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See detailDynamics and three-dimensional localization of ribosomal RNA within the nucleolus.
Thiry, Marc ULg; Cheutin, T.; O'Donohue, M. F. et al

in RNA (New York, N.Y.) (2000), 6(12), 1750-61

Although rRNA synthesis, maturation, and assembly into preribosomal particles occur within the nucleolus, the route taken by pre-rRNAs from their synthetic sites toward the cytoplasm remains largely ... [more ▼]

Although rRNA synthesis, maturation, and assembly into preribosomal particles occur within the nucleolus, the route taken by pre-rRNAs from their synthetic sites toward the cytoplasm remains largely unexplored. Here, we employed a nondestructive method for the incorporation of BrUTP into the RNA of living cells. By using pulse-chase experiments, three-dimensional image reconstructions of confocal optical sections, and electron microscopy analysis of ultrathin sections, we were able to describe topological and spatial dynamics of rRNAs within the nucleolus. We identified the precise location and the volumic organization of four typical subdomains, in which rRNAs are successively moving towards the nucleolar periphery during their synthesis and processing steps. The incorporation of BrUTP takes place simultaneously within several tiny spheres, centered on the fibrillar centers. Then, the structures containing the newly synthesized RNAs enlarge and appear as compact ringlets disposed around the fibrillar centers. Later, they form hollow spheres surrounding the latter components and begin to fuse together. Finally, these structures widen and form large rings reaching the limits of the nucleoli. These results clearly show that the transport of pre-rRNAs within the nucleolus does not occur randomly, but appears as a radial flow starting from the fibrillar centers that form concentric rings, which finally fuse together as they progress toward the nucleolar periphery. [less ▲]

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See detailDynamics Characterization of Fully Hydrated Bacterial Cell Walls by Solid-State NMR: Evidence for Cooperative Binding of Metal Ions
Kern, Thomas; Giffard, Mathilde; Hediger, Sabine et al

in Journal of the American Chemical Society (2010), 132

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See detailDynamics in mangroves assessed by high-resolution and multi-temporal satellite data: a case study in Zhanjiang Mangrove National Nature Reserve (ZMNNR), P. R. China
Leempoel, K; Satyaranayana, B; Bourgeois, C et al

in Biogeosciences Discussions (2013), 10

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See detailDynamics in miscible blends of polystyrene and poly(vinyl methyl ether)
Pathak, J. A.; Colby, R. H.; Floudas, G. et al

in Macromolecules (1999), 32(8), 2553-2561

We report results on the linear viscoelasticity (oscillatory shear in the temperature range Tg (glass-transition temperature) ≤ T ≤ Tg + 90 K) of miscible blends of polystyrene (PS) and poly(vinyl methyl ... [more ▼]

We report results on the linear viscoelasticity (oscillatory shear in the temperature range Tg (glass-transition temperature) ≤ T ≤ Tg + 90 K) of miscible blends of polystyrene (PS) and poly(vinyl methyl ether) (PVME) and segmental relaxations, measured by dielectric spectroscopy. The Flory−Huggins interaction parameter of this blend is weakly negative, and the glass transitions of the pure components are quite disparate (ΔTg = 125 K). PS/PVME blends have been found to be consistently thermorheologically complex at both the segmental and terminal levels: the empirical time−temperature superposition (tTS) principle applies to neither their oscillatory shear response nor their dielectric response. Using the tube model, we quantitatively compare dielectric and mechanical results. At low temperatures, the effective time scale for motion of a Kuhn segment (the shortest Rouse mode) is near the long-time end of the distribution of segmental relaxation times of PVME, in both the pure and blended states. The slowest relaxing segments thus control the longer-time relaxation processes of the chains. Miscible blends with weak interactions and large ΔTg have concentration fluctuations that broaden the distribution of segmental relaxation times. This distribution narrows as the temperature is raised in the blend, leading to the failure of tTS for terminal dynamics. [less ▲]

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See detailDynamics of a bouncing dimer
Dorbolo, Stéphane ULg; Volfson, D.; Tsimring, L. et al

in Physical Review Letters (2005), 95(4),

We investigate the dynamics of a dimer bouncing on a vertically oscillated plate. The dimer, composed of two spheres rigidly connected by a light rod, exhibits several modes depending on initial and ... [more ▼]

We investigate the dynamics of a dimer bouncing on a vertically oscillated plate. The dimer, composed of two spheres rigidly connected by a light rod, exhibits several modes depending on initial and driving conditions. The first excited mode has a novel horizontal drift in which one end of the dimer stays on the plate during most of the cycle, while the other end bounces in phase with the plate. The speed and direction of the drift depend on the aspect ratio of the dimer. We employ event-driven simulations based on a detailed treatment of frictional interactions between the dimer and the plate in order to elucidate the nature of the transport mechanism in the drift mode. [less ▲]

