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A Daoudi

Publications and source records attributed to A Daoudi.

14 recordsLinked to original sources
PubMed2006

Distortion and unwinding of the helical structure in polymer-stabilized short-pitch ferroelectric liquid crystal.

We report the effect of an anisotropic polymer network formed from an achiral photoreactive monomer in a short-pitch chiral SmC* phase on the distortion and the unwinding of the helical structure of the ferroelectric phase. The electro-optical behaviour and ferroelectric properties were experimentally determined for films containing various polymer concentrations. The critical field, E(u), for the transition from the distorted structure to the homogeneous state was measured as a function of polymer concentration. A linear increase of E(u) versus polymer concentration was observed, showing that the helical structure of the short-pitch SmC* phase was stabilized by the polymer network. This behaviour was expected to be a consequence of the increase of the apparent elastic constants of the ferroelectric liquid crystal stabilized by the anisotropic polymer network films. The polymer network morphology was investigated using atomic-force microscopy, revealing a twisted structure of the polymer fibers. This twisted structure was transferred onto a polymer network during the polymerization process within a short-pitch SmC* phase. The increase of the apparent elasticity can then be interpreted by a strong interaction between polymer network and the liquid-crystal molecules. From our experimental data, the coupling coefficient, W(p), characterizing this interaction was evaluated for all studied polymer concentrations.

Journal Article↗
PubMed2006

[Scaphoid enchondroma revealed by a fracture].

Enchondroma is a common bone tumor of hand. It is rarely localized in scaphoid. We report a new case of this tumor revealed by fracture. The diagnosis was suggested by standard radiography and confirmed then by anatomic pathology examination. Enucleation and bone graft with osteosynthesis yielded good result.

Adult↗
PubMed2006

[Insulated arm pilomatrixoma: A rare localization. A case report].

Pilomatrixoma also known as calcified epithelioma of Malherbe, is a rare benign cutaneous tumor. It is most commonly seen in the head and neck areas, during the first two decades of life. We report a 30-year-old female patient with a rare localisation of pilomatrixoma in the right arm. The pilomatrixoma was excised and at one year follow-up there has been no evidence of recurrence.

Adult↗
PubMed2005

Lyophilized preparations of bacteriocinogenic Lactobacillus curvatus and Lactococcus lactis subsp. lactis as potential protective adjuncts to control Listeria monocytogenes in dry-fermented sausages.

AIM: Study of the effectiveness of in situ bacteriocin production by lactic acid bacteria (LAB) to control Listeria monocytogenes in dry-fermented sausages. METHODS AND RESULTS: Two bacteriocin-producing strains: Lactococcus lactis subsp. lactis LMG21206 and Lactobacillus curvatus LBPE were grown in a pilot scale fermentor and lyophilized to be directly used in dry sausage fermentation. A commercial starter culture (Bel'meat SL-25) not inhibitory to L. monocytogenes (Bac- starter) was mixed (1 : 1) with each of the two lyophilized bacteriocin-producing strains to obtain starters active against the pathogen (Bac+ starter). Anti-Listeria effectiveness of the Bac+ starters was studied in dry-fermented sausages. The meat batter was experimentally contaminated with a mixture of four different strains of L. monocytogenes (10(2)-10(3) CFU g(-1)). The results showed that L. monocytogenes did not grow in any of the contaminated batches, but no significant decrease (P > 0.05) was observed either in the positive control (no added starter culture) or in samples fermented with the Bac- starter culture during the fermentation period and up to 15 days of drying. When the Bac+ starter contained Lb. curvatus LBPE, cell counts of L. monocytogenes decreased to below the detectable limit (<10 CFU g(-1)) after 4 h of fermentation and no survivors could be recovered by enrichment beyond day 8 of drying. When the Bac+ starter culture containing Lc. lactis LMG21206 was used, a decrease in Listeria counts to below the detectable limit was achieved after 15 days of drying. CONCLUSIONS: The bacteriocin-producing strains studied may be used as adjunct cultures for sausage fermentations to control the occurrence and survival of L. monocytogenes. SIGNIFICANCE AND IMPACT OF THE STUDY: Addition of the Bac+ strains, especially the Lb. curvatus strain would provide an additional hurdle to enhance the control of L. monocytogenes in fermented meat products.

