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Pesticides use in gardening areas in Burkina Faso and evaluation of the resulting risk for the operator using the new AOEM proposed by EFSA guidelines
No full textPesticides are widely used in gardening to maintain high yield, prevent diseases and control pests and rodents. Field surveys conducted in Burkina Faso have underlined the lack of knowledge regarding good agricultural practices and the use of unsuitable and obsolete pesticides. Improper packaging and high illiteracy rate in rural areas also hamper the compliance with recommended doses, application rates and safety measures provided on original manufacturer’s labels. Pesticides operators are persons who mix, load and apply the pesticides. These phases are critical and present great risks in terms of pesticide exposure. In practice, exposure will be influenced by specific conditions under which pesticides are handled (packaging, environmental conditions, personal protective equipment, etc.). Because of their work, operators are subject to receive the greatest exposure which put them at higher risk for acute intoxication but also long term adverse health effects. The present study aims at assessing occupational exposure to pesticides in gardening areas and to develop a database of pesticides use in Burkina Faso. Many predictive models have been used in other areas to estimate operator exposure. In 2014, the EFSA (European Food Safety Authority) Panel on Plant Protection and their Residues proposed a new guidance document that supports the use of a new predictive agricultural operator exposure model (AOEM) based on a statistical analysis of exposure studies conducted between 1999 and 2009. In order to supply the model with specific local data, a survey have been conducted on 460 gardeners located in four gardening areas. The questionnaires aimed at identifying culture types, agricultural practices (crop calendar, watering, etc.), pesticides use (type, quantity, frequency of application, equipment used, environmental conditions, etc.) and observed intoxication symptoms. Two complementary surveys directed toward pesticides resellers (n=25) and health care centers (n=20) have been conducted to identify pesticides available on local market and recorded intoxication cases.76 % of the quantity applied exceed the doses recommended by the manufacturer. 50% of gardeners wear no personal protective equipment (PPE) and 37% only a muffler in synthetic fabric. Two scenarios have been evaluated for acute and chronic risk: Current agricultural practices (S1) and Use of appropriate PPE (S2). The acute and chronic risk indexes exceed the unity for respectively 75% and 17% of the cases in S1 indicating that the acceptable operator exposure levels (Acute Reference Dose (ARfD) and Acceptable Operator Exposure Level (AOEL)) were exceeded. The risk index under the unity for nearly 98% of the cases in S2 indicates that the lack of proper PPE increases exposure inducing unacceptable acute and long term risks for the operator. As the knapsack model is not dependent on pesticide dose, this study underlines that availability of suitable PPE and training of the pesticides operators would drastically improve the situation.GR-CE
Habiter en ville
No full textSAR-DCote: 1994.043Archive: MEM.1/1A4 horizontalGroupe de suivi: Bevilacqua Mario; Zurbuchen Bernard; Schudel Barbar
Mitochondrial DNA Analyses Indicate High Diversity, Expansive Population Growth and High Genetic Connectivity of Vent Copepods (Dirivultidae) across Different Oceans
No full textCommunities in spatially fragmented deep-sea hydrothermal vents rich in polymetallic sulfides could soon face major disturbance events due to deep-sea mineral mining, such that unraveling patterns of gene flow between hydrothermal vent populations will be an important step in the development of conservation policies. Indeed, the time required by deep-sea populations to recover following habitat perturbations depends both on the direction of gene flow and the number of migrants available for re-colonization after disturbance. In this study we compare nine dirivultid copepod species across various geological settings. We analyze partial nucleotide sequences of the mtCOI gene and use divergence estimates (F-ST) and haplotype networks to infer intraspecific population connectivity between vent sites. Furthermore, we evaluate contrasting scenarios of demographic population expansion/decline versus constant population size (using, for example, Tajima's D). Our results indicate high diversity, population expansion and high connectivity of all copepod populations in all oceans. For example, haplotype diversity values range from 0.89 to 1 and F-ST values range from 0.001 to 0.11 for Stygiopontius species from the Central Indian Ridge, Mid Atlantic Ridge, East Pacific Rise, and Eastern Lau Spreading Center. We suggest that great abundance and high site occupancy by these species favor high genetic diversity. Two scenarios both showed similarly high connectivity: fast spreading centers with little distance between vent fields and slow spreading centers with greater distance between fields. This unexpected result may be due to some distinct frequency of natural disturbance events, or to aspects of individual life histories that affect realized rates of dispersal. However, our statistical performance analyses showed that at least 100 genomic regions should be sequenced to ensure accurate estimates of migration rate. Our demography parameters demonstrate that dirivultid populations are generally large and continuously undergoing population growth. Benthic and pelagic species abundance data support these findings.IBI-S
Crystal structures of eight mono-methyl alkanes (C-26-C-32) via single-crystal and powder diffraction and DFT-D optimization
