Waste sanitary landfilling is generally opposed by public opinion as responsible of aquifer contamination even when other possible contaminating sources exist in the area. A new tool based on time-spatial evaluation of groundwater contamination is presented, capable of appreciating the direct responsibilities of a MSW sanitary landfill when the aquifer becomes polluted. A successful application of the tool to the case of a medium-size Italian city is discussed.
The effluents from the water treatment station of REGIDESO located in Kingabwa (Kinshasa city) are accused of reducing aquatic biodiversity of Matete and N'djili rivers and are responsible of some human diseases. The effects of these effluents on the physico-chemical and biological quality of water of Matete and N’djili rivers were evaluated. The benthic macro-invertebrates and Gambusia affinis were used as biodiversity richness indicator and model system for toxicity assays. The analyses of physicochemical parameters revealed a constant temperature in the stations studied (± 25 °C) and a high value of conductivity in the sites near the effluents discharge location. On the whole of the sites, the bacterial load was reduced to the neighboring sites of the effluents discharge. The pH is slightly acidic depending on the period and the sampling sites. Dissolved oxygen decreases as sampling seasons. 1405 specimens of benthic macro-invertebrates including 499 in the rainy season and 906 in dry season were harvested. The Shannon index value ranges from 0.4 to 2.9 during rainy season and 1.7 to 2.9 during dry season, reflecting the passage of polluted water to moderately pollute in rain season and moderately polluted to slightly pollute in the dry season. The toxicity bioassay revealed that these effluents are toxic (LC50= 0.109%). It is thus desirable to install a monitoring system near of the station of water purification of the REGIDESO N’djili in order to regularly control the dangerosity of the effluents poured in the surrounding watery ecosystems.
The purpose of this study is to examine the technical efficiency of Ghanaian maize farmers from the parametric perspective. In this study, the stochastic frontier approach (SFA) assumed the Cobb-Douglas functional form and technical efficiency of Ghanaian maize farmers is then estimated using first phase data from the database of sub-Saharan Africa’s intensification of food crops agriculture (Afrint I). Using household characteristics, human capital, farmer’s resource situation, social capital and experience variables, the study found that farmers are producing below the frontier with average technical efficiency of 53 percent. Policy variables such as credit access; education and extension access and farm size played a stronger role in technical efficiency levels.
A floristic inventory of grass and undergrowth was carried out in the southern block of the Yoko Forest Reserve in the Eastern Province. This study aimed to identify grasses and undergrowth, and evaluate the wealth of this areal florula. Transect methods and phytosociological survey was the approach used. A total of 116 plant species have been inventoried and are belonging to 92 genera and 44 families. Note that the dominant families and features are: Commelinaceae (7.76%) and Rubiaceae (6.90%). The relative densities of species and the highest are those of family Marantochloa congensis (174.0 feet/ha) and Marantaceae (360.0 feet/ha). The relative frequencies of the most observed species are those of Palisota barteri (3.21%) and Cola congolana (3.39%), while those of family are Arecaceae, Commelinaceae, Connaraceae, Euphorbiaceae, Lomariopsidaceae, Malvaceae, Marantaceae and Menispermaceae (6.25%). Simpson's diversity index (0.957), Shannon’s diversity index (3.619) and equitability (0.798) revealed that this florula is diversified and its species are well distributed. It is thus desirable that this study is extended to other forest reserves and forest groupings of Kisangani city and its surroundings in order to establish a better database necessary for the sustainable management of the classified forests and other sites of high value for the conservation.
Detailed simulations in aim to evaluate optical performances of a solar parabolic trough collector for various solar tracking modes under climatic conditions of Maroua have been investigated by using the empirical model of Capderou, incidence angle, day of the year, solar direct radiation, legal time, incident angle modifier and global energy absorbed by the heat collection element during the sunniest and the least sunny month. The performances of the three tracking modes assumed compare to full tracking mode during a typical sunny day in Maroua, lead to percentages 98%, 99.98% and 69.25% in the sunniest month and 91.2%, 81.45%, and 62.85% in the least sunny month for East-West polar tracking, East-West horizontal tracking and North-South horizontal tracking respectively. Besides, the results show that, the East-West horizontal and East-West polar solar tracking modes are more suitable and getting closer with full tracking compared the North-South horizontal tracking mode. The optical efficiency reached at about 74% according to the East-West horizontal and East-West polar solar tracking mode and maximum temperatures of 180°C for air and oil and 90°C for water were reached by applying East-West polar and East-West horizontal tracking modes in a typical day of the sunny month.
