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See detailNonimaging achromatic shaped Fresnel lenses for ultrahigh solar concentration
Languy, Fabian ULg; Habraken, Serge ULg

in Optics Letters (2013), 38(10), 1730-1732

The maximum concentration ratio achievable with a solar concentrator made of a single refractive primary optics is much more limited by the chromatic aberration than by any other aberration. Therefore ... [more ▼]

The maximum concentration ratio achievable with a solar concentrator made of a single refractive primary optics is much more limited by the chromatic aberration than by any other aberration. Therefore achromatic doublets made with poly(methyl methacrylate) and polycarbonate are of great interest to enhance the concentration ratio and to achieve a spectrally uniform flux on the receiver. In this Letter, shaped achromatic Fresnel lenses are investigated. One lossless design is of high interest since it provides spectrally and spatially uniform flux without being affected by soiling problems. With this design an optical concentration ratio of about 8500× can be achieved. [less ▲]

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See detailNoninfectious dermatoses of pregnancy
QUATRESOOZ, Pascale ULg; PIERARD-FRANCHIMONT, Claudine ULg; PIERARD, Gérald ULg

in Therapeutique dermatologique (2007)

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See detailNoninvasive assessment of Crohn's disease intestinal lesions with F-18-FDG PET/CT
Louis, Edouard ULg; Ancion, Geoffrey; Colard, Arnaud et al

in Journal of Nuclear Medicine (2007), 48(7), 1053-1059

Pilot studies have shown good sensitivity and specificity for F-18-FDG PET in detecting gastrointestinal lesions of Crohn's disease. The combination of F-18-FDG PET with CT may further improve the ... [more ▼]

Pilot studies have shown good sensitivity and specificity for F-18-FDG PET in detecting gastrointestinal lesions of Crohn's disease. The combination of F-18-FDG PET with CT may further improve the localization and characterization of lesions with increased F-18-FDG uptake. Our aim was to assess the use of F-18-FDG PET/CT in evaluating the activity and location of Crohn's disease along the gastrointestinal tract. Methods: After giving informed consent, 22 patients with Crohn's disease were prospectively studied. They underwent F-18-FDG PET/CT, followed by ileocolonoscopy within 1 wk (mean, 2 d). The Crohn's disease activity index (CDAI) was calculated, and serum C-reactive protein (CRP) and fecal calprotectin were measured before endoscopy. The Crohn's disease endoscopy index of severity (CDEIS) was calculated during endoscopy. The global CDEIS score and endoscopic subscores for various ileocolonic segments were used for analysis. Results: Globally, 95 intestinal and colonic segments in 22 patients were analyzed. F-18-FDG PET/CT detected 35 of 48 endoscopically affected segments (sensitivity for the detection of endoscopic lesions, 72.9%). The sensitivity of F-18-FDG PET/CT for the detection of severe endoscopic lesions (deep ulcers and strictures) was 100% (14/14). The global PET/CT score significantly correlated with CDEIS (r = 0.51; 95% confidence interval [Cl], 0.09-0.77; P = 0.017), CDAI (r = 0.58; 95% Cl, 0.17-0.80; P = 0.005), and CRP (r = 0.56; 95% Cl, 0.19-0.81; P = 0.007). Conclusion: F-18-FDG PET/CT was globally well correlated to the clinical, endoscopic, and biologic activity of Crohn's disease. Above all, this technique had a good sensitivity for the detection of intestinal and colonic segments with moderate to severe mucosal lesions. The potential impact of this promising tool on the global management of patients with Crohn's disease should be further evaluated in prospective studies. [less ▲]

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See detailNoninvasive detection of tumor hypoxia using the 2-nitroimidazole [18F]EF1.
Evans, S. M.; Kachur, A. V.; Shiue, C. Y. et al

in Journal of Nuclear Medicine : Official Publication, Society of Nuclear Medicine (2000), 41(2), 327-36

The noninvasive assessment of tumor hypoxia in vivo is under active investigation because hypoxia has been shown to be an important prognostic factor for therapy resistance. Various nuclear medicine ... [more ▼]

