Les forêts anciennes en Wallonie. 2ème partie : Cartographie

Un premier article a démontré que l’identification des forêts anciennes est une étape préalable pour pouvoir leur appliquer un mode de gestion spécifique et protéger le patrimoine qu’elles représentent. Cette deuxième partie énumère les sources historiques disponibles en Wallonie, donne un aperçu de l’état d’avancement du travail de numérisation de ces documents mené par le Service Public de Wallonie et en tire quelques informations très surprenantes sur l’évolution spatiale et temporelle des massifs forestiers de Wallonie depuis deux siècles et demi

Use of the 3D radon transform to examine the properties of oceanic Rossby waves

One of the most successful applications of satellite-borne radar altimeter data over the oceans in recent years has been the extraction of information about long-wavelength baroclinic Rossby (or planetary) waves, which play a significant role in ocean circulation and climate dynamics. These waves cross ocean basins from east to west at speeds of few centimetres per second at mid-latitudes. The cross-basin propagation time may therefore be several months or even years and an accurate estimation of the speed of the waves is important. We review the methods for obtaining information on Rossby wave velocity from altimetry data, particularly the two-dimensional Radon transform. Unfortunately the use of longitude-time plots, although it allows the estimation of the zonal phase speeds, does not give any information on the speed vector when the propagation of the waves is not purely zonal (east-west). We show how the two-dimensional Radon Transform can be generalised to three dimensions, enabling not only the true propagation velocity component to be determined, but also the direction of the waves and thus any deviation from the pure-westward case. As examples of the application of this extended technique, we show maps of direction, speed and energy of Rossby waves in the North Atlantic Ocean

Improvement of CO2 hydrate formation and flow using chemical additives in a slurry loop and a stirred reactor: applications to refrigeration and CO2 capture

Secondary refrigeration and thermal energy storage techniques could be interesting solutions to improve refrigerating system performances and to reduce power consumption and propagation of refrigerants in the atmosphere. In order to combine a more efficient secondary loop and fluids with higher energy storage capacity, a phase change material (PCM) slurry, also called phase change slurry (PCS), could be used as secondary refrigerant. In addition, hydrate-based processes could be an interesting option to separate the CO2 from various gas mixtures. In these two applications, the flow properties of the CO2 hydrate slurry are of paramount importance. In the present study, small amounts of Sodium Dodecyl Sulfate (SDS) were added to the aqueous phase, and this system was tested under CO2 pressure both in a dynamic flow loop and in a stirred reactor. The results obtained with the flow loop demonstrate that SDS has anti-agglomerant properties for the CO2 hydrate: SDS significantly decreases agglomeration and thus improves flowing capacities of the slurry. The results obtained in the reactor shows that the presence of SDS increases the kinetics of the hydrate growth rate both in agitated and in quiescent hydrate forming conditions. Consequently, the addition of SDS could be very promising in industrial applications, such as secondary refrigeration or gas separation, where hydrate slurries must be easily handled and where the hydrate formation rate is of great importance

Loss-of-function alleles of P2RX7 and TLR4 fail to affect the response to chemotherapy in non-small cell lung cancer

The success of anticancer chemotherapy relies at least in part on the induction of an immune response against tumor cells. Thus, tumors growing on mice that lack the pattern recognition receptor TLR4 or the purinergic receptor P2RX7 fail to respond to chemotherapy with anthracyclins or oxaliplatin in conditions in which the same neoplasms growing on immunocompetent mice would do so. Similarly, the therapeutic efficacy (measured as progression-free survival) of adjuvant chemotherapy with anthracyclins is reduced in breast cancer patients bearing loss-of-function alleles of TLR4 or P2RX7. TLR4 loss-of-function alleles also have a negative impact on the therapeutic outcome of oxaliplatin in colorectal cancer patients. Here, we report that loss-of-function TLR4 and P2RX7 alleles do not affect overall survival in non-small cell lung cancer (NSCLC) patients, irrespective of the administration and type of chemotherapy. The intrinsic characteristics of NSCLC (which near-to-always is chemoresistant and associated with poor prognosis) and/or the type of therapy that is employed to treat this malignancy (which near-to-always is based on cisplatin) may explain why two genes that affect the immune response to dying cells fail to influence the clinical progression of NSCLC patients

Complex nature of apparently balanced chromosomal rearrangements in patients with autism spectrum disorder

