High-frequency oscillations have been frequently observed under the conditions of tearing modes and runaway electrons in J-TEXT Ohmic plasmas. It is found the frequencies of these oscillations range from 20 to 45 kHz, being consistent with the beta-induced Alfvén Eigenmodes (BAEs) with the same order of the low-frequency gap induced by finite beta effects and the coupling of the shear Alfvén wave with the compressional response of the plasma. The exciting conditions for BAEs are investigated, which indicate that runaway electrons, as well as magnetic perturbations contributed by magnetic islands, are indispensable in the excitation of BAEs. In addition, externally applied static resonant magnetic perturbations (RMPs) are used to excite BAEs successfully for the first time in J-TEXT, as indicated by high frequency oscillations (~30 kHz). Further studies show that BAEs can be excited only when the coil current of RMP is stronger than 4 kA, and the strength of BAEs becomes stronger with stronger RMP. To assess the verification of the BAEs, the frequencies of observed modes are compared to the calculated frequencies of the BAE frequency gap in the Alfvén continuum, namely the continuum accumulation point (CAP), and they are found to be close.

Investigations of beta-induced Alfvén eigenmodes (BAEs) destabilized by resonant magnetic perturbations (RMPs) have been conducted on the J-TEXT tokamak. In the Ohmic discharges, with RMPs having finite perturbed amplitudes, two different types of Alfvén eigenmodes have been observed and identified. One is considered as m-BAE, due to the strong correlation with magnetic island in some noticeable aspects, for example, frequency characteristic, mode number and driving mechanism. Specifically, the standing wave nodes of m-BAE are located at the O point and X point of the magnetic island. Another one is discerned as the magnetic island-induced AE (labeled as the MIAE-like mode in this work), which is consistent with the prediction of theory (Biancalani et al 2010 Phys. Rev. Lett. 105 095002). The frequency of MIAE-like mode is found to be approximately proportional to the square of magnetic island width.

The 2019 coronavirus disease (COVID-19) has spread to the whole world. Psychological and sleep problems among confirmed patients have drawn extensive attention which may be highly related to immune function and inflammatory responses of people. The aim of this study is to examine the correlation of mental health status, sleep quality, and inflammatory markers, virus negative conversion time (NCT) among confirmed patients during the COVID-19 outbreak. A cross-sectional survey was conducted in this study. Data from 66 patients assessed with demographic information, anxious symptom, depressive symptom, stress, and sleep quality were collected using a smartphone-based questionnaire platform and then clinical characteristics and laboratory indicators were collected using case review. Nearly 30% of the participants reported depression, anxiety, perceived pressure, and poor sleep quality. Compared with the group without depression, neutrophil count, and ratio of neutrophil count to lymphocyte count (NLR) in the depression disorder group were increased ( P = .028, 0.043). There was also a significant difference in NLR and NCT between the anxiety group and the non-anxiety group ( P = .021, .024). Similarly, compared with the good sleep quality group, NLR in the poor sleep quality group was increased ( P = .011). Correlation analysis indicated that Self-Rating Depression Scale score was positively related to neutrophil count and NLR ( r = 0.366, 0.330, P = .016, .031). The total score of Pittsburgh Sleep Quality Index (PSQI) was negatively related to lymphocyte count ( r = −0.317, P = .049), and the sleep disturbance as 1 of the 7 dimensions of PSQI scale was positively correlated with NCT and NLR ( r = 0.370, 0.340, P = .020, .034). In our study, confirmed patients were prone to have psychological and sleep problems. The level of inflammation in patients with psychological and sleep problems was higher than that in patients without corresponding problems. The inflammatory level increased with the increase of Self-Rating Depression Scale score, and the lymphocyte count decreased with the increase of the PSQI score. NCT was prolonged in the anxiety group and sleep disturbance was positively correlated with NCT.