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See detailMonte Carlo simulations of the dose from imaging with GE eXplore 120 micro-CT using gate.
Bretin, Florian; Bahri, Mohamed Ali ULg; Luxen, André ULg et al

in Medical Physics (2015), 42(10), 5711-5719

Purpose: Small animals are increasingly used as translational models in preclinical imaging studies, during which the subjects can be exposed to large amounts of radiation. While the radiation levels are ... [more ▼]

Purpose: Small animals are increasingly used as translational models in preclinical imaging studies, during which the subjects can be exposed to large amounts of radiation. While the radiation levels are generally sublethal, studies have shown that low-level radiation can change physiological parameters in mice. In order to rule out any influence of radiation on the outcome of such experiments, or resulting deterministic effects in the subjects, the levels of radiation involved need to be addressed. The aim of this study was to investigate the radiation dose delivered by the GE eXplore 120 microCT non-invasively using Monte Carlo simulations in GATE and to compare results to previously obtained experimental values. Methods: Tungsten X-ray spectra were simulated at 70, 80, and 97 kVp using an analytical tool and their half-value layers were simulated for spectra validation against experimentally measured values of the physical X-ray tube. A Monte Carlo model of the microCT system was set up and four protocols that are regularly applied to live animal scanning were implemented. The computed tomography dose index (CTDI) inside a PMMA phantom was derived and multiple field of view acquisitions were simulated using the PMMA phantom, a representative mouse and rat. Results: Simulated half-value layers agreed with experimentally obtained results within a 7% error window. The CTDI ranged from 20 to 56 mGy and closely matched experimental values. Derived organ doses in mice reached 459 mGy in bones and up to 200 mGy in soft tissue organs using the highest energy protocol. Dose levels in rats were lower due to the increased mass of the animal compared to mice. The uncertainty of all dose simulations was below 14%. Conclusions: Monte Carlo simulations proved a valuable tool to investigate the 3D dose distribution in animals from microCT. Small animals, especially mice (due to their small volume), receive large amounts of radiation from the GE eXplore 120 microCT, which might alter physiological parameters in a longitudinal study setup. [less ▲]

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See detailCharacterization of the magnetic properties of a continuously coated YBCO coated conductor cylinder in persistent current mode
Wera, Laurent ULg; Fagnard, Jean-François ULg; Hogan, Kevin ULg et al

Poster (2015, September 09)

YBCO coated conductors are good candidates for magnetic shielding applications because of (i) their high current density and (ii) their lower weight compared to magnetic shields made of bulk HTS materials ... [more ▼]

YBCO coated conductors are good candidates for magnetic shielding applications because of (i) their high current density and (ii) their lower weight compared to magnetic shields made of bulk HTS materials. In particular, an efficient superconducting magnetic shield can be built as an assembly of milled YBCO 2G coated conductor tape sections, or, as in this case, a continuously coated cylinder. The purpose of the present work is to characterize experimentally the DC magnetic properties of a continuous band of YBCO film (about 1 cm width) deposited around a hastelloy cylinder of 6.4 cm in diameter. In particular, we characterize the distribution and the time dependence of the trapped field inside the cylinder due to persistent current loops. We also investigate the magnetic shielding properties at several sweep rates when the applied magnetic field is parallel to the main axis of the cylinder. All measurements are carried out at 77 K. The measurement of the trapped field of the cylinder gives evidence that a persistent current of about 80 A can be induced in the YBCO band. Magnetic shielding measurements show that, thanks to the persistent current flowing in the band, the cylinder is able to attenuate by a factor of 2 the applied magnetic field. These results open interesting perspectives for a further development of magnetic shields made of coated conductor cylinders. We investigate how the shielding performances could be further improved by increasing the number of layers and by increasing the height of the cylinder. The results are compared to a multilayer coated conductor cylinder with joints and to persistent current loops obtained with milled coated conductor tape sections. [less ▲]

