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See detailIncorporation of iron and organic matter into young Antarctic sea ice during its initial growth stages
Janssens, Julie; Meiners, Klaus M.; Tison, Jean-Louis et al

in Elementa: Science of the Anthropocene (2016), 4(1), 000123

This study reports concentrations of iron (Fe) and organic matter in young Antarctic pack ice and during its initial growth stages in situ. Although the importance of sea ice as an Fe reservoir for ... [more ▼]

This study reports concentrations of iron (Fe) and organic matter in young Antarctic pack ice and during its initial growth stages in situ. Although the importance of sea ice as an Fe reservoir for oceanic waters of the Southern Ocean has been clearly established, the processes leading to the enrichment of Fe in sea ice have yet to be investigated and quantified. We conducted two in situ sea-ice growth experiments during a winter cruise in the Weddell Sea. Our aim was to improve the understanding of the processes responsible for the accumulation of dissolved Fe (DFe) and particulate Fe (PFe) in sea ice, and of particulate organic carbon and nitrogen, dissolved organic carbon, extracellular polymeric substances, inorganic macro-nutrients (silicic acid, nitrate and nitrite, phosphate and ammonium), chlorophyll a and bacteria. Enrichment indices, calculated for natural young ice and ice newly formed in situ, indicate that during Antarctic winter all of the measured forms of particulate matter were enriched in sea ice compared to underlying seawater, and that enrichment started from the initial stages of sea-ice formation. Some dissolved material (DFe and ammonium) was also enriched in the ice but at lower enrichment indices than the particulate phase, suggesting that size is a key factor for the incorporation of impurities in sea ice. Low chlorophyll a concentrations and the fit of the macro-nutrients (with the exception of ammonium) with their theoretical dilution lines indicated low biological activity in the ice. From these and additional results we conclude that physical processes are the dominant mechanisms leading to the enrichment of DFe, PFe, organic matter and bacteria in young sea ice, and that PFe and DFe are decoupled during sea-ice formation. Our study thus provides unique quantitative insight into the initial incorporation of impurities, in particular DFe and PFe, into Antarctic sea ice. [less ▲]

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See detailModel Sensitivity Studies of the Decrease in Atmospheric Carbon Tetrachloride
Chipperfield, M. P.; Liang, Q.; Rigby, M. et al

in Atmospheric Chemistry & Physics Discussions (2016), 2016

Carbon tetrachloride is an ozone-depleting substance, which is controlled by the Montreal Protocol and for which the atmospheric abundance is decreasing. However, the current observed rate of this ... [more ▼]

Carbon tetrachloride is an ozone-depleting substance, which is controlled by the Montreal Protocol and for which the atmospheric abundance is decreasing. However, the current observed rate of this decrease is known to be slower than expected based on reported CCl4 emissions and its estimated overall atmospheric lifetime. Here we use a three-dimensional (3-D) chemical transport model to investigate the impact on its predicted decay of uncertainties in the rates at which CCl4 is removed from the atmosphere by photolysis, by ocean uptake and by degradation in soils. The largest sink is atmospheric photolysis (76% of total) but a reported 10% uncertainty in its combined photolysis cross-section and quantum yield has only a modest impact on the modelled rate of CCl4 decay. This is partly due to the limiting effect of the rate of transport of CCl4 from the main tropospheric reservoir to the stratosphere where photolytic loss occurs. The model suggests large interannual variability in the magnitude of this stratospheric photolysis sink caused by variations in transport. The impact of uncertainty in the minor soil sink (9% of total) is also relatively small. In contrast, the model shows that uncertainty in ocean loss (15% of total) has the largest impact on modelled CCl4 decay due to its sizeable contribution to CCl4 loss and large uncertainty range (157 to 313 years). With an assumed CCl4 emission rate of 39 Gg/yr, the reference simulation with best estimate of loss processes still underestimates the observed CCl4 (overestimates the decay) over the past two decades but to a smaller extent than previous studies. Changes to the rate of CCl4 loss processes, in line with known uncertainties, could bring the model into agreement with in situ surface and remote-sensing measurements, as could an increase in emissions to around 45 Gg/yr. Further progress in constraining the CCl4 budget is partly limited by systematic biases between observational datasets. For example, surface observations from the NOAA network are larger than from the AGAGE network but have shown a steeper decreasing trend over the past two decades. These differences imply a difference in emissions which is significant relative to uncertainties in the magnitudes of the CCl4 sinks. [less ▲]

