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See detailFIRST, a fibered aperture masking instrument: Results of the Lick observing campaign
Bordwell, Baylee; Duchene, Gaspard; Huby, Elsa ULg et al

Poster (2015, January 01)

FIRST is a prototype instrument aimed at achieving high dynamic range and angular resolution in ground-based images at visible wavelengths near the diffraction limit. FIRST utilizes an aperture masking ... [more ▼]

FIRST is a prototype instrument aimed at achieving high dynamic range and angular resolution in ground-based images at visible wavelengths near the diffraction limit. FIRST utilizes an aperture masking-like technique that makes use of single-mode fibers and pupil remapping to maximize the area of the telescope mirror in use. While located at Lick observatory in 2011 and 2012, FIRST observed 25 binary systems with the Shane 3m telescope, with separations ranging from 20 to 200 mas, comparable to the 50 mas diffraction limit for our central wavelength. Huby et al. (2013) has reported results for the Capella system that established the utility of FIRST for characterizing stellar binaries using the directly measured spectral flux ratio. Using an improved data analysis pipeline, we obtained closure phase measurements for a majority of the targets observed at Lick, and derived angular separations and spectral flux ratios. From the spectral flux ratios we obtained spectra for the companions over at least 600-850 nm with R~300. Finally, by obtaining results for many binary systems we have better constrained the current performance of FIRST, which has an exciting future ahead at its current location behind SCExAO at the Subaru 8.2 m telescope, where it will eventually become available for general use by the astronomical community. [less ▲]

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See detailFIRST, a high dynamic range imager, mounted on the 3-m Shane Telescope
Huby, Elsa ULg

Scientific conference (2012, April)

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See detailFIRST, Fibered Imager foR a Single Telescope
Huby, Elsa ULg

Conference (2013, February)

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See detailFirst- and multi-swing transient stability limits of the Hydro-Québec system using the SIME method
Zhang, Y.; Wehenkel, Louis ULg; Rousseaux, Patricia ULg et al

in Proceedings of the Melecon'96 Conference (1996)

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See detailFirst- and second-order Fermi acceleration in thick relativistic shocks
Meli, Athina ULg

in AIP Conference Proceedings (2012)

Shocks in relativistic jets are regions where cosmic ray acceleration takes place mainly via two kinds of Fermi acceleration mechanism: The first-order and the second-order Fermi acceleration. Moreover ... [more ▼]

Shocks in relativistic jets are regions where cosmic ray acceleration takes place mainly via two kinds of Fermi acceleration mechanism: The first-order and the second-order Fermi acceleration. Moreover, the back-reaction of accelerated particles in astrophysical shock fronts leads to the formation of a precursor (thick) shock with a length scale which can correspond to the diffusive scale of the energetic particles. Our scope here is to investigate the properties of particle shock acceleration, using test-particle simulation studies, assuming stochastic and diffusive acceleration mechanisms, in thick parallel and perpendicular relativistic shocks. The role of the above parameters in the acceleration efficiency and generated cosmic ray spectra, is important to understanding further the favourable subject of the cosmic ray shock acceleration in relativistic astrophysical environments. [less ▲]

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See detailFirst-choice treatment for post menopausal osteoporotic patients
Reginster, Jean-Yves ULg

in Osteoporosis International (2007, March), 18(Suppl.1), 178

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See detailFirst-generation versus third generation comprehensive geriatric assessment instruments in the acute hospital setting: a comparison of the Minimum Geriatric Screening Tools (MGST) and the interRAI Acute Care (interRAIAC)
WELLENS, N. L.; DESCHODT, M.; FLAMAING, J. et al

in Journal of Nutrition, Health & Aging (The) (2011), 15(8), 638-644

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See detailFirst-light LBT Nulling Interferometric Observations: Warm Exozodiacal Dust Resolved within a Few AU of eta Crv
Defrere, Denis ULg; Hinz, P. M.; Skemer, A. J. et al

in Astrophysical Journal (2015), 799

We report on the first nulling interferometric observations with the Large Binocular Telescope Interferometer (LBTI), resolving the N' band (9.81-12.41 μm) emission around the nearby main-sequence star η ... [more ▼]

