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
See detailPulsations in massive stars: effect of the atmosphere on the strange mode pulsations
Godart, Mélanie ULg; Dupret, Marc-Antoine ULg; Noels-Grötsch, Arlette ULg et al

in Proceedings of the International Astronomical Union (2011), 272

Recent space observations with CoRoT and ground-based spectroscopy have shown the presence of different types of pulsations in OB stars. These oscillations could be due to acoustic and gravity modes ... [more ▼]

Recent space observations with CoRoT and ground-based spectroscopy have shown the presence of different types of pulsations in OB stars. These oscillations could be due to acoustic and gravity modes, solar-like oscillations or even other pulsations of large growth rates. We present a first attempt at interpreting the latter as strange modes. [less ▲]

Detailed reference viewed: 11 (4 ULg)
See detailPulsations in O and B stars
Godart, Mélanie ULg

Conference (2010, June)

Detailed reference viewed: 8 (6 ULg)
Full Text
Peer Reviewed
See detailPulsations in white dwarf stars
Fontaine, Gilles; Bergeron, Pierre; Brassard, Pierre et al

in Proceedings of the International Astronomical Union (2014, February), 301

We first present a brief description of the six distinct families of pulsating white dwarfs that are now known. These are all opacity-driven pulsators showing low- to mid-order, low-degree gravity modes ... [more ▼]

We first present a brief description of the six distinct families of pulsating white dwarfs that are now known. These are all opacity-driven pulsators showing low- to mid-order, low-degree gravity modes. We then discuss some recent highlights that have come up in the field of white dwarf asteroseismology. [less ▲]

Detailed reference viewed: 5 (0 ULg)
See detailPulsations of an Evolved Self-consistently Distorted Star
Ouazzani, Rhita-Maria ULg; Dupret, Marc-Antoine ULg; Roxburgh, I. W. et al

in ASP Conference Proceeding, Vol. 462, 402 (2012, September 01)

A new two-dimensional (2D) non-perturbative method to compute accurate oscillation modes of rapidly rotating stars is presented. The 2D calculations fully take into account the centrifugal distortion of ... [more ▼]

A new two-dimensional (2D) non-perturbative method to compute accurate oscillation modes of rapidly rotating stars is presented. The 2D calculations fully take into account the centrifugal distortion of the star while the non-perturbative method includes the full influence of the Coriolis acceleration, and are used to compute oscillation modes of rapid rotators — high-order p-modes in δ Scuti stars, as well as low-order p- and g-modes in β Cephei stars. We compare the oscillation spectra obtained for centrifugally distorted polytropes with those of Reese et al. (2006), and give the first results for a realistic 2D model of a rapidly rotating 2 M[SUB]&sun;[/SUB] evolved star computed with the method developed by Roxburgh (2006). [less ▲]

Detailed reference viewed: 7 (1 ULg)
Full Text
See detailPulsations of rapidly rotating evolved stars
Ouazzani, Rhita-Maria ULg; Roxburgh, I. W.; Dupret, Marc-Antoine ULg

in proceedings of the 20th Stellar Pulsation Conference Series, Granada sept 2011 (2012), 1301

A new two dimensional non-perturbative code to compute accurate oscillation modes of rapidly rotating stars is presented. The 2D calculations fully take into account the centrifugal distorsion of the star ... [more ▼]

A new two dimensional non-perturbative code to compute accurate oscillation modes of rapidly rotating stars is presented. The 2D calculations fully take into account the centrifugal distorsion of the star while the non perturbative method includes the full influence of the Coriolis acceleration. This 2D non-perturbative code is used to study pulsational spectra of highly distorted evolved models of stars. 2D models of stars are obtained by a self consistent method which distorts spherically averaged stellar models a posteriori. We are also able to compute gravito-acoustic modes for the first time in rapidly rotating stars. We present the dynamics of pulsation modes in such models, and show regularities in their frequency spectra. [less ▲]

