Vol. 19 Issue 3
A. Sh. Abdu, A. A. Abahussain, W.K. Al-Zubari, M. Abdulraheem and M.N.A. El-Din
It is widely accepted, that desertification is simply land degradation in the dry lands due to a number of factors including climatic variations and human activities. The Arab region is particularly vulnerable to several development problems that are caused by mismanagement of natural resources of its marginal dry lands. This paper provides a brief synthesis of the rapid population increase and the expanding urbanization, loss of productive land and biodiversity and the deterioration of the water resources in the Arab region. The consensus of opinion indicates that resources management practices have been sustainable. That induced disruption of social systems, ecological degradation, increasing population pressure and poverty. The evidence indicates inherent lack of appropriate government policies and weak institutions. Because desertification problems are not addressed systematically and because these time-delayed problems are difficult to handle in the future, they need to be addressed as policy issues now. The discussion highlights the need to consider a wider range of collective and coordinated policies at the level of the Arab region to combat the problems of desertification.
M. Dorgham and N.E. Abdel-Aziz
The qualitative and quantitative dynamics of the tintinnid community in Doha Harbour (Arabian Gulf) were studied monthly for 13 months. The results showed that the harbour was characterized by a tintinnid community with a comparatively great number of species (76 spp.) and high diversity (diversity index: up to 2.96). The standing crop appeared to be very low (35-2529 cells/m3) showing a bimodal peak of abundance in February and November at a temperature of 18.4- 21.5°C. A few species were responsible for the bulk of the tintinnid abundance, while frequently existing species attained temporary abundance. The biometric measurements reflected a wide range of variations among different species in lorica length (34.9- 297.5 µm), oral diameter (20- 97µm) and volume (0.06 x10^5 - 15.13 x 10^5 µm3). Significant correlation was found between tintinnid abundance and temperature, nitrite, nitrate and phosphate, while with dissolved oxygen, ammonia and silicate the correlation was not significant.
A.I. Mukolu
The room temperature variation of surface conductance of tellurium (Te) films with thickness has been studied. The measurements were performed in an atmosphere of oxygen (O2) or oxygen bubbled through hydrofluoric acid (HF(O2)). Tellurium films of thicknesses 500, 1000, 1500 and 2000A were deposited by thermal evaporation ata vacuum maintained at about 10-5 torr during the evaporation process. Some of the Te samples were annealed at 200 °C for 20 minutes. For the current (I)- voltage (V) measurements, the two-point probe configuration was adopted using aluminium (Al) electrodes. The surface conductance at zero bias was determined from the I-V data.
The results reveal that the surface conductance of Te films is enhanced by the adsorption of O2, while the adsorption of HF(O2) reduces the surface conductance of the samples. The evaluated increase in surface conductance at zero bias, due to the adsorption of O2 ranges from 92% to 113% as the thickness of the films varied from 500 to 2000A. Also, the value of the reduction in surface conductance due to the adsorption of HF(O2) is between 27% and 33% as the thickness of the films varied from 500 to 2000A. The surface conductance of all the samples investigated increases exponentially with thickness. Finally, the surface conductance of as deposited Te films is higher than that of heat-treated Te samples.
M. Almulla, M. Al-Haddad and H. Loeper
In this paper, implementation issues of concurrent object-oriented programming using Ada 95 are addressed. Ada is not a pure object-oriented language; in order to make it so, a uniform template for structuring object classes is proposed. The template constitutes a basis for an Ada-based preprocessor language that handles concurrent object-oriented programming. The preprocessor accepts Ada-like object-oriented programs (object classes, subclasses, and main program) as input and produces Ada 95 concurrent object-oriented program units as output. The preprocessor language has the advantage of adding a new component to the class specification called the protocol, which specifies the order for requesting methods of an object. The preprocessor also touches on the extensibility of object classes issue. It supports defining class hierarchies by inheritance and aggregation. In addition, the preprocessor language supports the re-use of Ada packages, which are not necessarily written according to the object-oriented approach. The paper also investigates the definition of circular dependant object classes and proposes a solution for introducing a collection of classes.
