Publications ORBi OA
Bookmark and Share    
Full Text
See detailCes tendinopathies qui nous submergent
Kaux, Jean-François ULg

Conference (2012, May 05)

Des traitements conservateurs classiques ( AINS, infiltrations, rééducation excentrique) aux nouveaux traitements ( ondes de choc, concentrés plaquettaires, …) . Chirurgie. Particularités de l’épaule.

Detailed reference viewed: 100 (11 ULg)
Full Text
See detailEvidence for a partial epithelial-mesenchymal transition in postnatal stages of rat auditory organ morphogenesis
Johnen, Nicolas ULg; Cloes, Marie ULg; Thelen, Nicolas ULg et al

Poster (2012, May 04)

An epithelial-mesenchymal transition is a biological process that allows a polarized epithelial cell to undergo multiple biochemical changes that enable it to assume a mesenchymal cell phenotype. During ... [more ▼]

An epithelial-mesenchymal transition is a biological process that allows a polarized epithelial cell to undergo multiple biochemical changes that enable it to assume a mesenchymal cell phenotype. During this process, epithelial cells loosen cell-cell adhesion, module their polarity and rearrange their cytoskeleton: intermediate filaments typically switch from cytokeratin to vimentin. They also enhance their motility capacity. The epithelial-mesenchymal transition plays key roles in the formation of the body plan and in the differentiation of multiple tissues and organs but it is also involved in tissue repair, tissue homeostasis, fibrosis, and carcinoma progression. Until now, epithelial-mesenchymal transition has been rarely mentioned in the inner ear organogenesis. In chick, epithelial-mesenchymal transition has been reported as a possible mechanism of semicircular canal morphogenesis. More recently, an in vitro study has also indicated that sensory epithelial cells from mouse utricle can undergo an epithelial-mesenchymal transition to become cells expressing features of prosensory cells. By contrast, epithelial-mesenchymal transition has never been observed during auditory organ morphogenesis. The auditory organ, the organ of Corti, is a highly specialized structure composed by specific cellular types. The sensory cells are characterized by stereocilia at their apex and are necessary for the sound perception. Theses cells are supported by supporting cells. Based on their morphology and physiology, at least four types of supporting cells can be identified in the organ of Corti: inner and outer pillar cells, phalangeal cell and Deiter’s cells. The inner pillar cells and outer pillar cells combine to form the tunnel of Corti, a fluid filled triangular space that separates the single row of inner hair cells from the first row of outer hair cells. The Nuel spaces are another interval in the organ of Corti that is situated between the outer pillar cells and the different rows of outer hair cells and Deiters cells. To determine whether an epithelial-mesenchymal transition may play a role in the morphogenesis of the auditory organ, we studied the spatial localization of several epithelial-mesenchymal transition markers, the cell-cell adhesion molecules and intermediate filament cytoskeletal proteins, in epithelium of the dorsal cochlea during development of the rat organ of Corti from 18th embryonic day until 25th postnatal day. We examined by confocal microscopy immunolabelings on cryosections of whole cochleae with antibodies anti-cytokeratins as well as with antibodies anti-vimentin, anti-E-cadherin and anti-beta-catenin.Our results showed a partial loss of E-cadherin and beta-catenin between supporting cells at P8 and P12, respectively, and a temporary appearance of vimentin in pillar cells and Deiters between P8 and P10. Our results show a local loss of adhesion between supporting cells of the OC from P8, an increase expression of cytokeratins in supporting cells around P10 and a temporary appearance of vimentin in supporting cells at P8-10. These observations suggest that a partial epithelial-mesenchymal transition might be involved in the remodeling of the Corti organ during the postnatal stages of development in rat. [less ▲]

Detailed reference viewed: 36 (16 ULg)
Full Text
Peer Reviewed
See detailInfluence of artificial pinning on vortex lattice instability in superconducting films
Silhanek, Alejandro ULg; Leo, A.; Grimaldi, G. et al

in New Journal of Physics (2012), 14

In superconducting films under an applied dc current, we analyze experimentally and theoretically the influence of engineered pinning on the vortex velocity at which the flux-flow dissipation undergoes an ... [more ▼]

