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See detailDiurnal cycle and multi-decadal trend of formaldehyde in the remote atmosphere near 46° N
Franco, Bruno ULg; Marais, Eloise A.; Bovy, Benoît ULg et al

in Atmospheric Chemistry and Physics (2016), 16

Only very few long-term records of formaldehyde (HCHO) exist that are suitable for trend analysis. Furthermore, many uncertainties remain as to its diurnal cycle, representing a large short-term ... [more ▼]

Only very few long-term records of formaldehyde (HCHO) exist that are suitable for trend analysis. Furthermore, many uncertainties remain as to its diurnal cycle, representing a large short-term variability superimposed on seasonal and inter-annual variations that should be accounted for when comparing ground-based observations to e.g., model results. In this study, we derive a multi-decadal time series (January 1988 – June 2015) of HCHO total columns from ground-based high-resolution Fourier transform infrared (FTIR) solar spectra recorded at the high-altitude station of Jungfraujoch (Swiss Alps, 46.5° N, 8.0° E, 3580 m a.s.l.), allowing for the characterization of the mid-latitudinal atmosphere for background conditions. First we investigate the HCHO diurnal variation, peaking around noontime and mainly driven by the intra-day insolation modulation and methane (CH4) oxidation. We also characterize quantitatively the diurnal cycles by adjusting a parametric model to the observations, which links the daytime to the HCHO columns according to the monthly intra-day regimes. It is then employed to scale all the individual FTIR measurements on a given daytime in order to remove the effect of the intra-day modulation for improving the trend determination and the comparison with HCHO columns simulated by the state-of-the-art chemical transport model GEOS-Chem v9-02. Such a parametric model will be useful to scale the Jungfraujoch HCHO columns on satellite overpass times in the framework of future calibration/validation efforts of space borne sensors. GEOS-Chem sensitivity tests suggest then that the seasonal and inter-annual HCHO column variations above Jungfraujoch are predominantly led by the atmospheric CH4 oxidation, with a maximum contribution of 25 % from the anthropogenic non-methane volatile organic compound precursors during wintertime. Finally, trend analysis of the so-scaled 27-year FTIR time series reveals a long-term evolution of the HCHO columns in the remote troposphere to be related with the atmospheric CH4 fluctuations and the short-term OH variability: +2.9 %/yr between 1988 and 1995, -3.7 %/yr over 1996-2002 and +0.8/% yr from 2003 onwards. [less ▲]

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See detailDiurnal Rhythmicity in the Pattern of Mrnas in the Leaves of Sinapis Alba
Cremer, Frédéric ULg; Dommes, Jacques ULg; Van de Walle, Claude ULg et al

in Plant Physiology (1990), 94(4), 1590-1597

Previous studies have shown that certain specific leaf mRNAs exhibit a diurnal rhythmicity in their quantity in higher plants. To determine whether this situation is restricted to a few mRNAs, or affects ... [more ▼]

Previous studies have shown that certain specific leaf mRNAs exhibit a diurnal rhythmicity in their quantity in higher plants. To determine whether this situation is restricted to a few mRNAs, or affects a large number, we have used in vitro translation and two-dimensional polyacrylamide gel electrophoresis to analyze the mRNA complement in leaves of Sinapis alba at different times during an 8-hour/16-hour day/night cycle. A method for the visual analysis of two-dimensional polyacrylamide gel electrophoresis was also developed. This method selected, at each sampling time, spots that were significant. It then selected, between two sampling times, intensity changes that were significant at the 0.02 confidence level. During a day/night cycle, complex rhythmic changes affected about 10% of the mRNAs. Nineteen different rhythm patterns were found. These 19 patterns fell into four main classes: mRNAs that increase during the light period and decrease during the dark, mRNAs that increase and then decrease during the light period, mRNAs that decrease during the light period and increase during the dark period, and mRNAs that increase and then decrease during the dark period. [less ▲]

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See detailDiurnal thermosphere scale height from MEX/SPICAM grazing limb data
Stiepen, Arnaud ULg; Gérard, Jean-Claude ULg; Bougher, S et al

Conference (2014, July 01)

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See detailThe diurnal variation of NO, N(D-2), and ions in the thermosphere - A comparison of satellite measurements to a model
Rusch, D. W.; Gérard, Jean-Claude ULg; Fesen, C. G.