Full Text
Peer Reviewed
See detailPulsations of rapidly rotating stars. I. The ACOR numerical code
Ouazzani, Rhita-Maria ULg; Dupret, Marc-Antoine ULg; Reese, Daniel ULg

in Astronomy and Astrophysics (2012), 547

Context. Very high precision seismic space missions such as CoRoT and Kepler provide the means of testing the modeling of transport processes in stellar interiors. For some stars, such as solar-like and ... [more ▼]

Context. Very high precision seismic space missions such as CoRoT and Kepler provide the means of testing the modeling of transport processes in stellar interiors. For some stars, such as solar-like and red giant stars, a rotational splitting is measured. However, to fully exploit these splittings and constrain the rotation profile, one needs to be able to calculate them accurately. For some other stars, such as δ Scuti and Be stars, for instance, the observed pulsation spectra are modified by rotation to such an extent that a perturbative treatment of the effects of rotation is no longer valid. <BR /> Aims: We present here a new two-dimensional non-perturbative code called ACOR (adiabatic code of oscillation including rotation) that allows us to compute adiabatic non-radial pulsations of rotating stars without making any assumptions on the sphericity of the star, the fluid properties (i.e., baroclinicity) or the rotation profile. <BR /> Methods: The 2D non-perturbative calculations fully take into account the centrifugal distortion of the star and include the full influence of the Coriolis acceleration. The numerical method is based on a spectral approach for the angular part of the modes and a fourth-order finite differences approach for the radial part. <BR /> Results: We test and evaluate the accuracy of the calculations by comparing them with those coming from the TOP (two-dimensional oscillation program) for the same polytropic models. We illustrate the effects of rapid rotation on stellar pulsations through the phenomenon of avoided crossings. <BR /> Conclusions: As shown by the comparison with the TOP for simple models, the code is stable, and gives accurate results up to near-critical rotation rates. [less ▲]

Detailed reference viewed: 18 (5 ULg)
Full Text
Peer Reviewed
See detailPulse pressure and ambulatory arterial stiffness index (AASI) in patients wit type 1 diabetes
Philips, Jean-Christophe ULg; Marchand, Monique ULg; Saint-Remy, Annie ULg et al

Conference (2009, September 19)

Results of PP and AASI measurements performed during a 24H AMBP recording and a 3 min posture test are not superimposable, but gave complementary information, in a population with type 1 diabetes mellitus ... [more ▼]

Results of PP and AASI measurements performed during a 24H AMBP recording and a 3 min posture test are not superimposable, but gave complementary information, in a population with type 1 diabetes mellitus. Our proof-of-concept study does not support the use of AASI as a cardiovascular risk marker when calculated during a short posture test. [less ▲]

Detailed reference viewed: 8 (0 ULg)
Full Text
Peer Reviewed
See detailPulse pressure and cardiovascular autonomic neuropathy according to duration of type 1 diabetes.
Philips, Jean-Christophe ULg; Marchand, Monique ULg; Scheen, André ULg

in Diabetes/Metabolism Research & Reviews (2009)

BACKGROUND: To evaluate changes in pulse pressure (PP) and markers of cardiovascular autonomic neuropathy (CAN) according to duration of type 1 diabetes mellitus (T1DM). METHODS: This cross-sectional ... [more ▼]

BACKGROUND: To evaluate changes in pulse pressure (PP) and markers of cardiovascular autonomic neuropathy (CAN) according to duration of type 1 diabetes mellitus (T1DM). METHODS: This cross-sectional controlled study evaluated 159 diabetic patients during a 3-min posture test (standing-squatting-standing) with continuous measurement of systolic (SBP), diastolic (DBP) and mean (MBP) blood pressure by a Finapres device. Arterial stiffness was indirectly assessed by PP and the slope of PP as a function of MBP calculated during the whole 3-min test. CAN was assessed by the expiration/inspiration pulse interval ratio (E/I R-R ratio) during deep breathing and by three indices measured during the squatting test. Patients were divided into four groups according to diabetes duration (<10 years, 11-20 years, 21-30 years and > 30 years from group 1 to group 4, respectively) and compared with age-matched non-diabetic subjects. RESULTS: PP progressively increased (p < 0.0001) and PP/MBP decreased (p < 0.0005) according to T1DM duration, whereas these parameters remained almost unchanged in age-matched control subjects. E/I ratio (p < 0.0001) and baroreflex gain (p < 0.0005) progressively decreased with T1DM duration. The parasympathetic index (squatting test vagal ratio-SqTv) significantly increased (p < 0.0001), whereas the sympathetic index (squatting test sympathetic ratio-SqTs) only tended to decrease (p = 0.12) according to diabetes duration. No such changes in CAN indices were observed in the non-diabetic population. CONCLUSIONS: PP increased according to T1DM duration in an age range where PP remained almost stable in controls, in agreement with accelerated arterial stiffening due to chronic hyperglycaemia. The baroreflex gain decreased and other indices of CAN also deteriorated with diabetes duration, more so indices reflecting parasympathetic rather than sympathetic dysfunction. [less ▲]

