Showing papers by "Cairo University published in 1976"

Experimental Investigation of Flow Over Side Weirs

Abstract: Observations at numerous cross sections in a side weir channel showed that the total energy of flow decreases substantially along the channel, contrary to the assumption that has frequently been made. The decrease in total energy occurs because the longitudinal component of velocity of the spill flow is greater than the longitudinal velocity of the flow remaining in the channel. A satisfactory flow equation is derived from momentum principles and this is further developed into a computer technique for calculating flow profiles and spill discharges for side weirs.

Reactions with the Arylhydrazones of α-Cyanoketones: The Structure of 2-Arylhydrazono-3-ketimino-nitriles

Abstract: Analysis of the IR., UV., and polarographic data of a variety of 2-arylhydrazono-3-ketimino-nitriles indicated that these derivatives exist mainly in the intramolecularly chelated hydrazone structure 1. Compounds 1 reacted with hydrazine hydrate to yield the corresponding 5-amino-4-arylazopyrazoles (3). Compounds 3a reacted with acetylacetone, ethyl acetoacetate, and diethyl malonate to yield the pyrazolo[1, 5-a]pyrimidine derivatives 4, 5, and 7 respectively. Compound 3a also reacted with benzoylisothiocyanate to yield the pyrazolyl thiourea derivative 8.

On the Dynamics of Linear Non-Conservative Systems

Abstract: A number of results are presented, relating to the matrix equation Aq + Bq + Cq = Q(t) . It is not assumed that the system matrices A, B and C possess any of the familiar properties (of symmetry, skew symmetry or positive definiteness). These results relate to free motion in which Q(t) = 0, to forced harmonic motion in which Q(t) = ϕ e iωt and to transient vibration in which Q(t) is an arbitrary function of time.

Free and forced oscillation of a vertical tube containing a flowing fluid

Abstract: A flexible vertical tube, clamped at its upper end and carrying a nozzle at its free lower end, can become unstable when a liquid flows down it. The system is a convenient one for the study of passage through an instability boundary as it is amenable to theoretical and experimental investigation of both free and forced oscillation. This paper presents the results of a theoretical and experimental study of the motions with special reference to the instability boundary.

Differential Association Between Chronic Cannabis Use and Brain Function Deficits

Abstract: To summarize, 12 objective tests that generated 16 test variables were administered to 850 male regular cannabis users and 839 nonusers. The tests were designed to assess various modalities, including speed of psychomotor performance, distance estimation, time estimation, immediate memory, and visuomotor coordination. Most of the test variables differentiated significantly between consumers and controls. At the same time, a significant second-order interaction emerged in most cases. This interaction meant that, under certain conditions that relate to the two dimensions "literacy-illiteracy" and/or "urbanism-ruralism," the superiority of controls over cannabis users became impressive, whereas under other conditions it almost disappeared. To account for this complex pattern of results, a working hypothesis was presented to the effect that "other conditions being equal, the lower the nondrug level of proficiency on tests of cognitive and psychomotor performance the smaller the size of function deficit associated with drug usage." For an empirical examination of the hypothesis, six predictions were formulated. Three predictions defined specific relationships between level of performance, on one hand, and each of three organismic variables, on the other: literacy, urbanism, and age. The remaining predictions delineated relationships to be expected between size of function deficit and the three organismic variables. All our predictions were confirmed, showing less function impairment to be contingent with cannabis usage among the illiterates, rurals, and older subjects. Level of cortical arousal was suggested as the central process associated with the three organismic variables. Because the version of our working hypothesis was formulated with reference to chronic material, the possibility of a transposition of the paradign to research on the acute effects of the drug was discussed. The suggestion was made that our working hypothesis, in either version, is capable of establishing genuine integration between reports that present conflicting results on possible function deficits contingent with cannabis consumption. Language: en

Comparing ridge resorption with various surgical techniques in immediate dentures

Abstract: The three surgical techniques of simple tooth extraction and labial plate and intraseptal alveoloplasty were compared. The results were confirmed by statistical analysis. The conclusion of this study clearly indicated that simple tooth extraction is the best surgical approach to be followed to preserve as much of the residual alveolar ridge as possible.

