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See detailLine narrowing effect on the retrieval of HF and HCl vertical profiles from ground-based FTIR measurements
Barret, Brice; Hurtmans, Daniel; Carleer, Michel R. et al

in Journal of Quantitative Spectroscopy & Radiative Transfer (2005), 95(4), 499-519

Collision-induced line narrowing, which has been discovered in the 1950s and investigated thoroughly in the laboratory since then, has yet never been taken into account in the spectroscopic remote sensing ... [more ▼]

Collision-induced line narrowing, which has been discovered in the 1950s and investigated thoroughly in the laboratory since then, has yet never been taken into account in the spectroscopic remote sensing of the atmosphere. This work investigates the effect of collision-induced line narrowing onto the retrieval of HCl and HF vertical profiles from ground-based solar absorption FTIR measurements made at the NDSC station of the Jungfraujoch (46.5 degrees N, 8 degrees E and 3580 m above see level). The retrievals are performed with the Atmosphit software, recently developed at the Universite Libre de Bruxelles. It is presented in this paper for the first time and is validated against the widely used SFIT2 software. The impact of the line narrowing onto the retrieval of HCl and HF vertical profiles is examined relying on careful information content and error budget analyses. We report that the effect is relatively weak for HCl but significant for HF. Confirmation of the need to take the line narrowing into account for the retrieval of vertical profiles from ground-based FTIR spectra is given by comparison with data from the HALOE space borne instrument, rather insensitive to this spectroscopic effect. (c) 2005 Elsevier Ltd. All rights reserved. [less ▲]

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See detailLine profile variability in the massive binary HD 152219
Sana, H.; Gosset, Eric ULg

in Communication in Asteroseismology (2009, July 01), 158

HD 152219 is a massive binary system with O9.5 III and B1-2 III/V components and a short orbital period of 4.2 d. In a previous work, we showed that the primary star (M_{prim}˜21 M_&sun;) was presenting ... [more ▼]

HD 152219 is a massive binary system with O9.5 III and B1-2 III/V components and a short orbital period of 4.2 d. In a previous work, we showed that the primary star (M_{prim}˜21 M_&sun;) was presenting clear line profile variabilities (LPVs) that might be caused by nonradial pulsations (NRPs). In the present work, we report on an intensive spectroscopic monitoring, that aimed at unveiling the nature of the detected LPVs. Based on this new data set, we discard the NRPs and point out the Rossiter-McLaughlin effect as % being the cause of the observed LPVs. The upper limit derived on the amplitude of undetected NRPs, if any, is set at a couple of part per thousands of the continuum level. [less ▲]

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See detailLine profile variability in the spectra of Oef stars - II. HD192281, HD14442 and HD14434
De Becker, Michaël ULg; Rauw, Grégor ULg

in Astronomy and Astrophysics (2004), 427(3), 995-1008

We present the very first analysis of the spectroscopic variability of the three rapidly rotating Oef stars HD 192281 (O5(ef)), HD14442 (O5.5ef) and HD 14434 (O6.5( ef)). Radial velocities of the He II ... [more ▼]

We present the very first analysis of the spectroscopic variability of the three rapidly rotating Oef stars HD 192281 (O5(ef)), HD14442 (O5.5ef) and HD 14434 (O6.5( ef)). Radial velocities of the He II lambda 4541 line reveal no evidence of binarity on time scales of a few days, or from one year to the next, for any of the targets. The He II lambda 4686 double-peaked emission and, to some extent, the H absorption line display significant profile variability in the spectra of all three stars. Data gathered during different observing runs spread over six years reveal a rather stable time scale for HD 192281 and HD14442, whereas the variability pattern changes significantly from one year to the other. The case of HD 14434 is less clear as no obvious time scale emerges from our analysis. In a tentative way to interpret this variability, stellar rotation remains a possible clock for HD 192281 and HD14442. However, currently available models addressing stellar rotation fail to explain some crucial aspects of the observed variability behaviour, which appear to be even more complex in the case of HD 14434. [less ▲]

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See detailLine profile variability in the spectra of Oef stars. I. BD + 60deg 2522
Rauw, Grégor ULg; De Becker, Michaël ULg; Vreux, Jean-Marie ULg

in Astronomy and Astrophysics (2003), 399

We report the analysis of a long term observing campaign designed to monitor the spectroscopic variability of the Oef star BD +60deg 2522. We find that the double-peaked He {II} lambda 4686 emission line ... [more ▼]

