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
Peer Reviewed
See detailHarmonization of strategies for the validation of quantitative analytical procedures - A SFSTP proposal - Part II
Hubert, Philippe ULg; Nguyen-Huu, J.-J.; Boulanger, Bruno ULg et al

in Journal of Pharmaceutical & Biomedical Analysis (2007), 45(1), 70-81

As reported in a previous paper[1], the main objective of the new commission of the Societe Francaise des Sciences et Techniques Pharmaceutiques (SFSTP) was the harmonisation of approaches for the ... [more ▼]

As reported in a previous paper[1], the main objective of the new commission of the Societe Francaise des Sciences et Techniques Pharmaceutiques (SFSTP) was the harmonisation of approaches for the validation of quantitative analytical procedures. In a series of meetings, members of this Commission have first tried to review the objectives of analytical methods and the objectives of validation methods and to recommend the use of two-sided beta-expectation tolerance intervals for total error of validation samples (accuracy profile) in the acceptance/rejection of analytical method in validation phase. In the context of the harmonization, the other objectives were: (i) to propose a consensus on the norms usually recognized, while widely incorporating the ISO terminology; (ii) to recommend to validate the analytical procedure accordingly to the way it will be used in routine; (iii) to elaborate a rational, practical and statistically reliable strategy to assure the quality of the analytical results generated. This strategy has been formalised in a guide and the three latter objectives made by the Commission are summarised in the present paper which is the second part of summary report of the SFSTP commission. The SFSTP guide has been produced to help analysts to validate their analytical methods. It is the result of a consensus between professionals having expertise in analytical and/or statistical fields. The suggestions presented in this paper should therefore help the analyst to design and perform the minimum number validation experiments needed to obtain all the required information to establish and demonstrate the reliability of its analytical procedure. (C) 2007 Elsevier B.V. All rights reserved. [less ▲]

Detailed reference viewed: 160 (23 ULg)
Full Text
Peer Reviewed
See detailHarmonization of strategies for the validation of quantitative analytical procedures - A SFSTP proposal - Part III
Hubert, Philippe ULg; Nguyen-Huu, J. J.; Boulanger, Bruno ULg et al

in Journal of Pharmaceutical & Biomedical Analysis (2007), 45(1), 82-96

In the first two documents [Ph. Hubert, J.J. Nguyen-Huu, B. Boulanger, E. Chapuzet, P. Chiap, N. Cohen, P.A. Compagnon, W. Dewe, M. Feinberg. M. Lallier, M. Laurentie, N. Mercier, G. Muzard, C. Nivet, L ... [more ▼]

In the first two documents [Ph. Hubert, J.J. Nguyen-Huu, B. Boulanger, E. Chapuzet, P. Chiap, N. Cohen, P.A. Compagnon, W. Dewe, M. Feinberg. M. Lallier, M. Laurentie, N. Mercier, G. Muzard, C. Nivet, L. Valat, J. Pharm. Biomed. Anal. 36 (2004) 579-586; Ph. Hubert, J.J. Nguyen-Huu. B. Boulanger, E. Chapuzet, P. Chiap, N. Cohen, P.A. Compagnon, W. Dewe, M. Feinberg, M. Lallier, M. Laurentie, N. Mercier, G. Muzard. C. Nivet, L. Valat, E. Rozet, J. Pharm. Biomed. Anal., in press], a recent SFSTP Commission on the validation of analytical procedure has introduced a harmonized approach for the validation of analytical procedures. In order to complete this guide, the statistical methodology allowing to correctly conclude about the validity of a procedure is proposed in this third part of the guide. Indeed all the steps to obtain the decision tool namely the accuracy profile are described and illustrated step by step by a numerical example. This tool, based on the concept of total error (bias + standard deviation) build with a P-expectation tolerance interval, allows to easily take the right decision and simultaneously minimizing the risk of the future use of the analytical procedure. (C) 2007 Elsevier B.V. All rights reserved. [less ▲]

