Last 7 days     Results 1361-1380 of 69125.   64 65 66 67 68 69 70 71 72 73 74   Le projet « Pratiques et stratégies alimentaires dans l'Antiquité tardive »Marganne, Marie-Hélène Conference (2017, July 28)Detailed reference viewed: 27 (4 ULiège) Écrire de “Guiron” en Flandre à la fin du Moyen ÂgeVeneziale, Marco Conference (2017, July 28)Detailed reference viewed: 16 (0 ULiège) Occupational social and mental stimulation and cognitive decline with advancing ageGrotz, Catherine ; Meillon, Céline; Amieva, Hélène et alin Age and Ageing (2017)Detailed reference viewed: 30 (1 ULiège) Is supercritical fluid chromatography hyphenated to massspectrometry suitable for the quality control of vitamin D3 oilyformulations?Andri, Bertyl ; Dispas, Amandine ; Klinkenberg, Régis et alin Journal of Chromatography. A (2017), 1515Nowadays, many efforts are devoted to improve analytical methods regarding efficiency, analysis timeand greenness. In this context, Supercritical Fluid Chromatography (SFC) is often regarded as a ... [more ▼]Nowadays, many efforts are devoted to improve analytical methods regarding efficiency, analysis timeand greenness. In this context, Supercritical Fluid Chromatography (SFC) is often regarded as a goodalternative over Normal Phase Liquid Chromatography (NPLC). Indeed, modern SFC separations arefast, efficient with suitable quantitative performances. Moreover, the hyphenation of SFC to mass spec-trometry (MS) provides additional gains in specificity and sensitivity. The present work aims at thedetermination of vitamin D3 by SFC-MS for routine Quality Control (QC) of medicines specifically. Basedon the chromatographic parameters previously defined in SFC-UV by Design of Experiments (DoE) andDesign Space methodology, the method was adapted to work under isopycnic conditions ensuring a base-line separation of the compounds. Afterwards, the response provided by the MS detector was optimizedby means of DoE methodology associated to desirability functions. Using these optimal MS parameters,quantitative performances of the SFC-MS method were challenged by means of total error approachmethod validation. The resulting accuracy profile demonstrated the full validity of the SFC-MS method. It was indeed possible to meet the specification established by the European Medicines Agency (EMA) (i.e. 95.0 − 105.0% of the API content) for a dosing range corresponding to at least 70.0-130.0% of theAPI content. These results highlight the possibility to use SFC-MS for the QC of medicine and obviouslysupport the switch to greener analytical methods. [less ▲]Detailed reference viewed: 23 (6 ULiège) The Prediction-Focused Approach: An opportunity for hydrogeophysical data integration and interpretation in the critical zoneHermans, Thomas ; Nguyen, Frédéric ; Klepikova, Maria et alPoster (2017, July 27)Two important challenges remain in hydrogeophysics: the inversion of geophysical data and their integration in quantitative subsurface models. Classical regularized inversion approaches suffer from ... [more ▼]Two important challenges remain in hydrogeophysics: the inversion of geophysical data and their integration in quantitative subsurface models. Classical regularized inversion approaches suffer from spatially varying resolution and yield geologically unrealistic solutions, making their utilization for model calibration less consistent. Advanced techniques such as coupled inversion allow for a direct integration of geophysical data; but, they are difficult to apply in complex cases and remain computationally demanding to estimate uncertainty. We investigated a prediction-focused approach (PFA) to directly estimate subsurface physical properties relevant in the critical zone from geophysical data, circumventing the need for classic inversions. In PFA, we seek a direct relationship between the data and the subsurface variables we want to predict (the forecast). This relationship is obtained through a prior set of subsurface models for which both data and forecast are computed. A direct relationship can often be derived through dimension reduction techniques (Figure 1). For hydrogeophysical inversion, the considered forecast variable is the subsurface variable, such as the salinity or saturation for example. An ensemble of possible solutions is generated, allowing uncertainty quantification. For data integration, the forecast variable is the prediction we want to make with our subsurface models, such as the concentration of contaminant in a drinking water production well. Geophysical and hydrological data are combined to derive a direct relationship between data and forecast. We illustrate the methodology to predict the energy recovered in an ATES system considering the uncertainty related to spatial