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
Full Text
Peer Reviewed
See detailLight modulation of human sleep depends on a polymorphism in the clock gene Period3.
Chellappa, Sarah Laxhmi ULg; Viola, Antoine U.; Schmidt, Christina ULg et al

in Behavioural Brain Research (2014), 271

Non-image-forming (NIF) responses to light powerfully modulate human physiology. However, it remains scarcely understood how NIF responses to light modulate human sleep and its EEG hallmarks, and if there ... [more ▼]

Non-image-forming (NIF) responses to light powerfully modulate human physiology. However, it remains scarcely understood how NIF responses to light modulate human sleep and its EEG hallmarks, and if there are differences across individuals. Here we investigated NIF responses to light on sleep in individuals genotyped for the PERIOD3 (PER3) variable-number tandem-repeat (VNTR) polymorphism. Eighteen healthy young men (20-28 years; mean+/-SEM: 25.9+/-1.2) homozygous for the PER3 polymorphism were matched by age, body-mass index, and ethnicity. The study protocol comprised a balanced cross-over design during the winter, during which participants were exposed to either light of 40lx at 6500K (blue-enriched) or light at 2500K (non-blue enriched), during 2h in the evening. Compared to light at 2500K, light at 6500K induced a significant increase in all-night NREM sleep slow-wave activity (SWA: 1.0-4.5Hz) in the occipital cortex for PER3(5/5) individuals, but not for PER3(4/4) volunteers. Dynamics of SWA across sleep cycles revealed increased occipital NREM sleep SWA for virtuallyall sleep episode only for PER3(5/5) individuals. Furthermore, they experienced light at 6500K as significantly brighter. Intriguingly, this subjective perception of brightness significantly predicted their increased occipital SWA throughout the sleep episode. Our data indicate that humans homozygous for the PER3(5/5) allele are more sensitive to NIF light effects, as indexed by specific changes in sleep EEG activity. Ultimately, individual differences in NIF light responses on sleep may depend on a clock gene polymorphism involved in sleep-wake regulation. [less ▲]

Detailed reference viewed: 36 (2 ULg)
Full Text
Peer Reviewed
See detailLight reflection model for lighting applications
Embrechts, Jean-Jacques ULg

in Lighting Research & Technology (1995), 27(4)

Detailed reference viewed: 26 (5 ULg)
Full Text
Peer Reviewed
See detailLight Response of Seedlings of a Central African Timber Tree Species, Lophira alata (Ochnaceae), and the Definition of Light Requirements
Biwolé, Achille Bernard; Daïnou, Kasso ULg; Fayolle, Adeline ULg et al

in Biotropica (2015), 47(6), 681-688

Light is of primary importance in structuring tropical tree communities. Light exposure at seedling and adult stages has been used to characterize the ecological profile of tropical trees, with many ... [more ▼]

Light is of primary importance in structuring tropical tree communities. Light exposure at seedling and adult stages has been used to characterize the ecological profile of tropical trees, with many implications in forest management and restoration ecology. Most shadetolerance classification systems have been proposed based on empirical observations in a specific area and thus result in contradictions among categories assigned to a given species. In this study, we aimed to quantify the light requirements for seedling growth of a Central African timber tree, Lophira alata (Ochnaceae), taking into account effects of population origin. In two controlled experiments: a light response experiment and a comparative population experiment, conducted in southwestern Cameroon, using seeds collected from four populations (three from Cameroon and one from Gabon), we examined the quantitative responses to irradiance of seedlings. After 2 years, mortality was very low (<3%), even in extremely low irradiance. Growth and biomass allocation patterns varied in response to light, with intermediate irradiance (24–43%) providing optimal conditions. Light response differed between populations. The Boumba population in the northeastern edge of the species’ distribution exhibited the highest light requirements, suggesting a local adaptation. As a result of positive growth at low irradiance and maximum growth at intermediate irradiance, we concluded that L. alata exhibits characteristics of both non-pioneer and pioneer species. Implications of our results to propose an objective way to assign the light requirement for tropical tree species are discussed. [less ▲]

Detailed reference viewed: 27 (6 ULg)
Full Text
Peer Reviewed
See detailLight scattering by rough surfaces: Electromagnetic model for lighting simulations
Embrechts, Jean-Jacques ULg

in Lighting Research & Technology (1992), 24(4)

Detailed reference viewed: 18 (5 ULg)
Full Text
Peer Reviewed
See detailLight scattering properties of exopolysaccharide solutions.
Lespineux, David; Sevrin, Chantal ULg; Freitas, F et al

Poster (2009, April 01)

Detailed reference viewed: 26 (0 ULg)
Full Text
Peer Reviewed
See detailLight scattering study of salt-free "polyelectrolyte behaviour" of monotelechelic ionomers in a polar solvent
Kupperblatt, Gary; Hara, Masanori; Vanhoorne, Pierre ULg et al

in Polymer (1996), 37(16), 3741-3744

Salt-free polyelectrolyte behaviour which is typically observed at low polymer concentrations for polyelectrolyte aqueous solutions and random ionomer non-aqueous solutions (in polar solvents) (i.e ... [more ▼]

