Vol. 9 Issue 3
Mohammed A. Shayib
Andrews (1973) gave a general method for the approximation of tail areas in statistical problems. Gross and Hosmer (1978) extended the methodology of Andrews. Awad and Shayib (1986) contributed a wider generalization for approximating tail areas of distributions that were not addressed before. These works led to several formulas for approximating the tail area of a distribution. This article applies lour approximating formulas to the t, chi-square and F distributions. Numerical values of relative errors are given to compare the merits of the formulas. The results show that the methods considered here overestimate the tail areas. Moreover, the formula proposed by Awad and Shayib is the simplest to USC.
Ali, S.A. and Mazhar, H.S.
The catalytic conversion of cyclohexane on a Ni-Al2O3, α-Al2O3, catalyst (31.1% of Ni by wt.) was studied using a flow technique. The catalytic activity was measured in the temperature range 400 to 480°C at a space velocity of 9.4-17.8 X10-2 min - I under normal pressure (1 atm). The gaseous and liquid products of the conversion reaction were analysed chromatographically. The gaseous products were hydrogen and methane, and the liquid products were benzene and cyclohexene together with unreacted cyclohexane . The kinetics of the gaseous products and of cyclohexane revealed a zero-order reaction , but that of cyclohexene and benzene did not. The apparent activation energy was found to be 23 .76 ± 0.2 kcal mol-1 independent of the space velocity .
The activity and selectivity were discussed referring to the Ni-AI2O3, solid catalyst prepared before (Ni-A).
Maarib A. Khalid
The influence of the electron-phonon interaction on the De Haas-van Alphen effect amplitudes is calculated using a theory of Engelsberg and Simpson (1970). Calculations are presented on Hg using self-energies calculated from the α^2(v) F(v) spectrum found from superconducting tunnelling data. The largest changes are found for the first harmonic: 30% in amplitude for the orbit at 15 tesla. The 10th harmonic shows large deviation also 2%.
S.A. Al-Suhaibani, A.S. Babeir, John Kilgour and Simon Blackmore
Dates are one of the most important crops in Saudi Arabia. Many of the cultural operations, and particularly harvesting, require the man to climb the tree and work at a considerable height from the ground. This is a dangerous operation further compounded by a severe labour shortage.
The overall size, reach, ground clearance and power required by a machine was decided after a survey carried out in Saudi Arabia in 1985.
A prototype machine has now been manufactured and completed a set of field trials in 1989. It is slower to move and position itself at the tree but the harvesting can be carried out more conveniently and faster than traditional (hand) method. Recommendations stated that the machine can be simplified and made to work more conveniently and faster as well as the need for economic evaluation.
Ahmed A. Al-Noaim, Adel A. El-Gazzar, Trevor G. Rumney and Younis S. Al-Koraiem
The chemical composition and seed germination of range plants located in the Eastern Province of the Saudi Arabia together with the chemical analysis of soil associated with them was evaluated in this study. The distribution of the important range plants was found in three main locations in the Eastern Province. These locations were Naeeryah, Wadi Al-Mayah and Hofuf-Salwa Road.
The results of the study indicated that seven species are potentially useful grazing plants and hence they could be domesticated; of those, Plantago ovata, Prosopis [arcla and Hammada elegans, had relatively high protein content ranging from 11.3 to 12.6% at maturity, while the other four, Panicum turgidum, Pennisetum divisum, Stipagrostis plumosa and Rhanterium epapposum had relatively low protein content, ranging from 6.5 to 7.4% at maturity. All species had a wide distribution and good palatability. Chemical analyses of plants included proximate analysis and determination of major and minor elements. Except for phosphorus, all of the selected seven species contained adequate amounts of the minerals required for animal nutrition, when sampled at maturity . Soil was analysed for pH, electrical conductivity and available cations. All samples had pH ranging from 7.95 to 8.68, while the electrical conductivity ranged between 0.26 to 1.92 mS/cm. Available Cu and Mn in the soil were found to be adequate, whereas available Fe was deficient and available Zn was borderline, according to the criteria of Lindsay and Norvell (1978).
Results of seed germination experiments carried out on five of the seven selected species showed a low percentage of germination, ranging from 0 to 40% . However, when the seeds were stored for a period of about 10 months, the germination percentage increased to about 65 to 90%. Representative photographs of seven of the studied species are shown.