In superconducting films under an applied dc current, we analyze experimentally and theoretically the influence of engineered pinning on the vortex velocity at which the flux-flow dissipation undergoes an abrupt transition from low to high resistance. We argue, based on a nonuniform distribution of vortex velocity in the sample, that in strongly disordered systems the mean critical vortex velocity for flux-flow instability (i) has a nonmonotonic dependence on magnetic field and (ii) decreases as the pinning strength is increased. These findings challenge the generally accepted microscopic model of Larkin and Ovchinnikov (1979 J. Low. Temp. Phys. 34 409) and all subsequent refinements of this model which ignore the presence of pinning centers. [less ▲]

Detailed reference viewed: 25 (4 ULg)
Full Text
See detailLithostratigraphie, sédimentologie et analyse séquentielle du Quartzite de Berlé (Emsien supérieur, Grand-Duché de Luxembourg)
Michel, Jonathan ULg

Doctoral thesis (2012)

The Lower Devonian is a period of interest because it is characterized by the first transgression of the Rheic Ocean, after the Caledonian orogeny, over the coasts of the Old Red Sandstones Continent. In ... [more ▼]

The Lower Devonian is a period of interest because it is characterized by the first transgression of the Rheic Ocean, after the Caledonian orogeny, over the coasts of the Old Red Sandstones Continent. In the Ardenne Basin, during this transgression, widespread siliciclastic deposits were deposited. From the Lochkovian to the Upper Emsian, the basin underwent various stages of development. The main object of this PhD thesis was to focus on one of these episodes recorded in the Neufchâteau-Wiltz-Eifel Basin. This work is the result of the integration of different techniques, such as field work, microscopic analyses, biostratigraphy, sequence stratigraphy, magnetic susceptibility and diagenesis. The analysis of the microfossil content of four sections in Luxembourg led to the identification of 23 species of spores and 11 species of acritarchs. Biostratigraphically, these spores confirmed the Emsian age of the different lithological units (“Couches de Clervaux”, “Quartzite de Berlé” and “Schistes de Wiltz”). The sedimentological analysis of the Neufchâteau-Wiltz-Eifel Basin is based on the study of more than 600 thin sections from 11 sections covering the entire basin. This study allowed to identify an estuary setting divided into three types of environments: an alluvial, a tidal and finally a marine distal environment. Detailed sedimentology associated with sequence stratigraphy of the whole Neufchâteau-Wiltz-Eifel Basin allowed to propose a vertical and lateral succession model of this estuarine setting. In this model, the “Quartzite de Berlé” corresponds to tidal sand ridges and changes laterally to the flaser bedded sandstones of the top of the “Couches de Clervaux”. This lateral facies transition tends to proof that the “Quartzite de Berlé” is a lenticular deposit. The “Quartzite de Berlé” is a prominent feature in the landscapes and a very resistant rock appreciated as a building material. Diagenesis study allows a better understanding of the mechanisms responsible for these characteristics, trough the identification of different cements and authigenic minerals. Temporal relationships between these different components are integrated in a paragenetic modelisation that includes four distinct phases: an eogenetic, a mesogenetic, a metamorphic and a telogenetic phase. The clay mineralogy (illite cristallinity) shows that the “Quartzite de Berlé” underwent variable conditions of burial, depending of the area considered. Our results point out that this variability is related to the pre-orogenetic rifting stage of the Rhenohercynian Basin. Finally, the use of magnetic susceptibility, suggested that in proximal setting, the magnetic susceptibility signal is mainly controlled by environmental parameters (water agitation, sedimentation rates) and diagenesis. [less ▲]

Detailed reference viewed: 124 (18 ULg)
Full Text
See detailValidation of Adult Bone Marrow Stromal Cells in Cellular Therapy Protocols, using a Mouse Model for Parkinson’s Disease
Neirinckx, Virginie ULg; Laudet, Emerence; Rogister, Bernard ULg et al