Salt-free polyelectrolyte behaviour which is typically observed at low polymer concentrations for polyelectrolyte aqueous solutions and random ionomer non-aqueous solutions (in polar solvents) (i.e., negative angular dependence of the reciprocal scattering in static light scattering and an appearance of the fast mode in dynamic light scattering) has been observed for monotelechelic ionomer solutions in a polar solvent. This indicates that only single charge (per chain) is sufficient to produce intermolecular electrostatic interactions, which are responsible for such characteristic behaviour. However, the 'characteristic' behaviour, which is typically observed at higher concentrations for polyelectrolyte and random ionomer solutions (i.e., large positive apparent radius of gyration in static scattering and appearance of the slow mode in addition to the fast mode in dynamic scattering) has not been observed to date for monotelechelic ionomer solutions. The absence of high-concentration characteristics for the monotelechelic ionomer solutions gives additional insight as to the nature and structure of 'heterogeneities' in salt-free polyelectrolyte solutions, which is still controversial. [less ▲]

Detailed reference viewed: 47 (3 ULg)
Full Text
Peer Reviewed
See detailThe light stress-induced protein ELIP2 is a regulator of chlorophyll synthesis in Arabidopsis thaliana
Tzvetkova-Chevolleau, T.; Franck, Fabrice ULg; Alawady, A. E. et al

in Plant Journal (The) (2007), 50(5), 795-809

The early light-induced proteins (ELIPs) belong to the multigenic family of pigment-binding light-harvesting complexes. ELIPs accumulate transiently and are believed to play a protective role in plants ... [more ▼]

The early light-induced proteins (ELIPs) belong to the multigenic family of pigment-binding light-harvesting complexes. ELIPs accumulate transiently and are believed to play a protective role in plants exposed to high levels of light. Constitutive expression of the ELIP2 gene in Arabidopsis resulted in a marked reduction of the pigment content of the chloroplasts, both in mature leaves and during greening of etiolated seedlings. The chlorophyll loss was associated with a decrease in the number of photosystems in the thylakoid membranes, but the photosystems present were fully assembled and functional. A detailed analysis of the chlorophyll-synthesizing pathway indicated that ELIP2 accumulation downregulated the level and activity of two important regulatory steps: 5-aminolevulinate synthesis and Mg-protoporphyrin IX (Mg-Proto IX) chelatase activity. The contents of glutamyl tRNA reductase and Mg chelatase subunits CHLH and CHLI were lowered in response to ELIP2 accumulation. In contrast, ferrochelatase activity was not affected and the inhibition of Heme synthesis was null or very moderate. As a result of reduced metabolic flow from 5-aminolevulinic acid, the steady state levels of various chlorophyll precursors (from protoporphyrin IX to protochlorophyllide) were strongly reduced in the ELIP2 overexpressors. Taken together, our results indicate that the physiological function of ELIPs could be related to the regulation of chlorophyll concentration in thylakoids. This seems to occur through an inhibition of the entire chlorophyll biosynthesis pathway from the initial precursor of tetrapyrroles, 5-aminolevulinic acid. We suggest that ELIPs work as chlorophyll sensors that modulate chlorophyll synthesis to prevent accumulation of free chlorophyll, and hence prevent photooxidative stress. [less ▲]

Detailed reference viewed: 46 (4 ULg)
Full Text
See detailLight transmission imaging as a useful tool to decrypt root water uptake
Lobet, Guillaume ULg; Javaux, M.; Pagès, L. et al

Poster (2009)

Detailed reference viewed: 17 (4 ULg)
See detailLight, alertness, cognition, and much more
Vandewalle, Gilles ULg

Scientific conference (2015, April 13)

Detailed reference viewed: 28 (0 ULg)
Full Text
Peer Reviewed
See detailThe light-front gauge-invariant energy-momentum tensor
Lorce, Cédric ULg

in Journal of High Energy Physics [=JHEP] (2015)

Detailed reference viewed: 20 (3 ULg)
Full Text
Peer Reviewed
See detailLight-front interpretation of Proton Generalized Polarizabilities
Gorchtein, M.; Lorce, Cédric ULg; Pasquini, B. et al

in Physical Review Letters (2010), 104

We extend the recently developed formalism to extract light-front quark charge densities from nucleon form factor data to the deformations of these quark charge densities when applying an external ... [more ▼]

We extend the recently developed formalism to extract light-front quark charge densities from nucleon form factor data to the deformations of these quark charge densities when applying an external electric field. We show that the resulting induced polarizations can be extracted from proton generalized polarizabilities. The available data for the generalized electric polarizability of the proton yield a pronounced structure in its induced polarization at large transverse distances, which will be pinned down by forthcoming high precision virtual Compton scattering experiments. [less ▲]

Detailed reference viewed: 17 (3 ULg)
Full Text
See detailLight-induced gas exchanges in shortly illuminated intact etiolated leaves measured by mass spectrometry
Franck, Fabrice ULg; Peltier, Gilles

in Colloque de Photosynthèse (1986)

