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Missions chrétiennes en Afrique sous domination coloniale
No full textGeneral overview of the history of religious misions in colonial Africa and their interactions with colonial regimes
Tropospheric nitrogen dioxide levels vary diurnally in Asian cities
Full text linkSatellite measurements of nitrogen dioxide have been used to infer nitrogen oxide emissions, a critical component in tropospheric chemistry and pollution. New observations from the Geostationary Environmental Monitoring Spectrometer offer a breakthrough by providing a daytime record of nitrogen dioxide over Asia. Here we present the summertime diurnal patterns of nitrogen dioxide at major cities, power plant regions, and the Strait of Malacca. The Geostationary Environmental Monitoring Spectrometer data across various regions show high nitrogen dioxide in the morning which decrease in the afternoon, with varying hourly peaks, troughs, and amplitudes reflecting diurnal characteristics of local emissions and chemistry. Nitrogen oxide emissions inferred from Geostationary Environmental Monitoring Spectrometer and the Weather Research and Forecasting model coupled with Chemistry also show distinct patterns among regions: early morning peaks occur over Hanoi, Guangzhou, and Bangkok; mid-to-late morning peaks appear over Seoul and Beijing; and late afternoon peaks are noted in the Yangtze River Delta region. Top-down emissions incorporating temporal changes in the Geostationary Environmental Monitoring Spectrometer nitrogen dioxide yield the most accurate nitrogen dioxide simulations
First-principles Measurement of Ion and Electron Energization in Collisionless Accretion Flows
Full text linkWe present the largest 3D particle-in-cell shearing-box simulations of turbulence driven by the magnetorotational instability, for the first time employing the realistic proton-to-electron mass ratio. We investigate the energy partition between relativistically hot electrons and subrelativistic ions in turbulent accreting plasma, a regime relevant to collisionless, radiatively inefficient accretion flows around supermassive black holes such as those targeted by the Event Horizon Telescope. We provide a simple empirical formula to describe the measured heating ratio between ions and electrons, which can be used for more accurate global modeling of accretion flows with standard fluid approaches such as general-relativistic magnetohydrodynamics
Description of a new endemic <i>Enteromius</i> (Teleostei: Cyprinidae) from the upper Malagarazi in Burundi: Lessons for a protected area under implementation
No full textRecent collecting efforts in the upper Malagarazi basin (2013 2022) allowed for an integrative study based on qualitative (colour), quantitative (meristic and metric), and barcoding gene [mtDNA, cytochrome c oxidase (COI)] data of specimens similar to Enteromius sp. ascutelatus , being a previously identified, potentially, new species. Based on these data, the present study confirms its identification as a new species for science, which is here formally described as Enteromius nzigidaherai sp. nov. This new species belongs to the group of Enteromius species for which the last unbranched ray of the dorsal fin is flexible and devoid of serrations along its posterior edge. This species has a horizontal series of black spots at the midlateral level of the sides. Three congeneric species, known from the Congo basin sensu lato, with two of them also found in the upper Malagarazi basin, are most similar to it. However, E. nzigidaherai sp. nov. is distinguished from the two sympatric upper Malagarazi species, that is, E. quadrilineatus and E. lineomaculatus, at least by two meristics and two morphometrics. It is also distinguished from E. urostigma, known from the upper Congo basin, by two meristics and one, apparently related, morphometric. In addition, a barcoding (mtDNA, COI) study revealed that the specimens of E. nzigidaherai sp. nov. form a well-supported, separate lineage, with a K2P genetic distance of more than 10% with specimens identified as E. quadrilineatus and E. lineomaculatus, both originating from the upper Malagarazi basin and for which tissue samples were available. Finally, the new species was found to be endemic to the upper reaches of two left bank affluents of the upper Malagarazi basin: the Muyovozi and the Kinwa. However, both affluents are threatened by human activities, which seem to have resulted in its local disappearance as recent intensive collecting efforts in the latter affluent have remained unsuccessful. The species should thus be considered Critically Endangered (CR) according to IUCN criteria B1ab(ii,iv)c(i,iii). Therefore, it is hoped that the present description draws renewed attention to the importance of aquatic protection in the region by highlighting the need for the effective establishment of the Malagarazi Nature Reserve and concern for its optimal delimitation to efficiently protect the entire ichthyofauna of the upper Malagarazi, without excluding the fish species confined to its affluent rivers
Where do core thalamocortical axons terminate in mammalian neocortex when there is no cytoarchitecturally distinct layer 4?
