2,011 research outputs found
Dynamique du Littoral de Vridi-Port-Bouët (Abidjan, Côte d’Ivoire) : Caractérisation Géomorphologique et Sédimentologique
Cette étude porte sur la caractérisation géomorphologique et sédimentologique du secteur littoral de Vridi-Port-Bouët. Pour ce faire, trois campagnes de levés topographiques de profils de plage ont été réalisées à partir d’un niveau de chantier afin de suivre l’évolution morphologique de la zone d’étude. Des sédiments ont été prélevés à différents niveau de l’estran dans le but de déterminer la granulométrie et la morphoscopie des grains de sables. La vitesse du courant de dérive et le volume de sédiments transportés ont été déterminés à partir de la formule de Kaczmarek et al. (2005). D’une façon générale, l’ensemble des profils réalisés montre que certaines zones sont en érosion et d’autres plus ou moins stables. Les profils à proximité du canal et ceux au niveau du phare (C1, C2 et C7) présentent une instabilité du trait de côte et une érosion significative de l’estran. Le secteur de plage au niveau du profil 6 est relativement stable.
La granulométrie des sables varie de très grossiers à grossiers et modérément à bien classé avec une symétrie à l’échantillon ou vers les éléments grossiers
à fins. On constate une diminution de la taille des grains de quartz dans le sens de la dérive. L’examen morphoscopique indique que les grains de quartz évoluent de sub-anguleux non usé à arrondi et émoussé luisant en passant du canal de Vridi au phare de Port-Bouët. La vitesse du courant induit la dérive littorale est évaluée à 0,65 m/s. Cela entraine un transport sédimentaire de 0,02305 m3/s.
This study concerns the geomorphological and sedimentological characterization of the coastal sector of Vridi-Port-Bouët. To do this, three campaigns of topographic surveys of beach profiles were carried out from a site level in order to follow the morphological evolution of the study area. Sediments were collected at different levels of the foreshore in order to determine the grain size and morphoscopy of the grains of sand. The drift current velocity and the volume of sediment transported were determined from the formula of Kaczmarek et al. (2005). In general, all the profiles produced show certain areas in erosion and others more or less stable. The profiles near the canal and those at the lighthouse (C1, C2 and C7) show instability of the coastline and significant erosion of the foreshore. The beach sector at profile 6 is relatively stable.
The granulometry of the sands varies from very coarse to coarse and moderately to well graded with symmetry to the sample or towards coarse to fine elements. A reduction in the size of the quartz grains is observed in the direction of the drift. Morphoscopic examination indicates that the quartz grains evolve from unworn sub-angular to rounded and blunt shiny passing
from the Vridi channel to the Port-Bouët lighthouse. The speed of the current induced the littoral drift is evaluated at 0.65 m/s. This leads to a sediment transport of 0.02305 m3/s
Dynamique du Littoral de Vridi-Port-Bouët (Abidjan, Côte d’Ivoire) : Caractérisation Géomorphologique et Sédimentologique
Cette étude porte sur la caractérisation géomorphologique et sédimentologique du secteur littoral de Vridi-Port-Bouët pour une révision des connaissances acquises en vue d’une meilleure compréhension des réponses morphologiques dans un contexte mondial de changement climatique sur un domaine littoral fortement dynamique. Pour ce faire, trois campagnes bimestrielles de levés topographiques de 7 profils cross shore de plage ont été réalisées à l’aide d’un niveau de chantier. Des sédiments ont été prélevés sur 4 profils à différents niveaux de l’estran (haut, mi et bas estran) dans le but de déterminer la granulométrie et la morphoscopie des grains de sables le long de ce secteur de côte. La vitesse du courant de dérive et le volume de sédiments transportés ont été déterminés à partir de la formule de Kaczmarek et al. (2005). De façon générale, l’ensemble des profils réalisés montre que certaines zones sont en érosion et d’autres plus ou moins stables. En effet, les profils C1, C2 et C7 présentent une instabilité du trait de côte avec une érosion significative de l’estran. Le secteur de plage au niveau du profil C6 est relativement stable.
