Does time since fire drive live aboveground biomass and stand structure in low fire activity boreal forests? Impacts on their management

Boreal forests subject to low fire activity are complex ecosystems in terms of structure and dynamics. They have a high ecological value as they contain important proportions of old forests that play a crucial role in preserving biodiversity and ecological functions. They also sequester important amounts of carbon at the landscape level. However, the role of time since fire in controlling the different processes and attributes of those forests is still poorly understood. The Romaine River area experiences a fire regime characterized by very rare but large fires and has recently been opened to economic development for energy and timber production. In this study, we aimed to characterize this region in terms of live aboveground biomass, merchantable volume, stand structure and composition, and to establish relations between these attributes and the time since the last fire. Mean live aboveground biomass and merchantable volume showed values similar to those of commercial boreal coniferous forests. They were both found to increase up to around 150 years after a fire before declining. However, no significant relation was found between time since fire and stand structure and composition. Instead, they seemed to mostly depend on stand productivity and non-fire disturbances. At the landscape level, this region contains large amounts of biomass and carbon stored resulting from the long fire cycles it experiences. Although in terms of merchantable volume these forests seemed profitable for the forest industry, a large proportion were old forests or presented structures of old forests. Therefore, if forest management was to be undertaken in this region, particular attention should be given to these old forests in order to protect biodiversity and ecological functions. Partial cutting with variable levels of retention would be an appropriate management strategy as it reproduces the structural complexity of old forests

Resistive switching and charge transport mechanisms in ITO/ZnO/p-Si devices

[EN] The resistive switching properties of ITO/ZnO/p-Si devices have been studied, which present well-defined resistance states with more than five orders of magnitude difference in current. Both the high resistance state (HRS) and the low resistance state (LRS) were induced by either sweeping or pulsing the voltage, observing some differences in the HRS. Finally, the charge transport mechanisms dominating the pristine, HRS, and LRS states have been analyzed in depth, and the obtained structural parameters suggest a partial re-oxidation of the conductive nanofilaments and a reduction of the effective conductive area.This work was financially supported by the Spanish Ministry of Economy and Competitiveness (Project Nos. TEC2012-38540-C02-01 and TEC2016-76849-C2-1-R). O.B. also acknowledges the subprogram "Ayudas para Contratos Predoctorales para la Formacion de Doctores" of the Spanish Ministry of Economy and Competitiveness for economical support. 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Dose to organ at risk and dose prescription in liver SBRT

Stereotactic body radiation therapy (SBRT) is delivered in a curative intent to many primary and secondary tumors.Concerning liver metastasis, SBRT can be safely delivered using one to five fractions. An excellent local control is obtained with doses from 20 to 60[[ce:hsp sp="0.25"/]]Gy. For primary hepatic tumors, results are also good, but the risk of hepatic toxicity related to liver pre-existent pathology must be taken into account. Radiation induced liver disease (RILD) is not frequent in its classical presentation, but modifications of liver enzymes are often observed. Other toxicities of SBRT on the duodenum, small bowel and biliary tract are also described. With respect to contraindications and dose limitations on surrounding structures, SBRT is well tolerated and takes place among curative treatment of liver tumors, as surgery, radiofrequency and embolization

Light-activated electroforming in ITO/ZnO/p-Si resistive switching devices

We report on light-activated electroforming of ZnO/p-Si heterojunction memristors with transparent indium tin oxide as the top electrode. Light-generated electron-hole pairs in the p-type substrate are separated by the external electric field and electrons are injected into the active ZnO layer. The additional application of voltage pulses allows achieving different resistance states that end up in the realization of the low resistance state (LRS). This process requires much less voltage compared to dark conditions, thus avoiding undesired current overshoots and achieving a self-compliant device. The transport mechanisms governing each resistance state are studied and discussed. An evolution from an electrode-limited to a space charge-limited transport is observed along the electroforming process before reaching the LRS, which is ascribed to the progressive formation of conductive paths that consequently induce the growth of conductive nanofilaments through the ZnO layer. This work was financially supported by the Spanish Ministry of Economy and Competitiveness (Project Nos. TEC2012-38540-C02-01 and TEC2016-76849-C2-1-R). O.B. also acknowledges the subprogram "Ayudas para Contratos Predoctorales para la Formación de-Doctores" from the Spanish Ministry of Economy and Competitiveness for economical support. J.L.F. acknowledges the subprogram "Ayudas para la Formación de Profesorado Universitario" (No. FPU16/06257) from the Spanish Ministry of Education, Culture and Sports for economical support. X.P., C.L., and C.G. are grateful to C. Frilay for his expertise in the maintenance of the sputtering setup used for the growth of the ZnO films

Physiological parameters and evaluation of the upper and lower respiratory airways in french standardbred trotters during a standardised exercise on a treadmill