No full textThe crystal structures of eight mono-methyl alkanes have been determined from single-crystal or high-resolution powder X-ray diffraction using synchrotron radiation. Mono-methyl alkanes can be found on the cuticles of insects and are believed to act as recognition pheromones in some social species, e.g. ants, wasps etc. The molecules were synthesized as pure S enantiomers and are (S)-9-methylpentacosane, C26H54; (S)-9-methylheptacosane and (S)-11-methylheptacosane, C28H58; (S)-7-methylnonacosane, (S)-9-methylnonacosane, (S)-11-methylnonacosane and (S)-13-methylnonacosane, C30H62; and (S)-9-methylhentriacontane, C32H66. All crystallize in space group P2(1). Depending on the position of the methyl group on the carbon chain, two packing schemes are observed, in which the molecules pack together hexagonally as linear rods with terminal and side methyl groups clustering to form distinct motifs. Carbon-chain torsion angles deviate by less than 10 degrees from the fully extended conformation, but with one packing form showing greater curvature than the other near the position of the methyl side group. The crystal structures are optimized by dispersion-corrected DFT calculations, because of the difficulties in refining accurate structural parameters from powder diffraction data from relatively poorly crystalline materials.LQ
Second harmonic scattering of nanoparticles: A journey into the electrical double layer
No full textIn aqueous solutions, a charged surface causes the redistribution of nearby ions. The ion layers formed are known as the electrical double layer (EDL), and are widespread in many systems involving electrochemistry, colloidal science, biomedicine, and energy storage. Over the centuries, models have been developed to describe the structure of the EDL, including the Helmholtz, Gouy-Chapman, and Gouy-Chapman-Stern models. While these models have given fairly accurate descriptions, they have limitations in depicting the structure of the EDL at the molecular level.
In this thesis, we focus on the EDL of colloidal silica nanoparticles, not only because of the wide applications of silica nanoparticles in drug delivery, cosmetics, food additives, etc, but also because of their high stability and tunable sizes. We employ angle-resolved second harmonic scattering (AR-SHS), a label-free nonlinear optical method, to characterize the EDL around silica colloidal nanoparticles. AR-SHS is a highly sensitive tool providing information on two interfacial properties: Surface potential Phi0 and interfacial water orientation Chi2.
We first calculate the size dependence of the surface and electrostatic geometric form factor functions for nonlinear scattering, together with their relative contribution to the AR-SHS patterns. This theoretical part gives an insight into the scattering efficiency of NPs of different sizes. We then show to which extent the SH signal of different particle sizes is modulated by the material's surface properties and the composition of the aqueous environment. Finally, we propose a scheme to predict the dominating optical response (whether the surface or electrostatic) as a function of particle size. Our work establishes a quantified connection between experimental AR-SHS patterns and the material's surface properties of the particle.
We then explore the evolution of the EDL thickness with the increase of ionic concentration using AR-SHS. Following previous work in our group, we characterize the behavior of the EDL at salt concentrations below the millimolar range, including inner-sphere adsorption, diffuse layer formation, and outer-sphere adsorption. Moreover, we show for the first time that, by appropriately selecting the nanoparticle size, it is possible to retrieve information also in the millimolar range. In this range, a decrease in Ί_0 is observed, suggesting a compression in the EDL thickness. Molecular dynamics simulations show that the EDL compression is primarily due to the compression of the diffuse layer rather than that of the Stern plane.
Finally, we examine the influence of the EDL ion distribution on the AR-SHS signal. We derive the scattering form factors for the electrostatic response for five different ion distributions, each representing a different electrostatic potential decay in the EDL. Using the same ion distributions, we then calculate the integrated AR-SHS intensities and extract the surface parameters Phi0 and Chi2 through fitting of the AR-SHS data. The results indicate that, although there are deviations amongst the different electric potential functions, the trends of Phi0 and Chi2 extracted can be captured successfully irrespective of the ion distribution. The study successfully demonstrates the universality of the AR-SHS approach to establish a molecular-level picture of the EDL.LB
A review of modeling the effects of vegetation on large wood recruitment processes in mountain catchments
No full textLarge wood (LW) is an important element in riparian and mountain ecosystems and influences geomorphic controls, particularly in torrents and mountain rivers. Despite several advantages, LW can also exacerbate flood damage near infrastructure due to logjams or backwater rise and is often treated as a potential hazard. In an attempt to reduce such problems, channel slopes and banks are often clear cut in practice. This leads to a debate between the opinions of different scientists as well as stream and forest managers, where it is difficult to find a compromise between optimizing risk mitigation and eco-morphological functionality. Regarding risk mitigation due to LW, situations where the positive effects of vegetation succumb to negative effects should be identified to distinguish if shrubs or small trees (DBH 10 cm) have the potential to reduce the magnitude and frequency of recruitment processes, practices for forest management need to be optimized. Based on literature research, this article summarizes state of the art knowledge of vegetation effects on LW recruitment processes. In doing so, it focuses on three main recruitment processes: hydraulic bank erosion, geotechnical bank erosion and hillslope failure. Hydraulic bank erosion is responsible for delivering high volumes of sediment as well as LW in mountain catchments by removing streambank material through excess shear stress. The positive effects of vegetation can be quantified and implemented in modeling approaches through the adjustment of discharge-specific resistance coefficients or by using stochastic approaches. Geotechnical bank erosion and hillslope failure contribute to LW recruitment through failure. Root reinforcement is predominately the most important effect on how vegetation stabilizes streambanks and hillslopes. Based on the information mentioned above, a flow chart was formulated that uses specific criteria to define conditions in which forest management should be performed to mitigate potential LW recruitment without drastically removing all trees.PL-LC
