Showing papers by "Cairo University published in 1992"

Nonlinear joint angle control for artificially stimulated muscle

Abstract: Designs of both open- and closed-loop controllers of electrically stimulated muscle that explicitly depend on a nonlinear mathematical model of muscle input-output properties are presented and evaluated. The muscle model consists of three factors: a muscle activation dynamics factor, an angle-torque relationship factor, and an angular velocity torque relationship factor. These factors are multiplied to relate output torque to input simulation and joint angle. An experimental method for the determination of the parameters of this model was designed, implemented, and evaluated. An open-loop nonlinear compensator, based upon this model, was tested in an animal model. Its performance in the control of joint angle in the presence of a known load was compared with a PID (proportional-integral-derivative) controller, and with a combination of the PID controller and the nonlinear compensator. The results are presented. >

Grading of hepatic schistosomiasis by the use of ultrasonography.

Abstract: Forty-three subjects with pure hepatic schistosomiasis having ultrasonographic assessment of periportal fibrosis were grouped according to the thickness of their portal tracts: grade I = 3-5 mm, grade II = greater than 5-7 mm, and grade III = greater than 7 mm. A history of hematemesis, blood transfusion, sclerotherapy, and lower limb edema correlated with the ultrasonographic grade of periportal fibrosis. With increasing grade, the average liver size was smaller and the average spleen size was larger, as determined by physical examination and by ultrasonography. Abnormalities in serum enzyme levels were more frequent in those with thicker portal tracts. Greater diameters of the portal and splenic veins and ultrasonographically detectable collateral blood vessels were associated with increasing thickness of portal tracts. The grade of endoscopically determined esophageal varices was highly correlated with the grade of periportal fibrosis. We concluded that this method of grading accurately reflects the hemodynamic changes and provides a good estimate of the clinical status of patients who have periportal fibrosis due to schistosomiasis mansoni. Where available, it should replace clinical grading based upon the liver and spleen size as detected by physical examination.

The Effect of Titanium on Some Physical Properties of CuFe2O4

Abstract: The mixed ferrite Cu1−xTixFe2O4 (where x = 0 to 0.7) are prepared by the ceramic method. X-ray diffraction and IR absorption spectra in the range from 200 to 1000 cm−1 are used for analysing the compositions. It is observed that samples with x ≦ 0.4 exhibit spinel phase, whereas for x > 0.4 mixed phases of spinel and zincblende may be formed. For single phase x ≦ 0.4, the theoretical lattice parameter (ath) is in good agreement with the experimental value (aexp), which is of the order of 0.833 nm. The presence of Fe2+ ion in the A-site for all samples is realized and the entrance of Ti4+ ion into the A-site just starts at x = 0.4. Some physical properties such as density, porosity, shrinkage, and conductivity at room temperature are studied. Cu1−xTixFe2O4-Mischkristalle (x = 0 bis 0,7) werden mit einer keramischen Methode hergestellt. Rontgenbeugung und IR-Absorptionsspektren im Bereich von 200 bis 1000 cm−1 werden zur Analyse der Zusammensetzung benutzt. Proben mit x ≦ 0,4 zeigen Spinellstruktur, fur x > 0,4 entstehen Mischphasen aus Spinell und Zinkblende. Im Einphasenbereich x ≦ 0,4 stimmt der theoretische Gitterparameter ath gut mit dem experimentellen Wert aexp ≈ 0,833 nm uberein. Das Auftreten von Fe2+ auf A-Platzen wird fur alle Proben gefunden, das von Ti4+ auf A-Platzen beginnt bei x = 0,4. Einige Eigenschaften, wie Dichte, Porositat, Schwund und Leitfahigkeit, werden bei Raumtemperatur untersucht.

Conservative endoscopic surgery in inverted papilloma. Preliminary report.

Abstract: Inverted papilloma is noted for recurrence and occasional association with malignancy, leading most authors to recommend lateral rhinotomy as the initial surgical approach in all cases; however, conservative surgery has been reported to be effective in selective cases. Endoscopic control was used in the surgical treatment of three cases of inverted papilloma. In all three cases, the lesions were unilateral and localized, with limited extension into the sinonasal region, and they were not associated with malignancy or recurrent (as proved by endoscopy, computed tomography, and histopathologic examination). Total removal of the mass was achieved through a conservative intranasal approach. Endoscopic follow-up for periods ranging between 12 and 39 months, with an average of 23 months, failed to identify any recurrence. These findings point to the feasibility of applying this conservative endoscopic approach for total excision of limited lesions of inverted papilloma.

