263 research outputs found
Managing carbon-intensive materials in a decarbonizing world without a global price on carbon
Emissions from the production of iron and steel could constitute a significant share of a 2°C global emissions budget (around 19% under the IEA 2DS scenario). They need to be reduced, and this could be difficult under nationally based climate policy approaches. We compare a new set of nationally based modelling (the Deep Decarbonization Pathways Project) with best practice and technical limit benchmarks for iron and steel and cement emissions. We find that 2050 emissions from iron and steel and cement production represent an average 0.28 tCO₂ per capita in nationally based modelling results, very close to the technical limit benchmark of 0.21 tCO₂ per capita, and over 2.5 times lower than the best practice benchmark of 0.72 tCO₂ per capita. This suggests that national projections may be overly optimistic about achievable emissions reductions in the absence of global carbon pricing and an international research and development effort to develop low emissions technologies for emissions-intensive products. We also find that equal per capita emissions targets, often the basis of proposals for how global emissions budgets should be allocated, would be inadequate without global emissions trading. These results show that a nationally based global climate policy framework, as has been confirmed in the Paris Agreement, could lead to risks of overshooting global emissions targets for some countries and carbon leakage. Tailored approaches such as border taxes, sectoral emissions trading or carbon taxes, and consumption-based carbon pricing can help, but each faces difficulties. Ultimately, global efforts are needed to improve technology and material efficiency in emissions-intensive commodities manufacturing and use. Those efforts could be supported by technology standards and a globally coordinated R&D effort, and strengthened by the adoption of global emissions budgets for emissions-intensive traded goods
A simplified vortex sheet roll-up method for formation flight
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2004.Includes bibliographical references (p. 105-108).This thesis studies the influence of the roll-up of a wake on the benefits in induced drag and rolling moment experienced by a close formation of two elliptically loaded wings. The roll-up of the leading wake is computed in the Trefftz plane using a linear vorticity panel method. A smoothing parameter as well as a truncation of the vortex sheet in the highly rolled-up areas are introduced in order to stabilize the computations. The trailing wing is simply modeled as a lifting line, and its induced drag is computed thanks to a near-field analysis. The results are compared to computations using simple horseshoe-vortex methods, either with or without a viscous core. Maximum induced drag benefits comprised between 60% and 70% are observed for a lateral overlap of both wings of about 5% to 10% of the span. The maximum rolling moment is in average attained for 1.5% of the span less overlap. It is found that a horseshoe vortex with a viscous core of radius over semi-span ratio (2r[c])/b = 0.12 modeled according to Burnham can account well for the effects of the roll-up of the wake on the benefits in induced drag that can be gained from formation flight. Actually, the difference between both results is mainly confined in a small region around the maximum and the relative error is generally low. Taking the vertical drift of the whole wake into account is not found to be beneficial to the agreement between the results around the maximum. In the case of the rolling moment, the predictions given by simple horseshoe vortex models do not agree very well with the predictions given by the rolled-up sheet model, the relative error between both predictions being very high in many areas.by Amandine Denis.S.M
Design, construction, and test of a reliable, redundant on-board computer (OBC) for the OUFTI-1 CubeSat of the University of Li`ege
Peer reviewe
Software architecture for the automatization of the ground segment of the OUFTI-1 CubeSat
OUFTI-1 nanosatellit
Design and implementation of a strategy for handling the telecommands and telemetries of the nanosatellite OUFTI-1
peer reviewedaudience: researcher, professional, student, popularization, otherOUFTI-1 nanosatellit
Status of electrical power supply of OUFTI-1 nanosatellite as of mid-2012: design, implementation, and tests
We describe the principles and performances the OUFTI-1 nanosatellite electrical power supply (EPS), which is designed to provide subsystems with the required voltages and currents, with as high a reliability as possible.OUFTI-1 nanosatellit
Fontenu – Chalain, station 19
Identifiant de l'opération archéologique : 3923005 Date de l'opération : 1999 (FP) Comme dans la plupart des habitats néolithiques littoraux au nord-ouest des Alpes, le village de Chalain 19, occupé à deux reprises à la fin du IVe millénaire, a été construit sur une presqu’île de la beine lacustre, loin de la terre ferme et du bas marais. Cette position, avec le lac d’un côté et une plateforme de craie lacustre de faible résistance mécanique de l’autre, répond très clairement à une mise en dé..
