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See detailOrigin of radial glial cells in cerebral mouse cortex: A study using combined immunohistochemical and 3H thymidine labeling
Misson, Jean-Paul ULg; Edwards, M. A.; Yamamoto, M. et al

in Neuroscience Research. Supplement : The Official Journal of the Japan Neuroscience Society (1986)

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See detailOrigin of reversed vortex ratchet motion
Gillijns, W.; Silhanek, Alejandro ULg; Moshchalkov, V. V. et al

in Physical Review Letters (2007), 99(24),

We experimentally demonstrate that the origin of multiply reversed rectified vortex motion in an asymmetric pinning landscape not only is a consequence of the vortex-vortex interactions but also ... [more ▼]

We experimentally demonstrate that the origin of multiply reversed rectified vortex motion in an asymmetric pinning landscape not only is a consequence of the vortex-vortex interactions but also essentially depends on the ratio between the characteristic interaction distance and the period of the asymmetric pinning potential. We study four samples with different periods d of the asymmetric potential. For large d the dc voltage V(dc) recorded under a ac excitation indicates that the average vortex drift is from bigger to smaller dots for all explored positive fields. As d is reduced, a series of sign reversals in the dc response are observed as a function of field. We show that the number of sign reversals increases as d decreases. These findings are in agreement with recent computer simulations and illustrate the relevance of the different characteristic lengths for the vortex rectification effects. [less ▲]

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See detailOrigin of Saturn's aurora: Simultaneous observations by Cassini and the Hubble Space Telescope
Bunce, E. J.; Arridge, C. S.; Clarke, J. T. et al

in Journal of Geophysical Research (2008), 113(A9),

Outer planet auroras have been imaged for more than a decade, yet understanding their physical origin requires simultaneous remote and in situ observations. The first such measurements at Saturn were ... [more ▼]

Outer planet auroras have been imaged for more than a decade, yet understanding their physical origin requires simultaneous remote and in situ observations. The first such measurements at Saturn were obtained in January 2007, when the Hubble Space Telescope imaged the ultraviolet aurora, while the Cassini spacecraft crossed field lines connected to the auroral oval in the high-latitude magnetosphere near noon. The Cassini data indicate that the noon aurora lies in the boundary between open- and closed-field lines, where a layer of upward-directed field-aligned current flows whose density requires downward acceleration of magnetospheric electrons sufficient to produce the aurora. These observations indicate that the quasi-continuous main oval is produced by the magnetosphere-solar wind interaction through the shear in rotational flow across the open-closed-field line boundary. [less ▲]

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See detailThe origin of the alpha-domain intermediate in the folding of hen lysozyme
Matagne, André ULg; Chung, E. W.; Ball, L. J. et al

in Journal of Molecular Biology (1998), 277(5), 997-1005

Stopped-flow fluorescence and circular dichroism spectroscopy have been used in conjunction with quenched-flow hydrogen exchange labelling, monitored by electrospray ionization mass spectrometry, to ... [more ▼]

Stopped-flow fluorescence and circular dichroism spectroscopy have been used in conjunction with quenched-flow hydrogen exchange labelling, monitored by electrospray ionization mass spectrometry, to compare the refolding kinetics of hen egg-white lysozyme at 20 degrees C and 50 degrees C. At 50 degrees C there is clear evidence for distinct fast and slow refolding populations, as observed at 20 degrees C, although folding occurs significantly more rapidly. The folding process is, however, substantially more cooperative at the higher temperature. In particular, the transient intermediate on the major refolding pathway at 20 degrees C, having persistent native-like structure in the alpha-helical domain of the protein, is not detected by hydrogen exchange labelling at 50 degrees C. Ln addition, the characteristic maximum in negative ellipticity and the minimum in fluorescence intensity observed in far UV CD and intrinsic fluorescence experiments at 20 degrees C, respectively, are not seen at 50 degrees C. Addition of 2 M NaCl to the refolding buffer at 50 degrees C, however, regenerates both the hydrogen exchange and optical properties associated with the alpha-domain intermediate but has no significant effect on the overall refolding kinetics. Together with previous findings, these results indicate that non-native interactions within the alpha-domain intermediate are directly responsible for the unusual optical properties observed during refolding, and that this intermediate accumulates as a consequence of its intrinsic stability in a folding process where the formation of stable structure in the beta-domain constitutes the rate-limiting step for the majority of molecules. (C) 1998 Academic Press Limited. [less ▲]

