regard to Fair Trade and, thus, to have a better understanding of the dynamics in the sector. Such dynamics includes competition, but also conflict and partnership. Our analysis includes elements on ethical imitation, consumers’ behaviors, effects on welfare and the role of the government. [less ▲]

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See detailDynamics of flood-freeze cycles during the SIMBA experiment (Brussels and Liège Stations - Bellingshaussen Sea, Antarctica)
Tison, Jean Louis; Brabant, Frederic; Geilfus, Nicolas-Xavier ULg et al

Poster (2009, March)

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See detailDynamics of global scale electron and proton precipitation induced by a solar wind pressure pulse
Meurant, M.; Gérard, Jean-Claude ULg; Hubert, Benoît ULg et al

in Geophysical Research Letters (2003), 30(20),

[1] On April 28 2001, simultaneous global images of electron and proton aurora were obtained by IMAGE- FUV following a sudden increase of solar wind dynamic pressure. The local time and intensity ... [more ▼]

[1] On April 28 2001, simultaneous global images of electron and proton aurora were obtained by IMAGE- FUV following a sudden increase of solar wind dynamic pressure. The local time and intensity distribution of both types of precipitation are examined and compared. It is found that the electron and the proton precipitation both start in the post noon sector and expand concurrently, but the expansion into the nightside starts sooner for the protons than for the electrons. The characteristic rise time in the onset sector is on the order of 6 minutes. A distinct dynamics and morphology of electron and proton precipitation is observed in the nightside sector. DMSP electron measurements in the afternoon sector indicate that the shock has a significant effect on the electron spectral characteristics. It is suggested that the various Alfven frequencies generated by the shock account for the two different speeds of propagation of the disturbance. [less ▲]

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See detailDynamics of greenhouse gases (CO2, CH4, N2O) along the Zambezi River and major tributaries, and their importance in the riverine carbon budget
Teodoru, C. R.; Nyoni, F. C.; Borges, Alberto ULg et al

in Biogeosciences (2015), 12(8), 2431-2453

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See detailDynamics of H+ fluxes in mitochondrial membrane.
Sluse, Francis ULg; Jarmuszkiewicz, W.

in Rengel, Z. (Ed.) Handbook of plan growth : pH as the master variable (2001)

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See detailDynamics of hybrid switching diffusions SIRS model
Settati, Adel; Lahrouz, Aadil; El Jarroudi, Mustapha et al

in Journal of Applied Mathematics and Computing (2015)

The main aim of this paper is to study the effect of the environmental noises in the asymptotic properties of a stochastic version of the classical SIRS epidemic model. The model studied here include ... [more ▼]

The main aim of this paper is to study the effect of the environmental noises in the asymptotic properties of a stochastic version of the classical SIRS epidemic model. The model studied here include white noise and telegraph noise modeled by Markovian switching. We obtained conditions for extinction both in probability one and in pth moment. We also established the persistence of disease under different conditions on the intensities of noises, the parameters of the model and the stationary distribution of the Markov chain. The highlight point of our work is that our conditions are sufficient and almost necessary for extinction and persistence of the epidemic. The presented results are demonstrated by numerical simulations. [less ▲]

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See detailThe dynamics of inequality in Katanga, D.R.Congo. A conversation with Bourdieu
Rubbers, Benjamin ULg

Conference (2016, February 10)

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See detailDynamics of inorganic carbon in surface waters off the Galician coast
Borges, Alberto ULg; Keir, R.; Larsen, S. E. et al

Conference (2000)

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See detailDynamics of Internalization and Recycling of the pro-Metastatic Membrane Type 4-Matrix Metalloproteinase (MT4-MMP) in Breast Cancer cells
Truong, Alice ULg; Yip, Cassandre ULg; PAYE, Alexandra ULg et al

Poster (2015, October 26)

MT4-MMP (MMP17) is a glycosyl-phosphatidyl inositol-anchored membrane-type matrix metalloproteinase expressed at the cell surface of human breast cancer cells. In triple negative breast cancer, MT4-MMP ... [more ▼]

MT4-MMP (MMP17) is a glycosyl-phosphatidyl inositol-anchored membrane-type matrix metalloproteinase expressed at the cell surface of human breast cancer cells. In triple negative breast cancer, MT4-MMP promotes primary tumor growth and lung metastases. Recently, we demonstrated that EGFR activation and signaling are enhanced by MT4-MMP in a non-proteolytic dependent manner. While trafficking and internalization of EGFR was extensively investigated, little is known about MT4-MMP. Here, we investigated the dimerization, internalization and recycling dynamics of MT4-MMP and its mutated inactive form MT4-MMP-E249A. We demonstrate that MT4-MMP forms dimers and oligomers at the cell surface, a process that was not inhibited neither by broad-spectrum MMP inhibitors (GM6001 and BB94) nor TIMP-2. MT4-MMP is internalized in early endosomes from 10 minutes to 60 minutes. Once internalized, some amount of MT4-MMP is auto-degraded, whereas its inert form E249A was found intact. Large part of the internalized enzyme was recycled intact at the cell surface. By exploring its endocytosis, we found that MT4-MMP is internalized by the CLIC/GEEC pathway, a mechanism that differs from other MT-MMP members. Overall, we provided a new mechanistic insight on the regulatory mechanisms of MT4-MMP in human breast cancer cells. We also, highlighted unique features of MT4-MMP among membrane-associated MMPs, which may be useful for the design of novel therapeutic strategies for metastatic breast cancer. [less ▲]

