Browsing
     by title


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

or enter first few letters:   
OK
See detailA nested-grid model with data assimilation in the Gulf of Lions
Vandenbulcke, Luc ULg; Barth, Alexander ULg; Alvera Azcarate, Aïda ULg et al

Conference (2004, April)

When a model combines the use of nested grids and data assimilation, a preliminary, simple, 1D test case showed the interest of combining the different state vectors coming from the different grids, into ... [more ▼]

When a model combines the use of nested grids and data assimilation, a preliminary, simple, 1D test case showed the interest of combining the different state vectors coming from the different grids, into one single vector, and using global error matrices covering all the grids at once. In this case, the assimilation procedure provides errorspace feedback from the fine grid to the coarser grid, which proves to be even more important than the statevector feedback. For data located in the fine grid, assimilation of the same data in the coarse grids is not necessary anymore, as both model and errorspace feedback is performed during assimilation. Large data transfers from local to basin-scale models can be avoided. The GHER hydrodynamic model (for a full description, see e.g. [1]) is applied to a three times nested model covering (a) the Mediterrannean Sea at 1/4 degree, (b) the Liguro-Provencal Bassin at 1/20 degree, and (c) the Gulf of Lions at 1/100 degree. The simulation starts on Januari 1st, 1998, using ECMWF atmospheric forcings and MODB4/MEDAR climatic data. As the model allows mode splitting, the simulation uses 2D timesteps of 3 seconds, and 3D timesteps of 3 minutes, on each grid. A twin experiment is performed. The perturbed initial condition is a delayed model state of the reference run. An initial reduced-rank model errorspace is constructed from 20 EOFs, themselves built from the reference run, over all three grids at the same time. Surface temperature and salinity from the reference run are assimilated in the model every 24 hours, using reduced-rank optimal interpolation (see [2]). Different simulations are implemented, using different ways to combine grid nesting and data assimilation: with or without state vector feedback, with data assimilation only in the local grid, or in the coarser grids, or both, and with or without errorspace feedback (i.e. with 3 separated statevectors or with one global statevector). The comparison of those experiments comfirms that using one global statevector reduces the error in the coarser grids much faster. The effect of data assimilation, and the performances of the different methods, can be examined by calculating RMS errors between the perturbed runs and the reference run. They can also be observed by following the model state trajectory in the EOFspace (for example, using the first three EOFs). In the context of the twin experiment described above, the first assimilation cycle clearly brings the model back in time. This is consistent with the choice of the perturbed initial conditions, being a delayed state of the reference run. The following assimilation cycles have little effect, as the trajectory is already almost brought back on the reference trajectory. If other parameters are modified too (e.g. the atmospheric fluxes), each assimilation cycle has an important effect on the modelstate trajectory. A new experiment performs assimilation in the Gulf of Lions in the spring of 1998 using real observations. Different variables can be assimilated, using data collected during the FETCH campaign: NOAA/AVHRR SST, temperature and salinity from Atalante CTDs, or altimetric data from the ERS2 or TOPEX satellites. [less ▲]

Detailed reference viewed: 40 (0 ULg)
Full Text
See detailNestin expression in cultivated mesenchymal stem cells: Regulation and potential role in their neural differentiation
Wislet-Gendebien, Sabine ULg; Leprince, Pierre ULg; Moonen, Gustave ULg et al

in Glia (2002, May), (Suppl. 1), 87

Bone marrow stromal cells can differentiate into many types of mesenchymal cells, i.e. osteocyte, chondrocyte, fibroblast and adipocyte, but can also differentiate into non-mesenchymal cell, i.e. neural ... [more ▼]