We report on the first nulling interferometric observations with the Large Binocular Telescope Interferometer (LBTI), resolving the N' band (9.81-12.41 μm) emission around the nearby main-sequence star η Crv (F2V, 1-2 Gyr). The measured source null depth amounts to 4.40% ± 0.35% over a field-of-view of 140 mas in radius (~2.6 AU for the distance of η Crv) and shows no significant variation over 35° of sky rotation. This relatively low null is unexpected given the total disk to star flux ratio measured by the Spitzer Infrared Spectrograph (IRS; ~23% across the N' band), suggesting that a significant fraction of the dust lies within the central nulled response of the LBTI (79 mas or 1.4 AU). Modeling of the warm disk shows that it cannot resemble a scaled version of the solar zodiacal cloud unless it is almost perpendicular to the outer disk imaged by Herschel. It is more likely that the inner and outer disks are coplanar and the warm dust is located at a distance of 0.5-1.0 AU, significantly closer than previously predicted by models of the IRS spectrum (~3 AU). The predicted disk sizes can be reconciled if the warm disk is not centrosymmetric, or if the dust particles are dominated by very small grains. Both possibilities hint that a recent collision has produced much of the dust. Finally, we discuss the implications for the presence of dust for the distance where the insolation is the same as Earth's (2.3 AU). [less ▲]

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See detailFirst-line crizotinib versus chemotherapy in ALK-positive lung cancer.
Solomon, Benjamin J.; Mok, Tony; Kim, Dong-Wan et al

in The New England journal of medicine (2014), 371(23), 2167-77

BACKGROUND: The efficacy of the ALK inhibitor crizotinib as compared with standard chemotherapy as first-line treatment for advanced ALK-positive non-small-cell lung cancer (NSCLC) is unknown. METHODS: We ... [more ▼]

BACKGROUND: The efficacy of the ALK inhibitor crizotinib as compared with standard chemotherapy as first-line treatment for advanced ALK-positive non-small-cell lung cancer (NSCLC) is unknown. METHODS: We conducted an open-label, phase 3 trial comparing crizotinib with chemotherapy in 343 patients with advanced ALK-positive nonsquamous NSCLC who had received no previous systemic treatment for advanced disease. Patients were randomly assigned to receive oral crizotinib at a dose of 250 mg twice daily or to receive intravenous chemotherapy (pemetrexed, 500 mg per square meter of body-surface area, plus either cisplatin, 75 mg per square meter, or carboplatin, target area under the curve of 5 to 6 mg per milliliter per minute) every 3 weeks for up to six cycles. Crossover to crizotinib treatment after disease progression was permitted for patients receiving chemotherapy. The primary end point was progression-free survival as assessed by independent radiologic review. RESULTS: Progression-free survival was significantly longer with crizotinib than with chemotherapy (median, 10.9 months vs. 7.0 months; hazard ratio for progression or death with crizotinib, 0.45; 95% confidence interval [CI], 0.35 to 0.60; P<0.001). Objective response rates were 74% and 45%, respectively (P<0.001). Median overall survival was not reached in either group (hazard ratio for death with crizotinib, 0.82; 95% CI, 0.54 to 1.26; P=0.36); the probability of 1-year survival was 84% with crizotinib and 79% with chemotherapy. The most common adverse events with crizotinib were vision disorders, diarrhea, nausea, and edema, and the most common events with chemotherapy were nausea, fatigue, vomiting, and decreased appetite. As compared with chemotherapy, crizotinib was associated with greater reduction in lung cancer symptoms and greater improvement in quality of life. CONCLUSIONS: Crizotinib was superior to standard first-line pemetrexed-plus-platinum chemotherapy in patients with previously untreated advanced ALK-positive NSCLC. (Funded by Pfizer; PROFILE 1014 ClinicalTrials.gov number, NCT01154140.). [less ▲]

