Modeling and simulation of high speed milling centers dynamics

High speed machining is a milling operation in industrial production of aeronautic parts, molds and dies. The parts production is being reduced because of the slowing down of the machining resulting from the tool path discontinuity machining strategy. In this article, we propose a simulation tool of the machine dynamic behavior, in complex parts machining. For doing this, analytic models have been developed expressing the cutting tool feed rate. Afterwards, a simulation method, based on numerical calculation tools, has been structured. In order to validate our approach, we have compared the simulation results with the experimental ones, for the same examples

Trans-sinusal frontal approach for olfactory groove meningiomas

Background We report on our experience with the trans-sinusal frontal approach in removing olfactory groove meningiomas in the department of neurosurgery of Univesity Hospital Center of Annaba (Algeria).Methods Ten tumours were operated on by the trans-sinusal frontal approach, using a bicoronal incision, tree tumours developed on one side, and there were seven bilateral olfactosellar tumours. Our procedure : steotomy of the anterior wall of the frontal sinus was performed with an oscillating saw. The posterior wall of the sinus was resected and the tumour was removed through a real subfrontal route along the plane of the anterior skull base. Ethmoidal blood supply was early controlled at the initial stages of the operation, allowing avascular tumour debulking. Tumour extensions toward the sella and the optic canals were removed without brain retraction. Results Seven patients made a good neurologic recovery. Two was dead in the 24 hours after intervention and one four days after. Olfactory nets were preserved on the contralateral side in unilateral tumours. Conclusions The trans-sinusal frontal approach represents an excellent way for tumours developed in the central anterior skull base, especially for olfactory groove meningiomas, whatever their size

Patients with complicated Pott's disease: Management in a rehabilitation department and functional prognosis

AbstractObjectiveThe objective is to study the rehabilitation management and to assess autonomy in daily life activities as well as walking recovery in patients with complicated Pott's disease.Patients and methodsRetrospective study in nine patients over a period of 8 years extending from 2000 to 2008, collated in the Department of Physical Medicine and Functional Rehabilitation, CHU Sahloul, Sousse, Tunisia.ResultsThe mean age of our patients was 43.8 years; sex ratio was 5/4. The spine involvement of tuberculosis was dorsal in seven cases, dorso-lumbar in one patient, and multiple (cervical, dorsal and lumbar) in one case. All patients were paraplegic with a neurological involvement of the bladder. They had prior antituberculosis chemotherapy for at least 8 months. Decompression surgery was performed in six cases. Two female patients presented disorders of spinal posture during treatment requiring surgical revision with osteosynthesis. All patients received additional rehabilitation care. Following a mean duration of hospitalisation in the Rehabilitation department of 47 days with twice-daily sessions of tailored physiotherapy, three patients remained in complete paraplegia, autonomous in wheel-chair and with vesical and sphincter incontinence. The measure of functional independence (MFI) was at admission/discharge 71/92.ConclusionRehabilitation takes an important place in the medico-surgical management in Pott's disease, to limite or compensate the disabilities and handicap related to this pathology

Modélisation micromécanique de l'effet de taille de grains sur le comportement mécanique de matériaux biphasés viscoplastiques

Les méthodes d'homogénéisation basées sur le problème de l'inclusion d'Eshelby (1957), tiennent compte du comportement local, de la fraction volumique et de la morphologie des différents constituants du matériau mais souffrent d'une absence de description de longueurs internes (taille de grain par exemple). Cet article propose une nouvelle approche micromécanique basée sur une représentation du grain par une inclusion constituée d'une zone intérieure sphérique plastiquement uniforme entourée d'une couche extérieure sphérique, épousant le joint de grain, d'épaisseur donnée et de fraction volumique dépendant par construction de la taille de grain. L'ensemble est noyé dans un milieu homogène dont les propriétés dépendent des équations constitutives de l'intérieur et de la couche de l'inclusion et de leurs fractions volumiques respectives. La couche dans laquelle évolue à la fois des dislocations géométriquement nécessaires et des dislocations stockées, représente la zone affectée par le gradient de déformation plastique entre l'inclusion et le milieu homogène

EFFECTS OF MAGHNITE NANOCLAY MODIFICATION AND COMPATIBILIZATION ON THE PHYSICAL AND MORPHOLOGICAL PROPERTIES OF POLY(VINYL CHLORIDE)/POLY(ETHYLENE-CO-VINYL ACETATE) BLENDS

In this research work poly(vinyl chloride)(PVC), ethylene vinyl acetate copolymer (EVA), and Maghnite nanoclay (MGT) were used to prepare PVC/EVA nanocomposites. The MGT clay was intercalated with octadecyltrimethylammonium chloride (ODTMA) and grafted with                 γ-aminopropyltriethoxysilane (APTES). The blend nanocomposites were prepared through the melt mixing of PVC/EVA blend at a weight ratio of 50/50 (wt%/wt%) with 20 wt% of compatibilizer; ethylene vinyl acetate grafted with an alcohol (EVA-g-OH) and 3 wt% of modified MGT clay using a Brabender plastograph. The nanocomposites so prepared were characterized using X-ray diffraction, TGA/DTA, mechanical tests and SEM. The results showed that when PVC was blended with EVA, with the modified MGT and with the compatibilizer, synergistic effects in the thermal stability and mechanical properties were observed