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See detailDynamics of Internalization and Recycling of the Pro-Metastatic Membrane Type 4-Matrix Metalloproteinase (MT4-MMP) in Breast Cancer Cells
Truong, Alice ULg; Yip, Cassandre ULg; PAYE, Alexandra ULg et al

in FEBS Journal (2016), 283(4), 704-22

MT4-MMP (MMP17) is a glycosylphosphatidyl inositol (GPI)-anchored membrane-type MMP expressed on the cell surface of human breast cancer cells. In triple negative breast cancer cells, MT4-MMP promotes ... [more ▼]

MT4-MMP (MMP17) is a glycosylphosphatidyl inositol (GPI)-anchored membrane-type MMP expressed on the cell surface of human breast cancer cells. In triple negative breast cancer cells, MT4-MMP promotes primary tumor growth and lung metastases. Although trafficking and internalization of the transmembrane MT1-MMP have been extensively investigated, little is known about the regulatory mechanisms of the GPI-anchored MT4-MMP. Here, we investigated the fate and cellular trafficking of MT4-MMP by analyzing its homophilic complex interactions, internalization and recycling dynamics compared to an inert form, MT4-MMP-E249A. Oligomeric and dimeric complexes were analyzed by co-transfection of cells with FLAG- or Myc-tagged MT4-MMP by reducing and non-reducing immunoblots and co-immunoprecipitation experiments. The trafficking of MT4-MMP was studied using an antibody feeding assay and confocal microscopy analysis or cell surface protein biotinylation and Western blot analysis. We demonstrate that MT4-MMP forms homophilic complexes at the cell surface, internalizes in early endosomes, and some of the enzyme is either auto-degraded or recycled to the cell surface. Our data indicate that MT4-MMP is internalized by the CLIC/GEEC pathway, a mechanism that differs from other MT-MMP members. Although MT4-MMP localizes with caveolin-1, MT4-MMP internalization was not affected by inhibitors of caveolin-1 or clathrin endocytosis pathways but was reduced by cdc42 or RhoA silencing with siRNA. We provide a new mechanistic insight into the regulatory mechanisms of MT4-MMP, which may have implications in the design of novel therapeutic strategies for metastatic breast cancer. This article is protected by copyright. All rights reserved. [less ▲]

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See detailDynamics of ligands on gold surface to obtain Janus nanoclusters: A theoretical and experimental investigation
Lugo Preciado, Jesús Gustavo ULg

Doctoral thesis (2016)

We performed a joint computational – experimental investigation of the dynamics of ligand exchange on gold nanoclusters (GNC) surface with the aim to understand how to control the structural and optical ... [more ▼]

We performed a joint computational – experimental investigation of the dynamics of ligand exchange on gold nanoclusters (GNC) surface with the aim to understand how to control the structural and optical properties of GNC through the design of their ligand shell. Our computational studies were carried out in the framework of the Kohn – Sham implementation of density functional theory in quantum chemistry. We analyzed the main features of UV – Vis spectra computed at the TD – DFT / CAM – B3LYP level for the Au13, Au25, and Au28 metallic cores protected by thiolate, chloride, and phosphine ligands. Our results show that it is possible to tune the energy of the lowest absorption band of gold clusters by ligand shell engineering in order to control the charge redistribution between ligand shell and metallic core. In parallel we synthesized a set of Au25(ATP)x(TP)18 – x clusters with different ATP/TP ratios using an adapted Demessence protocol by combining 4ATP (4 – aminothiophenol) and TP (thiophenol) ligands. ESI – MS measurements evidence that for these mixed ligand shells the Au25 nuclearity is preserved. However, the addition of the DDT (1 – dodecanethiol) ligand in the mixture leads to nanoparticle formation. FT – IR spectroscopy confirms the absorption of two different ligands on the gold surface and SAXS shows that we have a good correlation between the distance between two clusters and the length of the ligand protecting them. Furthermore, we collaborated with the Institut Charles Gerhardt in the Université de Montpellier, France whose experimental results show that several n – heterocyclic carbenes (NHC) bearing different groups on the N atoms exhibit similar reactivity when protecting a gold nanosurface. The formation of the bis(NHC) AuI gold complexes is evidenced by 13C NMR. In order to complement and interpret the experimental results, we carried out a computational study of the adsorption of a single NHC on Au38 which acts as a model for the gold surface, as well as of the fully NHC ligated Au38 cluster. The joint experimental – theoretical study, in particular the comparison between computed and 13C NMR spectra allows proposing a possible mechanism explaining the formation of [NHC – Au – NHC]+ complexes and the erosion experienced by the nanoparticle. Finally, we carried out a comparison of the mode of binding and the structural and optical properties of the fully ligated PH3 and NHC GNC with metallic cores of different nuclearities. Our computations show that the Au – P bond is weaker than the Au – NHC one. Additionally, our study confirms that the ligand – to – metal charge transfer is an important parameter for understanding the electronic transitions and the UV – Vis spectra in these clusters. Our computations on the PH3 – Au38 set of complexes show that there is a site selectivity for the reactivity for the PH3 interacting on the Au38 surface which allows predicting where the PH3 is likely to be adsorbed. This selectivity is not observed in the case of the binding of a single NHC ligand on the surface of the Au38 cluster. [less ▲]

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