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See detailA first-order energy-dissipative momentum-conserving scheme for elasto-plasticity using the variational updates formulation
Noels, Ludovic ULg; Stainier, Laurent ULg; Ponthot, Jean-Philippe ULg

in Computer Methods in Applied Mechanics & Engineering (2008), 197(6-8), 706726

In a previous paper [L. Noels, L. Stainier, J.-P. Ponthot, An energy momentum conserving algorithm using the variational formulation of visco-plastic updates, Int. J. Numer. Methods Engrg. 65 (2006) 904 ... [more ▼]

In a previous paper [L. Noels, L. Stainier, J.-P. Ponthot, An energy momentum conserving algorithm using the variational formulation of visco-plastic updates, Int. J. Numer. Methods Engrg. 65 (2006) 904-942] the authors demonstrated the efficiency of the variational formulation of elasto-plastic updates to develop energy-momentum conserving time integration algorithms. Indeed, within such a framework, the stress tensor always derives from an incremental potential, even when plastic behavior is considered. Therefore the verification of the conservation of energy in the non-linear range can easily be demonstrated: the sum of the reversible stored energy and irreversible dissipated energy exactly corresponds to the work of the external forces applied to the structure. Although this formulation was shown to be accurate and robust, the introduction of numerical dissipation for high-frequency numerical modes can be necessary to simulate complex phenomena. In this work, we propose a modification of the variational updates framework to introduce this numerical property, leading to a new energy-dissipative momentum-conserving time-integration algorithm for elasto-plasticity. (c) 2007 Elsevier B.V. All rights reserved. [less ▲]

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See detailFirst-principle study of crystals exhibiting an incommensurate phase transition
Gonze, X.; Caracas, R.; Sonnet, R. et al

in AIP Conference Proceedings (2000), 535

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See detailFirst-principles and experimental studies of hexagonal YMnO3 single crystals and epitaxial films
Prikockyte, Alina ULg

Doctoral thesis (2012)

Multiferroic materials have attracted much interest during the recent years. Our study is devoted to a prototypic system: yttrium manganite. In particular, we focus on the ferroelectric properties in bulk ... [more ▼]

Multiferroic materials have attracted much interest during the recent years. Our study is devoted to a prototypic system: yttrium manganite. In particular, we focus on the ferroelectric properties in bulk and in thin film forms. Yttrium manganite belongs to the class of ABO3 compounds. Most theoretical studies of ferroelectricity to date were concentrated on cubic perovskite ABO3. Yttrium manganite is hexagonal and is an improper ferroelectric. We were interested to study theoretically and experimentally how these two features behave in thin film form. Our study is organized as follows. [less ▲]

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See detailFirst-principles calculation of kinetic barriers and metastability for the corundum-to-Rh/sub 2/O/sub 3/(II) transition in Al/sub 2/O/sub 3/
Xu, Bin ULg; Stokes, Harold; Dong, Jianjun

in Journal of Physics : Condensed Matter (2010), 22(31), 3154036-3154036

We demonstrate that the rhombohedral corundum crystal and the orthorhombic Rh/sub 2/O/sub 3/ (II) crystal are structurally related by a diffusionless monoclinic common subgroup pathway, along which the ... [more ▼]

We demonstrate that the rhombohedral corundum crystal and the orthorhombic Rh/sub 2/O/sub 3/ (II) crystal are structurally related by a diffusionless monoclinic common subgroup pathway, along which the intermediate structures have the space group P2/c symmetry. This transformation pathway is energetically favored because the majority of Al-O bonds are preserved during the transition. Only 1/3 of the four-coordinated anions and 1/2 of the six-coordinated cations break and reform a single bond. No other bonds are broken in the transformation. Our calculated forward (corundum-to-Rh/sub 2/O/sub 3/ (II)) enthalpy barrier (about 140 meV/atom) in Al/sub 2/O/sub 3/ is not pressure-sensitive at least up to 160 GPa, which is consistent with the observed metastability of the corundum phase around room temperature. In contrast, we predict a significantly decreasing backward (Rh/sub 2/O/sub 3/ (II)-to-corundum) enthalpy barrier on decompression, which suggests that the high-pressure Rh/sub 2/O/sub 3/ (II) phase of Al/sub 2/O/sub 3/ is unlikely to be recoverable at ambient conditions. In addition, we propose a general, common subgroup-based approach to compare elastic properties of two phases with different Bravais lattices. By treating both rhombohedral and orthorhombic phases with common monoclinic P2/c unit cells (non-primitive for the corundum phase), we show that the elastic properties of the high-pressure Rh/sub 2/O/sub 3/ (II) phase are very comparable to those of the ambient corundum phase. [less ▲]