Poster (2012, May 04)

Parkinson’s disease (PD) is the second most common neurodegenerative disorder in industrialized countries. Its main characteristic relies in a progressive loss of dopaminergic (DA) neurons in the ... [more ▼]

Parkinson’s disease (PD) is the second most common neurodegenerative disorder in industrialized countries. Its main characteristic relies in a progressive loss of dopaminergic (DA) neurons in the Substantia Nigra pars compacta (SNpc), resulting in a deficient dopamine release in the striatum and then promoting important defects in motility regulation. Unfortunately, motor symptoms are generally diagnosed once 80% of nigrostriatal neurons are already lost. The emergence of neuroprotective/-restorative strategies is then increasingly raising hope, and a lot of people now focus on cell therapy experiments. Adult bone marrow stromal stem cells (BMSCs) have already been demonstrated as ideal candidates for cell therapy in nervous lesions, regarding their high multipotency and the fact they can be easily harvested in the patient himself. After it has been demonstrated that some BMSCs arise from the embryonic neural crest (NC), we compared NC-BMSCs and mesenchymal (M)-BMSCs in vitro, in terms of differenciation abilities and more particularly in terms of neural fate. We then wanted to investigate and compare the potential usefulness of both populations in the context of a neurological pathology. We have validated a MPTP mouse model, mimicking the specific loss of nigral neurons, and started setting up a cell therapy experiment using stereotaxic brain injection of the two types of BMSCs. The survival rate of grafted cells was analyzed as well as their migration or differentiation, and their ability to restore neuronal loss was also observed. Our first results showed that once grafted inside the brain of MPTP mice, NC-BMSCs survive for about a week, staying tightly close to each other the injection track with no visible sign of migration. Afterwards, cells begin to disappear and we only observe a mean survival rate of 1% after 28 days. Looking at the nigrostriatal pathway integrity, neural crest-BMSCs don’t seem to induce any improvement: they don’t differenciate into neural cells, neither replace lost DA cells, and they do not induce any sprouting of surviving DA neurons. While the M-BMSCs graft experiment has to be completed, these first results showed that NC-BMSCs at the stem cell state are not able to restore the lesioned system, and maybe a pre-differenciation step would be required to trigger those cells into a neuronal fate before grafting them in a MPTP-mouse brain. [less ▲]

Detailed reference viewed: 16 (4 ULg)
Full Text
See detailUnravelling the roles of lysine acetylation by Elp3 during inner ear development
Mateo Sanchez, Susana ULg; Delacroix, Laurence ULg; Laguesse, Sophie ULg et al

Poster (2012, May 04)

The inner ear is composed of a vestibular part that controls balance, and the cochlea, which is dedicated to hearing. In both parts of the inner ear, sensory epithelia comprise supporting cells ... [more ▼]