Detailed reference viewed: 146 (22 ULg)
Full Text
Peer Reviewed
See detailHarmonization of strategies for the validation of quantitative analytical procedures: a SFSTP proposal part IV. Examples of application.
Hubert, Philippe ULg; Nguyen-Huu, J.-J.; Boulanger, Bruno ULg et al

in Journal of Pharmaceutical & Biomedical Analysis (2008), 48(3), 760-71

A harmonized approach for the validation of analytical methods based on accuracy profile was introduced by a SFSTP commission on the validation of analytical procedure. This fourth and last document aims ... [more ▼]

A harmonized approach for the validation of analytical methods based on accuracy profile was introduced by a SFSTP commission on the validation of analytical procedure. This fourth and last document aims at illustrating this methodology and the statistics used. Therefore the validation of real case methods are proposed such as methods for the quality control of drugs, for the quantitation of impurities in drug substances, for bioanalysis or for the determination of nutriments. Furthermore, different types of analytical methods are used in order to demonstrate the applicability of the proposed approach to a wide range of methods such as liquid chromatography (LC-UV, LC-MS), spectrophotometry or ELISA. [less ▲]

Detailed reference viewed: 133 (31 ULg)
Peer Reviewed
See detailHarmonization of the Law of Succession in Europe
Leleu, Yves-Henri ULg; Verbeke, Alain-Laurent

in Hartkamp, S.; Hesselink, M.W.; Hondius, E. (Eds.) et al Towards a European civil Code (2010)

Detailed reference viewed: 11 (1 ULg)
Full Text
See detailHarmonization of the Law of Succession in Europe
Leleu, Yves-Henri ULg; Verbeke, Alain

in Hartkamp, A. (Ed.) Towards a European Civil Code (2004)

Detailed reference viewed: 41 (2 ULg)
Full Text
See detailHarmonization tests
Chirici, Gherardo; McRoberts, Ronald E.; Winter, Susanne et al

in Chirici, Gherardo; Winter, Susanne; McRoberts, Ronald E. (Eds.) National Forest Inventories - contributions to Forest Biodiversity Assessments (2011)

Chapter 5 reports the results of testing the proposed prodedures for harmonizing estimates of indicators for six of the seven essential features of forest biodiversity. Twenty indicators were tested using ... [more ▼]

Chapter 5 reports the results of testing the proposed prodedures for harmonizing estimates of indicators for six of the seven essential features of forest biodiversity. Twenty indicators were tested using data from the common database. In general, positive results were obtained for forest categories, forest structure, forest age, deadwood, and naturalness; the results were less positive for ground vegetation because of the considerable differences in definitions and data acquisition methods. Of importance is, that the test focused on assessing harmonization procedures rather than on producing comprehensive estimates for particular countries or forest categories. [less ▲]

Detailed reference viewed: 22 (10 ULg)
Full Text
Peer Reviewed
See detailHarmonized Growth Models and Simulations of the Evolution of Pure Stands of Norway spruce, Larches and Douglas-fir for Southern Belgium (Wallonia).
Perin, Jérôme ULg; Ligot, Gauthier ULg; Cerisier, François ULg et al

Poster (2012, March 02)

In order to compare different silvicultural scenarios we have undertaken the development of a software that can simulate stand evolution in regards to their species composition, site characteristics and ... [more ▼]

In order to compare different silvicultural scenarios we have undertaken the development of a software that can simulate stand evolution in regards to their species composition, site characteristics and silvicultural operations. As a first approach we limited the scope of our work to even-aged and pure coniferous stands of the three most important coniferous species in Wallonia (southern part of Belgium): Norway spruce (Picea abies), douglas-fir (Pseudotsuga menziensii) and larches (Larix sp.). This presentation introduces carried out simulations and compare their outcomes. First we gathered data sets from the permanent regional inventory, from observation networks and experimental plots throughout Wallonia. Then we adjusted, for these species, harmonized and distance-independent models of dominant-height growth, tree diameter growth, mortality, and the distribution of tree diameter frequency before the first thinning. Next we implemented those models in the Capsis platform, and we simulated, for the three species, the evolution of virtual stands using different scenarios. On one hand the evolution was performed without thinning, and on the other hand we applied silvicultural scenarios that are commonly used in Wallonia. As a result these models highlight, for example, the great juvenile growth and sensibility to stands density of larches whereas Norway spruce behaves the opposite. Further work is however needed to predict and simulate wood quality and value. Once this will be achieved we will attempt to optimize silvicultural scenarios for the three species. [less ▲]

