Browsing
     by title


0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

or enter first few letters:   
OK
Full Text
Peer Reviewed
See detailImaging of super-fast dynamics and flow instabilities of superconducting vortices
Embon, L.; Anahory, Y.; Jelic, Zeljko ULg et al

in Nature Communications (2017), 8

Quantized magnetic vortices driven by electric current determine key electromagnetic properties of superconductors. While the dynamic behavior of slow vortices has been thoroughly investigated, the ... [more ▼]

Quantized magnetic vortices driven by electric current determine key electromagnetic properties of superconductors. While the dynamic behavior of slow vortices has been thoroughly investigated, the physics of ultrafast vortices under strong currents remains largely unexplored. Here, we use a nanoscale scanning superconducting quantum interference device to image vortices penetrating into a superconducting Pb film at rates of tens of GHz and moving with velocities of up to tens of km/s, which are not only much larger than the speed of sound but also exceed the pair-breaking speed limit of superconducting condensate. These experiments reveal formation of mesoscopic vortex channels which undergo cascades of bifurcations as the current and magnetic field increase. Our numerical simulations predict metamorphosis of fast Abrikosov vortices into mixed Abrikosov-Josephson vortices at even higher velocities. This work offers an insight into the fundamental physics of dynamic vortex states of superconductors at high current densities, crucial for many applications. [less ▲]

Detailed reference viewed: 32 (2 ULg)
Full Text
Peer Reviewed
See detailImaging Orbitals by Ionization or Electron Attachment: The Role of Dyson Orbitals
Mignolet, Benoît ULg; Kus, Tomasz ULg; Remacle, Françoise ULg

in Joachim, C.; Grill, L. (Eds.) Imaging and Manipulating Molecular Orbitals (2013)

Detailed reference viewed: 27 (2 ULg)
Full Text
Peer Reviewed
See detailImaging osteoarthritis using (18F)FPRGD2 PET/CT : observation and potential application.
WITHOFS, Nadia ULg; ALVAREZ MIEZENTSEVA, Victoria ULg; SIMONI, Paolo ULg et al

in Journal of Nuclear Medicine (The) (2013), 54(SUPPL), 250

Detailed reference viewed: 17 (3 ULg)
Full Text
See detailImaging polarimeters based on Liquid Crystal Variable Retarders: an emergent technology for space instrumentation
Alvarez-Herrero, A.; Uribe-Patarroyo, N.; Garcia Parejo, P. et al

in Show, J. A.; Scott Tyo, J. (Eds.) Proc. SPIE Vol 8160 on Polarization Science and Remote Sensing V (2011, September 09)

Detailed reference viewed: 67 (1 ULg)
Full Text
See detailImaging protoplanets: observing transition disks with non-redundant masking
Sallum, S.; Eisner, J.; Close, L. M. et al

in Optical and Infrared Interferometry and Imaging V (2016)

Transition disks, protoplanetary disks with inner clearings, are promising objects in which to directly image forming planets. The high contrast imaging technique of non-redundant masking is well posed to ... [more ▼]

Transition disks, protoplanetary disks with inner clearings, are promising objects in which to directly image forming planets. The high contrast imaging technique of non-redundant masking is well posed to detect planetary mass companions at several to tens of AU in nearby transition disks. We present non-redundant masking observations of the T Cha and LkCa 15 transition disks, both of which host posited sub-stellar mass companions. However, due to a loss of information intrinsic to the technique, observations of extended sources (e.g. scattered light from disks) can be misinterpreted as moving companions. We discuss tests to distinguish between these two scenarios, with applications to the T Cha and LkCa 15 observations. We argue that a static, forward-scattering disk can explain the T Cha data, while LkCa 15 is best explained by multiple orbiting companions. [less ▲]

Detailed reference viewed: 13 (4 ULg)
Peer Reviewed
See detailImaging serotonin-S2 receptors in humans with PET and the selective S2 antagonist [18F]altanserin. Preliminary results.
Sadzot, Bernard ULg; Lemaire, Christian ULg; Cantineau, R. et al

in Journal of Nuclear Medicine : Official Publication, Society of Nuclear Medicine (1990, June 19), 31

Detailed reference viewed: 13 (2 ULg)
See detailImaging techniques
Calvo Del Castillo, Helena ULg; Cervera Xicotencatl, Ariadna; Oger, Cécile

Conference (2010)