The inner ear is composed of a vestibular part that controls balance, and the cochlea, which is dedicated to hearing. In both parts of the inner ear, sensory epithelia comprise supporting cells surrounding the sensory hair cells. These cells bear at their apical surface a staircase-structured hair bundle, consisting of multiple rows of actin-based stereocilia and a single tubulin-based kinocilium. This hair bundle allows the transduction from mechanical stimuli, initiated by sound or gravitational changes, to electrical signals that will then be transmitted by neurons from the spiral ganglion (innervating hair cells of the cochlea) or the vestibular ganglion. The inner ear organogenesis requires a tightly regulated transcriptional program that can be affected by post-transcriptional and post-translational modifications among which lysine acetylation. Given the importance of acetylation homeostasis in controlling developmental processes, we planned to investigate its role in inner ear formation and focused our attention on Elp3 acetyl-transferase, a member of the Elongator complex recently implicated in neurogenesis. First, we have analysed Elp3 expression by in situ hybridization on wild type mice at different developmental stages (from E11.5 until P6) and showed that it was expressed in the entire early otocyst at E11.5 and persisted later in the sensory epithelium of the cochlea (the organ of Corti), in the stria vascularis and in the vestibule. To study the functional consequences of protein acetylation by the Elongator complex in the inner ear, we studied conditional knock-out mice (Elp3 cKO) in which Elp3 is depleted from the otic vesicle at E8.5. These mice, at stage P15, showed obvious balance dysfunction that was confirmed by a complete battery of behavioural tests: stereotyped circling ambulation, head bobbing, retropulsion, and absence of reaching response in the tail-hanging test. Unfortunately, the Elp3 cKO mice die before the onset of hearing, thus precluding any evaluation of hearing disorders. Balance defects in mice depleted for Elp3 is not due to vestibular structural abnormalities, since paint-filling experiments showed a normal inner ear anatomy compared to wild type mice. Moreover, immunostainings in the vestibule and in the organ of Corti indicated that cell patterning was not impaired in the absence of Elp3 since specialised cells are present and correctly organised at embryonic day E18.5 and later on. However, we were able to detect some defaults in hair cell bundle integrity and orientation in the auditory portion of inner ear from Elp3 cKO mice. We were also able to demonstrate an increased level of apoptosis in the Elp3 cKO spiral ganglion at E14.5 leading to a reduced number of fibers innervating the cochlear hair cells at P0 and P15. In conclusion, we have confirmed the expression of Elp3 in the inner ear and pointed out a role for this acetyl-transferase in balance function. Our results clearly show the implication of Elp3 in ciliogenesis, hair cell innervation and neuronal survival and we plan to go deeper in the mechanisms involved through the identification of the proteins acetylated by Elp3. [less ▲]

Detailed reference viewed: 132 (10 ULg)
Full Text
Peer Reviewed
See detailAuditory Resting-State Network Connectivity in Tinnitus: a Functionnal MRI Study.
MAUDOUX, Audrey ULg; LEFEBVRE, Philippe ULg; CABAY, Jean-Evrard ULg et al

in PLoS ONE (2012)

The underlying functional neuroanatomy of tinnitus remains poorly understood. Few studies have focused on functional cerebral connectivity changes in tinnitus patients. The aim of this study was to test ... [more ▼]

The underlying functional neuroanatomy of tinnitus remains poorly understood. Few studies have focused on functional cerebral connectivity changes in tinnitus patients. The aim of this study was to test if functional MRI ‘‘resting-state’’ connectivity patterns in auditory network differ between tinnitus patients and normal controls. Thirteen chronic tinnitus subjects and fifteen age-matched healthy controls were studied on a 3 tesla MRI. Connectivity was investigated using independent component analysis and an automated component selection approach taking into account the spatial and temporal properties of each component. Connectivity in extra-auditory regions such as brainstem, basal ganglia/NAc, cerebellum, parahippocampal, right prefrontal, parietal, and sensorimotor areas was found to be increased in tinnitus subjects. The right primary auditory cortex, left prefrontal, left fusiform gyrus, and bilateral occipital regions showed a decreased connectivity in tinnitus. These results show that there is a modification of cortical and subcortical functional connectivity in tinnitus encompassing attentional, mnemonic, and emotional networks. Our data corroborate the hypothesized implication of non-auditory regions in tinnitus physiopathology and suggest that various regions of the brain seem involved in the persistent awareness of the phenomenon as well as in the development of the associated distress. leading to disabling chronic tinnitus. [less ▲]

Detailed reference viewed: 146 (11 ULg)
Full Text
Peer Reviewed
See detailComportement élastique des articulations flexibles à col elliptique
Debongnie, Jean-François ULg

Conference (2012, May 04)

We present here amodel for the prediction of the elastic behaviour of elliptic notch hinges, including bending and shear in both planes, stretching and torsion. In a first step, an exact solution is ... [more ▼]

