ZOOPLANKTON BIOMASS IN THE MOST NORTHERN TIP OF THE GULF OF AQABA, A CASE STUDY

T. Al-Najjar and M. Rasheed

This work aims at studying zooplankton biomass in the oligotrophic water of the most northern tip of the Gulf of Aqaba, Red Sea. Zooplankton were sampled twice at two different days during September 2003 from three sites at 25 and 50m depths. Stations were selected near areas with high human activities at the northern coast of Aqaba. Slight differences between 25m and 50m water depth were found at the different selected sites. A notable increase was observed in surface zooplankton biomass inside the yachting club pool compared to the other locations which attributed to human activities at this station. However, the results indicated that the distribution of zooplankton biomass at the most northern tip of the Jordanian sector of the Gulf of Aqaba was fairly homogeneous. Fractions of the zooplankton biomass of the studied areas were distributed ascendingly with an increase in the fraction size of the following order 100-200, 200-500, 500-1000 and >1000 µm. It is concluded that, anthropogenic activities at the northern tip of the Gulf of Aqaba, which results in higher nutrient levels, may subsequently increase the biomass of zooplankton in the sea water.

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COMMUNITY STRUCTURE OF THE FAMILY LABRIDAE ALONG THE JORDANIAN COAST, GULF OF AQABA, RED SEA

M.A. Khalaf, F. Al-Horani, R. Manasrah and S. Al-Rousan

The spatial distribution and community structure of the family Labridae were studied at different depths and sites along the Jordanian coast of the Gulf of Aqaba in the seagrass and coral reef habitats. A total of 44 species of labrid fish were observed during the 187 visual census performed in seventeen sites. Out of the 44 labrid fish species encountered, 4 species including Paracheilinus octotaenia, Thalassoma rueppellii, Cirrhilabrus rubriventralis and Coris caudimaculata accounted for 64% of all individuals counted. Fishes were more abundant at 12 m depth in coral dominated sites, while a lower abundance was found in reef flat and seagrass sites. This was attributed to a higher shelter, structural complexity and food availability in the coral reef sites. The coral reef habitat had significantly higher species richness than the seagrass habitat at 6 and 12 m depths combined (p<0.0001). Within coral reef sites, the deeper transects had significantly higher species richness than those on the reef flat. It was concluded that differences among reefs and habitats were the most important components of variability in the abundance and species richness of the family Labridae along the Jordanian coast of the Gulf of Aqaba.

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LES SELS NUTRITIFS ET LE PHYTOPLANCTON SUR LA CÔTE SUD DU LIBAN : EVALUATION D’INDICES ECOLOGIQUES

M. Abboud-Abi Saab, M. Fakhry, M. -T. Kassab et N. Mattar

Cette étude a été effectuée dans le but d’utiliser des indices écologiques pour l’estimation de la qualité des eaux côtières. Des prélèvements d’eau mensuels ont été réalisés entre septembre 2000 et décembre 2001, dans 4 stations situées en zone littorale de l’extrême sud de la côte libanaise et présentant des conditions géographiques et écologiques différentes. Des paramètres hydrologiques, hydrobiologiques et biologiques ont été analysés.
Les résultats ont montré que les températures ont varié entre 16,2 et 30°C, les salinités entre 38,87 et 39,57, les taux des orthophosphates entre 0,01 et 0,68 µmol/L et les teneurs en nitrite et en nitrate ont varié successivement entre 0,01 et 0,47 µmol/L et 0,02 et 11,64 µmol/L. Le rapport N/P a été loin de la valeur normale dans toutes les stations et ceci est dû au fait que les stations sont littorales et souvent soumises aux différentes agressions continentales ; par conséquent, il ne peut être considéré dans les eaux littorales comme seul indicateur d’un écosystème marin bien équilibré. La diversité spécifique (indice de Shannon) a varié entre 0,8 et 4,6. Les stations relativement peu polluées ont eu des indices de diversité élevés, alors que celles fortement polluées, ont eu des indices plus faibles. Cet indice pourra être considéré dans certaines conditions comme un critère pour l’estimation du déséquilibre dans le milieu. Il paraît bien que l’étude de l’aspect qualitatif du phytoplancton et de l’évolution du nombre de cellules reste un facteur indispensable pour estimer le niveau d’eutrophisation dans le milieu littoral et côtier.