Background: Apparently balanced chromosomal rearrangements can be associated with an abnormal phenotype, including intellectual disability and autism spectrum disorder (ASD). Genome-wide microarrays reveal cryptic genomic imbalances, related or not to the breakpoints, in 25% to 50% of patients with an abnormal phenotype carrying a microscopically balanced chromosomal rearrangement. Here we performed microarray analysis of 18 patients with ASD carrying balanced chromosomal abnormalities to identify submicroscopic imbalances implicated in abnormal neurodevelopment. Methods: Eighteen patients with ASD carrying apparently balanced chromosomal abnormalities were screened using single nucleotide polymorphism (SNP) arrays. Nine rearrangements were de novo, seven inherited, and two of unknown inheritance. Genomic imbalances were confirmed by fluorescence in situ hybridization and quantitative PCR. Results: We detected clinically significant de novo copy number variants in four patients (22%), including three with de novo rearrangements and one with an inherited abnormality. The sizes ranged from 3.3 to 4.9 Mb; three were related to the breakpoint regions and one occurred elsewhere. We report a patient with a duplication of the Wolf-Hirschhorn syndrome critical region, contributing to the delineation of this rare genomic disorder. The patient has a chromosome 4p inverted duplication deletion, with a 0.5 Mb deletion of terminal 4p and a 4.2 Mb duplication of 4p16.2p16.3. The other cases included an apparently balanced de novo translocation t(5;18)(q12;p11.2) with a 4.2 Mb deletion at the 18p breakpoint, a subject with de novo pericentric inversion inv(11)(p14q23.2) in whom the array revealed a de novo 4.9 Mb deletion in 7q21.3q22.1, and a patient with a maternal inv(2)(q14.2q37.3) with a de novo 3.3 Mb terminal 2q deletion and a 4.2 Mb duplication at the proximal breakpoint. In addition, we identified a rare de novo deletion of unknown significance on a chromosome unrelated to the initial rearrangement, disrupting a single gene, RFX3. Conclusions: These findings underscore the utility of SNP arrays for investigating apparently balanced chromosomal abnormalities in subjects with ASD or related neurodevelopmental disorders in both clinical and research settings

Platelets Alter Gene Expression Profile in Human Brain Endothelial Cells in an In Vitro Model of Cerebral Malaria

Platelet adhesion to the brain microvasculature has been associated with cerebral malaria (CM) in humans, suggesting that platelets play a role in the pathogenesis of this syndrome. In vitro co-cultures have shown that platelets can act as a bridge between Plasmodium falciparum-infected red blood cells (pRBC) and human brain microvascular endothelial cells (HBEC) and potentiate HBEC apoptosis. Using cDNA microarray technology, we analyzed transcriptional changes of HBEC in response to platelets in the presence or the absence of tumor necrosis factor (TNF) and pRBC, which have been reported to alter gene expression in endothelial cells. Using a rigorous statistical approach with multiple test corrections, we showed a significant effect of platelets on gene expression in HBEC. We also detected a strong effect of TNF, whereas there was no transcriptional change induced specifically by pRBC. Nevertheless, a global ANOVA and a two-way ANOVA suggested that pRBC acted in interaction with platelets and TNF to alter gene expression in HBEC. The expression of selected genes was validated by RT-qPCR. The analysis of gene functional annotation indicated that platelets induce the expression of genes involved in inflammation and apoptosis, such as genes involved in chemokine-, TREM1-, cytokine-, IL10-, TGFβ-, death-receptor-, and apoptosis-signaling. Overall, our results support the hypothesis that platelets play a pathogenic role in CM

Habitat selection in forest birds and predictive models of species' potential distributions in Ardenne's oak and beech forests : effects of tree composition and forest stand structure