Detailed reference viewed: 56 (18 ULg)
Full Text
See detailHaro sur la fouine ?
Libois, Roland ULg

Learning material (1992)

Detailed reference viewed: 12 (0 ULg)
Peer Reviewed
See detailHaroun and the Sea of Stories
Delrez, Marc ULg

Conference (1991)

Detailed reference viewed: 11 (0 ULg)
Full Text
See detailThe HARPS search for southern extra-solar planets XXXII. Only 4 planets in the Gl~581 system
Forveille, T.; Bonfils, X.; Delfosse, X. et al

E-print/Working paper (2011)

The Gl 581 planetary system has generated wide interest, because its 4 planets include both the lowest mass planet known around a main sequence star other than the Sun and the first super-Earth planet in ... [more ▼]

The Gl 581 planetary system has generated wide interest, because its 4 planets include both the lowest mass planet known around a main sequence star other than the Sun and the first super-Earth planet in the habitable zone of its star. A recent paper announced the possible discovery of two additional super-Earth planets in that system, one of which would be in the middle of the habitable zone of Gl 581. The statistical significance of those two discoveries has, however, been questioned. We have obtained 121 new radial velocity measurements of Gl 581 with the HARPS spectrograph on the ESO 3.6 m telescope, and analyse those together with our previous 119 measurements of that star to examine these potential additional planets. We find that neither is likely to exist with their proposed parameters. We also obtained photometric observations with the 2.5 m Isaac Newton Telescope during a potential transit of the inner planet, Gl 581e, which had a 5% geometric transit probability. Those observations exclude transits for planet densities under 4 times the Earth density within -0.2 sigma to +2.7 sigma of the predicted transit center. [less ▲]

Detailed reference viewed: 29 (1 ULg)
Full Text
Peer Reviewed
See detailThe HARPS search for southern extra-solar planets XXXV. Super-Earths around the M-dwarf neighbors Gl433 and Gl667C
Delfosse, X.; Bonfils, X.; Forveille, T. et al

in Astronomy and Astrophysics (2012), 553

Context. M dwarfs have often been found to have super-Earth planets with short orbital periods. These stars are thus preferential targets in searches for rocky or ocean planets in the solar neighborhood ... [more ▼]

Context. M dwarfs have often been found to have super-Earth planets with short orbital periods. These stars are thus preferential targets in searches for rocky or ocean planets in the solar neighborhood. Aims: Our research group recently announced the discovery of one and two low-mass planets around the M1.5V stars Gl 433 and Gl 667C, respectively. We found these planets with the HARPS spectrograph on the ESO 3.6-m telescope at La Silla Observatory, from observations obtained during the guaranteed time observing program of that instrument. Methods: We obtained additional HARPS observations of those two stars, for a total of 67 and 179 radial velocity measurements for Gl 433 and Gl 667C, respectively, and present here an orbital analysis of these extended data sets and our main conclusions about both planetary systems. Results: One of the three planets, Gl 667Cc, has a mass of only M2sini ~ 4.25 M⊕ and orbits in the central habitable zone of its host star. It receives only 10% less stellar energy from Gl 667C than the Earth receives from the Sun. However, planet evolution in the habitable zone can be very different if the host star is a M dwarf or a solar-like star, without necessarily questioning the presence of water. The two other planets, Gl 433b and Gl 667Cb, both have M2sini of ~5.5 M⊕ and periods of ~7 days. The radial velocity measurements of both stars contain longer timescale signals, which we fit with longer period Keplerians. For Gl 433, the signal probably originates in a magnetic cycle, while data of longer time span will be needed before conclusive results can be obtained for Gl 667C. The metallicity of Gl 433 is close to solar, while Gl 667C is metal poor with [Fe/H] ~ -0.6. This reinforces the recent conclusion that the occurrence of super-Earth planets does not strongly correlate with the stellar metallicity. [less ▲]