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See detailDynamics of a bouncing droplet onto a vertically vibrated interface
Gilet, Tristan ULg; Terwagne, Denis ULg; Vandewalle, Nicolas ULg et al

in Physical Review Letters (2008), 100(16),

Low viscosity (< 100 cSt) silicon oil droplets are placed on a high viscosity (1000 cSt) oil bath that vibrates vertically. The viscosity difference ensures that the droplet is more deformed than the bath ... [more ▼]

Low viscosity (< 100 cSt) silicon oil droplets are placed on a high viscosity (1000 cSt) oil bath that vibrates vertically. The viscosity difference ensures that the droplet is more deformed than the bath interface. Droplets bounce periodically on the bath when the acceleration of its sinusoidal motion is larger than a threshold value. The threshold is minimum for a particular frequency of excitation: droplet and bath motions are in resonance. The bouncing droplet has been modeled by considering the deformation of the droplet and the lubrication force exerted by the air layer between the droplet and the bath. Threshold values are predicted and found to be in good agreement with our measurements. [less ▲]

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See detailDynamics of a grain-filled ball on a vibrating plate
Pacheco-Vazquez, felipe; Ludewig, François ULg; Dorbolo, Stéphane ULg

in Physical Review Letters (2014), 113

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See detailDynamics of a Strongly Nonlinear Spacecraft Structure Part I: Experimental Identification
Noël, Jean-Philippe ULg; Renson, Ludovic ULg; Kerschen, Gaëtan ULg

in Proceedings of the 13th European Conference on Spacecraft Structures, Materials and Environmental Testing (2014, April)

The present paper addresses the identification of a real-life spacecraft structure possessing a strongly nonlinear component with multiple mechanical stops. The complete identification procedure, from ... [more ▼]

The present paper addresses the identification of a real-life spacecraft structure possessing a strongly nonlinear component with multiple mechanical stops. The complete identification procedure, from nonlinearity detection and characterization to parameter estimation, is carried out based upon experimental sine-sweep data collected during a classical spacecraft qualification campaign. [less ▲]

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See detailDynamics of a Strongly Nonlinear Spacecraft Structure Part II: Modal Analysis
Renson, Ludovic ULg; Noël, Jean-Philippe ULg; Kerschen, Gaëtan ULg

in Proceedings of the 13th European Conference on Spacecraft Structures, Materials & Environmental Testing (2014, April)

The present paper investigates the dynamics of a real-life spacecraft structure possessing a strongly nonlinear component with multiple mechanical stops. A full-scale finite element model is built for ... [more ▼]

The present paper investigates the dynamics of a real-life spacecraft structure possessing a strongly nonlinear component with multiple mechanical stops. A full-scale finite element model is built for gaining additional insight into the nonlinear dynamics that was observed experimentally in a companion paper (Part I). To this end, advanced techniques and theoretical concepts such as numerical continuation and nonlinear normal modes are exploited. [less ▲]

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See detailDynamics of Agrarian Systems in Hai Duong Province, North Vietnam
Han Quang, Hanh ULg

Doctoral thesis (2013)

In Vietnam, the agrarian systems have evolved considerably during the socio-economic transformation period initiated in the late 1980s with the political reform (Doi Moi). In a region around the capital ... [more ▼]

In Vietnam, the agrarian systems have evolved considerably during the socio-economic transformation period initiated in the late 1980s with the political reform (Doi Moi). In a region around the capital, where the process of industrialization, urbanization, and international integration has been accelerating, a number of questions about the sustainability of agrarian systems are raising. By diagnosing and analysing the dynamics of agrarian systems from 1980 to 2010, this study aims to provide decision-makers with some sectorial and territorial policy options authorizing the sustainable development of agriculture and rural society in the new socio-economic context. Combining the historical, adaptive, and systematic approaches, this study shows that farmers in Hai Duong province adapted effectively to the socio-economic and institutional changes, notably by transforming part of the rice land areas into other agricultural land use purposes such as fish ponds, animal buildings, vegetable fields and fruit orchards. These rapid changes, however, do not go in the direction of improving the sustainability of agrarian systems. Farm holders are now facing with many technical and economic contradictions whereas land issues are not only related to the agricultural purposes. Competition functions in land use, fragmentation of plots, the imperfection of the land market and rising property values are all emerging. The prospects for sustainability of agrarian systems are analysed under different scenarios which highlight the complexity of policy options. The recommendations are made not only for the agricultural sector in general, but also for different agrarian systems in specific regions. [less ▲]

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See detailDynamics of black-grass populations depending on the sowing time of winter wheat
Vandersteen, Joëlle; Jaunard, Delphine ULg; Mahy, Grégory ULg et al

in Communications in Agricultural and Applied Biological Sciences (2011, May 24), 76(3), 485-490

Currently, economic, agronomic and environmental concerns, lead to reduce use of herbicides. This reduction can be help by cultural measures like delay of the sowing date. Four sowing dates of winter ... [more ▼]