Analytic formulas for the neutralino masses and the neutralino mixing matrix

Abstract: The exact formulas for the neutralino mixing matrix and their masses are derived. These formulas have been proven to be correct through comparison with the numerical solution of the system of equations containing the masses and the matrix elements, as well as approximate fomulas previously published.

The Dubai Community Psychiatric Survey: I. Prevalence and socio-demographic correlates.

Abstract: This paper describes the methods and initial sociodemographic findings of the first community psychiatric survey from an Arabian country. It was carried out on a sample of women in Dubai, one of the seven United Arab Emirates. Psychiatric status was established using the PSE-ID-CATEGO system. The overall prevalence of disorder in these women was a high 22.7% (13.7% depressive disorders; 7% anxiety states). There was little association with sociodemographic variables, except that prevalence was high in divorced, widowed and separated women, polygamously married women and single parents. The high prevalence may be related to the rapid sociocultural change in this society. Future reports will examine the influence of sociocultural change at an individual level.

Investigation of static electrification phenomenon due to transformer oil flow in electric power apparatus

Abstract: Experimental investigations of the factors affecting the generation and accumulation of static charges due to oil flow in electrical equipment are introduced and discussed. The influence of oil temperature, flow rate, and type and frequency of electrical field energization on streaming electrification of fresh transformer oil (Diala-B) has been investigated by a closed oil cycle. In addition, comparisons between the calculated and the measured values of the relative streaming currents are introduced. A spinning disc system is also used to investigate factors that cannot be easily investigated by the closed cycle, e.g. moisture content, antistatic additives, and the material of which the rotating disc is made. The experiments have been carried out for both fresh and aged oil within the temperature range of 20 to 80 degrees C using rotating discs made of various materials. The type of rotating disc material causes evident quantitative and qualitative changes in the measured current. >

Long-term effects of heavy metals in food on developmental stages of Aiolopus thalassinus (Saltatoria: Acrididae).

Abstract: Newly hatched F1 nymphs of Aiolopus thalassinus (Fabr.) were fed on food treated with various concentrations of HgCl2, CdCl2, and PbCl2 until the end of adult life. Toxicological observations were followed in the F1 generation and in the F2 generation derived from the heavy metal-loaded F1 parents.

Bio-reclamation of saline-sodic soil by Amshot grass in Northern Egypt

Abstract: The effect of Amshot grass (Echinochloa stagninum) compared to ponding and gypsum on reducing the alkalinity and salinity of highly saline sodic soil in Northern Egypt, near Manzala lake, was investigated for 2 years. In a field experiment over an area of 273 m2, 12 plots were prepared for three treatments. Each treatment had four replicates. The treatments were ponding (5–10 cm water depth), gypsum (10 tons per feddan, where 1 feddan = 4200 m2) and Amshot cultivation. Amshot reduced the exchangeable sodium percent (ESP) of the surface layer more than ponding or gypsum treatments in both years. The reduction was significant, especially after the second year. The relative ESP was 79.3, 73.3 and 67.3% of its initial value at the surface layer for ponding, gypsum and Amshot, respectively, for the first year. The corresponding values for the second year were 55.0, 47.0 and 33.6%. The reduction in exchangeable sodium was accompanied by a decrease in the sodium adsorption ratio (SAR) at the upper 45 cm layers. The relative SAR for this upper zone after 1 year compared to its initial value was in the range of 78–90 for ponding, 60–82 for gypsum and 65–78 for Amshot. The reduction was even greater for the second year and reached its maximum with Amshot (42–45%). Amshot significantly reduced the salinity of the soil compared to either ponding or gypsum, and produced higher fresh yield than clover cultivated in such soils. Therefore, Amshot could benefit both the soil and the livestock fodder in this area of Egypt.