Detailed reference viewed: 12 (2 ULg)
Full Text
Peer Reviewed
See detailLight-induced Hetero-Diels Alder cycloaddition as a new coupling method to biomolecule radiolabeling
Dammicco, Sylvestre ULg; Luxen, André ULg; Thonon, David et al

Poster (2013, May 16)

The formation of a C-18F bond requires hard conditions which is problematic for the biomolecule radiolabelling. The alternative method which has been developed since a few decades consists in ... [more ▼]

The formation of a C-18F bond requires hard conditions which is problematic for the biomolecule radiolabelling. The alternative method which has been developed since a few decades consists in incorporating the 18F on a prosthetic group and coupling it to the biomolecule. The copper (I)-catalysed 1,2,3-triazole formation involving azides and terminal alkynes is a powerful and rapid method of coupling but present the inconvenient of the employment of cytotoxic reagents. The photoclick conjugation is a promising alternative with no need of catalyst[1]. Recently, a light-induced hetero-Diels Alder cycloaddition involving a 3-(hydroxymethyl)-2-naphthol derivative and an electron-rich olefin has been developed[2]. This reaction seems well adapted for the fast conjugation of radionuclides to biomolecules. Herein we report the synthesis of a [18F]fluoronaphtoquinone derivative as prosthetic group and its reaction with vinyl ethers. [less ▲]

Detailed reference viewed: 77 (21 ULg)
Full Text
Peer Reviewed
See detailLight-induced quenching of photosystem II fluorescence at 77 K
Kyle, D. J.; Arntzen, C. J.; Franck, Fabrice ULg et al

in Photochemistry & Photobiology (1983), 38

Light-induced quenching of the low temperature fluorescence emission from photosystem II (PS II) at 695 nm (F695) has been observed in chloroplasts and whole leaves of spinach. Photosystem I (PS I ... [more ▼]

Light-induced quenching of the low temperature fluorescence emission from photosystem II (PS II) at 695 nm (F695) has been observed in chloroplasts and whole leaves of spinach. Photosystem I (PS I) fluorescence emission at 735 nm (F735) is quenched to a lesser degree but this quenching is thought to originate from PS II and is manifest in a reduced amount of excitation energy available for spillover to PS I. Differential quenching of these two fluorescence emissions leads to an increase in the F735/F685 ratio on exposure to light at 77 K. Rewarming the sample from -196°C discharges the thermoluminescence Z-band and much of the original unquenched fluorescence is recovered. The relationship between the thermoluminescence Z-band and the quenching of the low temperature fluorescence emission (F695) is discussed with respect to the formation of reduced pheophytin in the PS II reaction center at 77 K. [less ▲]

Detailed reference viewed: 39 (2 ULg)
Full Text
Peer Reviewed
See detailLight-sensitive brain pathways and aging
Daneault, Véronique; Dumont, Marie; Massé, Eric et al

in Journal of Physiological Anthropology (2016), 35(9),

Detailed reference viewed: 18 (2 ULg)
Full Text
Peer Reviewed
See detailLight-to-moderate alcohol intake increases the risk of hepatocellular carcinoma in patients with HCV-related compensated cirrhosis: a prospective study.
Vandenbulcke, H; Moreno, C; Colle, I et al

in Acta Gastro-Enterologica Belgica (2016, March), 79(1), 01

Detailed reference viewed: 26 (2 ULg)
Peer Reviewed
See detailLIGHTWEIGHT CEMENTITIOUS MORTAR MADE WITH FOAMED PLASTIC WASTE AGGREGATES
Coppola, Bartolomeo ULg; Di Maio, Luciano; Courard, Luc ULg et al

in Durability and Sustainability of Concrete Structures – Workshop Proceedings, Bologna 1-3 October 2015 (2015)

In recent years the increasing interest for eco-sustainable building materials and the rising issue of plastic waste disposal are leading to the engineering of new composite construction materials ... [more ▼]

In recent years the increasing interest for eco-sustainable building materials and the rising issue of plastic waste disposal are leading to the engineering of new composite construction materials incorporating post consumer recycled plastics, able at the same time to meet new standard requirements, in terms of energy efficiency, and to reduce the consumption of natural resources. In the context of these issues, we have performed investigations on the effects of the addition of foamed artificial aggregates deriving from recycled plastic materials to a cementitious mortar. For this purpose, several mortar samples containing natural sand and different amounts (10, 25 and 50 % by volume) of foamed recycled plastic wastes were produced. The foaming of the recycled plastic waste was performed in laboratory by a foam extrusion process using a blowing agent (2 wt.%). An artificial aggregates particle size distribution similar to standard sand was used. Rheological and physical properties of lightweight mortar were studied. The improved surface roughness of foamed plastic aggregates ensures a more continuous interface and the presence of surface pores provides interlocking effect with cement paste. Replacement of natural sand by artificial aggregates produces a lightweight mortar but reduces mechanical properties. [less ▲]

Detailed reference viewed: 125 (44 ULg)