Bone marrow stromal cells can differentiate into many types of mesenchymal cells, i.e. osteocyte, chondrocyte, fibroblast and adipocyte, but can also differentiate into non-mesenchymal cell, i.e. neural cells in appropriate in vivo experimental conditions (Kopen and al.,PNAS,96, 10711,1999, Brazelton and al, Science, 290,1175, 2000, Mezey and al, Science, 290,1179, 2000). In neurological disorders, such as Alzheimer's and Parkinson's diseases, auto-transplantation of neural cell types derived from mesenchymal stem cells offers the potential of replacing lost cells and recovering lost functions. Nestin is an intermediate filament protein predominantly expressed by neural stem cells and is used to identify neural progenitor. In this study, we demonstrate that cultured rat mesenchymal stem cells (rMSC) can express nestin in appropriate conditions. Two factors contribute to the regulation of nestin expression by rMSC : 1) the presence of serum-derived components in the culture medium which repress nestin expression and 2) the cell’s number of passages. LPA and thrombin mimic this serum effect. Furthermore, when nestin- positive cells are trypsinized and resuspended into culture conditions used for neural stem cells (NSC), sphere formation is observed. Likewise, by co-cultivating nestin-positive rMSC with NSC derived from green mouse, heterogenous spheres were obtained. When those heterogenous spheres are placed on polyornithine-coated surfaces, a differentiation of some rMSC into GFAP-positive cells occurs. These results indicate that nestin expression might be a pre-requisite for the acquisition by rMSC of the capacity to differentiate into some neural cell types. [less ▲]

Detailed reference viewed: 88 (3 ULg)
Full Text
Peer Reviewed
See detailNestin-positive mesenchymal stem cells favour the astroglial lineage in neural progenitors and stem cells by releasing active BMP4.
Wislet-Gendebien, Sabine ULg; Bruyere, Françoise ULg; Hans, Grégory ULg et al

in BMC Neuroscience (2004), 5

BACKGROUND: Spontaneous repair is limited after CNS injury or degeneration because neurogenesis and axonal regrowth rarely occur in the adult brain. As a result, cell transplantation has raised much ... [more ▼]

BACKGROUND: Spontaneous repair is limited after CNS injury or degeneration because neurogenesis and axonal regrowth rarely occur in the adult brain. As a result, cell transplantation has raised much interest as potential treatment for patients with CNS lesions. Several types of cells have been considered as candidates for such cell transplantation and replacement therapies. Foetal brain tissue has already been shown to have significant effects in patients with Parkinson's disease. Clinical use of the foetal brain tissue is, however, limited by ethical and technical problems as it requires high numbers of grafted foetal cells and immunosuppression. Alternatively, several reports suggested that mesenchymal stem cells, isolated from adult bone marrow, are multipotent cells and could be used in autograft approach for replacement therapies. RESULTS: In this study, we addressed the question of the possible influence of mesenchymal stem cells on neural stem cell fate. We have previously reported that adult rat mesenchymal stem cells are able to express nestin in defined culture conditions (in the absence of serum and after 25 cell population doublings) and we report here that nestin-positive (but not nestin-negative) mesenchymal stem cells are able to favour the astroglial lineage in neural progenitors and stem cells cultivated from embryonic striatum. The increase of the number of GFAP-positive cells is associated with a significant decrease of the number of Tuj1- and O4-positive cells. Using quantitative RT-PCR, we demonstrate that mesenchymal stem cells express LIF, CNTF, BMP2 and BMP4 mRNAs, four cytokines known to play a role in astroglial fate decision. In this model, BMP4 is responsible for the astroglial stimulation and oligodendroglial inhibition, as 1) this cytokine is present in a biologically-active form only in nestin-positive mesenchymal stem cells conditioned medium and 2) anti-BMP4 antibodies inhibit the nestin-positive mesenchymal stem cells conditioned medium inducing effect on astrogliogenesis. CONCLUSIONS: When thinking carefully about mesenchymal stem cells as candidates for cellular therapy in neurological diseases, their effects on resident neural cell fate have to be considered. [less ▲]

Detailed reference viewed: 75 (3 ULg)
Full Text
Peer Reviewed
See detailNéstor Ponce. Memorias y cicatrices.
Vanden Berghe, Kristine ULg

in Caravelle : Cahiers du Monde Hispanique et Luso-Bresilien (2012), 99

Detailed reference viewed: 14 (1 ULg)
Full Text
Peer Reviewed
See detailThe net biome production of full crop rotations in Europe
Kutsch, W. L.; Aubinet, Marc ULg; Buchmann, N. et al

in Agriculture, Ecosystems & Environment (2010), 139

Detailed reference viewed: 28 (7 ULg)
Full Text
Peer Reviewed
See detailNet ecosystem metabolism in a micro-tidal estuary (Randers Fjord, Denmark): evaluation of methods
Gazeau, Frédéric; Borges, Alberto ULg; Barrón, Cristina et al

in Marine Ecology. Progress Series (2005), 301

The metabolic status, the difference between organic matter production and consumption of an estuary (Randers Fjord, Denmark) has been assessed based on 2 field cruises in April and August 2001 and a ... [more ▼]