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See detailCanine idiopathic pulmonary fibrosis : improvement of the phenotype characterization and search for biomarkers and for etiologic agents
Roels, Elodie ULg

Doctoral thesis (2016)

Canine idiopathic pulmonary fibrosis (CIPF) is a progressive parenchymal lung disease of unknown origin, mainly described in old-aged West Highland white terriers (WHWTs). It is characterized by exercise ... [more ▼]

Canine idiopathic pulmonary fibrosis (CIPF) is a progressive parenchymal lung disease of unknown origin, mainly described in old-aged West Highland white terriers (WHWTs). It is characterized by exercise intolerance, cough and dyspnoea/tachypnea with a progressive deterioration until death from respiratory insufficiency. CIPF shares clinical features with human idiopathic pulmonary fibrosis (IPF), while tomodensitometric and histopathological findings do not appear to be exactly the same. Over the past 10 years, several studies have been performed to improve our knowledge about CIPF. However, this disease is still misunderstood and clinicians are dealing with several challenges including the absence of clinical or biological markers for estimating the presence, severity or progression of the disease and related comorbidities such as pulmonary hypertension, the absence of etiologic agent, and the absence of targeted therapy. Consequently, the aims of the present project were (1) to investigate whether high-resolution computed tomography (HRCT) of the lungs obtained under sedation can be used for the diagnosis and for the follow-up of the disease, (2) to study a new echocardiographic parameter for the diagnosis of precapillary pulmonary hypertension induced by CIPF, (3) to study the potential roles of 2 chemokines of interest, CCL2 and CXCL8, as biomarkers of fibrosis and as actors in the pathogenesis of the disease, (4) to determine breed variation of basal blood concentrations of the same chemokines, vascular endothelial growth factor (VEGF), and serotonin, and (5) to search for the presence of herpesvirus as a possible etiologic agent. [less ▲]

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See detailA Comparison between four Techniques to Measure Cardiac Output
Pironet, Antoine ULg; Dauby, Pierre ULg; Chase, J. Geoffrey et al

Poster (2016, August 17)

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See detailA Comparison between four Techniques to Measure Cardiac Output
Pironet, Antoine ULg; Dauby, Pierre ULg; Chase, J. Geoffrey et al

in Proceedings of the 38th International Conference of the IEEE Engineering in Medicine and Biology Society (2016, August 17)

Cardiac output is an important variable when monitoring hemodynamic status. In particular, changes in cardiac output represent the goal of several circulatory management therapies. Unfortunately, cardiac ... [more ▼]

Cardiac output is an important variable when monitoring hemodynamic status. In particular, changes in cardiac output represent the goal of several circulatory management therapies. Unfortunately, cardiac output is very difficult to estimate, either in experimental or clinical settings. The goal of this work is to compare four techniques to measure cardiac output: pressure-volume catheter, aortic flow probe, thermodilution, and the PiCCO monitor. These four techniques were simultaneously used during experiments of fluid and endotoxin administration on 7 pigs. Findings show that, first, each individual technique is precise, with a relative coefficient of repeatability lower than 7 %. Second, 1 cardiac output estimate provided by any technique relates poorly to the estimates from the other 3, even if there is only small bias between the techniques. Third, changes in cardiac output detected by one technique are only detected by the others in 62 to 100 % of cases. This study confirms the difficulty of obtaining a reliable clinical cardiac output measurement. Therefore, several measurements using different techniques should be performed, if possible, and all such should be treated with caution. [less ▲]

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See detailÉmotion, ipséité, liberté. Réflexions à propos des fondements de la théorie sartrienne des émotions
Recchia, Fabio ULg

in Bulletin d'Analyse Phénoménologique (2016), 12(5), 1-23

Entretenue durant la drôle de guerre, la correspondance épistolaire entre De Beauvoir et Sartre révèle une insatisfaction de ce dernier à l'égard de sa théorie des émotions. Celle-ci manquerait en effet ... [more ▼]

Entretenue durant la drôle de guerre, la correspondance épistolaire entre De Beauvoir et Sartre révèle une insatisfaction de ce dernier à l'égard de sa théorie des émotions. Celle-ci manquerait en effet de fondements solides. Répondant à ce constat, nous tenterons de dégager les fondations de cette théorie de manière à expliciter ses enjeux. Nous replacerons, pour ce faire, l'Esquisse d'une théorie des émotions dans la perspective plus générale de la théorie de l'intentionnalité du premier Sartre. De la sorte nous montrerons, d'une part, comment ce texte renouvelle significativement la catégorie de l'action en concevant l'émotion comme une activité ; et nous examinerons, d'autre part, l'interaction existant entre l¿émotion et l'ipséité de la conscience. Cette discussion dévoilera ainsi l'intentionnalité émotive comme une passion active reconduisant au fondement de la conscience qui est sa liberté personnelle. [less ▲]

