Ahmed Saad

Bio: Ahmed Saad is an academic researcher from Al-Azhar University. The author has contributed to research in topics: CMOS & Medicine. The author has an hindex of 4, co-authored 20 publications receiving 105 citations. Previous affiliations of Ahmed Saad include LSI Corporation & Suez Canal University.

Morphology of the testis of the one-humped camel in relation to reproductive activity.

Abstract: Histological and morphometric studies on the camel testis have been carried out systematically at regular monthly intervals during a period of one year. The testicular weight was minimal during summer, while the maximum weight was attained during the coldest months from November until March. Diameters of the seminiferous tubules were multiphasic with a tendency to be wider during summer. The ratio of the area occupied by seminiferous tubules to that occupied by interstitial tissue revealed that the latter occupied a larger area than that of the seminiferous tubules during winter, while a reversed relationship occurred from March onwards and was especially marked after April, i.e. in summer. In addition, spermatogenesis was noted in all testes examined throughout the year; however, there was a difference in the quality and quantity of spermatogenic cells between the monthly groups evaluated. November, December and January were the months in which spermatogenic activity was most striking. A correlation was established between testicular weight, amount and quality of testicular interstitial tissue, spermatogenesis and epididymal sperm content and, hence, testicular function on the one hand and season of the year on the other hand. The cyclic structural changes in the testis appeared to be in parallel with the rutting activity of the camel. It was suggested also that the camel is not a typical seasonal breeder as it does not go through sexual quiescence. The reproductive activity of the camel builds up during September and October, and the animal is in actual rut during November, December, January and February, with a drop in March and thereafter.

A high wide band PSRR and fast start-up current mode bandgap reference in 130nm CMOS technology

Abstract: This paper presents a high wide band power supply rejection ratio (PSRR) current mode bandgap reference (BGR) with a fast startup performance. The BGR includes three main enhancement techniques to improve the PSRR. The proposed design is implemented in 130nm CMOS technology. It only consumes 50μA from a 1.8V supply. The BGR provides 850mV reference voltage and has a power supply rejection ratio (PSRR) of 130dB from DC to 100Hz and more than 110dB till 100MHz. The temperature coefficient (TC) is 10 ppm/°C from −40°C to 125° C. The Bandgap start-up time is 70ns.

Multimodal Carbonates: Distribution of Oil Saturation in the Microporous Regions of Arab Formations

Abstract: Perhaps as much as 50% of the oil-in-place in carbonate formations around the world is locked away in the easy to bypass microporosity. If some of this oil is unlocked by the improved recovery processes focused on tight carbonate formations, the world may gain a major source of lower-rate power over several decades. Here, we overview the Arab D formation in the largest oil field on earth, the Ghawar. We investigate the occurrence of microporosity of different origins and sizes using scanning electron microscopy (SEM) and pore casting techniques. Then, we present a robust calculation of the probability of invasion and oil saturation distribution in the nested micropores using mercury injection capillary pressure data available in the literature. We show that large portions of the micropores in Arab D formation would have been bypassed during primary drainage unless the invading crude oil ganglia were sufficiently long. We also show that, under prevailing conditions of primary drainage of the strongly water-wet Arab formations in the Ghawar, the microporosity there was invaded and the porosity-weighted initial oil saturations of 60–85% are expected. Considering the asphaltenic nature of crude oil in the Ghawar, we expect the invaded portions of the pores to turn mixed-wet, thus becoming inaccessible to waterflooding until further measures are taken to modify the system’s surface chemistry and/or create substantial local pore pressure gradients.

Surgery and outcome of infective endocarditis in octogenarians: prospective data from the ESC EORP EURO-ENDO registry

Abstract: High mortality and a limited performance of valvular surgery are typical features of infective endocarditis (IE) in octogenarians, even though surgical treatment is a major determinant of a successful outcome in IE. Data from the prospective multicentre ESC EORP EURO-ENDO registry were used to assess the prognostic role of valvular surgery depending on age. As compared to < 80 yo patients, ≥ 80 yo had lower rates of theoretical indication for valvular surgery (49.1% vs. 60.3%, p < 0.001), of surgery performed (37.0% vs. 75.5%, p < 0.001), and a higher in-hospital (25.9% vs. 15.8%, p < 0.001) and 1-year mortality (41.3% vs. 22.2%, p < 0.001). By multivariable analysis, age per se was not predictive of 1-year mortality, but lack of surgical procedures when indicated was strongly predictive (HR 2.98 [2.43–3.66]). By propensity analysis, 304 ≥ 80 yo were matched to 608 < 80 yo patients. Propensity analysis confirmed the lower rate of indication for valvular surgery (51.3% vs. 57.2%, p = 0.031) and of surgery performed (35.3% vs. 68.4%, p < 0.0001) in ≥ 80 yo. Overall mortality remained higher in ≥ 80 yo (in-hospital: HR 1.50[1.06–2.13], p = 0.0210; 1-yr: HR 1.58[1.21–2.05], p = 0.0006), but was not different from that of < 80 yo among those who had surgery (in-hospital: 19.7% vs. 20.0%, p = 0.4236; 1-year: 27.3% vs. 25.5%, p = 0.7176). Although mortality rates are consistently higher in ≥ 80 yo patients than in < 80 yo patients in the general population, mortality of surgery in ≥ 80 yo is similar to < 80 yo after matching patients. These results confirm the importance of a better recognition of surgical indication and of an increased performance of surgery in ≥ 80 yo patients.

Camels' reproductive and physiological performance traits as affected by environmental conditions

Abstract: Resumen en: The male camel is described as a seasonal breeder with a marked peak in sexual activity (the rut) during the breeding season and it is generally thought ...

Low Noise Wide Tuning Range Quadrature Ring Oscillator for Multi-Standard Transceiver

Abstract: This letter presents a low phase noise quadrature ring oscillator with new start-up circuit The oscillator architecture is a two-stage differential ring with an additional pair of transition-assistance transistors The circuit was implemented in 018 mum CMOS technology and the measured tuning range of the prototype device is from 17 GHz to 55 GHz and figure of merit (FOM) is -162 dB The proposed area of application is the core of the local oscillator in a multi-standard wireless transceiver