Perceptions and attitudes

Abstract: People have always cared about the environment, though their perceptions of environmental issues and their attitudes have evolved over the centuries. In the earlier part of this century environmentalism was essentially synonymous with wildlife conservation and considered to be the domain of a prescient, and often privileged, few. Since the 1960s environmentalism has become a movement with widespread popular support and an extensive range of interests. The United Nations Conference on the Human Environment convened in Stockholm in 1972 was a turning point in the history of environmental awareness. Growing public pressure, backed by scientific findings in the late 1960s and early 1970s on the impacts of pollutants and environmental degradation, stimulated the necessary political will. The debate that took place in the early 1970s, based essentially on air and water pollution in the North, brought home the fact that environmental degradation is caused not only by industrialization but by poverty and lack of development. The environmental movement has since become concerned with all aspects of the natural environment: land, water, minerals, living organisms, life processes, the atmosphere, climate, polar ice-caps, remote ocean deeps, and even outer space.

Schistosoma haematobium infection in Egyptian schoolchildren: demonstration of both hepatic and urinary tract morbidity by ultrasonography.

Abstract: Parasitological, clinical and ultrasonographical studies were performed upon 422 schoolchildren aged 12–16 years living in a village in the Fayoum where Schistosoma haematobium, but not S. Mansoni, was transmitted. Over half of the children gave a history of receiving praziquantel therapy during the preceding 2 years. Symptoms (e.g., haematuria, burning micturition), signs (e.g., hepatomegaly, splenomegaly) and urinary findings (e.g., haematuria, proteinuria) correlated better with the presence and intensity of S. haematobium infection after correcting for this variable. Renal obstructive lesions detected by ultrasound were 2 and 3 times as common in those with moderate and heavy infections as in those with no or light infections, and urinary bladder wall lesions were far more frequent in those with moderate and heavy infections. A mild grade of periportal fibrosis, hepatomegaly and splenomegaly were present in some children in all groups. However, the prevalence of splenomegaly correlated directly with the intensity of infection; liver lesions occurred much more frequently in children with infection or a history of treated infection than in non-infected children denying recent treatment; and no child had hepatomegaly or splenomegaly in the absence of periportal fibrosis.

Reactions with cyanothioacetamide derivatives : synthesis and reactions of some pyrazolo[3,4-b]pyridine derivatives

Abstract: The ylidene derivatives of cyanothioacetamide 1a–d reacted with ethyl acetoacetate to give the pyridinethiol derivatives 2a–d. Compounds 2a–d were used as starting material for the synthesis of several heterocyclic compounds. Reactions with hydrazine hydrate, ethyl iodide, methyl chloroacetate and α-chloro ethyl acetoacetate gave the pyridine and annelated pyridine derivatives 5a–d, 6a–d, 7a, 8b–d, and 12a–d, respectively. Compounds 7a, 8b–d and 12a–d reacted with hydrazine hydrate to yield the annelated pyridines 10a–d and 15a–d, respectively.

The effect of Sammo administration on some fundamental enzymes of pentose phosphat pathway and energy metabolites of alloxanized rats

Abstract: Sammo plant which is traditionally used in Egypt for the treatment of diabetes mellitus, was administered at low and high levels (4% and 8% respectively at the expense of starch) to adult male alloxanized albino rats, to study its effect on energy metabolism. Adenosine-5-triphosphate (ATP) in the brain (B), liver (L) and kidneys (K) organs of alloxanized rats was significantly lowered compared with the negative control. On the other hand, adenosine-5-diphosphate (ADP) and adenosine-5-monophosphate (AMP) contents in the same organs were elevated markedly. In this connection myokinase activity in cytoplasmic and mitochondrial fractions of B, L and K organs was stimulated at control. Also, the activities of some fundamental enzymes of the oxidative pentose phosphate pathway i.e. glucose-6-phosphate dehydrogenase (G-6-PD) and 6-phospho-gluconate dehydrogenase (6-PGD) in cytoplasmic and mitochondrial fractions of the same organs were markedly increased. Administration of Sammo at low and high levels reduced the consumption of ATP in B, L and K organs relative to positive control. Whereas, ADP and AMP contents were relatively reduced. Also, myokinase activity in the same organs were relatively inhibited. The activity of G-6-PD and 6-PGD in cytoplasmic and mitochondrial fractions of the same organs were also decreased relative to the positive control. Die Sammo-Pflanze wird in Agypten traditionell zur Behandlung von Diabetes mellitus verwendet. Zum Studium ihres Einflusses auf den Energiestoffwechsel von erwachsenen, mannlichen, alloxanisierten Albinoratten wird sie mit niedrigem und hohem Niveau (4% bzw. 8% zu Lasten von Starke) verabreicht. Verglichen mit der Negativ-Kontrolle werden Adenosin-5-triphosphat (ATP) in Gehirn (G), Leber (L) und Nieren (N) von alloxanisierten Ratten signifikant erniedrigt. Andererseits werden die Adenosin-5-diphosphat (ADP)- und Adenosin-4-monophosphat(AMP)-Gehalte in denselben Organen deutlich erhoht. Gleichzeitig wird die Myokinase-Aktivitat in den Cytoplasma- und Mitochondrien-Fraktionen von G, L und N bei der Kontrolle stimuliert. Weiterhin werden die Aktivitaten einiger wesentlicher Enzyme des oxydativen Pentosephosphatweges, z. B. Glucose-6-phosphat-Dehydrogenase (G-6-PD) und 6-Phosphogluconat-Dehydrogenase (6-PGD), in den Cytoplasma- und Mitochondrien-Fraktionen derselben Organe deutlich erhoht. Die Verabfolgung von Sammo mit niedrigem und hohem Niveau reduziert den Verbrauch von ATP in G, L und N relativ zur Positiv-Kontrolle. Die ADP- und AMP-Gehalte werden dagegen relativ reduziert. Auch die Myokinase-Aktivitat in denselben Organen wird relativ gehemmt. Die Aktivitaten von G-6-PD und 6-PGD in den Cytoplasma- und Mitochondrien-Fraktionen der genannten Organe werden ebenfalls relativ zur Positiv-Kontrolle erniedrigt.