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See detailReformulations of nonlinear binary optimization problems
Crama, Yves ULg

Scientific conference (2016, August 17)

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See detailThe Chemistry of New Garlic-Derived Organosulfur Compounds and the Molecular Basis of Olfaction »
Dethier, Bérénice ULg

Doctoral thesis (2016)

Garlic is a very popular condiment that has been used around the world for centuries. It is also a source of a remarkably extensive range of organosulfur compounds, whose chemistry is the focus of this ... [more ▼]

Garlic is a very popular condiment that has been used around the world for centuries. It is also a source of a remarkably extensive range of organosulfur compounds, whose chemistry is the focus of this thesis. The central reaction in formation of these compounds is the enzymatic cleavage of alk(en)yl cysteine sulfoxides by alliinases, which leads to sulfenic acids. The latter can then undergo condensation and rearrangement into various organosulfur compounds. Three aspects of the chemistry of garlic have been investigated in this thesis. First, little studied, minor organosulfur compounds in extracts of freshly chopped garlic were studied. These higher molecular weight compounds (MW 150–550) can be conveniently studied using state-of-the-art Liquid Chromatography-Mass Spectrometry (LC-MS) and Direct Analysis in Real Time-Mass Spectrometry (DART-MS) techniques. Novel garlic-derived compounds were studied and the structure of one representative compound containing a five-membered thiolane ring, ajothiolane, was determined by spectroscopic methods, using synthetic analogues as spectroscopic standards. The fate of compounds in a garlic extract over time was also studied, since the new, higher mass sulfur compounds are slowly formed by rearrangement of smaller metabolites a few days after maceration of the garlic. A second part of this thesis provides hands-on methods for the analysis and preparation of key garlic metabolites. The isolation and/or synthesis of alliin, alliinase and vinyldithiins have been optimized, and are proposed as turnkey procedures for future work. Finally, in an effort to explain the unique odor of garlic-related thiols and sulfides (in garlic breath, sweat, etc.), the interactions between odorants and olfactory receptors have been studied. Work described in this thesis contributed to this larger project by designing and synthesizing model macrocyclic odorants to resolve the mechanism of olfaction at the receptor level. The conclusions, arguing against the plausibility of the so-called “vibration theory of olfaction”, have been published as a foundation for future work on olfactory detection of thiols and other sulfur-containing compounds. [less ▲]

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See detailUse of slow-release plant infochemicals to control aphids: a first investigation in a Belgian wheat field
Zhou, Haibo; Chen, Longsheng; Liu, Yong et al

in Scientific Reports (2016)

Using infochemicals to develop a push–pull strategy in pest control is a potential way to promote sustainable crop production. Infochemicals from plant essential oils were mixed with paraffin oil for slow ... [more ▼]

Using infochemicals to develop a push–pull strategy in pest control is a potential way to promote sustainable crop production. Infochemicals from plant essential oils were mixed with paraffin oil for slow release in field experiments on wheat to control the population density of cereal aphids and to enhance their natural enemies. (Z)-3-Hexenol (Z3H) attracted Metopolophum dirhodum and Sitobion avenae, the predominant species on wheat in Belgium, and may be a useful infochemical for aphid control by attracting aphids away from field plots. Release of (E)-β-farnesene (EBF) or a garlic extract (GE) led to a significant decrease in the abundance of wheat aphids. The main natural enemies of cereal aphids found were lacewings (47.8%), hoverflies (39.4%), and ladybirds (12.8%). Ladybird abundance varied little before the end of the wheat-growing season. Our results suggest that these chemicals can form the basis of a “push–pull” strategy for aphid biological control, with GE and EBF acting as a pestand beneficial-pulling stimulus and Z3H for aphid pulling. [less ▲]

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See detailCASTLE4D : The castle of Franchimont
Luczfalvy Jancsó, Andrea ULg; Hoffsummer, Patrick ULg; Billen, Roland ULg et al

Poster (2016, August 16)

