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See detailA detailed X-ray investigation of ζ Puppis. I. The dataset and some preliminary results
Nazé, Yaël ULg; Flores, C. A.; Rauw, Grégor ULg

in Astronomy and Astrophysics (2012), 538

<BR /> Aims: One of the closest and brightest massive stars, ζ Puppis, was the first early-type object observed by the current generation of X-ray observatories. These observations provided some ... [more ▼]

<BR /> Aims: One of the closest and brightest massive stars, ζ Puppis, was the first early-type object observed by the current generation of X-ray observatories. These observations provided some surprising results, partly confirming the theoretical predictions while simultaneously unveiling some problematic mismatches with expectations. In this series of papers, we perform a thorough study of ζ Puppis in X-rays, using a decade of XMM-Newton observations. <BR /> Methods: The star ζ Puppis was observed 18 times by XMM-Newton, totaling 1 Ms in exposure. This provides the highest quality high-resolution X-ray spectrum of a massive star to date, as well as a perfect dataset for studying X-ray variability in an "archetype" object. <BR /> Results: This first paper reports on the data reduction of this unique dataset and provides a few preliminary results. On the one hand, analysis of EPIC low-resolution spectra shows the star to have a remarkably stable X-ray emission from one observation to the next. On the other hand, fitting by a wind model of individual line profiles recorded by RGS confirms the wavelength dependence of the line morphology. Based on observations collected with XMM-Newton, an ESA Science Mission with instruments and contributions directly funded by ESA Member States and the USA (NASA).Table 1 is available in electronic form at <A href="http://www.aanda.org">http://www.aanda.org</A> [less ▲]

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See detailA Detailed X-Ray Investigation of ζ Puppis. II. The Variability on Short and Long Timescales
Nazé, Yaël ULg; Oskinova, Lidia M.; Gosset, Eric ULg

in Astrophysical Journal (2013), 763

Stellar winds are a crucial component of massive stars, but their exact properties still remain uncertain. To shed some light on this subject, we have analyzed an exceptional set of X-ray observations of ... [more ▼]

Stellar winds are a crucial component of massive stars, but their exact properties still remain uncertain. To shed some light on this subject, we have analyzed an exceptional set of X-ray observations of ζ Puppis, one of the closest and brightest massive stars. The sensitive light curves that were derived reveal two major results. On the one hand, a slow modulation of the X-ray flux (with a relative amplitude of up to 15% over 16 hr in the 0.3-4.0 keV band) is detected. Its characteristic timescale cannot be determined with precision, but amounts from one to several days. It could be related to corotating interaction regions, known to exist in ζ Puppis from UV observations. Hour-long changes, linked to flares or to the pulsation activity, are not observed in the last decade covered by the XMM observations; the 17 hr tentative period, previously reported in a ROSAT analysis, is not confirmed either and is thus transient, at best. On the other hand, short-term changes are surprisingly small (<1% relative amplitude for the total energy band). In fact, they are compatible solely with the presence of Poisson noise in the data. This surprisingly low level of short-term variability, in view of the embedded wind-shock origin, requires a very high fragmentation of the stellar wind, for both absorbing and emitting features (>10[SUP]5[/SUP] parcels, comparing with a two-dimensional wind model). This is the first time that constraints have been placed on the number of clumps in an O-type star wind and from X-ray observations. Based on observations collected with XMM-Newton, an ESA Science Mission with instruments and contributions directly funded by ESA Member States and the USA (NASA). [less ▲]

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See detailA detailed X-ray investigation of ζ Puppis. III. Spectral analysis of the whole RGS spectrum
Hervé, Anthony ULg; Rauw, Grégor ULg; Nazé, Yaël ULg

in Astronomy and Astrophysics (2013), 551

Context. ζ Pup is the X-ray brightest O-type star of the sky. This object was regularly observed with the RGS instrument onboard XMM-Newton for calibration purposes, which led to an unprecedented set of ... [more ▼]