Detailed reference viewed: 23 (3 ULg)
Full Text
Peer Reviewed
See detailImaging technologies to understand grinding at particle scale in a UG-2 platinum ore processing plant
Leroy, Sophie ULg; Pirard, Eric ULg

in XXVI INTERNATIONAL MINERAL PROCESSING CONGRESS (IMPC) 2012 PROCEEDINGS / NEW DELHI, INDIA / 24 - 28 SEPTEMBER 2012 (2012, September)

Detailed reference viewed: 87 (31 ULg)
Peer Reviewed
See detailImaging the Central Nervous System
Bodart, Olivier ULg; Laureys, Steven ULg

in Webb, A.; Angus, D.; Finfer, S. (Eds.) et al Oxford Textbook of Critical Care, Second Edition (2016)

Detailed reference viewed: 279 (33 ULg)
See detailImaging the equine tendons
Busoni, Valeria ULg

in Canifelis Hippos Proceedings 2011 (2011)

Detailed reference viewed: 50 (15 ULg)
Full Text
Peer Reviewed
See detailImaging the Inner and Outer Gaps of the Pre-transitional Disk of HD 169142 at 7 mm
Osorio, Mayra; Anglada, Guillem; Carrasco-González, Carlos et al

in Astrophysical Journal Letters (2014), 791

We present Very Large Array observations at 7 mm that trace the thermal emission of large dust grains in the HD 169142 protoplanetary disk. Our images show a ring of enhanced emission of radius ~25-30 AU ... [more ▼]

We present Very Large Array observations at 7 mm that trace the thermal emission of large dust grains in the HD 169142 protoplanetary disk. Our images show a ring of enhanced emission of radius ~25-30 AU, whose inner region is devoid of detectable 7 mm emission. We interpret this ring as tracing the rim of an inner cavity or gap, possibly created by a planet or a substellar companion. The ring appears asymmetric, with the western part significantly brighter than the eastern one. This azimuthal asymmetry is reminiscent of the lopsided structures that are expected to be produced as a consequence of trapping of large dust grains. Our observations also reveal an outer annular gap at radii from ~40 to ~70 AU. Unlike other sources, the radii of the inner cavity, the ring, and the outer gap observed in the 7 mm images, which trace preferentially the distribution of large (millimeter/centimeter sized) dust grains, coincide with those obtained from a previous near-infrared polarimetric image, which traces scattered light from small (micron-sized) dust grains. We model the broadband spectral energy distribution and the 7 mm images to constrain the disk physical structure. From this modeling we infer the presence of a small (radius ~0.6 AU) residual disk inside the central cavity, indicating that the HD 169142 disk is a pre-transitional disk. The distribution of dust in three annuli with gaps in between them suggests that the disk in HD 169142 is being disrupted by at least two planets or substellar objects. [less ▲]

Detailed reference viewed: 16 (1 ULg)
Full Text
See detailImaging the inner regions of debris disks with near-infrared interferometry
Defrere, Denis ULg; Absil, Olivier ULg; Augereau, J. C. et al

in EPSC-DPS Joint Meeting 2011 (2011, October 01)

Most debris disks resolved so far show extended structures located at tens to hundreds AU from the host star, and are more analogous to our solar system's dusty Kuiper belt than to the AU-scale zodiacal ... [more ▼]

Most debris disks resolved so far show extended structures located at tens to hundreds AU from the host star, and are more analogous to our solar system's dusty Kuiper belt than to the AU-scale zodiacal disk inside our solar system's asteroid belt. Over the last few years however, a few hot debris disks have been detected around a handful of main sequence stars thanks to the advance of infrared interferometry. The grain populations derived from these observations are quite intriguing, as they point towards very high dust replenishment rates, high cometary activity or major collisional events. In this talk, we review the ongoing efforts to detect bright exozodiacal disks with precision near-infrared interferometry in both hemispheres with CHARA/FLUOR and VLTI/PIONIER. We discuss preliminary statistical trends on the occurrence of bright exozodi around nearby main sequence stars and show how this information could be used to constrain the global architecture and evolution of debris disks. [less ▲]

Detailed reference viewed: 24 (0 ULg)
Full Text
See detailImaging the mechanisms involved in abdominal aortic aneurysms rupture; a step towards patient-specific risk assessment
NCHIMI LONGANG, Alain ULg

Doctoral thesis (2015)

Introduction The general context of this dissertation is to evaluate patient-specifi c approaches to the risk of rupture of abdominal aortic aneurysm (AAA), using imaging techniques with ability to assess ... [more ▼]

