Qui Sont les Femmes en Union Sans Intention d’Utilisation de la Contraception Moderne au Burundi ? Etude du Profil Socio-Démographique à Partir des Données de 2010 et 2016-2017

Dans un contexte qui réclame la maîtrise de la fécondité pour atteindre les objectifs nationaux et mondiaux du développement, la prévalence contraceptive au Burundi reste faible. De surcroît, la proportion des femmes en union sans intention de recourir à la contraception moderne a récemment augmenté. Cette proportion est passée de 53% en 2010 à 66% en 2016-2017. En se basant sur les données des Enquêtes Démographiques et de Santé du Burundi (EDSB) réalisées en 2010 et 2016-2017, cette étude a pour objectif de déterminer le profil socio-démographique des femmes sans intention de contraception moderne. Pour atteindre cet objectif, une Analyse Factorielle des Correspondances Multiples (AFCM) a été utilisée. Les résultats de l’étude montrent que l’âge avancé de la femme et de son conjoint, la parité atteinte élevée et le nombre élevé d’enfants survivants sont les principales caractéristiques de ces femmes. Ces résultats révèlent un problème culturel de fond car ces générations avancées sont sans niveau d’instruction et ne sont ni exposées aux médias ni ouvertes à la modernité. Les interventions futures pour la planification familiale réussie viseraient le changement de vision face à la contraception, tout en encourageant la scolarisation des filles.   In a context that calls for fertility control to achieve national and global development goals, contraceptive prevalence in Burundi remains low. Moreover, the proportion of women in the union without the intention to use modern contraception has recently increased. This proportion increased from 53% in 2010 to 66% in 2016-2017. Based on data from the Demographic and Health Surveys of Burundi (DHSB) conducted in 2010 and 2016-2017, this study aims to determine the socio-demographic profile of women without the intention to use the modern contraceptive. To achieve this objective, a Multiple Correspondence Factorial Analysis (MCA) was used. The results of the study show that the advanced age of the woman and her partner, the high number of children ever born and the high number of surviving children are the main characteristics of these women. These results reveal a fundamental cultural problem as these advanced generations are uneducated and are neither exposed to the media nor open to modernity. Future interventions for successful family planning would aim at changing the vision towards contraception while encouraging girls' schooling

Les poissons du bassin de la rivière Ulindi, à l’Est de la République Démocratique du Congo : revue de la littérature

Cette revue de la littérature sur les poissons du bassin hydrographique de la rivière Ulindi à l’Est de la République Démocratique du Congo a été réalisée dans le but d’avoir une idée sur l’état des connaissances actuelles de son ichtyofaune en vue de définir les orientations pour leurs études ultérieures dans cette région non encore prospectée en profondeur et dont la plupart des rivières se trouvent actuellement menacées par des activités anthropiques. Cette étude présente une vue globale des rivières du Bassin de la rivière Ulindi avec une liste systématique non exhaustive d’environ 31 espèces de poissons appartenant à 17 genres, 9 Familles et 4 ordres, basée sur la méta-analyse des différentes études taxonomiques de l’ichtyofaune du Bassin de la Rivière Ulindi, réalisées depuis l’époque coloniale du Congo-Belge jusqu’en 2019. Les résultats de cette étude constituent une aide-mémoire pour les services publics en charge de la gestion de l’environnement dans la gestion de la biodiversité ichtyologique de cet écosystème à intérêt socio-économique considérable dans la région, d’une part et une liste de contrôle aux scientifiques pour des études ultérieures.Mots clés : Ichtyofaune, Ulindi, République Démocratique du Congo, revue de la littérature, liste de contrôle.   English Title: Fishes from the Ulindi river basin, East of the Democratic Republic of Congo: review of the literatureThis review of the literature on fish in the Ulindi river basin in the east of the Democratic Republic of Congo was carried out with the aim of gaining an idea of the state of current knowledge of its fish fauna in order to define guidelines for their further studies in this region not yet explored in depth and most of the rivers of which are currently threatened by anthropogenic activities. This study presents a global view of the rivers of the Ulindi river basin with a non-exhaustive systematic list of approximately 31 fish species belonging to 17 genera, 9 Families and 4 orders, based on the meta-analysis of the various taxonomic studies of the ichtyofauna of the Ulindi river basin, carried out since the colonial times of the Belgian Congo until 2019. The results of this study constitute a baseline for the public services in charge of environmental management in the management of the ichthyological biodiversity of this ecosystem with considerable socio-economic interest in the region, on the one hand and a checklist to scientists for further studies.Keywords: Ichtyofauna, Ulindi, Democratic Republic of Congo, literature review, checklist. &nbsp