Study of the anti-inflammatory activity of Populus tremula, Solidago virgaurea and Fraxinus excelsior.

Abstract: Aqueous/alcoholic extracts of Populus tremula, Solidago virgaurea and Fraxinus excelsior (components of Phytodolor ®N) were tested individually and in 3 different combinations for anti-inflammatory activity using carrageenan induced edema and/or adjuvant induced arthritis of the rat paw. The tested combinations as well as the individual extracts significantly reduced the paw edema to varying degrees and also dose dependently inhibited the arthritic paw volume. The anti-inflammatory activity of the combinations was respectively comparable to the tested doses of diclofenac

The effect of inhomogeneity and anisotropy on stoneley waves

Abstract: In this paper we study the dispersion equation of Stoneley waves that are travelling in an inhomogeneous elastic half-space over an anisotropic homogeneous elastic half-space. The phase velocity is calculated as a function of the wave number. The results indicate that the effect of anisotropy on such waves is small and can be neglected, while the effect of inhomogeneity is very pronounced. The results show that Stoneley waves do not exist after some cut-off value of the wave number.

Closed-form, localized wave solutions in optical fiber waveguides

Abstract: A novel bidirectional decomposition of exact solutions to the scalar wave equation has been shown to form a natural basis for synthesizing localized-wave (LW) solutions that describe localized, slowly decaying transmission of energy in free space. We present a theoretical feasibility study that shows the existence of LW solutions in optical fiber waveguides. As with the free-space case, these optical waveguide LW solutions propagate over long distances, undergoing only local variations. Four different source modulation spectra that give rise to solutions similar to focus wave modes, splash pulses, the scalar equivalent of Hillion's spinor modes, and the modified power spectrum pulses are considered. A detailed study of the modified power spectrum pulse is performed, the practical issues regarding the source spectra are addressed, and the distances over which such LW solutions maintain their nondecaying nature are quantified.

Crystal, magnetic and electric behaviour of CoMnxFe2?xO4 cubic ferrites

Abstract: Six powder samples of CoMn x Fe2−x O4 (O ⩽x ⩽1) were synthesized by using a ceramic sintering technique. X-ray powder diffraction patterns were obtained and confirmed the presence of single-phase spinel structure with no evidence of impurities. Lattice constants were determined. Differential thermal analysis measurements showed no variation in crystal phase with temperature. AC conductivity measurements at the temperature range (300–950 K) and for the frequency range (102–105 Hz) were also carried out and the Neel transition temperatures for all samples were determined. Mossbauer effect patterns revealed magnetic ordering for all compositions at room temperature. The obtained spectra were successfully analysed into two Zeeman sextets, could be attributed to the tetrahedral and octahedral sites. The different Mossbauer effect parameters were deduced and discussed. Neutron diffraction measurements were also performed where oxygen parameters and cation distributions were determined, and magnetic structure were studied. All obtained results from the different techniques support the Neel model of ferrimagnetism for such compounds.