We report the analysis of a long term observing campaign designed to monitor the spectroscopic variability of the Oef star BD +60deg 2522. We find that the double-peaked He {II} lambda 4686 emission line undergoes strong profile variability on time scales of 2-3 day. However, the time scale as well as the pattern of these variations turn out to be epoch dependent and the phenomenon is thus most likely not ruled by a single stable clock. On the other hand, the absorption lines in the spectrum of BD +60deg 2522 display line profile variability on time scales of a few hours that might be related to non-radial pulsations. We tentatively propose that the beating of several non-radial pulsation modes triggers transient large-scale density perturbations in a confined stellar wind that produce the 2-3 day time scale variability. [less ▲]

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See detailLine profile variability in the spectrum of the O(f) supergiant HD 192639
Rauw, Grégor ULg; Vreux, Jean-Marie ULg

in Astronomy and Astrophysics (1998), 335

We report the results of a medium-resolution spectroscopic investigation of the O(f) supergiant HD 192639. Particular attention is paid to the He {ii}\ lambda 4686 line. This line displays strong profile ... [more ▼]

We report the results of a medium-resolution spectroscopic investigation of the O(f) supergiant HD 192639. Particular attention is paid to the He {ii}\ lambda 4686 line. This line displays strong profile variability on time scales of a few days, changing from a P-Cygni profile with a double-peaked emission component to a pure blue-shifted emission line. It appears that the variability of most of the absorption lines present in our spectra is correlated to the deformation of the He {ii}\ lambda 4686 line and arises probably from a large scale structure in the low-velocity part of the stellar wind rather than from a photospheric phenomenon. We find that the time scale of the variability could be consistent with the estimated rotational period of HD 192639. Based on observations collected at the Observatoire de Haute Provence, France. [less ▲]

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See detailLine profiles in expanding envelopes
Surdej, Jean ULg

in Astronomy and Astrophysics (1979), 73

An attempt is made to show how the physical and geometrical parameters prevailing in an expanding stellar envelope can be inferred from an analysis of one or more observed line profiles. Attention is ... [more ▼]

An attempt is made to show how the physical and geometrical parameters prevailing in an expanding stellar envelope can be inferred from an analysis of one or more observed line profiles. Attention is given to the Sobolev approximation, line formation in outwardly accelerating envelopes, effects of a stellar core, and radiative transfer in outwardly decelerating envelopes. General equations are derived for both types of envelope, and some typical solutions are presented. Application of the method to P Cygni lines is discussed. [less ▲]

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See detailThe line spectrum of the solar Corona
Swings, Polydore ULg

in Publications of the Astronomical Society of the Pacific [=PASP] (1945), 57

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See detailLine-by-line calculations of thermal infrared radiation representative for global condition: CFC-12 as an example
Myhre, Gunnar; Stordal, Frode; Gausemel, Ingvil et al

in Journal of Quantitative Spectroscopy & Radiative Transfer (2006), 97(3), 317-331

We estimate a current direct radiative forcing due to CFC-12 of 0.18 Wm(-2), which is likely to be the peak radiative forcing for CFC-12. Global measurements of CFC-12 show at present an almost negligible ... [more ▼]

We estimate a current direct radiative forcing due to CFC-12 of 0.18 Wm(-2), which is likely to be the peak radiative forcing for CFC-12. Global measurements of CFC-12 show at present an almost negligible trend for CFC-12 and measurement in an industrialized region show evidence that the peak concentration is reached. It is expected that concentration of CFC-12 in industrialized regions begins to decline 1-3 years before the global concentration. Our radiative forcing calculations are based on a line-by-line model appropriate for simulation of global mean radiative forcing, including clouds and stratospheric temperature adjustment. The radiative forcing of 0.33 Wm(-2)/ppbv is close to earlier published results for this compound. New spectroscopic measurements for CFC-12 are performed and compared to previously published results. (C) 2005 Elsevier Ltd. All rights reserved. [less ▲]

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See detailA line-profile analysis of the large-amplitude beta Cephei star xi1 Canis Majoris
Saesen, S.; Briquet, Maryline ULg; Aerts, C.

in Communications in Asteroseismology (2006), 147

We present a detailed line-profile study of the beta Cephei star xi1 Canis Majoris, for which we have assembled numerous high-resolution spectra over a period of 4.5 years. It is the first time that the ... [more ▼]

We present a detailed line-profile study of the beta Cephei star xi1 Canis Majoris, for which we have assembled numerous high-resolution spectra over a period of 4.5 years. It is the first time that the line-profile variations of this star have been analysed. We focused on the Si III line profiles centered on 4560 A. We searched for oscillation frequencies in different line diagnostics and find the star to be monoperiodic with frequency f=4.77153 c/d. By means of the moment method and from amplitude and phase variations across the line profiles we identified the oscillation mode of the star as radial. xi1 CMa is among the very few beta Cephei stars with a radial-velocity amplitude larger than the local speed of sound and profile variations that clearly deviate from those predicted by linear oscillation theory. [less ▲]