Bacteriocins↗
PubMed2003

[Fenton's syndrome or scapho-capitate fracture (a case report)].

INTRODUCTION: Scapho-capitate fracture is a rare lesion and its mechanism is controversial. Forced extension seems to be the most frequent cause as this movement of the wrist induces scaphoid fracture by compression. Hyperextension of the wrist as a result of the scaphoid lesion, allows contact between the posterior margin of the radius and the neck of the capitate inducing a capitate fracture. MATERIALS AND METHODS: We report a case of Fenton's Syndrome, the patient was operated as an emergency by pining and immobilization of the carpus and thumb until bone consolidation had occurred. RESULTS: Consolidation was noted at 8 weeks with a good mobility of the wrist. DISCUSSION: Fenton's Syndrome is a rare lesion of the wrist. Analysis of our own case and a review of literature demonstrated extension as a causative mechanism, and the frequency of delayed diagnosis. Because of the presence of instability, scaphoid reduction and osteosynthesis is necessary. Immobilization of the carpus and thumb is essential until bony consolidation is obtained.

Adult↗
PubMed2003

[Coverage of tissue loss in the upper limb (ten cases)].

PURPOSE OF THE STUDY: The purpose of this study was to evaluate early cover of post-traumatic tissue loss in the upper limb. MATERIAL AND METHODS: We report 10 cases of tissue loss in the upper limb treated surgically by fasciocutaneous flaps or muscle flaps. The patients were aged from 14 to 60 years. Six patients underwent surgery as an emergency. Surgery consisted of a thorough debridement, internal fixation if required and soft tissue reconstruction as indicated. This was then followed by immediate flap cover. All had antibiotics during and after surgery. The coverage procedure was selected according to the site and its dimensions. We used 8 fasciocutaneous and 2 muscle flaps in our series. RESULTS: One flap underwent necrosis. The flaps otherwise showed good scaring and trophicity. All the patients were satisfied. DISCUSSION: Early or even immediate coverage of substantial tissue loss following trauma has been made possible because of the development of newer flap techniques. Meyer considers that the improved results can be explained by the fact that early cover prevents bone and tendon desiccation and is achieved before substantial bacterial colonisation can occur. Additionally it is a reliable procedure that brings in vascularised tissue, thereby contributing to reduced scarring of the underlying structures. It also permits immediate osteosynthesis thus avoiding the problems of external fixation. To us the key advantage of emergency skin cover is the fact that the operative field may become colonised but does not become infected. This gives the surgeon the freedom to undertake immediate reconstruction without the prospect of subsequent sepsis.

Adolescent↗
PubMed2003

Static and dynamic electro-optic properties of a SmC* phase in surface stabilized geometry and dispersed in the polymer matrix.

Comparative electro-optical measurements have been made on a ferroelectric liquid crystal (FLC) in surface stabilized geometry and confined to an ellipsoidal cavity within a polymer matrix. The static and dynamic electro-optical characteristics were measured for both systems and show qualitatively similar behaviours. A fast switching and important bistability were observed and characterized as a function of the applied electric field strength. The switching time between the two stable states of the surface stabilized cell was found to be longer than that found for the composite films. We argue that the faster switching dynamic of the FLC in cavities is due to the enhance of the rotational mobility of the molecules, probably (and partly) because of the "soft" anchoring character of the molecules at the cavity walls. Using a collective switching model in the high field regime, which assume a linear coupling between the spontaneous polarization and the local cavity electric field, we give an estimate of the rotational viscosity of the FLC molecules in the droplets.

Journal Article↗
PubMed2002

[Reposition flap techniques in fingertip amputations: 6 cases].

PURPOSE OF THE STUDY: The purpose of this study was to evaluate an alternative procedure for amputations distal to the distal interphalangeal joint: the reposition flap. MATERIALS AND METHODS: The reposition flap was used for 6 patients who underwent fingertip amputations in an emergency setting. Pulp was excised on the amputated segment and the remaining bone and nail bed were reattached to the proximal stump with a Kirschner wire. The pulp was reconstructed with a local advancement and sensitive flap. The patients were aged 18 to 44 years and had been victims of work accidents. All refused finger shortening. RESULTS: The fingers showed good scarring and good trophicity. Two-point discrimination was 6 mm. Bony fusion was constant but all distal interphalangeal joints remained stiff. Cosmetic results were correct except for two cases of claw nail formation. DISCUSSION: Fingertip amputations have been widely reported. Methods have varied from directed scarring to partial toe transfer. These situations present two types of challenge: insensitivity of the volar aspect or an overly sensitive pulp; cosmetic presentation and function of the dorsal aspect due to the complex role of the nail. Distal reimplantation remains the best technique, but the reposition flap offers an interesting alternative in case of failure or for patients who do not accept finger shortening. The advantage of the reposition flap is that it preserves finger length and the nail. Work stoppage and intolerance to cold can be an inconvenience due to the long time required for wound healing.