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See detailHuman herpesvirus 8-encoded chemokine vCCL2/vMIP-II is an agonist of the atypical chemokine receptor ACKR3/CXCR7
Szpakowska, Martyna; Dupuis, Nadine ULg; Baragli, Alessandra et al

in Biochemical Pharmacology (2016), 114

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See detailA new global interior ocean mapped climatology: the 1° × 1° GLODAP version 2
Lauvset, Siv K.; Key, Robert M.; Olsen, Are et al

in Earth System Science Data (2016)

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See detailBackground subtraction and background generation
Van Droogenbroeck, Marc ULg

Conference (2016, August 15)

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See detailUlcerative pododermatitis and disseminated erosive lesions associated with cowpox virus infection in a domestic cat
Ludwig, Louisa ULg; Bohn, Jéromine ULg; Remy, Isabelle ULg et al

in Veterinary Record Case Reports (2016)

The authors report on a case of feline cowpox virus infection associated with severe ulcerative dermatitis of a paw and disseminated erosive lesions. While the anamnesis of the cat being a known rodent ... [more ▼]

The authors report on a case of feline cowpox virus infection associated with severe ulcerative dermatitis of a paw and disseminated erosive lesions. While the anamnesis of the cat being a known rodent-hunter, a typical seasonality of infection and the progression of clinical signs from a primary anterior lesion (forelimb) indicated a possible cowpox virus infection, the differential diagnosis was complicated by the resemblance of clinical signs to those induced by feline herpesvirus-dermatitis or feline calicivirus infection. These differential diagnoses were excluded by means of immunostaining and PCR, respectively. Detection of eosinophilic intracytoplasmic inclusion bodies in cells from biopsy material and positive PCR and sequencing results confirmed the diagnosis of cowpox virus infection. Genetic characterisation of the isolate, based on the highly diverse haemagglutinin gene, showed that the strain (Liege 2015; GenBank accession number: KU726584) clustered with other European isolates, mostly from exotic zoo animals. [less ▲]

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See detailCharacterization of stony soils' hydraulic conductivity using laboratory and numerical experiments
Beckers, Eléonore ULg; Pichault, Mathieu; Pansak, Wanwisa et al

in SOIL (2016), 2

Determining soil hydraulic properties is of major concern in various fields of study. Although stony soils are widespread across the globe, most studies deal with gravel-free soils, so that the literature ... [more ▼]

Determining soil hydraulic properties is of major concern in various fields of study. Although stony soils are widespread across the globe, most studies deal with gravel-free soils, so that the literature describing the impact of stones on the hydraulic conductivity of a soil is still rather scarce. Most frequently, models characterizing the saturated hydraulic conductivity of stony soils assume that the only effect of rock fragments is to reduce the volume available for water flow, and therefore they predict a decrease in hydraulic conductivity with an increasing stoniness. The objective of this study is to assess the effect of rock fragments on the saturated and unsaturated hydraulic conductivity. This was done by means of laboratory experiments and numerical simulations involving different amounts and types of coarse fragments. We compared our results with values predicted by the aforementioned predictive models. Our study suggests that it might be ill-founded to consider that stones only reduce the volume available for water flow. We pointed out several factors of the saturated hydraulic conductivity of stony soils that are not considered by these models. On the one hand, the shape and the size of inclusions may substantially affect the hydraulic conductivity. On the other hand, laboratory experiments show that an increasing stone content can counteract and even overcome the effect of a reduced volume in some cases: we observed an increase in saturated hydraulic conductivity with volume of inclusions. These differences are mainly important near to saturation. However, comparison of results from predictive models and our experiments in unsaturated conditions shows that models and data agree on a decrease in hydraulic conductivity with stone content, even though the experimental conditions did not allow testing for stone contents higher than 20 %. [less ▲]

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See detailFunctional analysis of protein tyrosine phosphatases in thrombosis and haemostasis
Rahmouni, Souad ULg; Hego, Alexandre ULg; Delierneux, Céline ULg et al

in Protein Tyrosine Phosphatases: Methods and Protocols (2016)

Platelets are small blood cells derived from cytoplasmic fragments of megakaryocytes and play an essential role in thrombosis and haemostasis. Platelet activation depends on the rapid phosphorylation and ... [more ▼]

