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See detailMode Identification and Seismic Modelling of the Cep Star EN(16)Lac
Aerts, C.; Lehmann, H.; Scuflaire, Richard ULg et al

in Asteroseismology Across the HR Diagram (2003)

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See detailMode identification based on time-series spectrophotometry for the bright rapid sdB pulsator EC 01541-1409
Randall, Suzanna K; Fontaine, Gilles; Geier, Stephan et al

in Astronomy and Astrophysics (2014), 563

We present an analysis of time-resolved spectrophotometry gathered with FORS/VLT for the rapidly pulsating hot B subdwarf EC 01541-1409 with the aim of identifying the degree index ℓ of the larger ... [more ▼]

We present an analysis of time-resolved spectrophotometry gathered with FORS/VLT for the rapidly pulsating hot B subdwarf EC 01541-1409 with the aim of identifying the degree index ℓ of the larger amplitude modes. This mode identification can be extremely useful in detailed searches for viable asteroseismic models in parameter space, and can be crucial for testing the validity of a solution a posteriori. To achieve it, we exploit the ℓ-dependence of the monochromatic amplitude, phase, and velocity-to-amplitude ratio of a mode as a function of wavelength. We use the ℓ-sensitive phase lag between the flux perturbation and the radial velocity as an additional diagnostic tool. On this basis, we are able to unambiguously identify the dominant 140.5 s pulsation of our target as a radial mode, and the second-highest amplitude periodicity at 145.8 s as an ℓ = 2 mode. We further exploit the exceptionally high-sensitivity data that we gathered for the dominant mode to infer modal properties that are usually quite difficult to estimate in sdB pulsators, namely the physical values of the dimensionless radius, temperature, and surface gravity perturbations. [less ▲]

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See detailMode identification from monochromatic amplitude and phase variations for the rapidly pulsating subdwarf B star EC 20338-1925
Randall, S. K.; Fontaine, G.; Brassard, P. et al

in Astronomy and Astrophysics (2010), 522

We obtain time-series spectrophotometry observations at the VLT with the aim of partially identifying the dominant oscillation modes in the rapidly pulsating subdwarf B star EC 20338-1925 on the basis of ... [more ▼]

We obtain time-series spectrophotometry observations at the VLT with the aim of partially identifying the dominant oscillation modes in the rapidly pulsating subdwarf B star EC 20338-1925 on the basis of monochromatic amplitude and phase variations. From the data gathered, we detect four previously known pulsations with periods near 147, 168, 126 and 140 s and amplitudes between 0.2 and 2.3 % of the star's mean brightness. We also determine the atmospheric parameters of EC 20338-1925 by fitting our non-LTE model atmospheres to an averaged combined spectrum. The inferred parameters are Teff = 34 153±94 K, log g = 5.966±0.017 and log N(He)/N(H) = -1.642±0.022, where the uncertainty estimates quoted refer to the formal fitting errors. Finally, we calculate the observed monochromatic amplitudes and phases for the periodicities extracted using least-squares fitting to the light curves obtained for each wavelength bin. These observed quantities are then compared to the corresponding theoretical values computed on the basis of dedicated model atmosphere codes and also taking into account non-adiabatic effects. We find that the quality of the data is sufficient to identify the dominant pulsation at 146.9 s as a radial mode, while two of the lower amplitude periodicities must be low-degree modes with ell = 0-2. This is the first time that monochromatic amplitudes and phases have been used for mode identification in a subdwarf B star, and the results are highly encouraging. [less ▲]

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See detailMode identification from spectroscopy
Briquet, Maryline ULg

Learning material (2008)

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See detailMode identification in rapidly pulsating subdwarf B stars from monochromatic amplitude- and phase variations
Randall, Suzanna K.; Van Grootel, Valérie ULg; Fontaine, Gilles et al

in Communications in Asteroseismology (2008, December), 157

We present a mid-term report on a project aimed at partially identifying the main modes of pulsation in the rapidly pulsating subdwarf B star PG 1047+003. Using the unique HIT-MS mode on FORS2 at the VLT ... [more ▼]

