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See detailInteracting elementary excitations in ultrarelativistic plasmas: Damping mechanisms and plasma thermodynamics
Vanderheyden, Benoît ULg

Doctoral thesis (1998)

This dissertation examines the properties of the elementary excitations in quark-gluon and electromagnetic plasmas. Due to Debye screening and Landau damping mechanisms, the interaction fields fall off at ... [more ▼]

This dissertation examines the properties of the elementary excitations in quark-gluon and electromagnetic plasmas. Due to Debye screening and Landau damping mechanisms, the interaction fields fall off at large distances, except for static magnetic and color-magnetic fields. The lack of screening of the magnetic interaction leads to a singularity at small momentum transfer in the matrix element for fermion-fermion scattering via the exchange of a single gluon, or a single photon. We analyze the effects of this singularity on the quasiparticle lifetimes in plasmas at zero and at finite temperature T. First, at T = 0, we find that the fermion excitations above the ground state are long-lived, as the Pauli exclusion principle limits the collision phase space. Because the magnetic interaction is long-ranged, the damping rates of the excitations near the edge of the Fermi sea vary linearly with the excitation energy. The quasiparticles are therefore not as well- defined as those encountered in non-relativistic plasmas, with short-ranged interactions, where the variation of the damping rates away from the Fermi surface is quadratic, thus slower. Second, we find that in plasmas at finite temperatures, the magnetic interaction introduces correlations between the successive scatterings of the fermion quasiparticles on the charges in the system. This effect leads to a decay law that decreases in time more rapidly than an exponential; however the quasiparticles are long-lived. We also derive a framework for ascertaining the effects of the long-ranged magnetic interaction on the thermodynamic properties of relativistic plasmas. Our method generalizes the concept of conserving, Φ-derivable, approximations to relativistic field theories. By treating the interaction field as a dynamical degree of freedom, we are able to derive the thermodynamical potential in terms of full propagators. This approach allows us to resolve the entropy into contributions from its interacting elementary excitations. [less ▲]

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See detailInteracting surface of the receptor-binding domain.
Gatot, Jean-Stéphane; Callebaut, Isabelle; Van Lint, Carine et al

in Société Belge de Biochimie et de Biologie moléculaire. (2002, February 22)

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See detailInteracting winds in massive binaries
Rauw, Grégor ULg

in Pavlovski, Kresimir; Tkachenko, Andrew; Torres, Guillermo (Eds.) EAS Publications Series (2013, February 01)

Massive stars feature highly energetic stellar winds that interact whenever two such stars are bound in a binary system. The signatures of these interactions are nowadays found over a wide range of ... [more ▼]

Massive stars feature highly energetic stellar winds that interact whenever two such stars are bound in a binary system. The signatures of these interactions are nowadays found over a wide range of wavelengths, including the radio domain, the optical band, as well as X-rays and even γ-rays. A proper understanding of these effects is thus important to derive the fundamental parameters of the components of massive binaries from spectroscopic and photometric observations. [less ▲]

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See detailThe interaction between a protein and a ligand molecule studied by linear and non-linear optical spectroscopies
Dreesen, Laurent ULg; Méthivier, C.; Sartenaer, Y. et al

in Physical Chemical News (2007), 36

We use infrared reflection-adsorption (IRRAS) and sum-frequency generation (SFG) spectroscopies to study the interaction between a protein (avidin) and a ligand molecule (biocytin or its thiol derivative ... [more ▼]

We use infrared reflection-adsorption (IRRAS) and sum-frequency generation (SFG) spectroscopies to study the interaction between a protein (avidin) and a ligand molecule (biocytin or its thiol derivative) adsorbed on metals (Au and Ag) and insulators (CaF2 in two separate spectral ranges 2800-3500 cm-1 and 1400-1800 cm-1, respectively. No specific interaction is detected by SFG when the measurements are carried out on metals although IRRAS measurements attest the presence of a protein ad-layer. This is explained by the disordered character of the adsorbed film of avidin which is therefore SFG inactive. When the experiments are performed on an insulating substrate, no change of the biocytin/CaF2 SFG spectrum is detected in the low spectral range (1400-1800 cm-1) after immersion in an avidin solution in contrast with what was clearly demonstrated in the 2800-3500 cm-1 spectral range. Finally, we report, for the first time, the observation by SFG of the CH2 scissor vibration mode at 1465 cm-1. [less ▲]

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See detailInteraction between antimicrobial peptides and membranes
Deleu, Magali ULg

Conference (2004)