heterogeneity. With a global sensitivity analysis, we identify sensitive parameters for heat storage prediction and validate the use of a short term heat tracing experiment to generate informative data. We illustrate how PFA can be used to successfully derive the distribution of temperature in the aquifer from ERT during the heat tracing experiment. Then, we successfully integrate the geophysical data to predict heat storage in the aquifer using PFA. The result is a full quantification of the posterior distribution of the prediction conditioned to observed data in a relatively limited time budget. [less ▲]Detailed reference viewed: 35 (7 ULiège) Deep imaging search for planets forming in the TW Hya protoplanetary disk with the Keck/NIRC2 vortex coronagraphRuane, G.; Mawet, D.; Kastner, J. et alin Astronomical Journal (The) (2017), 154Distinct gap features in the nearest protoplanetary disk, TW Hya (distance of 59.5$\pm$0.9 pc), may be signposts of ongoing planet formation. We performed long-exposure thermal infrared coronagraphic ... [more ▼]Distinct gap features in the nearest protoplanetary disk, TW Hya (distance of 59.5$\pm$0.9 pc), may be signposts of ongoing planet formation. We performed long-exposure thermal infrared coronagraphic imaging observations to search for accreting planets especially within dust gaps previously detected in scattered light and submm-wave thermal emission. Three nights of observations with the Keck/NIRC2 vortex coronagraph in $L^\prime$ (3.4-4.1$\mu$m) did not reveal any statistically significant point sources. We thereby set strict upper limits on the masses of non-accreting planets. In the four most prominent disk gaps at 24, 41, 47, and 88 au, we obtain upper mass limits of 1.6-2.3, 1.1-1.6, 1.1-1.5, and 1.0-1.2 Jupiter masses ($M_J$) assuming an age range of 7-10 Myr for TW Hya. These limits correspond to the contrast at 95\% completeness (true positive fraction of 0.95) with a 1\% chance of a false positive within $1^{\prime\prime}$ of the star. We also approximate an upper limit on the product of planet mass and planetary accretion rate of $M_p\dot{M}\lesssim10^{-8} M_J^2/yr$ implying that any putative $\sim0.1 M_J$ planet, which could be responsible for opening the 24 au gap, is presently accreting at rates insufficient to build up a Jupiter mass within TW Hya's pre-main sequence lifetime. [less ▲]Detailed reference viewed: 21 (5 ULiège) Mapping the dependency of crops on pollinators in BelgiumJacquemin, Floriane ; Violle, Cyrille; Rasmont, Pierre et alin One Ecosystem (2017)Detailed reference viewed: 27 (2 ULiège) Building flow and transport models with electrical resistivity tomography dataGottschalk, Ian; Hermans, Thomas ; Knight, Rosemary et alPoster (2017, July 26)Aquifer recharge and recovery (ARR) is the process of enhancing natural groundwater resources and recovering water for later use by constructing engineered conveyances. Insufficient understanding of ... [more ▼]Aquifer recharge and recovery (ARR) is the process of enhancing natural groundwater resources and recovering water for later use by constructing engineered conveyances. Insufficient understanding of lithological heterogeneity at ARR sites often hinders attempts to predict where and how quickly infiltrating water will flow in the subsurface, which can adversely affect the quality and quantity of available water in the ARR site. In this study, we explored the use of electrical resistivity tomography (ERT) to assist in characterizing lithological heterogeneity at an ARR site, so as to incorporate it into a flow and contaminant transport model. In this case, we had non-collocated well core log data and ERT data from a full-scale ARR basin. We compared three independent methods for producing conditional lithology-resistivity probability distributions: 1) a search template to relate the nearest logged well lithologies with ERT resistivity panels, given search criteria; 2) a maximum likelihood estimation (MLE) to match bimodal normal distributions to the histogram of each ERT line; and 3) variogram-based lithology indicator simulations constrained to well data. Each approach leverages Bayes’ Rule to estimate lithology probability given electrical resistivity. The simplest approach (method 1) yields an erroneous conditional probability function where sand dominates the conditional probability at nearly all resistivities, due in part to the strong presence of sand in the wells nearest the ERT lines. The approaches using MLE and lithology simulations (methods 2 and 3) produce similar, more realistic lithofacies probability functions. The range of resistivities where clay and sand overlap differs between methods 2 and 3: ranging between 100 and 200 ohm-m for method 2, and between 