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See detailPrécis historique de la découverte de la nutation diurne
Folie, François ULg

in Annuaire de l'Observatoire Royal de Belgique (1897), 64

The author summarizes his constants determination of the diurnal nutation and the obstacles which he had to overcome to reach his goal.

Peer Reviewed
See detailPrecise demarcation of the breakpoint in a thoroughbred stallion carrying a ECA5 and ECA16 Translocation.
Durkin, Keith ULg; Raudsepp, T; Chowdhary, B.P.

in Proceedings of Plant & Animal Genome XVI (2008, January)

Detailed reference viewed: 14 (1 ULg)
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See detailPrecise localization of antigens on follicular dendritic cells.
Radoux, D.; Heinen, Ernst ULg; Kinet-Denoel, C. et al

in Cell & Tissue Research (1984), 235(2), 267-74

Horse-spleen ferritin or bovine serum albumin conjugated to colloidal gold (BSA-gold) were injected subcutaneously in preimmunized mice. In draining lymph nodes both antigens were located in macrophages ... [more ▼]

Horse-spleen ferritin or bovine serum albumin conjugated to colloidal gold (BSA-gold) were injected subcutaneously in preimmunized mice. In draining lymph nodes both antigens were located in macrophages or between the cytoplasmic processes of follicular dendritic cells (FDC). Some of the antigens remained trapped on FDC until day 31 after injection. Simultaneous injection of both antigens showed that they were located between the infoldings of the same FDC. These cells are thus able to retain at least two different antigens on their surface. The peculiar arrangement of ferritin between the cytoplasmic infoldings suggests that this antigen is fixed on both cell membranes by specific antibodies. The trapped immune complexes could thus stabilize the FDC membrane system. The antigen retention requires the presence of specific antibodies since BSA-gold or ferritin injected without preimmunization were not found between FDC processes. Nonantigenic materials, such as colloidal gold or carbon particles, are not trapped by FDC, except when injected in large amounts. The antigens were trapped on the surface of FDC, however unfrequently in close contact with lymphocytes. FDC might protect lymphocytes against an excess of immune complexes and act as regulators of contacts between lymphocytes and immune complexes. [less ▲]

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See detailPrecise Point Positioning: Performances under Ionospheric Scintillations
Lonchay, Matthieu ULg

Report (2012)

The Precise Point Positioning (PPP) has become a powerful satellite positioning technique which nearly equals performances provided by advanced relative positioning techniques. Exploiting the growing ... [more ▼]

The Precise Point Positioning (PPP) has become a powerful satellite positioning technique which nearly equals performances provided by advanced relative positioning techniques. Exploiting the growing availability and quality of IGS products (satellite orbit and clock products), the PPP technique can now provide a centimetre level solution in static mode and a decimetre level in kinematic mode. However, the PPP technique still presents some weaknesses. In order to reach a high precision level, it requires a significant convergence period which can typically reach 30 minutes under normal conditions. Moreover, the PPP seems to be especially sensitive to ionospheric scintillations effects which involve signal amplitude and phase variations of GNSS signals. These weaknesses still limit the use of the PPP technique in the frame of some specific and demanding applications (agricultural industry, airborne mapping, etc.). The goal of our research project is to develop new data processing strategies attempting both to make the PPP technique more reliable under ionospheric scintillations and to optimize the PPP convergence time. The project is composed of several workpackages aiming to improve the mentioned current PPP weaknesses with specific strategies. One of the workpackages is devoted to the impact of satellite geometry on PPP performances. Ionospheric scintillations are susceptible to reduce the number of tracked satellites which degrades the quality of satellite geometry. Based on an analytical development, we first attempt to figure out what types of satellite geometry can be harmful. Then, we discuss about the improvement of the satellite geometry quality involved by the combined use of GPS and Galileo and its benefits in the frame of the PPP. Another workpackage is related to the weighting scheme. Based on an iterative least-square adjustment, the PPP algorithm requires the definition of a stochastic model composed of an observation covariance matrix. Usually, this matrix is chosen as diagonal with zero covariances assuming that correlations between observations can be neglected. In particular, our project aims to study the validity of this stochastic model for the PPP in order to determine whether tuning the weighting scheme of the stochastic model can improve the PPP performances. By exploiting spatial analysis techniques, we try to characterize the spatial auto-correlation between GNSS observations, considering the signal-to-noise ratio as the main observable. From the results of these experiments, we will discuss about the spatial correlation between GNSS observations both under normal conditions and ionospheric scintillations. [less ▲]

