Cairo University

About: Cairo University is a education organization based out in Giza, Egypt. It is known for research contribution in the topics: Population & Medicine. The organization has 33532 authors who have published 55581 publications receiving 792654 citations. The organization is also known as: Fuad I University & King Fuad I University.

Variational method for the nonlinear dynamics of an elliptic magnetic stagnation line

Abstract: The nonlinear evolution of the kink instability of a plasma with an elliptic magnetic stagnation line is studied by means of an amplitude expansion of the ideal magnetohydrodynamic equations. Wahlberg et al. [12] have shown that, near marginal stability, the nonlinear evolution of the stability can be described in terms of a two-dimensional potential U(X,Y), where X and Y represent the amplitudes of the perturbations with positive and negative helical polarization. The potential U(X,Y) is found to be nonlinearly stabilizing for all values of the polarization. In our paper a Lagrangian and an invariant variational principle for two coupled nonlinear ordinal differential equations describing the nonlinear evolution of the stagnation line instability with arbitrary polarization are given. Using a trial function in a rectangular box we find the functional integral. The general case for the two box potential can be obtained on the basis of a different ansatz where we approximate the Jost function by polynomials of order n instead of a piecewise linear function. An example for the second order is given to illustrate the general case. Some considerations concerning solar filaments and filament bands (circular or straight) are indicated as possible applications besides laboratory experiments with cusp geometry corresponding to quadripolar cusp geometries for some clouds and thunderstorms.

Defective sexuality and female circumcision: the cause and the possible management.

Abstract: Aim: To verify the effect of circumcision on female sexuality and to define the need for clitorolabioplasty in these cases. Methods: Thirty uncircumcised controls, 30 minorly circumcised, 30 minorly circumcised mutilated, and 57 circumcised cases having clitoral cysts were selected on random bases at Kasr El Aini School of Medicine. Sexuality was assessed by a special questionnaire sheet prepared by the authors to fit the circumcised cases. Clitorolabioplasty and clitoral cyst excision were also done in cases of sexual defects. Results: Sexuality was not affected in minorly circumcised cases. However, sexuality was markedly affected in the mutilated cases. The scores for sex desire and arousal and for orgasm were especially affected in such cases. These defects were not detected in cases having clitoral cysts until late, when cysts enlarged. The role of clitorolabioplasty in restoration of sexuality was confirmed. The loss of certain clitoral and labial bulk, necessary for orienting the woman towards her genitalia and initiating her interest in their function, was responsible for the occurrence of such defects; this was able to be restored by surgery. Conclusion: Counseling parents about these sexual defects and asserting the need for correcting the mutilation, which resulted from these circumcisions, are effective steps in banning such procedures.

Design of Si/SiGe heterojunction complementary metal-oxide-semiconductor transistors

Abstract: An optimized Si/SiGe heterostructure for complementary metal-oxide semiconductor (CMOS) transistor operation is presented. Unlike previous proposals, the design is planar and avoids inversion of the Si layer at the oxide interface. The design consists of a relaxed Si/sub 0.7/Ge/sub 0.3/ buffer, a strained Si quantum well (the electron channel), and a strained S/sub 1-x/Ge/sub x/ (0.7>x>0.5) quantum well (the hole channel). The channel charge distribution is predicted using a 1-D analytical model and quantum mechanical solutions. Transport is modeled using 2-D drift-diffusion and hydrodynamic numerical simulations. An almost symmetric performance of p- and n-transistors with good short-channel behavior is predicted. Simulated ring oscillators show a 4- to 6-fold reduction in power-delay product compared to bulk Si CMOS at the 0.2-/spl mu/m channel length generation.

Bacterial foraging oriented by particle swarm optimization strategy for PID tuning

Abstract: Proportional integral derivative (PID) controller tuning is an area of interest for researchers in many disciplines of science and engineering. This paper presents a new algorithm for PID controller tuning based on a combination of the foraging behavior of E coli bacteria foraging and Particle Swarm Optimization (PSO). The E coli algorithm depends on random search directions which may lead to delay in reaching the global solution. The PSO algorithm may lead to possible entrapment in local minimum solutions. This paper proposed a new algorithm Bacteria Foraging oriented by PSO (BF-PSO). The new algorithm is proposed to combines both algorithms' advantages in order to get better optimization values. The proposed algorithm is applied to the problem of PID controller tuning and is compared with conveniently Bacterial Foraging algorithm and Particle swarm optimization.