Detailed simulations in aim to evaluated performances of a solar parabolic trough collector under climatic conditions of Cameroon Sahelian Zones was devoted by using a computer program based on one-dimensional flow implicit finite volume method with energy balance. The heat collecting element of the collector was divided into several control volume and heat balance correlations was applied for each control volume of the trough. In other to solve the three linear algebraic equations obtained from the model, the Tri-Diagonal Matrix Algorithm was implemented. At all, the model estimates for a typical day of the least sunny and the sunniest months, the optical and thermal performances of the collector, the solar energy absorbed the useful thermal heat and the heat lost to the ambient. The E-W horizontal traking mode which is getting closer with full tracking mode is assumed to collect high optical efficiency at about 74% during all the seasons. The maximum of outlet temperature of heat transfer fluid obtained at the right end of the absorber tube is about 140°C, 138°C and 80°C during a typical day of the least sunny months and 180°C, 180°C and 90°C during a typical day of the sunniest month respectively for water, air and TherminolVP-1TM synthetic oil used as heat transfer fluid. Outlet temperatures obtained from the model compared with data from Sandia experimental tested collector and from another devoted work show that the model is very suitable to predict the behavior of a solar parabolic trough collector under climatic conditions of Cameroon Sahelian Zones.
La mastite granulomateuse idiopathique est une maladie inﬂammatoire rare, d’étiologie inconnue. Elle affecte la femme jeune, en période d’activité génitale. C’est une pathologie méconnue qui pose aux cliniciens et radiologues des difficultés diagnostiques, étant donné qu’elle mime souvent une mastite carcinomateuse tant sur le plan clinique que radiologique. Son diagnostic repose sur l’examen anatomopathologique et l’exclusion des autres causes de granulome. Sa pathogénie reste obscure mais le rôle des corynébactéries est discuté. Le traitement est médical associé à l’exérèse chirurgicale. Le pronostic de cette affection reste favorable. Nous rapportant un cas à travers lequel nous discutant les aspects, épidémiologiques, cliniques, diagnostiques, thérapeutiques et évolutifs de cette rare entité.
The beat hunting represents an important source for food and income for populations in the northern Benin. But, although the bush meat is well appreciated by the population, it could also be a source for diseases then the wildlife is a great reserve of several dangerous microorganisms. In that respect the appearance of Ebola and Lassa virus in Benin had affected the consumption of bush meat and thereby the beat hunting. The analysis of this economic activity in the context of the Lassa epidemic was the subject of the present study. Based on a random sample of 150 hunters and using the “Before-and-After” approach, the results showed that the averages of gross margins in the absence and in the presence of the epidemic were 126 314 F and 140 489 F CFA respectively. With a probability of p=0.20, the difference of means is however no significant, suggesting, as also showed by the score of the hunters’ perception on the impact of the epidemic, that the Lassa epidemic had only a limited financial effect on their hunting activity; hoping thereby that their activity again increases as soon as the psychosis generated by Ebola and Lassa virus would disappeared. The indifference of hunters to the risks linked to these epidemics calls however, for the need of deeper future studies on the perception and motivation of hunters for hunting in periods of sanitary crisis in order to prevent public health catastrophes in the study area.
The conductance data of sodium diethyldithiocarbamate (NaDDC) in water solutions at various temperatures (25, 30, 35 and 40°C) are presented. The results were construed by applying the Fuoss-Onsager equation to obtain the parameters: equivalent conductance at infinite dilution (Λo), the distance of closest approach (å) and association constant (KA). In the light of the solvent separated-ion pair model, the KA trend is discussed. A comparison was done between the value of å and the sum of calculated electrostatic Stokes' radii R+ and R-. Both of thermodynamic functions (ΔHo, ΔGo, ΔSo) and the activation energy (ΔEs) were determined; the Λo values were noticed to increase gradually with the dramatic increase in temperature referring to less solvation or higher ions mobility. Negative values of Gibbs free energy change ΔGo for (NaDDC) indicate that the association process is preferable than the dissociation process. The positive value of (ΔHo) points to that the association process is endothermic. Entropy change (ΔSo) values were positive which means that the solvation of ion-pair decreases emulated to that of the free ion.
The traditional machine-tools setting’s consists to rend each characteristic independent, it is for example the case of the transfer of dimension starting to the reference surface which allows taking one adjustment parameter (corrector) by one dimension. The setting in this case is trivial, because there is no dependence between characteristics. The modern machines allow henceforth the simultaneous realization of several operations in one manufacturing phase that put in question the traditional setting. In this context, the relations between manufactured characteristics on the part (or probed points on surfaces) and the correctors are complex, because it exist dependence of setting between surfaces. The Total Inertial Steering (TIS) approach that we present in this article allows to establish a direct relationship between the tool offsets available on the machine and the points of the surfaces through an incidence matrix In most cases, this matrix is not square and therefore not invertible, because there are more probed points as correctors to adjust. The Gauss pseudo-inverse allows to find solution that minimize deviations on the next parts. The problem come up when the same cutting tool machine two surfaces with different point values, the resulting solution favors the one with the highest number of points, at the expense of the other surface which can remain not conform. To remedy this problem, we propose in this article an original method to rebalance setting on surfaces, and this regardless of the number of points.