Vol. 17 Issue 1
Charles S. Bakheit and Elfadl K. Elsheikh
We derive expressions for lim Prob (Z = i, Z+2 = j) for a semi-Markov process with a finite number of states. As an application of the results, we obtain the autocorrelation function of the process of recorded current flowing through a single channel, for two Markovian models of the behavior of drug-operated ion-channels. The additional information provided by the autocorrelation function would facilitate the task of identifying the model which is more consistent with the observed record.
Nagy S. Botros
Acid-sulphate alteration comprising of argillic and advanced argillic alteration is common in South Urn Monqul area, North Eastern Desert. Egypt. The alteration is exclusively hosted by NE-SW and NW-SE sheared volcanic rocks (dacite and rhyodacite porphyry) as well as intrusions (sub-porphyritic biotite granite and granite porphyry). Argillic alteration is dominated by clay minerals that are usually associated with phyllic alteration. Advanced argillic alteration, on the other hand, comprises quartz, alunite. clay minerals, pyrophyllite and specularite. Mineralization linked to advanced argillic alteration is represented by gold with the high sulphidation minerals enargite, chalcocite and covellite. The high sulphur content of acid sulfate alteration is further emphasized by the common presence of barite veins in the examined area.
It is envisaged that volatiles rich in SO2 degassed from the near surface intrusions, which were unable to re-equilibrate with the country rocks along their relatively short path of ascent. As a result, the S02 produced sulphuric acid in conjunction with meteoric water. The interaction of the sulphuric acid solution with the wall rock resulted in the advanced argillic alteration.
The recognition of such alteration in the Eastern Desert is of prime importance where it can be used, as a shallow level indicator of a possible deeper porphyry system, in any exploration program
Abdel-Azim M. Negm, Ehab M. Wafaie and Abdul-Aziz A. Al-Othman
This study presents the results of experiments on the effect of roughness height on the performance of hydraulic jump type stilling basins. The length of jump is taken as the main criterion for the length of the stilling basins. The experimental work is conducted on a large laboratory flume to minimize side wall effects. Non-dimensional empirical formulae are developed to compute the length of the hydraulic jump in terms of the roughness height ratio and the approaching flow Froude number. Design curves and equations are also provided for field applications.
Ismail A. EL-Shahat
A simple state decentralized self-tuning is designed for suboptimal control of multivariable systems. The suboptimal decentralized self-tuner is calculated by using a cost function with degree beta and the recursive least squares identification method. The suboptimal decentralized adaptive control law for the large-scale system is obtained from the adaptive control laws of the subsystems. The algorithm is extremely easy to program on a computer
M.S. Omar, B.M. Omar and F.A. Mahmood
The temperature dependence of the optical properties was investigated for the chalcopyrite ternary semiconducting compound ZnGeP2. The energy gaps were found to be pseudo direct allowed transitions with gaps of 1.87 eV and 1.94 eV for the two investigated samples . The temperature coefficient of the energy gap was also determined in the temperature range (300-400) K and are found to be -5.18 x 10-4 eV/K and -4.99 x 10-4 eV/K for the above mentioned samples.
H.A. Abulfatih
The 1-year old field is characterized by having 6 species, which belong to two life forms including therophytes and hemicryptophytes, low plant cover (15%), sandy soil with less humus and lower field capacity (20.2%).
The 4-year old field is characterized by having 32 species of a more diverse life forms, including therophytes, hemícryptophyes, chamaephytes and phanerophytes; moderate plant cover (55%); sandy-loam soil with more humus and higher field capacity (33.3%).
In both fields most plants started growing in late April, after the beginning of the winter rainfall. Importance value index, measured in late July 1997, at the time of maximum productivity, showed that Cornulaca sp., Lamarckia aurea, Bromus arvensis, Fagonia indica, Zygophyllum simplex were the most prominent species in the 1-year old field. On the other hand, Bromus arvensis, Comulaca sp., Francoeria crispa, Plantago afra, Osteospermum vaillantii were the most prominent species in the 4-year old field. Yet, more perennial species were found in the 4-year old field.
