Révéler ce qui fait communauté dans un système irrigué par l'analyse des dynamiques conflictuelles

Les systèmes d'irrigation communautaires sont souvent mis en avant pour leur mise en pratique des principes de participation et de gestion des communs. Ces systèmes sont aussi des arènes d'antagonismes et de conflits, et des objets de convoitise et d'interventions extérieures, qui redéfinissent l'espace, l'organisation sociale et les modes de partage de l'eau. Nous avons étudié un système irrigué dans la province d'El Hajeb où l'on observe des dynamiques conflictuelles inscrites dans une temporalité longue et dans des jeux d'acteurs complexes. L'analyse de quatre dynamiques conflictuelles, nous a permis d'identifier les moments et les espaces d'émergence et de repli de la communauté. La matérialisation de ces dynamiques se traduit par une appropriation ou une nouvelle création des ressources en eau, une réadaptation de l'infrastructure d'irrigation ou encore par la mobilisation opportuniste des règles de partage et de distribution de l'eau. A travers ces dynamiques conflictuelles, la communauté se donne à voir dans toute sa complexité et ses contradictions. Cette communauté présente un construit social non immuable et change selon les intérêts en vigueur et la référence mobilisée: sociale, territoriale, culturelle ou historique. La multitude de références et la mobilisation à géométrie variable des groupes dans les situations conflictuelles illustrent les recompositions sociales fortes vécues par la communauté d'irrigants. Elles montrent la fragilisation de l'enracinement de cette communauté suite aux interventions externes depuis le protectorat. (Résumé d'auteur

Paralysie du nerf abducens droit révélant une pansinusite

L'association entre la sinusite, en particulier, sphénoïdale et la paralysie oculomotrice a été déjà décrite dans la littérature, mais reste très rare. Nous rapportons un cas d'une patiente âgée de 14 ans sans antécédents pathologiques particuliers consultant pour une une paralysie du VI gauche survenant dans un contexte fébrile. L'examen ophtalmologiquet complété par un bilan radiologique, à révélé une pansunisite du même coté. Les auteures suggèrent que devant toute paralysie oculomotrice, et après avoir éliminé une étiologie tumorale, il faut rechercher à un foyer infectieux locorégional et le bien traite

The behavior of the concretes and mortars reinforced by metallic fibers wastes as substitution of cement

Abstract The main objective of this work is to study the behavior of the mortar and the concretes obtained by substituting the cement by the metallic fibers wastes. Several materials were carried out by substituting the cement with different amount of fibers (0, 10, 20 and 30 wt %). Mechanical properties of the two obtained materials (mortar and concrete) as flexural and compressive strengths were studied. Physical properties as shrinkage, the swelling effect, loss in mass, slump concretes and porosity were evaluated. However, the addition of 10 wt % of the fibers in the mixtures of the mortar and the concretes is possible, due that its compressive strengths are respectively 40.9 and 27.4 MPa. The environmental risks of the incorporation of the metallic fibers rich in heavy metals (Zn and Cu) into the mixtures were evaluated by leaching tests of the obtained materials. The results indicated a very slight release of the pollutants. The obtained materials have a good performance and they are suitable for use in practice

Biosorption of Co (II) ions from aqueous solutions using selected local Luffa Cylindrica: Adsorption and characterization studies

The present study is concerned with the removal of Cobalt (II) from aqueous solution by adsorption onto low cost adsorbent. Luffa Cylindrica as adsorbent, (LC) was investigated in batch adsorption system. LC was characterized by Scanning Electron Microscopy (SEM) and Brunauer-Emmett-Teller (BET) surface area analyzer. The sorption of Co (II) ions by LC was subjected to equilibrium, thermodynamics and kinetic studies and was carried out by considering the effects of pH, effect of masse and particles size of the biosorbent, initial metal ions concentration, contact time and temperature. BET surface area of LC was 46.396 m2/g. The optimum conditions for maximum adsorption were attained at pH 6 and LC mass is 1.5 g with particle size is < 0.08 mm and contact time is 60 min. The pseudo-second-order rate equation described the Kinetic data well. The process is chemisorptive and controlled by the pseudo-second-order. Adsorption parameters were determined using both Langmuir and Freundlich isotherms, but the experimental data were better fitted to the Langmuir equation than to Freundlich equation, with correlation coefficients above 0.99 which indicates the adsorption is monolayer adsorption with maximum adsorption capacity for Co(II) was 2.53 mg/g