Platelets are small blood cells derived from cytoplasmic fragments of megakaryocytes and play an essential role in thrombosis and haemostasis. Platelet activation depends on the rapid phosphorylation and dephosphorylation of key signaling molecules, and a number of kinases and phosphatases have been identified as major regulators of platelet function. However, the investigation of novel signaling proteins has suffered from technical limitations due to the anucleate nature of platelets and their very limited levels of mRNA and de novo protein synthesis. In the past, experimental methods were restricted to the generation of genetically modified mice and the development of specific antibodies. More recently, novel (phospho)proteomic technologies and pharmacological approaches using specific small-molecule inhibitors have added additional capabilities to investigate specific platelet proteins. In this chapter, we report methods for using genetic and pharmacological approaches to investigate the function of platelet signaling proteins. While the described experiments focus on the role of the dual-specificity phosphatase 3 (DUSP3) in platelet signaling, the presented methods are applicable to any signaling enzyme. Specifically, we describe a testing strategy that includes 1) aggregation and secretion experiments with mouse and human platelets, 2) immunoprecipitation and immunoblot assays to study platelet signaling events, 3) detailed protocols to use selected animal models in order to investigate thrombosis and haemostasis in vivo, and 4) strategies for utilizing pharmacological inhibitors on human platelets. [less ▲]

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See detailFunctional analysis of dual-specificity protein phosphatases in angiogenesis
Amand, Mathieu; ERPICUM, Charlotte ULg; Gilles, Christine ULg et al

in Pulido, Rafael (Ed.) Protein Tyrosine Phosphatases: Methods and Protocols (2016)

Therapeutic perspectives targeting angiogenesis in cancer stimulated an intense investigation of the mechanisms triggering and governing angiogenic processes. Several publications have highlighted the ... [more ▼]

Therapeutic perspectives targeting angiogenesis in cancer stimulated an intense investigation of the mechanisms triggering and governing angiogenic processes. Several publications have highlighted the importance of typical dual-specificity phosphatases (DSPs) or MKPs in endothelial cells and their role in controlling different biological functions implicated in angiogenesis such as migration, proliferation, apoptosis, tubulogenesis and cell adhesion. However, among atypical DSPs, the only one investigated in angiogenesis was DUSP3. We recently identified this DSP as new key player in endothelial cells and angiogenesis. In this chapter we provide with detailed protocols and models used to investigate the role of DUSP3 in endothelial cells and angiogenesis. We start the chapter with an overview of the role of several DSPs in angiogenesis. We continue with providing a full description of a highly efficient transfection protocol to deplete DUSP3 using small interfering RNA (siRNA) in the primary Human Umbilical Vein Endothelial Cells (HUVEC). We next describe the major assays used to investigate different processes involved in angiogenesis such as tube formation assay, proliferation assay and spheroids sprouting assay. We finish the chapter by validating our results in DUSP3-knockout mice using in vivo angiogenesis assays such as Matrigel plug and Lewis lung carcinoma cell subcutaneous xenograft model followed by anti-CD31 immunofluorescence and ex vivo aortic ring assay. All methods described can be adapted to other phosphatases and signaling molecules. [less ▲]

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See detailAnnual Greenland accumulation rates (2009–2012) from airborne snow radar
Koenig, L.; Ivanoff, A.; Alexander, P. et al

in Cryosphere (The) (2016), 10

Contemporary climate warming over the Arctic is accelerating mass loss from the Greenland Ice Sheet through increasing surface melt, emphasizing the need to closely monitor its surface mass balance in ... [more ▼]

Contemporary climate warming over the Arctic is accelerating mass loss from the Greenland Ice Sheet through increasing surface melt, emphasizing the need to closely monitor its surface mass balance in order to improve sea-level rise predictions. Snow accumulation is the largest component of the ice sheet's surface mass balance, but in situ observations thereof are inherently sparse and models are difficult to evaluate at large scales. Here, we quantify recent Greenland accumulation rates using ultra-wideband (2–6.5 GHz) airborne snow radar data collected as part of NASA's Operation IceBridge between 2009 and 2012. We use a semiautomated method to trace the observed radiostratigraphy and then derive annual net accumulation rates for 2009–2012. The uncertainty in these radar-derived accumulation rates is on average 14 %. A comparison of the radar-derived accumulation rates and contemporaneous ice cores shows that snow radar captures both the annual and long-term mean accumulation rate accurately. A comparison with outputs from a regional climate model (MAR) shows that this model matches radar-derived accumulation rates in the ice sheet interior but produces higher values over southeastern Greenland. Our results demonstrate that snow radar can efficiently and accurately map patterns of snow accumulation across an ice sheet and that it is valuable for evaluating the accuracy of surface mass balance models. [less ▲]

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