Upgrading of land resources datasets to support rural land use planning in Burundi

Summary With only 25 650 km2 land area but 11.1 millions of inhabitants (2016) the republic of Burundi in central-east Africa is facing a serious food insecurity issue, the more since 90% of the population rely on subsistence agriculture with only 0.14 ha of crop land available per capita. In this context of land scarcity and fragmentation, exacerbated by environmental change, there is an urgent need for better management of the rural land resources and better planning of their use. Assessment models of land performance and planning and decision support systems (P/DSS) are promising tools to address these needs. However, these tools require quantitative and accurate, spatially contiguous coverages of land characteristics data, the major ones being related to topography, soil, climate and land use, which mostly are not readily available. Therefore, the general objective of this research project was to test and further develop approaches to upgrade the existing topography, climate and soil resources datasets for Burundi with a view to feed land performance models and P/DSS. This general objective was pursued through research focusing the following four specific objectives. They were elaborated in the four chapters that follow the introductory chapter of the manuscript: Developing a method to derive a sufficiently accurate digital elevation model (DEM) from available contour lines (published); Comparing SCORPAN (Soil (S) as a function of Climate (C), Organisms (O), Relief (R), Parent material (P), Age (A) and geographic position (N))-based digital soil mapping approaches to estimate top soil clay and organic carbon content (published); Elaborating a method to estimate soil organic carbon stock and soil erodibility from upgraded soil datasets; Modeling potential soil erosion from station-based and gridded climate data and upgraded topographical and soil datasets. The challenging problem of deriving reliable topographic models from contours was tackled in chapter 2. Until recently contours from printed topographic maps were the major source of information on elevation in many countries. To be reliable, a contour-derived DEM should infer the true terrain shape from the pattern of contours. We combined two modelling techniques to obtain such DEM: one based on Triangular Irregular Networks (TIN), and another one belonging to gridding methods that can extrapolate beyond the range of contours. This combination proved successful as it allowed extrapolation to local minima and maxima of elevation –which were not explicitly documented on the contour maps –while avoiding artificial terraces which are common artefacts in contour-derived DEMs. In chapter 3 the inadequacy of conventional and general-purpose categorical soil maps to deliver specific, quantitative and spatially continuous soil information was discussed and alternative digital soil mapping (DSM) techniques having the potential to overcome this inadequacy were tested. Among these DSM we considered several Soil Spatial Prediction Functions with spatially auto-correlated errors (SSPFe) and more specifically the so-called SCORPAN-SSPFe models since apart from accounting for possible spatial auto-correlation among model residuals they supplement Jenny’s soil (S) forming factors (climate (C), organisms (O), relief (R), parent material (P), time or age (A)) with geographical position (N). These DSM-techniques are attractive in that they allow incorporation of any kind of available knowledge in the form of trend components, while accounting for spatial auto-correlation of residuals from the trend components using kriging, further termed residual kriging (RK). The prediction performance of the 1:50 000 soil map of Burundi for topsoil clay and organic carbon content was tested in two ways. First the soil map was considered as a trend model by geo-matching point observations to the soil-map units (SMUs) and next it was a source of categorical covariates in other trend models. The performance of the soil map as a trend model was compared to the one of a litho-topo-map consisting of litho-topo-units (LTUs), i.e. mapping units obtained by combining lithology with DEM-derived landform types. Other alternative trend models tested were: (1) ordinary least squares Linear Regression (LR), (2) Geographically Weighted Regression (GWR), (3) Generalized Additive Models (GAM), (4) Boosted Regression Trees (BRT) and (5) Artificial Neural Networks (ANN). Covariates tested for these trend models were components of the 1:50 000 soil map of Burundi, of the 1:100 000 geologic map of Burundi and of a lithologic map compiled during the soil sampling phase for this project, the Normalized Difference vegetation Index (NDVI) computed from Landsat ETM+ imagery and derivatives of the 20-m contour-derived DEM. The results of geo-matching to SMUs and LTUs indicated that by using only lithology and a DEM one can define land units that predict SOC and clay content better than by using the SMUs on the semi-detailed soil map of Burundi. The best performing trend model was the Boosted Regression Trees for clay content and the Generalized Additive Model for SOC content. For all tested SCORPAN-trend models, incorporating lithology among the explanatory variables resulted in better performance than when soil map components were accounted for. For the case of clay content in which spatial auto-correlation of trend-model residuals was significant, RK augmented the prediction performance beyond the best performing trend models, suggesting that spatial auto-correlation of residuals must not be neglected when using prediction models. The fourth chapter evolved from the third one by testing DSM for estimating and up-scaling SOC stock and soil erodibility (K) from the scarce and multi-source datasets available for northern Burundi. Besides SOC content, SOC-stock estimation required soil bulk density (SBD) for which measurements were not available and also soil rock fragment contents which were available either as mass-basis estimates or volume-basis estimates. Likewise, as K-factor measurements were not available, a K-transfer function that accommodates the available datasets was to be selected from several K-transfer functions proposed in literature, of which the most reliable ones require particle size distribution (PSD) or both SOC and PSD as minimum input. Eventually the so-called K(Dg) model requiring PSD only was selected since co-located PSD and recent SOC measurements were missing. Of the up-scaling techniques that were evaluated in chapter 3, geo-matching and BRT were selected and compared as they both can accommodate missing covariate values. BRT proved to be a better option for up-scaling than multi-level geo-matching. Both up-scaling techniques resulted in spatially auto-correlated residuals, suggesting that SOC and SOC-stock predictions could be further improved by residual kriging. As the estimation of soil erodibility by the K(Dg) model is known to be sub-optimal for some sub-ranges of Dg and SOC, we proposed using the up-scaled SOC map to correct K(Dg). In chapter 5 the valorisation potential of upgraded land resource datasets was demonstrated through the modelling of the potential soil erosion according to the Revised Universal Soil Loss Equation (RUSLE). Coverages of the runoff-rainfall erosivity factor and the topographic factor were estimated and combined with the coverage of the already (in chapter 4) estimated soil erodibility factor to finally propose a new potential soil erosion map for northern Burundi. Coverages of current rainfall and erosivity (2011-2013) were derived from gridded PERSIANN data (≈ 27-km resolution) as too many gaps were found in the available time series of rain gauge stations. Coverages of future rainfall and erosivity (2046 – 2050) were derived from CORDEX rainfall projections (≈ 50-km resolution). Accounting for geomorphology in the bias correction of PERSIANN and CORDEX rainfall data and in the subsequent erosivity estimation resulted in more realistic spatial distributions of rainfall and erosivity in northern Burundi. Comparison of the present with the future CORDEX mean annual precipitations suggested a decrease in mean annual rainfall in Highlands and an increase in the Central plateaus and Northern depressions. The difficulty to adjust the DEM-derived topographic factors in the absence of data on parcel boundaries was found to be the major limitation for reliable estimation of potential soil erosion. It is anticipated that by complementing the potential soil erosion map with coverages of land use and land management (LULM) at parcel resolution it will be possible to end up with maps of the actual soil loss through sheet and rill erosion. Unfortunately such LULM-coverages are not readily available. Finally steps forward to address the limitations and missing information identified in this PhD research were proposed.nrpages: 157status: publishe