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See detailLine-profile variability and mass-transfer in the early type binary BD+40° 4220
Vreux, Jean-Marie ULg; Rauw, Grégor ULg; Bohannan, B. et al

in Liege International Astrophysical Colloquia (1996)

Not Available

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See detailLine-Profile Variability in the Massive Binary System HD 149404
Nazé, Yaël ULg; Carrier, Fabien; Rauw, Grégor ULg

in Interacting Winds from Massive Stars (2002)

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See detailLine-profile variablity in the spectrum of WR22 around periastron: binary interaction or intrinsic variability ?
Rauw, Grégor ULg; Vreux, Jean-Marie ULg; Gosset, Eric ULg

in Liege International Astrophysical Colloquia (1996)

Not Available

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See detailA linear accelerator for levitated micro-objects
Sari, Ibrahim; Kraft, Michael ULg

in Sensors and Actuators. A, Physical (2015)

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See detailLinear amphiphilic diblock copolymers of lactide and 2-dimethylaminoethyl methacrylate using bifunctional-initiator and one-pot approaches
Kryuchkov, Maksym A.; Detrembleur, Christophe ULg; Bazuin, Géraldine

in Polymer (2014), 55(10), 2316-2324

Linear amphiphilic diblock copolymers of polylactide (PLA) and poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) were synthesized by atom transfer radical polymerization (ATRP) of DMAEMA followed by ring ... [more ▼]

Linear amphiphilic diblock copolymers of polylactide (PLA) and poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) were synthesized by atom transfer radical polymerization (ATRP) of DMAEMA followed by ring-opening polymerization (ROP) of LLA using the bifunctional initiator, 2′-hydroxyethyl 2-bromoisobutyrate. NMR showed that the resulting PLA block was racemic and a quaternization/precipitation technique showed that there were significant amounts of racemic PLA homopolymer. In addition, simultaneous ATRP of DMAEMA and ROP of l-lactide by tin octoate were conducted at varied temperatures, indicating 90 °C as a suitable compromise temperature; this one-pot process also led to racemization and P(L)LA homopolymer. The racemization was attributed to reversible deprotonation of LLA by the N(CH3)2 moiety of (P)DMAEMA and the PLA homopolymer impurity was related to in situ formation of lactoyl lactate (LA–LA) due to nucleophilic ring opening of lactide by the amino moieties of (P)DMAEMA. The methods presented can be useful for the preparation of PDMAEMA–b–PLA/PLA composites in a two-step process or in a single step, one-pot process. [less ▲]

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See detailLinear and curvilinear effects of inbreeding on production traits for walloon Holstein cows
Croquet, Coraline; Mayeres, Patrick; Gillon, Alain ULg et al

in Journal of Dairy Science (2007), 90(1), 465-471

The nonlinear effects of inbreeding were studied by comparing linear and curvilinear regression models of phenotypic performances on inbreeding coefficients for production traits (milk, fat, and protein ... [more ▼]

The nonlinear effects of inbreeding were studied by comparing linear and curvilinear regression models of phenotypic performances on inbreeding coefficients for production traits (milk, fat, and protein yields) of Holstein cows in their first lactation. Three different regression models (linear, quadratic, and cubic) were introduced separately into a single-trait, single-lactation, random regression test-day model. The significance of the different regression coefficients was studied based on a t-test after estimation of error variances and covariances associated with the different regression coefficients. All of the tested regression coefficients were significantly different from 0. The traditional regression coefficients of milk, fat, and protein yields on inbreeding were, respectively, -22.10, -1.10, and -0.72 kg for Holstein cows in their first lactation. However, the estimates of 305-d production losses for various classes of animals based on inbreeding coefficients showed that the effect of inbreeding was not a linear function of the percentage of inbreeding. The 305-d milk yield loss profiles attributable to inbreeding, obtained by the various regression models, were different. However, for inbreeding coefficients between 0 and 10%, these differences were small. [less ▲]

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See detailLinear and loglinear structural mean models to evaluate the benefits of an on-demand dosing regimens
Comté, Laetitia ULg; Vansteelandt, Stijn; Tousset, Eric et al

in Clinical Trials : Journal of the Society for Clinical Trials (2009), 6(5), 403-415

Background Structural mean models (SMM) can be used to estimate treatment efficacy when drug exposure varies. We applied SMM to evaluate the clinical benefits of a proton pump inhibitor prescribed to be ... [more ▼]