Application de certains indices diatomiques à un cours d'eau marocain : Oued Hassar

Les eaux de l'Oued Hassar (Maroc) sont caractérisées par une forte minéralisation. La conductivité, variant entre 3470 et 7210 µS.cm-1, est due essentiellement aux fortes teneurs en chlorures. L'examen de l'Indice de Pollution Organique (IPO) montre que l'effluent d'eaux usées provenant de la ville de Mediouna constitue la principale source de pollution des eaux de l'Oued Hassar.Concernant l'étude des diatomées épilithiques, 61 espèces et variétés de diatomées ont été inventoriées. Ces taxons sont liés particulièrement à la salinité (Pleurosira laevis, Fragilaria pulchella,…) et à la charge organique (Nitzschia palea, Gomphonema parvulum,…).Quatre indices diatomiques ont été testés pour l'évaluation de la qualité des eaux de l'Oued Hassar : l'Indice Diatomique Pratique (IDP), l'Indice Diatomique Générique (IDG), l'Indice de Sládecek (SLA) et l'Indice Diatomique Trophique (IDT). La variation spatio-temporelle de ces indices reflète bien la dégradation de la qualité de ce cours d'eau, particulièrement en aval du rejet de la ville de Mediouna (IDP=3,86 ± 1,84 ; IDG=6,05 ± 1,95 ; SLA=4,35 ± 1,93 ; IDT=5,80 ± 1,31). Parmi ces indices testés, seul l'IDP présente une corrélation significative (0,63 ; α<5%) avec l'IPO (indice de référence) tandis que l'IDG, le SLA et l'IDT montrent des corrélations non significatives avec cet indice (0,38 ; 0,27 et -0,11 respectivement).The water quality in Moroccan rivers and streams becomes more and more injured because of the important amount of pollutants discharged in these aquatic ecosystems without any treatment in the most cases. A physical, chemical and microbiological analyses are regularly done by public institutions (office national des eaux potables, direction de l'hydrolique). However, these analyses become insufficient facing the big diversity of chemicals and the intermittence of pollution sources at the time. So, methods using a biotic indicators as a complement of the chemical analyses become a requirement in the water quality assessment. In the present study, besides the physical and chemical analyses, we have tested the use of benthic diatoms as indicators of the oued Hassar water quality and diatom indices as a tool for the evaluation of this quality.Oued Hassar is a canalized stream situated on the valley of oued Mellah river. It drains a part of the Berrechid groundwater as sources. Its main source (station SC) is situated to 3 km in the Northeast of Mediouna (155 m). Along this water course, in sections of various degrees of water pollution, six sites (SC, SB, HP, OM, SH and CA) were sampled on four different dates (august 1997 and january, june and august 1998). The station OM belongs to oued Mouileh stream which is a unique tributary of oued Hassar. The main source of pollution; the wastewater effluent of Médiouna agglomeration entered the stream between The oued Hassar source and the station SB (Sidi Brahim). This region has a Mediterranean semi-aride bioclimate. The influence of the ocean results in a summer temperatures generally varying between 25 and 30°C and winter temperatures varying between 12 and 19°C.The physical and chemical analysis data of the oued Hassar waters show particularly elevated values of water conductivity essentially due to the high contents in chlorides. These values were understood between a minimal value recorded at station SH in August 1998 (3470 mS.cm-1) and a maximal value signalled at station OM in January of the same year (7210 mS.cm-1). Concentrations in sulphates vary according to stations. The most elevated values were recorded in january 1998 at stations SC and OM (231 and 218 mg.l-1 respectively). The hardness values are very important especially at the source of oued Hassar (SC) where the concentration reaches 25,2 meq.l-1. This excessive mineralization of waters, particularly at stations SC and OM, is essentially due to the Permo-triasique saliferous sedimentary layers which crop out in the area.The oued Hassar stream receives, to 100 ms downstream the station SC, the wastewater effluent of Médiouna agglomeration, highly loaded with organic matters, ammonia, orthophosphates