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See detailMagnetic shielding properties of a bulk Bi-2223 superconducting hollow cylinder subjected to the magnetic stray field of a nearby magnetic source
Hogan, Kevin ULg; Wera, Laurent ULg; Fagnard, Jean-François ULg et al

Poster (2015, September 09)

Superconducting materials act as efficient magnetic shields thanks to their intrinsic magnetic properties. At low frequencies, their efficiency even surpasses that of conventional ferromagnetic materials ... [more ▼]

Superconducting materials act as efficient magnetic shields thanks to their intrinsic magnetic properties. At low frequencies, their efficiency even surpasses that of conventional ferromagnetic materials. Therefore, they can be very useful for many applications which require low or very low magnetic field in intense quasi-static magnetic environments. The vast majority of studies on superconducting screens has been conducted in homogeneous magnetic field configurations. Few works have been done concerning inhomogeneous magnetic field configurations while those are representative of practical situations. Moreover, those configurations are non-trivial given the magnetic hysteretic behaviour of type-II superconductors. In the present work, we aim at investigating and understanding the shielding properties of a superconducting hollow cylinder made of Bi-2223 subjected to the magnetic stray field of a coil placed in the vicinity. All experiments are carried out at 77K. [less ▲]

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See detailStraw-bale walls for sustainable architecture: Improving and promoting straw-bale use in European Buildings
Evrard, Arnaud; Biot, Benjamin; Keutgen, Gauthier et al

in Cucinella; Giulia (Eds.) Architecture in (R)Evolution (2015, September 09)

Straw-bale use in buildings may be an interesting way to decrease our energy needs and our impact on the environment. Moreover, it fosters a local economy and the creation of new jobs in the building ... [more ▼]

Straw-bale use in buildings may be an interesting way to decrease our energy needs and our impact on the environment. Moreover, it fosters a local economy and the creation of new jobs in the building industry. Combined with earth materials and other well-selected materials and systems, it allows creative designers to integrate highly efficient, low-tech and reusable envelopes in comfortable and healthy places. The present paper summarizes the results of a four year R&D program aiming to improve and promote the use of straw bale in buildings and also to remove uncertainties concerning this use. Three main aspects are pinpointed and discussed: hygrothermal transfer and storage in straw-bale walls, regulation of indoor conditions and environmental impact in the long term. These three topics were submitted to European experts (France, England and Germany) in order to discuss a cross-comparison of results obtained on a larger scale. The paper shows that straw-bale use in buildings is a relevant and innovative solution in facing one of the major challenges of today and tomorrow: "How to build/transform comfortable and affordable buildings with local resources and with a positive impact on the environment?". [less ▲]

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See detailWhat do they mean? Listening to babies communicating in the daily setting in ECEC service
Pirard, Florence ULg; Legrand, Anne; Michel, Aurore ULg

Conference (2015, September 09)

The main aim of the study was to gain understanding of how babies communicate in ECEC services. Previous literature indicates that babies can interact and communicate precociously, not only with adults ... [more ▼]

The main aim of the study was to gain understanding of how babies communicate in ECEC services. Previous literature indicates that babies can interact and communicate precociously, not only with adults (Stern, 2005; Threvarten, 2011), but also with other children (Tomasello et al., 2005). The ECEC service can be considered as a setting where interaction and communication between peers can be sustained by practitioners who observe them, document what happens, analyse together the educational condition to guarantee and regulate their action (Stambak et al., 1983). The study involved qualitative and action research initiated by Cresas and IEDPE (self-regulating participatory assessment, Ballion et al., 1988), combined with an analysis of activity approach focused on contextualised process. An action researcher has gathered practitioners, trainers and researchers from France, Spain, Croatia, Italy and Belgium to analyse educational daily practice in ECEC services and their effect on communication between peers. Videos have been used to document and analyse the practice (EADAP, 2011). The ethical considerations taken in this study involved collaborative perspectives that give an active place to all participants (researchers, trainers, practitioners? parents and children). Informed consent and authorization for using video in the research are guaranteed. Participants identify and document communication processes between very young children observed in natural setting (ECEC services). These processes are characterised by several aspects: duration, emotional expression and meaningful linking of observed behaviours between babies. A shared meaning from the video documentation can be co-constructed like some narrative stories. Participants consider the activity of babies as meaningful stories that they should understand and sustain with interest. We discuss implications for professionalisation of the workforce (initial training and professional development). [less ▲]

