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See detailLa socialisation professionnelle des facilitateurs de l’ONEm : un processus situé au cœur des interactions avec les demandeurs d’emploi
Beuker, Laura ULiege

Conference (2017, July 04)

Les facilitateurs sont des agents qui travaillent à l’Office National de l’Emploi, organisme responsable de l’assurance chômage en Belgique. Ils sont chargés de procéder au contrôle de la suffisance et du ... [more ▼]

Les facilitateurs sont des agents qui travaillent à l’Office National de l’Emploi, organisme responsable de l’assurance chômage en Belgique. Ils sont chargés de procéder au contrôle de la suffisance et du caractère « actif » de la recherche d’emploi des chômeurs lors d’entretiens individuels. Au cours de ceux-ci, c’est l’indemnisation (les allocations de chômage) qui est en jeu. Pour effectuer ces évaluations, les agents prennent appui sur la réglementation chômage, mais pas seulement. À partir d’observations micro-sociologiques réalisées dans trois bureaux de chômage (BC1, BC2 et BC3), nous montrerons que les facilitateurs font régulièrement face à des cas de conscience et que, pour résoudre ces derniers, ils mobilisent des éléments qui ne se cantonnent pas à la réglementation chômage ou à leur formation initiale. Leur socialisation professionnelle ne se résume ainsi pas à la mise en œuvre d’enseignements préalables, elle se construit dans le cœur même des interactions avec les demandeurs d’emploi, c’est-à-dire dans le travail. [less ▲]

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See detailComparative Proteomics Analysis Provides New Candidates for Zinc Homeostasis Regulation in Arabidopsis
Amini, Sahand ULiege; Arsova, Borjana ULiege; Scheepers, Maxime ULiege et al

Poster (2017, July 03)

Zinc (Zn) is an essential micronutrient for plants and around two billion people are depending on grains and legumes as their main Zn source. On the other hand, this transition metal is toxic for plants ... [more ▼]

Zinc (Zn) is an essential micronutrient for plants and around two billion people are depending on grains and legumes as their main Zn source. On the other hand, this transition metal is toxic for plants at high concentrations in soils. This calls for a better unravelling of Zn homeostasis regulation mechanisms, including sensing and signaling in plants. In order to fulfill this aim, we are testing for novel proteins involved in Zn homeostasis in the model plant Arabidopsis thaliana. First, quantitative proteomics was performed on root and shoot samples obtained upon Zn starvation and re-supply in different spatio-temporal conditions. Inductively coupled plasma atomic emission spectroscopy (ICP-AES) analysis was also performed for those treatments to measure the Zn concentration in tissues. It showed very rapid Zn uptake in root upon re-supply. Moreover, quantitative expression studies of known players of Zn homeostasis confirmed our large-scale proteomic results, although for a few genes lack of correlation between transcript and protein regulation was observed. Using clustering, statistical and gene ontology analyses, we selected candidate genes for further studies. Among more than 5000 detected proteins in roots by shotgun proteomics, 75 genes were selected for targeted analyses. In general, our results show that comparative proteomics study can be useful to reveal new players in the Zn regulatory network in plants, which can lead to new Zn biofortification and phytoremediation strategies. [less ▲]

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See detailBenchmarking the Environmental Impact of Green and Traditional Masonry Wall Constructions
Gauvreau-Lemelin, Corinne; Attia, Shady ULiege

in Brotas, Luisa; Roaf, Susan; Fergus, Nicol (Eds.) Passive low energy architecture design to thrive (2017, July 03)

In Belgium, the most common approach for nearly Zero Energy Buildings is to comply with the locally modified version of the German Passive House (PH) Standard that requires a very low conductivity of ... [more ▼]

In Belgium, the most common approach for nearly Zero Energy Buildings is to comply with the locally modified version of the German Passive House (PH) Standard that requires a very low conductivity of exterior walls. The conventional PH brick constructions are dominated by building materials with high environmental impact including concrete blocks, firebrick and petrochemical insulation materials that produce a great amount of greenhouse gases (GHG). Moreover, there are very few studies that assessed the holistic environmental impact of conventional wall compositions against ecological wall compositions. Therefore, this research compares a traditional Belgian representative wall against a hemp block wall, according to the PH standard. The environmental impact of each wall is quantified through a life cycle assessment. The final results indicate that the hemp wall reinforced with a wood skeleton has a much lower impact on the environment: up to 60% reduction on total primary energy, 72% on climate changes, 93% on eutrophication, 61 % on ozone layer depletion and 74% on acidification. Future work may refine the assessment process. The study provides novel and significant findings that can inform building owners, architects and contractors and encourage them to choose environmentally friendly masonry wall compositions. [less ▲]

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See detailCharacterizing Thiamine Status and Mechanisms of Thiamine Supplementation on Subacute Ruminal Acidosis Attenuation in Dairy Cows
Pan, Xiaohua ULiege

Doctoral thesis (2017)

Dairy cows are often fed high grain diets to maximize milk production in today’s intensive management farms. However, overfeeding high grain diets increases the risk of subacute ruminal acidosis (SARA ... [more ▼]