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See detailFirst-principles calculation of the band offset at BaO/BaTiO3 and SrO/SrTiO3 interfaces
Junquera, J.; Zimmer, M.; Ordejon, P. et al

in Physical Review. B, Condensed Matter and Materials Physics (2003), 67

We report first-principles density-functional pseudopotential calculations on the atomic structures, electronic properties, and band offsets of BaO/BaTiO3 and SrO/SrTiO3 nanosized heterojunctions grown on ... [more ▼]

We report first-principles density-functional pseudopotential calculations on the atomic structures, electronic properties, and band offsets of BaO/BaTiO3 and SrO/SrTiO3 nanosized heterojunctions grown on top of a silicon substrate. The density of states at the junction does not reveal any electronic induced interface states. A dominant perovskite character is found at the interface layer. The tunability of the band offset with the strain conditions imposed by the substrate is studied. Using previously reported theoretical data available for Si/SrO, Si/BaO, SrTiO3/Pt, and BaTiO3/SrRuO3 interfaces we extrapolate the band alignments along two gate stacks of technological interest: Si/SrO/SrTiO3/Pt and Si/BaO/BaTiO3/SrRuO3 heterostructures. [less ▲]

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See detailFirst-principles calculation of the electronic, dielectric, and dynamical properties of CaF2
Verstraete, Matthieu ULg; Gonze, Xavier

in Physical Review. B : Condensed Matter (2003), 68

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See detailFirst-principles calculations of dielectric and effective charge tensors in Barium Titanate
Ghosez, Philippe ULg; Gonze, X.; Michenaud, J. P.

in Ferroelectrics (1994), 153

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See detailFirst-principles calculations of the nonlinear optical susceptibilities and Raman scattering spectra of lithium niobate
Hermet, P.; Veithen, M.; Ghosez, Philippe ULg

in Journal of Physics : Condensed Matter (2007), 19

Nonlinear optical susceptibilities and nonresonant Raman scattering spectra of the ferroelectric phase of lithium niobate (LiNbO3) are computed using a first-principles approach based on density ... [more ▼]

Nonlinear optical susceptibilities and nonresonant Raman scattering spectra of the ferroelectric phase of lithium niobate (LiNbO3) are computed using a first-principles approach based on density functional theory and taking advantage of a recent implementation based on the nonlinear response formalism and the 2n+1 theorem. Infrared reflectivity spectra of the ferroelectric phase of LiNbO3 are also calculated. New assignments are proposed for the E-modes, clarifying a longstanding debate in the literature. In addition, it is shown that knowledge of the nonlinear optical susceptibility tensor of LiNbO3 does not significantly alter the profile of its Raman spectra in a configuration where the longitudinal optic modes are involved. [less ▲]

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See detailFirst-principles calculations of the structural and dynamical properties of ferroelectric YMnO3
Prikockyte, Alina ULg; Bilc, Daniel ULg; Hermet, Patrick ULg et al

in Physical Review. B, Condensed Matter and Materials Physics (2011), 84

We report the structural and dynamical properties of the ground state ferroelectricP63cm structure of hexagonal YMnO3. The lattice parameters, atomic positions, local magnetic moment of Mn atoms, band gap ... [more ▼]

We report the structural and dynamical properties of the ground state ferroelectricP63cm structure of hexagonal YMnO3. The lattice parameters, atomic positions, local magnetic moment of Mn atoms, band gap, and -point phonons are calculated within the local spin-density approximation plus Hubbard U term and the B1-WC hybrid functional. Our results are discussed in comparison to theoretical and experimental values available in the literature. Based on our first-principles calculations, we propose a reassignment of certain modes. We also discuss the relation between the phonon modes of the ferroelectric P63cm phase and those of the paraelectric P63/mmc phase that condense at the phase transition. [less ▲]

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