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See detailInteraction between Antitumor Drugs and a Double-Stranded Oligonucleotide Studied by Electrospray Ionization Mass Spectrometry
Gabelica, Valérie ULg; De Pauw, Edwin ULg; Rosu, Frédéric ULg

in Journal of Mass Spectrometry [=JMS] (1999), 34(12), 1328-1337

Electrospray ionization mass spectrometry was used to investigate the complex formation between a double-stranded oligonucleotide and various antitumor drugs belonging to two categories: intercalators ... [more ▼]

Electrospray ionization mass spectrometry was used to investigate the complex formation between a double-stranded oligonucleotide and various antitumor drugs belonging to two categories: intercalators (ethidium bromide, amsacrine and ascididemin) and minor groove binders (Hoechst 33258, netropsin, distamycin A, berenil and DAPI). The goal of this study was to determine whether the relative intensities in the mass spectra reflect the relative abundances of the species in the solution phase. The full-scan mass spectra suggest non-specific binding for the intercalators and specific binding for the minor groove binders. The preferential stoichiometries adopted by each minor groove binder were determined by studying the influence of the drug concentration on the spectra. We obtained 2:1 > 1:1 for distamycin, 1:1 > 2:1 for Hoechst 33258 and DAPI and only the 1 : 1 complex for netropsin and berenil. These features reflect their known behavior in solution. The compared tandem mass spectra of the 1 : 1 complexes with Hoechst 33258 and netropsin, when correlated with published crystallographic data, suggest the possibility of inferring some structural information. The relative binding affinities of the drug for the considered duplex were deduced with two by two competition experiments, assuming that the relative intensities reflect the composition of the solution phase. The obtained affinity scale is netropsin > distamycin A > DAPI > Hoechst 33258 > berenil. These examples show some of the potential uses of mass spectrometry as a useful tool for the characterization of specific drug binding to DNA, and possibly a rapid drug screening method requiring small amounts of materials. [less ▲]

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See detailInteraction between ascites susceptibility and CO during the second half of incubation of two broiler lines. Effect on embryonic development and hatching process.
Everaert, Nadia ULg; Debonne, M.; Willemsen, H. et al

in British poultry science (2010), 51(3), 335-43

1. Because CO(2) during the second half of incubation is known to influence air cell and blood gases, and embryo development, it is postulated that post-hatch development and ascites sensitivity could ... [more ▼]

1. Because CO(2) during the second half of incubation is known to influence air cell and blood gases, and embryo development, it is postulated that post-hatch development and ascites sensitivity could also be influenced. 2. An ascites susceptible (A) and an ascites resistant (E) broiler line were incubated under standard incubation or high CO(2) conditions (up to 4%) from embryonic day (ED) 10 onwards. The embryonic development and the hatching process of these two lines were compared when incubated under standard or high CO(2) conditions from over the second half of incubation. 3. The A line, selected for high post-hatch growth rate, exhibited a higher relative embryo weight from ED10 until ED16, which was supported by a higher air cell pCO(2), lower air cell pO(2), higher corticosterone and thyroid hormones and earlier hatching time. 4. Incubation under high CO(2) increased air cell pCO(2), retarded yolk consumption, and decreased glycogen concentration in the liver at hatch. Hatchability decreased in both lines when incubated under high CO(2), due to an increased late mortality of embryos that died before IP. 5. These results suggest that the development and metabolism of CO(2)-incubated embryos differ from control incubated embryos. [less ▲]

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See detailInteraction between beta-lactam antibiotics and exocellular DD-carboxypeptidase-transpeptidase of Streptomyces R61
Frère, Jean-Marie ULg; Leyh-Bouille, Mélina; Ghuysen, Jean-Marie ULg et al

in European Journal of Biochemistry (1974), 50(1), 203-214

On the basis of steady-state kinetics, inhibition of the exocellular dd-carboxypeptidase-trans-peptidase of Streptomyces R61 by β-lactam antibiotics was competitive with regard to the donor substrate ... [more ▼]

On the basis of steady-state kinetics, inhibition of the exocellular dd-carboxypeptidase-trans-peptidase of Streptomyces R61 by β-lactam antibiotics was competitive with regard to the donor substrate. However, the complexes formed between the Streptomyces R61 enzyme and various β-lactam antibiotics were relatively stable, exhibiting half-lives of 40 to 80 min at 37°C and neutral pH. During breakdown of the complexes the protein underwent reactivation, whereas the released antibiotic molecule was chemically altered. With [14C]benzylpenicillin, the released compound was neither benzylpenicillin nor benzylpenicilloic acid. The properties of the Streptomyces R61 enzyme β-lactam antibiotic complexes were compared with those of the complexes formed between the same antibiotics and either the membrane-bound transpeptidase from Streptomyces R61 or the exocellular dd-carboxypeptidase-transpeptidase of Streptomyces R39. [less ▲]

