A numerical method is presented to determine the steady-state nonlinear response of a rotor-support system due to deadband and rubbing using discrete Fourier transformation and inverse discrete Fourier transformation. Damaging subharmonic and superharmonic responses are found to occur in presence of a side force. The calculated results agree with the general trends which have been observed experimentally by other investigators. The effects of selected nondimensionalized parameters on rotor response are studied.

Background: Successful adaptation of refugees to a new society can be hindered by traumatic experiences and psychiatric symptoms. This study aims to examine the relationship between trauma, psychiatric symptoms and life satisfaction of North Korean refugees resettled in South Korea. Methods: A total of 211 North Korean refugees living in South Korea completed a series of questionnaires on the history of their previous traumatic experiences, life satisfaction in South Korea, depression, anxiety, somatization and post-traumatic stress disorder (PTSD) symptoms. Results: North Korean refugees who had experienced more traumatic events were less satisfied with their economic status in South Korea. Severe depression, anxiety, somatization or PTSD symptoms negatively correlated with their overall satisfaction in South Korea. In the stepwise regression model including all psychiatric symptoms and the number of traumatic experiences as dependent variables, only anxiety, but not trauma, predicted lower life satisfaction in South Korea. Conclusions: Traumatic experiences of North Korean refugees negatively affected the life satisfaction, especially the economic satisfaction, in South Korea. Since the negative effect of trauma was mainly mediated by psychiatric symptoms, the strategy of relieving psychiatric symptoms of traumatized refugees may help the adaptation of refugees.

Implantable electronics have recently been attracting attention because of the promising advances in personalized healthcare. They can be used to diagnose and treat chronic diseases by monitoring and applying bioelectrical signals to various organs. However, there are challenges regarding the rigidity and hardness of typical electronic devices that can trigger inflammatory reactions in tissues. In an effort to improve the physicochemical properties of conventional implantable electronics, soft hydrogel-based platforms have emerged as components of implantable electronics. It is important that they meet functional criteria, such as stretchability, biocompatibility, and self-healing. Herein, plant-inspired conductive alginate hydrogels composed of “boronic acid modified alginate” and “oligomerized epigallocatechin gallate,” which are extracted from plant compounds, are proposed. The conductive hydrogels show great stretchability up to 500% and self-healing properties because of the boronic acid-cis-diol dynamic covalent bonds. In addition, as a simple strategy to increase the electrical conductivity of the hydrogels, ionically crosslinked shells with cations (e.g., sodium) were generated on the hydrogel under physiological salt conditions. This decreased the resistance of the conductive hydrogel down to 900 ohm without trading off the original properties of stretchability and self-healing. The hydrogels were used for “electrophysiological bridging” to transfer electromyographic signals in an ex vivo muscle defect model, showing a great bridging effect comparable to that of a muscle-to-muscle contact model. The use of plant-inspired ionically conductive hydrogels is a promising strategy for designing implantable and self-healable bioelectronics.

The forced steady response of a single degree of freedom system involving a large non-linearity, represented by unsymmetric piccewise•linear stiffness, is determined by a harmonic balance Newton-Raphson method with the application of the fast Fourier transformation (FFT) algorithm. All possible subharmonic, harmonic, and superharmonic responses arc sought. The responses of two systems involving subharmonic and superharmonic dominant motions are calculated by the newly developed method and compared with previously published findings. The results obtained by using this method reveal the details of the response of the systems more efficiently than previous methods.