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See detailPrecise Point Positioning: Performances under Ionospheric Scintillations
Lonchay, Matthieu ULg; Aquino, Marcio; Hancock, Craig et al

Scientific conference (2012, June 14)

The Precise Point Positioning (PPP) has become a powerful satellite positioning technique which nearly equals performances provided by advanced relative positioning techniques. Exploiting the growing ... [more ▼]

The Precise Point Positioning (PPP) has become a powerful satellite positioning technique which nearly equals performances provided by advanced relative positioning techniques. Exploiting the growing availability and quality of IGS products (satellite orbit and clock products), the PPP technique can now provide a centimetre level solution in static mode and a decimetre level in kinematic mode. However, the PPP technique still presents some weaknesses. In order to reach a high precision level, it requires a significant convergence period which can typically reach 30 minutes under normal conditions. Moreover, the PPP seems to be especially sensitive to ionospheric scintillations effects which involve signal amplitude and phase variations of GNSS signals. These weaknesses still limit the use of the PPP technique in the frame of some specific and demanding applications (agricultural industry, airborne mapping, etc.). The goal of our research project is to develop new data processing strategies attempting both to make the PPP technique more reliable under ionospheric scintillations and to optimize the PPP convergence time. The project is composed of several workpackages aiming to improve the mentioned current PPP weaknesses with specific strategies. One of the workpackages is devoted to the impact of satellite geometry on PPP performances. Ionospheric scintillations are susceptible to reduce the number of tracked satellites which degrades the quality of satellite geometry. Based on an analytical development, we first attempt to figure out what types of satellite geometry can be harmful. Then, we discuss about the improvement of the satellite geometry quality involved by the combined use of GPS and Galileo and its benefits in the frame of the PPP. Another workpackage is related to the weighting scheme. Based on an iterative least-square adjustment, the PPP algorithm requires the definition of a stochastic model composed of an observation covariance matrix. Usually, this matrix is chosen as diagonal with zero covariances assuming that correlations between observations can be neglected. In particular, our project aims to study the validity of this stochastic model for the PPP in order to determine whether tuning the weighting scheme of the stochastic model can improve the PPP performances. By exploiting spatial analysis techniques, we try to characterize the spatial auto-correlation between GNSS observations, considering the signal-to-noise ratio as the main observable. From the results of these experiments, we will discuss about the spatial correlation between GNSS observations both under normal conditions and ionospheric scintillations. [less ▲]

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See detailPrecise Through Wall Angular Position Sensor Compatible with Cryogenic Temperature for Space Launcher
Carapelle, Alain ULg; Martin, Nicolas ULg; Chantraine, Thierry ULg

in Sensor Letters (2013), 11(10), 1992-1995

A new rotation sensor is developed and tested for the next generation of Ariane space launchers. It aimed at measuring accurately the angular position of an admission valve (target sensitivity of 0.01° ... [more ▼]

A new rotation sensor is developed and tested for the next generation of Ariane space launchers. It aimed at measuring accurately the angular position of an admission valve (target sensitivity of 0.01°) from cryogenic (4K) to room temperature without recalibration. The measurement has to be done contactless and through pipe walls. Innovative electromagnetic application, cryogenic design and data treatment allows reaching the specifications. [less ▲]

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See detailPrecisely controlled mesoporous films to assess the role of architecture in Li‐ion batteries
Krins, Natacha ULg; Buonsanti, Raffaella; Shukla, Alpesh K. et al

Poster (2012)

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See detailPrecisely controlled mesoporous films to assess the role of architecture in nanocrystal-.based electrodes for Li-ion batteries
Krins, Natacha ULg; Buonsanti, Raffaella; Shukla, Alpesh K. et al

Poster (2013, March 04)

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See detailPrécision de l'estimation de l'âge des chevaux par l'examen des dents: résultats d'une étude sur des juments de Trait belge
Nicks, Baudouin ULg; Delfontaine, B.; Claveau, C. et al

in Annales de Médecine Vétérinaire (2007), 151(1), 6-14

The aim of this study was to assess the accuracy of judging age from teeth, with standard aging guides, of mares from 2 to 20 years old registered in the Belgian draft horse stud-book. The replacement of ... [more ▼]