This study uses ecological indicators for the assessment of coastal water quality. Four stations having different geographical and ecological conditions were chosen along the coastal area of south Lebanon. Water samples were collected monthly from September 2000 to December 2001. Hydrological, hydrobiological and biological parameters were measured.
Results showed that temperatures varied between 16.2 and 30°C, salinity between 38.87 and 39.57, orthophosphates between 0,01 and 0,68 µmol/L, nitrite and nitrates between 0,01 and 0,47 µmol/L et 0,02 and 11,64 µmol/L successively. The ratio N/P is far from the normal value, in the 4 stations. This is due to the fact the stations are coastal and subject to continental influence. Hence they could not be considered as the only indicator for a well-equilibrated marine ecosystem. Specific diversity (Shannon index) varied between 0.8 and 4.6. Stations with a low pollution have a high diversity while highly polluted stations have a lower diversity. The diversity index, within certain conditions can be considered as one criteria to estimate the equilibrium in the environment. Qualitative and quantitative study of phytoplankton are still an important factor in estimating the level of eutrophication in the littoral environment.

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WIND AND WAVE DATA ANALYSIS FOR THE LEBANESE COASTAL AREA-PRELIMINARY RESULTS

N. Kabbara

In this paper, a statistical analysis on wind and wave data measurements obtained during a two-year period (2000-2003) is presented. Measurements are produced by the Lebanon Meteorological Network of the Ministry of Public Work and Transport operated by the Department of Meteorology at Beirut Airport. Although the two-year period is short for a statistical descriptive analysis of the local wind and wave climate, the obtained results presented in this paper reveal the general characteristics of wind and wave climate in the study area.

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INVENTORY AND MANAGEMENT OF LEBANESE SOILS INTEGRATING THE SOIL GEOGRAPHICAL DATABASE OF EURO-MEDITERRANEAN COUNTRIES

T . Darwish, I. Jooma, M. Awad, M. AbouDaher, and J. Msann

Land management and degradation are among central issues in the 21st century. Several international and local organizations deal with land vulnerability to desertification and have elaborated databases addressing soil information and thematic mapping. Among these are the Global and National Soil and Terrain Database (SOTER), the FAO dbase, the Georeferenced Soil Database for Europe. These procedures are workable at different scales. The FAO-dbase is a soil profile and laboratory database. The remaining methodologies are not strictly a cartographic tool but conceptual models with computerized structure of the data. But, while SOTER uses the available soil maps as support to build the database, the Soil Geographical database of Euro-Mediterranean Countries aims at preparing a geographic database by relegating the problem of the cartographic representation of data to a secondary position.
Extremely variable landform, lithology, climate and vegetation cover characterize the east Mediterranean including Lebanon. From the coastal strip to the high mountains different soil types are spread like Fluvisols, Cambisols, Vertisols, Luvisols, Regosols, Leptosols, and Calcisols. To build the soil database integrating the Euro-Mediterranean methodology, additional information was gathered from old studies of Lebanese soils run between 1950 and 1975. To complement the missing soil information reflecting the great variability of soil association, substantial fieldwork was recently undertaken for soil description and sampling. As a result, a new soil map of Lebanon at 1:1 M. scale was produced. The soil units were mapped using the lithology-landform association as separation criteria for the identification of soil entities. Both dominant and small typological units were maintained to reflect soil diversity and the need for differential land management. Beside the geometric dataset, the semantic dataset contains information on soil geomorphology, main physical and physico-chemical characteristics including land use, management practices and related problems. In this paper the work implemented to build a small scale, but comprehensive, soil database for Lebanon is reviewed. The paper discusses the database suitability for the assessment of current agricultural and environmental practices in relation to climatic conditions and soil parameters. A detailed analysis of the state and impact of land degradation, potential of land resources in view of geomorphology, land capability, and land vulnerability to desertification is presented.