Les exigences en terme d'habitat de l'avifaune forestière ne sont pas suffisamment connues pour pouvoir proposer des mesures de gestion qui permettent de maintenir les populations des espèces aviaires dans le temps et dans l'espace. De même, la modification des communautés d'oiseaux en fonction de la composition et de la structure des peuplements feuillus est peu ou pas connue. Les objectifs de la thèse sont donc l'identification, à l'échelle intra-peuplement, des facteurs clés de l'habitat d'oiseaux des chênaies et hêtraies ardennaises et la modélisation des exigences de ces espèces en vue d'établir les bases nécessaires pour la construction de cartes d'habitats potentiels. L'identification des facteurs clés de l'habitat permet de déterminer des indicateurs de gestion afin de pouvoir évaluer l'impact d'interventions sylvicoles. La méthodologie développée s'appuie sur l'étude de la sélection des habitats par différentes espèces et la construction de modèles autécologiques et synécologiques. L'étude de la sélection et de la modélisation de l'habitat d'espèces cibles et de communautés d'oiseaux à une échelle locale s'appuie sur un inventaire précis de la végétation de quatre massifs forestiers ardennais (sud de la Belgique) couvrant 1975 ha. L'étude des communautés d'oiseaux a permis de déterminer les espèces indicatrices de la qualité des chênaies et hêtraies ardennaises et de voir comment évoluent la richesse et la composition des communautés d'oiseaux en fonction de la structure du peuplement et de la composition forestière. La sélection et la modélisation des habitats ont été étudiées pour trois espèces cibles : le pic mar (Dendrocopos medius), le pic épeichette (Dendrocopos minor) et le pouillot siffleur (Phylloscopus sibilatrix). Notre étude a permis de définir des seuils pour les facteurs essentiels de l'habitat de ces espèces comme par exemple, le nombre de gros bois, la proportion d'essences héliophiles telles que le chêne et le bouleau, le volume de bois morts sur pied, les strates de végétation et le taillis. La modélisation des habitats pour les trois espèces cibles a tenu compte de l'autocorrélation spatiale des données. Cette étude met en évidence la présence de cohésion sociale entre individus de pouillot siffleur.Too little is known about the forest avifauna in terms of habitat to be able to put forward management measures allowing for the preservation of the population of avian species in time and space. Likewise, very little, if anything, is known about the evolution of bird communities in relation with the composition and the structure of deciduous forest stands. Therefor the aim of the thesis is the identification on a stand scale of key parameters of bird habitats in the oak and beech forests of the Ardenne and the modelisation of the requirements of these species with a view to set up the foundations necessary for the drawing of potential habitat maps. The identification of the key parameters of the habitat gives the means to determine management indicators for the evaluation of the impact of sylvicultural treatments. The developed methodology is based on the study of the habitat selection by various species and on the construction of autecological and synecological models. The study of the selection and modelisation of the habitat for target species and bird communities on a local scale is based on an accurate inventory of vegetation in four forest massifs of the Ardenne. The study of the bird communities led to specify which species were indicators of the quality of oak and beech forests in the Ardenne, and also to understand how the diversity and the composition of the bird communities were affected by the stand structure and the tree composition. The selection and the modelisation of the habitats were studied for three target species : the middle spotted woodpecker (Dendrocopos medius), the lesser spotted woodpecker (Dendrocopos minor) and the wood warbler (Philloscopus sibilatrix). The study resulted in the establishment of thresholds for the key parameters of the habitat of these species such as the number of large trees, the proportions of heliophile species like oaks and birch, the volume of standing dead wood, the vegetation layers and the coppice. The modelisation of the habitats for the three target species takes into account the spatial autocorrelation of the data. This study also brings to the fore the existence of a social cohesion pattern among wood warblers

Les forêts anciennes en Wallonie. 1ère partie : Concepts généraux

Au cours des siècles, la forêt wallonne a subi de profondes mutations qui marquent encore la structure et le fonctionnement des écosystèmes forestiers actuels. Néanmoins, certaines forêts ont été relativement épargnées. Ces forêts, qualifiées de « forêts anciennes » en raison de la continuité temporelle de leur état forestier, s’avèrent d’un grand intérêt en matière de biodiversité, de naturalité de fonctionnement et de capacité d’adaptation aux changements globaux. Leur reconnaissance et leur identification sont utiles pour assurer une gestion responsable des territoires

Etudes expérimentales de la densité énergétique des coulis de paraffines et hydrates de gaz

International audienceDue to the high increase of energy consumption and after Montreal and Kyoto protocols, it has been necessary to reduce power consumption and the propagation of the refrigerants in the atmosphere by improving the performances of the refrigerating machines. In this context, the use of Thermal Energy Storage (TES) techniques could be an interesting solution. Classical secondary refrigerants, such as water and glycol aqueous solutions, are single phase fluids limited by their small cold carrying capacity. Moreover, secondary refrigerants need the use of additional pumps leading to high thermodynamic irreversibilities. In order to combine a more efficient secondary loop and fluids with higher energy storage capacity, a phase change material (PCM) slurry could be used as secondary refrigerant. In such systems, energy is stored mainly during a phase change process of the storage material and a carrier fluid should be used as a continuous phase. The obtained system is called Phase Change Slurry (PCS). PCS has a higher energy density than single-phase secondary refrigerants due to both sensible and latent heat capacities of the materials. In the present work, three types of PCS systems were investigated: CO2 hydrate slurry, paraffin dispersion and hydrate-paraffin slurry. CO2 hydrate slurry was already studied at Irstea (France) and it was found that its dissociation enthalpy (500 kJ.kg-1water) was higher than that of ice (333 kJ/kg). Studies on paraffins latent heat enthalpy were already accomplished only under atmospheric pressure at the Fraunhofer institute (Germany) and the total emulsion enthalpy was largely higher than then sensible heat of pure water. It was also shown that paraffin dispersions have good flowing capacities. The purpose of this work is to combine CO2 hydrate and paraffin dispersion systems in order to reach a PCS system that combines the advantages in terms of melting enthalpy and flowing capacities. Therefore, a DTA device was used in which the phase change temperatures and the corresponding enthalpies for many PCS systems were measured. The best system must verify some requirements: stability over a large period of time, high storage density (higher than ice), good flowing capacities and phase transformation between 0 and 20 °C under moderate pressure