Dairy cows are often fed high grain diets to maximize milk production in today’s intensive management farms. However, overfeeding high grain diets increases the risk of subacute ruminal acidosis (SARA), which is characterized by prolonged decrease in rumen pH and high levels of lipopolysaccharide (LPS). SARA challenge has been confirmed to severely impair animal health, production performance and farm profitability, and more and more attentions have been paid to prevent the occurrence of SARA in dairy industry worldwide. Our teams’ previous research found that thiamine supplementation relieved SARA in dairy cows, but the modes of action of thiamine in SARA attenuation are still unclear. In this context, this thesis was conducted to increase our understanding of relationships between SARA induction and thiamine, and to explore the mechanisms of thiamine supplementation on SARA attenuation by determining its effects on rumen fermentation, microbiome composition and anti-inflammatory response. Firstly, the first experiment in Chapter III demonstrated that thiamine status in rumen and blood were altered by SARA induction and thiamine deficiency occurred during SARA challenge. Regression analysis proved the ruminal thiamine content was positively related to pH and the concentrations of acetate in the rumen, and negatively correlated to the lactate contents, indicating the altered rumen fermentation would affect thiamine status. Secondly, the mRNA expression of thiamine transporters in ruminal epithelium (Chapter IV) and ruminal bacteria compositions (Chapter V) in SARA and control cows were detected. We found that thiamine concentration was positively correlated with Bacteroides, Ruminococcus 1, Ruminobacter, Pyramidobacter and Fibrobacter, and the decrease in these genera implied SARA challenge altered ruminal thiamine status by inhibiting the growth of thiamine synthesis related bacteria. The positive correlation between ruminal and blood thiamine, and the down-regulation of thiamine transporters’ expression in rumen epithelium indicated the reduced ruminal thiamine synthesis and thiamine absorption by SARA challenge resulted in low blood thiamine content of SARA cows. Thirdly, the effects of thiamine on rumen fermentation (Chapter III), anti-inflammatory response (Chapter IV) and microbiome composition (Chapter V) were evaluated to reveal its mechanisms on SARA attenuation. We found that thiamine supplementation promoted acetate-producing bacteria including Ruminococcus 1, Pyramidobacter, Succinivibrio and Bacteroides, and decreased bacteria positively related to ruminal lactate (Succiniclasticum and Ruminococcaceae NK4A214). Consequently, rumen fermentation was improved by reducing the accumulation of lactate and increasing ruminal pH. In addition, thiamine supplementation alleviated inflammatory response in rumen epithelium by reducing the release of LPS and phosphorylation of NFκB protein, which is conducive to SARA attenuation. In summary, this thesis had increased our understanding of thiamine nutrition in dairy cows, and provided a new control strategy for subacute ruminal acidosis in dairy cows. However, further investigations are needed to deeply understand the relationship between thiamine and SARA induction, such as the isolation and validation of thiamine synthesis bacteria affected by SARA challenge, as well as to figure out metabolic pathways through which SARA induction affects thiamine synthesis in the rumen. Moreover, the impacts of overfeeding high grain diets on intestinal thiamine absorption are still unclear and need to be illuminated in dairy cows. [less ▲]

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See detailOmics insights into rumen ureolytic bacterial community and urea metabolism in dairy cows
Jin, Di ULiege

Doctoral thesis (2017)

Urea has been used in the diets of ruminants as a non-protein nitrogen source. Ureolytic bacteria are key organisms in the rumen producing urease enzymes to catalyze the breakdown of urea to ammonia (NH3 ... [more ▼]