We present here amodel for the prediction of the elastic behaviour of elliptic notch hinges, including bending and shear in both planes, stretching and torsion. In a first step, an exact solution is established in the frame of the beam theory, making use of Sommerfeld's change of variable, which is well known in the lubrication theory. The second step is the deduction of the asymptotic solution for very thin hinges. Finally, and yhis is the most original part of our presentation, a simple corrective factor is deduced numerically, which enables to pass from the asymptotic solution to the exact one with a fair approximation in the practical range of thicknesses. <the simplicity of the obtained model has no equivalent in the literature, which is specially useful at the design stage. [less ▲]

Detailed reference viewed: 27 (8 ULg)
Full Text
See detailY a-t-il managérialisation de l'intervention sociale ?
Vrancken, Didier ULg

Conference given outside the academic context (2012)

Que ce soit au sein des entreprises privées, publiques ou au sein des associations, la managérialisation devient aujourd'hui un phénomène qui traverse également l'intervention sociale et engendre nombre ... [more ▼]

Que ce soit au sein des entreprises privées, publiques ou au sein des associations, la managérialisation devient aujourd'hui un phénomène qui traverse également l'intervention sociale et engendre nombre de contradictions pour les "travailleurs du social". [less ▲]

Detailed reference viewed: 76 (7 ULg)
Full Text
See detailQuestionnaire sur les manuels et sur l'évaluation. Version destinée aux étudiants de master/de l'AESS en langues modernes à l'ULg
Simons, Germain ULg; Delbrassine, Daniel ULg; Pagnoul, Pierre ULg et al

Computer development (2012)

Ce questionnaire a été conçu pour alimenter une communication sur les manuels scolaires de langues étrangères et la problématique de l'équité et une autre questionnant l'équité des outils d'évaluation en ... [more ▼]

Ce questionnaire a été conçu pour alimenter une communication sur les manuels scolaires de langues étrangères et la problématique de l'équité et une autre questionnant l'équité des outils d'évaluation en langues modernes en Communauté française de Belgique. Ces deux communications ont été présentées au Colloque "Supports didactiques, pratiques d'enseignement et préoccupations sociologiques sur les inégalités d'apprentissage" organisé dans le cadre du XVIIe Congrès de l'Association Mondiale des Sciences de l'Education (Reims, 3 au 8 juin 2012). Ces données déclaratives ont été collectées auprès des ETUDIANTS de l'AESS/du Master à finalité didactique en langues et littératures modernes de l'ULg. Parallèlement à ces données, nous avons collecté l'avis d'ENSEIGNANTS expérimentés et d'ELEVES du secondaire. La confrontation de ces différentes sources d'information a permis de nourrir notre communication. [less ▲]

Detailed reference viewed: 59 (3 ULg)
Full Text
See detailSpectroscopic binary processing within Gaia DPAC
Damerdji, Yassine ULg; Morel, Thierry ULg; Gosset, Eric ULg

in Orbital Couples: Pas de Deux in the Solar System and the Milky Way (2012, May 01)

Not Available

Detailed reference viewed: 4 (0 ULg)
Full Text
Peer Reviewed
See detailOn the sensitivity of closure phases to faint companions in optical long baseline interferometry
Le Bouquin, Jean-Baptiste; Absil, Olivier ULg

in Astronomy and Astrophysics (2012), 541

We explore the sensitivity and completeness of long baseline interferometric observations for detecting unknown, faint companions around bright unresolved stars. We derive a linear expression for the ... [more ▼]

We explore the sensitivity and completeness of long baseline interferometric observations for detecting unknown, faint companions around bright unresolved stars. We derive a linear expression for the closure phase signature of a faint companion in the high contrast regime (<0.1), and provide a quantitative estimation of the detection efficiency for the currently offered four-telescope configurations at the Very Large Telescope Interferometer. The results are compared to the performances provided by linear and Y-shaped interferometric configurations in order to identify the ideal array. We find that all configurations have a similar efficiency in discovering companions wider than 10mas. Assuming a closure phase accuracy of 0.25deg, that is typical of state-of-the-art instruments, we predict a median dynamic range of up to six magnitudes when stacking observations obtained at five different hour angles. Surveying bright stars to search for faint companions can be considered as an ideal filler programme for modern interferometric facilities because that places few constraints on the choice of the interferometric configuration. [less ▲]