in Journal of Geophysical Research (1991), 96

A data base of parameters important to understanding the diurnal variation of odd-nitrogen and ions in the thermosphere near equinox, at low latitudes, and for quiet geomagnetic conditions is presented ... [more ▼]

A data base of parameters important to understanding the diurnal variation of odd-nitrogen and ions in the thermosphere near equinox, at low latitudes, and for quiet geomagnetic conditions is presented. The data base includes profiles of the odd-nitrogen species NO and N(D-2), the ions NO(+), O2(+), O(+), N2(+), and N(+); the total ion density; O and N2; and the neutral, ion, and electron temperatures. The measured time-dependent variations of NO, N(D-2), O2(+), and NO(+) compare favorably to the results of a time-dependent, photochemical, diffusion model for odd-nitrogen and ion chemistry. In particular, the model reproduces the rapid increase in NO density in the morning hours, the midafternoon maximum, and the late afternoon decrease. The model also reproduces the measured absolute densities for NO to within 20 percent over most of the diurnal cycle but falls below the measured density by as much as a factor of two in the late afternoon. [less ▲]

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See detailDiurnal variations of hormonal secretion, alertness and cognition in extreme chronotypes under different lighting conditions.
Maierova, L.; Borisuit, A.; Scartezzini, L et al

in Scientific Reports (2016)

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See detailDiurnal variations of plasma FSH, LH, and testosterone in male ring doves kept under different photoperiods.
Balthazart, Jacques ULg; Reboulleau, C.; Cheng, M. F.

in General and Comparative Endocrinology (1981), 44(2), 202-6

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See detailDiurnal variations of plasma gonadotrophins in male domestic ducks during the sexual cycle.
Balthazart, Jacques ULg; Hendrick, J. C.; Deviche, P.

in General and Comparative Endocrinology (1977), 32(4), 376-89

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See detailDiurnal variations of sexual receptivity in the female Japanese quail (Coturnix coturnix japonica).
Delville, Y.; Sulon, J.; Balthazart, Jacques ULg

in Hormones and Behavior (1986), 20(1), 13-33

A series of experiments was performed to study the changes during the day of female receptivity in Japanese quail. In each experiment, the frequency of squatting and the percentage of male approaches ... [more ▼]

A series of experiments was performed to study the changes during the day of female receptivity in Japanese quail. In each experiment, the frequency of squatting and the percentage of male approaches which were followed by squatting increased at the end of the day, approximately 11 to 13 hr after lights on (in a photoperiod of 16L:8D). In some cases this increased receptivity was associated with a significant decrease of the long-avoid frequency. Analyses are presented which demonstrate that the increased receptivity at the end of the day is not directly caused by the oviposition and does not result directly from changes in the behavior of the male stimuli. This is strongly supported by the observation that the increase in receptivity was observed at the same time after lights on (but different clock times) in two groups of females which were raised in two different photoperiods shifted by 6 hr and tested with the same group of males raised in one of the two photoperiods. The increase in receptivity coincides with an increase in plasma estradiol and progesterone. Considering that this behavior is suppressed by ovariectomy, it is argued that the daily changes in receptivity could be controlled by the hormonal changes associated with the ovulatory cycle. [less ▲]

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See detailDIVA Graphical User Interface
Troupin, Charles ULg; Sirjacobs, Damien ULg; Beckers, Jean-Marie ULg

Conference (2006, November 13)

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See detailDIVA-4.2.1: presentation of the new features
Troupin, Charles ULg; Machín, Francisco; Ouberdous, Mohamed ULg et al

Poster (2008, April 03)

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See detailDIVA: a Data Analysis Software with Generalized-Cross Validation and Quality Control
Troupin, Charles ULg; Rixen, Michel; Sirjacobs, Damien ULg et al

Poster (2007, May 19)

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See detailDIVA: new features
Beckers, Jean-Marie ULg; Alvera Azcarate, Aïda ULg; Barth, Alexander ULg et al

Scientific conference (2009, October 23)

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See detaildivand-1.0: n-dimensional variational data analysis for ocean observations
Barth, Alexander ULg; Beckers, Jean-Marie ULg; Troupin, Charles ULg et al

in Geoscientific Model Development (2014), 7

A tool for multidimensional variational analysis (divand) is presented. It allows the interpolation and analysis of observations on curvilinear orthogonal grids in an arbitrary high dimensional space by ... [more ▼]