W. Aboul-Naga
Eutrophication is the most serious problem in Lake Mariut. Lake Mariut is one of the North Nile Delta lakes. It is closed and unconnected directly with the sea. Its waters are discharged into the sea via El-Mex pumping station. Its area has been reduced due to land reclamation and the construction of some fish farms. Hydrographical and nutrient salts studies covering five seasons from January 1996 (winter) to April 1997 (spring) showed increasing quantities of inorganic and organic nutrients, which led to pronounced change in the quantitative and qualitative structure of Lake Mariut. Originally, Lake Mariut had a basin of quite different biological properties, one part mostly covered by Potamogeton pectinatus (macrophytes), while another part that recieved discharge from Alexandria city was plankton dominated and of extremely high productivity. Primary production measured as chlorophyll-a ranged between 0.78 and 1.91 g m-3. As a result of the extensive input of nutrients from Alexandria city, the enclosed nature of the lake and the shallowness of the water, heavy algal blooms and domination of plankton existed. The lake receives heavy industrial, domestic and agricultural wastewaters from different sources. The chlorosity values showed a narrow range variation between 1.139 and 2.009 g/l. The most affected part of the lake is its north western sector (lake proper). The state of deterioration of this basin is so bad that the intensive production led to remarkable reduction of dissolved oxygen (~1 mg/l) and the appearance of hydrogen sulphide up to 14.4 mg l-1. The study of hydrochemical variables was supported by hydrographical data (temperatures, pH, Eh and transparency). Very high values of phosphate (18.3 mol/l) , polyphosphate (11 mol/l) , ammonia (41 mol/l), nitrite (2.4 mol/l), nitrate (36 mol/l), and silicates (157 mol/l) were recorded.
N. Al-Zoreky
Popular types of Yemeni honey were evaluated for their physical and chemical properties. Fourteen parameters were determined in tested honey: moisture, pH, acidity (free, lactone and total), ash, electrical conductivity (E.C. ), hydroxymethyl furfural (HMF), proline, Diastase number(Goth scale), reducing sugar, sucrose, glucose and fructose. Results indicated that Buckthorn (Zizyphus spina-christi, sidir) honey had the highest (P<0.05) means in ash and E.C. Significant sucrose contents (P<0.05) and lowest reducing sugar (%) were the main features of sugar-fed bees' honey, 'sugar honey'. Acacia spp. Joney (Acacia honey) was different (P<0.05) from other types in total acidity, proline and fructose. It could be concluded that floral Yemeni honey types were in conformity with honey regulations laid down by many regional and international standard organizations; e.g. the Saudi Arabian standards and Codex Alimentarius Commission (FAO/WHO).
F. Radwan
A reduction procedure for decomposing a Cartesian tensor of rank into its irreducible parts is given. The numbers of different irreducible parts of the sixth rank Cartesian tensor are calculated. The number of independent contractors of sixth rank Cartesian tensor is computed. The scalar normalized irreducible parts of sixth rank Cartesian tensor are presented. Examples of different symmetry of sixth rank tensors are given.
D. Al-Eisawi
Two new species Crocus naqabensis and Romulea petaraea, Iridaceae, are described from Jordan. Crocus naqabensis differs from the closely related to C. pallasii by having reduced tunics that are not forming a neck, white glabrous throat and chromosome number 2n = 14. Romulea petaraea has been collected from the mountains of Petra and differs from Romulea bulbocodium in flower colour, shape and insertion of perianth segments as well as in the narrower leaves and distribution that is restricted on sandy rocks. R. petraea has totally dark purple flowers that differ from R. phoenicia which has violet flowers with darker veins, yellow at the base of the throat, in addition to different habitat.
D. Larbaoue
This study was conducted to evaluate nutritional status with its different forms: normal, wasting, stunting and underweight by using respectively the anthropometric indices P/T, T/A and P/A in 2645 children under five years of age in the west of Algeria. With percentages below -2 standard deviation from the WHO reference median values, the prevalences of wasting, stunting and underweight are respectively 18.7%, 35.3% and 17.2%. This study concluded that the majority of malnourished children had illiterate mothers or mothers with low educational levels, lived in numerous or poor families. The health consequences of height prevalence of malnutrition in this study are severe, there is an urgent need to accelerate significant economic development until optimal child growth and development are ensured for the majority of children in Algeria.
A.M. Al-Moshileh and M.M. Kawas
The purpose of this study is to evaluate the effect of partial protection on natural vegetation cover of Ghada range reserve in Unayzah, KSA, and to focus on the participation of that on the natural vegetation cover development. This study had clearly pointed the positive effect of partial protection of the vegetation cover by increasing the number of plant species, the density of both annuals and perennials, and changing of plant cover structure. The plant species numbers increased from 13 to 21 in unprotected and protected area respectively. This increment percentage was about 62%, and was associate with increasing the number of plant families from 8 to 11. Also the plant cover was increased by 78% in protected area while it was only 13% in non-protected area. The plant density also increased from 2398 to 6824 plant/ha in unprotected and protected area respectively. This confirms the positive effect of conservation and protection on plant natural vegetation cover.