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See detailThe origin of the forests in the North of the Congo Republic: an anthraco-pedological contribution.
Gillet, Jean-François; Beeckman, H.; Doucet, Jean-Louis ULg

in Damblon, F.; Court-Picon, M. (Eds.) Geological survey of Belgium professional papers N. 303-2008/1 (2008)

The vegetation of the Sangha region in the North of the Congo Republic is composed of a mosaic of forest formations including semi-deciduous humid dense forests characterized by Ulmaceae and Sterculiaceae ... [more ▼]

The vegetation of the Sangha region in the North of the Congo Republic is composed of a mosaic of forest formations including semi-deciduous humid dense forests characterized by Ulmaceae and Sterculiaceae, evergreen forests with Gilbertiodendron dewevrei and woodland with Marantaceae. Palynological analyses proved that this region witnessed an arid phase 2500 years ago. This was associated with an important reduction of the forest cover and an equal extension of savannahs that could have facilitated the migrations of the Bantou people and the propagation of the shifting cultivation agriculture in the whole region which is, still at the moment, sparsely populated. In order to verify climatic and anthropological influences on the present composition of the forest vegetation, a pedological investigation has been set up in the region of Pokola (1.5° N; 16.5 °E) comprising 43 drillings and 12 pits along a gradient covering the different forest types. Charcoal has been found in 84% of the cores in all the forest formations especially between 30 cm and 60 cm depth. Charred oil palm seeds (Elaeis guineensis), often a culture accompanying species, have been found in 60% of the pits. C14 analysis revealed dates between 600 and 2200 years BP. Pedological analyses showed the association between semi-deciduous humid dense forest and red ferralsols, between Marantaceae woodlands and ochre ferralsols (poorer than the former) and between Gilbertiodendron dewevrei stands and pseudogleys and gleysols. The identification of the botanical taxon of charcoal fragments from tropical regions deals with important limitations due to scarce reference collections that are far from being complete. Therefore it is crucial to combine a thorough knowledge of the different vegetation types and their character species with a wood anatomical study. Given the hypothesised strong influence of man induced perturbations and past climatic changes, these results emphasize the importance of edaphic factors in differentiating the forest stands in the North of the Congo Republic. They also permit a better understanding of a potential evolution of the forests in this region driven by the actual climatic changes. [less ▲]

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See detailThe origin of two-dimensional electron gases at oxide interfaces: insights from theory
Bristowe, Nicholas ULg; Ghosez, Philippe ULg; Littlewood, P.B. et al

in Journal of Physics : Condensed Matter (2014), 26

The response of oxide thin films to polar discontinuities at interfaces and surfaces has generated enormous activity due to the variety of interesting effects that it gives rise to. A case in point is the ... [more ▼]

The response of oxide thin films to polar discontinuities at interfaces and surfaces has generated enormous activity due to the variety of interesting effects that it gives rise to. A case in point is the discovery of the electron gas at the interface between LaAlO3 and SrTiO3, which has since been shown to be quasi-two-dimensional, switchable, magnetic and/or superconducting. Despite these findings, the origin of the two-dimensional electron gas is highly debated and several possible mechanisms remain. Here we review the main proposed mechanisms and attempt to model expected effects in a quantitative way with the ambition of better constraining what effects can/cannot explain the observed phenomenology. We do it in the framework of a phenomenological model constructed to provide an understanding of the electronic and/or redox screening of the chemical charge in oxide heterostructures. We also discuss the effect of intermixing, both conserving and not conserving the total stoichiometry. [less ▲]

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See detailThe origin of unidentified interstellar absorption lines
Swings, Polydore ULg; Öhman, Y.

in Observatory (The) (1939), 62

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See detailOrigin, biodiversity, and extinction of Cretaceous ichthyosaurs
Fischer, Valentin ULg

Doctoral thesis (2013)

Ichthyosauria is a group of reptiles that colonized numerous niches in Mesozoic marine ecosystems. Their Cretaceous representatives were however regarded as undiversified, especially compared to their ... [more ▼]