The metabolic status, the difference between organic matter production and consumption of an estuary (Randers Fjord, Denmark) has been assessed based on 2 field cruises in April and August 2001 and a number of approaches: (1) the oxygen (02) incubation method, (2) dissolved inorganic carbon (DIC) budgets, (3) the response surface difference (RSD) method based on diel O-2 changes and (4) land-ocean interaction in the coastal zone (LOICZ) budgets based on dissolved inorganic phosphorus (DIP). Although each method has its own associated limitations and uncertainties, the above approaches converged most of the time in consistent metabolic estimates, both in sign and magnitude, and revealed that this system was near metabolic balance in spring (net ecosystem production: NEP similar to 0) and net heterotrophic in summer (NEP similar to -50 mmol C m(-2) d(-1)). In this shallow estuary (mean depth = 1.6 m), the benthic compartment was very active and represented 70 and 30% of the total gross primary production in April and August, respectively. NEP rates measured during this study are in the range of previously reported rates in estuaries. [less ▲]

Detailed reference viewed: 60 (5 ULg)
Full Text
Peer Reviewed
See detailNet ecosystem production and carbon dioxide fluxes in the Scheldt estuarine plume
Borges, Alberto ULg; Ruddick, Kevin; Schiettecatte, Laure-Sophie et al

in BMC Ecology (2008), 8(15),

Background A time series of 4 consecutive years of measurements of the partial pressure of CO2 (pCO2) in the Scheldt estuarine plume is used here to estimate net ecosystem production (NEP). Results NEP in ... [more ▼]

Background A time series of 4 consecutive years of measurements of the partial pressure of CO2 (pCO2) in the Scheldt estuarine plume is used here to estimate net ecosystem production (NEP). Results NEP in the Scheldt estuarine plume is estimated from the temporal changes of dissolved inorganic carbon (DIC). The strong seasonal variations of NEP are consistent with previous reports on organic carbon dynamics in the area. These variations are related to successive phytoplankton blooms that partly feed seasonally variable heterotrophy the rest of the year. On an annual time scale the Scheldt estuarine plume behaves as a net heterotrophic system sustained with organic carbon input from the Scheldt inner estuary and the Belgian coast. During one of the years of the time-series the estuarine plume behaved annually as a net autotrophic system. This anomalous ecosystem metabolic behaviour seemed to result from a combination of bottom-up factors affecting the spring phytoplankton bloom (increased nutrient delivery and more favourable incoming light conditions). This net autotrophy seemed to lead to a transient aa accumulation of organic carbon, most probably in the sediments, that fed a stronger heterotrophy the following year. Conclusion The present work highlights the potential of using pCO2 data to derive detailed seasonal estimates of NEP in highly dynamic coastal environments. These can be used to determine potential inter-annual variability of NEP due to natural climatic oscillations or due to changes in anthropogenic impacts. [less ▲]

Detailed reference viewed: 47 (2 ULg)
Full Text
Peer Reviewed
See detailNet zero energy building: a review of current definitions and definition development in Belgium
Attia, Shady ULg; Mlecnik, Erwin; Van Loon, Stefan

in Proceedings of Passive House 2011 (2011, October 07)

The recast of the European Performance of Buildings Directive (EPBD) requires the uptake of a definition of so called ‘nearly zero energy’ buildings (nZEB). Belgium was first to set a definition for a ... [more ▼]

The recast of the European Performance of Buildings Directive (EPBD) requires the uptake of a definition of so called ‘nearly zero energy’ buildings (nZEB). Belgium was first to set a definition for a ‘net zero energy house’ (NZEB) in 2009. Every year the definition is revised for consistency with shortcomings and emerging issues. The Belgian definition raised many questions regarding (1) the net balance, (2) the application and calculation method (3) the indoor air quality and comfort, (4) energy use included in the balance, (5) the type of buildings, (6) the accepted renewable energy supply options, (7) the quality assurance and monitoring and (8) energy storage and the connection to the energy infrastructure. Therefore, the paper presents a review on the current Belgian definition and its market status in comparison with the international context. The aim of the paper is to review current definition discussions and pave the way to a more consistent definition. [less ▲]

