Vol. 12 Issue 1
M.A. Bashir
We consider 4-dimensional CR-Submanifolds of constant curvature in the six-dimensional sphere. We proved that such submanifolds does not exist if the holomorphic distribution is parallel. We also proved that the integral submanifold of the holomorphic distribution is totally geodesic.
Hassan B. Amin
1H- and 13C-NMR chemical shifts are reported for a series of 18 imines, Ar(OH) (Br) CH=N-R , and 18 amines, Ar (OH) (Br) CH 2NH-R (R=CH], 'Pr, 'Bu , sBu, 'Bu or Ph), The amines were obtained by the reduction of the appropriate imine . The stereochemistry of imines was determined through their NMR spectral data. The imines were found to exist in solution as only a single E-isomer at ambient temperature, Interestingly , the carbon-13 chemical shifts for imino (CH=N) and benzylic (PhCH2) carbons are affected by alkyl groups (R), while the halo-substituted benzene ring has no effect on the chemical shift of the imine group , Substituent chemical shift (SCS) effects for - OH, - Br, CH = N-, CH2-NH , or - CHO are not additive at all positions,
Walid A. Abderrahman and Mohammed Rasheeduddin
The use of numerical techniques to define the detailed water budget analysis for each individual aquifer in a multi-aquifer system under steady state and transient conditions has not been well established in the literature. In this work, numerical analysis has been used to define the water budget for each individual aquifer in a multi-aquifer system in Greater Dhahran Area. A quasi-three dimensional simulation model of groundwater flow in the multi-aquifer system was developed using USGS-MODFLOW. The MODCELL program of the USGS was used to calculate the cell-by-cell flow volumes in each aquifer. The output data files from MODCELL were converted from binary to ASCII formats using CONYML utility module of the USGS. A special program was developed to make the output data files of MODCELL compatible with CONYML utility module.
The groundwater budget shows the importance of Umm Er Radhuma (UER) aquifer as a major water supply source to Dhahran area, as well as a potential recharge source to the Khobar and the Alat aquifers. The findings of the water budgeting are recommended to be used in improving the present and future water management and conservation schemes for the area . Similar techniques can be used to improve the groundwater use and management in other parts of the country as well as other arid regions.
Nasir A.Al-Darwish
An encryption scheme is randomized if many ciphertexts correspond to a given plaintext. In this paper we propose a simple and effective randomized public key encryption scheme. The scheme is based on the problem of finding a square root modulo n, where n is a product of two large distinct primes. The proposed scheme does not reveal any partial information and breaking it is as hard as factoring n. A randomized public key signature scheme is also proposed.
F.A.S.Soliman and S.A.Kamb
The purpose of this paper is to shed further light on the operating characteristics and limitations of tunnel diode amplifier circuits, particularly those with different doping concentrations. This has been achieved by a theoretical modeling, economical computer programs and experimental measurements. The behaviour of the tunnel diode operating at high frequency circuits, and the effects of material parameters and doping levels on their performance are presented and discussed. This leads to a better understanding of these devices and their limitations. It is found that the amplifier gain exceeds unity, and it increases with frequency reaching a peak at a certain value of the operating frequency, then it decreases at higher frequencies, down to a constant plateau. Results of the predicted, measured gain show that it depends on the device physical parameters and its material, circuit parameters, and operating conditions. The shape of the response curve of the amplifier circuit is a function of the dynamic negative conductance and also the resonance nature of the circuit.
W.A.Al-Mustafa, M.M. Limam, A.M.Falatah and A.A.El-Shall
The estimation of prediction optimum rates of fertilizer involves fitting some type of statistical model to yield data when several rates of fertilizer are applied. The objective of the work, reported here, was to evaluate four models (square root, quadratic, quadratic- plus- plateau and linear - plus - plateau) commonly used for describing the response of alfalfa (Medicago sativa L., c. v Hassawi) yield to phosphorus fertilizer. The evaluation involved 10 soil sites and 7 rates of fertilizer application. The four models indicated similar maximum yields, but there was considerable disagreement among the models when predicting economic optimum rates of P fertilization. Optimum rate of fertilizer P (mean all sites) as indicated by the four statistical models ranged from 113 to 412 kg P/ha. The quadratic statistical model did not give a valid description of yield response and predicted optimum rates of fertilizer that were too high. The quadratic- plus-plateau model, best described the yield response was observed in this study. The reason for preferring one statistical model over other deserves more attention than it has received in the past.
Ahmed H. Alfarhan
A study of four species of Cuscuta L. present in Saudi Arabia has been carried out. The study gives detailed morphological descriptions of three species, viz. C. campestris Yuncker, C. pedicellata Ledeb. and C. planiflora Tenore and their distribution in SaudI ArabIa. C. hyalina Roth., C. monogyna Vahl and the possible occurrence of few other species in the Kingdom are discussed briefly. A tentative Key is also provided for its identification.
Fawzi M. Karim
Recent extensive florisitic collections from U.A.E. especially the Masafi , Khor Fakkan and Hatta districts in the north east of the country, revealed the presence of 10 new taxa of the Flora of U.A.E. These are: Paracaryum intermedium Trichodesma ehrenbergii (Boraginaceae), Campanula erinus (Campanulaceae), Cuscuta chinensis (Cuscutaceae), Monsonia heliotropioides (Geraniaceae), Ficus johannis (Moraceae), Papaver decaisnei (papaveraceae) , Plantago albicans (Plantaginaceae), Rumex conglomeratus (Polygonaceae), Solanum surratense (Solanaceae).
A.K. Bashir, A.A. Abdalla E.S. Hassan, I.A. Wasfi, M.A. Amiri and T.A. Crabb
The extracts of the root of R. stricta growing wild in U.A.E. showed an antimicrobial activity. Using chromatographic techniques strictanol, tetrahydro secamine, akuammidine and rhazimanine were isolated. Their structure were elucidated using spectroscopic analysis techniques (including MS, 1H-NMR and 13C-NMR). The antimicrobial activity of the isolated alkaloids and their MIC were determined.
Faisal M. Abou-Tarboush
Inbred normal adult CBA mice were used to investigate the possible teratogenic and other effects of Hiconcil (Amoxicillin) on foetuses of females treated intraperitoneally (ip) once each day from day 7 to 12 of pregnancy. The prenatal administration of Hiconcil at 500 or 650 mg.kg body weight resulted in both teratogenic and toxic effects on foetuses of treated mothers. Such effects comprised the development of abnormal hindlimbs and tails. However, the drug was safe to treated dams at all dose levels and at all times during gestation.