and suspended matters. The impact of this effluent results on the elevated values of these parameters downstream the wastewater input (SB). On January 1998 (rainy period), the important contents in orthophosphates and sulphates recorded at all stations were essentially due to the high amounts of superphosphates and ammonia sulphates used as amendment of the cultivated lands situated a long the sides of oued Hassar stream.Outside of this period, contents in orthophosphates and ammonia at stations SC and OM are very low. However, the elevated content in nitrates at the oued Hassar's source (maximal value: 93,3 mg.l-1) gives an idea on the deterioration of the groundwater quality.To put in evidence the evolution of the global organic pollution of waters, the "Indice de Pollution Organique" (IPO) have been calculated. The exam of this index shows that the wastewater effluent constitutes the main source of pollution. Indeed, water quality goes from a mean pollution state (3,88 ± 0,14) at the oued Hassar's source to a very strong pollution state (1,96 ± 0,31) at the station SB. Downstream the swampy zone, at the station HP, the water quality of oued Hassar improves remarkably (3,50 ± 0,74) due to the auto-purification phenomenon and the dilution of these waters by those coming from the secondary sources situated between stations SB and HP. At the stations SH and CA, the IPO mean values (3,50 ± 0,79 and 3,75 ± 0,41 respectively) show that the water quality remains rather identical as at the station HP.Concerning the survey of epilithic diatoms, 61 species and varieties of diatoms have been inventoried. These taxa are bound especially to the salinity (Amphora coffeaeformis, Fragilaria fasciculata, Fragilaria pulchella, Pleurosira laevis,…) and to the organic load (Gomphonema parvulum, Navicula subminuscula, Nitzschia palea,…). In the most collected samples, particularly at the stations SB, SH and CA, diatom communities are essentially dominated by N. palea and the complex N. inconspicua / N. frustulum. At the station SB, the relative abundance of N. palea reaches 71% in august 1997 and august 1998, and goes beyond 45% in January and june 1998. giving evidence of the important organic pollution. this species is substituted, at stations SH and CA, essentially by Navicula subminuscula, N. veneta and Nitzschia inconspicua / N. frustulum complex. Diatom communities at the stations SC, HP and OM don't show an exclusive dominance of one or two species, but several species dominate and form a more varied communities.Four diatom indices have been tested to assess the water quality in Oued Hassar (Morocco) : the "Indice Diatomique Pratique" (IDP), the "Indice Diatomique Générique" (IDG), the Sládecek Index (SLA) and the Trophic Diatom Index (TDI). These indices are different by the assigned indicative values and pollution sensitivity coefficients relative to every species and by the taxonomic list integrated in the calculation of every index. The spatio-temporal variation of these indices reflects clearly the deterioration of water quality downstream the wastewater input of Mediouna agglomeration (IDP=3,86 ± 2,30; IDG=6,05 ± 2,31; SLA=4,35 ± 2,62; IDT=5,80 ± 1,85) and its recovery after the swampy zone at the station HP (IDP=9,37 ± 2,35; IDG=11,83 ± 1,77 ; SLA=7,19 ± 3,05 ; IDT=6,76 ± 2,48). Among these indices, only the IDP presents a significant correlation (0,63 ; α<5%) with the IPO (reference index). While the IDG, the SLA and the TDI don't show a significant correlation with this index (0,38 ; 0,27 and -0,11 respectively). The IDT shows nearly the same water quality in the different stations and rather inform on the high level of eutrophication in these water courses.The physical and chemical analyses, the composition of diatom communities as well as the relative results of diatom indices, show that the oued Hassar stream is submitted to an important pollution, particularly downstream the wastewater input. Among the tested indices, the IDP appears more adapted to the assessment of water quality in oued Hassar. However, more work is required in order to finalize a new diatom index which is more adapted to characteristics of the Moroccan water courses