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CARTOGRAPHIE DE LA DENSITE DE DRAINAGE PAR UNE CLASSIFICATION STRUCTURALE DES INFORMATIONS SPATIALISEES : APPLICATION DE LA METHODE OASIS A UNE REGION REPRESENTATIVE DU LIBAN

R. Bou Kheir et M.-C. Girard

La cartographie de la densité de drainage dans une région représentative du Liban en un temps relativement court et à faible coût a été obtenue en traitant la carte des réseaux hydrographiques à l'échelle de 1/50 000 suivant la classification structurale OASIS (Organisation et Analyse de la Structure des Informations Spatialisées). En adoptant cette méthodologie, des fenêtres de taille différente ont été parcourues de façon à optimiser le résultat (ici fenêtre de 15 x 15 pixels) qui permet d'avoir des plages cartographiques compactes et organisées. Trois classes de densité ont été distinguées : faible (25 % de la région étudiée), moyenne (44 %) et forte (31 %). L’évaluation de la qualité de la carte obtenue nous indique que la plus grande partie de la région étudiée (73 %) est bien classée.
La carte de la densité de drainage constitue un paramètre d'entrée dans les différents modèles d'érosion hydrique des sols qui représentent des outils d'aide à la mise en œuvre des plans futurs de conservation des sols.

Mapping of drainage density in a representative region of Lebanon in a relatively short time and at a low cost has been obtained by treating the map of drainage networks at a scale of 1/50 000 following the structural classification OASIS. According to this method, windows of different size were utilized and a window of 15 x 15 pixels has been chosen in order to have polygons characterizing the density compact and organized. Three classes of density were distinguished: low (25% of the study area), moderate (44%) and high (31%). Evaluating the quality of the obtained map indicates that the biggest part of the study area (73%) is well classified.
The drainage density map constitutes an input parameter for different soil-water erosion models, which represent relevant tools in order to put into evidence future plans of soils conservation.

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Basic Sciences, Engineering and Technology

NOUVELLE RELATION CONTRAINTE PARIÉTALE-DÉBIT POUR UN ECOULEMENT NON PERMANENT DE FLUIDES NON NEWTONIENS EN CONDUITE DÉFORMABLE POREUSE À PAROI VISCOÉLASTIQUE ET ANISOTROPE

K. Gueraoui, M. Taibi, A. Mrabti, G. Zeggwagh et Y. M. Haddad

Le but du présent travail est l’élaboration d’une relation contrainte pariétale-débit dans le cas des écoulements non permanents de fluides non newtoniens, à faible nombre de Womersley, dans des conduites déformables poreuses à parois viscoélastiques et anisotropes.
L’utilisation de cette relation a permis de résoudre directement le système de la paroi et le système intégral de l’écoulement. Alors l’évolution des profils de débit et de la contrainte pariétale a été analysée en fonction de l’indice de comportement, de la consistance du fluide, de l’anisotropie et du coefficient de filtration.
Cette étude, considérée comme une importante étape dans la modélisation des écoulements sanguins, peut s’adapter à d’autres applications industrielles.

The goal of the present work is to elaborate a relationship between wall shear stress and flow rate in porous anisotropic and viscoelastic tubes, for pulsatile flows of non Newtonian fluids. This contribution is done for the case of small values of Womersley parameter.
The use of this relationship enabled to directly solve the wall and integral equations. Then the influence of the power law index, the fluid consistency, the filtration coefficient and the anisotropy of the wall on the flow rate and the wall shear stress was analyzed.
This study, considered as a step in modeling of flow in blood vessels, may also contribute to other important fields such as water desalination or gel filtration.

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MODELLING OF A CURRENT CONTROLLED OSCILLATOR

R. Maghrebi, M. Masmoudi

This paper proposes a behavioral model for a current controlled oscillator (CCO) which will be an element of an analog behavioral library devoted to A/D converters. The analog block model will be associated with a digital block model in order to validate the conversion algorithm of a multi-slope analog to digital converter according to a proposed methodology. Results from simulations carried out using VHDL prove the validation of the CCO and are in good agreement with those obtained by electrical simulations and experimental Silicon prototypes.

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ETUDE AB INITIO DE L’EFFET D’INSERTION DE L’HYDROGÈNE SUR LES PROPRIÉTÉS MAGNÉTIQUES ET CHIMIQUES DANS LES PHASES DE LAVES : CAS DE ZrFe2

S. Matar, M. Nakhl, M. Zakhour et N. Ouaini

Les propriétés électroniques et magnétiques de la phase cubique de Laves ZrFe2 et de son hydrure ZrFe2H3,5 sont étudiées à l’aide d’un outil de modélisation théorique dans le cadre de la théorie de la fonctionnelle de la densité DFT dans une implémentation locale de la densité de spin (LSDA). L’objectif principal est d’évaluer l’importance de l’effet de la pression chimique provoquée par l’insertion de l’hydrogène au sein de la maille de l’alliage métallique. Les changements observés suite à l’insertion de l’hydrogène pour les moments magnétiques et les propriétés de liaison chimique résolue en spin sont discutés et une confrontation avec l’expérience a été effectuée. Les résultats obtenus sont comparés avec ceux qui ont été obtenus dans le cas de YFe2 et de son hydrure.