Introduction The general context of this dissertation is to evaluate patient-specifi c approaches to the risk of rupture of abdominal aortic aneurysm (AAA), using imaging techniques with ability to assess biological processes. Following a thorough description of available imaging techniques, our work is divided in two main research objectives, namely: (i) to provide greater clinical value to existing but unproven imaging concepts, and (ii) to suggest new concepts for improved AAA risk of rupture assessment. Methods The fi rst research objective evaluated how far imaging biological activities using 18F-Fluorodeoxyglucose (FDG) Positron Emission Tomography (PET) and modeling wall stress using fi nite element simulations (FES) may help clinical decisionmaking in patients with AAA, and what would be their incremental value as compared to diameter-based patient management algorithms. On a patient basis, clinical outcomes were evaluated with regard to FDG PET and FES signaling. Further, the concept of AAA risk-equivalent diameter using FES was described and retrospectively validated using data from large multicenter trials. The second research objective included the assessment of the biological activities of the intraluminal thrombus (ILT) and the demonstration of its deleterious role in AAA using multimodality imaging. A special emphasis was put on the ability of magnetic resonance imaging (MRI) to monitor the biological activities of ILT without exogenous contrast, by evaluating its iron content. Results Increased FDG uptake was a diameter-independent marker of AAA-related events over 2 years. Missing dichotomy prevented such a fi nding for increased wall stress, although its correlation with increased FDG uptake indicates a potentially comparable value in terms of risk management. Wall metabolism is infl uenced by patient-specifi c susceptibility factors, indicating hereditary or acquired alteration of the biological responses to wall stress. The concept of risk-equivalent diameters on FES links biomechanical estimates to basic conclusions drawn from large diameter-based clinical AAA trials. Our retrospective and diameter-adjusted validation analysis verifi ed that biomechanical risk indicators are higher in ruptured than non-ruptured AAAs. Part of the FDG uptake is associated with biological activity along the luminal surface of the ILT, where we experimentally demonstrated phagocytosis of superparamagnetic iron oxide on MRI , both ex vivo and in vivo. This phagocytosis is correlated with the abundance of leukocytes and proteolytic activity. In addition, unenhanced MRI appearances resulting from the endogenous iron distribution within ILT also relate to these biological activities. Lastly, multimodality imaging was used to confi rm the concept of the deleterious role of the ILT in AAA growth in a model of AAA by infusion of elastase in the rat. Conclusion MRI and FDG PET are capable of evidencing and quantifying in vivo some of the notoriously deleterious biological processes taking place in the aneurysmal sac, especially related to the entrapped phagocytes and red blood cells in ILT and the periadventitial infl ammatory response. The central role played by ILT and its biological activities was demonstrated in vivo using several imaging techniques. The clinical value of imaging these biological activities is epitomized by a diameterindependent 2-year increased risk of event in AAA with increased wall metabolism. [less ▲]

Detailed reference viewed: 202 (13 ULg)
Full Text
Peer Reviewed
See detailImaging the solar corona in the EUV
Delaboudiniere, J.-P.; Stern, R. A.; Maucherat, A. et al

in Advances in Space Research (1997), 20

The SOHO (SOlar and Heliospheric Observatory) satellite was launched on December 2nd 1995. After arriving at the Earth-Sun (L1) Lagrangian point on February 14th 1996, it began to continuously observe the ... [more ▼]

The SOHO (SOlar and Heliospheric Observatory) satellite was launched on December 2nd 1995. After arriving at the Earth-Sun (L1) Lagrangian point on February 14th 1996, it began to continuously observe the Sun. As one of the instruments onboard SOHO, the EIT (Extreme ultraviolet Imaging Telescope) images the Sun's corona in 4 EUV wavelengths. The He II filter at 304 AË images the chromosphere and the base of the transition region at a temperature of 5 - 8 x 10^4 K; the Fe IX-X filter at 171 AË images the corona at a temperature of ~ 1.3 x 10^6 K; the Fe XII filter at 195 AË images the quiet corona outside coronal holes at a temperature of ~ 1.6 x 10^6 K; and the Fe XV filter at 284 AË images active regions with a temperature of ~ 2.0 x 10^6 K. About 5000 images have been obtained up to the present. In this paper, we describe also some aspects of the telescope and the detector performance for application in the observations. Images and movies of all the wavelengths allow a look at different phenomena present in the Sun's corona, and in particular, magnetic field reconnection. [less ▲]