Detailed reference viewed: 20 (1 ULg)
Full Text
Peer Reviewed
See detailThe HARPS search for southern extra-solar planets. X. A m sin i = 11 M_â planet around the nearby spotted M dwarf <ASTROBJ>GJ 674</ASTROBJ>
Bonfils, X.; Mayor, M.; Delfosse, X. et al

in Astronomy and Astrophysics (2007), 474

Context: How planet properties depend on stellar mass is a key diagnostic of planetary formation mechanisms. Aims: This motivates planet searches around stars that are significantly more massive or less ... [more ▼]

Context: How planet properties depend on stellar mass is a key diagnostic of planetary formation mechanisms. Aims: This motivates planet searches around stars that are significantly more massive or less massive than the Sun, and in particular our radial velocity search for planets around very low-mass stars. Methods: As part of that program, we obtained measurements of <ASTROBJ>GJ 674</ASTROBJ>, an M 2.5 dwarf at d = 4.5 pc. These measurements have dispersion much in excess of their internal errors. An intensive observing campaign demonstrates that the excess dispersion is due to two superimposed coherent signals, with periods of 4.69 and 35 days. Results: These data are described well by a 2-planet Keplerian model where each planet has a ~11 M_â minimum mass. A careful analysis of the (low-level) magnetic activity of <ASTROBJ>GJ 674</ASTROBJ>, however, demonstrates that the 35-day period coincides with the stellar rotation period. This signal therefore originates in a spot inhomogeneity modulated by stellar rotation. The 4.69-day signal, on the other hand, is caused by a bona-fide planet, <ASTROBJ>GJ 674b</ASTROBJ>. Conclusions: Its detection adds to the growing number of Neptune-mass planets around M-dwarfs and reinforces the emerging conclusion that this mass domain is much more populated than the Jovian mass range. We discuss the metallicity distributions of M dwarf with and without planets and find a low 11% probability that they are drawn from the same parent distribution. Moreover, we find tentative evidence that the host star metallicity correlates with the total mass of their planetary system. Based on observations made with the HARPS instrument on the ESO 3.6 m telescope under the GTO program ID 072.C-0488 at Cerro La Silla (Chile). Radial-velocity, photometric and Ca II H+K index time series are only available in electronic format the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strabg.fr/cgi-bin/qcat?J/A+A/474/293 [less ▲]

Detailed reference viewed: 32 (1 ULg)
Full Text
Peer Reviewed
See detailThe HARPS search for southern extra-solar planets. XIV. Gl 176b, a super-Earth rather than a Neptune, and at a different period
Forveille, T.; Bonfils, X.; Delfosse, X. et al

in Astronomy and Astrophysics (2009), 493

A 10.24-day Neptune-mass planet was recently announced as orbiting the nearby M2 dwarf Gl 176, based on 28 radial velocities measured with the HRS spectrograph on the Hobby-Heberly Telescope. We obtained ... [more ▼]

A 10.24-day Neptune-mass planet was recently announced as orbiting the nearby M2 dwarf Gl 176, based on 28 radial velocities measured with the HRS spectrograph on the Hobby-Heberly Telescope. We obtained 57 radial velocities of Gl 176 with the ESO 3.6 m telescope and the HARPS spectrograph, which is known for its sub-m s[SUP]-1[/SUP] stability. The median photon-noise standard error of our measurements is 1.1 m s[SUP]-1[/SUP], significantly lower than the 4.7 m s[SUP]-1[/SUP] of the HET velocities, and the 4-year period over which they were obtained overlaps considerably with the epochs of the HET measurements. The HARPS measurements show no evidence of a signal at the period of the putative HET planet, suggesting that its detection was spurious. We do find, on the other hand, strong evidence of a lower mass 8.4 M_Earth planet, in a quasi-circular orbit and at the different period of 8.78 days. The host star has moderate magnetic activity and rotates on a 39-day period, which we confirm through modulation of both contemporaneous photometry and chromospheric indices. We detect that period, as well, in the radial velocities, but it is well removed from the orbital period and offers no cause for confusion. This new detection of a super-Earth (2 M_Earth < M sin (i) < 10 M_Earth) around an M dwarf adds to the growing evidence that such planets are common around very low-mass stars. A third of the 20 known planets with M sin (i)< 0.1 M_Jup and 3 of the 7 known planets with M sin (i) < 10 M_Earth orbit an M dwarf, in contrast to just 4 of the ~300 known Jupiter-mass planets. Based on observations made with the HARPS instrument on the ESO 3.6-m telescope at La Silla Observatory under program ID 072.C-0488. [less ▲]