A tool for multidimensional variational analysis (divand) is presented. It allows the interpolation and analysis of observations on curvilinear orthogonal grids in an arbitrary high dimensional space by minimizing a cost function. This cost function penalizes the deviation from the observations, the deviation from a first guess and abruptly varying fields based on a given correlation length (potentially varying in space and time). Additional constraints can be added to this cost function such as an advection constraint which forces the analysed field to align with the ocean current. The method decouples naturally disconnected areas based on topography and topology. This is useful in oceanography where disconnected water masses often have different physical properties. Individual elements of the a priori and a posteriori error covariance matrix can also be computed, in particular expected error variances of the analysis. A multidimensional approach (as opposed to stacking 2-dimensional analysis) has the benefit of providing a smooth analysis in all dimensions, although the computational cost is increased. Primal (problem solved in the grid space) and dual formulations (problem solved in the observational space) are implemented using either direct solvers (based on Cholesky factorization) or iterative solvers (conjugate gradient method). In most applications the primal formulation with the direct solver is the fastest, especially if an a posteriori error estimate is needed. However, for correlated observation errors the dual formulation with an iterative solver is more efficient. The method is tested by using pseudo observations from a global model. The distribution of the observations is based on the position of the ARGO floats. The benefit of the 3-dimensional analysis (longitude, latitude and time) compared to 2-dimensional analysis (longitude and latitude) and the role of the advection constraint are highlighted. The tool divand is free software, and is distributed under the terms of the GPL license (http://modb.oce.ulg.ac.be/mediawiki/index.php/divand). [less ▲]

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See detailDivergence of function and regulation of class B floral organ identity genes.
Samach, A.; Kohalmi, S. E.; Motte, Patrick ULg et al

in Plant Cell (1997), 9(4), 559-70

Regulatory mechanisms controlling basic aspects of floral morphogenesis seem to be highly conserved among plant species. The class B organ identity genes, which are required to establish the identity of ... [more ▼]

Regulatory mechanisms controlling basic aspects of floral morphogenesis seem to be highly conserved among plant species. The class B organ identity genes, which are required to establish the identity of organs in the second (petals) and third (stamens) floral whorls, are a good example of such conservation. This work compares the function of two similar class B genes in the same genetic background. The DEFICIENS (DEF) gene from Antirrhinum, including its promoter, was transformed into Arabidopsis and compared in function and expression with the Arabidopsis class B genes APETALA3 (AP3) and PISTILLATA (PI). The DEF gene was expressed in the second, third, and fourth whorls, as was PI. Functionally, DEF could replace AP3 in making petals and stamens. The DEF gene's AP3-like function and PI-like expression caused transformation of fourth-whorl carpels to stamens. Like AP3, all aspects of DEF function in Arabidopsis required a functional PI protein. Surprisingly, DEF could not replace the AP3 protein in properly maintaining AP3 transcripts (autoregulation). Our data allow us to revise the current model for class B autoregulation and propose a hypothesis for the evolution of class B gene expression in dicotyledonous plants. [less ▲]

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See detailDivergence of wavelet series: A multifractal analysis
Esser, Céline ULg; Jaffard, Stéphane ULg

E-print/Working paper (2017)

We show the relevance of a multifractal-type analysis for pointwise convergence and divergence properties of wavelet series: Depending on the sequence space which the wavelet coefficients sequence belongs ... [more ▼]

We show the relevance of a multifractal-type analysis for pointwise convergence and divergence properties of wavelet series: Depending on the sequence space which the wavelet coefficients sequence belongs to, we obtain deterministic upper bounds for the Hausdorff dimensions of the sets of points where a given rate of divergence occurs, and we show that these bounds are generically optimal, according to several notions of genericity. [less ▲]

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See detailDivergences et convergences des politiques d'intégration dans la Belgique multinationale. Le cas de parcours d'intégration pour les immigrés
Martiniello, Marco ULg; Ilke, Adam

in Revue Européenne des Migrations Internationales (2013), 29(2), 77-93

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See detailDivergences institutionelles et convergences mimétiques
Renard, Hugues ULg; Petit Jean, Maxime

Conference (2012, July)