Detailed reference viewed: 9 (1 ULg)
Full Text
Peer Reviewed
See detailNetamines H-N, Tricyclic Alkaloids from the Marine Sponge Biemna laboutei and Their Antimalarial Activity.
Gros, Emmanuelle; Al-Mourabit, Ali; Martin, Marie-Therese et al

in Journal of natural products (2014), 77(4), 818-23

Chemical examination of the CH2Cl2-MeOH (1:1) extract of the Madagascar sponge Biemna laboutei resulted in the isolation of seven new tricyclic alkaloids, netamines H-N (1-7), along with the known ... [more ▼]

Chemical examination of the CH2Cl2-MeOH (1:1) extract of the Madagascar sponge Biemna laboutei resulted in the isolation of seven new tricyclic alkaloids, netamines H-N (1-7), along with the known netamine G and mirabilins A, C, and F. Their structures were elucidated by interpretation of 1D and 2D NMR spectra and HRESIMS data. All compounds were evaluated for their cytotoxicity against KB cells and their antiplasmodial activity. Netamine M (6) was found to be cytotoxic, with an IC50 value in the micromolar range, and netamine K (4) exhibited activity against Plasmodium falciparum with an IC50 value of 2.4 muM. [less ▲]

Detailed reference viewed: 7 (1 ULg)
Full Text
Peer Reviewed
See detailNetherton’s syndrome in two sisters. A ten year experience of therapy with retinoids
Groves, S.; Dezfoulian, Bita ULg; Bonardeaux, Ch et al

in Journal of the European Academy of Dermatology & Venereology (1995)

Netherton’s syndrome is a recessive autosomal disease associating ichthyosiform dermatosis, hair dysplasia and systemic involvement. (Netherton, 1958, Arch. Dermatol., Vol. 78,483-487). We report the ... [more ▼]

Netherton’s syndrome is a recessive autosomal disease associating ichthyosiform dermatosis, hair dysplasia and systemic involvement. (Netherton, 1958, Arch. Dermatol., Vol. 78,483-487). We report the observation of two sisters who present the complete form of Netherton’s syndrome. Both patients were treated with retinoids for more than ten years. [less ▲]

Detailed reference viewed: 32 (15 ULg)
See detailThe Netlander Ionosphere and Geodesy Experiment
Barriot, Jean-Pierre; Dehant, Véronique; Folkner, W. et al

Conference (2001)

Detailed reference viewed: 10 (0 ULg)
Full Text
Peer Reviewed
See detailThe NETLANDER Ionosphere and Geodesy Experiment
Barriot, Jean-Pierre; Dehant, Véronique; Folkner, W. et al

in Advances in Space Research (2001), 28(8), 1237-1249

Detailed reference viewed: 12 (3 ULg)
See detailNetlander Ionospheric TEC Experiment
Cerisier, Jean-Claude; Axford, W. I.; Paëtzold, M. et al

Conference (1998)

Detailed reference viewed: 8 (0 ULg)
Full Text
Peer Reviewed
See detailNetrin-1 Mediates Early Events in Pancreatic Adenocarcinoma Progression, Acting on Tumor and Endothelial Cells.
Dumartin, L.; Quemener, C.; Laklai, H. et al

in Gastroenterology (2010), 138(4), 1595-606

BACKGROUND & AIMS: Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers. It is characterized by substantial tumor cell invasion and early-stage metastasis. We developed an in vivo ... [more ▼]

BACKGROUND & AIMS: Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers. It is characterized by substantial tumor cell invasion and early-stage metastasis. We developed an in vivo model to analyze interactions between cancer and stromal cells during early stages of PDAC. METHODS: Human pancreatic adenocarcinoma cells were grafted onto the chick chorioallantoic membrane (CAM). Human and chicken GeneChips were used simultaneously to study gene regulation during PDAC cell invasion. Bioinformatic analysis was used to identify human orthologs and cell specificity of gene expression. The effects of netrin-1 encoded by NTN1 were investigated in adhesion, invasion, and apoptosis assays. The effects of NTN1 silencing with small interfering RNAs were investigated in PDAC cells in vivo. NTN1 expression was measured in human PDAC samples. RESULTS: PDAC cells rapidly invade the CAM stroma and remodel the CAM vasculature. More than 870 stromal genes were up-regulated by >2-fold; the angiogenesis regulators vascular endothelial growth factor D, thrombospondin 1, and CD151 were among the most highly regulated genes. Silencing of tumor cell NTN1, which is up-regulated 4-fold in the PDAC model, inhibited tumor cell invasion in vivo. Netrin-1 conferred apoptosis resistance to tumor and endothelial cells in vitro, induced their invasion, and provided an adhesive substrate for tumor cells. NTN1 and its gene product are strongly overexpressed in human PDAC samples. CONCLUSIONS: We developed a useful tool to study the invasive mechanisms of early-stage PDAC. Netrin-1 might be an important regulator of pancreatic tumor growth that functions in tumor and endothelial cells. [less ▲]