Detailed reference viewed: 28 (1 ULg)
Full Text
See detailThe HARPS search for southern extra-solar planets. XXXIV. A planetary system around the nearby M dwarf GJ163, with a super-Earth possibly in the habitable zone
Bonfils, X.; Lo Curto, G.; Correia, A. C. M. et al

E-print/Working paper (2013)

The meter-per-second precision achieved by today velocimeters enables the search for 1-10 M_Earth planets in the habitable zone of cool stars. This paper reports on the detection of 3 planets orbiting ... [more ▼]

The meter-per-second precision achieved by today velocimeters enables the search for 1-10 M_Earth planets in the habitable zone of cool stars. This paper reports on the detection of 3 planets orbiting GJ163 (HIP19394), a M3 dwarf monitored by our ESO/HARPS search for planets. We made use of the HARPS spectrograph to collect 150 radial velocities of GJ163 over a period of 8 years. We searched the RV time series for coherent signals and found 5 distinct periodic variabilities. We investigated the stellar activity and casted doubts on the planetary interpretation for 2 signals. Before more data can be acquired we concluded that at least 3 planets are orbiting GJ163. They have orbital periods of P_b=8.632+-0.002, P_c=25.63+-0.03 and P_d=604+-8 days and minimum masses msini = 10.6+-0.6, 6.8+-0.9, and 29+-3 M_Earth, respectively. We hold our interpretations for the 2 additional signals with periods P_(e)=19.4 and P_(f)=108 days. The inner pair presents an orbital period ratio of 2.97, but a dynamical analysis of the system shows that it lays outside the 3:1 mean motion resonance. GJ163c, in particular, is a super-Earth with an equilibrium temperature of T_eq = (302+-10) (1-A)^(1/4) K and may lie in the so called habitable zone for albedo values (A=0.34-0.89) moderately higher than that of Earth (A_Earth=0.2-0.3). [less ▲]

Detailed reference viewed: 8 (0 ULg)
Full Text
Peer Reviewed
See detailThe HARPS search for southern extra-solar planets: XXXI. The M-dwarf sample
Bonfils, X.; Delfosse, X.; Udry, S. et al

in Astronomy and Astrophysics (2013), 549

(Abridged) Searching for planets around stars with different masses probes the outcome of planetary formation for different initial conditions. This drives observations of a sample of 102 southern nearby ... [more ▼]