The electronic and magnetic properties of the cubic Laves phase ZrFe2 and of its hydride ZrFe2H3.5 are studied within the density functional theory (DFT) in its local spin density approximation (LSDA) for the purpose of assessing the interplay between chemical pressures versus chemical bonding effects due to the insertion of hydrogen. The observed changes of the magnetic moments and of the spin resolved chemical bonding properties upon the insertion of hydrogen are discussed. A comparison with experiment and with data for formerly studied YFe2 and its hydride is carried out.

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INFLUENCE DU BROYAGE ENERGETIQUE SUR LES PROPRIETES STRUCTURALES ET MAGNETIQUES DES INTERMETALLIQUES GdNi2 ET GdCu2

M. Nakhl , B. Chevalier, M. Zakhour , N. Ouaini et J.-L. Bobet

Les intermétalliques binaires GdNi2 et GdCu2 ont été soumis à un broyage mécanique à l'aide d'un broyeur planétaire. Les produits de broyage ont été caractérisés par diffraction X sur poudre, microscopie électronique à balayage et par des mesures d'aimantation. Ce traitement n’a pas entraîné une amorphisation des composés initiaux comme le confirment les analyses par diffraction X. D'autre part, le broyage ne modifie pas le comportement ferromagnétique de GdNi2 mais induit une transition antiferromagnétique
(TN = 40 K) ->''verre de spins'' (Tf = 26 K) pour GdCu2.

GdNi2 et GdCu2 were submitted to a high-energy ball-milling using a planetary ball-miller. The products were investigated by X-ray powder diffraction, electron microscopy and magnetic measurements. The X-ray diffraction patterns of these products did not show any amorphization after the milling treatment. Furthermore, this treatment preserves the ferromagnetic behavior of GdNi2 but induces a magnetic transition from antiferromagnetism (TN = 40 K) to spin glass (Tf = 26 K) for GdCu2.

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ETUDE DE L’EFFET THERMIQUE DÛ À L’EXPOSITION AUX RAYONNEMENTS D’UNE STATION D’EMISSION GSM

Mohamed Rammal, Talal Sahili, Kamal Sabbah et Fatmé Jebai

L’effet thermique de rayonnement de stations d’émissions GSM sur le corps humain est étudié. La méthode des différences finies est utilisée pour simuler les antennes d’émissions et le corps humain et les résultats d’exposition au champ électromagnétique d’un cas réel sont présentés et discutés.

In this paper the thermal effect of GSM base station exposition is presented. Finite difference time domain FDTD method has been used to simulate a typical exposition case for human body behind a GSM station. Obtained results have been presented and discussed.

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VARIATIONS IN HUMAN AND BOVINE SURFACE ENAMEL ACID ETCHING PATTERNS AND RESIN PENETRATION: A SCANNING ELECTRONIC MICROSCOPY IN-VITRO STUDY

Fayez K. Saleh

The aim of this study was to evaluate and compare the different acid etching patterns and resin penetration to human and bovine enamel as indicator of their bond strength properties. Forty human and forty bovine incisors were tested in the shear and tensile bond strength modes using a light-cured composite resin "Reliance Light Bond". Bond strength tests were conducted on a universal testing machine installed to a special computer transducer where bonding failure data were recorded. Statistical analysis of the results revealed a highly significant difference between the shear and tensile bond strengths of human enamel as compared to that of bovine teeth. Scanning Electron Microscopic examination of the enamel surfaces were carried out before and after etching, then resin remnants penetration to enamel after bond failure were also assessed. The results showed a high variability in the etching patterns and penetration depth of the resin tags to human and bovine enamel surfaces which are attributed to the difference in the micro-topography of their enamel surfaces. Despite the overall differences, the consistency of the bovine bonding strength properties suggests their continuous use as a substitute for their human counterparts in similar studies.

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ON THE INVERSE LIMIT OF FINITE DIMENSIONAL SEMISIMPLE LIE ALGEBRAS

Nadine Ghandour and Anwar El Lahham

This study proves that every finite dimensional homomorphic image of a prosemisimple Lie algebra L =LimLn (n E N) is also semisimple in the case when the dimensions of all simple factor ideals of all Ln are bounded.

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