Detailed reference viewed: 53 (7 ULg)
Full Text
Peer Reviewed
See detailNetwork design model for intermodal transport: the case of the hinterland of the Port of Cotonou
Lihoussou, Messan ULg; Limbourg, Sabine ULg

in ILS 2012 Proceeding (2012, August 27)

Since 2006, the Millennium Challenge Account program subsidizes a project to improve the performance of the Port of Cotonou, through modernization of infrastructure and management systems, and ... [more ▼]

Since 2006, the Millennium Challenge Account program subsidizes a project to improve the performance of the Port of Cotonou, through modernization of infrastructure and management systems, and strengthening institutional reforms. But the project mainly concerns the port, not the development of its hinterland. However, no port can develop without its links with its hinterland. That’s why we analyse the issues relating to the hinterland transport network. Both rail and road transportation networks will be examined. We also investigate inland terminals in order to build up intermodal transportation which is almost non-operational. Thus, the objective of this paper is to determine the optimal number and locations of the terminals so that the total costs of the distribution network are minimized. [less ▲]

Detailed reference viewed: 44 (1 ULg)
Full Text
Peer Reviewed
See detailNetwork Distance Prediction Based on Decentralized Matrix Factorization
Liao, Yongjun ULg; Geurts, Pierre ULg; Leduc, Guy ULg

in Lecture Notes in Computer Science (2010, May 11), 6091

Network Coordinate Systems (NCS) are promising techniques to predict unknown network distances from a limited number of measurements. Most NCS algorithms are based on metric space embedding and suffer ... [more ▼]

Network Coordinate Systems (NCS) are promising techniques to predict unknown network distances from a limited number of measurements. Most NCS algorithms are based on metric space embedding and suffer from the inability to represent distance asymmetries and Triangle Inequality Violations (TIVs). To overcome these drawbacks, we formulate the problem of network distance prediction as guessing the missing elements of a distance matrix and solve it by matrix factorization. A distinct feature of our approach, called Decentralized Matrix Factorization (DMF), is that it is fully decentralized. The factorization of the incomplete distance matrix is collaboratively and iteratively done at all nodes with each node retrieving only a small number of distance measurements. There are no special nodes such as landmarks nor a central node where the distance measurements are collected and stored. We compare DMF with two popular NCS algorithms: Vivaldi and IDES. The former is based on metric space embedding, while the latter is also based on matrix factorization but uses landmarks. Experimental results show thatDMF achieves competitive accuracy with the double advantage of having no landmarks and of being able to represent distance asymmetries and TIVs. [less ▲]

Detailed reference viewed: 126 (16 ULg)
Full Text
Peer Reviewed
See detailNetwork Fingerprinting: TTL-Based Router Signatures
Vanaubel, Yves ULg; Pansiot, Jean-Jacques; Mérindol, Pascal et al

in ACM/USENIX Internet Measurement Conference (2013, October)

Fingerprinting networking equipment has many potential applications and benefits in network management and security. More generally, it is useful for the understanding of network structures and their ... [more ▼]

Fingerprinting networking equipment has many potential applications and benefits in network management and security. More generally, it is useful for the understanding of network structures and their behaviors. In this paper, we describe a simple fingerprinting mechanism based on the initial TTL values used by routers to reply to various probing messages. We show that main classes obtained using this simple mechanism are meaningful to distinguish routers platforms. Besides, it comes at a very low additional cost compared to standard active topology discovery measurements. As a proof of concept, we apply our method to gain more insight on the behavior of MPLS routers and to, thus, more accurately quantify their visible/invisible deployment. [less ▲]

Detailed reference viewed: 133 (29 ULg)
Peer Reviewed
See detailA network for agricultural information technology : systems available in Belgium
Claustriaux, Jean-Jacques ULg

in Houseman, C. I. (Ed.) Agriculture - The establishment of a network for agricultural information technology (1990)

Detailed reference viewed: 13 (1 ULg)