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See detailThe interaction between Bovine Leukemia Virus and its target cell.
Burny, Arsène; Kettmann, Richard ULg; Willems, Luc ULg et al

in AIDS Research and Human Retroviruses (1992), 8

Previous results indicate that the external glycoprotein gp51 of bovine leukemia virus plays an important role in the process of cell fusion induced by bovine leukemia virus (Bruck, C., Mathot, S ... [more ▼]

Previous results indicate that the external glycoprotein gp51 of bovine leukemia virus plays an important role in the process of cell fusion induced by bovine leukemia virus (Bruck, C., Mathot, S., Portetelle, D., Berte, C., Franssen, J. D., Herion, P., and Burny, A. (1982) Virology 122, 342-352; Voneche, V., Portetelle., D., Kettmann, R., Willems, L., Limbach, K., Paoletti, E., Ruysschaert, J. M., Burny, A., and Brasseur, R. (1992) Proc. Natl. Acad. Sci. U. S. A. 89, 3810-3814) and suggest that a region encompassing residues 23 and 25 of gp51 is involved in this process (Portetelle, D., Couez, D., Bruck, C., Kettmann, R., Mammerickx, M., Van der Maaten, M., Brasseur, R., and Burny, A. (1989) Virology 169, 27-33; Mamoun, R., Morisson, M., Rebeyrotte, N., Busetta, B., Couez, D., Kettmann, R., Hospital, M., and Guillemain, B. (1990) J. Virol. 64, 4180-4188). X-ray diffraction studies performed on envelope glycoproteins of influenza virus indicate that the NH2-terminal part of the external glycoprotein lies very close to the fusion peptide. The same overall structure seems to exist in human immunodeficiency virus as suggested by site-directed mutagenesis followed by syncytia induction assays. Our theoretical studies indicate that a segment expanding between residues 19 and 27 of gp51 probably adopts an amphipathic beta-strand structure. We hypothesize that the amphipathic 19-27 structure of gp51 plays an important role in the process of membrane fusion by interacting with the fusion peptide or with another region of gp30. Mutational analysis disrupting the amphipathy of the 19-27 region strongly altered the fusogenic capacity of the gp51-gp30 complex. [less ▲]

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See detailInteraction between dendritic cells and nerve fibres in lymphoid organs after oral scrapie exposure
Dorban, Gauthier ULg; Defaweux, Valérie ULg; Demonceau, Christine ULg et al

in Virchows Archiv (2007), 451(6), 1057-1065

In transmissible spongiform encephalopathies (TSEs), the infectious agent, called PrPsc, an abnormal isoform of the cellular prion protein, accumulates and replicates in lymphoid organs before affecting ... [more ▼]

In transmissible spongiform encephalopathies (TSEs), the infectious agent, called PrPsc, an abnormal isoform of the cellular prion protein, accumulates and replicates in lymphoid organs before affecting the nervous system. To clarify the cellular requirements for the neuro-invasion of the scrapie agent from the lymphoid organs to the central nervous system, we have studied, by confocal microscopy, the innervations within Peyer's patches, mesenteric lymph nodes and the spleen of mice in physiological conditions and after oral exposure to prion. Contacts between nerve fibres and PrPsc-associated cells, dendritic cells (DCs) and follicular dendritic cells (FDCs), were evaluated in preclinical prion-infected mice. Using a double immunolabelling strategy, we demonstrated the lack of innervation of PrPsc-accumulating cells (FDCs). Contacts between nerve fibers and PrPsc-propagating cells (DCs) were detected in T-cell zones and cell-trafficking areas. This supports, for the first time, the possible implication of dendritic cells in the prion neuroinvasion process. [less ▲]

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See detailInteraction between dietary protein level and source of fermentable carbohydrates in the gastrointestinal tract of pigs
Pieper, Robert; Boudry, Christelle ULg; Vahjen, Wilfried et al

in International workshop on nutrition and intestinal microbiota host interaction in the pig : Book of abstracts (2013, October 24)

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See detailInteraction between earthworms and soil fungi: volatiles attraction
Zirbes, Lara ULg; Thonart, Philippe ULg; Wathelet, Jean-Paul ULg et al

in 9th International Symposium on Earthworm Ecology (2010)

