Showing papers by "American University in Cairo published in 1974"

public and private politics: women in the Middle Eastern world1

Abstract: The main questions examined in this paper are: (1) What is the notion of power as this has been used by ethnographers writing about nomadic and sedentary societies of the Middle East? (2) Given this notion of power, what are the images of women and power in the domestic and public domains? (3) What are the epistemological consequences to ethnography if we re-think our notions of power and recognize its special features as a particular kind of social relation—reciprocity of influence—rather than as an embodied quality institutionalized in kinds of social structures?

Ferrous and ferric ions in synthetic α-quartz and natural amethyst

Abstract: The generation and the removal of the various optical absorption bands in natural amethyst and in synthetic a-quartz doped with either Fe'* or Fe\"* ions has been surveyed. Fositive rhombohedral growth regions of synthetic a-qvattz containing Fe'* ion proved to be related to the generation of the amethyst color upon treatment with ionizing radiation. It is believed that the interstitial Fe'* ions in voids perpendicular to positive rhombohedral faces furnish charge compensation for substitutional Fe\"* ion. This combination is the precursor of several color centers responsible for the production of the amethyst color.

A note on the relationship between english proficiency, years of language study and medium of instruction

Abstract: The purpose of this investigation was to examine the relationship between measured English-language proficiency, years of English-language study and the use of English as a medium of instruction for samples of Arabic-speaking Egyptian and Lebanese university students. The results of multivariate regression analyses indicated no systematic relationship between years of EFL study and English proficiency. A better overall predictor of proficiency was whether the students had received any instruction via a foreign language. We emphasize the need to begin a more systematic search for factors related to increases in English-language proficiency at various stages of study under diverse circumstances.

Reactions of α‐Arylhydrazono‐β‐oxo‐β‐phenyl‐propionitriles

Abstract: ω-Cyanoacetophenone was coupled with a variety of aromatic diazonium chlorides to give the corresponding arylazo derivatives 1 a–g. Analysis of the IR and UV spectra of these compounds indicated that they exist mainly as the corresponding arylhydrazones. Compounds 1 a–d, f, g reacted with diazomethane to yield the N-methyl-arylhydrazones 2 a–f. 3-Amino-4-arylazo-5-phenylpyrazoles 5 a–g and 4-arylazo-5-imino-1,3-diphenyl-2-pyrazolines 6 a–g were obtained by the interaction of 1 a–g with hydrazine hydrate and with phenylhydrazine, respectively.

Studies on Nonmetals During Irradiation: V, Growth and Decay of Color Centers in Barium Aluminoborate Glasses Containing Cerium

Abstract: The radiation-induced absorption of a group of barium aluminoborate glasses was studied in a new facility for measuring optical absorption during irradiation with γ-rays. The results demonstrate that this technique provides significant new information on the kinetics of the radiation-induced coloring of glasses and suggest that most previous measurements are, at best, suspect. Barium aluminoborate glasses, both with and without Ce, were prepared under normal and reducing conditions. The coloring during irradiation and the decay after irradiation can be characterized by the absorption at 3.0 e V and at 2.25 or 1.90 e V. The Ce-free base glass continued to color as long as irradiated and, at a given dose, the absorption was at least 2 or 3 times that of the other glasses. The totally reduced 1% Ce glass colored to a constant level in the uv, but in the visible the coloring increased to a maximum and then decreased to a constant value. The partially reduced 1% Ce glass also colored to a constant value in the uv, but in the visible the original absorption decreased slightly. All the coloring curves recorded during irradiation are described accurately by expressions that include one or more increasing saturating exponential terms and may contain one linear or one decreasing saturating exponential term. After irradiation the coloring curves decrease and can be resolved accurately into one or more decreasing exponential components. Futhermore, all the observed coloring-curve features were derived from relatively simple kinetics.

Mössbauer and X-ray photoelectron spectroscopic studies of heat-treated calcium borate glasses containing iron

Abstract: 57Fe Mossbauer and X-ray photoelectron spectroscopic studies have been carried out on a number of iron-containing calcium borate glasses which show large changes in d.c. conductivity upon annealing. The Mossbauer spectra of the unannealed glass samples are compatible with the presence of predominantly ferric iron in a six-co-ordinate oxygen environment. Upon annealing a partial ordering of the glassy phase is found as indicated by a reduction in the linewidth of the Mossbauer resonances. Longer annealing times lead to the precipitation ofα-Fe2O3 clearly identified by the gradual appearance of a six-line magnetically split pattern in the Mossbauer spectra. These changes are qualitatively correlated with changes in d.c. conductivity of the samples. The binding energies and full width at half maxima of representative core levels of each element present show a remarkable consistency for all samples. Moreover the 2p spectra of iron incorporated in the glassy phase are essentially similar to that of the precipitated Fe2O3.