Context. ζ Pup is the X-ray brightest O-type star of the sky. This object was regularly observed with the RGS instrument onboard XMM-Newton for calibration purposes, which led to an unprecedented set of high-quality spectra. <BR /> Aims: We have previously reduced and extracted this data set and integrated it into the most detailed high-resolution X-ray spectrum of any early-type star so far. Here we present the analysis of this spectrum, taking into account for the presence of structures in the stellar wind. <BR /> Methods: For this purpose, we used our new modeling tool that allows fitting the entire spectrum with a multi-temperature plasma. We illustrate the impact of a proper treatment of the radial dependence of the X-ray opacity of the cool wind on the best-fit radial distribution of the temperature of the X-ray plasma. <BR /> Results: The best-fit of the RGS spectrum of ζ Pup is obtained assuming no porosity. Four plasma components at temperatures between 0.10 and 0.69 keV are needed to adequately represent the observed spectrum. Whilst the hardest emission is concentrated between ~3 and 4 R[SUB]∗[/SUB], the softer emission starts already at 1.5 R[SUB]∗[/SUB] and extends to the outer regions of the wind. <BR /> Conclusions: The inferred radial distribution of the plasma temperatures agrees rather well with theoretical expectations. The mass-loss rate and CNO abundances corresponding to our best-fit model also agree quite well with the results of recent studies of ζ Pup in the UV and optical domain. Based on observations collected with XMM-Newton, an ESA Science Mission with instruments and contributions directly funded by ESA Member States and the USA (NASA). [less ▲]

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See detailDétails et catastrophes littéraires
Delville, Michel ULg

in Belloi, Livio; Hagelstein, Maud (Eds.) La mécanique du détail (2007, October 28)

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See detailDetails on DARWIN and the Search for Extrasolar Planets
Kaltenegger, L.; Fridlund, M.; Absil, Olivier ULg

in Deming, Drake; Seager, Sara (Eds.) Scientific Frontiers in Research on Extrasolar Planets (2003)

The direct detection of an earth-like planet close to its parent star is challenging because the signal detected from the parent star is between 10[SUB]9[/SUB] and 10[SUB]6[/SUB] times brighter than the ... [more ▼]

The direct detection of an earth-like planet close to its parent star is challenging because the signal detected from the parent star is between 10[SUB]9[/SUB] and 10[SUB]6[/SUB] times brighter than the signal of a planet in the visual and infrared (IR), respectively. Future space based missions like DARWIN and TPF concentrate on the region between 6 and 18 microns, a region that contains the carbon dioxide, water, and ozone spectral features of the atmosphere. Using several small collecting telescopes and a beam combiner allows us to build an instrument with an angular resolution normally associated with monolithic telescopes of much larger diameters. The relative positions of the telescopes, forming the interferometer, are selected such that when the optical signals, collected by the individual telescopes, are coherently combined, the small angular distance between the planet and the star can be resolved. Different configurations of the free flying interferometer array influence the performance of the nulling array. The concepts for space nulling interferometers and the influence of different schemes of beam combination on the detected signal are investigated. The contribution of background noise to the detected signal is examined. [less ▲]

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See detailDetección del BLV en muestras de semen de toros seropositivos
Rossich, L.; Gutiérrez, G.; Rodriguez, Sabrina ULg et al

Poster (2007, December 02)

Detección del BLV en muestras de semen de toros seropositivos Rossich Luciano1; Gutierrez Geronimo1; Rodriguez Sabrina1; Lefebvre Eduardo2; Trono Karina1; Dus Santos Maria Jose1. (1) Instituto de ... [more ▼]