Detailed reference viewed: 81 (7 ULg)
Full Text
Peer Reviewed
See detailImaging the Statics and Dynamics of Superconducting Vortices and Antivortices Induced by Magnetic Microdisks
Kramer, R. B. G.; Silhanek, Alejandro ULg; Gillijns, W. et al

in Physical Review X (2011), 1(2), 021004

If a magnet of microscopic dimensions is brought in close proximity to a superconductor, the quantized nature of their interaction due to the creation of flux quanta in the superconducting system becomes ... [more ▼]

If a magnet of microscopic dimensions is brought in close proximity to a superconductor, the quantized nature of their interaction due to the creation of flux quanta in the superconducting system becomes noticeable. Herein, we directly image, via scanning Hall microscopy, the vortex-antivortex pairs in a superconducting film created by micromagnets. The number of antivortices at equilibrium conditions can be changed either by tuning the magnetic moment of the magnets or by annihilation with externally induced vortices. We demonstrate that small ac field excitations shake the antivortices sitting next to the micromagnets whereas no sizable motion is observed for the vortices sitting on top of the magnets, clearly revealing the different mobility of these two vortex species. A metastable state, which is obtained by applying a field after the system has been cooled down below the superconducting transition, shows a complex graded distribution of coexisting vortices and antivortices forming an intertwined critical state. [less ▲]

Detailed reference viewed: 17 (1 ULg)
Full Text
See detailImaging the statics and dynamics of vortex-antivortex molecules
Silhanek, Alejandro ULg

Conference (2011, September)

Detailed reference viewed: 14 (1 ULg)
Full Text
Peer Reviewed
See detailImaging the where and when of tic generation and resting state networks in adult Tourette patients.
Neuner, Irene; Werner, Cornelius J.; Arrubla Martinez, Jorge Andres ULg et al

in Frontiers in Human Neuroscience (2014), 8

INTRODUCTION: Tourette syndrome (TS) is a neuropsychiatric disorder with the core phenomenon of tics, whose origin and temporal pattern are unclear. We investigated the When and Where of tic generation ... [more ▼]

INTRODUCTION: Tourette syndrome (TS) is a neuropsychiatric disorder with the core phenomenon of tics, whose origin and temporal pattern are unclear. We investigated the When and Where of tic generation and resting state networks (RSNs) via functional magnetic resonance imaging (fMRI). METHODS: Tic-related activity and the underlying RSNs in adult TS were studied within one fMRI session. Participants were instructed to lie in the scanner and to let tics occur freely. Tic onset times, as determined by video-observance were used as regressors and added to preceding time-bins of 1 s duration each to detect prior activation. RSN were identified by independent component analysis (ICA) and correlated to disease severity by the means of dual regression. RESULTS: Two seconds before a tic, the supplementary motor area (SMA), ventral primary motor cortex, primary sensorimotor cortex and parietal operculum exhibited activation; 1 s before a tic, the anterior cingulate, putamen, insula, amygdala, cerebellum and the extrastriatal-visual cortex exhibited activation; with tic-onset, the thalamus, central operculum, primary motor and somatosensory cortices exhibited activation. Analysis of resting state data resulted in 21 components including the so-called default-mode network. Network strength in those regions in SMA of two premotor ICA maps that were also active prior to tic occurrence, correlated significantly with disease severity according to the Yale Global Tic Severity Scale (YGTTS) scores. DISCUSSION: We demonstrate that the temporal pattern of tic generation follows the cortico-striato-thalamo-cortical circuit, and that cortical structures precede subcortical activation. The analysis of spontaneous fluctuations highlights the role of cortical premotor structures. Our study corroborates the notion of TS as a network disorder in which abnormal RSN activity might contribute to the generation of tics in SMA. [less ▲]

Detailed reference viewed: 22 (0 ULg)
Full Text
Peer Reviewed
See detailImaging-guided percutaneous spinal biopsy
Stulko, J.; Miezentseva, V. A.; Gerard, L. et al

in Revue Médicale de Liège (2013), 68(3), 128-33

The aim of this article is to present the value and limitations of image-guided percutaneous biopsy in spinal disorders. The indications and contraindications of percutaneous spinal biopsy and the ... [more ▼]

The aim of this article is to present the value and limitations of image-guided percutaneous biopsy in spinal disorders. The indications and contraindications of percutaneous spinal biopsy and the different techniques and materials used are discussed. The decision for this type of biopsy and the choice of technique should be made by a multidisciplinary team. Percutaneous spinal biopsy is a safe, inexpensive and possible as an outpatient. The effectiveness of percutaneous spinal biopsy is around 70%. [less ▲]

Detailed reference viewed: 10 (2 ULg)