The noninvasive assessment of tumor hypoxia in vivo is under active investigation because hypoxia has been shown to be an important prognostic factor for therapy resistance. Various nuclear medicine imaging modalities are being used, including PET imaging of 18F-containing compounds. In this study, we report the development of 18F-labeled EF1 for noninvasive imaging of hypoxia. EF1 is a 3-monofluoro analog of the well-characterized hypoxia marker EF5, 2(2-nitro-1H-imidazol-1-yl)-N-(2,2,3,3,3-pentafluoropropyl)acetami de, which has been used to detect hypoxia in tumor and nontumor systems using immunohistochemical methods. METHODS: We have studied 2 rat tumor types: the hypoxic Morris 7777 (Q7) hepatoma and the oxic 9LF glioma tumor, each grown in subcutaneous sites. PET studies were performed using a pharmacological dose of nonradioactive carrier in addition to [18F]EF1 to optimize and assess drug biodistribution. After PET imaging of the tumor-bearing rats, tissues were obtained for gamma-counting of the 18F in various tissues and immunohistochemical detection of intracellular drug adducts in tumors. In one pair of tumors, Eppendorf needle electrode studies were performed. RESULTS: [18F]EF1 was excreted dominantly through the urinary tract. The tumor-to-muscle (T/M) ratio of [18F]EF1 in the Q7 tumors was 2.7 and 2.4 based on PET studies and 2.1, 2.5, and 3.0 based on gamma-counting of the tissues (n = 3). In contrast, the T/M ratio of [18F]EF1 in the 9LF glioma tumor was 0.8 and 0.5 based on PET studies and 1.0, 1.2, and 1.4 based on gamma-counting of the tissues (n = 3). Immunohistochemical analysis of drug adducts for the two tumor types agreed with the radioactivity analysis. In the Q7 tumor, substantial heterogeneous binding was observed throughout the tumor, whereas in the 9LF tumor minimal binding was found. CONCLUSION: [18F]EF1 is an excellent radiotracer for noninvasive imaging of tumor hypoxia. [less ▲]

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See detailNonisotopic substrate for assaying both human zinc and NAD+-dependent histone deacetylases.
Heltweg, Birgit; Dequiedt, Franck ULg; Verdin, Eric et al

in Analytical Biochemistry (2003), 319(1), 42-8

Histone deacetylases (HDACs) are involved in the regulation of transcription and their inhibitors are a promising class of new anticancer drugs. We have previously reported Boc(Ac)Lys-AMC, also termed MAL ... [more ▼]

Histone deacetylases (HDACs) are involved in the regulation of transcription and their inhibitors are a promising class of new anticancer drugs. We have previously reported Boc(Ac)Lys-AMC, also termed MAL, as a fluorescent substrate for HDACs. Now we present a modification of MAL called Z-MAL that is characterized by an increased rate of conversion by histone deacetylases of classes I and II and the recently discovered sirtuins (histone deacetylases class III). MAL and Z-MAL are the first nonradioactive substrates for class III enzymes. The new substrate Z-MAL allows for shorter assay times in inhibitor screening and is applicable to diverse sources of deacetylase activity even with completely different catalytic mechanisms. Interestingly, MAL shows some relative preference toward class II, indicating that subtype selectivity in small-molecule HDAC substrates might be obtained. [less ▲]

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See detailNonlésional central lobule seizures : use of awake cortical mapping and subdural grid monitoring for resection of seizure focus
Collignon, F.; Cohen-Gadol, A.; Meyer, F. et al

Conference (2006, March)

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See detailNonlinear Aeroelastic Research at the Dynamics and Aeroelasticity Research Group
Dimitriadis, Grigorios ULg

Conference (2003, June)

This work is a presentation of the recent research in nonlinearity carried out at the Dynamics and Aeroelasticity Research Group (DARG) of the University of Manchester, School of Engineering

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See detailNonlinear Aeroelastic vibrations and galloping of iced conductor lines under wind.
Shklyarchuk, Fedor; Danilin, Alexander; Lilien, Jean-Louis ULg et al

in Proceedings of the 7th International Conference on Cable Dynamics (2007, December)

galloping model for one span single conductor dead ended.

