APPORT DE L’IMAGERIE DANS LES DACRYOCELES

The dacryocele is a non regressive cystic dilation often met in the adult. The goal of this work is to point out the interest of the imagery in the diagnosis of this affection. Bringing back to us a series of 7 cases colliged to the service of radiology August 20. One notes a female prevalence with an average age 35 years. Clinically, one often found a tumefaction compared to the lachrymal bag. The imagery showed the presence of a formation of liquid density on the level of the canthus intern, limited well, being raised slightly in periphery by the product of contrast with a widening of the lacrymo-nasal channel. The dacryocèle, rare benign affection, can be secondary with an acquired or congenital mechanical obstruction of the lacrymo-nasal channel. The imagery, thanks to echography and to the dacryoscanner, makes it possible to make the positive diagnosis, to carry out a precise organic assessment, to seek its etiology and to eliminate a tumoral origin.La dacryocèle est une dilatation kystique non régressive souvent rencontrée chez l’adulte. Le but de ce travail est de rappeler l’intérêt de l’imagerie dans le diagnostic de cette affection. Nous rapportant une série de 7 cas colligés au service de radiologie 20 AOUT. On note une prédominance féminine avec une moyenne d’âge de 35 ans. Cliniquement, on retrouvait souvent une tuméfaction en regard du sac lacrymal. L'imagerie a montré la présence d’une formation de densité liquidienne au niveau du canthus interne, bien limitée, se rehaussant faiblement en périphérie par le produit de contraste avec un élargissement du canal lacrymo-nasal. La dacryocèle, affection bénigne rare, peut être secondaire à une obstruction mécanique acquise ou congénitale du canal lacrymo-nasal. L’imagerie, grâce à l’échographie et au dacryoscanner, permet de faire le diagnostic positif, d’effectuer un bilan lésionnel précis, de rechercher son étiologie et d’éliminer une origine tumorale

Design procedures of reinforced concrete framed buildings in Nepal and its impact on seismic safety

The present paper analyses the design procedure and its impact on seismic safety of the structures. For this, a representative reinforced concrete frame building (WDS) is designed and the results are compared with similar buildings detailed with: i) Current Construction Practices (CCP); ii) the Nepal Building Code (NBC) and iii) the Modified Nepal Building Code (NBC+) recommendations. The seismic performance evaluation is done with global strength, inter-storey drift and displacement of the structures. Likewise, the sensitivity of the structural and geometrical parameters of the RC frame building is studied through nonlinear analysis. The study parameters considered for parametric analysis are column size, beam size, inter-storey height, bay length, bay width, and compressive strength of concrete. The results show that the influence on the structural behaviour, particularly by variation in column size and inter-storey height. Additionally, the influence of the seismic zone factor on reinforcement demand of the structure is studied. The result shows that structures designed for high to medium seismic hazard demands double the reinforcement in beams compared to structures in low seismic zone

A New Approach in the Development and Analysis of the Landslide Susceptibility Map of the Hillslopes of Bujumbura, Burundi

As in other hilly and mountainous regions of the world, the hillslopes of Bujumbura are prone to landslides. In this area, landslides impact human lives and infrastructures. Despite the high landslide-induced damages, slope instabilities are less investigated. The aim of this research is to assess the landslide susceptibility using a probabilistic/statistical data modeling approach for predicting the initiation of future landslides. A spatial landslide inventory with their physical characteristics through interpretation of high-resolution optic imageries/aerial photos and intensive fieldwork are carried out. Base on in-depth field knowledge and green literature, let's select potential landslide conditioning factors. A landslide inventory map with 568 landslides is produced. Out of the total of 568 landslide sites, 50 % of the data taken before the 2000s is used for training and the remaining 50 % (post-2000 events) were used for validation purposes. A landslide susceptibility map with an efficiency of 76 % to predict future slope failures is generated. The main landslides controlling factors in ascendant order are the density of drainage networks, the land use/cover, the lithology, the fault density, the slope angle, the curvature, the elevation, and the slope aspect. The causes of landslides support former regional studies which state that in the region, landslides are related to the geology with the high rapid weathering process in tropical environments, topography, and geodynamics. The susceptibility map will be a powerful decision-making tool for drawing up appropriate development plans in the hillslopes of Bujumbura with high demographic exposure. Such an approach will make it possible to mitigate the socio-economic impacts due to these land instabilitie

A New Approach in the Development and Analysis of the Landslide Susceptibility Map of the Hillslopes of Bujumbura, Burundi

As in other hilly and mountainous regions of the world, the hillslopes of Bujumbura are prone to landslides. In this area, landslides impact human lives and infrastructures. Despite the high landslide-induced damages, slope instabilities are less investigated. The aim of this research is to assess the landslide susceptibility using a probabilistic/statistical data modeling approach for predicting the initiation of future landslides. A spatial landslide inventory with their physical characteristics through interpretation of high-resolution optic imageries/aerial photos and intensive fieldwork are carried out. Base on in-depth field knowledge and green literature, let's select potential landslide conditioning factors. A landslide inventory map with 568 landslides is produced. Out of the total of 568 landslide sites, 50 % of the data taken before the 2000s is used for training and the remaining 50 % (post-2000 events) were used for validation purposes. A landslide susceptibility map with an efficiency of 76 % to predict future slope failures is generated. The main landslides controlling factors in ascendant order are the density of drainage networks, the land use/cover, the lithology, the fault density, the slope angle, the curvature, the elevation, and the slope aspect. The causes of landslides support former regional studies which state that in the region, landslides are related to the geology with the high rapid weathering process in tropical environments, topography, and geodynamics. The susceptibility map will be a powerful decision-making tool for drawing up appropriate development plans in the hillslopes of Bujumbura with high demographic exposure. Such an approach will make it possible to mitigate the socio-economic impacts due to these land instabilitie