Currently, economic, agronomic and environmental concerns, lead to reduce use of herbicides. This reduction can be help by cultural measures like delay of the sowing date. Four sowing dates of winter wheat from 15th of October to 26th of November were tested. Dynamic of black-grass populations and their reproduction rate were assessed as well as dynamic of winter wheat for each date. Delay of sowing could significantly reduce reproduction rate of blac-grass. It was shwn that the emergence rate (pl/m²), but also number of ears per plant and number of seeds per ear of black-grass decreased significantly with the sowing date. This reproduction of seeds productioin already is from sixty per cent of a delay of two weeks sowing. [less ▲]

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See detailThe Dynamics of Complex Formation between Amylose Brushes on Gold and Fatty Acids by QCM‐D
Cao, Zheng; Tsoufis, Theodoros; Svaldo Lanero, Tiziana ULg et al

in Biomacromolecules (2013), 14

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See detailDynamics of complex molecular systems with numerical kinetic energy operators in generalized coordinates
Lauvergnat, David; Baloitcha, Ezinvi; Dive, Georges ULg et al

in Chemical Physics (2006), 326(2-3), 500-508

Dynamics of complex molecular systems in generalized coordinates (q,p) using numerical kinetic energy operators is investigated. The kinematical tools necessary for quantum, classical or semiclassical ... [more ▼]

Dynamics of complex molecular systems in generalized coordinates (q,p) using numerical kinetic energy operators is investigated. The kinematical tools necessary for quantum, classical or semiclassical dynamics with or without constraints mainly come from the covariant and contravariant components of the metric tensor and their derivatives up to the second ones. These quantities are computed numerically but without any other approximation than the numerical precision by the code TNUM. This code generates kinetic energy operators in the internal coordinates of the Z-matrix describing the molecular frame geometry in the ab initio quantum chemistry step or in symmetry adapted coordinates [D. Lauvergnat, A. Nauts, J. Chem. Phys. 116 (2002) 8560]. Various reduced dimensionality models can be used in the upgraded code. The interface with an ab initio code is calibrated on a 22-atom system for which a two-dimensional quantum treatment with a constrained Hamiltonian has been carried out previously. The test application concerns the spreading properties of a wave packet in an unstable flat region around a valley ridge inflexion point between two transition states in the Endo-dimerization of cyclopentadiene. We perform here on-the-fly classical or semiclassical dynamics in full or reduced dimensionality. (c) 2006 Elsevier B.V. All rights reserved. [less ▲]

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See detailDynamics of copepod faecal pellets in relation to a Phaeocystis dominated phytoplankton bloom: characteristics, production and flux
Frangoulis, Costa; Belkhiria, Sami; Goffart, Anne ULg et al

in Journal of Plankton Research (2001), 23(1), 75-88

Copepod faecal pellet characteristics and production were measured in spring 1995, 1996 and 1997 in the North Sea Southern Bight in order to define changes due to the development of the phytoplankton ... [more ▼]

Copepod faecal pellet characteristics and production were measured in spring 1995, 1996 and 1997 in the North Sea Southern Bight in order to define changes due to the development of the phytoplankton bloom. Changes were related to the succession from diatoms to a Phaeocystis sp. bloom. Mean monthly pellet production decreased during the Phaeocystis bloom development to 0.27 pellets ind. –1 h –1, approximately 80% lower than before and after the bloom. Although phytoplanktonic pigments showed significant differences between inshore and offshore stations, there was no such significant difference for faecal pellet production. Faecal pellet sinking-rate decreased from 100 to 70 m day –1 during the transition from a diatom- to a Phaeocystis-dominated bloom. This was due to a decrease in pellet density and/or a decrease of the pellet volume. These results supported the idea of lower feeding of copepods under Phaeocystis bloom conditions. As mean seasonal density of copepod faecal pellets was higher (1.37 g cm –3) than in other seas, accidental ingestion of sedimentary material as the cause of this high density is discussed. [less ▲]

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See detailDynamics of crack opening in a one-dimensional desiccation experiment
Lecocq, N.; Vandewalle, Nicolas ULg

in Physica A: Statistical Mechanics and its Applications (2003), 321(3-4), 431-441

We used a simple one-dimensional experiment to investigate the dynamical aspects of crack opening that occurs in clay exposed to shrinkage induced by desiccation. The opening rate of single cracks is ... [more ▼]

We used a simple one-dimensional experiment to investigate the dynamical aspects of crack opening that occurs in clay exposed to shrinkage induced by desiccation. The opening rate of single cracks is obtained. A simple model is introduced to account for the observed behavior. Interaction between adjacent cracks is put into evidence and a collective behavior is observed. (C) 2002 Elsevier Science B.V. All rights reserved. [less ▲]

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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)

Detailed reference viewed: 14 (1 ULg)