Momentum distributions in fragmentation reactions with relativistic heavy ions

Abstract: The momentum distribution (or angular distribution) in inelastic heavy ion reactions is calculated by using a two-step model (“abrasion” and “ablation”). First, all nucleons in the volume element where projectile and target overlap spatially during the collision are sheared away. The remaining prefragment (the projectile minus the sheared off nucleons) has a recoil momentum proportional to the Fermi momentum. The prefragment is left in an excited state and emits nucleons, the recoil momentum given to the final fragment is proportional to the nuclear temperature. This two-step model reproduces the overall trend and the isotopic dependence for the widths of the experimental momentum distributions. Contrary to previous theoretical studies we find that surface and friction phenomena lead to an anisotropy: The momentum distributions in transverse direction are always broader than in the longitudinal direction by about 5 to 10%.

Analysis of the discharge development of a positive rod-plane gap in air

Abstract: An improved method is suggested for calculating and correlating the burst pulse and streamer onset voltages of a positive rod-plane gap in air. The computed results indicate that the positive corona in rod-plane gaps always starts with burst pulses in agreement with experiment. The conditions of burst pulse-streamer and burst pulse-glow transitions are also discussed. It is found -for the first time-that the photoelectron distribution within the ionization zone, which depends upon the gap geometry, plays an important role in deciding the discharge development from burst pulses.

Treatment contrasts in paired comparisons: Basic procedures with application to factorials

Abstract: : A simple procedure for consideration of specified treatment contrasts or sets of contrasts in a paired comparisons experiment is developed. General likelihood estimation and likelihood ratio tests are given. Specified treatment comparisons as appropriate in a particular experiment may be made. The procedure may be used for consideration of factor effects and interactions when the treatments in paired comparisons are factorial treatment combinations. An example is given of a taste preference experiment on coffee with factors, brew strength, roast color and brand, each at two levels. Results are summarized in an analysis of chi-square table very analogous to the typical analysis of variance summary.

A Note on the Estimation of Azotobacter Densities by Membrane Filter Technique

Abstract: 1 Membrane filter technique is recommended for routine analysis of water and soil particularly those with low Azotobacter density. 2 Tests of four brands of membrane filters used for enumerating different groups of bacteria showed that highest Azotobacter counts were obtained with Millipore and Sartorius membranes. 3 Boiling of the membranes for 5 min in distilled water leads to the removal of possible substances toxic to the development of Axotobacter cells which was demonstrated by the increase of the recovered colonies, and to equal estimates obtained with the various brands.

Arid and semi-arid lands: Problems and prospects

Abstract: A survey of the world's deserts and processes of desertification identifies those that are strictly due to physical factors and those that are anthropogenic. Areas of potential useful study are identified: improved climate, climatic research and monitoring, improvement of arid zone cultivars, improved techniques of decision-making about land use. Warnings are given of the dangers of over-intensification of agricultural systems and of increasing population density in arid zones. Research areas suitable for international co-operation are outlined.

A cooperative study of sarcoidosis in Asia and Africa: descriptive epidemiology.

Abstract: An eight-nation cooperative epidemiological study revealed the Asian and African features of sarcoidosis. Almost every country reported from several to less than 30 cases, except for Japan which had already collected over 3,000 cases. Not a single case was found in the mass x-ray surveys conducted by several countries on a large scale (Tables 1 and 2). Although the number of the cases included in this study were small, this information is the first of this kind for Asia and Africa.

Calculated Channel Characteristics of a Braided Coaxial Cable in a Mine Tunnel

Abstract: The braided coaxial cable is studied as a communication scheme in a mine tunnel. A simplified rectangular waveguide model is adopted for the tunnel, and the shield of the cable is assumed to behave as a single inductive transfer impedance. Specific results on the attenuation of the monofilar and bifilar (or coaxial) modes of propagation, taking into account the possible existence of a thin lossy film on the cable, are presented. In order to estimate the maximum possible range of communication, we consider the coupling factors of these modes to transmitting and receiving dipoles inside the tunnel, and we present results on these factors for various cable parameters and over a wide range of frequencies.

On the Equations Governing the Free and Forced Vibrations of a General Non-Conservative System

Abstract: An expression is derived for the steady forced response of a system governed by the equationin which A, B and C are real but not symmetric. The theory is effectively an adaptation and exploration o...

A comparative study of antidepressants in the treatment of depressive states.

Abstract: The effect of six antidepressants has been investigated in six groups of twenty patients suffering from depressive states. The over-all response of the six groups, as well as the response of the individual target symptoms of depression according to the Hamilton Rating Scale are reported.

The influence of wife's education on fertility in rural Egypt.