The aim of this study was to assess the accuracy of judging age from teeth, with standard aging guides, of mares from 2 to 20 years old registered in the Belgian draft horse stud-book. The replacement of the deciduous incisors by permanent teeth occurred when expected as the disappearance of the infundibulum on the permanent lower intermediate incisors. The disappearance of the infundibulum was however observed until 16 months earlier than expected on the central incisors and until 18 months later on the corner incisors with 64 % and 50 % of the concerned mares respectively. The modifications of the shape of the occlusal tables from oval to round occurred from 1 to 4 years earlier than expected. The risk to attribute an older age than the true age during the so called round period is lower when taking into account the disappearance of the cup cement leaving only an enamel spot on the occlusal table surface. The modifications of the shape of the incisor tables from round to triangular and to biangular was also observed earlier than expected but only with the central and intermediate incisors, not with the corner incisors. The measurement on photographs of the profile angle of the corner incisors confirmed that this angle decreases with age from about 134 degrees at about 5 years to about 72 degrees at 20 years. Statistical analyses of the differences between real ages and those estimated on pictures by a college of three experts, show that ageing horses from their dentition is more accurate for animals of 8 years old or less, than for older ones. For those animals, the overestimation was about 10 % of the real age. [less ▲]

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See detailPrecision and Accuracy of Asteroseismology Applied to sdB stars Using the Forward Modeling Method
Charpinet, Stéphane; Van Grootel, Valérie ULg; Brassard, Pierre et al

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

Detailed seismic studies of hot B subdwarf (sdB) stars using the forward modeling approach provide measurements of their fundamental parameters at very interesting precisions. For instance, masses, radii ... [more ▼]

Detailed seismic studies of hot B subdwarf (sdB) stars using the forward modeling approach provide measurements of their fundamental parameters at very interesting precisions. For instance, masses, radii, and log g values derived this way are typically claimed at ∼ 1 − 2%, ∼ 0.5%, and ∼ 0.1 % precision, respectively. However, this method relies on still imperfect stellar models that contains various uncertainties associated with their inner structure and the underlying microphysics. A signature of these imperfections is the inability of current best-fit seismic models to reproduce all the observed oscillation frequencies at the precision of the observations. Therefore, the question of the accuracy (as opposed to the precision) of the derived parameters obtained from this approach is legitimate. Here, we revisit the question of precision and accuracy based on new, third generation, complete static models of sdB stars developed for asteroseismology and applied to the case of the eclipsing system PG 1336-018. This allows us to evaluate the reliability of the method and quantify the impact of various uncertainties in the stellar models on the derived stellar parameters. Finally, we discuss the intrinsic potential of asteroseismology for precise measurements of stellar parameters and show that we are far from having fully exploited this technique in terms of precision that can, in principle, be achieved. [less ▲]

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See detailPrecision and practicability: on the definition of the Devonian-Carboniferous Boundary.
Paproth, E; Streel, Maurice ULg

in Courier Forschungsinstitut Senckenberg (1984), 67

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See detailPrecision Asteroseismology of the Pulsating White Dwarf GD 1212 Using a Two-wheel-controlled Kepler Spacecraft
Hermes, J.J.; Charpinet, Stéphane; Barclay, Thomas et al

in Astrophysical Journal (2014), 789

We present a preliminary analysis of the cool pulsating white dwarf (WD) GD 1212, enabled by more than 11.5 days of space-based photometry obtained during an engineering test of the two-reaction-wheel ... [more ▼]

We present a preliminary analysis of the cool pulsating white dwarf (WD) GD 1212, enabled by more than 11.5 days of space-based photometry obtained during an engineering test of the two-reaction-wheel-controlled Kepler spacecraft. We detect at least 19 independent pulsation modes, ranging from 828.2-1220.8 s, and at least 17 nonlinear combination frequencies of those independent pulsations. Our longest uninterrupted light curve, 9.0 days in length, evidences coherent difference frequencies at periods inaccessible from the ground, up to 14.5 hr, the longest-period signals ever detected in a pulsating WD. These results mark some of the first science to come from a two-wheel-controlled Kepler spacecraft, proving the capability for unprecedented discoveries afforded by extending Kepler observations to the ecliptic. [less ▲]

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See detailUne précision constitutionnelle du domaine d'application de la revalorisation des récompenses? Note sous C.const. 16 septembre 2010
Laruelle, Julie ULg

in Revue de Jurisprudence de Liège, Mons et Bruxelles (2011)

Detailed reference viewed: 19 (5 ULg)
See detailLa précision dans les mesures RTK
Wautelet, Gilles ULg