Urea has been used in the diets of ruminants as a non-protein nitrogen source. Ureolytic bacteria are key organisms in the rumen producing urease enzymes to catalyze the breakdown of urea to ammonia (NH3), and the NH3 is used as nitrogen for microbial protein synthesis. In the rumen, hydrolysis of urea to NH3 occurs at a greater rate than NH3 can be utilized by rumen bacteria, and excess ammonia absorbed into blood may be harmful to the animals. Nowadays, little is known about the information of ureolytic microorganisms in the rumen, and the changes that occur in the rumen microbial and host metabolites induced by urea nitrogen have not been fully characterized. ‘Omics’ approaches, such as metagenomics and metabolomics have been applied to analyzing rumen microbial community and nutrients metabolism in dairy cows. The objective of this study is to investigate the rumen predominant ureolytic bacteria community and the mechanisms of urea utilization in ruminants using sequencing and metabolomics approaches. Firstly, an in vitro experiment trying to explore the ruminal ureolytic bacterial community was performed. Urea or acetohydroxamic acid were supplemented into the rumen simulation systems as the stimulator and inhibitor for ureolytic bacteria, respectively. The bacterial 16S rRNA genes were analyzed by Miseq sequencing and used to reveal the ureolytic bacteria by comparing different treatments. We found that urea supplementation significantly increased the proportion of ureC genes. The rumen ureolytic bacteria were abundant in the genera of Pseudomonas, Haemophilus, Neisseria, Streptococcus, Actinomyces, Bacillus and unclassified Succinivibrionaceae. Secondly, an in vivo experiment was taken to investigate differences in ureolytic bacterial composition between the rumen digesta and rumen wall based on ureC gene classification. Six dairy cows with rumen fistula were assigned to a two-period cross-over trial. One group was fed a total mixed ration without urea and the treatment group was fed rations plus 180 g urea per cow per day. Rumen bacterial samples from rumen content and rumen wall fractions were collected for ureC gene amplification and sequencing using Miseq. More than 55% of the ureC sequences did not affiliate with any known taxonomically assigned urease genes. The wall-adherent bacteria had a distinct ureolytic bacterial profile compared to the bacteria in the rumen content. The most abundant ureC genes were affiliated with Methylococcaceae, Clostridiaceae, Paenibacillaceae, Helicobacteraceae and Methylophilaceae families. Relative abundance of the operational taxonomic units (OTUs) affiliated with Methylophilus and Marinobacter genera were significantly higher in the bacteria on the rumen wall than that in the rumen content. Thirdly, based on the in vivo experiment, rumen fluid and blood samples were collected and analyzed using nuclear magnetic resonance spectroscopy and multivariate analysis of variance. Concentrations of valine, aspartate, glutamate, and uracil in the rumen, and urea and pyroglutamate in the plasma were increased after urea supplementation. Metabolic pathways include pantothenate and CoA biosynthesis, beta-alanine metabolism, valine, leucine, and isoleucine metabolism in the rumen, and urea and glutathione metabolism in the plasma were significantly increased by urea nitrogen. In conclusion, this study identified significant populations of ureolytic bacterial community that have not been recognized or studied previously in the rumen and provides a basis for obtaining regulatory targets to moderate urea hydrolysis in the rumen. The findings also provided novel information to aid understanding of the metabolic pathways affected by urea nitrogen in dairy cows, and could potentially help to guide efforts directed at improving the efficiency of urea utilization in the rumen. [less ▲]

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See detailHistoire évolutive du complexe Afzelia Smith (Leguminosae - Caesalpinioideae) dans les écosystèmes forestiers et savanicoles en Afrique tropicale
Donkpegan, Segbedji ULiege

Doctoral thesis (2017)

The genus Afzelia Smith (Fabaceae, Caesalpinioideae) is known to have seven African tree species two of which are found in the Zambezian region, one is distributed in the Sudanian region and the four ... [more ▼]

The genus Afzelia Smith (Fabaceae, Caesalpinioideae) is known to have seven African tree species two of which are found in the Zambezian region, one is distributed in the Sudanian region and the four other are endemic to the Guineo-Congolian region. These taxa, of high commercial value, are difficult to identify. They are therefore marketed under the same "doussié" name. These difficulties of distinction can prove detrimental to the sustainable management of populations. The aim of this doctoral thesis is to characterize the evolutionary history of the Afzelia genus. More specifically, this study aims to: (i) evaluate the level of morphological divergences within the Afzelia genus and describe the phylogenetic relationships in order to quantify the reproductive isolation between taxa by highlighting the role of past climate change and / or ecological gradients in the speciation of the genus; (ii) proceed to an analysis of the spatial genetic diversity and structure of Afzelia spp.; (iii) identify and describe ecological, biotic and abiotic factors that may influence population-level gene flows of an Afzelia species (A. bipindensis). A morpho-genetic analysis of Afzelia species was carried out and confirmed the strong botanical resemblance between the taxa. The savannah species are diploid and have half the size of the genome of forest species that are tetraploid. The phylogenies of genes (nuclear and chloroplastic) differ from one another and do not allow the separation of tetraploid taxa from one another. Such differences can be generated as a result of episodes of ancestral hybridization between species. These hybridizations would probably be old and would have occurred between lineages of the forest species and A quanzensis (a species of the Zambezian savannahs) lineages. Polyploidy would have occurred between 7 and 9.4 million years in the evolutionary history of the genus. In addition, Bayesian assignment and reproductive isolation analyzes suggested interspecific crosses, but only in forest species distributed sympatrically. At a more limited spatial scale, we observed two well differentiated genetic groups in sympatry in A. bipindensis. These show a morphological differentiation and a phenological shift of flowering which can contribute to their reproductive isolation. This study highlighted some important points: the discovery of a polyploid complex within the Afzelia genus, the confirmation of the delimitation of the diploid savannah species and the need to revise the delimitation of forest tetraploid species. [less ▲]

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See detailIon Mobility-Mass Spectrometry: Going beyond the numbers
Haler, Jean ULiege; Far, Johann ULiege; Béchet, Eric ULiege et al

Scientific conference (2017, July 03)

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See detailOn the Use of Principal Component Analysis for Parameter Identification and Damage Detection in Structures
Golinval, Jean-Claude ULiege

Conference (2017, July 03)

In this lecture, an approach based on principal component analysis (PCA) is considered for three purposes, namely damage detection, structural health monitoring and identification of nonlinear parameters ... [more ▼]

