Assessing the role of anthropogenic and biogenic sources on PM₁ over southern West Africa using aircraft measurements

As part of the Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa (DACCIWA) project, an airborne campaign was designed to measure a large range of atmospheric constituents, focusing on the effect of anthropogenic emissions on regional climate. The presented study details results of the French ATR42 research aircraft, which aimed to characterize gas-phase, aerosol and cloud properties in the region during the field campaign carried out in June/July 2016 in combination with the German Falcon 20 and the British Twin Otter aircraft. The aircraft flight paths covered large areas of Benin, Togo, Ghana and Côte d\u27Ivoire, focusing on emissions from large urban conurbations such as Abidjan, Accra and Lomé, as well as remote continental areas and the Gulf of Guinea. This paper focuses on aerosol particle measurements within the boundary layer (<  2000 m), in particular their sources and chemical composition in view of the complex mix of both biogenic and anthropogenic emissions, based on measurements from a compact time-of-flight aerosol mass spectrometer (C-ToF-AMS) and ancillary instrumentation. Background concentrations (i.e. outside urban plumes) observed from the ATR42 indicate a fairly polluted region during the time of the campaign, with average concentrations of carbon monoxide of 131 ppb, ozone of 32 ppb, and aerosol particle number concentration ( >  15 nm) of 735 cm−3 stp. Regarding submicron aerosol composition (considering non-refractory species and black carbon, BC), organic aerosol (OA) is the most abundant species contributing 53 %, followed by SO4 (27 %), NH4 (11 %), BC (6 %), NO3 (2 %) and minor contribution of Cl (<  0.5 %). Average background PM1 in the region was 5.9 µg m−3 stp. During measurements of urban pollution plumes, mainly focusing on the outflow of Abidjan, Accra and Lomé, pollutants are significantly enhanced (e.g. average concentration of CO of 176 ppb, and aerosol particle number concentration of 6500 cm−3 stp), as well as PM1 concentration (11.9 µg m−3 stp). Two classes of organic aerosols were estimated based on C-ToF-AMS: particulate organic nitrates (pONs) and isoprene epoxydiols secondary organic aerosols (IEPOX–SOA). Both classes are usually associated with the formation of particulate matter through complex interactions of anthropogenic and biogenic sources. During DACCIWA, pONs have a fairly small contribution to OA (around 5 %) and are more associated with long-range transport from central Africa than local formation. Conversely, IEPOX–SOA provides a significant contribution to OA (around 24 and 28 % under background and in-plume conditions). Furthermore, the fractional contribution of IEPOX–SOA is largely unaffected by changes in the aerosol composition (particularly the SO4 concentration), which suggests that IEPOX–SOA concentration is mainly driven by pre-existing aerosol surface, instead of aerosol chemical properties. At times of large in-plume SO4 enhancements (above 5 µg m−3), the fractional contribution of IEPOX–SOA to OA increases above 50 %, suggesting only then a change in the IEPOX–SOA-controlling mechanism. It is important to note that IEPOX–SOA constitutes a lower limit to the contribution of biogenic OA, given that other processes (e.g. non-IEPOX isoprene, monoterpene SOA) are likely in the region. Given the significant contribution to aerosol concentration, it is crucial that such complex biogenic–anthropogenic interactions are taken into account in both present-day and future scenario models of this fast-changing, highly sensitive region

Descentralización de KPMG en Perú hacia la zona norte del país

El presente documento se hizo en base a un análisis efectuado en la región norte del país con la intención de descentralizar y extender los servicios que ofrece KPMG en Lima. Se han realizado estudios sobre cual podría la mejor ubicación para nuestro centro de operaciones, siendo elegida la ciudad de Chiclayo, por ser un punto medio entre Piura y Trujillo. Para poder realizar la inversión necesaria, se hicieron mejorar algunas capacidades financieras de la oficina principal ubicada en la ciudad de Lima mediante el incremento de líneas de crédito o aumento de capital

Fitossociologia comparada da comunidade herbáceo-subarbustiva de restinga em duas geoformações de dunas na planície costeira de Santa Catarina

Dunas são geoformações arenosas produzidas exclusivamente pela ação eólica que se dispõem a partir da região pós-praia. Sobre as dunas desenvolvem-se comunidades vegetais de restinga tipicamente herbáceo-subarbustivas condicionadas pelos fatores ambientais limitantes que influenciam sua organização sociológica. O presente estudo objetivou identificar, por meio do levantamento fitossociológico, possíveis diferenças estruturais entre comunidades instaladas em dois tipos de dunas (frontais e parabólicas). Foi alocado um total de 250 unidades amostrais para caracterização dos parâmetros de cobertura e frequência, absolutas e relativas, e valor de importância das espécies amostradas, além de índices de diversidade e similaridade. Foram levantadas 39 espécies, distribuídas em 37 gêneros e 23 famílias, sendo a maior diversidade observada nas dunas parabólicas e a maior dominância nas dunas frontais, além de certa coocorrência de espécies. As famílias mais ricas em espécies foram Fabaceae, Asteraceae, Poaceae e Cyperaceae. Os resultados obtidos sinalizam que a organização sociológica das comunidades herbáceo-subarbustivas de restinga sobre dunas frontais e parabólicas difere entre si em diversidade, composição e dominância de espécies, as quais devem ser fortemente influenciadas pelas condições ambientais, principalmente pelo vento, que atuam em diferentes níveis sobre essas comunidades. Tais informações podem contribuir com ações de conservação ambiental e da biodiversidade da restinga ante a elevada pressão antrópica na costa catarinense