30 and 50 ohm-m for the method 3. These differences affect the posterior lithology distributions in multiple point geostatistical (MPS) simulations, and in turn, predictions of flow from models which integrate these results. To test the models, we can compare measured breakthrough times of recharged water at the site to groundwater flow simulation results using the lithofacies models created by each method. The methods described here can inform the integration of non-collocated geophysical data into a variety of applications. [less ▲]Detailed reference viewed: 43 (3 ULiège) Symposium: Work, retirement and health. Presentation: "Retirement and Cognitive Functioning: A Tricky Association"Grotz, Catherine ; Adam, Stéphane Conference (2017, July 26)Detailed reference viewed: 25 (2 ULiège) Evaluating model simulations of 20th century sea-level rise. Part 1: Global mean sea-level changeSlangen, A.; Meyssignac, B.; Agosta, Cécile et alin Journal of Climate (2017)Sea-level change is one of the major consequences of climate change and is projected to affect coastal communities around the world. Here, we compare Global Mean Sea-Level (GMSL) change estimated by 12 ... [more ▼]Sea-level change is one of the major consequences of climate change and is projected to affect coastal communities around the world. Here, we compare Global Mean Sea-Level (GMSL) change estimated by 12 climate models from the 5th phase of the World Climate Research Programme’s Climate Model Intercomparison Project (CMIP5) to observational estimates for the period 1900-2015. We analyse observed and simulated individual contributions to GMSL change (thermal expansion, glacier mass change, ice sheet mass change, landwater storage change) and compare the summed simulated contributions to observed GMSL change over the period 1900-2007 using tide gauge reconstructions, and over the period 1993-2015 using satellite altimetry estimates. The model-simulated contributions allow us to explain 50 ± 30% (uncertainties 1.65σ unless indicated otherwise) of the mean observed change from 1901-1920 to 1988-2007. Based on attributable biases between observations and models, we propose to add a number of corrections, which result in an improved explanation of 75 ± 38% of the observed change. For the satellite era (1993-1997 to 2011-2015) we find an improved budget closure of 102 ± 33% (105 ± 35% when including the proposed bias corrections). Simulated decadal trends over the 20th century increase, both in the thermal expansion and the combined mass contributions (glaciers, ice sheets and landwater storage). The mass components explain the majority of sea-level rise over the 20th century, but the thermal expansion has increasingly contributed to sea-level rise, starting from 1910 onwards and in 2015 accounting for 46% of the total simulated sea-level change. [less ▲]Detailed reference viewed: 33 (2 ULiège) A panmictic Amazonian world? : Bryophytes testifyLedent, Alice Poster (2017, July 25)Understanding connectivity over different spatial and temporal scales is fundamental for biodiversity conservation and management. The Amazonian rainforest, one of the most diverse biodiversity hotspots ... [more ▼]Understanding connectivity over different spatial and temporal scales is fundamental for biodiversity conservation and management. The Amazonian rainforest, one of the most diverse biodiversity hotspots, has experienced dramatic range contractions and expansions due to Pleistocene climate oscillations, and its human-induced fragmentation has accelerated at an unparalleled pace in the course of the Anthropocene. In this context, epiphytes, with their relatively short life-cycles, offer an ideal model to investigate the impact of past and present fragmentation on patterns of genetic structure and diversity. Due to the necessity to switch from one host tree to another, or from one leaf to another, epiphytic bryophytes typically exhibit high dispersal syndromes. In line with such high dispersal capacities, recent metacommunity analyses have arisen the intriguing question that Amazonian epiphytic bryophyte communities are homogeneous across very large spatial scales, ultimately raising the notion that they might behave as a basin-wide panmictic population. Here, we implement fine-scale population genetic analyses to address the following questions:(i) Do Amazonian epiphytes exhibit population structure at regional (< 500 km) scale; (ii) If the hypothesis of a panmictic population is rejected, (iia) at which spatial scale does genetic structuring occur, and (iib) do neutral (isolation-by-distance) or ecological (isolation-by-ecology) processes shape patterns of genetic variation? We sampled exemplars of 15 epiphytic bryophyte species from two