ayoub rachid | Faculté des sciences et techniques settat (original) (raw)

Papers by ayoub rachid

In modern days, railway systems are a critical catalyst for growth of cities and regions. Railway... more In modern days, railway systems are a critical catalyst for growth of cities and regions. Railway infrastructure is under pressure to provide higher capacity to the complex rail system. Railway capacity is governed not only by a number of trains over a time window, but is also by its infrastructure’s geometry and alignment, structural components, and track conditions. Railway urban turnout is a special track system used to divert a train from a particular direction or a particular track onto other directions or other tracks. It is a structural grillage system that consists of steel rails, points (or called ‘switches’), crossings (special track components), steel plates, rubber pads, insulators, fasteners, screw spikes, beam bearers (either timber, polymer, steel or concrete), ballast and formation. It is often found that most train-turnout interaction induces coupling dynamic transient loading on the track components, especially on curves. In many cases, trains divert from one tange...

Railway concrete sleepers have been generally used in ballasted railway track around the world fo... more Railway concrete sleepers have been generally used in ballasted railway track around the world for over 50 years. They are commonly used to redistribute wheel forces onto track structure and to assure stable track gauge for safe passages of rolling stocks. The dynamic behaviours of railway sleepers are commonly well known; however, its damping characteristic is often neglected. With the increased demand for heavier and faster trains, the nature of track forces applying onto each track components is no longer static or quasi-static. Statistically, almost a quarter to track load spectra is typically of transience and high intensity. The ignorance of damping can no longer be persisted as pre-mature damage or failure of track components can take place at a faster rate. A single sleeper failure may not affect open, plain track operations but it can give rise to the risks of rail breaks at rail joints, welds, bridge ends, switches and crossings, curved track, etc. Such the risks can later...

Pediatric Transplantation, 2006

Abstract: Over a 15-yr period of observation, among the 205 children who underwent liver transpla... more Abstract: Over a 15-yr period of observation, among the 205 children who underwent liver transplantations, one of them developed a particular type of late graft dysfunction with clinical and histological similarity to autoimmune hepatitis. The patient had α1-antitrypsin deficiency and did not previously have autoimmune hepatitis or any other autoimmune disease before transplantation. Infectious and surgical complications were excluded. After repeated episodes of unexplained fluctuations of liver function tests and liver biopsies demonstrating reactive or a biliary pattern, without any corresponding alteration of percutaneous cholangiography, a liver-biopsy sample taken 4 yr after the transplant showed active chronic hepatitis progressing to cirrhosis, portal lymphocyte aggregates, and a large number of plasma cells. At that time, autoantibodies (gastric parietal cell antibody, liver–kidney microsomal antibody, and anti-hepatic cytosol) were positive and serum IgG levels were high. Based on these findings of autoimmune disease, a diagnosis of ‘de novo autoimmune hepatitis’ was made. The treatment consisted of reducing the dose of cyclosporine, reintroduction of corticosteroids, and addition of mycophenolate mofetil. After 19 months of treatment, a new liver-biopsy sample showed marked reduction of portal and lobular inflammatory infiltrate, with regression of fibrosis and of the architectural disruption. At that time, serum autoantibodies became negative. The last liver-biopsy sample showed inactive cirrhosis and disappearance of interface hepatitis and of plasma cell infiltrate. Presently, 9 yr after the transplantation, the patient is doing well, with normal liver function tests and no evidence of cirrhosis. Her immunosuppressive therapy consists of tacrolimus, mycophenolate mofetil, and prednisolone. In conclusion, the present case demonstrates that de novo autoimmune hepatitis can appear in liver-transplant patients despite appropriate anti-rejection immunosuppression, and triple therapy with tacrolimus, mycophenolate mofetil, and prednisolone could sustain the graft and prevent retransplantation.

Chinese Physics Letters, 2007

The effect of Zn doping on the magnetic properties of CdCr2S4 systems is studied by mean field th... more The effect of Zn doping on the magnetic properties of CdCr2S4 systems is studied by mean field theory and high-temperature series expansion (HTSE). The nearest neighbouring and the next-neighbouring super-exchange interactions J1(x) and J2(x) are evaluated for the spinel system ZnxCd1-xCr2S4 in the range 0<=x<=1. The intra-planar and the inter-planar interactions are deduced. The HTSE combined with the Padé approximant method (PA) is applied to the spinel system ZnxCd1-xCr2S4. The magnetic phase diagram, i.e. TC versus dilution x, is obtained. The critical exponents associated with the magnetic susceptibility γ and the correlation length ν are deduced. The obtained theoretical results are in agreement with the experimental data obtained by magnetic measurements.

Revue De Pneumologie Clinique, 2007

Anesthesiology, 2001

... Canadian Journal of Anaesthesia-Journal Canadien D Anesthesie Prophylactic methylene blue in ... more ... Canadian Journal of Anaesthesia-Journal Canadien D Anesthesie Prophylactic methylene blue in a patient with congenital methemoglobinemia Baraka, AS; Ayoub, CM; Yazbeck-Karam, V; Kaddoum, RN; Gerges, FJ; Hadi, UM; Dagher, CM Canadian Journal of Anaesthesia ...