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See detailDivergences morphologiques et génétiques chez une espèce de demoiselle (Pomacentridae): Pomacentrus coelestis
Frederich, Bruno ULg; Liu, Shang-Yin

Conference (2012, March 30)

La différentiation des populations est l’un des principaux thèmes de la biologie de l’évolution. Mise à part l’étude des variations des patrons de coloration, très peu d’études concernent les divergences ... [more ▼]

La différentiation des populations est l’un des principaux thèmes de la biologie de l’évolution. Mise à part l’étude des variations des patrons de coloration, très peu d’études concernent les divergences morphologiques entre les populations de poissons des récifs coralliens. Dans ce travail, nous avons étudié la différentiation morphologique et génétique entre plusieurs populations de l’espèce de demoiselle, Pomacentrus coelestis Jordan & Starks, 1901, dans le Nord-Ouest de l’océan Pacifique. Cette espèce, inféodée aux récifs coralliens, se nourrit principalement de zooplancton. Elle est particulièrement abondante dans cette région du monde. Les formes des mâchoires buccales (c’est-à-dire la mandibule et le prémaxillaire) ont été étudiées au moyen des méthodes de morphométrie géométrique et la structure génétique des populations a été caractérisée au moyen de cinq microsattelites (POM3, POM2, AC1578, Pom2269 et Pom2416). Différents tests statistiques ont révélé une variation significative de forme entre les populations de P. coelestis pour chacune des deux pièces squelettiques. Les variations de forme de la mandibule et du prémaxillaire apparaissent non-corrélées. Les variations morphologiques de la mandibule accompagne une rupture génétique entre des populations de l’île principale du Japon et les îles d’Okinawa et Taiwan. Cependant, les tests de Mantel et Procrustes n’ont révélé aucune congruence entre les structures génétiques et morphologiques. Des variables géographiques telles que la latitude, la longitude et les distances kilométriques expliquent peu ou pas les variances morphologiques observées. Dans notre discussion, nous illustrons que la plasticité phénotypique serait un mécanisme évolutif potentiel sous-jacent à la différence de formes entre les populations de P. coelestis. Cependant l’hypothèse d’une divergence adaptative ne pourrait cependant pas être exclue vu que nous avons uniquement étudié des marqueurs génétiques neutres (microsattelites). Une approche écomorphologique suggère que des régimes alimentaires différents pourraient être liés aux variations de forme des mâchoires buccales. A titre d’exemple, les individus des populations de l’île principale du Japon ont des mandibules plus massives suggérant des activités de broutage et/ou de morsure plus fréquentes. Inversément, les individus de Taiwan et d’Okinawa arborent un processus ascendant du prémaxillaire proportionellement plus long que les poissons des autres populations. Cette caractéristique, directement liée à l’efficacité de protrusion des mâchoires supérieures, confirmerait un degré de zooplanctonophagie plus élevé chez ces deux populations. [less ▲]

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See detailDivergent biophysical controls of aquatic CO2 and CH4 in the World’s two largest rivers
Borges, Alberto ULg; Abril, G; Darchambeau, François ULg et al

in Scientific Reports (2015), 5

Carbon emissions to the atmosphere from inland waters are globally significant and mainly occur at tropical latitudes. However, processes controlling the intensity of CO2 and CH4 emissions from tropical ... [more ▼]

Carbon emissions to the atmosphere from inland waters are globally significant and mainly occur at tropical latitudes. However, processes controlling the intensity of CO2 and CH4 emissions from tropical inland waters remain poorly understood. Here, we report a data-set of concurrent measurements of the partial pressure of CO2 (pCO2) and dissolved CH4 concentrations in the Amazon (n = 136) and the Congo (n = 280) Rivers. The pCO2 values in the Amazon mainstem were significantly higher than in the Congo, contrasting with CH4 concentrations that were higher in the Congo than in the Amazon. Large-scale patterns in pCO2 across different lowland tropical basins can be apprehended with a relatively simple statistical model related to the extent of wetlands within the basin, showing that, in addition to non-flooded vegetation, wetlands also contribute to CO2 in river channels. On the other hand, dynamics of dissolved CH4 in river channels are less straightforward to predict, and are related to the way hydrology modulates the connectivity between wetlands and river channels. [less ▲]

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See detailDivers problèmes bactériens rencontrés chez les animaux domestiques
Mainil, Jacques ULg; Devriese, L.

Learning material (2002)

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