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See detailNonlinear analysis of cardiac rythm fluctuations using DFA method
Absil, P.-A.; Sepulchre, Rodolphe ULg; Bilge, A. et al

in Physica A: Statistical Mechanics and its Applications (1999), 272

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See detailNonlinear compressibility effects in fluid-structure interaction and their implications on the air-blast loading of structures
Kambouchev, Nayden; Noels, Ludovic ULg; Radovitzky, Raúl

in Journal of Applied Physics (2006), 100(6), 063519

The impulse imparted by a blast wave to a freestanding solid plate is studied analytically and numerically focusing on the case in which nonlinear compressibility effects in the fluid are important, as is ... [more ▼]

The impulse imparted by a blast wave to a freestanding solid plate is studied analytically and numerically focusing on the case in which nonlinear compressibility effects in the fluid are important, as is the case for explosions in air. The analysis furnishes, in effect, an extension of Taylor's pioneering contribution to the understanding of the influence of fluid-structure interaction (FSI) on the blast loading of structures [The Scientific Papers of Sir Geoffrey Ingram Taylor, edited by G. K. Batchelor (Cambridge University Press, Cambridge, 1963), Vol. III, pp. 287-303] to the nonlinear range. The limiting cases of extremely heavy and extremely light plates are explored analytically for arbitrary blast intensity, from where it is concluded that a modified nondimensional parameter representing the mass of compressed fluid relative to the mass of the plate governs the FSI. The intermediate asymptotic FSI regime is studied using a numerical method based on a Lagrangian formulation of the Euler equations of compressible flow and conventional shock-capturing techniques. Based on the analytical and numerical results, an approximate formula describing the entire range of relevant FSI conditions is proposed. The main conclusion of this work is that nonlinear fluid compressibility further enhances the beneficial effects of FSI in reducing the impulse transmitted to the structure. More specifically, it is found that transmitted impulse reductions due to FSI when compared to those obtained ignoring FSI effects are more significant than in the acoustic limit. This result can be advantageously exploited in the design and optimization of structures with increased blast resistance. (c) 2006 American Institute of Physics. [less ▲]

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See detailNonlinear Computational Homogenization Method for the Evaluation of Eddy Currents in Soft Magnetic Composites
Niyonzima, Innocent ULg; Sabariego, Ruth Vazquez; Dular, Patrick ULg et al

in Proceedings of the 19th Conference on the Computation of Electromagnetic Fields (COMPUMAG2013) (2013, July)

In this paper, a heterogeneous multiscale method (HMM) technique is applied to model the behaviour of electromagnetic fields in soft magnetic composites (SMC). Two problems are derived from the two-scale ... [more ▼]

In this paper, a heterogeneous multiscale method (HMM) technique is applied to model the behaviour of electromagnetic fields in soft magnetic composites (SMC). Two problems are derived from the two-scale homogenization theory: a macroscale problem that captures the slow variations of the overall solution, and many mesoscale problems that allow determining the constitutive laws at the macroscale. As application, an SMC core is considered. [less ▲]

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See detailNonlinear Computational Homogenization Method for the Evaluation of Eddy Currents in Soft Magnetic Composites
Niyonzima, Innocent ULg; Sabariego, Ruth Vazquez; Dular, Patrick ULg et al

in IEEE Transactions on Magnetics (2014), 50(02),

In this paper, a heterogeneous multiscale method technique is applied to model the behavior of electromagnetic fields in soft magnetic composites (SMC). Two problems are derived from the two-scale ... [more ▼]

In this paper, a heterogeneous multiscale method technique is applied to model the behavior of electromagnetic fields in soft magnetic composites (SMC). Two problems are derived from the two-scale homogenization theory: a macroscale problem that captures the slow variations of the overall solution, and many mesoscale problems that allow determining the constitutive laws at the macroscale. As application, an SMC core is considered. [less ▲]

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See detailNonlinear Drillstring Dynamics Analysis
Germay, Christophe; deWouw, Nathan Van; Nijmeijer, Henk et al

in SIAM Journal on Applied Dynamical Systems (2009), 8(2), 527--553

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See detailNonlinear Dynamic Analysis of Aerospace Structures
Kerschen, Gaëtan ULg; Noël, Jean-Philippe ULg; Renson, Ludovic ULg et al

Conference (2012, October)

Current practice in industry is to rely on linear finite element simulations. However, nonlinearity is a frequent occurrence in engineering structures. It is at the origin of rich and complex dynamical ... [more ▼]

