International Journal of Agricultural Research, Innovation and Technology (IJARIT)
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Upsilococconeis dapalistriata gen. nov. & comb. nov. (Bacillariophyta)a pantropical marine member of Cocconeidaceae
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Insights into tropical cloud chemistry in Réunion (Indian Ocean): results from the BIO-MAÏDO campaign
No full textInternational audienceAbstract. We present here the results obtained during an intensive field campaign conducted in the framework of the French “BIO-MAÏDO” (Bio-physico-chemistry of tropical clouds at Maïdo (Réunion Island): processes and impacts on secondary organic aerosols' formation) project. This study integrates an exhaustive chemical and microphysical characterization of cloud water obtained in March–April 2019 in Réunion (Indian Ocean). Fourteen cloud samples have been collected along the slope of this mountainous island. Comprehensive chemical characterization of these samples is performed, including inorganic ions, metals, oxidants, and organic matter (organic acids, sugars, amino acids, carbonyls, and low-solubility volatile organic compounds, VOCs). Cloud water presents high molecular complexity with elevated water-soluble organic matter content partly modulated by microphysical cloud properties. As expected, our findings show the presence of compounds of marine origin in cloud water samples (e.g. chloride, sodium) demonstrating ocean–cloud exchanges. Indeed, Na+ and Cl− dominate the inorganic composition contributing to 30 % and 27 %, respectively, to the average total ion content. The strong correlations between these species (r2 = 0.87, p value: < 0.0001) suggest similar air mass origins. However, the average molar Cl-/Na+ ratio (0.85) is lower than the sea-salt one, reflecting a chloride depletion possibly associated with strong acids such as HNO3 and H2SO4. Additionally, the non-sea-salt fraction of sulfate varies between 38 % and 91 %, indicating the presence of other sources. Also, the presence of amino acids and for the first time in cloud waters of sugars clearly indicates that biological activities contribute to the cloud water chemical composition. A significant variability between events is observed in the dissolved organic content (25.5 ± 18.4 mg C L−1), with levels reaching up to 62 mg C L−1. This variability was not similar for all the measured compounds, suggesting the presence of dissimilar emission sources or production mechanisms. For that, a statistical analysis is performed based on back-trajectory calculations using the CAT (Computing Atmospheric Trajectory Tool) model associated with the land cover registry. These investigations reveal that air mass origins and microphysical variables do not fully explain the variability observed in cloud chemical composition, highlighting the complexity of emission sources, multiphasic transfer, and chemical processing in clouds. Even though a minor contribution of VOCs (oxygenated and low-solubility VOCs) to the total dissolved organic carbon (DOC) (0.62 % and 0.06 %, respectively) has been observed, significant levels of biogenic VOC (20 to 180 nmol L−1) were detected in the aqueous phase, indicating the cloud-terrestrial vegetation exchange. Cloud scavenging of VOCs is assessed by measurements obtained in both the gas and aqueous phases and deduced experimental gas-/aqueous-phase partitioning was compared with Henry's law equilibrium to evaluate potential supersaturation or unsaturation conditions. The evaluation reveals the supersaturation of low-solubility VOCs from both natural and anthropogenic sources. Our results depict even higher supersaturation of terpenoids, evidencing a deviation from thermodynamically expected partitioning in the aqueous-phase chemistry in this highly impacted tropical area
Organic inputs in agroforestry systems improve soil organic carbon storage in Itasy, Madagascar
No full textTopical Collection on Regional management practices with positive effects on soil carbon to meet the goals of the 4p1000 initiative 1000International audienceAgroforestry systems (AFS) are recognized as one of the practices with high potential to store carbon in soils. In the Itasy region, AFS were introduced to improve farmers' livelihoods by diversifying income sources and to address problems related to soil degradation. Previous studies in the region have shown the potential of AFS to store organic carbon in the soil. In the present work, we carried out further studies to assess the main factors affecting SOC stocks in AFS. In 2014, we performed a soil sampling on 137 AFS farmers'plots to assess SOC stocks in different AFS. In 2018, a second sampling was carried out to calculate SOC storage rates using the diachronic approach on 30 most representative AFS. The results revealed that the factors "age of the system" and "type of organic inputs" significantly affected SOC stocks in AFS. SOC stocks increased significantly over time in AFS plots, benefiting from regular organic inputs such as manure and/or compost. In contrast, SOC stocks remained unchanged over time in AFS plots where no organic fertilization was used. Our study showed a substantial SOC storage up to 47 parts per thousand year(-1), mainly explained by regular additions of organic inputs to maintain soil fertility and crop production. However, to fully understand the process of SOC storage in this context, further works, such as the analysis of the link between organic matter quality and the SOC storage process, and the quantification of the share of soil carbon inputs derived from tree biomass should be undertaken