Detección del BLV en muestras de semen de toros seropositivos Rossich Luciano1; Gutierrez Geronimo1; Rodriguez Sabrina1; Lefebvre Eduardo2; Trono Karina1; Dus Santos Maria Jose1. (1) Instituto de Virología, CICVyA, INTA-Castelar. CC 77. Buenos Aires, Argentina. (2) Centro de Inseminación Artificial La Elisa. Argentina. La principal ruta de transmisión del Virus de la Leucosis Bovina (BLV) es horizontal y esta dada por la exposición directa de fluidos biológicos contaminados con linfocitos infectados; principalmente sangre. A pesar de que antígenos virales y ADN proviral han sido identificados en semen, leche y calostro; la transmisión natural a través de estas secreciones no ha sido demostrada. El impacto sanitario y económico de la infección por BLV esta asociada con la interferencia en el movimiento internacional del ganado vacuno y su germoplasma. Datos experimentales soportan la improbabilidad de que el semen congelado de toros seropositivos para BLV puedan infectar vacas receptoras, sin embargo, aun hoy existen restricciones para la comercialización de semen de animales infectados. Dado que no existe vacuna ni tratamiento aplicable, la erradicación y control de la enfermedad esta exclusivamente basada en el diagnóstico temprano y segregación de los animales infectados. En este contexto la especificidad y la sensibilidad del diagnóstico utilizado constituyen un punto crítico. Hemos desarrollado previamente una PCR con alta sensibilidad y especificidad para detectar el genoma de BLV en muestras de semen congelado. El objetivo de este trabajo es el estudio del patrón de excreción natural de BLV en semen. Muestras de semen congelado de 30 toros seropositvos fueron analizados. Fue posible detectar ADN proviral en 144 de 752 muestras. La detección del genoma del BLV ha ocurrido en varias colecciones pero en forma alternada con períodos de no detección. Adicionalmente, la presencia de ARN proviral en sangre y muestras de sangre fue evaluada. [less ▲]

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See detailDétecter et contrôler l'herpèsvirose caprine
Thiry, Julien ULg; Thiry, Etienne ULg

in Point Vétérinaire (2008), 285

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See detailDétecter le cancer de la vessie à partir d’échantillons d’urine
Waltregny, David ULg; Joniau, Steven; Bierau, Katia et al

Scientific conference (2009, October)

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See detailLe détecteur de mensonges à la rescousse de la défense ?
Monville, Pierre ULg

in Revue de Jurisprudence de Liège, Mons et Bruxelles (2002)

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See detailDétecteurs de candidats au djihad - 150 travailleurs sociaux ont commencé une formation en "déradicalisation"
Ponciau, Ludivine; Garcet, Serge ULg

Article for general public (2015)

L'article propose une analyse de la politique de formation du secteur de l'aide à la jeunesse en matière de "déradicalisation" et un entretien dans lequel nous donnons notre point de vue d'expert.

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See detailDetectie van enteropathogene Escherichia coli bij vleeskonijnen : Een nieuwe diagnostische test
Vandekerckhove, D; Chow, TT; Callebaut, A et al

Book published by Ministère de l'Agriculture et des Classes Moyennes (2001)

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See detailDetectie, pathogenese, en etiologie van longfunctieveranderingen by de verouderende hond, met speciale aandacht voor het surfactant systeem
Haagsman, H. P.; Clercx, Cécile ULg; van den Brom, W. E. et al

in Fungo Dwarsverband V.O. Retraite - Eymond-Ville - Netherlands - Novembre 1985 (1985, November)

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See detailDetecting and modelling the magnetic field of the β Cephei star V 2052 Ophiuchi
Neiner, C.; Alecian, E.; Briquet, Maryline ULg et al

in Astronomy and Astrophysics (2012), 537

<BR /> Aims: Following the indirect detection of a magnetic field in the β Cephei star <ASTROBJ>V 2052 Oph</ASTROBJ> by Neiner and collaborators in 2003 with the Musicos spectropolarimeter, we remeasured ... [more ▼]

<BR /> Aims: Following the indirect detection of a magnetic field in the β Cephei star <ASTROBJ>V 2052 Oph</ASTROBJ> by Neiner and collaborators in 2003 with the Musicos spectropolarimeter, we remeasured the magnetic field of this star to attempt to directly confirm the detection of a magnetic field and study its configuration in greater detail. <BR /> Methods: We used the Narval spectropolarimeter installed at TBL (Pic du Midi, France), which is about 20 times more efficient than the Musicos spectropolarimeter. We applied the least-squares deconvolution (LSD) technique to various groups of lines to measure the circular polarisation of the light coming from <ASTROBJ>V 2052 Oph</ASTROBJ>. We synthesized the measured Stokes V profiles with a centred and off-centred dipole model. <BR /> Results: For the first time, we clearly detect the Zeeman signature in the Stokes V profiles of <ASTROBJ>V 2052 Oph</ASTROBJ> and thus directly prove the presence of a magnetic field in this star. The modulation with the rotation period is also confirmed and reflects an oblique dipole field. Thanks to the small error bars on the measurements, we are able to study the behaviour of different groups of lines and the centring of the dipole in the star. We find that the dipole is most likely off-centred along the magnetic axis and that He spots are present at the surface next to the magnetic axis. <BR /> Conclusions: We conclude that <ASTROBJ>V 2052 Oph</ASTROBJ> is a magnetic He-strong β Cep star, with a dipole field, probably off-centred, with B[SUB]pol[/SUB] ~ 400 G and He patches close to the magnetic poles. Based on observations obtained with the Narval spectropolarimeter at the Télescope Bernard Lyot, Observatoire du Pic du Midi, France. [less ▲]