No full textUnravelling the carbon cycle at the tree and forest scale : a TREE4FLUX initiative in Central African Tropical Forests
Full text linkTropical forests play an essential role in the carbon cycle. However, climate change threatens their ability to store carbon. Specifically, understanding the perturbation of climatic regimes on carbon uptake mechanisms is crucial. However, our knowledge concerning the spatial and temporal carbon distribution over trees and forests is limited, especially in the context of tropical forests of Central Africa. The TREE4FLUX project aims to fill these gaps for the first time in the forests of Congo Basin forests, by focusing research at different scales around the CongoFlux tower in the Yangambi Biosphere Reserve (DRC). On the forest ecosystem scale, carbon uptake can be monitored by measurements of CO2 exchanges between the atmosphere and the vegetation using the Eddy Covariance approach. Carbon assessments are also possible through tree-growth measurements within a network of permanent inventory plots. However, refining the carbon cycle at the tree scale requires a detailed study of the numerous inextricable metabolic processes that underlie tree growth, e.g. photosynthesis, wood formation, or respiration. Because they are largely controlled by various climatic drivers, climate-growth relationships over time remain hard to establish. The chronology of carbon uptake and attribution to the different mechanisms remain elusive preventing a grasp of the intra-annual variations of these periodic processes and their articulation over time. This is the case of xylogenesis or wood formation in which each phase is differently involved in the carbon cycle and sensitive to various climatic drivers. To understand the sensitivity of tree growth to climate, we need to untangle the cambium s role in wood formation. For that purpose, monitoring cambial phenology helps characterize the distribution, allocation, and short- and long-term carbon storage in woody material. While tree growth uptakes carbon, respiration releases carbon into the atmosphere at various levels. Heterotrophic and autotrophic respirations have a decisive role in the carbon cycle at the forest scale but face significant misunderstandings in this regard. To upscale our understanding from individual tree to forest scale, we imperatively need respiration monitoring in both living and decayed trees. This requires unravelling the metabolic processes driving both autotrophic and heterotrophic respiration, i.e. the tree growth and decayed process, respectively. Characterization of carbon fluxes according to an integrative approach over climatic variations is required to understand how environmental changes affect ecosystem dynamics and their ability to provide ecosystem services
Boat models from the Early Dynastic settlement of Elkab: New insights on the archaeology of early pharaonic domestic contexts
No full textSince 2009 the excavations of the Royal Museums of Art and History (Brussels) at the Upper Egyptian site of Elkab have continued to reveal the origins and dynamic development of this provincial town site. From a small community with a subsistence economy that was primarily based on farming and fishing in the Predynastic period, it expanded and developed from the Early Dynastic period onwards into a fully urbanised society. During the excavation of several well-dated 2nd Dynasty domestic house contexts, six
fragmentary boat models were discovered. These small objects raise interesting questions regarding daily life in a provincial settlement at the onset of the 3rd millennium BCE. Boat models are indeed well known from funerary or cultic spheres, but few of them have been discovered in a settlement context. Like anthropomorphic and zoomorphic statuettes, they are generally considered to be ex-votos and their presence inside settlements allows us to reconsider the evolution and functions of these remarkable objects
La sculpture baroque dans les Pays-Bas méridionaux et la principauté de Liège = Barokke beeldhouwkunst in de Zuidelijke Nederlanden et het prinsbisdom Luik
No full textKunsthistorisch seminarie van het KIK, nr 1, Brussel, 25/02/2000Séminaire d’histoire de l’art de l’IRPA n° 1, Bruxelles, 25/02/2000
Seasonality of tree growth and carbon uptake through assessments of the cambial phenology in the Biosphere Reserve of Yangambi in the Democratic Republic of the Congo
No full textTropical forests play a significant role in the global carbon cycle. The carbon is taken up through the xylogenesis, a key mechanism resulting from the division, differentiation, and lignification of tree cells in the cambial zone. This periodic process depends on environmental and genetic drivers that influence wood structure and anatomy. Yet patterns of seasonal cambial growth remain poorly understood for tropical forests, especially for those experiencing low seasonality. However, detailed information on the xylogenesis complements assessments of radial growth, measured through on-the-ground inventories, and the quantification of ecosystem carbon sinks and sources, assessed by eddy-covariance sensors. This is gaining relevance in the context of Congo Basin forests, because of the operationalization of the first flux tower (Congoflux) in semi-deciduous African forests and the increasing number of classic, intensive, and large-scale permanent inventory plots. Cambial phenology monitoring is therefore mandatory to link effective tree growth and permanent carbon sequestration. To meet this goal, we first need to better understand the tree growth cycles. For this purpose, we monitored the cambial phenology of six representative species of Yangambi forests (Democratic Republic of Congo) over the seasonal transition for which we suppose the onset of cambial activity. We characterized the cambial phenology among and within species through a study of the cells and tissues in the cambial zone over time. The description of xylogenesis phases over climatic variations is required to grasp how environmental changes affect ecosystem dynamics and their ability to provide ecosystem services. Studying the cambial phenology is therefore essential for a better understanding of the carbon cycle in a forest ecosystem