We present a mid-term report on a project aimed at partially identifying the main modes of pulsation in the rapidly pulsating subdwarf B star PG 1047+003. Using the unique HIT-MS mode on FORS2 at the VLT we obtained ˜3000 spectra spread over 4 consecutive half-nights with a typical sampling rate of 20 s. These will be used to extract monochromatic pulsation amplitudes and phases that can be fit to model predictions in order to determine the degree ℓ of the mode in question. [less ▲]

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See detailMode Identification in Subdwarf B Stars from Multi-Wavelength Observations
Randall, Suzanna K; Fontaine, Gilles; Brassard, Pierre et al

in Astronomical Society of the Pacific Conference Series (2014), 481

We present several examples of partial mode identification for rapidly pulsating subdwarf B stars on the basis of multi-colour observations. Three targets (V391 Per, Balloon 090100001, and EC 11583−2708 ... [more ▼]

We present several examples of partial mode identification for rapidly pulsating subdwarf B stars on the basis of multi-colour observations. Three targets (V391 Per, Balloon 090100001, and EC 11583−2708) were analysed from multi-colour photometry, while studies were conducted from time-series spectrophotometry for two further stars (EC 20338−1925 and EC 01541−1409). In all cases, periodicities strongly dominating the frequency spectrum are associated with radial modes, indicating a clear hierarchy according to visibility when integrating over the visible disk of the star. [less ▲]

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See detailMode identification using photometry and spectroscopy
De Ridder, Joris; Aerts, Conny; Dupret, Marc-Antoine ULg

in IAU Colloq. 193: Variable Stars in the Local Group (2004, May 01)

We tested a stepwise approach to combine photometry and spectroscopy for mode identificaiton where we first used the photometric amplitude ratios to restrict the degree l, then did a spectroscopic mode ... [more ▼]

We tested a stepwise approach to combine photometry and spectroscopy for mode identificaiton where we first used the photometric amplitude ratios to restrict the degree l, then did a spectroscopic mode identification, and finally fitted the photometric amplitudes to restrict the list of candidate modes. For the spectroscopic mode identification, we implemented an efficient multi-mode moment method variant. We conclude that this new variant works well, but that the photometric amplitudes are too model sensitive to do any additional mode discrimination. [less ▲]

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See detailMode lifetime and associated scaling relations
Belkacem, K.; Appourchaux, T.; Baudin, F. et al

in EPJ Web of Conferences (2013, March 01), 43

Thanks to the CoRoT and Kepler spacecrafts, scaling relations (linking seismic indices and global stellar parameters) are becoming the cornerstone of ensemble asteroseismology. Among them, the relation ... [more ▼]

Thanks to the CoRoT and Kepler spacecrafts, scaling relations (linking seismic indices and global stellar parameters) are becoming the cornerstone of ensemble asteroseismology. Among them, the relation between the cut-off frequency and the frequency of the maximum in the power spectrum of solar-like pulsators as well as the relation between mode lifetime and the effective temperature remain poorly understood. However, a solid theoretical background is essential to assess the accuracy of those relations and subsequently of the derived stellar parameters. We will thus present recent advances on the understanding of the underlying mechanisms governing those relations and show that the physics of mode lifetime (thus of mode damping) plays a major role. [less ▲]

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See detailMode of action of cis-dichloro-diammine platinum(II) on mouse Ehrlich ascites tumour cells.
Heinen, Ernst ULg; Bassleer, R.

in Biochemical Pharmacology (1976), 25(16), 1871-5

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See detailThe mode of action of diuretics
Lohrmann, E.; Nitschke, R. B.; Nitschke, R. et al

in Proc. XIth Int. Congr. Nephrol. Tokyo (1991)

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See detailMode of administration of Erythropoetin (rHu-Epo)- Does it matter?
BOVY, Christophe ULg; DUBOIS, Bernard ULg; popovic, Anne et al

in Nephrology Dialysis Transplantation (1995), 10

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See detailMode of interaction between β-lactam antibiotics and the exocellular DD-carboxypeptidase--transpeptidase from Streptomyces R39
Fuad, Noha; Frère, Jean-Marie ULg; Ghuysen, Jean-Marie ULg et al

in Biochemical Journal (1976), 155(3), 623-629

The exocellular DD-carboxypeptidase-transpeptidase of Streptomyces R39 is inhibited by beta-lactam antibiotics according to the same general scheme of reaction as the exocellular DD-carboxypeptidase ... [more ▼]