Les sables sont très grossiers à grossiers et modérément à bien classés. Le skewness indique une symétrie granulométrique de l’échantillon pour les échantillons prélevés sur les sites 1 et 3. Sur le site 2, on a une symétrie vers les éléments fin. Les échantillons du site 4 présentent une asymétrie vers les éléments grossiers. Les grains de quartz évoluent de sub-anguleux non usés à arrondis et émoussés en passant du canal de Vridi au phare de Port-Bouët. On en déduit que la taille des grains diminue dans le sens de la dérive littorale. La vitesse du courant induit par la dérive littorale est évaluée à 0,65 m/s. Cela entraine un transport sédimentaire latéral de 0,02305 m3/s.
This study covers the geomorphological and sedimentological characterization of the coastal area of Vridi-Port-Bouët to revise the knowledge acquired with a view to a better understanding of morphological responses in a global context of climate change in a highly dynamic coastal zone. To this extent, three bimonthly topographic surveys of 7 cross-shore beach profiles were carried out using a construction level. Sediments were collected from 4 profiles at different levels of the foreshore (high, mid, and low foreshore) in order to determine granulometry and morphoscopy of sand grains along this stretch of coastline. The speed of the drift current and the volume of sediment transported were determined using the formula of Kaczmarek et al. (2005). Generally speaking, all the profiles produced show that some areas are eroding when others are more or less stable. Profiles C1, C2, and C7 show an unstable coastline, with significant erosion of the foreshore. The beach area on profile C6 is relatively stable. The sands are very coarse to coarse in size and moderately to well-graded. Skewness indicates particle size symmetry for samples taken at sites 1 and 3. On site 2, there is a symmetry towards fine elements. Samples from site 4 show asymmetry towards coarse elements. Quartz grains move from being sub-angular and unworn to rounded and blunt as they move from the Vridi canal to the Port-Bouët lighthouse. This suggests that grain size decreases in the direction of longshore drift. The current velocity induced is estimated at 0.65 m/s. This results in lateral sediment transport of 0.02305 m3/s
Dynamique du Littoral de Vridi-Port-Bouët (Abidjan, Côte d’Ivoire) : Caractérisation Géomorphologique et Sédimentologique
Cette étude porte sur la caractérisation géomorphologique et sédimentologique du secteur littoral de Vridi-Port-Bouët. Pour ce faire, trois campagnes de levés topographiques de profils de plage ont été réalisées à partir d’un niveau de chantier afin de suivre l’évolution morphologique de la zone d’étude. Des sédiments ont été prélevés à différents niveau de l’estran dans le but de déterminer la granulométrie et la morphoscopie des grains de sables. La vitesse du courant de dérive et le volume de sédiments transportés ont été déterminés à partir de la formule de Kaczmarek et al. (2005). D’une façon générale, l’ensemble des profils réalisés montre que certaines zones sont en érosion et d’autres plus ou moins stables. Les profils à proximité du canal et ceux au niveau du phare (C1, C2 et C7) présentent une instabilité du trait de côte et une érosion significative de l’estran. Le secteur de plage au niveau du profil 6 est relativement stable.
La granulométrie des sables varie de très grossiers à grossiers et modérément à bien classé avec une symétrie à l’échantillon ou vers les éléments grossiers
à fins. On constate une diminution de la taille des grains de quartz dans le sens de la dérive. L’examen morphoscopique indique que les grains de quartz évoluent de sub-anguleux non usé à arrondi et émoussé luisant en passant du canal de Vridi au phare de Port-Bouët. La vitesse du courant induit la dérive littorale est évaluée à 0,65 m/s. Cela entraine un transport sédimentaire de 0,02305 m3/s.
This study concerns the geomorphological and sedimentological characterization of the coastal sector of Vridi-Port-Bouët. To do this, three campaigns of topographic surveys of beach profiles were carried out from a site level in order to follow the morphological evolution of the study area. Sediments were collected at different levels of the foreshore in order to determine the grain size and morphoscopy of the grains of sand. The drift current velocity and the volume of sediment transported were determined from the formula of Kaczmarek et al. (2005). In general, all the profiles produced show certain areas in erosion and others more or less stable. The profiles near the canal and those at the lighthouse (C1, C2 and C7) show instability of the coastline and significant erosion of the foreshore. The beach sector at profile 6 is relatively stable.