Fawzi M. Karim
Recent extensive floristic collections from U.A.E. especially the Masafi- Dibba Zone, in the northeast of the country near the straits of Hormuz, revealed the presence of 7 new taxa of the Flora of U.A.E. These are: Senecio flavus (Asteraceae), Trigonella stellata (Fabaceae), Teucrium mascatense (Lamiaceae), Linum corymbulosum (Linaceae), Papaver glaucum (Papaveraceae), Oligomeris subulata (Resedaceae), Ranunculus muricatus (Ranunculaceae).
Mohammed Ali Zidan
The interactive effect of salinity and some vitamins; thiamine, nicotinic acid and pyridoxine on growth and some metabolic changes of wheat (Triticum aestivum L.) were studied. Salinity induced a considerable reduction in growth, pigment contents, carbohydrates and proteins in wheat plants. However, proline contents of the main plant organs were increased progressively with the increase of salinity level.
When these salt stressed plants were sprayed with thiamine, nicotinic acid or pyridoxine the growth, pigments and accumulation of carbohydrates and proteins were considerably increased. However, proline contents were decreased as compared with the corresponding treatments with NaCl. These results may lead to the conclusion that, each of the three vitamins used can alleviate the adverse effects of salt stress.
A.A. Khodair, A.S. Ramadani and A.M. Aggab
All soil samples were inhabited by alkalophilic, including alkalotolerant, bacteria in counts ranging from 3.7 to 37.2 (x 10^4)/g oven-dried soil. The density of alkalophilic fungi was significantly lower and their occurrence was restricted to only three sites out of four. The total alkalophilic bacteria of samples in vicinity of sea water were higher than in other inland samples. In presence of low organic matter, salinity appeared of more drastic effect on alkalophilic fungal population than bacteria. Increased content of soil organic matter appeared as a factor, beside others, which plays a probably role in minimizing the inhibitory effect of high salinity.
The genus Bacillus predominated in frequency, Gram negative rods were of moderate occurrence, while Gram positive micrococci and Gram positive asporogenous rods were of low frequency. Only 3.4 to 33.3% of Bacillus isolates together with all Gram positive asporogenous rods were obligate alkaliphiles; the remaining isolates were either facultative or alkaline-tolerant.
Eight fungal genera could be identified as alkalophilic fungi. Aspergillus was the highest in occurrence but Fusarium was the highest in density at only one site.
S.A. Mohamed
Movement and distribution of The Greater Flamingo, Phoenicopterus ruber was studied for two years around the shores of Bahrain. Thirty-one sites were monitored bimonthly, and absolute numbers of adult and immature birds were counted. The maximum number of birds was recorded in the month of December for two consecutive years. The study shows that the eastern sheltered shores of Bahrain are the main wintering areas for flamingos where they can be seen during most of the year with the exception of the months of June and July. The study also shows that flamingos in Bahrain are mainly wintering but some visit the shores as passage migrants during Autumn and late Spring.
Hussein S. Hussein, Nasser A. Al-Asgah, Mohammed S. Al-Khalifa and Fathi M. Diab
The blood parasites of indigenous camels, sheep, goats and cattle were investigated in several localities in Saudi Arabia that are well isolated from any possible mixing with imported animals. The present study is the first detailed investigation on blood parasites infecting indigenous livestock in Saudi Arabia. Trypanosoma evansi and an Eperythrozoon sp. were detected in camels. Sheep and goat were infected with Theileria ovis, Theileria hirei and with Eperythrozoon ovis and cattle with Eperythrozoon wenyoni, Theileria annulata and with a nonpathogenic Theileria sp. Apart from T. evansi and T. annulata, all parasite species are reported for the first time from Saudi Arabia. The detection of an Eperythrozoon sp. form the camel is the first from this host. Theileria ovis and E. ovis were reported from all provinces examined, while T. hirei was confined to eastern and northern parts of the Kingdom. Eperythrozoon wenyoni was found in both of Hofuf and Gizan, but T. annulata occurred in Hofuf only and the nonpathogenic Theileria sp. in Gizan only. Areas of highest camel trypanosomiasis prevalence were heavily ingested with tabanid flies whose role in the transmission os the disease was discussed. The pathological effects of the reported blood parasites on their hosts were discussed together with the role of ixodid ticks in the transmission of the Theileria species.