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See detailComposite dark matter and direct-search experiments
Wallemacq, Quentin ULg

Doctoral thesis (2015)

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See detailRisk Factors and Control Measures for Bacterial Contamination in the Bovine Meat Chain: A Review on Salmonella and Pathogenic E.coli.
Niyonzima, Eugene ULg; Ongol, Martin Patrick; Kimonyo, Anastase et al

in Journal of Food Research (2015), 4(5), 98-121

Salmonella and pathogenic Escherichia coli are known to be the major bacterial agents responsible for human foodborne infections attributable to meat. A review of the specialized literature was carried ... [more ▼]

Salmonella and pathogenic Escherichia coli are known to be the major bacterial agents responsible for human foodborne infections attributable to meat. A review of the specialized literature was carried out to identify the risk factors for bovine meat contamination by these pathogens from the cattle farm to meat consumption. Animal stress during transport to the slaughterhouse and the duration of the lairage period were identified as the key factors influencing the faecal excretion of Salmonella and pathogenic E. coli as well as cattle contamination prior to slaughter. At the abattoir level, hides and visceral contents appear to be the main sources of pathogenic bacteria that contaminate carcasses along the meat production chain. Finally, temperature abuses during distribution and meat contamination by infected handlers were found to be important contributors to the post-slaughter contamination of bovine meat. The findings of this study indicate that efficient management of human food borne infections attributable to bovine meat requires an integrated application of control measures involving all actors along the meat chain, namely slaughterhouses, meat processing plants, distributors and consumers. [less ▲]

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See detailHigh dendritic expression of Ih in the proximity of the axon origin controls the integrative properties of nigral dopamine neurons.
Engel, Dominique ULg; Seutin, Vincent ULg

in Journal of Physiology (2015), 593(22), 4905-4922

Dendrites of most neurons express voltage-gated ion channels in their membrane. In combination with passive properties, active currents confer to dendrites a high computational potential. The ... [more ▼]

Dendrites of most neurons express voltage-gated ion channels in their membrane. In combination with passive properties, active currents confer to dendrites a high computational potential. The hyperpolarization-activated cation current Ih present in the dendrites of some pyramidal neurons affects their membrane and integration properties, synaptic plasticity and higher functions such as memory. A gradient of increasing h-channel density towards distal dendrites has been found to be responsible for the location independence of excitatory postsynaptic potential (EPSP) waveform and temporal summation in cortical and hippocampal pyramidal cells. However, reports on other cell types revealed that smoother gradients or even linear distributions of Ih can achieve homogeneous temporal summation. Although the existence of a robust, slowly activating Ih current has been repeatedly demonstrated in nigral dopamine neurons, its subcellular distribution and precise role in synaptic integration are unknown. Using cell-attached patch-clamp recordings, we find a higher Ih current density in the axon-bearing dendrite than in the soma or in dendrites without axon in nigral dopamine neurons. Ih is mainly concentrated in the dendritic membrane area surrounding the axon origin and decreases with increasing distances from this site. Single EPSPs and temporal summation are similarly affected by blockade of Ih in axon- and non-axon-bearing dendrites. The presence of Ih close to the axon is pivotal to control the integrative functions and the output signal of dopamine neurons and may consequently influence the downstream coding of movement. [less ▲]

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See detailReevaluating IUCN Red List assesment on European amphibians
Crnobrnja-Isailović, Jelka; Cogalniceanu, Dan; Denoël, Mathieu ULg et al

Conference (2015, September 09)