Producing Enactable Protocols in Artificial Agent Societies

This paper draws upon our previous work [7, 16] in which we proposed the organisation of services around the concept of artificial agent societies and presented a framework for representing roles and protocols using LTSs. The agent would apply for a role in the society, which would result in its participation in a number of protocols. We advocated the use of the games-based metaphor for describing the protocols and presented a framework for assessing the admission of the agent to the society on the basis of its competence. In this work we look at the subsequent question: what information should the agent receive upon entry?. We can not provide it with the full protocol because of security and overload issues. Therefore, we choose to only provide the actions pertinent to the protocols that the role the agent applied for participates in the society. We employ branching bisimulation for producing a protocol equivalent to the original one with all actions not involving the role translated into silent (τ) actions. However, this approach sometimes results in non-enactable protocols. In this case, we need to repair the protocol by adding the role in question as a recipient to certain protocol messages that were causing the problems. We present three different approaches for repairing protocols, depending on the number of messages from the original protocol they modify. The modified protocol is adopted as the final one and the agent is given the role automaton that is derived from the branching bisimulation process

Management of emerging multidrug-resistant tuberculosis in a low-prevalence setting

AbstractMultidrug-resistant (MDR) tuberculosis (TB) is an emerging concern in communities with a low TB prevalence and a high standard of public health. Twenty-three consecutive adult MDR TB patients who were treated at our institution between 2007 and 2013 were reviewed for demographic characteristics and anti-TB treatment management, which included surgical procedures and long-term patient follow-up. This report of our experience emphasizes the need for an individualized approach as MDR TB brings mycobacterial disease management to a higher level of expertise, and for a balance to be found between international current guidelines and patient-tailored treatment strategies

Evidence of the contribution of the X chromosome to systemic sclerosis susceptibility: Association with the functional IRAK1 196Phe/532Ser haplotype

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Comparison of the effects of salmeterol/fluticasone propionate with fluticasone propionate on airway physiology in adults with mild persistent asthma

<p>Abstract</p> <p>Background</p> <p>This study compared the effect of inhaled fluticasone propionate (FP) with the combination of salmeterol/fluticasone propionate (SFC) on lung function parameters in patients with mild asthma.</p> <p>Methods</p> <p>Adult patients with mild persistent asthma (≥ 80% predicted FEV₁) receiving 200–500 μg of BDP or equivalent were randomised to receive either FP 100 μg or SFC 50/100 μg twice daily from a Diskus^®inhaler for four weeks. The primary outcome was the change from baseline in airway resistance (sRaw) at 12 hrs post dose measured by whole body plethysmography. Impulse oscillometry and spirometry were also performed.</p> <p>Results</p> <p>A comparison of the geometric mean sRaw at 12 hrs post dose in the SFC group to the FP group gave a ratio of 0.76 (0.66 – 0.89, p < 0.001) at week 2 and 0.81 (0.71 – 0.94, p = 0.006) at week 4. Similarly, significant results in favour of SFC for oscillometry measurements of resistance and reactance were observed. FEV₁was also significantly superior at week 2 in the SFC group (mean difference 0.16L, 95% CI; 0.03 – 0.28, p = 0.015), but not at week 4 (mean difference 0.17L, 95% CI -0.01 – 0.34, p = 0.060).</p> <p>Conclusion</p> <p>SFC is superior to FP in reducing airway resistance in mild asthmatics with near normal FEV₁values. This study provides evidence that changes in pulmonary function in patients with mild asthma are detected more sensitively by plethysmography compared to spirometry</p> <p>Trial registration number</p> <p>NCT00370591.</p

Characterization of a K+-induced conformational switch in a human telomeric DNA oligonucleotide using 2-aminopurine fluorescence

Human telomeric DNA consists of tandem repeats of the DNA sequence d(GGGTTA). Oligodeoxynucletotide telomere models such as d[A(GGGTTA)(3)GGG] (Tel22) fold in a cation-dependent manner into quadruplex structures consisting of stacked G-quartets linked by d(TTA) loops. NMR has shown that in Na(+) solutions Tel22 forms a ‘basket’ topology of four antiparallel strands; in contrast, Tel22 in K(+) solutions consists of a mixture of unknown topologies. Our previous studies on the mechanism of folding of Tel22 and similar telomere analogs utilized changes in UV absorption between 270 and 325 nm that report primarily on G-quartet formation and stacking showed that quadruplex formation occurs within milliseconds upon mixing with an appropriate cation. In the current study, we assessed the dynamics and equilibria of folding of specific loops by using Tel22 derivatives in which the dA residues were serially substituted with the fluorescent reporter base, 2-aminopurine (2-AP). Tel22 folding induced by Na(+) or K(+) assessed by changes in 2-AP fluorescence consists of at least three kinetic steps with time constants spanning a range of ms to several hundred seconds. Na(+)-dependent equilibrium titrations of Tel22 folding could be approximated as a cooperative two-state process. In contrast, K(+)-dependent folding curves were biphasic, revealing that different conformational ensembles are present in 1 mM and 30 mM K(+). This conclusion was confirmed by (1)H NMR. Molecular dynamics simulations revealed a K(+) binding pocket in Tel22 located near dA1 that is specific for the so-called hybrid-1 conformation in which strand 1 is in a parallel arrangement. The possible presence of this topologically specific binding site suggests that K(+) may play an allosteric role in regulating telomere conformation and function by modulating quadruplex tertiary structure