Review of Describing Early America

In Describing Early America, Pamela Regis argues that the introduction of the Linnaean system in 1735 combined with prevalent cultural beliefs such as the Great Chain of Being to create a new rhetorical paradigm with special implications for natural historians in revolutionary America. Linnaeus\u27s Systema Naturae provided scientists with a portable and immediately applicable method for classifying plants and animals, thus enabling collectors in the field to advance scientific learning directly, without recourse to experts in Europe. In addition to authorizing the American pursuit of science, the Linnaean system added static, noun-based naming procedures to existing verb-oriented narrative practices, enabling natural historians to combine the scientific observation of an unchanging natural order with accounts of their personal experiences as travelers and explorers. This union of cosmic timelessness and contingent personal experience, Regis argues, explains the rhetorical construction of such major eighteenth-century works as Bartram\u27s Travels, Jefferson\u27s Notes on the State of Virginia, and Crévecoeur\u27s Letters from an American Farmer

Evaluation of Bone Heating, Drill Deformation, and Drill Roughness After Implant Osteotomy: Guided Surgery and Classic Drilling Procedure

Purpose: This study evaluated and compared bone heating, drill deformation, and drill roughness after several implant osteotomies in the guided surgery technique and the classic drilling procedure. Materials and Methods: The tibias of 20 rabbits were used. The animals were divided into a guided surgery group (GG) and a control group (CG); subgroups were then designated (G0, G1, G2, G3, and G4, corresponding to drills used 0, 10, 20, 30 and 40 times, respectively). Each animal received 10 sequential osteotomies (5 in each tibia) with each technique. Thermal changes were quantified, drill roughness was measured, and the drills were subjected to scanning electron microscopy. Results: Bone temperature generated by drilling was significantly higher in the GG than in the CG. Drill deformation in the GG and CG increased with drill use, and in the CG a significant difference between GO and groups G3 and G4 was observed. In the GG, a significant difference between GO and all other groups was found. For GG versus CG, a significant difference was found in the 40th osteotomy. Drill roughness in both groups was progressive in accordance with increased use, but there was no statistically significant difference between subgroups or between GG and CG overall. Conclusion: During preparation of implant osteotomies, the guided surgery technique generated a higher bone temperature and deformed drills more than the classic drilling procedure. The increase in tissue temperature was directly proportional to the number of times drills were used, but neither technique generated critical necrosis-inducing temperatures. Drill deformation was directly proportional to the number of times the drills were used. The roughness of the drills was directly proportional to the number of reuses in both groups but tended to be higher in the GG group

Food security and natural resources: diversification strategies

International audienceThis chapter deals with two major issues rural households face in tropical areas: preserving natural resources and guaranteeing food security. Tackling these two challenges simultaneously may require developing profitable production systems that can both guarantee food security for farmers, while also ensuring sustainable management of natural resources

Sécurité alimentaire et ressources naturelles : stratégies de diversification

Voir aussi la version anglaise du livre : Sustainable Food Systems for Food Security. Need for combination of local and global approaches :https://www.quae.com/produit/1787/9782759235766/sustainable-food-systems-for-food-securityInternational audienceCe chapitre traite de deux enjeux majeurs auxquels sont confrontés les ménages ruraux en zone tropicale : préserver les ressources naturelles et assurer la sécurité alimentaire. Relever ces deux défis simultanément requiert de développer des systèmes de production efficaces, capables à la fois de garantir la sécurité alimentaire des agriculteurs et d’assurer une gestion durable des ressources naturelles. Pour ce faire, il convient de s’interroger sur les liens directs et indirects entre la sécurité alimentaire des ménages et la biodiversité à l’échelle de l’exploitation agricole et à celle du paysage

Food security and natural resources: diversification strategies

International audienceThis chapter deals with two major issues rural households face in tropical areas: preserving natural resources and guaranteeing food security. Tackling these two challenges simultaneously may require developing profitable production systems that can both guarantee food security for farmers, while also ensuring sustainable management of natural resources

Food security and natural resources: diversification strategies

International audienceThis chapter deals with two major issues rural households face in tropical areas: preserving natural resources and guaranteeing food security. Tackling these two challenges simultaneously may require developing profitable production systems that can both guarantee food security for farmers, while also ensuring sustainable management of natural resources