Detailed reference viewed: 34 (3 ULg)
Full Text
Peer Reviewed
See detailPulse pressure and pulsatile stress in overweight/obese nonhypertensive patients with versus without type 2 diabetes.
Scheen, André ULg; Philips, Jean-Christophe ULg; Marchand, Monique ULg

in Obesity Reviews : An Official Journal of the International Association for the Study of Obesity (2010)

Detailed reference viewed: 36 (5 ULg)
Full Text
Peer Reviewed
See detailPulse pressure and pulsatile stress in overweight/obese patients versus lean subjects in absence of hypertension or diabetes.
Scheen, André ULg; Philips, Jean-Christophe ULg; Marchand, Monique ULg

in Obesity Reviews : An Official Journal of the International Association for the Study of Obesity (2010)

Detailed reference viewed: 24 (4 ULg)
Full Text
Peer Reviewed
See detailPulse pressure and pulse wave velocity as markers of arterial stiffness in patients with type 1 diabetes
Philips, Jean-Christophe ULg; Xhignesse, Patricia ULg; Marchand, Monique ULg et al

Conference (2009, October 19)

Type 1 diabetes was associated with an increase in both PP and PWV as compared to a nondiabetic population. In the diabetic population, a close correlation between the two indirect markers of arterial ... [more ▼]

Type 1 diabetes was associated with an increase in both PP and PWV as compared to a nondiabetic population. In the diabetic population, a close correlation between the two indirect markers of arterial stiffness was found and also between each of them and age (or diabetes duration), but not in controls. These observations support the concept of an earier arterial stiffness in type 1 diabetes with rather poor glycemic control. [less ▲]

Detailed reference viewed: 12 (1 ULg)
Full Text
See detailPulsed holographic interferometry with photorefractive crystals. Recent advances of the european “PHIFE” project
Georges, Marc ULg; Lemaire, Philippe; Pauliat, Gilles et al

Conference (2004, March)

Detailed reference viewed: 23 (0 ULg)
Full Text
Peer Reviewed
See detailPulsed-field magnetization of drilled bulk high-temperature superconductors: flux front propagation in the volume and on the surface
Lousberg, Grégory ULg; Fagnard, Jean-François ULg; Haanappel, Evert et al

in Superconductor Science and Technology (2009), (22), 125026

We present a method for characterizing the propagation of the magnetic flux in an artificially drilled bulk high-temperature superconductor (HTS) during pulsed-field magnetization. As the magnetic pulse ... [more ▼]

We present a method for characterizing the propagation of the magnetic flux in an artificially drilled bulk high-temperature superconductor (HTS) during pulsed-field magnetization. As the magnetic pulse penetrates the cylindrical sample, the magnetic flux density is measured simultaneously in 16 holes by means of microcoils that are placed across the median plane, i.e. at an equal distance from the top and bottom surfaces, and close to the surface of the sample. We discuss the time evolution of the magnetic flux density in the holes during a pulse and measure the time taken by the external magnetic flux to reach each hole. Our data show that the flux front moves faster in the median plane than on the surface when penetrating the sample edge; it then proceeds faster along the surface than in the bulk as it penetrates the sample further. Once the pulse is over, the trapped flux density inside the central hole is found to be about twice as large in the median plane as on the surface. This ratio is confirmed by modelling. [less ▲]

