Buckling of a compliant hollow cylinder attached to a rotating rigid shaft

International audienceBifurcations in the equilibrium shape of a thick elastic layer attached to a circular rigid cylinder rotating about its axis are investigated analytically and numerically. The centrifugal force breaks the symmetry of the system leading to deformations invariant along the axis as the result of an instability. The instability threshold depends at linear order on the relative thickness of the compliant layer, and on a dimensionless control parameter based on the elastic modulus, the angular velocity and the outer radius. A weakly non linear analysis, carried out for layers following the Mooney-Rivlin constitutive law, points out the discon-tinuous (sub-critical) features of the bifurcation, except for relative thickness laying in a very narrow range in which the bifurcation is super-critical. Numerical simulations in the fully post-buckled regime yield the absolute instability threshold, and the order in the rotational symmetry of the developed equilibrium shape

VIRTUAL REALITY & SPORT

This applied session deals with the design of immersive environments for human motion performance analysis. In a first part of the session, a theoretical presentation describes the aims and scopes of such type of experiments. In a second part of the session, a review of the available immersive systems will be exposed. Finally, a practical framework will be designed in real-time with the attendees: a low-cost immersive environment based on a Microsoft Kinect, a Razer Hydra and an Oculus Rift Head Mounted Display device. We will develop an experiment to analyse perception-action coupling in soccer with simulated virtual opponents enabling to analyse the decision-making of a real goalkeeper

Consumer perceptions of place-based foods, food chain profit distribution, and family farms

Consumers were asked for their views on a variety of alternative marketing scenarios for food products; the scenario responses offer guidance for producers seeking new ways to position their products

Cartilaginous tibial eminence fractures in children: which recommendations for management of this new entity ?

PURPOSE: Cartilaginous tibial eminence fracture (CTEF) is a new pattern of ACL rupture in children under the age of nine. MRI signs have been recently reported, but no series gave information about outcomes. It was hypothesized that primary treatment gave better results than delayed management due to frequent misdiagnosis. METHOD: This retrospective study focused on 15 patients, managed acutely (n = 7) or delayed (n = 8). The patients' median age at the time of initial injury was 6.5 years (range 5-9). Lysholm, IKDC 2000 subjective scores, and the measurement of the residual laxity by a side-to-side difference with a KT-1000 junior arthrometer were used at the time of revision. RESULTS: After a mean follow-up of 9.8 years (range 1-18.5), the mean Lysholm and IKDC subjective scores were, respectively, 97.7 ± 2.6 and 97 ± 3.4. The median residual laxity was 2 mm (range 0-4). Non-operative treatment lead to 2 failures: intermeniscal ligament entrapment and combined avulsion fracture at the femoral site. Suture fixation of the avulsed fragment allows regularly good results when performed acutely or even 4 years after the injury. The hypothesis that primary treatment gives better result than delayed treatment tends to be wrong as 2 failures were reported in each group. An ACL reconstruction was performed in 3 out of the 4 treatment failures. Progressive resorption of the avulsed fragment was noticed in 3 of the 4 failures suggesting an associated ACL resorption. CONCLUSION: CTEF has a good prognosis even after misdiagnosis and treatment at the time of non-union; this could be due to low-energy mechanism of injury and low rate of associated lesion. Orthopaedic treatment for acute minimally displaced fractures is only indicated under strict MRI control, and suture fixation is the recommended strategy in other situations. Conservative management of non-union could expose to ACL involution and cannot be recommended. LEVEL OF EVIDENCE: Retrospective case series, Level IV

KINEMATIC ANALYSIS OF HANDBALL THROWING

Kinematic analysis of handball throwing is not well documented. If we know that the studies on the other throwing activities can give us important data, we have to develop the study of handball throwing in order to understand this special motion better. It appears that handball throwing is similar to football passing except for the special upper arm external rotation. Indeed, the maximal upper arm external rotation is minor to those noted in baseball pitching or football passing. Moreover, the upper arm is internally rotated at the ball release. If the common ball weight can explain the resemblance between football passing and handball throwing, the specific humeral rotation can result from some technical lacks of our players or from a specific adaptation to avoid a great external humeral rotation recognized as traumatizing for the arm

Superior Protection against Malaria and Melanoma Metastases by a C-glycoside Analogue of the Natural Killer T Cell Ligand α-Galactosylceramide

α-Galactosylceramide (α-GalCer) is a glycolipid that stimulates natural killer T cells to produce both T helper (Th) 1 and Th2 cytokines. This property enables α-GalCer to ameliorate a wide variety of infectious, neoplastic, and autoimmune diseases; however, its effectiveness against any one disease is limited by the opposing activities of the induced Th1 and Th2 cytokines. Here, we report that a synthetic C-glycoside analogue of α-GalCer, α-C-galactosylceramide (α-C-GalCer), acts as natural killer T cell ligand in vivo, and stimulates an enhanced Th1-type response in mice. In two disease models requiring Th1-type responses for control, namely malaria and melanoma metastases, α-C-GalCer exhibited a 1,000-fold more potent antimalaria activity and a 100-fold more potent antimetastatic activity than α-GalCer. Moreover, α-C-GalCer consistently stimulated prolonged production of the Th1 cytokines interferon-γ and interleukin (IL)-12, and decreased production of the Th2 cytokine IL-4 compared with α-GalCer. Finally, α-C-GalCer's enhanced therapeutic activity required the presence of IL-12, which was needed to stimulate natural killer cells for optimal interferon-γ production, but did not affect IL-4. Overall, our results suggest that α-C-GalCer may one day be an excellent therapeutic option for diseases resolved by Th1-type responses