The granulometry of the sands varies from very coarse to coarse and moderately to well graded with symmetry to the sample or towards coarse to fine elements. A reduction in the size of the quartz grains is observed in the direction of the drift. Morphoscopic examination indicates that the quartz grains evolve from unworn sub-angular to rounded and blunt shiny passing
from the Vridi channel to the Port-Bouët lighthouse. The speed of the current induced the littoral drift is evaluated at 0.65 m/s. This leads to a sediment transport of 0.02305 m3/s
L’étalement urbain au péril des activités agro-pastorales à Abidjan
L’urbanisation rapide, pose des défis de logement et d’alimentation à la communauté
internationale dans son ensemble et particulièrement aux pays en voie de développement. A
Abidjan en Côte d’Ivoire, le développement de la commune de Yopougon et la croissance
démographique de près de 4 %, entrainent une importante pression sur les terres agricoles
urbaines et périurbaines. La présente étude met en évidence l’influence de cet étalement
urbain sur les activités agro-pastorales à Yopougon. Une démarche cartographique, suivie
d’une démarche socio-anthropologique a été adoptée. Des entretiens avec questionnaires ont
été effectués avec 93 agriculteurs. Cette étude montre que les activités agricoles se
déroulent sur trois principaux sites : Lokoa, Béago et Azito. Entre 2004 et 2007, les sites
agricoles ont connu une réduction d’environ 41 % de leurs superficies du fait de la
croissance urbaine. La variation totale de superficie due aux constructions est de 40Â % Ă
Azito, 18 % à Lokoa et 8 % à Béago. Des parcs à bétails ont changé de position géographique
et se retrouvent en bordure de lagune. L’étude montre également que 94 % des agriculteurs du
site vivent principalement de l’agriculture urbaine et que l’insécurité foncière reste leur
principale préoccupation. L’étalement spatial de la commune de Yopougon, contribue à une
forte réduction des superficies agricoles rendant ainsi vulnérable les familles impliquées
dans les activités agricoles comme principales sources de revenus.Rapid urbanization leads to challenges in housing and food access for all the
international community and particularly in developing countries. In Abidjan, the
developments of Yopougon municipality and population increase have caused significant
pressure on agricultural lands and represent a danger for agriculture in the surrounding
villages. The present study aims at highlighting the influence of urban spread on
agro-pastoral activities in the district of Yopougon. A cartographic approach and a socio
anthropologic approach were used. Observations and individual interviews were made with 93
agricultural actors. Agricultural activities were observed on three principal sites : Lokoa,
BĂ©ago and Azito. Between 2004 and 2007, approximately 41Â % of the agricultural surface was
occupied by settlements. Total variation of surface due to settlements was 40Â % at Azito,
18Â % at Lokoa and 8Â % at BĂ©ago. Some pastoral and cattle parks were joined by the city and
were moved to other geographical positions. For 94Â % of agricultural actors in the studied
site, agriculture was the principal source of income and land insecurity remained the
principal concern of the farmers. The urban sprawl of the municipality of Yopougon
contributes to a strong reduction of agricultural surface. It makes agricultural actors
vulnerable as it is their only source of income
Evaluation de la Pollution Métallique des Sédiments Superficiels de la Lagune Potou en Période d’étiage (Littoral de la Côte d’Ivoire)
La présente étude vise à évaluer la pollution métallique des sédiments superficiels de la lagune Potou (littoral de la Côte d’Ivoire en période d’étiage). La méthode utilisée à cet effet repose en premier sur l’échantillonnage des sédiments et sur la détermination de leurs concentrations en ETM (Élément Trace Métallique) à l’aide de la technique spectrométrique. Ensuite, l’estimation du niveau de la pollution métallique des sédiments, a été faite en comparant les concentrations des métaux obtenues à celles de la croûte continentale de Wedepohl (1995) et à celles des sédiments non pollués de Calamari et Naeve (1994) et Kikouama et al. (2009). De même, l’estimation du niveau de la pollution métallique des sédiments a été réalisée par le calcul de plusieurs indices de pollution dont le facteur d’enrichissement et l’index de géo-accumulation. L’approche méthodologique s’est enfin achevée par l’évaluation des risques des sédiments en place à partir des valeurs guides TEC (Threshold Effects Concentrations) et PEC (Probable Effect Concentration) et par l’étude de la distribution spatiale des différents contaminants au sein de la zone étudiée. Au total, 15 ETM ont été identifiés dans les sédiments du milieu, à savoir l’aluminium (Al), l’arsenic (As), le calcium (Ca), le cadmium (Cd), le chrome (Cr), le cuivre (Cu), le fer (Fe), le potassium (K), le magnésium (Mg), le manganèse (Mn), le sodium (Na), le nickel (Ni), le plomb (Pb), l’antimoine (Sb), et le zinc (Zn). Ces ETM ont des teneurs variables évoluant en moyenne entre 0,81 et 46693,33mg/Kg. Cette importante variabilité est aussi constatée au niveau des valeurs d’enrichissement en ETM. Celles-ci sont comprises en moyenne entre 0,03 et 4,15mg/Kg. Concernant l’index de géo-accumulation, les valeurs trouvées sont en majorité négatives sauf chez le zinc (0,77mg/Kg) et l’antimoine (1,4 mg/Kg). L’ensemble de ces résultats a montré que les sédiments de la lagune Potou sont de mauvaise qualité car pollués par le cuivre, le fer, le zinc et l’antimoine. Ces métaux, en particulier le zinc et l’antimoine, peuvent exercer un effet néfaste sur les organismes aquatiques du milieu lagunaire ainsi que sur l’Homme.