Characterization of reliability of spike timing in spinal interneurons during oscillating inputs
No full textThe spike timing in rhythmically active interneurons in the mammalian spinal locomotor network varies from cycle to cycle. We tested the contribution from passive membrane properties to this variable firing pattern, by measuring the reliability of spike timing, P, in interneurons in the isolated neonatal rat spinal cord, using intracellular injection of sinusoidal command currents of different frequencies (0.325-31.25 Hz). P is a measure of the precision of spike timing. In general, P was low at low frequencies and amplitudes (P = 0-0.6; 0-1.875 Hz; 0-30 pA), and high at high frequencies and amplitudes (P = 0.8-1; 3.125-31.25 Hz; 30-200 pA). The exact relationship between P and amplitude was difficult to describe because of the well-known low-pass properties of the membrane, which resulted in amplitude attenuation of high-frequency compared with low-frequency command currents. To formalize the analysis we used a leaky integrate and fire (LIF) model with a noise term added. The LIF model was able to reproduce the experimentally observed properties of P as well as the low-pass properties of the membrane. The LIF model enabled us to use the mathematical theory of nonlinear oscillators to analyze the relationship between amplitude, frequency, and P. This was done by systematically calculating the rotational number, N, defined as the number of spikes divided by the number of periods of the command current, for a large number of frequencies and amplitudes. These calculations led to a phase portrait based on the amplitude of the command current versus the frequency-containing areas [Arnold tongues (ATs)] with the same rotational number. The largest ATs in the phase portrait were those where N was a whole integer, and the largest areas in the ATs were seen for middle to high (>3 Hz) frequencies and middle to high amplitudes (50-120 pA). This corresponded to the amplitude- and frequency-evoked increase in P. The model predicted that P would be high when a cell responded with an integer and constant N. This prediction was confirmed by comparing N and P in real experiments. Fitting the result of the LIF model to the experimental data enabled us to estimate the standard deviation of the internal neuronal noise and to use these data to simulate the relationship between N and P in the model. This simulation demonstrated a good correspondence between the theoretical and experimental values. Our data demonstrate that interneurons can respond with a high reliability of spike timing, but only by combining fast and slow oscillations is it possible to obtain a high reliability of firing during rhythmic locomotor movements. Theoretical analysis of the rotation number provided new insights into the mechanism for obtaining reliable spike timing.BM
AN ANALYSIS OF SPEECH ACT IN “ROSI EKSKLUSIF” TALK SHOW
Get PDFThis research aimed to analyze the three types of speech act: locutionary act, illocutionary act and perlocutionary act and the dominant type of illocutionary act found in “Rosi Eksklusif” talk show. The methodology employed in the present research is qualitative, and the data validity uses thick, rich description and member checking. The discourse in the form of talk show analyzed in this study is from “Rosi Eksklusif” talk show with title “[FULL] Blak-blakan Sri Mulyani Klarifikasi “Badai” di Kemenkeu | Rosi Eksklusif” published by KompasTV official Youtube channel in 2nd of March 2023 and the duration of the talk show is 1 hour long. The talk show was analyzed using speech act theory by Yule the for locutionary act and the perlocutionary act and Searle’s theory for the illocutionary act. In the description, the analysis focused on Rosi and Sri Mulyani utterances by investigating the locutionary act, illocutionary act, and perlocutionary act occured in the talk show. This research revealed that (1) there were 96 sentences from the data interview that contained locutionary act, illocutionary act, and perlocutionary act. There were 73 locutionary act, 96 illocutionary act, and 9 perlocutionary act. (2) the dominant illocutionary type is the assertive type
The inspection of retaining walls using GPR
No full textIn hilly regions, retaining walls along roads, motorways and railway lines are numerous. In some cases the knowledge of the details of the construction is limited. If rehabilitation work becomes necessary, a detailed knowledge of the construction is desirable for the improved planning of maintenance and repair. This paper describes the application of Ground Penetrating Radar (GPR) for the inspection of retaining walls. The work was carried out in two steps. First, an investigation was carried out on large retaining walls at a Swiss motorway within the framework of a service contract. This included the development of an apparatus enabling high precision positioning of the antennas on the walls. Second, a pilot study was performed on a smaller wall with optimized acquisition and processing parameters. This included the use of antennas with different orientations and the fusion of the two corresponding datasets as well as true 3-D data processing. This paper describes the approaches to data acquisition and processing in the form of the two case studies. Results from different acquisition and processing strategies are compared and the benefits and limits are discussed.MC