Ichthyosauria is a group of reptiles that colonized numerous niches in Mesozoic marine ecosystems. Their Cretaceous representatives were however regarded as undiversified, especially compared to their Triassic and Jurassic ancestors, because only a few species are regarded as valid in the Cretaceous. Besides, most of them belong to a single genus, Platypterygius, whose taxonomy and phylogeny are problematic. Therefore, Cretaceous ichthyosaurs have been widely considered as the last members of a group on the decline, although the timing, the cause and the magnitude of their extinction phases greatly vary among authors. Yet, a great part of the Cretaceous ichthyosaur record, the Eurasian material, has been neglected from more than 100 years; theories explaining the evolution of the last ichthyosaurs therefore miss the biggest part of the picture. Notably, how ichthyosaurs diversified and went extinct during the Cretaceous is basically unknown. To tackle these topics, I assess the taxonomy of Cretaceous ichthyosaurs from Eurasia, test their phylogenetic position within a global analysis of post-Triassic ichthyosaurs, evaluate their ecological diversity and analyse their phases of radiation and extinction. Assessment of the Eurasian material led to the discovery of seven new taxa (“Iraq animal”, Acamptonectes densus, “Lenin Form”, Sveltonectes insolitus, Sveltonectes “Ebbo Form”, “Sisteron Form”, “Colossal Form”) and the re-installation of several other taxa as valid (Simbirskiasaurus birjukovi, P. bannovkensis, Cetarthrosaurus walkeri, P. hercynicus). Morphological and phylogenetic evidence suggest Platypterygius hides a very large generic diversity and should be limited to its type species P. platydactylus; however, the interrelationships of the large platypterygiine ichthyosaurs from the Aptian–Cenomanian interval are poorly constrained. Phylogenetic analyses provide robust evidence for disparate origins of Cretaceous ichthyosaurs; these animals actually belonged to three distinct clades that diverged several tens of million years before the Cretaceous. These three clades had contrasted evolutionary histories and colonized disctinct ecological niches during the Cretaceous. Survival and extinction rates demonstrate ichthyosaurs suffered no extinction event at the Jurassic–Cretaceous boundary. They were therefore highly diverse during the Cretaceous, although the sampling of some stages remains inadequate. Notably, up to eight genera were present during the late Albian, a few million years before their final extinction. This extinction appears staggered over four phases that span the entire Cenomanian stage; it also forms one of the facets of a much wider event that affected most levels of marine trophic chains during the Cenomanian. Compilation of published data and collaborations with other specialists show that the radiation of snakes, mosasaurs, and numerous lineages of modern fishes, the severe extinctions among cephalopods and rudist bivalves and the complete extinction of ichthyosaurs likely belong to the same global turnover event. The magnitude, diversity and simultaneity of the biotic responses strongly suggest that global physico-chemical factors triggered this profound reorganization of the marine ecosystems, notably the conjunction of a rather brutal onset of extremely high temperatures and sea level, intense marine volcanism and phases of worldwide ocean anoxia. [less ▲]

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See detailORIGIN: metal creation and evolution from the cosmic dawn
den Herder, Jan-Willem; Piro, Luigi; Ohashi, Takaya et al

in Experimental Astronomy (2012), 34

ORIGIN is a proposal for the M3 mission call of ESA aimed at the study of metal creation from the epoch of cosmic dawn. Using high-spectral resolution in the soft X-ray band, ORIGIN will be able to ... [more ▼]