The exocellular DD-carboxypeptidase-transpeptidase of Streptomyces R39 is inhibited by beta-lactam antibiotics according to the same general scheme of reaction as the exocellular DD-carboxypeptidase-transpeptidase of Streptomyces R61. However, the values for the kinetic constants involved in the reaction are very different for the two enzymes and provide an explanation for the observation that the R39 enzyme is more sensitive to beta-lactam antibiotics than the R61 enzyme. Further, particular beta-lactams influence the kinetic constants to different extents depending on the source of the enzyme, so that a physical basis for the spectrum of antibiotic activity against particular enzyme systems is provided. [less ▲]

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See detailMode of Membrane Insertion and Sequence of a 32-Amino Acid Peptide Stretch of the Penicillin-Binding Protein 4 of Enterococcus Hirae
Jacques, Philippe; el Kharroubi, Aboubaker; Van Beeumen, Jozef et al

in FEMS Microbiology Letters (1991), 66(2), 119-123

Analysis of water-soluble derivatives of the Enterococcus hirae 75-kDa membrane-bound penicillin-binding protein 4 (PBP4) has yielded the amino acid sequence of a 32-amino acid polypeptide stretch. This ... [more ▼]

Analysis of water-soluble derivatives of the Enterococcus hirae 75-kDa membrane-bound penicillin-binding protein 4 (PBP4) has yielded the amino acid sequence of a 32-amino acid polypeptide stretch. This peptide is similar to peptide segments known to occur in the N-terminal domain of high-Mr PBPs of class B. The E. hirae PBP4 probably belongs to the same class. It is anchored in the membrane at the N-terminus of the polypeptide chain. [less ▲]

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See detailMode Of Membrane Interaction And Fusogenic Properties Of A De Novo Transmembrane Model Peptide Depend On The Length Of The Hydrophobic Core
Lorin, A.; Charloteaux, Benoît ULg; Fridmann-Sirkis, Y. et al

in Journal of Biological Chemistry (2007), 282(25), 18388-96

Model peptides composed of alanine and leucine residues are often used to mimic single helical transmembrane domains. Many studies have been carried out to determine how they interact with membranes ... [more ▼]

Model peptides composed of alanine and leucine residues are often used to mimic single helical transmembrane domains. Many studies have been carried out to determine how they interact with membranes. However, few studies have investigated their lipid-destabilizing effect. We designed three peptides designated KALRs containing a hydrophobic stretch of 14, 18, or 22 alanines/leucines surrounded by charged amino acids. Molecular modeling simulations in an implicit membrane model as well as attenuated total reflection-Fourier transform infrared analyses show that KALR is a good model of a transmembrane helix. However, tryptophan fluorescence and attenuated total reflection-Fourier transform infrared spectroscopy indicate that the extent of binding and insertion into lipids increases with the length of the peptide hydrophobic core. Although binding can be directly correlated to peptide hydrophobicity, we show that insertion of peptides into a membrane is determined by the length of the peptide hydrophobic core. Functional studies were performed by measuring the ability of peptides to induce lipid mixing and leakage of liposomes. The data reveal that whereas KALR14 does not destabilize liposomal membranes, KALR18 and KALR22 induce 40 and 50% of lipid-mixing, and 65 and 80% of leakage, respectively. These results indicate that a transmembrane model peptide can induce liposome fusion in vitro if it is long enough. The reasons for the link between length and fusogenicity are discussed in relation to studies of transmembrane domains of viral fusion proteins. We propose that fusogenicity depends not only on peptide insertion but also on the ability of peptides to destabilize the two leaflets of the liposome membrane. [less ▲]

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See detailMode visibilities in rapidly rotating stars
Reese, Daniel ULg; Prat, V.; Barban, C. et al

in Astronomy and Astrophysics (2013), 550

Context: Mode identification is a crucial step to comparing observed frequencies with theoretical ones, but has proven to be difficult in rapidly rotating stars. Aims: To further constrain mode ... [more ▼]