In this lecture, an approach based on principal component analysis (PCA) is considered for three purposes, namely damage detection, structural health monitoring and identification of nonlinear parameters in structural dynamics. The key idea of PCA is to reduce a large number of measured data to a much smaller number of uncorrelated variables while retaining as much as possible of the variation in the original data. The first problem to which PCA is applied here is the damage detection problem. When applied to vibration measurements, it can be shown that the basis of eigenvectors (called the proper orthogonal modes) span the same subspace as the mode-shape vectors of the monitored structure. Thus the damage detection problem may be solved using the concept of subspace angle between a reference subspace spanned by the eigenvectors of the initial (undamaged) structure and the subspace spanned by the eigenvectors of the current (possibly damaged) structure. The second problem concerns structural health monitoring of civil engineering structures when environmental effects (e.g. the influence of the variation of the ambient temperature) have to be removed from the structural changes. In this case, PCA may be applied on identified modal features (e.g. the natural frequencies) to separate the changes due to environmental variations from the changes due to damage sources. The third problem is related to the estimation of nonlinear parameters using model updating techniques. In this case, the most interesting property of PCA is that it minimizes the average squared distance between the original signal and its reduced linear representation. When applied to nonlinear problems, PCA gives the optimal approximating linear manifold in the configuration space represented by the data. The linear nature of the method is appealing because the theory of linear operators is still available. However, it should be borne in mind that it also exhibits its major limitation when the data lie on a nonlinear manifold. [less ▲]

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See detailEnhanced screening methods for pesticides in food based on travelling-wave ion-mobility-high-resolution mass spectrometry
Goscinny, Séverine ULiege

Doctoral thesis (2017)

The work presented in this thesis finds its origin in the need to develop ad hoc and novel analytical strategies to screen efficiently targeted pesticide residues in the sector of food control. Our work ... [more ▼]