Background Structural mean models (SMM) can be used to estimate treatment efficacy when drug exposure varies. We applied SMM to evaluate the clinical benefits of a proton pump inhibitor prescribed to be taken as needed to alleviate epigastric pain. We also investigated a new diagnostic approach to evaluate model assumptions. Methods All patients were suffering from non-erosive reflux disease or functional ulcer-like dyspepsia and were prescribed a proton pump inhibitor to be taken as needed for relief of epigastric pain. The primary endpoint was a score variable that expresses the magnitude of gastro-intestinal symptoms at 8 weeks after randomization. We developed linear and loglinear versions of the SMM to derive an unbiased estimator of the reduction in symptom score as a function of exposure to the test drug. Semi-parametric models based on splines and corresponding simultaneous confidence bands identified the presence of potential interactions between drug exposure and baseline covariates. Results The on-demand dosing regimen generated a wide range of drug exposure. Application of SMM showed that the potential treatment induced reduction in symptom score was much greater than the average treatment reduction observed in this population of patients. Our diagnostic tool was useful for detecting the interaction between drug exposure and baseline covariates. Limitations Analysis could only be performed over the two first months after randomization because, afterwards, many patients dropped out from the placebo group. Conclusions The structural mean model approach allows one to estimate treatment efficacy in the presence of variable drug exposure. Similar results were obtained using linear and loglinear SMM. [less ▲]

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See detailLinear and Non-Linear Transonic Flow Behaviour of the Goland+ wing
Vio, Gareth Arthur; Dimitriadis, Grigorios ULg; Cooper, Jonathan Edward et al

in Proceedings of the 2007 International Forum on Aeroelasticity and Structural Dynamics (2007, June)

This paper is part of a study investigating the prediction of the aeroelastic behavior of aircraft subjected to transonic aerodynamic forces. The main objective of the work is the creation of Reduced ... [more ▼]

This paper is part of a study investigating the prediction of the aeroelastic behavior of aircraft subjected to transonic aerodynamic forces. The main objective of the work is the creation of Reduced Order Models from coupled Computational Fluid Dynamic and Finite Element calculations. The novelty of the approach lies in the identification of different types of Reduced Order Model in different flight regimes. Linear modal models are used in the Mach range range where the full CFD/CSD system is linear and nonlinear modal models in the transonic flight regime where the CFD/CSD system undergoes Limit Cycle Oscillations. Static solutions of the CFD/CSD system are used in order to determine the extent of the nonlinear Mach number range. The model treated in this work is a three-dimensional wing in a transonic flowfield. [less ▲]

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See detailLinear and nonlinear analyses of convective instabilities in evaporating liquid layers
Dauby, Pierre ULg; Dondlinger, Mireille; Marjerit, Jonathan et al

in Bulletin of the American Physical Society, Vol. 45, n°9 (2005, November)

The present work consists in a theoretical study of Rayleigh- B'enard-Marangoni instabilities in an evaporating horizontal liquid layer which is surmounted by a mixture of its vapour and an inert gas. The ... [more ▼]

The present work consists in a theoretical study of Rayleigh- B'enard-Marangoni instabilities in an evaporating horizontal liquid layer which is surmounted by a mixture of its vapour and an inert gas. The fluid and the gas mixture form a 2-layer system but simplified models can be built to analyse the behaviour of the system. In particular, a 1-layer model can be deduced by introducing a generalized Biot number. In the so- called 1.5-layer approximation, the behaviour of the gas is simplified by only keeping the linear equation of vapour diffusion. In the linear study of thermoconvective instabilities, both simplified models are shown to be in good agreement with the complete 2-layer system. For the non linear approach, only the simplified models are considered. A Galerkin-Eckhaus method is used to deduce amplitude equations for the weakly nonlinear analysis of the problem. The stability domains for the rolls, squares and hexagonal patterns emerging above threshold are determined. Both water and ethanol are used as fluids, while the inert gas is assumed to be air. [less ▲]

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See detailLinear and nonlinear analyses of convective instabilities in evaporating liquid layers
Dondlinger, M.; Margerit, J.; Dauby, Pierre ULg

in On Interfacial Fluid Dynamics And Processes in phyisico-chemical systems (2004)

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See detailLinear and nonlinear optical properties of functionalized CdSe quantum dots prepared by plasma sputtering and wet chemistry
Humbert, Christophe; Dahi, Abdellatif; Dalstein, Laetitia et al

in Journal of Colloid & Interface Science (2015), 445

Detailed reference viewed: 16 (4 ULg)