Reactivity of 3-hydroxy-3-methyl-2-butanone: Photolysis and \OH\ reaction kinetics

International audienceHydroxycarbonyl compounds are important secondary reaction products in the oxidation of Volatile Organic Compounds (VOCs) in the atmosphere. The atmospheric fate of these oxygenated \VOCs\ is however poorly understood, especially the relevance of the photolytic pathway. In this work, a combined investigation of the photolysis and temperature-dependent \OH\ radical reaction of 3-hydroxy-3-methyl-2-butanone (3H3M2B) is presented. A photolysis lifetime of about 4-5 days was estimated with a global quantum yield of 0.10. The \OH\ reaction rate coefficient follows the Arrhenius trend (298-356 K) and could be modelled through the following expression: k3H3M2B(T) = (5.12 ± 0.07) × 10−12 exp(−563 ± 119/T) in cm3 molecule−1 s−1. A 3H3M2B atmospheric lifetime of 15 days towards the \OH\ radical was evaluated. Our results showed that the photolysis pathway is the major degradation channel for 3H3M2B. Photolysis products were identified and quantified in the present work with a carbon balance of around 80% enabling a reaction mechanism to be proposed. The present work underlines the need for further studies on the atmospheric chemistry of oxygenated VOCs

Révéler ce qui fait communauté dans un système irrigué par l'analyse des dynamiques conflictuelles

Community irrigation systems are often acclaimed for putting in practice the principles of participation and management of the commons. However, these systems are also arenas characterized by internal antagonisms and external intervention, which generate a redefinition of space, social organization and of water sharing. We studied an irrigation system in the province of El Hajeb where long-standing conflicting dynamics can be observed. The analysis of four conflicting dynamics, involving different social groups, allowed us to identify the moments and spaces of emergence and decline of the community. These conflict dynamics resulted in the appropriation and new creation of water resources, rehabilitation of irrigation infrastructure or by opportunistic mobilization of the community rules for sharing water. Through these dynamics, the community can be seen in all its complexity and contradictions. The irrigators’ community is a social construct that is not immutable. It changes depending on the individual and collective interests and mobilized references: social, territorial, cultural or historical. The multitude of references and their use by different groups in conflict situations illustrate the strong social restructuring experienced by the community of irrigators. This shows the fragility of the roots of this community due to external interventions since the protectorate. Keywords: Conflict dynamics, community of irrigators, Bittit, Morocco.Les systèmes d’irrigation communautaires sont souvent mis en avant pour leur mise en pratique des principes de participation et de gestion des communs. Ces systèmes sont aussi des arènes d’antagonismes et de conflits, et des objets de convoitise et d’interventions extérieures, qui redéfinissent l’espace, l’organisation sociale et les modes de partage de l’eau. Nous avons étudié un système irrigué dans la province d’El Hajeb où l’on observe des dynamiques conflictuelles inscrites dans une temporalité longue et dans des jeux d’acteurs complexes. L’analyse de quatre dynamiques conflictuelles, nous a permis d’identifier les moments et les espaces d’émer-gence et de repli de la communauté. La matérialisation de ces dynamiques se traduit par une appropriation ou une nouvelle création des ressources en eau, une réadaptation de l’infrastructure d’irrigation ou encore par la mobilisation opportuniste des règles de partage et de distribution de l’eau. A travers ces dynamiques conflictuelles, la communauté se donne à voir dans toute sa complexité et ses contradictions. Cette communauté présente un construit social non immuable et change selon les intérêts en vigueur et la référence mobilisée: sociale, territoriale, culturelle ou historique. La multitude de références et la mobilisation à géométrie variable des groupes dans les situations conflictuelles illustrent les recompositions sociales fortes vécues par la communauté d’irrigants. Elles montrent la fragilisation de l’enracinement de cette communauté suite aux interventions externes depuis le protectorat. Mots clés: Dynamiques conflictuelles, communauté d’irrigants, Bittit, Maroc

Syringomatous carcinoma: Case report of a rare tumor entity

Syringomatous carcinoma is a rare cutaneous neoplasm, most frequently situated on the face and scalp and histologically characterised by aninfiltrative pattern of basaloid or squamous cells, a desmoplastic stromal reaction and keratin filled cysts. We report the case of a 76-year-oldwoman who presented an ulcerative interscapular lesion measuring 3x4cm. After resection, the histological examinations of the specimens haveidentified a basal cell carcinoma. However, a local recurrence was observed 18 months later; histopathological findings showed a syringomatouspattern and neoplastic epithelial cells arranged in interconnecting cords with microcystic areas. Nests, cords, and tubules of the tumour extendedinto the dermis and into the adjacent muscle. Sclerosis of stroma around the cords was present. Tumour cells were not connected to the epidermis. The immunohistochemical analysis showed positivity for anti-CK7, AE1/AE3 and negativity for anti CEA and anti CK20. These histological and immunohistochemical analyses were consistent with the diagnosis of syringomatous eccrine carcinoma. Syringomatous carcinoma is an extremely invasive tumor, locally destructive and slowly growing adnexal tumour, derived from eccrine sweat glands. It is often mistaken, both clinically and microscopically, for other benign and malignant entities. The tumour recurrence is high due to extensive perineural invasion, butregional or distant metastases are rare. The local aggressive nature of the tumour and the high recurrence rate may necessitate mutilating procedures. Optimal treatment consists of a complete microscopically controlled surgical excision with clear surgical margins. Key words: Syringomatous carcinoma, histopathology, immunohistochemistry, differential diagnosi