Showing papers by "Cairo University published in 1979"

The Rift Valley fever epizootic in Egypt 1977–1978 2. Ecological and entomological studies

Abstract: Epidemiological factors related to the introduction, spread and maintenance of Rift Valley fever (RVF) virus were studied during the 1977-78 epizootic in Egypt, Culex pipiens is the most ubiquitous and prevalent mosquito species in the Nile Valley and Delta. Isolation of RVF virus from unengorged C. pipiens, and demonstration of laboratory transmission of the virus by this species, strongly implicate it as the chief vector in Egypt. Virus transmission to man also occurs by contamination when handling infected meat and by inhaling natural virus aerosols. Wild rodents apparently do not serve as RVF virus reservoirs. Domestic sheep, cattle, buffaloes, camels, goats, donkeys and dogs act as amplifying hosts. Over 30% of the camels sampled at the southern border of Egypt were serologically positive for antibodies to RVF virus and it appears likely that the virus was introduced into Egypt, either by these animals or by other vehicles from the south.

Use of barley in the egyptian late paleolithic.

Abstract: Several grains of barley have been recovered from archeological sites at Wadi Kubbaniya, near Aswan in Egypt. The sites are typical Late Paleolithic and are firmly dated between 18,300 and 17,000 years ago. They seem to represent a very early use of ground grain in the Nile Valley, and evidence is presented for its continued use over the subsequent 6000 years. The Egyptian findings possibly record an initial stage of food production, and if they indeed do, then they suggest that food production may not have been brought about by environmental stress and may not have led inevitably to radical social changes.

Optimum Design of Wind Tunnel Contractions

Abstract: A method for the design of low-speed wind tunnel contractions is presented. An optimum contraction is considered to be the shortest one that satisfies flow quality requirements in the test section; i.e., avoids any boundary-layer separation and supplies flow to the test section with a specified degree of uniformity. It is shown that by optimizing duct wall curvature distribution, it is possible to reduce contraction length to about one-half of that presently used in practice for a given test section flow quality. For example, a contraction with an area ratio of eight for a large wind tunnel can be as short as one inlet radius. The present method closely relates the shape and length of the contraction to the degree of flow quality required in the test section, to the contraction ratio, to the inlet flow Reynolds number, and to the viscous flow conditions in the settling chamber upstream of the contraction inlet. Presented are data to guide the design of a contraction of any combination of these parameters. The results of the study indicate that the avoidance of turbulent boundary-layer separation near the exit need not be a design driver; rather, the possibility of boundary-laye r relaminarizati on near the exit needs attention.

Active compensation of opamps

Abstract: A novel active compensation method for the finite gain bandwidth of operational amplifiers, when used in voltage-controlled voltage source structures, is given. In this method, a universal active compensation scheme is proposed which can be used with operational amplifier voltage-controlled voltage sources, when looked upon as a general threeport active building block. It is shown that phase shifts contributed by imperfect operational amplifiers are virtually eliminated over an extended frequency range. Experimental resnits are presented.

Studies on the biology of the mediterranean fruit fly ceratitis capitata

Abstract: The duration of the egg stage was significantly influenced by temperature. The threshold of egg development occurred at 11°. Preservation of eggs at 8°–9° for 2 days reduced hatchability from 98% to 48% and after 6 days no hatching occurred. Desiccation of eggs at 30% R.H. for 6 hr reduced hatchability from 98% to 12% and after 12 hr of desiccation no hatching occurred. Duration of the larval stage was affected by temperature. The zero point of larval development occurred at 5°. The highest percentage of pupation was at 27°, and at 35° most of the larvae failed to jump from the medium. Humidity had no effect on pupal duration within the same temperature. Pupal duration was, however, influenced by temperatures between 22° and 30°; with 35° being fatal. At 60% R.H., the threshold of pupal development occurred at 13°. The highest percentage of emergence was observed at 25° and 60% R.H. Males lived for an average of 36 and 25 days at 25° and 30° respectively, while the female longevity was 31 and 25.5 days for the same temperatures. Females produced more eggs at 25° (826 eggs/female) than at 30° (459 eggs/female). Females reared without males lived longer (67 days) and laid fewer eggs (248 eggs/female). ZUSAMMENFASSUNG UNTERSUCHUNGEN UBER DIE BIOLOGIE DER MITTELMEERFRUCHTFLIEGE, CERATITIS CAPITATA Bei der Mittelmeerfruchtfliege wird die Dauer der Eientwicklung durch die Temperatur wesentlich beeinflusst (Entwicklungsnullpunkt 11°). Die Lagerung der Eier bei 8°–9° verminderte die Schlupfrate nach 2 Tagen von 98% auf 48% und auf 0% nach 6 Tagen. Die Trocknung der Eier bei 30% R.F. reduzierte die Schlupfrate nach 6 Stunden von 98% auf 12% und nach 12 Stunden auf 0%. Die Larvenentwicklung war ebenfalls von der Temperatur abhangig (Entwicklungsnullpunkt 5°). Bei 27° war die Verpuppungsrate am hochsten, und bei 35° vermochten die meisten Tiere nicht mehr aus dem Nahrmedium zu springen. Die Dauer der Puppenentwicklung wurde von der Feuchtigkeit nicht beeinflusst, wohl aber von Temperaturen zwischen 22° und 30° (Entwicklungsnullpunkt 13°, totale Mortalitat bei 35°, Optimum bei 25° und 60% R.F.). Mannchen lebten im Durchschnitt 36 und 25 Tage, Weibchen 31 und 25 Tage bei einer Temperatur von 25° resp. 30°. Die Eiproduktion eines Weibchens war bei 25° hoher als bei 30° (826 resp. 459 Eier). Weibchen, welche getrennt von Mannchen gehalten wurden, lebten langer (67 Tage) und produzierten weniger Eier (248 Eier).