Detailed reference viewed: 8 (1 ULg)
Full Text
Peer Reviewed
See detailHST/STIS spectroscopy of the magnetic Of?p star HD 108: the low state at ultraviolet wavelengths
Marcolino, W. L. F.; Bouret, J.-C.; Walborn, N. R. et al

in Monthly Notices of the Royal Astronomical Society (2012), 422

We present the first ultraviolet spectrum of the peculiar, magnetic Of?p star HD 108 obtained in its spectroscopic low state. The new data, obtained with the Space Telescope Imaging Spectrograph (STIS) on ... [more ▼]

We present the first ultraviolet spectrum of the peculiar, magnetic Of?p star HD 108 obtained in its spectroscopic low state. The new data, obtained with the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope, reveal significant changes compared to IUE spectra obtained in the high state: N Vλ1240, Si IVλ1400 and C IVλ1550 present weaker P Cygni profiles (less absorption) in the new data, while N IVλ1718 absorption is deeper, without the clear wind signature evident in the high state. Such changes contrast with those found in other magnetic massive stars, where more absorption is observed in the resonance doublets when the sightline is close to the plane of the magnetic equator. The new data show also that the photospheric Fe IV forest, at ˜1600-1700 Å, has strengthened compared to previous observations. The ultraviolet variability is large compared to that found in typical, non-magnetic O stars, but moderate when compared to the high-/low-state changes reported in the optical spectrum of HD 108 over several decades. We use non-local thermodynamic equilibrium (non-LTE) expanding-atmosphere models to analyse the new STIS observations. Overall, the results are in accord with a scenario in which the optical variability is mainly produced by magnetically constrained gas, close to the photosphere. The relatively modest changes found in the main ultraviolet wind lines suggest that the stellar wind is not substantially variable on a global scale. Nonetheless, multidimensional radiative-transfer models may be needed to understand some of the phenomena observed. [less ▲]

Detailed reference viewed: 15 (0 ULg)
Full Text
See detailZero Drift in Mean Anomaly of the Satellite of 1996 FG3 and its Implication for the BYORP Theory
Scheirich, P.; Pravec, P.; Mottola, S. et al

in Asteroids, Comets, Meteors 2012, Proceedings of the conference (2012, May 01)

An analysis of photometric observations of binary Near-Earth asteroid (175706) 1996 FG3, taken from 1996 to 2012, gave a single solution for a quadratic drift of the mean anomaly of the satellite, 0.0 deg ... [more ▼]

An analysis of photometric observations of binary Near-Earth asteroid (175706) 1996 FG3, taken from 1996 to 2012, gave a single solution for a quadratic drift of the mean anomaly of the satellite, 0.0 deg/yr^2, consistent with recent BYORP theory. [less ▲]

Detailed reference viewed: 17 (0 ULg)
Full Text
See detailConstraining Outgassing Activity in the Main-Belt Comet 176P/LINEAR with Herschel
de Val-Borro, M.; Hartogh, P.; Biver, N. et al

in Asteroids, Comets, Meteors 2012, Proceedings of the conference (2012, May 01)

176P/LINEAR was observed with the Heterodyne Instrument for the Far Infrared (HIFI) on-board Herschel. The line emission from the fundamental transition of water at 557 GHz was searched for and an upper ... [more ▼]

176P/LINEAR was observed with the Heterodyne Instrument for the Far Infrared (HIFI) on-board Herschel. The line emission from the fundamental transition of water at 557 GHz was searched for and an upper limit on its production was inferred. [less ▲]

Detailed reference viewed: 18 (2 ULg)
Full Text
See detailSpectra of 13 lensed quasars (Sluse+, 2012)
Sluse, D.; Hutsemekers, Damien ULg; Courbin, F. et al