Topology Optimization for Steady-state anisothermal flow targeting solid with piecewise constant thermal diffusivity
No full textInternational audienceSeveral engineering problems result in a PDE-constrained optimization problem that aims at finding the shape of a solid inside a fluid which minimizes a given cost function. These problems are categorized as Topology Optimization (TO) problems. In order to tackle these problems, the solid may be located with a penalization term added in the constraints equations that vanishes in fluid regions and becomes large in solid regions. This paper addresses a TO problem for anisothermal flows modelled by the steady-state incompressible Navier-Stokessystem coupled to an energy equation, with mixed boundary conditions, under the Boussinesq approximation. We first prove the existence and uniqueness of a solution to these equations as well as the convergence of its finite element discretization. Next, we show that our TO problem has at least one optimal solution for cost functions that satisfy general assumptions. The convergence of discrete optimum toward the continuous one is then proved as well as necessary first order optimality conditions. Eventually, all these results let us design a numerical algorithm to solve a TO problem approximating solids with piecewise constant thermal diffusivities also refered as multi-materials. A physical problem solved numericallyfor varying parameters concludes this paper
Correlating sulfur solubility with short-to-intermediate-range ordering in the structure of borosilicate glasses
No full textInternational audienceThe present study focuses on understanding the structural dependence of sulfur (as SO3) solubility in Na2O–B2O3–SiO2 glasses over a broad composition space exhibiting a rich variety of structural associations. The focus is on probing the impact of the (1) structural role of Na+, (2) degree of polymerization, and (3) network former connectivity (formation of Si–O–B and B–O–B linkages) on sulfur solubility in borosilicate glasses. By employing a suite of state-of-the-art characterization techniques, including inductively coupled plasma-optical emission spectroscopy (ICP-OES), magic-angle spinning (MAS) NMR spectroscopy, and Raman spectroscopy, an inverse correlation has been established between the sulfur solubility and the degree of network polymerization in the glasses across the investigated composition space. While the modification of SO3 leading to the formation of SO42– can successfully compete with the network depolymerization mechanisms (i.e., creation of nonbridging oxygens) and induce repolymerization in the glass network, the BO3 → BO4 conversion facilitated by the charge compensation by alkali cations takes precedence. The results from this study, when extended to more complex borosilicate-based glass compositions, will not only add to our understanding of the fundamental science controlling the sulfur solubility in borosilicate-based real-world nuclear waste glasses but will also form a basis for the development of nonempirical quantitative structure–property relationship (QSPR)-based predictive models
The scientific observation campaign of the Hayabusa-2 capsule re-entry
No full textInternational audienceOn 2020 December 5 at 17:28 UTC, the Japan Aerospace Exploration Agency's Hayabusa-2 sample return capsule came back to the Earth. It re-entered the atmosphere over South Australia, visible for 53 seconds as a fireball from near the Northern Territory border toward Woomera where it landed in the the Woomera military test range. A scientific observation campaign was planned to observe the optical, seismo-acoustic, radio, and high energy particle phenomena associated with the entry of an interplanetary object. A multi-institutional collaboration between Australian and Japanese universities resulted in the deployment of 49 instruments, with a further 13 permanent observation sites. The campaign successfully recorded optical, seismo-acoustic, and spectral data for this event which will allow an in-depth analysis of the effects produced by interplanetary objects impacting the Earth's atmosphere. This will allow future comparison and insights to be made with natural meteoroid objects
Life history parameters and predation capacities of Nesidiocoris volucer: a new biological control agent for tomato crop
No full textInternational audienceWhiteflies are one of the major pests of tomato under greenhouses, and their control partly relies on biocontrol strategies. Among those biocontrol agents, parasitoids or predators are widely used. However, the introduction of a biocontrol agent in a new area is not trivial. For that reason, we investigated the use of a tropical native mirid, Nesidiocoris volucer (Hemiptera: Miridae), for the biological control of whiteflies among other insect pests on tomato crops under greenhouses in the subtropical island of La Réunion, France. Nesidiocoris volucer life history traits and plant injury were examined. Nymphs developed and survived between 15 and 30°C and required on average 49.41 days at 15°C and on average 10.50 days at 30°C to develop (nymph survival >94%). At 25°C, each female produced on average 65 eggs. Nesidiocoris volucer was able to feed on several prey species, but performed better on whiteflies than on spider mites or thrips. No N. volucer feeding injury was observed on tomato. Nesidiocoris volucer has also been found in tropical countries of Africa, and we believe that the data presented on this natural enemy could be of great importance for the biocontrol of whiteflies in tropical areas