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See detailInteraction between eustacy and block-faulting in the Carboniferous of the Visé-Maastricht area (Belgium, the Netherlands)
Poty, Edouard ULg; Delculee, Sandrine ULg

in Zeitschrift der Deutschen Gesellschaft für Geowissenschaften [=ZDGG] (2011), 162(2), 117-126

The Visé–Maastricht sedimentation area (VSA) is situated at the eastern end of the Brabant Massif and suffered block-faulting tectonics during Lower Carboniferous time. The south edge of the VSA, the area ... [more ▼]

The Visé–Maastricht sedimentation area (VSA) is situated at the eastern end of the Brabant Massif and suffered block-faulting tectonics during Lower Carboniferous time. The south edge of the VSA, the area corresponding now to the vicinity of Visé, comprised three main tectonic blocks: the Hermalle-sous-Argenteau, Souvré and Bombaye blocks. They were bounded to south by the Booze–Val-Dieu block. To the north, in the vicinity of Maastricht, blocks are not well differ- entiated and are referred to as the Maastricht block system. From the end of the Tournaisian, the latter evolved into a rap- idly subsiding graben, recording mainly debris fl ows and limestone turbidites, whereas the southern blocks remained rela- tively high. Through much of Lower Carboniferous time, they were emergent, but during high eustatic sea levels, they were fl ooded and covered by limestone deposits. The differences in the nature and the age of the deposits between blocks result from the interaction between block-faulting and eustacy. In the VSA, the Upper Devonian and Lower Tournaisian (Hastarian) deposits are similar to those known in the north part of the Namur-Dinant Basin. But from the late Tournaisian (Ivorian), the uplift of the Booze–Val-Dieu block prevented all connections with the Namur-Dinant Basin and the VSA became linked with the Campine Basin. The Souvré block subsided from the latest Givetian to the late Frasnian and recorded a thick middle Frasnian limestone series, but was later emergent, so much that karstic cavities developed. The Souvré block was submerged for a short time at the top of the Tournaisian, during the very high highstand (HST) corresponding to eustatic sequence 4, and the caves fi lled up with sediments. The Hermalle-sous-Argenteau and the Bombaye blocks, situated respectively west and east of the Souvré block, evolved in the same way during the late Devonian. They subsided slightly from the earliest Tournaisian to the late Viséan (Warnan- tian), but usually remained emergent and recorded deposits only during times of high eustatic levels corresponding to the early Tournaisian (for the Bombaye block), the end of the Tournaisian (HST of sequence 4), the end of the early Viséan (HST of sequence 6), then the late Viséan (HST of sequences 9 and 10). In its southern part, the Hermalle-sous-Argenteau block recorded also lowermost Viséan limestones correlated with the highstand of the eustatic sequence 5, probably as a result of the tilting of the block to the south at this time. [less ▲]

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See detailInteraction between hippocampal and striatal systems predicts subsequent consolidation of motor sequence memory.
Albouy, Geneviève; Sterpenich, Virginie; Vandewalle, Gilles ULg et al

in PLoS ONE (2013), 8(3), 59490

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See detailInteraction between human papillomavirus (HPV) and natural killer (NK) cells
Renoux, Virginie ULg; Longton, Laurence; Dortu, Estelle ULg et al

Conference (2007, October 10)

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See detailInteraction between modal domains: The case of the Subjunctive in Late Egyptian
Polis, Stéphane ULg

Conference (2010, March 09)

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See detailInteraction between monobactams and model D-alanyl-D-alanine-cleaving peptidases
Frère, Jean-Marie ULg; Klein, Daniel; Kelly, Judith A et al

in FEMS Microbiology Letters (1984), 21

Several monobactams reacted with the serine dd-peptidases of Streptomyces R61 and Actinomadura R39 in a manner similar to that of bicyclic penicillins and cephalosporins. The dissociation constants of the ... [more ▼]

Several monobactams reacted with the serine dd-peptidases of Streptomyces R61 and Actinomadura R39 in a manner similar to that of bicyclic penicillins and cephalosporins. The dissociation constants of the Michaelis complexes formed between the R61 enzyme and sulfazecin (32 μM) and between the R39 peptidase and SQ 26324 (0.35 μM) had the lowest values ever observed with any β-lactam compound, suggesting an excellent fit of these two monobactams with the active sites of the respective enzymes. Azthreonam had a very poor inactivating potency, confirming its high selective reactivity towards the penicillin binding protein No. 3 of Escherichia coli. The Zn2+dd-peptidase (from Streptomyces albus G) had a high intrinsic resistance to β-lactam compounds whether they possessed a mono- or a bicyclic structure. [less ▲]

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