ecologically contrasted forest types (lowland rainforest and white-sand forest) in a 50,000 km2 area in the middle Rio Negro. Genome-wide genetic data were produced using Genotyping By Sequencing. To circumvent severe taxonomic issues in challenging groups, which, like the Calymperaceae, are dominant in the epiphytic flora, we first implemented species delimitation analyses to sort-out specimens taxonomically. We then described the fine-scale genetic structure of each species and performed isolation-by-distance analyses to detect significant spatial genetic structuring. We finally determined whether isolation-by-distance or ecological filtering contribute to the observed patterns of genetic variation. The study will provide key information on the populations dynamics of highly mobile species integral to the iconic Amazonian forest, which may further be employed to refine future conservation policies in the face of accelerating climate change and anthropogenic-mediated deforestation. [less ▲]Detailed reference viewed: 25 (4 ULiège) The effect of initial water distribution and spatial resolution on the interpretation of ERT monitoring of water infiltrationDumont, Gaël ; Pilawski, Tamara ; Robert, Tanguy et alPoster (2017, July 25)A better understanding of the water balance of a landfill is crucial for its management, as the waste water content is the main factor influencing the biodegradation process of organic waste. In order to ... [more ▼]A better understanding of the water balance of a landfill is crucial for its management, as the waste water content is the main factor influencing the biodegradation process of organic waste. In order to investigate the ability of long electrical resistivity tomography (ERT) profiles to detect zones of high infiltration in a landfill cover layer, low resolution time lapse data were acquired during a rainfall event. Working at low resolution allows to cover large field areas but with the drawback of limiting quantitative interpretation. In this contribution, we use synthetic modeling to quantify the effect of the following issues commonly encountered when dealing with field scale ERT data: (i) the effect of low resolution on electrical resistivity changes interpretation, (ii) the effect of the original heterogeneous resistivity distribution on the observed relative resistivity changes, (iii) the need for temperature and pore fluid conductivity data in order to compute water content and absolute changes of water content, and (iv) the interpretation error commonly made while neglecting the dilution effect during fresh water infiltration. Firstly, due to the lack of spatial resolution, the regularized inversion process yields a smoothed distribution of resistivity changes that fail to detect small infiltration zones and yields an overestimation of the infiltration depth and an underestimation of the infiltrated volume in large infiltration areas. Secondly, the analysis of relative changes, as commonly used in literature, is not adequate when the background water content is highly heterogeneous. In such a case, relative changes reflect both the initial water content distribution and the observed changes. Thirdly, the computation of absolute water content changes better reflects the infiltration pattern, but requires spatially distributed temperature and pore fluid conductivity input data. Lastly, the dilution effect, if not considered, leads to an underestimation of the infiltrated volume. Taking into account these elements, we extracted the maximum amount of information from our field data without over-interpreting the results. This allowed the detection of larger infiltration areas possibly responsible for a large part of the annual water infiltration and landfill gas loss. [less ▲]Detailed reference viewed: 24 (3 ULiège) Shape and spin determination of Barbarian asteroidsDevogele, Maxime ; Tanga, P.; Bendjoya, P. et alin Astronomy and Astrophysics (2017)The so-called Barbarian asteroids share peculiar, but common polarimetric properties, probably related to both their shape and composition. They are named after (234) Barbara, the first on which such ... [more ▼]The so-called Barbarian asteroids share peculiar, but common polarimetric properties, probably related to both their shape and composition. They are named after (234) Barbara, the first on which such properties were identified. As has been suggested, large scale topographic features could play a role in the polarimetric response, if the shapes of Barbarians are particularly irregular and present a variety of scattering/incidence angles. This idea is supported by the shape of (234) Barbara, that appears to be deeply excavated by wide concave areas revealed by photometry and stellar