Infrared spectra of annite in the interlayer and lattice vibrational range

Fe-rich trioctahedral micas hydrothermally synthesized are characterized by infrared spectroscopy, the spectra are collected from powder suspensions. In the lattice vibrational range, the vibrations Si–Onb, Si–Ob, Al–Onb, Al–O–Si, Si–O–Si and delta OH are all characterized by the presence of doublets in the annite KBr-absorption spectra. In agreement with observations in the vibrational range of the OH-groups, this feature is interpreted to reflect the chemical heterogeneity of the octahedral and tetrahedral layers, imposed by crystallochemical constraints. With increasing Al content of the micas along the annite-siderophyllite join, the evolution of the bands shows that Al and Si become more ordered in the tetrahedral layer. In the interlayer vibrational range, the OH-annite end-member shows clearly five of the six predicted vibrations. The bands occuring at 66 cm-1 and at 120–130 cm-1 are related to vibrations involving interlayer cation, whereas the band observed at 152 cm-1 is assigned to basal oxygen vibrations around the interlayer cations. The Tschermak substitution (starting from the annite end-member) increases the misfit between the octahedral and tetrahedral layers. However, variations of fO2 do not affect significantly the band frequencies resulting from motions related to the interlayer cations, suggesting that the geometry of the interlayer site is not significantly disturbed by variation of the Fe3+/Fe2+ ratio in annite

Superficial structures cartography of the Essaouira basin under ground (Morocco), by small refraction seismic: contribution of the static corrections in the reinterpretation of the speeds variations.

The static corrections are a necessary step in the sequence of the seismic processing. This paper presents a study of these corrections in the Essaouira basin. The main objective of this study is to calculate the static corrections by exploiting the seismic data acquired in the field to improve the deep structures imaging. It is to determine the roof and the basis of the superficial layers which constitute the weathered zone while calculating the delays of seismic wave’s arrivals in these layers. The purpose is to cancel the effect of the topography and the weathered zone, in order to avoid any confusion when the seismic and geological interpretation. The results obtained show the average values of the static corrections varying between - 127 and 282 ms (double time), with existence of high values by location, particularly in the Eastern and North-Eastern of the basin, which meant the presence of altered zone with irregular topography and whose thickness and speeds vary laterally. In effect the variations of velocities in the fifty meters from the surface may introduce significant anomalies in seismic refraction, with heavy consequences when the interpretation or the drilling establishment. These variations are mainly due to lateral changes in facies and variations in the formations thickness. The calculation of the static corrections, revealed high values at certain areas (East and North-East), which will enable us to better orient the future campaigns in these zones. It is therefore necessary to concentrate the seismic cores drillings and the small refraction seismic profiles by tightening the seismic lines meshes in order to have the maximum values of static corrections and thereafter a better imaging of the reflectors

Le décollement de rétine : Aspects échographiques

Objectif :Préciser les aspects échographiques des décollements de la rétine.Matériels et méthodes :Mise au point basée sur une revue de la littérature et illustrée par des cas émanant de la pratique quotidienne d’échographie dans notre formation. Des patients explorés pour des indications ophtalmiques diverses et dont l’échographie a objectivé un décollement rétinien. L’examen a été réalisé par une sonde de 11 MHz avec un échographe GE.Résultats :35 patients ont été explorés. Les signes cliniques étaient dominés par une baisse de l’acuité visuelle d’installation rapide. Les étiologies sont diverses dominées par le décollement tractionnel chez le diabétique et le décollement post traumatique. L’examen échographique a permis de poser le diagnostic de décollement avant la clinique dans les cas où l’exploration du segment postérieur était impossible à l’examen clinique.Conclusion :L’échographie oculaire s’avère essentielle en cas de suspicion de décollement de rétine, notamment en cas des milieux antérieurs et/ou postérieurs impurs. Elle devrait être demandée sans délai pour une prise en charge rapide, adaptée et efficace

Superficial structures cartography of the Essaouira basin under ground (Morocco), by small refraction seismic: contribution of the static corrections in the reinterpretation of the speeds variations.

The static corrections are a necessary step in the sequence of the seismic processing. This paper presents a study of these corrections in the Essaouira basin. The main objective of this study is to calculate the static corrections by exploiting the seismic data acquired in the field to improve the deep structures imaging. It is to determine the roof and the basis of the superficial layers which constitute the weathered zone while calculating the delays of seismic wave’s arrivals in these layers. The purpose is to cancel the effect of the topography and the weathered zone, in order to avoid any confusion when the seismic and geological interpretation. The results obtained show the average values of the static corrections varying between - 127 and 282 ms (double time), with existence of high values by location, particularly in the Eastern and North-Eastern of the basin, which meant the presence of altered zone with irregular topography and whose thickness and speeds vary laterally. In effect the variations of velocities in the fifty meters from the surface may introduce significant anomalies in seismic refraction, with heavy consequences when the interpretation or the drilling establishment. These variations are mainly due to lateral changes in facies and variations in the formations thickness. The calculation of the static corrections, revealed high values at certain areas (East and North-East), which will enable us to better orient the future campaigns in these zones. It is therefore necessary to concentrate the seismic cores drillings and the small refraction seismic profiles by tightening the seismic lines meshes in order to have the maximum values of static corrections and thereafter a better imaging of the reflectors