Scenario modelling of carbon mineralization in 3D soil architecture at the microscale: Toward an accessibility coefficient of organic matter for bacteria
No full textInternational audienceThe microscale physical characteristics of microbial habitats considerably affect the decomposition of organic matter in soils. One of the challenges is to identify microheterogeneities in soil that can explain the extent of carbon mineralization. The aim of this study was therefore to identify descriptors of mu m-scale soil heterogeneity that can explain CO2 fluxes obtained at the mm scale. A suite of methods and models that visualize soil heterogeneity at scales relevant to microorganisms has been developed over the last decade. Among the existing 3D models that simulate microbial activity in soils, Mosaic is able to simulate, within a short computation time, the microbial degradation of organic matter at the microhabitat scale in soil using real 3D images of soil porosity. Our approach was to generate scenarios of carbon mineralization for various microscale environmental conditions and determine how the descriptors of soil structure could explain CO2 evolution. First, we verified that the simulated diffusion of solutes in the soil samples obtained with Mosaic were the same as those obtained using the same parameter set from a robust 3D model based on a lattice Boltzmann approach. Then, we ran scenarios considering different soil pore architectures, water saturations and microorganism and organic matter placements. We found that the CO2 emissions simulated for the different scenarios could be explained by the distance between microorganisms and organic matter, the diffusion of the substrate and the concentration of the available substrate. For some of the scenarios, we proposed a descriptor of accessibility based on the geodesic distance between microorganisms and organic matter weighted by the amount of organic matter. This microscale descriptor is correlated to the simulated CO2 flux with a correlation coefficient of 0.69. Highlights Does the microscopic soil organisation explain the macroscopic mineralisation fluxes ? We present a new descriptor based on the geodesic distances between organic matter and microorganisms. We found a correlation between the descriptor of mu m-heterogeneity and the mineralization fluxes. Other scenarios should be carried out under wider environmental mu m-conditions to confirm our results
Combining audio and visual displays to highlight temporal and spatial seismic patterns
No full textData availability all datasets used in this study are available on the web at the following addresses (see also the manuscript):- https://www.usgs.gov/volcanoes/kilauea/monitoring- https://www.usgs.gov/observatories/hawaiian-volcano-observatory- https://pnsn.org/seismograms- https://www.pnsn.org/tremor- http://www.fdsn.org/networks/detail/Y4_2014.International audienceData visualization, and to a lesser extent data sonification, are classic tools to the scientific community. However, these two approaches are very rarely combined, although they are highly complementary: our visual system is good at recognizing spatial patterns, whereas our auditory system is better tuned for temporal patterns. In this article, data representation methods are proposed that combine visualization, sonification, and spatial audio techniques, in order to optimize the user’s perception of spatial and temporal patterns in a single display, to increase the feeling of immersion, and to take advantage of multimodal integration mechanisms. Three seismic data sets are used to illustrate the methods, covering different physical phenomena, time scales, spatial distributions, and spatio-temporal dynamics. The methods are adapted to the specificities of each data set, and to the amount of information that the designer wants to display. This leads to further developments, namely the use of audification with two time scales, the switch from pure audification to time-modulated noise, and the switch from pure audification to sonic icons. First user feedback from live demonstrations indicates that the methods presented in this article seem to enhance the perception of spatio-temporal patterns, which is a key parameter to the understanding of seismically active systems, and a step towards apprehending the processes that drive this activity
Le Droit agricole, forestier, alimentaire et pastoral congolais: Etude de quelques aspects du droit de l’environnement
No full textInternational audienceCet ouvrage de droit forestier et de législation agro-alimentaire et pastorale permet de cerner les tenants et les aboutissants de ces deux branches du droit public qui font partie intégrante du droit de l’environnement et du droit économique dont ils sont des émanations visibles. Ces branches du droit qui permettent à l'individu de vivre sainement et en toute sécurité, concourent à la protection de l'espèce humaine ainsi qu'à son auto-entretien