Context: Mode identification is a crucial step to comparing observed frequencies with theoretical ones, but has proven to be difficult in rapidly rotating stars. Aims: To further constrain mode identification, we aim to accurately calculate mode visibilities and amplitude ratios in rapid rotators. Methods: We derive the relevant equations for calculating mode visibilities in different photometric bands while fully taking into account the geometric distortion from both the centrifugal deformation and the pulsation modes, the variations in effective gravity, and an approximate treatment of the temperature variations. These equations are then applied to 2D oscillation modes, calculated using the TOP code, in fully distorted 2D models based on the SCF method. The specific intensities come from a grid of Kurucz atmospheres, thereby taking into account limb and gravity darkening. Results: We obtain mode visibilities and amplitude ratios for 2 M_{\odot} models rotating at 0 to 80 % of the critical rotation rate. These calculations confirm previous results, such as the increased visibility of chaotic modes, the simpler frequency spectra of pole-on stars, or the dependence of amplitude ratios on inclination and azimuthal order. In addition, the geometric shape of the star reduces the contrast between pole-on and equator-on visibilities of island modes. We also show that modes with similar (ell, |m|) values frequently have similar amplitude ratios, even in the most rapidly rotating models. [less ▲]

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See detailModel Analysis: A Systems Theory Contribution to Systems Biology
Bullinger, Eric ULg

Scientific conference (2002, April 05)

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See detailA Model Based Study of Carbon Fluxes at Ten European Forest Sites
Falge, E.; Tenhunen, J.; Aubinet, Marc ULg et al

in Valentini, Riccardo (Ed.) Fluxes of Carbon, Water and Energy of European Forests (2003)

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See detailModel based, gain-scheduled anti-windup control for LPV systems
Forni, Fulvio ULg; Galeani, Sergio

in 46th IEEE Conference on Decision and Control (cdc 2007) (2007)

In this paper we show that a recently proposed technique for anti-windup control of exponentially unstable plants can be easily extended to solve the corresponding robust anti-windup problem for linear ... [more ▼]

In this paper we show that a recently proposed technique for anti-windup control of exponentially unstable plants can be easily extended to solve the corresponding robust anti-windup problem for linear parameter varying systems, for which the time varying parameters are measured online. For this class of plants, it is shown that the proposed technique is minimally conservative with respect to the size of the resulting operating region: in particular, such a region is (up to an arbitrarily small quantity) exactly the largest set on which asymptotic stability can be guaranteed for the considered plant, for the given saturation level and uncertainty characteristics. [less ▲]

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See detailModel calculations of the Sivers function satisfying the Burkardt sum rule
Courtoy, Aurore ULg; Scopetta, S.; Vento, V.

in Physical Review. D, Particles, Fields, Gravitation, and Cosmology (2009), 79(7),

It is shown that, at variance with previous analyses, the MIT bag model can explain the available data of the Sivers function and satisfies the Burkardt sum rule to a few percent accuracy. The agreement ... [more ▼]

It is shown that, at variance with previous analyses, the MIT bag model can explain the available data of the Sivers function and satisfies the Burkardt sum rule to a few percent accuracy. The agreement is similar to the one recently found in the constituent quark model. Therefore, these two model calculations of the Sivers function are in agreement with the present experimental and theoretical wisdom. © 2009 The American Physical Society. [less ▲]

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See detailModel Checking in Practice: An Analysis of the ACCESS.bus Protocol using SPIN
Boigelot, Bernard ULg; Godefroid, Patrice

in Lecture Notes in Computer Science (1996), 1051

This paper presents a case study of the use of model checking for analyzing an industrial protocol, the ACCESS.bus protocol. Our analysis of this protocol was carried out using SPIN, an automated ... [more ▼]

This paper presents a case study of the use of model checking for analyzing an industrial protocol, the ACCESS.bus protocol. Our analysis of this protocol was carried out using SPIN, an automated verification system which includes an implementation of model-checking algorithms. A model of the protocol was developed, and properties expressed by linear-time temporal-logic formulas were checked on this model. This analysis revealed subtle flaws in the design of the protocol. Developers who worked on implementations of ACCESS.bus were unaware of these flaws at a very late stage of their development process. We also present suggestions for solving the detected problems. [less ▲]

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