This paper focuses on evaluating the metallic pollution of the superficial sediments of the Potou lagoon (Coast of CĂ´te d'Ivoire) during the low water period. The method used for this study is based, first of all, on the sampling of the sediments and on the determination of their respective concentrations in MTE (Metal Trace Element) using the spectrometric technique. The estimation of the level of metallic pollution of the sediments was made by comparing the concentrations of the metals obtained with those of the continental Wedepohl crust (1995) and those of the unpolluted sediments of Calamari and Naeve (1994) and Kikouama et al. (2009). It was also achieved by calculating several pollution indices including the enrichment factor and the geo-accumulation index. The methodological approach was finally completed by assessing the risks of sediments in place from the TEC (Threshold Effects Concentrations) and PEC (Probable Effect Concentration) guide values and by studying the spatial distribution of the various contaminants at the site within the study area. A total of 15 MTE were identified in the sediments of the medium, namely: aluminium (Al), arsenic (As), calcium (Ca), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), potassium (K), magnesium (Mg), manganese (Mn), sodium (Na), nickel (Ni), lead (Pb), antimony (Sb), and zinc (Zn). These MTE have variable contents ranging on average between 0.81 and 46693.33 mg / kg. This important variability is also found in the MTE enrichment values. These are on average between 0.03 and 4.15. Regarding the geo-accumulation index, the values found are mostly negative except for zinc (0.77) and antimony (1.4). All of these results showed that the sediments of the Potou lagoon are of poor quality because they are polluted by copper, iron, zinc, and antimony. These metals, in particular zinc and antimony, can have a detrimental effect on the aquatic organisms that inhabit the environment as well as humans
Efficacity of ternidazole-neomycin sulfate-nystatin and prednisolone association in syndromic management of vaginitis in low and middle incomes countries
Background: Vaginitis is a frequent and treated based on clinical evaluation in our countries in absence of microbiological laboratories. Evaluate the effectiveness of the management of vaginitis by ternidazole, neomycin sulfate, nystatin, prednisolone association.Methods: A five-month prospective study was carried out in three health facilities in Abidjan. Two-hundred and thirty-three patients with clinical signs of vaginitis were included after signed consent. Pregnant and breast-feeding patients, hypersensitivity or idiosyncrasy to ternidazole, neomycin sulfate, nystatin, prednisolone association were not included. Patients were divided into reference group (n=200) for which a microbiological analysis of vaginal secretions was carried out 2-4 days before treatment and control group (n=33) for which treatment was initiated straightaway. Evaluation criteria were clinical symptoms, microbiological balance carried out 10 to 14 days after treatment and occurrence of side effects. Statistical tests used were Khi2 and exact Fisher test (p<0.05).Results: Pathological leucorrhoea was differently observed in both group (p=0.001). During the follow-up visit, the persistence of symptoms was not different (p=0.99). This combination has demonstrated its efficacy in cases of Candida albicans vaginitis, bacterial vaginosis, trichomonas vaginalis vaginitis, and mixed vaginitis. A significantly improvement of symptoms (p=0.001) and low rate of biologically proven recurrence was observed in both groups. No allergic reactions linked was reported.Conclusions: In our countries this therapeutic combination appears to be an option for treated mixed vaginitis in first intention without preliminary samples of vaginal secretions
Breast location of tuberculosis: a case report and literature review
Breast tuberculosis (TB) is a rare localization of extra-pulmonary TB. We report the first case observed in our daily activities to show the difficulties in the diagnosis and the good evolution in the treatment. In spite of the fact that it is rare, breast TB should not be ignored, especially in a country with high TB endemicity
Land-atmosphere feedbacks exacerbate concurrent soil drought and atmospheric aridity.