The work presented in this thesis finds its origin in the need to develop ad hoc and novel analytical strategies to screen efficiently targeted pesticide residues in the sector of food control. Our work intended not only to monitor an increased number of pesticides but also to elaborate a new frame based on Ion Mobility-Mass Spectrometry (IMS-MS) for a confident and reliable use of screening pesticide data. The main part of this thesis was devoted to an investigation of using ion mobility, hyphenated to ultra-high performance liquid chromatography and Mass Spectrometry (UHPLC-IMS-MS), as a new dimension of separation for small polar organic molecules in complex biological samples without involving exhaustive sample preparation. The first objective of this study was dedicated to the development and optimization of UHPLC-IMS-MS using traveling wave ion mobility spectrometry (TWIMS). We have identified nitrogen as suitable gas for the mobility separation of multi-class pesticides and optimized the different T-wave parameters for a wide range of molecular weight pesticides. We observed for 100 pesticides tested that drift times gave a higher level of selectivity to the overall method as no interfering compound resulted at same retention time, drift time and measured mass from matrix blank samples. In addition, once the pesticide has been identified using its retention time, exact mass and drift time, the resulting cleaned mass spectrum facilitates the chemical structure elucidation. Key findings from this research show that drift times measurements are reproducible and independent from matrices tested and compound concentration leading to the proposition of using this parameter as a new identification point (IP). We have demonstrated that drift times can be used as an additional IP to increase confidence in the results without extending the analysis time or changing the sample preparation procedure. Based on reproducible data, we were the first group to report and recommend a 2% variation of drift times as quality criteria for identification purposes. In a few recent published papers, we noticed that research groups developing similar analytical strategies have extensively adopted the 2% proposed criterion. Obviously drift times are dependent of instrumental conditions. Hence, to apply the proposed approach with automated and wide scale screening methods further developments in processing software have been made which also allowed to convert drift times in calculated Collisional Cross Section (CCS) values by means of TWIMS calibration. The second aim of this thesis was dedicated to a comprehensive study of the reliability of CCS values derived from drift times for pesticides screening over a long period of time (3 years) with different ion mobility parameters. The results proved that CCS values are very consistent, as the measured values do not differ more than 1% from the in-house reference data library. Different calibration mixtures were also tested and results show that the type of the compound used for calibration does not influence CCS measurement. However, the results emphasized the importance of the first low m/z mobility calibration point (i.e. below 200 m/z) to guarantee full independence from instrument parameters and calibrant. The robustness of the CCS calibration was then tested by changing deliberately the IMS parameters and compare the measured CCSs with the reference CCSs. Three set of experiments were done by changing the IM velocity (static mode = fixed value and dynamic mode = velocity ramping) and also IM gas pressure. The first set of parameters gave CCS values within 2% error from the reference CCS throughout the pesticides mass range, while for the last 2 sets of parameters, deviations beyond 2% error away from the reference CCSs are clearly marked under the m/z 232 (first CCS calibration point). From these results, we clearly see that CCS values generated with the same calibration protocol are reproducible even for target masses under the first CCS calibration point, whereas robustness is guaranteed within the strict limits of the calibration range. To extend the calibration range to a larger window of molecular weights (in the lower and upper range) a combination of acetaminophene-polyalanine and a mixture of small molecules containing also polyalanine were tested. No significant deviations were observed between the two new calibration mixtures as all the pesticide results were within the 2% error. This observation demonstrates that the nature of the reference compounds used for calibration does not influence the outcome of the estimated CCS values for low molecular weight pesticides. Finally, an intercomparison study was designed to evaluate the relative capabilities of producing CCS values with a simple protocol for screening purposes. Four laboratories in three different countries (UK, USA and Belgium) were involved in the test. For this comparison, only monoisotopic ions were selected and 6 out of 40 pesticides selected had their masses under the first CCS calibration point (m/z 232). When comparing the percentage errors of each laboratory values to the calculated consensus value (mean of the CCS from the 4 instruments), two laboratories presented a few values outside the 2% error limits. Interestingly, when each laboratory used their in house reference CCS to calculate the percentage errors for a spiked mandarin extract, the results are well within the 2% CCS error window. These observations highlighted that the direct use of CCS values reported from the literature has to be treated with great care when applying the proposed approach. After this extensive study on CCS values, the third goal was to assess the possible added value of using CCS criterion when performing a UHPLC-IM-(HR)MS screening method of targeted pesticides. The approach has been tested in the framework of a proficiency test (EURL-PT-FV-16). The PT material was a sweet pepper homogenate containing 13 pesticides measured by LC in positive mode. Two additional pesticides can be added to this list, primicarb-desmethyl and tebuconazole, because they were in the sample but were not evaluated in the PT results by the organizers since their concentrations were below the minimum required reported limit of 0.01 mg kg-1. In total, we were expecting 15 detections by using our screening method. The approach proposed here is unconventional for screening and consists on one hand (scenario A), on large mass accuracy (20 ppm), large retention time window (0.5 min) and large CCS error (10%) in order to capture, in a first step, a maximum of detected compounds. 26 tentative candidates were then identified. In this scenario, when closing down first the mass accuracy window from 20 ppm to 5 ppm, 8 candidates were discarded. However, a wrong decision has been taken for two of them, (2 false negatives), requiring to trigger additional investigations. In the second step of scenario A, by selecting the 2% error for CCS, five additional residues did not meet the criterion and were ruling out, giving in total 13 detected compounds, actually present in the PT sample and 2 questionable data. In scenario B, when we directly apply a narrower CCS error percentage (from 10 to 2%) without filtering on mass accuracy we gain directly all the 15 compounds present in the PT sample without any false negatives and discard the 11 false positives in one step. These findings are indeed promising and require obviously confirmation at large scale within the pesticide laboratory end-users network equipped with IMS-MS and willing to apply the proposed screening strategy. Interlaboratory studies and PTs within the pesticide community are required to consolidate our findings during this thesis work. Regarding the treatment of data and software, considerable improvements have been made in terms of automatic extraction of mobility data and having a fully automated approach incorporating CCS values as a screening parameter has never been tested before this thesis. Nonetheless, there is room for improvements in terms of downsizing the acquisition file size which should enable faster processing and reporting time along with easier data storage. While the results from this thesis demonstrated that nitrogen was the most suited gas, Howdle et al. (1) have reported that the use of binary gas mixtures results in excellent selectivity enhancements over single gas composition for IMS separations and most importantly they demonstrated that this selectivity can be tuned by altering the binary gas composition. One can only barely imagine the impact of such results for IMS applications. Being able to choose the best gas mixture and/or develop gradient with variable gas composition during the mobility separation would most probably achieve better mobility resolution customized for specific applications or to create new opportunities for multi-class screening (e.g. pesticides, mycotoxins, food contact materials, food additives…). This new approach will trigger new research in the field of instrumental development to ensure control over the composition of gas delivered in the IMS cell and also how to adapt or create TWIMS calibration for these significant changes. The application space for ion mobility is vast, not only as a means of the specific pioneering application we developed here but in the richness of these measurements can provide in structural information of ions in many research fields including fundamental research. Conceptualization, design and construction of contemporary instruments were growing fast over the past few years. Emerging IM strategies developed by manufacturers based on proof-of-concept published papers encompass Overtone Mobility Spectrometry (OMS); confinement and mobility selective release like Trapped Ion Mobility Spectrometry (TIMS), or Cyclic Drift Tube Ion Mobility Spectrometry (Cyclic DTIMS) and more recently Cyclic Traveling Wave Ion Mobility Spectrometry (Cyclic TWIMS). For example, in Cyclic TWIMS, one remarkable feature is the use of one meter single path transit ring which was placed orthogonally to the primary beam travelling wave path of the instrument. This novel multi-pass cyclic device gives access to higher resolving power. As the Resolution (CCS/CCS) in T-wave increases in proportion to the square root of the device length, the one meter single pass in the ring being 4 times the length of a standard Synapt G2-S, the Resolution is doubled by cycle. Giles et al. reported up to 6 passes showing an acceptable ion transmission with a signal drop of only 15% (2). These emerging high-resolution IMS instruments clearly open new possibilities of separation of structural isomers low molecular weight compounds. Based on this research project, we are convinced that ion mobility used as an additional dimension of separation in hyphenated techniques can play a role in addressing the needs to provide reliable screening data and helping to reduce the rate of false negative and positive results prior to confirmation by quantitative methods. IMS-MS has become a key technology to answer chemical food safety issues as demonstrated by the rapidly expanding literature using IMS-MS over recent years. In a broader view, the concept of CCS data used as an additional identification tool and the development of new CCS databases will contribute to strengthen the needs in gathering reliable information to help the analyst in making right decision in the field of the very challenging qualitative screening analysis of trace chemical residues in food. [less ▲]