Adolescent↗
PubMed1999

Potential Energy Curves and Electronic Structure of Copper Nitrides CuN and CuN+ Versus CuO and CuO+

Ab initio configuration interaction calculations for the diatomic CuO, CuN, CuO+, and CuN+ have been carried out, and potential energy curves are reported for several low-lying states of these systems. The electronic structure and bonding, not yet known for the neutral copper nitride and its cation, are examined and compared to those of the copper oxide systems. We find that the ground states of these systems are X2Pi (CuO), X3Sigma- (CuN), X3Sigma- (CuO+), and X4Sigma- (CuN+); their first low-lying excited states Y2Sigma+, 1Delta, 1Delta, and 2Pi are located at 0.69, 1.45, 2.32, and 2.09 eV, respectively. For CuO we found two unobserved quartet states, namely 4Sigma- (Te = 1.09 eV) and 4Pi (Te = 1.86 eV). We report equilibrium structural parameters for various electronic states of the studied systems and compare them with experimental values, where it is possible. Copyright 1999 Academic Press.

Journal Article↗
PubMed1997

Episodes of low-dimensional self-organized dynamics from electroencephalographic alpha-signals.

Self-organized neuronal dynamics revealed by cortical alpha-rhythms occur as episodes, which are rarely observed without extraction of the alpha-band from the other spectral components. Three episodes of an unusually long duration of 10 s, two with no signal processing after data recording at the clinic, are described and show evidence of low-dimensional alpha-dynamics. The evidence is gained from an analysis of scaled structures appearing in families of slope curves of the correlation integrals and is checked against time reparametrization. The data for the two unprocessed 10-s episodes are used for a test of the methodology, as well as a re-examination of the adequacy of the model of an autonomous dynamic system in steady state and of the concept of an attractor in brain dynamics investigations. Striking evidence for the model's inadequacy is provided by the episode of subject S1. In this example five consecutive overlapping 6-s sections do show evidence for low-dimensional dynamics, whereas the 10-s section containing those sections does not. The episode of subject 1 provides an example of alpha-activity which may involve self-organized dynamics extending down to low frequencies. The system (the neuronal network) showing episodes of attractor-ruled dynamics, under conditions of blurred and smoothly fading out evidence that it stays on an attractor, is designated as being ruled by a 'shadow-attractor'. This concept is compared with that of a 'quasi-attractor' introduced by H. Haken in studies of physiological systems. One possible mechanism for the observed episodes is proposed, based on a time-dependent number of enslaved sub-systems.

Adult↗
PubMed1985

Haemonchus contortus and Ostertagia circumcincta: fenbendazole treatment and abomasal permeability changes in sheep.

Effects of fenbendazole (7.5 mg/kg of body weight infused during 90 minutes) on abomasal transmural potential difference (PD), pH, and ionic concentrations were determined in 8 lambs fitted with permanent abomasal cannulae. Four sheep were treated before inoculation and on day 28 after inoculation, with 200,000 3rd-stage Ostertagia circumcincta larvae and 4 others were similarly inoculated with 15,000 3rd-stage Haemonchus contortus larvae. In worm-free lambs, the unique effect was an increase in Na+ concentration of the abomasal contents. The O circumcincta or H contortus-inoculated lambs had an increase in PD, pH, and Na+ concentrations. Treatment further increased these concentrations, but the effects on PD occurred and ceased earlier in sheep inoculated with O circumcincta than in those inoculated with H contortus. The results indicated that part of the changes were linked to substances produced by the parasites or by the host. The increase in PD and pH was associated with a decrease in K+ concentration and indicated that these substances stimulated HCO3- transfer.

Abomasum↗