Detailed reference viewed: 64 (40 ULg)
Full Text
Peer Reviewed
See detailPump and probe of ultrafast charge reorganization in small peptides: A computational study through sudden ionizations
Kus, Tomasz ULg; Mignolet, Benoît ULg; Levine, R. D. et al

in Journal of Physical Chemistry A (2013), 117(40), 10513-10525

Detailed reference viewed: 13 (5 ULg)
Full Text
Peer Reviewed
See detailPump and probe ultrafast electron dynamics in LiH: a computational study
Nest, M.; Remacle, Françoise ULg; Levine, R. D.

in New Journal of Physics (2008), 10

A time-dependent multiconfiguration method with a large electronic basis set is used to compute the response of all the electrons of LiH to a few-cycle intense pump field followed by a probe pulse. The ... [more ▼]

A time-dependent multiconfiguration method with a large electronic basis set is used to compute the response of all the electrons of LiH to a few-cycle intense pump field followed by a probe pulse. The ultrashort pump pulse excites a coherent superposition of stationary electronic states and, by changing the pump parameters such as intensity, duration, polarization and phase of carrier frequency, one can steer the motion of the electrons. Particular attention is given to the control provided by the polarization and by the phase. For example, a change in polarization is used to select an electronic wave packet that is rotating in a plane perpendicular to the bond or rotation in a plane containing the bond. The electronic wave packet can be probed by a delayed second pulse. This delayed probe pulse is also included in the Hamiltonian with the result that the frequency dispersed probe spectrum can be computed and displayed as a two-dimensional plot. [less ▲]

Detailed reference viewed: 20 (2 ULg)
See detailPump up the volume! Mogelijkheid en onmogelijkheid van het manifest in postmoderne tijden
Spinoy, Erik ULg

in De Zingende Zaag (1994), (24-25), 102-123

This article reflects on the fact that manifests are a predominantly modernist genre. In postmodern times, manifests can only reappear as simulations or parodies.

Detailed reference viewed: 23 (0 ULg)
Full Text
Peer Reviewed
See detailPumpellyite-(Al), a new mineral from Bertrix, Belgian Ardennes
Hatert, Frédéric ULg; Pasero, Marco; Perchiazzi, Natale et al

in European Journal of Mineralogy (2007), 19(2, MAR-APR), 247-253

Pumpellyite-(Al), ideally Ca-2(Al,Fe2+,Mg)Al-2(SiO4)(Si2O7)(OH,O)(2)center dot H2O, is a newly approved mineral species from Bertrix, Ardennes mountains, Belgium. It occurs as radiating fibrous aggregates ... [more ▼]

Pumpellyite-(Al), ideally Ca-2(Al,Fe2+,Mg)Al-2(SiO4)(Si2O7)(OH,O)(2)center dot H2O, is a newly approved mineral species from Bertrix, Ardennes mountains, Belgium. It occurs as radiating fibrous aggregates reaching 5 mm in diameter, constituted by acicular crystals associated with calcite, K-feldspar and chlorite. Pumpellyite-(Al) is transparent to translucent and exhibits an emerald-green to white colour, sometimes with bluish tinges. The lustre is vitreous and the streak is colourless. The mineral is non-fluorescent, brittle, and shows a perfect {100} cleavage. The estimated Mobs hardness is 51/2, and the calculated density is 3.24 g/cm(3). Pumpellyite-(Al) is biaxial positive, alpha = 1.678(2), beta = 1.680(2), gamma = 1.691 (1) (lambda = 590 nm), colourless in thin section, 2V = 46 degrees, Y = b, no dispersion. Electron-microprobe analyses gave SiO2 37.52, Al2O3 25.63, MgO 1.99, FeO 4.97, MnO 0.11, CaO 23.21, BaO 0.01, Na2O 0.03, K2O 0.02, H2Ocalc. 6.71, total 100.20 wt. %. The resulting empirical formula, calculated on the basis of 8 cations, is (Ca1.99Na0.01)(Sigma 2.00)(Al0.42Fe0.332+Mg0.24Mn0.01)(Sigma 1.00)Al-2.00(SiO4)(Si2O7)(2.42) center dot 0.58H(2)O. The simplified formula is Ca2AlAl2(SiO4)(Si2O7)(OH)(3), which requires SiO2 38.16, Al2O3 32.38, CaO 23.74, H2O 5.72, Total 100.00 wt. %. The unit-cell parameters, refined from X-ray powder diffraction data, are: a = 8.818(2), b = 5.898(2), c = 19.126(6) angstrom, beta = 97.26(3)degrees, V = 986.7(4) angstrom(3), space group A2/m. The eight strongest lines in the powder pattern [d-values(in angstrom)(I)(hkl)] are: 4.371(65)(200), 3.787(80)(202), 3.040(70)(204), 2.912(95)(300), 2.895(100)(30 (2) over bar), 2.731(40)(20 (6) over bar), 2.630(35)(31 (1) over bar), 2.191(45)(40 (2) over bar). Pumpellyite-(Al) belongs to the pumpellyite group, and corresponds to the Al-rich compositions where the M1 and M2 sites contain Al as predominant cation. The crystal structure of pumpellyite-(Al) has been refined by the Rietveld method, based on an X-ray powder diffraction pattern, to R-Bragg = 7.09 %. The infrared spectrum is similar to those of minerals of the pumpellyite group. The mineral species and name were approved by the Commission on New Minerals and Mineral Names, IMA (no. 2005-016). [less ▲]