occultations. Aims. With these motivations, we started an observation campaign to characterise the shape and rotation properties of Small Main- Belt Asteroid Spectroscopic Survey (SMASS) type L and Ld asteroids. As many of them show long rotation periods, we activated a worldwide network of observers to obtain a dense temporal coverage. Methods. We used light-curve inversion technique in order to determine the sidereal rotation periods of 15 asteroids and the con- vergence to a stable shape and pole coordinates for 8 of them. By using available data from occultations, we are able to scale some shapes to an absolute size. We also study the rotation periods of our sample looking for confirmation of the suspected abundance of asteroids with long rotation periods. Results. Our results show that the shape models of our sample do not seem to have peculiar properties with respect to asteroids with similar size, while an excess of slow rotators is most probably confirmed. [less ▲]Detailed reference viewed: 38 (1 ULiège) Modèles de porosité pour les inondations urbainesDewals, Benjamin ; Bruwier, Martin ; El Saeid Mustafa, Ahmed Mohamed et alScientific conference (2017, July 25)Detailed reference viewed: 44 (9 ULiège) HARMONIC BALANCE COMPUTATION OF THE NONLINEAR FREQUENCY RESPONSE OF A THIN PLATELee, Jongsuh ; Kerschen, Gaëtan ; Detroux, Thibaut Conference (2017, July 24)The harmonic balance method (HBM) is used to investigate the dynamical behavior of the geometrical nonlinear plate. The middle plane displacements are included in the plate in which the equations of ... [more ▼]The harmonic balance method (HBM) is used to investigate the dynamical behavior of the geometrical nonlinear plate. The middle plane displacements are included in the plate in which the equations of motion are developed by the principle virtual work. Moreover, the nonlinear frequency response curves, or NFRCs, are obtained by a continuation method. [less ▲]Detailed reference viewed: 44 (4 ULiège) Comprehensive Ion Mobility Calibration Strategies based on Synthetic PolymersHaler, Jean ; Kune, Christopher ; Chirot, Fabien et alConference (2017, July 24)Detailed reference viewed: 41 (6 ULiège) Deep investigation of ion mobility mass spectrometry data and computational chemistry support to prevent chemical and physical chemistry misinterpretationKune, Christopher ; Far, Johann ; Haler, Jean et alConference (2017, July 24)Detailed reference viewed: 33 (7 ULiège) Self-assembly processes of superparamagnetic colloids in a quasi-two-dimensional systemRojas, Nicolas; Darras, Alexis ; Lumay, Geoffroy in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2017), 96(1), 012608Superparamagnetic colloids gather depending on the magnitude of the magnetic field applied, forming chains and ribbons in a quasi-two-dimensional chamber. The results presented in this work are in good ... [more ▼]Superparamagnetic colloids gather depending on the magnitude of the magnetic field applied, forming chains and ribbons in a quasi-two-dimensional chamber. The results presented in this work are in good agreement with recent experimental multistable data for the mean length of the aggregates in thermodynamic equilibrium. [less ▲]Detailed reference viewed: 37 (2 ULiège) Dual-specificity-phosphatase 3 (DUSP3) deletion promotes liver inflammation and high fat diet-induced hepatocellular carcinomaJacques, Sophie ; Arjomand, Arash ; Vandereyken, Maud et alPoster (2017, July 24)Overweight and obesity are considered as risk factors for hepatocellular carcinoma (HCC) development. The mechanisms by which obesity promotes liver inflammation are however poorly understood. We recently ... [more ▼]Overweight and obesity are considered as risk factors for hepatocellular carcinoma (HCC) development. The mechanisms by which obesity promotes liver inflammation are however poorly understood. We recently generated a full DUSP3 knockout (KO) mouse. The obtained mice were born normal with no spontaneous phenotype. However, while aging, DUSP3-KO mice became obese and developed hepatosteatosis. The phenotype was exacerbated under high fat diet (HFD). Furthermore, when treated with diethylnitrosamine (DEN) procarcinogen, DUSP3-KO mice developed HCC faster than WT littermates. The combination of DEN with HFD accelerated the onset of HCC development in these mice compared to WT mice. This was associated with increased systemic levels of several metabolites and with hyperphosphorylation of the insulin-like growth factor receptor I. [less ▲]Detailed reference viewed: 23 (4 ULiège) Functional and structural characterisation of the Arabidopsis thaliana HMA4 proteinLekeux, Gilles ; Laurent, Clémentine; Xiao, Zhiguang et alPoster (2017, July 24)Detailed reference viewed: 27 (5 ULiège)