Ultrasonic atomization of liquids: Stability analysis of the viscous liquid film free surface

One of the fundamental steps in the process of liquid fan ultrasonic atomization is the hydrodynamic instability. The resulting surface,waves become unstable and tear. This causes a mist of uniform droplets to be formed and ejected. The study of ideal liquid film free surface behavior in the steps prior to droplet formation leads to a stability analysis based on the Mathieu-Hill equation. Unfortunately, a similar analysis cannot realistically be developed for a viscous liquid. The present work performs a linear analysis derived from the hydrodynamics, which allows a stability analysis of viscous bounded liquid film free surface. Actual results are compared to those obtained in the case of an inviscid fluid

Characterization of Sprays Produced by Low Frequency Ultrasonic Atomizers

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Characterization of Sprays Produced by Low Frequency Ultrasonic Atomizers

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Experimental and theoretical study of sprays produced by ultrasonic atomisers

The atomisation of liquids by means of low-frequency ultrasonic atomisers results from unstable surface waves generated on the free surface of a thin liquid film. These unstable waves are obtained from the tuning of the amplitude and the frequency of an imposed oscillation. The thin liquid film develops as the liquid spreads over the atomising surface of the atomiser. This paper focuses on a systematic experimental analysis of the sprays produced by low-frequency ultrasonic atomisers. The thickness of the liquid film was measured and its effects on the drop diameter were studied to ether with the effects of both the liquid's physical properties and the ultrasonic atomiser's characteristics. The relationship between the mean drop diameter and the surface wave wavelength was accurately determined and introduced into a mathematical approach based on the maximum entropy formalism to predict the drop size distribution of the spray. Within the range nf working conditions tested the application of this formalism is successful and provides a procedure for the prediction of spray drop size distributions from calculations only

Des services publics forts pour bâtir la résilience

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