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Biomedical subjects

A Benyoussef

Publications and source records attributed to A Benyoussef.

At least 19 recordsLinked to original sources
PubMed2004

Laparoscopic promontory sacral colpopexy: is the posterior, recto-vaginal, mesh mandatory?

OBJECTIVE(S): The aim of our retrospective study was to determine if systematic placement of a posterior mesh, in addition to an anterior vesico-vaginal mesh, is necessary for laparoscopic treatment of pelvic organ prolapse. METHODS: A laparoscopic promontory sacral colpopexy was performed in 108 patients, including 55 patients with a concurrent laparoscopic Burch procedure (50.9%). We compared 33 patients treated with a single anterior mesh (SAM) and 71 treated with a double, anterior and posterior, mesh (DM). RESULTS: The difference between the SAM and DM groups was statistically significant in terms of posterior compartment failure (rectocele and/or enterocele): 31.3% and 5.9%, respectively (p=0.0006). This significant difference persisted in the Burch (B) group (p=0.001), but not in the non-Burch (NB) group (p=0.98). Among the SAM group, this difference between the B and NB groups, was significant (57.1% versus 0%; p=0.0015) and above all not a single posterior failure was observed in the NB group. CONCLUSION(S): The placement of a posterior mesh, if highly effective, appeared unnecessary in the absence of an associated Burch procedure or a patent posterior prolapse. The posterior mesh also increased risk of postoperative complications and side effects.

Adult↗
PubMed2003

Anisotropy effect on two-dimensional cellular-automaton traffic flow with periodic and open boundaries.

Using computer simulations we investigate, in a version of the Biham-Middleton-Levine model with random sequential update on a square lattice, the anisotropy effect of the probabilities of the change of the motion directions of cars, from up to right (p(ur)) and from right to up (p(ru)), on the dynamical jamming transition and velocities under periodic boundaries on one hand and the phase diagram under open boundaries on the other hand. However, in the former case, the sharp jamming transition appears only for p(ur)=0=p(ru)=0 (i.e., when the cars alter their motion directions). In the open boundary conditions, it is found that the first-order line transition between jamming and moving phases is curved. Hence, by increasing the anisotropy, the moving phase region expands as well as the contraction of the jamming and maximal current phases takes place. Moreover, in the anisotropic case, the transition between the jamming phase (or moving phase) and the maximal current phase is of second order while in the isotropic case, and when each car changes its direction of motion at every time step (p(ru)=p(ur)=1), the transition is of first order. Furthermore, in the maximal current phase, the density profile decays with an exponent gamma approximately 1/4.

Journal Article↗
PubMed2003

Complete solo laparoscopic radical prostatectomy: initial experience.

OBJECTIVES: To demonstrate the feasibility of "complete solo" (CS) laparoscopic radical prostatectomy (LRP) performed solely with robotic manipulation of the laparoscope and without any human assistant at all. A comparison was made between CS LRP and the standard technique to identify the advantages and drawbacks. METHODS: Sixteen consecutive patients undergoing CS LRP were compared with the last 16 patients undergoing standard LRP. The standard procedure was performed with five trocars and one human assistant. Therefore, the surgeon had three instruments immediately available and could switch quickly from one to another, while the assistant held the laparoscope and a retractor. The CS method used a voice-controlled robotic arm to manipulate the laparoscope and a mechanical arm for the assisting instrument. RESULTS: The mean operative time in the CS and standard groups was 324 and 347 minutes, respectively (P >0.5). An additional human assistant was required, for 1 hour, in 3 patients of each group. No significant difference was noted between the two groups in terms of catheterization time, hospital stay, positive margin rate, complications, short-term cancer control, or functional results. The CS method has been demonstrated to be highly cost-effective compared with the standard technique. CONCLUSIONS: The CS LRP is feasible and compares favorably with the standard technique. It offers unique advantages in terms of direct control of the operative view, standardization of the assistance, and higher stability of the laparoscope, thus greatly enhancing the surgeon's comfort. The diminished need for human operative assistance provides significant economic and organizational benefits.

Aged↗
PubMed2002

Edge wetting of an Ising three-dimensional system.

The effect of edge on wetting and layering transitions of a three-dimensional spin-1/2 Ising model is investigated, in the presence of longitudinal and surface magnetic fields, using mean field theory and Monte Carlo simulations. For T=0, the ground state phase diagram shows that there exist only three allowed transitions, namely, surface and bulk transition, surface transition, and bulk transition. However, there exist a surface intralayering temperature T(s)(L), above which the surface and the intralayering surface transitions occur. While the bulk layering and intralayering transitions appear above another finite temperature T(b)(L)(>or=T(s)(L)). These surface and bulk intralayering transitions are not seen in the perfect surfaces case. Numerical values of T(s)(L) and T(b)(L), computed by Monte Carlo method are found to be smaller than those obtained using mean field theory. However, the results predicted by the two methods become similar, and are exactly those given by the ground state phase diagram, for very low temperatures. On the other hand, the behavior of the local magnetizations as a function of the external magnetic field, shows that the transitions are of the first order type. T(s)(L) and T(b)(L) decrease when increasing the system size and/or the surface magnetic field. In particular, T(b)(L) reaches the wetting temperature T(w) for sufficiently large system sizes.

Journal Article↗
PubMed2002

Continuously varying critical exponents in a sandpile model with internal disorder.

A sandpile model with an internal disorder is presented. The updating of critical sites is done according to a stochastic rule (with a probabilistic toppling q). Using a unified mean-field theory and numerical simulations, we have shown that the criticality is ensured for any value of q. The static critical exponents have been calculated and found to be the same as those obtained for the deterministic sandpile model, which is a particular case of the stochastic model. They have a universal q-independent behavior. In the limit of slow driving, we have developed a relation between our model and the branching process in order to compute the size exponent tau. It presents a continuous variation with the parameter of toppling q.

Journal Article↗
PubMed2001

Kinetic Ashkin-Teller model with competing dynamics.

We study a two-dimensional nonequilibrium Ashkin-Teller model based on competing dynamics induced by contact with a heat bath at temperature T, and subject to an external source of energy. The dynamics of the system is simulated by two competing stochastic processes: a Glauber dynamics with probability p, which simulates the contact with the heat bath; and a Kawasaki dynamics with probability 1-p, which takes into account the flux of energy into the system. Monte Carlo simulations were employed to determine the phase diagram for the stationary states of the model and the corresponding critical exponents. The phase diagrams of the model exhibit a self-organization phenomenon for certain values of the fourth coupling interaction strength. On the other hand, from exponent calculations, the equilibrium critical behavior is preserved when nonequilibrium conditions are applied.

Journal Article↗
PubMed1976

Sudan: national health programme and primary health care, 1977/78-1983/84.

As a follow-up to the national health programming process developed in 1975 in Sudan, a primary health care programme for the whole country was formulated with assistance from WHO. In this article the methods used in the programming and formulation are described and discussed. These methods ensured an intersectoral approach on which technical, cultural, socioeconomic, financial, and political considerations were based. Areas in the field of health and rural development requiring government and community action during the period 1977/78-1983/84 are identified. Details on the strategies for population coverage of rural and nomadic communities with primary health care are given. Fundamental to these strategies is community participation in the development of primary health care within community development as a whole.The guiding principles of these strategies are their technical, political, social and financial feasibility. The social relevance of the primary health care programme for the community and the developmental sectors is emphasized.

Health Planning↗