Detailed reference viewed: 44 (1 ULg)
Full Text
Peer Reviewed
See detailPumping picosecond optical parametric oscillators by a pulsed Nd:YAG laser mode locked using a nonlinear mirror
Mani, A. A.; Dreesen, Laurent ULg; Hollander, Ph. et al

in Applied Physics Letters (2001), 79(13), 1945-1947

We report on the performances of the mode locking of a flash-lamp-pumped Nd:YAG laser using a frequency-doubling nonlinear mirror combined with a two-photon absorber. Pulse lengths from 12 to 8 ps are ... [more ▼]

We report on the performances of the mode locking of a flash-lamp-pumped Nd:YAG laser using a frequency-doubling nonlinear mirror combined with a two-photon absorber. Pulse lengths from 12 to 8 ps are generated. We show that the flat shape of the pulse-train envelope generated by the oscillator is adapted for the synchronous pumping of optical parametric oscillators and we demonstrate the efficient generation of an infrared beam tunable from 3800 to 1100 cm-1 with bandwidth of 2 cm-1 in one single conversion stage in LiNbO3 or AgGaS2. The "all-solid-state" laser system enables surface sum-frequency generation spectroscopy to be performed with high sensitivity and high resolution. [less ▲]

Detailed reference viewed: 23 (0 ULg)
Full Text
Peer Reviewed
See detailPunch Press Vibration Isolation: a Case History
Golinval, Jean-Claude ULg; Géradin, Michel ULg

in European Journal of Mechanical and Environmental Engineering (1999), 44(3), 141-145

Detailed reference viewed: 29 (0 ULg)
Full Text
Peer Reviewed
See detailPunctuation effects in english and esperanto texts
Ausloos, Marcel ULg

in Physica a-Statistical Mechanics and Its Applications (2010), 389(14), 2835-2840

A statistical physics study of punctuation effects on sentence lengths is presented for written texts: Alice in wonderland and Through a looking glass. The translation of the first text into esperanto is ... [more ▼]

A statistical physics study of punctuation effects on sentence lengths is presented for written texts: Alice in wonderland and Through a looking glass. The translation of the first text into esperanto is also considered as a test for the role of punctuation in defining a style, and for contrasting natural and artificial, but written, languages. Several log-log plots of the sentence-length-rank relationship are presented for the major punctuation marks. Different power laws are observed with characteristic exponents. The exponent can take a value much less than unity (ca. 0.50 or 0.30) depending on how a sentence is defined. The texts are also mapped into time series based on the word frequencies. The quantitative differences between the original and translated texts are very minutes, at the exponent level. It is argued that sentences seem to be more reliable than word distributions in discussing an author style. (C) 2010 Published by Elsevier B.V. [less ▲]

Detailed reference viewed: 5 (0 ULg)