Current practice in industry is to rely on linear finite element simulations. However, nonlinearity is a frequent occurrence in engineering structures. It is at the origin of rich and complex dynamical phenomena that cannot be observed in linear structures. Solving both the direct and inverse problems in nonlinear structural dynamics therefore warrants the development of appropriate methodologies. The focus of the presentation will first be on the inverse problem. We will describe the different steps of the nonlinear system identification process and discuss the current capabilities of existing methods. The presentation will then address the direct problem during which the identified model is used for accurately predicting the structure’s dynamic characteristics. A rigorous nonlinear extension of modal analysis will be presented, and we will show that it represents a very useful framework for understanding nonlinear dynamical phenomena and supporting design decisions. Two real-life aerospace structures will be considered for illustrating the proposed developments. [less ▲]

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See detailNonlinear dynamic analysis of an F-16 aircraft using GVT data
Noël, Jean-Philippe ULg; Renson, Ludovic ULg; Kerschen, Gaëtan ULg et al

in Proceedings of the International Forum on Aeroelasticity and Structural Dynamics (2013, June)

This paper aims at investigating the nonlinear dynamics of an F-16 aircraft, based upon sine-sweep data collected during a ground vibration test (GVT) campaign. Various analysis techniques, including the ... [more ▼]

This paper aims at investigating the nonlinear dynamics of an F-16 aircraft, based upon sine-sweep data collected during a ground vibration test (GVT) campaign. Various analysis techniques, including the mere visual inspection of the time series, the wavelet transform and the restoring force surface method, are utilised and reveal that the F-16 wing-to-payload mounting interfaces exhibit both softening and hardening nonlinearities. [less ▲]

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See detailNonlinear Dynamics and Control of Deep Drilling Systems
Detournay, Emmanuel; Denoël, Vincent ULg; van de Wouw, Nathan

Book published by College of Science and Engineering (2014)

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See detailNonlinear Dynamics Of A Drill Bit Under Percussive Activation
Depouhon, Alexandre ULg; Denoël, Vincent ULg; Detournay, Emmanuel

in Proceedings of ICTAM 2012, Beijing (2012, August)

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See detailNonlinear electromagnetic modes in astrophysical plasmas with dust distributions
Verheest, F.; Cattaert, Tom ULg

in Astronomy and Astrophysics (2004), 421(1), 17-21

A derivative nonlinear Schrodinger equation is obtained for parallel electromagnetic modes in plasmas containing polydisperse charged dust. The coefficient of the dispersive term in that equation is ... [more ▼]

A derivative nonlinear Schrodinger equation is obtained for parallel electromagnetic modes in plasmas containing polydisperse charged dust. The coefficient of the dispersive term in that equation is dominated by the dust rather than the (plasma) ions, and polydisperse dust yields a larger coefficient in absolute value than an equivalent monodisperse description. This leads to a significant broadening of the nonlinear structure due to the presence of polydisperse rather than monodisperse dust, the latter contributing in itself already to a substantial increase in the width of envelope solitons compared to dust-free plasmas. When modelling the charged dust by a power-law distribution occurring in planetary ring and other astrophysical systems, it depends very much on the power-law index whether the smaller or the larger grains are more important. For certain indices the more numerous smaller grains determine the charge and mass densities, but the larger dust dominates the linear and nonlinear dispersive effects. [less ▲]

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See detailNonlinear energy pumpin: A new paradigm for vibration isolation
Vakakis, Alexander F.; McFArland, D. Michael; Kerschen, Gaëtan ULg et al

in 3rd China-Japan US Symposium on Health Mondial and Control of Structures, Dalian, 2004 (2004)

We discuss passive nonlinear energy pumping from a linear (main) mechanical structure to a weakly coupled, local, passive nonlinear energy sink (NES). We show that the NES can be designed to effectively ... [more ▼]

We discuss passive nonlinear energy pumping from a linear (main) mechanical structure to a weakly coupled, local, passive nonlinear energy sink (NES). We show that the NES can be designed to effectively absorb vibrational energy from the main structure in a one-way, irreversible fashion. We demonstrate the occurrence of pumping cascades, where an appropriately designed NES passively extracts energy sequentially from a number of modes of the main (linear) structure, interacting individually with each mode before moving to the next. Experimental results confirm our theoretical findings. The applications of the nonlinear energy pumping phenomenon to the problem of vibration and shock isolation will be discussed. [less ▲]

Detailed reference viewed: 26 (1 ULg)