Effect of seasonal variation on immune system of the lizard, Scincus scincus

Abstract: In winter, the lizard, Scincus scincus, fails to form humoral antibodies to parenterally introduced rat erythrocytes. The response is slow and feeble in spring whereas, it is quick and vigorous in summer and autumn. In winter, the thymus of Scincus is involuted, white pulp of spleen highly depleted while, gut-associated lymphoid tissue is rather developed. By the beginning of spring, lymphoid organs start to regenerate. By the end of spring through midfall, the thymus presents a rich lymphoepithelial organization; splenic lymphoid aggregates are so developed that they become confluent and gut aggregates increase in number and size. The data suggest that, the kinetics and magnitude of the lizard's humoral response to foreign erythrocytes, correlate with the state of lymphoid tissue development which, in turn, is affected by seasonal variations.

Lymphoid tissues of the snake, Spalerosophis diadema, in the different seasons.

Abstract: The thymus in the snake, Spalerosophis diadema , is lymphoepithelial, clearly differentiated into cortex and medulla; it undergoes involution in both winter and summer During these seasons, the spleen is divided into distinct white and red pulps In spring and autumn, lymphocytes completely obscure the splenic stroma so that red and white pulp boundaries are obliterated Gut-associated lymphoid tissue (GALT) is extensively distributed along the entire gastrointestinal tract Structures resembling Peyer's patches, except in being composed of only two adjacent lymphoid accumulations, are prominent in the small intestine in winter and autumn, while decrease remarkably in number and size in spring and summer (the breeding season) In contrast, the gut-associated aggregates are numerous throughout the year Differential sensitivity to seasonal variation is suggested as a possible marker for functional lymphocyte populations in reptiles

A new concept of the anatomy of the anal sphincter mechanism and the physiology of defecation

Abstract: The central abscess is a new clinicopathologic entity which plays an important role in the pathogenesis of anorectal abscess and fistula Eight cases are presented The abscess occupies the central space, which lies between the longitudinal muscle and the base loop of the external sphincter The anatomic pattern and the clinical manifestations of the abscess are discussed The abscess extended, in some cases, to the subcutaneous space and perianal skin, to the anal canal proper, or to the intersphincteric spaces This is due to the fact that the central space communicates with all of the other perianal spaces along the central septa A new theory in the pathogenesis of anorectal suppuration and fistula is put forward It is believed that all anorectal abscesses or fistulas originate as central space infection which spreads to the other perianal spaces Proper diagnosis and early drainage of the central abscess prevent further spread of suppuration to other spaces

Factors affecting electrical conductivity of carbon black‐loaded rubber. II. Effect of concentration and type of carbon black on electrical conductivity of SBR

Abstract: Effect of the concentration of four types of carbon black, namely, HAF, FEF, ISAF and GPF, on the electrical conductivity of SBR (1502) was studied. The anomalous behavior of conductivity [σmin in σ(T) curves] becomes more pronounced as we approach a characteristic value of carbon concentration, F0, at which maximum anomaly occurs; F0 was found to depend on the type of carbon black. Moreover, the depth of the valley shape of the σ(T) curve increases with the particle size of carbon black used.