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See detailDetecting awareness in impaired states of consciousness
Vanhaudenhuyse, Audrey ULg

Conference (2007)

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See detailDetecting awareness in patients with disorders of consciousness using a hybrid brain–computer interface
Pan, Jiahui; Xie, Qiuyou; He, Yanbin et al

in Journal of Neural Engineering (2014)

Objective. The bedside detection of potential awareness in patients with disorders of consciousness (DOC) currently relies only on behavioral observations and tests; however, the misdiagnosis rates in ... [more ▼]

Objective. The bedside detection of potential awareness in patients with disorders of consciousness (DOC) currently relies only on behavioral observations and tests; however, the misdiagnosis rates in this patient group are historically relatively high. In this study, we proposed a visual hybrid brain–computer interface (BCI) combining P300 and steady-state evoked potential (SSVEP) responses to detect awareness in severely brain injured patients. Approach. Four healthy subjects, seven DOC patients who were in a vegetative state (VS, n = 4) or minimally conscious state (MCS, n = 3), and one locked-in syndrome (LIS) patient attempted a command-following experiment. In each experimental trial, two photos were presented to each patient; one was the patientʼs own photo, and the other photo was unfamiliar. The patients were instructed to focus on their own or the unfamiliar photos. The BCI system determined which photo the patient focused on with both P300 and SSVEP detections. Main results. Four healthy subjects, one of the 4 VS, one of the 3 MCS, and the LIS patient were able to selectively attend to their own or the unfamiliar photos (classification accuracy, 66–100%). Two additional patients (one VS and one MCS) failed to attend the unfamiliar photo (50–52%) but achieved significant accuracies for their own photo (64–68%). All other patients failed to show any significant response to commands (46–55%). Significance. Through the hybrid BCI system, command following was detected in four healthy subjects, two of 7 DOC patients, and one LIS patient. We suggest that the hybrid BCI system could be used as a supportive bedside tool to detect awareness in patients with DOC. [less ▲]

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See detailDetecting Awareness in the Vegetative State
Owen, Adrian; Coleman, Martin; Boly, Mélanie ULg et al

in Science (2006)

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See detailDetecting consciousness in a total Locked-in syndrome: an active event related paradigm
Schnakers, Caroline ULg; Perrin, Fabien; Schabus, Manuel et al

in Neurocase : Case Studies in Neuropsychology, Neuropsychiatry & Behavioural Neurology (2009), 25

Total locked-in syndrome is characterized by tetraplegia, anarthria and paralysis of eye motility. In this study, consciousness was detected in a 21-year-old woman who presented a total locked-in syndrome ... [more ▼]

Total locked-in syndrome is characterized by tetraplegia, anarthria and paralysis of eye motility. In this study, consciousness was detected in a 21-year-old woman who presented a total locked-in syndrome after a basilar artery thrombosis (49 days post-injury) using an active event-related paradigm. The patient was presented sequences of names containing the patient's own name and other names. The patient was instructed to count her own name or to count another target name. Similar to 4 age- and gender-matched healthy controls, the P3 response recorded for the voluntarily counted own name was larger than while passively listening. This P3 response was observed 14 days before the first behavioral signs of consciousness. This study shows that our active event-related paradigm allowed to identify voluntary brain activity in a patient who would behaviorally be diagnosed as comatose. [less ▲]

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