Textual, factual or bibliographical database (2012)

Extracted flux calibrated spectra of 13 lensed quasars following the methodology described in Sect. 2.1. of the oaoer. The data were obtained with the FORS spectrograph at VLT in multi-object spectroscopy ... [more ▼]

Extracted flux calibrated spectra of 13 lensed quasars following the methodology described in Sect. 2.1. of the oaoer. The data were obtained with the FORS spectrograph at VLT in multi-object spectroscopy mode. The typical wavelength coverage is from 4200 to 8200Å. The data concern the following objects: HE0047-1756 (HE0047), Q0142-100 (Q0142), SDSSJ0246-0825 (SDSS0246), HE0435-1223 (HE0435), SDSSJ0806+2006 (SDSS0806), FBQ0951+2635 (FBQ0951), BRI0952-0115 (BRI0952), SDSSJ1138+0314 (J1138), J1226-0006 (J1226), SDSSJ1335+0118 (J1335), Q1355-2257 (Q1355), WFI2033-4723 (WFI2033), and HE2149-2745 (HE2149). For each object, we provide the 1D flux calibrated spectrum of the 2 individual images in the slit. In addition, we also provide the 2D reduced spectrum and corresponding 1σ error frame (corresponding files are named "objectname[SUB]data" and "objectname[/SUB]err"), and the 2D processed spectra associated to the deconvolution, as shown in Fig.1 of the paper. These processed 2D spectra are the deconvolved frame ("[SUB]dec"), the extended component of the flux emission ("[/SUB]ext") and the residual frame in σ units ("_res") corresponding to panel (b), (c) and (d) of Fig.1. A pdf file file similar to Fig.1 is also provided for each object. (4 data files). [less ▲]

Detailed reference viewed: 21 (0 ULg)
Full Text
Peer Reviewed
See detailCharacterizing Lenses and Lensed Stars of High-magnification Single-lens Gravitational Microlensing Events with Lenses Passing over Source Stars
Choi, J.-Y.; Shin, I.-G.; Park, S.-Y. et al

in Astrophysical Journal (2012), 751

We present the analysis of the light curves of nine high-magnification single-lens gravitational microlensing events with lenses passing over source stars, including OGLE-2004-BLG-254, MOA-2007-BLG-176 ... [more ▼]

We present the analysis of the light curves of nine high-magnification single-lens gravitational microlensing events with lenses passing over source stars, including OGLE-2004-BLG-254, MOA-2007-BLG-176, MOA-2007-BLG-233/OGLE-2007-BLG-302, MOA-2009-BLG-174, MOA-2010-BLG-436, MOA-2011-BLG-093, MOA-2011-BLG-274, OGLE-2011-BLG-0990/MOA-2011-BLG-300, and OGLE-2011-BLG-1101/MOA-2011-BLG-325. For all of the events, we measure the linear limb-darkening coefficients of the surface brightness profile of source stars by measuring the deviation of the light curves near the peak affected by the finite-source effect. For seven events, we measure the Einstein radii and the lens-source relative proper motions. Among them, five events are found to have Einstein radii of less than 0.2 mas, making the lenses very low mass star or brown dwarf candidates. For MOA-2011-BLG-274, especially, the small Einstein radius of θ[SUB]E[/SUB] ~ 0.08 mas combined with the short timescale of t [SUB]E[/SUB] ~ 2.7 days suggests the possibility that the lens is a free-floating planet. For MOA-2009-BLG-174, we measure the lens parallax and thus uniquely determine the physical parameters of the lens. We also find that the measured lens mass of ~0.84 M [SUB]&sun;[/SUB] is consistent with that of a star blended with the source, suggesting that the blend is likely to be the lens. Although we did not find planetary signals for any of the events, we provide exclusion diagrams showing the confidence levels excluding the existence of a planet as a function of the separation and mass ratio. [less ▲]