Modification of Corn Starch and Fine Flour by Acid and Gamma Irradiation. Part 1. Chemical Investigation of the Modified Products

Abstract: Fine flour from corn and the isolated starch were dextrinized in the presence of acid and irradiated with y-rays. Starch irradiated with high doses of y-rays was highly modified while fine flour was less affected. The irradiated starch was reduced with sodium borohydride and then hydrolysed. Erythritol and other compounds were identified in the hydrolysate. It was concluded that the C2-C3 bonds in the intermediate glucose units are probably broken by irradiation. Such hypothesis was confirmed by periodate oxidation, hydrolysis with α-amylase and ferricyanide number determination of the irradiated starch. Modifizierung von Maisstarke und Maisfeinmehl durch Saure und Gammabestrahlung.Teil 1. Chemische Untersuchung der modifizierten Produkte. Maisfeinmehl und die isolierte Starke wurden in Gegenwart von Saure dextriniert und mil γ-Strahlen behandelt. Mit hohen Dosen von γ-Strahlen bestrahlte Starke wurde stark modifiziert, wahrend das Feinmehl weniger stark angegriffen wurde. Die bestrahlte Starke wurde mil Natriumborhydrid reduziert und dann hydrolysiert. Erythritol und andere Verbindungen wurden in dem Hydrolysat identifiziert. Es wurde gefolgert, das die C2-C3-Bindungen in den Glucose-Einheiten wahrscheinlich durch die Bestrahlung gespalten werden. Diese Hypothese wurde durch Periodatoxidation, Hydrolyse mit α-Amylase und Bestimmung der Ferricyanidzahl bestatigt.

Transient electromagnetic fields of a vertical magnetic dipole on a two-layer earth

Abstract: The transient fields of a vertical magnetic dipole on a two-layer earth model are expressed in analytical form using two different approaches. In the first, the fields in the time domain are obtained as the inverse Laplace transforms of derived full wave time-harmonic solutions, while in the second, the concept of natural frequencies of the stratified earth is utilized. Comparison with a previously obtained approximate solution reveals that the latter is the late time part of the present solution. Important features in the waveforms of the surface fields due to step and pulsed current excitations are demonstrated by a variety of numerical examples. These features provide diagnostic means of sensing the earth's stratification, overburden thickness, and the ratio of conductivities of the layers.

Renal amyloidosis and schistosomiasis

Abstract: A retrospective study of 60 renal biopsies obtained from nephrotic subjects with schistosomiasis showed amyloid deposits in 10 cases. Distribution was usually segmental, mainly mesangial and overlapped with the conventional mesangioproliferative lesions of schistosomiasis. The invariable clinical presentation was proteinuria with generalized oedema of insidious onset and a slowly progressive or intermittent course. Differences from conventional schistosomal nephropathy are described. Response to anti-schistosomal treatment was very poor. Repeat renal biopsies showed no regression of the lesions. The possible links between schistosomiasis and amyloidosis are discussed and causes of amyloid deposition suggested.

Effect of inoculation with n(2)-fixing spirilla and azotobacter on nitrogenase activity on roots of maize grown under subtropical conditions.

Abstract: Inoculated and non-inoculated seedlings of maize were grown in fertile clayloam soils of Egypt and Belgium under subtropical conditions provided in a greenhouse. Acetylene-reducing activity and microbial counts were determined during a period ranging from 6 to 12 weeks after sowing. Irrespective of soil origin, N2-fixing spirilla and Azotobacter were common under maize cultivation. Inoculation resulted in a transitional increase in their numbers at early stages of growth. Nitrogenase activity was not detected in the rhizosphere of young plants. The maximum activities measured (81 to 1,436 nmol of C2H4 g−1 h−1) occurred close to the 50 to 70% silking stage. Inoculation with N2-fixing spirilla, particularly in Nile Delta soil, doubled the amount of N2 fixed in a late period of growth (12 weeks), whereas inoculation with Azotobacter had no noticeable effect.

Factors Improving the Steeping Process of Corn Grains. Part I. Effect of Steeping Process, Artificial Drying, Scratching and Storage

Abstract: It was found that the steeping of corn grains by using the usual counter-current system is more efficient for leaching protein than the continuous system. Artificial drying of corn grains at higher temperature decreases starch recovery and increases starch loss in byproducts. The scratching of presteeped corn grains reduced the steeping period by 40%. Storage of corn grains for a long period (9 months) reduced starch recovery by about 3%. Masnahmen zur Verbesserung des Quellprozesses von Maiskornern. Teil I. Einflus von Quellprozes, kunstlicher Trocknung, Anritzen und Lagerung Es wurde festgestellt, das die Quellung von Maiskornern bei Anwendung des ublichen Gegenstromverfahrens fur die Extraktion von Protein wesentlich wirkungsvoller ist als das kontinuierliche System. Die kunstliche Trocknung der Maiskorner bei hoherer Temperatur vermindert die Starkeausbeute und erhoht den Starkeverlust in Nebenprodukten. Das Anritzen der vorgequollenen Maiskorner verringerte die erforderliche Quellzeit um 40%. Die Lagerung von Kornermais uber einen langeren Zeitraum (9 Monate) verringerte die Starkeausbeute um etwa 3%.