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See detailHow much should you jump? Reproducibility evaluation of a 3-dimensional fatigability countermovement jump test
Paulus, Julien ULiege; Schwartz, Cédric ULiege; Tubez, François ULiege et al

Conference (2017, July 02)

Introduction With the stop jump, the counter movement jump (CMJ) is probably the most used jump in sport. In the literature, a number of studies use the counter movement jump to explore (neuro-)muscular ... [more ▼]

Introduction With the stop jump, the counter movement jump (CMJ) is probably the most used jump in sport. In the literature, a number of studies use the counter movement jump to explore (neuro-)muscular fatigability [1-4]. However, due to the continuous [1-3] (or semi-continuous [4]) character of the test, the CMJ become drop jumps from the second one. Nevertheless, the drop jump isn't the most frequent jump type in sport. These evaluations, with (semi-)continuous jumps, don't reflect the sport reality and therefore a more effective (neuro-)muscular jumping fatigability evaluation must be validated. Methods Nineteen volleyball players (23,5 ± 3,3 years, 187,6 ± 6,6 cm, 77,5 ± 8,5 kg), with no history of (major) lower limb injury, submitted to two jumping fatigability tests, with seven days between each session, under the direction of a single researcher. The jumping fatigability tests consists of the repetition of 50 maximal CMJ at the rate of 33bpm. Between each CMJ, the subject were asked to make a full triple-extension and to wait the next auditory and visual signal of the metronome to start the hip-knee-ankle flexion. With these instructions, each jump remains a CMJ. Subjects were asked to leap as high as possible from the first to the last CMJ. The jumping height was recorder for each jump with three dimensional camera. The reproducibility was assessed by Standard Error of Measurement (SEM), Minimal Difference needed to be considered real (MD), Coefficient of Variation (CV), Pearson Correlation Coefficient (PCC) with 95% confidence interval, Effect Size Cohen (ES Cohen) with 90% confidence interval, paired Student's t-test, Intraclass Correlation Coefficient (ICC 2,1) with 95% confidence interval and Magnitude-Based Inferences (MBI). Results The results summary is available in the Table 1. In this table, only few parameters are presented and only for the partial sums of the first 10, 20, 25, 30, 40 and 50 jumps. Our analyses were based on the partial sums per interval of one jump and all statistical tests listed in "Methods" section have been considered. The partial sum with twenty-five CMJ have an excellent reproducibility (MBI with 0/99/1; ICC with 0.961 [0.902/0.985]; ES Cohen with -0.03 [-0.17/0.10]; PCC with 0.966 [0.911/0,987] and p-value < 0.0001). Moreover, it induce a great height decrease (-23%) and its duration (45.5 s) is similar to the recommendation for the knee fatigability isokinetic protocol [5]. MBI (+/trivial/-) Height decrease ICC (2,1) Test duration 10 0/100/0 -12,7% 0.967 18 s 20 0/99/1 -19,0% 0.964 36 s 25 0/99/1 -23,0% 0.961 46 s 30 0/98/1 -25,6% 0.955 55 s 40 0/98/1 -32,1% 0.950 73 s 50 0/98/2 -38,4% 0.943 91 s Table 1: reproducibility statistics results depending on the number of jumps considered (magnitude-based inferences (MBI) with percentage chances of better/trivial/worst retest vs test results; height jump decrease (last jump / better jump); ICC (2,1); test duration). Discussion Because of the (semi-)continuous character of a majority of fatigability jumping test [1-4], our test is the first, at our knowledge, to explore the reproducibility of a strict CMJ jumping fatigability task. Considering the statistical (relative and absolute) reproducibility results, twenty-five maximal CMJ seems to be the best compromise between reliability of the data and physiological interpretability of test's results. Indeed, its (relative and absolute) reproducibility is excellent and it induces a greater height decrease than shorter test while remaining similar in total duration than other fatigability tests which explore the anaerobic lactic system. References 1. Bosco et al, Eur J Appl Physiol Occup Physiol, 51(3):357-364, 1983. 2. Cormack et al., Int J Sports Physiol Perform, 3(2):131-44, 2008. 3. Dal Pupo et al., J Sci Med Sport, 17(6):650-5, 2014. 4. Meckel et al., J Strength Cond Res, 29(8):2122-7, 2015. 5. Bosquet et al., Int J Sports Med, 31(2):82-8, 2010. [less ▲]

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See detailSimultaneous Determination of Free Amino Acid Content in Different Teas using Supercritical Fluid Chromatography Coupled with Single Quadrupole Mass Spectrometry
Huang, Yang ULiege; Fillet, Marianne ULiege; Crommen, Jacques ULiege et al

Poster (2017, July 02)

Tea (Camellia sinensis L.) is a complex mixture containing a wide range of biological activities and has been used as widely consumed beverages and natural medicine for over thousand years [1-2]. In this ... [more ▼]