Conference given outside the academic context (2013)

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See detailPrécision de la mesure de hauteurs d'essences feuillues
Rondeux, Jacques ULg; Claustriaux, Jean-Jacques ULg

in Bulletin des Recherches Agronomiques de Gembloux (1983), 18(1), 61-69

La présente étude a pour objet de déterminer la précision de mesures de hauteurs effectuées sur une essence feuillue telle que le hêtre (Fagus sylvatica L.). A partir de mesures réalisées au dendromètre ... [more ▼]

La présente étude a pour objet de déterminer la précision de mesures de hauteurs effectuées sur une essence feuillue telle que le hêtre (Fagus sylvatica L.). A partir de mesures réalisées au dendromètre BLUME-LEISS sur plus de 150 arbres situés dans des peuplements d'allure jardinée, les calculs ont montré que l'on pouvait s'attendre à des écarts individuels atteignant 10 % entre hauteurs estimées et hauteurs mesurées sur arbres abattus. En moyenne, la mesure au dendromètre donnerait lieu à une surestimation d'environ 1 %. Dans l'hypothèse d'une seule mesure effectuée sur un arbre donné, pour un degré de confiance de 95 %, l'intervalle de confiance de l'écart entra la hauteur mesurée au dendromètre et celle mesurée sur arbre abattu, représente en moyenne environ 9 % de la hauteur des arbres. [less ▲]

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See detailPrécision des échantillonnages relatifs à la répartition des arbres par catégories de grosseur.
Grayet, J.-P.; Rondeux, Jacques ULg

Book published by Faculté des Sciences Agronomiques (1980)

The precision of samplings which concern the distribution of trees by girth classes is studied in various forest types (unevenaged and evenaged hardwood stands, evenaged coniferous stands). When sampling ... [more ▼]

The precision of samplings which concern the distribution of trees by girth classes is studied in various forest types (unevenaged and evenaged hardwood stands, evenaged coniferous stands). When sampling intensities of 1 to 10 % (plots of 10 ares), the estimated semi confidence intervals at a 95 % probability level are varying from 10 to 2 %. In coniferous forests (plots of 4 ares) for the same area limits and sampling intensities the semi confidence intervals are varying from 4 to 1 %. [less ▲]

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See detailPrécision des valeurs estimées à l'aide de tarifs de cubage d'arbres
Palm, Rodolphe ULg

in Annales des Sciences Forestières (1983), 40(3), 299-308

La précision du volume estimé d'un ensemble d'arbres à partir d'une équation de cubage dépend essentiellement de la variation résiduelle, de la variation liée à l'équation de cubage, du nombre et de la ... [more ▼]

La précision du volume estimé d'un ensemble d'arbres à partir d'une équation de cubage dépend essentiellement de la variation résiduelle, de la variation liée à l'équation de cubage, du nombre et de la répartition en catégories de grosseurs des arbres à cuber. L'importance relative de ces différents facteurs a été étudiée, d'une part, en fonction des caractéristiques de l'échantillon utilisé pour la construction du tarif et, d'autre part, en fonction des caractéristiques de l'ensemble d'arbres dont on estime le volume. [less ▲]

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See detailPrecision design of ethylene- and polar-monomer-based copolymers by organometallic-mediated radical polymerization
Kermagoret, Anthony ULg; Debuigne, Antoine ULg; Jérôme, Christine ULg et al

in Nature Chemistry (2014), 6(3), 179-187

The copolymerization of ethylene with polar monomers is a major challenge when it comes to the manufacture of materials with potential for a wide range of commercial applications. In the chemical industry ... [more ▼]

The copolymerization of ethylene with polar monomers is a major challenge when it comes to the manufacture of materials with potential for a wide range of commercial applications. In the chemical industry, free-radical polymerization is used to make a large proportion of such copolymers, but the forcing conditions result in a lack of fine control over the architecture of the products. Herein we introduce a synthetic tool, effective under mild experimental conditions, for the precision design of unprecedented ethylene- and polar-monomer-based copolymers. We demonstrate how an organocobalt species can control the growth of the copolymer chains, their composition and the monomer distribution throughout the chain. By fine tuning the ethylene pressure during polymerization and by exploiting a unique reactive mode of the end of the organometallic chain, novel block-like copolymer structures can be prepared. This highly versatile synthetic platform provides access to a diverse range of polymer materials. [less ▲]

Detailed reference viewed: 91 (25 ULg)