ORIGIN is a proposal for the M3 mission call of ESA aimed at the study of metal creation from the epoch of cosmic dawn. Using high-spectral resolution in the soft X-ray band, ORIGIN will be able to identify the physical conditions of all abundant elements between C and Ni to red-shifts of z = 10, and beyond. The mission will answer questions such as: When were the first metals created? How does the cosmic metal content evolve? Where do most of the metals reside in the Universe? What is the role of metals in structure formation and evolution? To reach out to the early Universe ORIGIN will use Gamma-Ray Bursts (GRBs) to study their local environments in their host galaxies. This requires the capability to slew the satellite in less than a minute to the GRB location. By studying the chemical composition and properties of clusters of galaxies we can extend the range of exploration to lower redshifts ( z ˜0.2). For this task we need a high-resolution spectral imaging instrument with a large field of view. Using the same instrument, we can also study the so far only partially detected baryons in the Warm-Hot Intergalactic Medium (WHIM). The less dense part of the WHIM will be studied using absorption lines at low redshift in the spectra for GRBs. The ORIGIN mission includes a Transient Event Detector (coded mask with a sensitivity of 0.4 photon/cm[SUP]2[/SUP]/s in 10 s in the 5-150 keV band) to identify and localize 2000 GRBs over a five year mission, of which ˜65 GRBs have a redshift >7. The Cryogenic Imaging Spectrometer, with a spectral resolution of 2.5 eV, a field of view of 30 arcmin and large effective area below 1 keV has the sensitivity to study clusters up to a significant fraction of the virial radius and to map the denser parts of the WHIM (factor 30 higher than achievable with current instruments). The payload is complemented by a Burst InfraRed Telescope to enable onboard red-shift determination of GRBs (hence securing proper follow up of high-z bursts) and also probes the mildly ionized state of the gas. Fast repointing is achieved by a dedicated Controlled Momentum Gyro and a low background is achieved by the selected low Earth orbit. [less ▲]

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See detailOriginal 2-alkylamino-6-halogenoquinazolin-4(3H)-ones and KATP channel activity
Somers, F.; Ouedraogo, R.; Antoine, M.-H. et al

in Journal of Medicinal Chemistry (2001), 44

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See detailAn original adaptation of photosynthesis in the marine green alga Ostreococcus.
Cardol, Pierre ULg; Bailleul, Benjamin; Rappaport, Fabrice et al

in Proceedings of the National Academy of Sciences of the United States of America (2008), 105(22), 7881-6

Adaptation of photosynthesis in marine environment has been examined in two strains of the green, picoeukaryote Ostreococcus: OTH95, a surface/high-light strain, and RCC809, a deep-sea/low-light strain ... [more ▼]

Adaptation of photosynthesis in marine environment has been examined in two strains of the green, picoeukaryote Ostreococcus: OTH95, a surface/high-light strain, and RCC809, a deep-sea/low-light strain. Differences between the two strains include changes in the light-harvesting capacity, which is lower in OTH95, and in the photoprotection capacity, which is enhanced in OTH95. Furthermore, RCC809 has a reduced maximum rate of O(2) evolution, which is limited by its decreased photosystem I (PSI) level, a possible adaptation to Fe limitation in the open oceans. This decrease is, however, accompanied by a substantial rerouting of the electron flow to establish an H(2)O-to-H(2)O cycle, involving PSII and a potential plastid plastoquinol terminal oxidase. This pathway bypasses electron transfer through the cytochrome b(6)f complex and allows the pumping of "extra" protons into the thylakoid lumen. By promoting the generation of a large DeltapH, it facilitates ATP synthesis and nonphotochemical quenching when RCC809 cells are exposed to excess excitation energy. We propose that the diversion of electrons to oxygen downstream of PSII, but before PSI, reflects a common and compulsory strategy in marine phytoplankton to bypass the constraints imposed by light and/or nutrient limitation and allow successful colonization of the open-ocean marine environment. [less ▲]

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See detailOriginal cromakalim analogues as KATP channel openers
Florence, X.; De Tullio, Pascal ULg; Pirotte, Bernard ULg et al

Conference (2009, June)

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See detailOriginal cromakalim analogues as KATP channel openers
Florence, Xavier ULg; De Tullio, Pascal ULg; Pirotte, Bernard ULg et al

in Metabolic and Functional Research on Diabetes (2009), 2

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See detailOriginal findings associated with two cases of bovine papular stomatitis
Dal Pozzo, Fabiana ULg; Martinelle, Ludovic ULg; Gallina, L. et al

in Journal of Clinical Microbiology (2011), 49(12), 4397-4400

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See detailAn Original integration scheme. Application to a simple shear test of anisotropic material
de Montleau, P.; Habraken, Anne ULg

in International Journal for Numerical Methods in Engineering (2000)

Finite element simulations involving large deformations and large displacements imply the setting up of a precise kinematic for the integration scheme. Moreover, anisotropic mechanical behaviors have to ... [more ▼]