The rhizosphere microbiota of the zinc and cadmium hyperaccumulators Arabidopsis halleri and Noccaea caerulescens is highly convergent in Prayon (Belgium)
The Prayon site is known as a zinc-polluted area where two zinc and cadmium hyperaccumulator plant species currently coexist, although Arabidopsis halleri was introduced more recently than Noccaea caerulescens . While soil microorganisms may influence metal uptake, the microbial community present in the rhizosphere of hyperaccumulators remains poorly known. Plants of both species were sampled with their bulk and rhizosphere soil from different plots of the Prayon site. Soil components (ionome, pH, water composition, temperature) were analyzed, as well as shoot ionome and expression levels of metal transporter genes ( HMA3 , HMA4 , ZIP4 / ZNT1 , ZIP6 , MTP1 ). The taxonomic diversity of the microorganisms in soil samples was then determined by 16S rRNA metabarcoding and compared at the Operational Taxonomy Unit (OTU) level and across different taxonomic levels. Our elemental analyses confirmed that the site is still highly contaminated with zinc and cadmium and that both plant species indeed hyperaccumulate these elements in situ . Although the pollution is overall high, it is heterogenous at the site scale and correlates with the expression of some metal transporter genes. Metabarcoding analyses revealed a decreasing gradient of microbial diversity, with more OTUs discovered in the rhizosphere than in the soil bulk, especially at the bottom of the cores. However, the variability gradient increases with the distance from roots. Using an ad hoc pseudo-taxonomy to bypass the biases caused by a high proportion of unclassified and unknown OTUs, we identified Chloroflexi, Armatimonadetes, Pirellulaceae, Gemmatimonadetes and Chitinophagaceae as the drivers of the differences in the gradient along the cores. In contrast, no significant difference was identified between the rhizosphere composition of A. halleri and N. caerulescens . This suggests that, despite their distinct colonization history in Prayon, the two plant species have now recruited highly convergent microbial communities in the rhizosphere
Selective inhibition of GluN2D-containing N-methyl-D-aspartate receptors prevents tissue plasminogen activator-promoted neurotoxicity both in vitro and in vivo
BACKGROUND: Tissue plasminogen activator (tPA) exerts multiple functions in the central nervous system, depending on the partner with which it interacts. In particular, tPA acts as a positive neuromodulator of N-methyl-D-aspartate glutamatergic receptors (NMDAR). At the molecular level, it has been proposed that the pro-neurotoxicity mediated by tPA might occur through extrasynaptic NMDAR containing the GluN2D subunit. Thus, selective antagonists targeting tPA/GluN2D-containing NMDAR signaling would be of interest to prevent noxious effects of tPA. RESULTS: Here, we compared three putative antagonists of GluN2D-containing NMDAR and we showed that the new compound UBP145 ((2R*,3S*)-1-(9-bromophenan-threne-3-carbonyl)piperazine-2,3-dicarboxylic acid) is far more selective for GluN2D subunits than memantine and PPDA (phenanthrene derivative (2S*, 3R*)-1-(phenanthrene-2-carbonyl)piperazine-2,3-dicarboxylic acid). Indeed, in vitro, in contrast to the two other compounds, UBP145 prevented NMDA toxicity only in neurons expressing GluN2D (ie, in cortical but not hippocampal neurons). Furthermore, in cultured cortical neurons, UBP145 fully prevented the pro-excitotoxic effect of tPA. In vivo, we showed that UBP145 potently prevented the noxious action of exogenous tPA on excitotoxic damages. Moreover, in a thrombotic stroke model in mice, administration of UBP145 prevented the deleterious effect of late thrombolysis by tPA. CONCLUSIONS: In conclusion, tPA exerts noxious effects on neurons by acting on GluN2D-containing NMDAR and pharmacological antagonists of GluN2D-containing NMDAR could be used to prevent the ability of tPA to promote neurotoxicity
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