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See detailPractical training session on virus discovery from High Throughput Sequencing data
Massart, Sébastien ULg

Conference (2015, September 09)

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See detailAls Staat stabilisiert, als Nation gescheitert? Belgien in der Nachkriegszeit (1945-ca. 1950)
Brüll, Christoph ULg

Scientific conference (2015, September 09)

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See detailIconic virtues of diagrams. Peirce and ampliative reasoning
Leclercq, Bruno ULg

Conference (2015, September 08)

In his Critic of pure reason, Immanuel Kant notoriously claimed that, being grounded on the forms of sense intuition, arithmetical and geometrical propositions are both synthetic (i.e. informative) and a ... [more ▼]

In his Critic of pure reason, Immanuel Kant notoriously claimed that, being grounded on the forms of sense intuition, arithmetical and geometrical propositions are both synthetic (i.e. informative) and a priori. Bernard Bolzano, followed in this by the logicist movement (from Gottlob Frege to Rudolf Carnap), answered that the generality and necessity of mathematical propositions and proofs can only be grounded on conceptual analysis. Even though, just like Frege, he is one of the fathers of formal logic, Charles Sanders Peirce provides some semiotic reasons to think that Kant was right: diagrams do convey general meanings and provide some knowledge which is necessary yet non-trivial. Unlike logical analysis, visual presentation of concepts in schemas or diagrams helps to explore concepts by stressing some of their “side” features in such a way that new knowledge is gained: « diagrams evolve what was involved » (CP4/86). This is why, according to Kant’s notion of intuitive construction, mathematical inferences are not merely deductive but are inventive and ampliative. My talk aims at identifying some iconic virtues of diagrams which, according to Peirce, explain their epistemic productivity. A first one lies in the “formal” nature of icons, which allows them to express syntactic relations between descriptive (symbols) and demonstrative (indices) components of structured information. On this respect, even algebraic and ideographic expressions are icons exhibiting a general form – a “rheme” – in which places for indices are filled with variables “x” and “y” meaning “any individual”. For this reason, even though they are singular, diagrams are “abstractions” in the sense that they represent relations rather than their terms. Only with this in prospect can a second, and more studied, feature of diagrams matter, namely their two-dimensionality, which helps to exhibit complex relations that cannot be seen on linear linguistic expressions. Finally, a third feature of diagrams lies in their imaginary rather than referential character. Icons connote without denoting, and therefore they can be informational without this information being limited to singular individuals. Furthermore, this non referential character of icons is what makes them open to virtual exploratory manipulations that allow to consider and investigate possibilities which in turn inform us on not obvious properties of the presently visible configuration. [less ▲]

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See detailThe leaders profile method: detection of distinct processes in a signal
Kleyntssens, Thomas ULg; Nicolay, Samuel ULg

Poster (2015, September 08)

The leaders profile method is a multifractal formalism that allows to compute non-concave and non-increasing spectra. Our implementation can detect the presence of distinct processes in a signal. We ... [more ▼]

The leaders profile method is a multifractal formalism that allows to compute non-concave and non-increasing spectra. Our implementation can detect the presence of distinct processes in a signal. We present here the first results obtained. [less ▲]

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See detailA wavelet-based mode decomposition compared to the EMD
Deliège, Adrien ULg; Nicolay, Samuel ULg

Poster (2015, September 08)

We introduce a new method based on wavelets for decomposing a signal into quasi-periodic oscillating components with smooth time-varying amplitudes. This method is inspired by both the "classic" wavelet ... [more ▼]

We introduce a new method based on wavelets for decomposing a signal into quasi-periodic oscillating components with smooth time-varying amplitudes. This method is inspired by both the "classic" wavelet-based decomposition and the empirical mode decomposition (EMD). We compare the efficiency of the method with the well-established EMD on toys examples and the ENSO climate index. [less ▲]

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See detailYear Round Survey of Ocean-Sea Ice-Air Exchanges – the YROSIAE survey
Delille, Bruno ULg; Van Der Linden, Fanny ULg; Fripiat, François et al