Finite element simulations involving large deformations and large displacements imply the setting up of a precise kinematic for the integration scheme. Moreover, anisotropic mechanical behaviors have to be expressed in an appropriate local reference frame. In the present paper, a computational procedure is derived from a particular velocity gradient de¯nition. The implementation in the ¯nite element code Lagamine developed in the M&S department is described. An application to a simple shear test is proposed. A sinusoidal behavior of the shear component stress is emphasized. It is due to the anisotropic yield locus and appears in the case of a saturated isotropic hardening law. [less ▲]

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See detailOriginal lithotomy positioning for transperineal extracorporeal shockwave lithotripsy for distal ureteric calculi with Tripter X1.
Andrianne, Robert ULg; Vandeberg, Colette ULg; Bonnet, Pierre ULg et al

in European Urology (1992), 22(2), 134-6

Extracorporeal shockwave lithotripsy (ESWL) has been initially designed for stones located in the kidney and the upper ureter. Our lithotripter is no exception. Its components (the table and the ... [more ▼]

Extracorporeal shockwave lithotripsy (ESWL) has been initially designed for stones located in the kidney and the upper ureter. Our lithotripter is no exception. Its components (the table and the orientation of the semi-ellipsoid reflector) are adapted for the treatment of kidney or lumbar ureter stones. However, the elements forming the unit of treatment (the table, the C-arm and the Tripter) can be modified in such a way that focalization of stones of the lower ureter becomes possible through a perineal exposure. The aim is to avoid the pelvic bone shield while a good focalization of the stone is realized. From June 1989 to March 1991, 35 patients were treated for distal ureteric stones by ESWL in this original positioning. [less ▲]

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See detailAn original methodology to study the synovial tissue in OA patient
Lambert, Cécile ULg; Dubuc, Jean-Emile; Henrotin, Yves ULg

Poster (2012, April 19)

Purpose: Synovial membrane plays a key role in osteoarthritis (OA) pathophysiology, contributing to both patient symptoms and disease progression. Using an original methodology comparing normal/reactive ... [more ▼]

Purpose: Synovial membrane plays a key role in osteoarthritis (OA) pathophysiology, contributing to both patient symptoms and disease progression. Using an original methodology comparing normal/reactive (N/R) and inflammatory (I) synovial membrane areas from the same OA patient, we investigated the crosstalk between inflammation and angiogenesis. We also analyzed the gene expression pattern of synovial cells from these different areas and identified differentially regulated pathways. Methods: Synovial cells (SC) were isolated from OA synovial specimens obtained from patients undergoing knee replacement. The inflammatory status of the synovial membrane was characterized by the surgeon according the macroscopic criteria including the synovial vascularization, the villi formation and the hypertrophic aspect of the tissue. At the surgery time, the synovial membrane was dissected and the biopsies from N/R and I areas cultured separately for a period of 7 days. Inflammatory and angiogenic mediators were evaluated in the culture supernatant by immunoassays (ELISA) or visualized by immunohistochemistry. Gene expression profiling between N/R and I areas was performed using Illumina’s multi-sample format human HT-12 BeadChip (Illumina Inc.). Results: Immunohistochemistry showed an increase of lymphocyte infiltration, vascular density and VEGF expression in I compared N/R synovial biopsies. Synovial cells from I areas produced more IL-6, IL-8 and VEGF but less TSP-1 than cells isolated from N/R synovial biopsies. By microarray analysis, 896 differentially expressed genes between N/R and I zones were identified. Among them, 576 genes were upregulated (I/NR > 1.5) and 320 downregulated (I/NR  0.75). A significant number of the top ranking differentially expressed genes were identified as inflammatory, cartilage metabolism, Wnt or angiogenic pathways. Conclusion: In this study, we have demonstrated the pro-inflammatory and pro-angiogeneic status of I area of the OA synovial membrane. Using a unique culture system, this study is the first to identify different expression pattern between two areas of the synovial membrane in the same OA patient. This original methodology could be further used to go deeper into the knowledge of the role of synovial membrane in OA. Possibilities for valorization: This analysis provided interesting information regarding new potent intermediates that could be potential new targets for the diagnosis or treatment of OA. [less ▲]

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