For six months, during the relatively dry period of the year, between September and February, not a single plant was seen over the ground surface in the 1-year old field. On the contrary, during the same dry period, in the 4-year old field, many perennial plants were found carrying little leaves. These plants included the ones that behaved as hemicryptophytes, chamaephytes and phanerophytes. They Francoeria cripsa, Ochradenus baccatus, Osteospermum vaillantii, Pulicaria sp.. Solanum nigrum, Solanum schamperi, Solanum sepicula, Solanum villosum, and Ziziphus spina-christi.
In the semitropical arid areas as in Sana'a plant species are able to use various tactics to cope with the droughtiness. From the life form viewpoint, plants during the prolonged drought period either die (Therophytes), save water by losing their leaves while keeping their roots and renewal buds (Hemicryptophytes), or extending their roots to the subsoil moisture as in the cases of the dwarf perennial shrubs (Chamaephytes) and the trees Phanerophytes).
K.F. Elkhalifa and S.M. Mahmoud
Guddeim (Grewia tenax Forssk.) is one of the important trees native to Sudan. Despite its economic importance in agroforestry, medicine, and nutrition, little or no information is available on its propagation. The present study is an attempt to report on its production by seedlings and stem cuttings in the nursery.
For seedling production, three soil media and three watering intervals were tried.
Above ground parameters (diameter at collar, shoot height number of leaves plant and shoot dry weight) and below ground parameters (root length and root dry weight) were measured. The condition for growth was found to be the use of pure river sill soil with daily irrigation for the first six walause six weeks as initial establishment, and watering every four days thereafter under partial shade.
For stem cutting propagation, Indole butyric acid (IBA) and Naphthalene acetic acid (NAA) were used. However, neither of the two hormones did improve rooting percentage, compared to the control.
M.A. Elhaak
Callus from the desert plant Gymnocarpos decandrum was developed and recultured in a medium supplemented with Abscisic acid (ABA). Growth, osmotic potential, water content and some osmoregulatory metabolites were analyzed. Addition of ABA in the callus medium enhanced a callus growth without counteracting other growth regulators in the medium. Added ABA increased callus water uptake, important in resing imposed stresses. The acid also enhanced osmoregulation, regardless of callus water content, by accumulation of some metabolites and not by nutrient elements. The latter were exhausted by increased callus growth activity. Apart of this, there was an increase in the amino acids which reversed ABA inhibitory effect and a decrease in those which enhanced its effect; even some of them could not be detected with time of ABA application. The accumulation of proline was a function of ABA and not of water content, while the reverse was true for quaternary ammonium compounds (QAC).
Muna Z. Qadoumi, Sami K. Abdel-Hafez and Shaden A. Kamhawi
The morphological characteristics of the larval stages of four laboratory-reared PhLebotomus species. collected from Jordan, were studied. The length, shape and distribution of body hairs of the fourth larval instar (L4) of P. syriacus, P. mascitti, P. kazeruni and P. tobbi formed a pattern that can distinguish one species from another P. tobbi possessed a single pair of caudal bristles. Distinctive chaetotactic features of L4 instars of the described four species were compared to those of P. Langeroni.
Khaled A. S. AL-Rasheid
Sediment samples were collected at low tide from various localities of Jubail Marine Wildlife Sanctuary in the Arabian Gulf during 1996-1997 for the study of the marine interstitial ciliate fauna of the Sanctuary. Nineteen species belonging to the order Heterotrich Ida were identified, eleven of these represent new records for the fauna of the Arabian Gulf and Saudi Arabia: Blepharisma seculum, B. hyalinum, Gruberia beninensis, Pseudo Blepharisma tenue, Spirostomum teres, Metopus contortus, Condylostoma acuta, C. longicaudata, C. tardum, Linostoma vorticella, and Stentor niger. The distribution and main taxonomic characters of each species were compared to those in similar habitats worldwide.