(Abridged) Searching for planets around stars with different masses probes the outcome of planetary formation for different initial conditions. This drives observations of a sample of 102 southern nearby M dwarfs, using a fraction of our guaranteed time on the ESO/HARPS spectrograph (Feb. 11th, 2003 to Apr. 1st 2009). This paper makes available the sample's time series, presents their precision and variability. We apply systematic searches and diagnostics to discriminate whether the observed Doppler shifts are caused by stellar surface inhomogeneities or by the radial pull of orbiting planets. We recover the planetary signals corresponding to 9 planets already announced by our group (Gl176b, Gl581b, c, d & e, Gl674b, Gl433b, Gl 667Cb and c). We present radial velocities that confirm GJ 849 hosts a Jupiter-mass planet, plus a long-term radial-velocity variation. We also present RVs that precise the planetary mass and period of Gl 832b. We detect long-term RV changes for Gl 367, Gl 680 and Gl 880 betraying yet unknown long-period companions. We identify candidate signals in the radial-velocity time series and demonstrate they are most probably caused by stellar surface inhomogeneities. Finally, we derive a first estimate of the occurrence of M-dwarf planets as a function of their minimum mass and orbital period. In particular, we find that giant planets (m sin i = 100-1,000 Mearth) have a low frequency (e.g. f<1% for P=1-10 d and f=0.02^{+0.03}_{-0.01} for P=10-100 d), whereas super-Earths (m sin i = 1-10 Mearth) are likely very abundant (f=0.36^{+0.25}_{-0.10} for P=1-10 d and f=0.35^{+0.45}_{-0.11} for P=10-100 d). We also obtained eta_earth=0.41^{+0.54}_{-0.13}, the frequency of habitable planets orbiting M dwarfs (1<m sin i<10 Mearth). For the first time, eta_earth is a direct measure and not a number extrapolated from the statistic of more massive and/or shorter-period planets. [less ▲]

Detailed reference viewed: 16 (1 ULg)
Full Text
Peer Reviewed
See detailHartree-Fock instabilities and electronic properties
Dehareng, Dominique ULg; Dive, Georges ULg

in Journal of Computational Chemistry (2000), 21(6), 483-504

Hartree-Fock instabilities are investigated for about 80 compounds, from acetylene to mivazerol (27 atoms) and a cluster of 18 water molecules, within a double zeta basis set. For most conjugated systems ... [more ▼]

Hartree-Fock instabilities are investigated for about 80 compounds, from acetylene to mivazerol (27 atoms) and a cluster of 18 water molecules, within a double zeta basis set. For most conjugated systems, the restricted Hartree-Fock wave function of the singlet fundamental state presents an external or so-called triplet instability. This behavior is studied in relation with the electronic correlation, the vicinity of the triplet and singlet excited states, the electronic delocalization linked with resonance, the nature of eventual heteroatoms, and the size of the systems. The case of antiaromatic systems is different, because they may present a very large internal Hartree-Fock instability. Furthermore, the violation of Hund's rule, observed for these compounds, is put in relation with the fact that the high symmetry structure in its singlet state has no feature of a diradical-like species. It appears that the triplet Hartree-Fock instability is directly related with the spin properties of nonnull orbital angular momentum electronic systems. (C) 2000 John Wiley & Sons, Inc. [less ▲]

Detailed reference viewed: 29 (3 ULg)
Full Text
Peer Reviewed
See detailHartree-Fock instabilities: Relation between an artifact and some properties.
Dehareng, Dominique ULg; Dive, Georges ULg; Geron, Christine

in Recent Research Development in Chemical Physics (2002), 3

The Hartree-Fock instability problem is reviewed and some of the instabilities are put in relation with particular properties of the system.

Detailed reference viewed: 43 (1 ULg)
Full Text
Peer Reviewed
See detailThe Hartree-Fock triplet instability: influence of conformation and substitution
Géron, Christine; Dive, Georges ULg; Dehareng, Dominique ULg

in Journal of Molecular Structure-theochem (2006), 760(1-3), 75-85

The triplet Hartree-Fock (HF) instability is investigated through the examples of substituted ethylenes and the small linear conjugated systems butadiene, hexatriene, octatetraene. A statistical analysis ... [more ▼]

The triplet Hartree-Fock (HF) instability is investigated through the examples of substituted ethylenes and the small linear conjugated systems butadiene, hexatriene, octatetraene. A statistical analysis is performed for several conformations of the latters. The second eigenvalue of the instability matrix appears to be able to discriminate the groups of unsaturated compounds. The HF instability is largely influenced by conjugation and mesomeric effects and thus by the geometry. The number of pi electrons is also an important factor. The electronic correlation related to the HF instability is not quantified by the energy difference between the post-HF and HF levels. (c) 2005 Elsevier B.V. All rights reserved. [less ▲]

Detailed reference viewed: 45 (3 ULg)