ESR and Structural Studies on Pseudo-Alexandrite

Abstract: Structural analysis using x-ray, mass spectroscopy and ESR measurements were made on “Alexandrite” stones obtained from markets in Egypt, Germany and Sweden. The results show that all the samples studied are not synthetic Alexandrite but are synthetic crystals of α-Al2O3 doped with varying concentrations of vanadium, chromium and iron. The crystals show similar optical properties to Alexandrite crystals (the chromium bearing chrysoberyl, BeAl2O4:Cr) and are therefore termed “pseudo-Alexandrite.”

Role of Iron and Electrical Conductivity in Iron Calcium Phosphate Glasses

Abstract: Mossbauer spectroscopy, X-ray diffraction and magnetic susceptibility techniques were used to study the role of iron in calcium phosphate glasses before and after heat treatment. Factors affecting the electrical conductivity of these glasses included the total iron concentration, ferrous-ferric ratio, devitrification by heat treatment, and the type of local order in the glass. An exponential decrease in log ρ was observed with increasing total iron concentration from about 8 to 17 wt. % Fe2O3. The range at which there is a change in slope of the exponential (about 11–13 wt. % Fe203) is characterized by the presence of a new compound (FePO4) in the heat treated samples, as confirmed by X-ray diffraction studies. These samples, heated for 88 hours at 750°C, showed a minimum resistivity. The foregoing observations support the postulate that local order in the glasses of this series is similar to that in corresponding crystals separated on devitrification of these glasses by heat treatment. The appearance or disappearance of these crystals (eg. FePO4) at certain compositions was found to coincide with changes in physical properties such as conductivity.

Structural Changes in Borate Glasses

Abstract: A series of potassium borate glasses (100-x) B2O3.K2O) was prepared from analytical reagent chemicals and the glass samples were analysed for the determination of potassium and boron concentrations. Many physical and chemical properties of these glasses were studied and the property-composition curves are presented. Four structural changes are observed in the property-composition curves at about 10, 20 28 and 32 mol% K2O. Detailed computer calculations for the number of BO4 groups, bridging oxygens, and non-bridging oxygens as a function of the alkali oxide concentration are also presented. These calculations are based on recently published hypotheses for the structure of alkali borate glasses. Comparison between the experimental results and the calculations indicates the following: a) The change at about 10 mol% K2O is due to the appearance of very small concentrations of non-bridging oxygens, while the change at about 20 mol% K2O is due mainly to the large increase in the non-bridging oxygens concentration at that composition. b) The change at about 28 mol % K2O is due to a maximum in the number of bridging oxygens. c) The change at about 32 mol% K20 is due to a maximum in the fraction of the four-fold coordinated borons. Some properties are determined either by the number of BO4 groups or by the number of non-bridging oxygens, others by the combined effect of these configurations. The possibility of extending the calculations to other borate system is indicated.

The functional development of language in a child of two-and-a-half years.

Abstract: A functional model of child language development put forth by Halliday (forthcoming) is applied to the speech of a 30 month old child. The functional system postulated for a child just beginning to...

Electrical Switching in Calcium Phosphate Glasses Containing Iron

Abstract: Electrical switching was studied in a series of calcium phosphate glasses containing iron. The samples were prepared by melting and evaporating of the glasses. The switching phenomena was studied using a.c. and d.c. voltages. The samples showed switching, from a high resistance state (off-state ≥ 10 M Ω) to a low resistance state (onstate ≤ 1 KΩ) at certain threshold voltages. The switching was invariably of the memory type and a high current pulse was required to switch the samples to the off-state. In most cases, no negative resistance was observed. The threshold switching voltage decreased with higher iron content and with decreasing thickness of the samples. The most significant parameter appeared to be the temperature; a marked decrease in threshold voltage was observed with increasing temperature of the sample.

Some Properties of Photochromic Borosilicate Glass

Abstract: Borosilicate glasses containing silver were made photochromic by heating the samples in air at 750° for four hours. The heat treatment resulted in the shift of the absorption edge by about 0.5 ev. The photochromic glass could be darkened by exposing it to wavelengths 400 nm and shorter. The darkening of the glass is shown to be related to the optical absorption curve, suggesting its relation to the excitation of electrons to the “conduction band”.

ESR and Optical Studies of Induced Centres in Binary Silver and Alkali Borate Glasses

Abstract: A series of binary borate glasses containing up to 35 mol% Ag20 was X-irradiated and the induced centres were studied by means of ESR and optical absorption spectroscopy. The results showed that the Ag+ traps an electron or a hole to form AgO or Ag++ respectively. The induced ESR spectra of these centres consisted of two hyper fine Ag° lines (g = 2.20 and g = 1.83) and an axially symmetric line for Ag++ (g⊥ = 2.04 and g″ = 2.31). This is in line with what has previously been reported for low silver content glasses.