Tea (Camellia sinensis L.) is a complex mixture containing a wide range of biological activities and has been used as widely consumed beverages and natural medicine for over thousand years [1-2]. In this study, a novel method for high-performance liquid chromatography with mass spectrometry (SFC-MS) has been developed to simultaneously determine the contents of 11 free amino acids in different types of teas (pu-erh tea, green tea, black tea and oolong tea). The separation conditions for the selected amino acids were carefully optimized such as the column type, temperature and backpressure, the type of additive. The best compromise for tested analytes in terms of chromatographic performance was obtained when water (5%) and trifluoroacetate acid (0.4%) were added to the supercritical carbon dioxide/methanol mobile phase. Finally, the developed SFC-MS method was successfully applied to the analysis of the 11 amino acids present in the teas and fully validated as well. The results indicated a good linearity (r ≥0.995), precision (RSD≤ 2.99%), stability (RSD≤ 2.88%) and accuracy (91.95%~107.99%). The limits of detection ranged from 1.42 to 14.69 ng/mL, respectively, while the limits of quantification were between 4.53 and 47.0 ng/mL. The content of the amino acids in six different tea samples were also determined and presented some difference basing on the fermentation processes. The proposed SFC-MS method showed a great potential in further investigations to differentiate tea varieties [less ▲]

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See detailTesting the discrimination hypothesis for female self employment migrants in the UK
Constantinidis, Christina ULiege; Fletcher, Denise; Joxhe, Majlinda

in IAFFE (Ed.) Books of Abstracts (2017, July 01)

We propose a comparative analysis of migrants in both sectors (employment and self-employment) exploring the gender earning discrimination hypothesis. Using individual micro data from the British ... [more ▼]

We propose a comparative analysis of migrants in both sectors (employment and self-employment) exploring the gender earning discrimination hypothesis. Using individual micro data from the British Household Panel Survey (1991-2008), we estimate wage equations for employed and self-employed migrants and find that, contrary to our expectations, the average earnings gap in self-employment is almost double compared to the employment sector. This finding reveals that self-employment leads migrant women to an even more precarious and vulnerable position in terms of financial means and economic power. In addition, we explore the determinants of these gaps using the econometric procedure of the decomposition (the Blinder-Oaxaca) model. We find that the variables that explain the gender gap in the employment sector are mostly observable individual characteristics like education or migration duration, confirming the human capital theory, whereas in the self-employment sector, this gap is more due to unobservable individual characteristics. Through our work, we show that including the gender perspective into migration analysis has implications for policy makers enabling them to evaluate these processes from a more social (rather than individualistic) dimension. [less ▲]

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See detailMUSE-inspired view of the quasar Q2059-360, its Lyman α blob, and its neighborhood
North, P. L.; Marino, R. A.; Gorgoni, C. et al

in Astronomy and Astrophysics (2017), 604

The radio-quiet quasar Q2059-360 at redshift z = 3.08 is known to be close to a small Lyman α blob (LAB) and to be absorbed by a proximate damped Lyα (PDLA) system. Here, we present the Multi Unit ... [more ▼]

The radio-quiet quasar Q2059-360 at redshift z = 3.08 is known to be close to a small Lyman α blob (LAB) and to be absorbed by a proximate damped Lyα (PDLA) system. Here, we present the Multi Unit Spectroscopic Explorer (MUSE) integral field spectroscopy follow-up of this quasi-stellar object (QSO). Our primary goal is to characterize this LAB in detail by mapping it both spatially and spectrally using the Lyα line, and by looking for high-ionization lines to constrain the emission mechanism. Combining the high sensitivity of the MUSE integral field spectrograph mounted on the Yepun telescope at ESO-VLT with the natural coronagraph provided by the PDLA, we map the LAB down to the QSO position, after robust subtraction of QSO light in the spectral domain. In addition to confirming earlier results for the small bright component of the LAB, we unveil a faint filamentary emission protruding to the south over about 80 pkpc (physical kpc); this results in a total size of about 120 pkpc. We derive the velocity field of the LAB (assuming no transfer effects) and map the Lyα line width. Upper limits are set to the flux of the N v λ1238 - 1242, C iv λ1548 - 1551, He ii λ1640, and C iii] λ1548 - 1551 lines. We have discovered two probable Lyα emitters at the same redshift as the LAB and at projected distances of 265 kpc and 207 kpc from the QSO; their Lyα luminosities might well be enhanced by the QSO radiation. We also find an emission line galaxy at z = 0.33 near the line of sight to the QSO. This LAB shares the same general characteristics as the 17 others surrounding radio-quiet QSOs presented previously. However, there are indications that it may be centered on the PDLA galaxy rather than on the QSO. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programme 60.A-9331(A). [less ▲]

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See detailH0LiCOW - I. H0 Lenses in COSMOGRAIL's Wellspring: program overview
Suyu, S. H.; Bonvin, V.; Courbin, F. et al

in Monthly Notices of the Royal Astronomical Society (2017), 468

Strong gravitational lens systems with time delays between the multiple images allow measurements of time-delay distances, which are primarily sensitive to the Hubble constant that is key to probing dark ... [more ▼]