Abstract: Data were collected from a sample of 1234 married women of childbearing age 14-49 years in rural Egypt in order to examine the effects of the wifes education on fertility and family planning. The focus was on such variables as frequency of pregnancy pregnancy loss live births and childhood mortality; attitude toward fertility; and the variation and extent of contraceptive use. The analysis revealed that the wifes education is a very important factor. Although education cannot be separated from all the other socioeconomic factors it can be primarily used as an indicator. On the basis of the analysis the following conclusions were reached: 1) more education leads to more approval of the use of contraceptives more favorable attitudes toward small family size and spacing of births and more knowledge of contraceptives; 2) a higher level of education for the wife is associated with lower rates of pregnancy loss and childhood mortality; 3) a positive association exists between pregnancy loss infant mortality and number of live-born children; 4) favorable attitudes toward family size and more knowledge and approval of contraceptives lead to their increased use; and 5) contraceptive use leads to the control of the number of live-born children.

Influence of loading behavior on the post buckling of circular rings

Abstract: (5) Finally, the loading energy of the hydrostatic pressure, which is equal to the product of the external pressure and the difference of the area of the buckled and unbuckled configuration, can be written as Trc = irb + P§(w— wv + vw) dtp (6) Considering the auxiliary condition (due to e = 0) 1 l r ? — (w — v) + ——— [ (w — i ) ) J H ( w + y ) ] = 0 (7) r 2r in eliminating w from Eq. (3), the following components of the potential functional JF= E TT= W2+ W3 + ... are obtained

Level Structure and Transition Probabilities in 165Tm and 167Tm

Abstract: Transitions in 165Tm and 167Tm have been studied by means of the (p,nγ) and (p,2nγ) reactions. Singles gamma-ray spectra, gamma-gamma coincidences and conversion electron spectra have been recorded. The level schemes of both isotopes have partly been verified and new members of the 1/2-[541] band have been found in 167Tm. The halflives of three levels in the ground state bands have been measured using an electron-electron coincidence spectrometer: T1/2 = 322 ± 20 ps for the I = 7/2 level in 165Tm, T1/2 = 343 ± 15 ps for the I = 7/2 level in 167Tm and T1/2 = 66 ± 7 ps for the I = 5/2 level in 167Tm. The electric and magnetic moments have been compared for the odd thulium isotopes. It was also shown that the quadrupole deformation 2 is constant and that the systematics of the single particle states in these isotopes only may be explained by variations of the hexadecapole deformation, 4 of the nuclear shape.

Line strengths and lifetimes for Kr II

Abstract: Relative line strengths have been calculated for transitions between states of the 4p 4 5p and 4p 4 5s configurations in Kr II. The wavefunctions are obtained in intermediate coupling, including an effective correction for configuration interaction. Absolute values for the line strengths are determined using the coulomb approximation. Lifetimes for the upper 4p 4 5p levels are given together with available experimental results for comparison.

Reactions with Thiazolo[3,2‐b]‐s‐triazol‐3(2H)‐ones

Abstract: 5-Aryl-3-carboxymethylthio-1,2,4-triazoles 2 are cyclised to 6-arylthiazolo[3,2-b]-s-triazol-3(2H)-ones 3. This structural assignment has been based on IR and NMR spectra. 2-Arylmethylene-6-arylthiazolo[3,2-b]-s-triazol-3(2H)-ones 7 were prepared by several methods. Compounds 3 coupled with diazotised anilines to give 2,3-dihydro-6-arylthiazolo[3,2-b]-s-triazole-2,3-dione 2-arylhydrazones 8. The action of amines on 3a opens the thiazolone ring with the formation of substituted (5-phenyltriazol-3-ylthio)-acetamides 9. Reaktionen mit Thiazolo [3,2-b]s-triazol-3(2H)-onen 5-Aryl-3-carboxymethylmercapto-1,2,4-triazole 2 werden zu 6-Arylthiazolo[3,2-b]s-triazol-3(2H)-onen 3 cyclisiert. Die Strukturzuordnung wurde anhand von IR- und NMR-Spektren getroffen. 2-Arylmethylen-6-aryl-thiazolo[3,2-b]s-triazol-3(2H)-one 7 wurden nach verschiedenen Methoden erhalten. Die Verbindungen 3 kuppelten mit diazotierten Anilinen zu den 2-Arylhydrazono-6-aryl-3-oxo-2,3-dihydro-thiazolo[3,2-b]s-triazolen 8. Unter der Einwirkung von Aminen auf 3a wird der Thiazolonring unter Bildung der substituierten 5-Phenyltriazolyl-(3)-mercapto-acetamide 9 geoffnet.