Cette étude a été réalisée chez 115 chevaux âgés de deux à neuf ans, prêts à courir ou participant à des courses. Les animaux étaient divisés en deux groupes : 23 chevaux obtenant de bons résultats en course et constituant le groupe témoin, et 92 chevaux n'obtenant pas de bons résultats. L'exercice standardisé comprenait dix minutes d'échauffement au petit trot, puis trois paliers d'exercice de trois minutes chacun. Après les trois paliers, le cheval était arrêté une minute, l'endoscope était mis en place, et un quatrième palier était effectué à vitesse maximale. La fréquence cardiaque (FC) était mesurée en continu pendant le test et un échantillon de sang était prélevé par un cathéter placé dans l'artère faciale transverse pendant les dix dernières secondes de chaque palier. Une heure après l'exercice, un lavage broncho-alvéolaire (LBA) était effectué. Les résultats concernant la FC, la lactatémie et la PaO2 suggèrent qu'il existe une différence significative dans la réponse métabolique à l'exercice entre les chevaux contre-performants et les chevaux du groupe témoin. L'endoscopie à l'exercice et le LBA ont permis de répartir les chevaux contre-performants en quatre groupes selon la localisation des affections: affections des voies respiratoires supérieures (VRS), affections des voies respiratoires profondes (VRP), affections des VRS et des VRP, et autres affections. Ces examens ont aussi permis d'évaluer la réponse métabolique à l'exercice dans les différentes situations. La réalisation d'un LBA après exercice peut fournir des informations importantes et ce, même chez des chevaux présentant une affection évidente des voies respiratoires supérieures.This study was carried out in 115 horses between 2 and 9 years old, ready to race or actively racing. The animals were divided into two groups: 23 horses with good racing results representing the control group, and 92 horses with poor racing results. The standardised exercise test started with a 10 min warm-up at a slow trot, followed by 3 periods of exercise of 3 min each. After the three periods, the horse was stopped on the treadmill for 1 min, the endoscope was inserted, and the horse performed a fourth period at maximal speed. The heart rate (HR) was measured throughout the test and blood was collected via a catheter inserted in the transverse facial artery during the last 10 seconds of each period. One hour after the exercise, a broncho-alveolar lavage (BAL) was performed. The results of this study (HR, blood lactate, PaO2) suggest that there is a significant difference in the metabolic response to exercise between poor performers and good performers. The results of the endoscopy during exercise and post-exercise BAL were used to divide poor performers into 4 groups, based on the localisation of the problem : upper respiratory airway (URA) disease, lower respiratory airway (LRA) disease, URA and LRA disease, and other diseases. These tests were also used to evaluate the metabolic response to exercise in the different situations. Post-exercise BAL may provide important information, even in horses with evidence of upper respiratory disease

Toward RGB LEDs based on rare earth-doped ZnO

By using ZnO thin films doped with Ce, Tb or Eu, deposited via radiofrequency magnetron sputtering, we have developed monochromatic (blue, green and red, respectively) light emitting devices (LEDs). The rare earth ions introduced with doping rates lower than 2% exhibit narrow and intense emission peaks due to electronic transitions in relaxation processes induced after electrical excitation. This study proves zinc oxide to be a good host for these elements, its high conductivity and optical transparency in the visible range being as well exploited as top transparent electrode. After structural characterization of the different doped layers, a device structure with intense electroluminescence is presented, modeled, and electrically and optically characterized. The different emission spectra obtained are compared in a chromatic diagram, providing a reference for future works with similar devices. The results hereby presented demonstrate three operating monochromatic LEDs, as well as a combination of the three species into another one, with a simply-designed structure compatible with current Si technology and demonstrating an integrated red-green-blue emission

Thrombin modifies growth, proliferation and apoptosis of human colon organoids: a protease-activated receptor 1- and protease-activated receptor 4-dependent mechanism

International audienceExperimental Approach: Crypts were isolated from human colonic resections and cultured for 6 days, forming human colon organoids. Cultured organoids were exposed to 10 and 50 mU·mL−1 of thrombin, in the presence or not of protease‐activated receptor (PAR) antagonists. Organoid morphology, metabolism, proliferation and apoptosis were followed.Key Results: Thrombin favoured organoid maturation leading to a decreased number of immature cystic structures and a concomitant increased number of larger structures releasing cell debris and apoptotic cells. The size of budding structures, metabolic activity and proliferation were significantly reduced in organoid cultures exposed to thrombin, while apoptosis was dramatically increased. Both PAR1 and PAR4 antagonists inhibited apoptosis regardless of thrombin doses. Thrombin‐induced inhibition of proliferation and metabolic activity were reversed by PAR4 antagonist for thrombin's lowest dose and by PAR1 antagonist for thrombin's highest dose.Conclusions and Implications: Overall, our data suggest that the presence of thrombin in the vicinity of human colon epithelial cells favours their maturation at the expense of their regenerative capacities. Our data point to thrombin and its two receptors PAR1 and PAR4 as potential molecular targets for epithelial repair therapies

Optimization and design of an aircraft's morphing wing-tip demonstrator for drag reduction at low speeds, Part II - Experimental validation using Infra-Red transition measurement from Wind Tunnel tests

In the present paper, an ‘in-house’ genetic algorithm was numerically and experimentally validated. The genetic algorithm was applied to an optimization problem for improving the aerodynamic performances of an aircraft wing tip through upper surface morphing. The optimization was performed for 16 flight cases expressed in terms of various combinations of speeds, angles of attack and aileron deflections. The displacements resulted from the optimization were used during the wind tunnel tests of the wing tip demonstrator for the actuators control to change the upper surface shape of the wing. The results of the optimization of the flow behavior for the airfoil morphing upper-surface problem were validated with wind tunnel experimental transition results obtained with infra-red Thermography on the wing-tip demonstrator. The validation proved that the 2D numerical optimization using the ‘in-house’ genetic algorithm was an appropriate tool in improving various aspects of a wing’s aerodynamic performances