Archives De Pediatrie, 1997

Arch Pt~diatr ] 997;4:629-638 0 Elsevier, Paris M~moire original La lithiase urinaire de renfant:... more Arch Pt~diatr ] 997;4:629-638 0 Elsevier, Paris M~moire original La lithiase urinaire de renfant: contributions de l'ananm~se, de l'explorafion biologique et de I'analy~ physique des calcuis au diagnostic 6tiologique A Kamoun ~, A Zghal 2, M Daudon ~', S Ben Ammar 4, L Zer¢lli ~, J Abdelmoula 2, B Chaouachi 5, T Houissa 5, C Belkahia ;, R Lakhoua ~

Archives De Pediatrie, 1995

La lithotritie extracorporelle a transform6 la prise. en charge des lithiases urinaires, y compri... more La lithotritie extracorporelle a transform6 la prise. en charge des lithiases urinaires, y compris de celles observ6es au cows de I'hyperoxahnie primaim & type I au cows de htqueue l'ablation chirurgicak des cakuls a QU s'awompgner d'une &gradatioo & la fonction t&ale. OkwrWiorrs. -Trois enfants non apparentts ages de 8, 10 et 11 ans, respcctivcmont, avec we hyperoxahtrie primaire de type I, or.! presente des coliques DCphrCtiques a r&t?tition (deux enfants) ou une anernie fun enfant). Deux des enfants avaient mte insuffktnce r&tale chronique. t_es radiogra@ies de I'ahdotnen et les Cchograpities ont montre la presence de calculs volumineux des deux c&es. Des seances de lithotritie extracorporehe ant et6 propoks; 3 seances on1 suffi B retirer compRtement les cakuls chew un maiade et 4 seances ont permis d'obtenir mm disparition Qartielle des calculs chea Ie deuxibme apms qu'une infection urinaire s'est ddveloQ#e lots de la premiere seance avec augmentatton traositoire de la creatinindmie chez ce patient. Qlusieurs dances n'ont pas pe.tmis la fragmentation des calculs chex le troisRme enfant. Conclusion. -La lithotritie extracorporelle merite d'i?tre essay& pour obtcnir la disparition des calculs chex Ies patients avec hyperoxahtrie primaire puisqu'elle ne semble pas s'accompagner d'tme aggravation de la fonction r&tale.

Journal of Physics-condensed Matter, 2008

The critical properties of a ferrimagnetic spinel system (AB2X4, A and B are magnetic ions) are s... more The critical properties of a ferrimagnetic spinel system (AB2X4, A and B are magnetic ions) are studied by the method of exact high-temperature series expansions. Terms up to seventh order were computed for the magnetic susceptibility \chi=\sum_{n=0}^7 a_n (\frac {1}{k_{\mathrm {B}} T})^n . The calculations are given for the three nearest neighbours' exchange integrals JAA,JAB and JBB. The Padé approximants method is used to estimate the critical exponent γ associated with the magnetic susceptibility. A net variation of γ with exchange couplings has been observed. This variation presents some unusual characteristics. The magnetic asymmetric interactions and the competition between the exchange interactions are important for the magnetic phase transition in ferrimagnetic spinels. We make comparisons with experiment by studying real Heisenberg spinel ferrite systems ACr2S4 (A = Fe,Co). The results of γ and Tc obtained by the present approach are in agreement with the experimental values.

Annales De Pathologie, 2004

ABSTRACT

Pediatric Nephrology, 1999

The composition of urinary stones in children depends on socioeconomic conditions and hygiene, ge... more The composition of urinary stones in children depends on socioeconomic conditions and hygiene, geographical area, and dietary habits. We analyzed urinary stones from 120 consecutive Tunisian children (81 males, 39 females) aged 5 months to 15 years. The stone was located in the upper urinary tract in 91 cases (76%). Stone analysis included both a morphological examination and an infrared analysis of the nucleus and the inner and peripheral layers. The main components of bladder calculi were whewellite (69%) and struvite (22%), whereas the main component of upper urinary tract calculi was whewellite (67%). The nucleus of bladder stones was composed of ammonium urate (45%), struvite (28%), cystine (10%), and carbapatite (7%). The nucleus of kidney and ureteral calculi was mainly composed of ammonium urate (38%), whewellite (24%), carbapatite (13%), or struvite (11%). Based on stone composition, urinary tract infection was involved in the nucleation or growth of a third of calculi. Endemic urolithiasis involving simultaneous nutritional, metabolic, and infectious factors, and defined by its nucleus composed of ammonium urate without struvite, represented 40% of cases. Exclusive metabolic factors – including genetic diseases such as primary hyperoxaluria, cystinuria, and hypercalciuria – were responsible for less than 25% of cases.

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