Strong gravitational lens systems with time delays between the multiple images allow measurements of time-delay distances, which are primarily sensitive to the Hubble constant that is key to probing dark energy, neutrino physics and the spatial curvature of the Universe, as well as discovering new physics. We present H0LiCOW (H[SUB]0[/SUB] Lenses in COSMOGRAIL's Wellspring), a program that aims to measure H[SUB]0[/SUB] with <3.5 per cent uncertainty from five lens systems (B1608+656, RXJ1131-1231, HE 0435-1223, WFI2033-4723 and HE 1104-1805). We have been acquiring (1) time delays through COSMOGRAIL and Very Large Array monitoring, (2) high-resolution Hubble Space Telescope imaging for the lens mass modelling, (3) wide-field imaging and spectroscopy to characterize the lens environment and (4) moderate-resolution spectroscopy to obtain the stellar velocity dispersion of the lenses for mass modelling. In cosmological models with one-parameter extension to flat Λ cold dark matter, we expect to measure H[SUB]0[/SUB] to <3.5 per cent in most models, spatial curvature Ω[SUB]k[/SUB] to 0.004, w to 0.14 and the effective number of neutrino species to 0.2 (1σ uncertainties) when combined with current cosmic microwave background (CMB) experiments. These are, respectively, a factor of ˜15, ˜2 and ˜1.5 tighter than CMB alone. Our data set will further enable us to study the stellar initial mass function of the lens galaxies, and the co-evolution of supermassive black holes and their host galaxies. This program will provide a foundation for extracting cosmological distances from the hundreds of time-delay lenses that are expected to be discovered in current and future surveys. [less ▲]

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See detailThe role of mucus in cell-based models used to screen mucosal drug delivery
Lechanteur, Anna ULiege; das Neves, José; Sarmento, Bruno

in Advanced Drug Delivery Reviews (2017)

The increasing interest in developing tools to predict drug absorption through mucosal surfaces is fostering the establishment of epithelial cell-based models. Cell-based in vitro techniques for drug ... [more ▼]

The increasing interest in developing tools to predict drug absorption through mucosal surfaces is fostering the establishment of epithelial cell-based models. Cell-based in vitro techniques for drug permeability assessment are less laborious, cheaper and address the concerns of using laboratory animals. Simultaneously, in vitro barrier models that thoroughly simulate human epithelia or mucosae may provide useful data to speed up the entrance of new drugs and new drug products into the clinics. Nevertheless, standard cell-based in vitro models that intend to reproduce epithelial surfaces often discard the role of mucus in influencing drug permeation/absorption. Biomimetic models of mucosae in which mucus production has been considered may not be able to fully reproduce the amount and architecture of mucus, resulting in biased characterization of permeability/absorption. In these cases, artificial mucus may be used to supplement cell-based models but still proper identification and quantification are required. In this review, considerations regarding the relevance of mucus in the development of cell-based epithelial and mucosal models mimicking the gastro-intestinal tract, the cervico-vaginal tract and the respiratory tract, and the impact of mucus on the permeability mechanisms are addressed. From simple epithelial monolayers to more complexes 3D structures, the impact of the presence of mucus for the extrapolation to the in vivo scenario is critically analyzed. Finally, an overview is provided on several techniques and methods to characterize the mucus layer over cell-based barriers, in order to intimately reproduce human mucosal layer and thereby, improve in vitro/in vivo correlation. [less ▲]

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See detailTrade unions and political culture(s) in the mining area of Kolwezi
Geenen, Kristien ULiege

Conference (2017, July 01)

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See detailModeling dermatophytosis in reconstructed human epidermis: A new tool to study infection mechanisms and to test antifungal agents
Faway, Emilie; Cambier, Ludivine; Mignon, Bernard ULiege et al

in Medical Mycology (2017), 55(5), 485-494

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See detailProbing the atmosphere of a sub-Jovian planet orbiting a cool dwarf
Sedaghati, Elyar; Boffin, Henri M. J.; Delrez, Laetitia et al

in Monthly Notices of the Royal Astronomical Society (2017), 468

We derive the 0.01 $\mu$m binned transmission spectrum, between 0.74 and 1.0 $\mu$m, of WASP-80b from low resolution spectra obtained with the FORS2 instrument attached to ESO's Very Large Telescope. The ... [more ▼]

We derive the 0.01 $\mu$m binned transmission spectrum, between 0.74 and 1.0 $\mu$m, of WASP-80b from low resolution spectra obtained with the FORS2 instrument attached to ESO's Very Large Telescope. The combination of the fact that WASP-80 is an active star, together with instrumental and telluric factors, introduces correlated noise in the observed transit light curves, which we treat quantitatively using Gaussian Processes. Comparison of our results together with those from previous studies, to theoretically calculated models reveals an equilibrium temperature in agreement with the previously measured value of 825K, and a sub-solar metallicity, as well as an atmosphere depleted of molecular species with absorption bands in the IR ($\gg 5\sigma$). Our transmission spectrum alone shows evidence for additional absorption from the potassium core and wing, whereby its presence is detected from analysis of narrow 0.003 $\mu$m bin light curves ($\gg 5\sigma$). Further observations with visible and near-UV filters will be required to expand this spectrum and provide more in-depth knowledge of the atmosphere. These detections are only made possible through an instrument-dependent baseline model and a careful analysis of systematics in the data. [less ▲]

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