Compound extremes such as cooccurring soil drought (low soil moisture) and atmospheric aridity (high vapor pressure deficit) can be disastrous for natural and societal systems. Soil drought and atmospheric aridity are 2 main physiological stressors driving widespread vegetation mortality and reduced terrestrial carbon uptake. Here, we empirically demonstrate that strong negative coupling between soil moisture and vapor pressure deficit occurs globally, indicating high probability of cooccurring soil drought and atmospheric aridity. Using the Global Land Atmosphere Coupling Experiment (GLACE)-CMIP5 experiment, we further show that concurrent soil drought and atmospheric aridity are greatly exacerbated by land-atmosphere feedbacks. The feedback of soil drought on the atmosphere is largely responsible for enabling atmospheric aridity extremes. In addition, the soil moisture-precipitation feedback acts to amplify precipitation and soil moisture deficits in most regions. CMIP5 models further show that the frequency of concurrent soil drought and atmospheric aridity enhanced by land-atmosphere feedbacks is projected to increase in the 21st century. Importantly, land-atmosphere feedbacks will greatly increase the intensity of both soil drought and atmospheric aridity beyond that expected from changes in mean climate alone
Transcriptome sequencing and development of an expression microarray platform for the domestic ferret
<p>Abstract</p> <p>Background</p> <p>The ferret (<it>Mustela putorius furo</it>) represents an attractive animal model for the study of respiratory diseases, including influenza. Despite its importance for biomedical research, the number of reagents for molecular and immunological analysis is restricted. We present here a parallel sequencing effort to produce an extensive EST (expressed sequence tags) dataset derived from a normalized ferret cDNA library made from mRNA from ferret blood, liver, lung, spleen and brain.</p> <p>Results</p> <p>We produced more than 500000 sequence reads that were assembled into 16000 partial ferret genes. These genes were combined with the available ferret sequences in the GenBank to develop a ferret specific microarray platform. Using this array, we detected tissue specific expression patterns which were confirmed by quantitative real time PCR assays. We also present a set of 41 ferret genes with even transcription profiles across the tested tissues, indicating their usefulness as housekeeping genes.</p> <p>Conclusion</p> <p>The tools developed in this study allow for functional genomic analysis and make further development of reagents for the ferret model possible.</p
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The home language environment in rural China: variations across family characteristics
Background
A rich language environment is an important element of a nurturing home environment. Despite their proven importance, vocabulary and conversation have been shown to vary widely across households—even within the same socio-economic class. One significant gap in the existing literature is its nearly exclusive geographic focus on Western and developed settings, with little attention given to poorer communities in lower/middle income countries. The purpose of this study was to empirically illustrate the characteristics of the home language environment in the low SES, non-Western cultural setting of rural China.
Methods
Using Language Environment Analysis (LENA) automated language-analysis system, this study measured the home language environment of 38 children aged 20-27 months in Northwest rural China. Our primary measures of the home language environment were Adult Word Count (AWC), Conversational Turn Count (CTC) and Child Vocalization Count (CVC). Multivariate linear regression models were used to examine the association between home language environment and family/child characteristics, and language skills (Measured by MacArthur-Bates Communicative Developmental Inventory score).
Results
In this paper, by comparison, we found that the home language environment of our rural sample fell far behind that of urban households. We also identify significant, positive correlations between language skills and both AWC and CTC. Our analysis finds no significant correlations between home language environment and family/child characteristics.
Conclusion
In this paper, we present the first ever findings using the LENA system to measure the home language environment of young children from poor rural communities in China. We found that the home language environment of lower-SES household was significantly worse than high-SES households, and demonstrated the importance of the home language environment to language skills, pointing to a need for more high-quality studies of the home language environment in rural China to better understand possible mechanisms behind low levels of parent-child language engagement and ways to improve the home language environment
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