Identification of initial severity determinants to predict arthritis after chikungunya infection in a cohort of French gendarmes.

BACKGROUND: The objective was to identify severity characteristics of initial chikungunya infection (CHIKV) stages associated with post-CHIKV arthritis and arthralgia. METHODS: French gendarmes exposed to the 2005-2006 CHIKV epidemic in Reunion Island who completed the 2006 (self-reporting acute and early chronic [median: 6 months] symptoms) and 2008 (Endpoint [median: 30 months]: self-perceived recovery and rheumatic disorders (RDs)) surveys were included. Multinomial logistic regression and multiple correspondence analysis (MCA) were used. Arthralgia was defined by joint pain and/or stiffness and arthritis by joint swelling in addition to pain and/or stiffness. RESULTS: In 2008, 124 (31.3%)/403 participants (101 CHIKV+/302 CHIKV-) reported arthralgia and 57 (14.1%) arthritis. The multivariate model kept CHIKV infection, comorbidity and acute stage depressed mood as independent prognostic factors for both arthralgia and arthritis, but found early chronic stage RD as the main determinant of the same RD two years later.The MCA performed with the 85 CHIKV + patients who answered the question on self-perceived recovery enabled the calculation of severity scores based on initial symptoms that were strongly associated with persistent arthritis and, to a lesser extent, to arthralgia in bivariate analyses. The MCA graph clearly distinguished arthritis as the only RD associated with early severity indicators represented by sick leave, joint swelling and depressed mood during the acute stage, and early chronification of arthritis and depressed mood. CONCLUSION: Initial CHIKV severity predicted recovery, with higher severity associated with arthritis and lower severity with arthralgia. More interestingly, specific markers of post-CHIKV arthritis, which can easily be used by clinicians for case management, were identified.

Enhanced Power Generation by Piezoelectric P(VDF-TrFE)/rGO Nanocomposite Thin Film.

In this study we fabricated a piezoelectric nanogenerator (PENG) of nanocomposite thin film comprising a conductive nanofiller of reduced graphene oxide (rGO) dispersed in a poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) matrix that was anticipated to show enhanced energy harvest performance. For the film preparation we employed the Langmuir-Schaefer (LS) technique to provide direct nucleation of the polar ß-phase without any traditional polling or annealing process. We prepared five PENGs consisting of the nanocomposite LS films with different rGO contents in the P(VDF-TrFE) matrix and optimized their energy harvest performance. We found that the rGO-0.002 wt% film yielded the highest peak-peak open-circuit voltage (VOC) of 88 V upon bending and releasing at 2.5 Hz frequency, which was more than two times higher than the pristine P(VDF-TrFE) film. This optimized performance was explained by increased ß-phase content, crystallinity, and piezoelectric modulus, and improved dielectric properties, based on scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), x-ray diffraction (XRD), piezoelectric modulus, and dielectric property measurement results. This PENG with enhanced energy harvest performance has great potential in practical applications for low energy power supply in microelectronics such as wearable devices.

Nonlinear adaptive control of magnetic levitation system using terminal sliding mode and integral backstepping sliding mode controllers.

Magnetic levitation (MagLev) system is an unstable, highly non-linear and dynamically fast. These characteristics make it challenging task to design a suitable controller to ensure any object to stay at a certain distance from the electromagnet with negligible error. It can be achieved by generating the required flux with the help of a control input. This suspension of ferromagnetic object in air is achieved by balancing the forces of attraction of gravity and electromagnetic. This makes the system highly vulnerable to external disturbances and parametric uncertainties. The controller must be able to adapt the changing electrical resistance and be robust if the mass of the levitating object for MagLev changes. In this paper, three nonlinear controllers: adaptive terminal sliding mode control (AT-SMC), adaptive backstepping sliding mode (ABS-SMC) and adaptive integral backstepping sliding mode (AIBS-SMC) based controllers have been proposed for tracking the air gap to desired value while maintaining the momentum and flux to desired values. Lyapunov theory has been used for proving the global asymptotic stability of the proposed controllers. For performance analysis, simulations have been carried out using Matlab/Simulink environment, where the proposed controllers have been compared with each other. Among the proposed controllers, AT-SMC gives better performance in terms of transient and overall dynamical response. The effect of parametric variations/uncertainties on all of the proposed controllers has also been examined by varying parametric values, by adding noise and disturbance in the system. Moreover, simulation results for the proposed controllers have also been compared with recently proposed controllers in literature. The physical realization of proposed AT-SMC has been examined with the help of a comparison between simulation results and the controller hardware in loop (C-HIL) experimental results.