Detailed reference viewed: 19 (4 ULg)
Full Text
Peer Reviewed
See detailThe HARPS search for southern extra-solar planets XXXV. Super-Earths around the M-dwarf neighbors Gl433 and Gl667C
Delfosse, X.; Bonfils, X.; Forveille, T. et al

in Astronomy and Astrophysics (2012), 553

Context. M dwarfs have often been found to have super-Earth planets with short orbital periods. These stars are thus preferential targets in searches for rocky or ocean planets in the solar neighborhood ... [more ▼]

Context. M dwarfs have often been found to have super-Earth planets with short orbital periods. These stars are thus preferential targets in searches for rocky or ocean planets in the solar neighborhood. Aims: Our research group recently announced the discovery of one and two low-mass planets around the M1.5V stars Gl 433 and Gl 667C, respectively. We found these planets with the HARPS spectrograph on the ESO 3.6-m telescope at La Silla Observatory, from observations obtained during the guaranteed time observing program of that instrument. Methods: We obtained additional HARPS observations of those two stars, for a total of 67 and 179 radial velocity measurements for Gl 433 and Gl 667C, respectively, and present here an orbital analysis of these extended data sets and our main conclusions about both planetary systems. Results: One of the three planets, Gl 667Cc, has a mass of only M2sini ~ 4.25 M⊕ and orbits in the central habitable zone of its host star. It receives only 10% less stellar energy from Gl 667C than the Earth receives from the Sun. However, planet evolution in the habitable zone can be very different if the host star is a M dwarf or a solar-like star, without necessarily questioning the presence of water. The two other planets, Gl 433b and Gl 667Cb, both have M2sini of ~5.5 M⊕ and periods of ~7 days. The radial velocity measurements of both stars contain longer timescale signals, which we fit with longer period Keplerians. For Gl 433, the signal probably originates in a magnetic cycle, while data of longer time span will be needed before conclusive results can be obtained for Gl 667C. The metallicity of Gl 433 is close to solar, while Gl 667C is metal poor with [Fe/H] ~ -0.6. This reinforces the recent conclusion that the occurrence of super-Earth planets does not strongly correlate with the stellar metallicity. [less ▲]

Detailed reference viewed: 22 (1 ULg)
Full Text
See detailAbstract numeration systems
Charlier, Emilie ULg

Scientific conference (2012, May)

Abstract numeration systems were introduced in 2001 by P. Lecomte and M. Rigo. This new way to represent numbers generalizes that of usual positional numeration systems such as integer base numeration ... [more ▼]

Abstract numeration systems were introduced in 2001 by P. Lecomte and M. Rigo. This new way to represent numbers generalizes that of usual positional numeration systems such as integer base numeration systems and linear numeration systems. Some standard properties are preserved in this wider framework though some others are not. Yet, the advantages of these systems stem from their great generality: current research on this subject strives to highlight the properties that are independent of the target numeration system, such as properties related to the complexity of the numeration language. In this talk I will introduce this topic. In particular, I will present many open questions in the area and highlight the connections with combinatorics on words. [less ▲]

Detailed reference viewed: 32 (2 ULg)
Full Text
See detailAn introduction to abstract numeration systems
Charlier, Emilie ULg

Scientific conference (2012, May)

Abstract numeration systems were introduced in 2001 by P. Lecomte and M. Rigo. This new way to represent numbers generalizes that of usual positional numeration systems such as integer base numeration ... [more ▼]

Abstract numeration systems were introduced in 2001 by P. Lecomte and M. Rigo. This new way to represent numbers generalizes that of usual positional numeration systems such as integer base numeration systems and linear numeration systems. Some standard properties are preserved in this wider framework though some others are not. Yet, the advantages of these systems stem from their great generality: current research on this subject strives to highlight the properties that are independent of the target numeration system, such as properties related to the complexity of the numeration language. In this talk I will introduce this topic. In particular, I will present many open questions in the area and highlight the connections with combinatorics on words. [less ▲]

Detailed reference viewed: 37 (1 ULg)