Poster (2015, September 08)

YROSIAE survey aimed to carry out a year-round integrated survey of land-fast sea ice focusing on the study of sea ice physics and biogeochemistry in order to a) better understand and budget exchanges of ... [more ▼]

YROSIAE survey aimed to carry out a year-round integrated survey of land-fast sea ice focusing on the study of sea ice physics and biogeochemistry in order to a) better understand and budget exchanges of energy and matter across the ocean-sea ice-atmosphere interfaces during sea ice growth and decay and b) quantify their potential impact on fluxes of climate gases (CO2, DMS, CH4, N2O) to the atmosphere and on carbon and macro- nutrients and micro-nutrients export to the ocean. We will present the aims, overall approach and integrated sampling strategy of the YROSIAE survey. We will also discuss CO2 and N2O dynamics within sea ice. It appears that sea ice acts as a source of CO2 for the atmosphere in winter, counterbalancing spring sink. In addition, mineralization in spring appears to alleviate spring CO2 uptake. Intense nitrification in sea ice in spring fosters emission of N2O at the air-ice interface. [less ▲]

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See detailEthylene polymerization mediated by nickel(II) covalently anchored to silica xerogels
Lambert, Stéphanie ULg; Sacco, Luigi

Conference (2015, September 08)

Heterogeneous catalysis is generally widely preferred for industrial applications thanks to the well-known advantages of easier product-catalyst separation and recovery of the catalyst process and, often ... [more ▼]

Heterogeneous catalysis is generally widely preferred for industrial applications thanks to the well-known advantages of easier product-catalyst separation and recovery of the catalyst process and, often, to the enhanced stability of the catalyst. But in terms of selectivity, homogeneous catalysis usually provides better results. From this point of view, the grafting of homogeneous catalysts onto a solid support seems the ideal combination in order to achieve the advantages of both heterogeneous and homogeneous catalysis, allowing the developing of more environmentally friendly and economical processes with potential application in the industry. Further, to covalently link a homogeneous onto silica (a support which is thermally, chemically and mechanically resistant, with a well defined structure) is the best way to limit metal leaching and sintering. Nitrogen-based ligands containing one of several Schiff bases have been reported to form active catalysts with “late-metal” (such as Fe, Pd, Ni,…) for the ethylene polymerization [1]. Moreover, substituted pyrazole-based organometallic complexes gave also promising results in this field. These facts let us suggest that the pyrazolylpyridine derivatives bearing a tethered trimethoxysilylated group synthesized in a previous work [2] are potentially good candidate to prepare hybrid catalyst (i.e. soluble organometallic complexes covalently bonded onto an insoluble support, in this case silica) with Ni-II, Fe-II or Pd-II for ethylene polymerization. [less ▲]

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See detailPremières notes pour l'ethnographie d'un projet européen en situation embarquée
Thoreau, François ULg

Conference (2015, September 08)

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See detailDe la maladie chronique à la multimorbidité : quel impact sur l’organisation des soins de santé ?
Belche, Jean-Luc ULg; Berrewaerts, Marie-Astrid ULg; Ketterer, Frédéric ULg et al

in Presse Médicale (2015)

Healthcare systems are concerned with the growing prevalence of chronic diseases. Single disease approach, based on the Chronic Care Model, is known to improve specific indicators for the targeted disease ... [more ▼]

Healthcare systems are concerned with the growing prevalence of chronic diseases. Single disease approach, based on the Chronic Care Model, is known to improve specific indicators for the targeted disease. However, the co-existence of several chronic disease, or multimorbidity, within a same patient is the most frequent situation. The fragmentation of care, as consequence of the single disease approach, has negative impact on the patient and healthcare professionals. A person centred approach is a method addressing the combination of health issues of each patient. The coordination and synthesis role is key to ensure continuity of care for the patient within a network of healthcare professionals from several settings of care. This function is the main characteristic of an organized first level of care. [less ▲]

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