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IntroductionDespite popular speculation that nostalgic social media use skyrocketed during the COVID-19 pandemic, this has yet to be formally investigated in the scientific literature.MethodsInterrupted time series analysis (ITSA) using a segmented regression model was performed to examine the changes in the weekly volume of searches for nostalgic songs on Douyin (the Chinese version of TikTok), as a proxy for nostalgic social media use, before and after the lockdown of Wuhan (signaled the start of the pandemic on a national scale in China).ResultsAcross the study period (January 1, 2019–February 28, 2021), an immediate and significant increase in nostalgic social media use was observed when the pandemic initially started (95% CI = [47314.30, 154969.60], p

IntroductionPrevious studies have found a causal relationship between scarcity and the adverse impact it has on executive functioning. However, few studies have directly examined perceived scarcity, and cognitive flexibility (the third component of executive functions) has rarely been included.MethodsUsing a 2 (group: scarcity group vs. control group) × 2 (trial type: repeat trial vs. switch trial) mixed design, this study directly explored perceived scarcity’s impact on cognitive flexibility and revealed its neural basis in the switching tasks. Seventy college students participated in this study through open recruitment in China. A priming task was used to induce perceived scarcity, thus exploring the impact of perceived scarcity on participants’ performance in switching tasks and enabling the analysis of the neural activity of the brain, combined with electroencephalograph (EEG) technology.ResultsIn terms of behavioral outcomes, perceived scarcity led to poorer performance and a greater switching cost of reaction time in the switching tasks. Regarding neural activity, perceived scarcity led to an increase in the amplitude of P3 differential wave (repeat trials minus switch trials) in the parietal cortex during the target-locked epochs in the switching tasks.DiscussionPerceived scarcity can lead to changes in the neural activity of the brain regions related to executive functioning, resulting in a temporary decrease in cognitive flexibility. It may lead to individuals unable to adapt well to the changing environment, unable to quickly devote themselves to new tasks, and reduce work and learning efficiency in daily life.

BackgroundThe emergence of the COVID-19 pandemic has created an environment in which numerous determinants of poor mental health are intensified. Lockdown, re-lockdown, and media coverage of the spread of the virus, have the potential to contribute to increased levels of anxiety and depression. Mindfulness may act as a buffer against COVID-19-related depressive and anxiety disorders.MethodsWe conducted a systematic review and meta-analysis by searching PubMed, PsycINFO, Web of Science, and Google Scholar for any study published between January 2020 and March 2022. In this study, Comprehensive Meta-Analysis Version 3.3 software was applied to evaluate the effect size by random effect model. In addition, the heterogeneity analysis was evaluated using indicators Q and I2 indicators. Three methods were used to test for publication bias: funnel plot, Classic Fail-safe N, and Egger’s linear regression. According to the features of the included articles, subgroup analysis was utilized for the moderator analysis of this study.ResultsThe analysis finally included 12 articles (16 samples, N = 10,940) and obtained 26 independent effect sizes. In accordance with the meta-analysis, in the random effect model, the correlation between mindfulness and anxiety was −0.330 (p

In the time of the COVID-19 pandemic, people are often faced with uncertain risky choice. Risky choice will be affected by different descriptions of the event’s gain or loss framework, this phenomenon is known as the framing effect. With the continuous expansion and in-depth study of frame effects in the field of risky choice, researchers have found that the are quite different in different situations. People have different interpretations of the same event at different psychological distances, and will also be affected by their own emotions. Therefore, the current study examines the common influence of task frame, spatial distance, and trait emotion on risky choice through two studies. Study 1 used a 2 (framework: gain vs. loss) × 2 (trait sentiment: high vs. low) inter-subject design, and the dependent variable is the choice of the rescue plan for the classic “Asian disease” problem. The results revealed that trait anger did not predict individuals’ risky choice preferences, and high trait anxiety led individuals to be more risk-averse. The framing effect exists in risky choice, and individuals prefer risk seeking in the loss frame. Study 2 used a 2 (spatial distance: distant vs. proximal) × 2 (framework: gain vs. loss) × 2 (trait sentiment: high vs. low) three-factor inter-subject design in which the dependent variable is the choice of rescue plan. The results indicate that the framing effect also exists in risky choice, and individuals prefer risk seeking in a loss frame. High trait anxiety lead individuals to be more risk-averse, while trait anger has no significant predictive effect on risk preference. Distant spatial distance lead individuals to increase their preference for risk-seeking under the gain frame, which leads to the disappearance of the framing effect. In conclusion, trait anxiety and spatial distance have a certain degree of influence on risky choice under the framework of gain and loss.

ObjectIn this study, we aimed to explore the influences of stress responses and negative emotion on mental health of college students during the initial COVID-19 outbreak in China.MethodsA nationally representative sample of 1,351 college students, aged 18–23 years, took part in an online survey during the COVID-19 outbreak. The ANOVA, correlation coefficients, structural equation modeling (path analysis), and other statistical analysis methods were used for data analysis.Results(1) The Chinese college students' epidemic panic and cognitive evaluation were found to be moderate (3.73 ± 0.74, 3.76 ± 0.62), while their defensive response was higher (4.61 ± 0.55). Their mental health during the COVID-19 outbreak was found to be good (3.75 ± 0.76). (2) The quality of their mental health was significantly and negatively associated with epidemic panic, and the quality of their mental health was significantly and positively associated with defensive response. (3) The quality of their mental health was significantly and negatively associated with negative emotion. (4) College students' epidemic panic and defensive response to the COVID-19 had a directly predictive effect on their mental health.ConclusionCollege students' negative emotion played a partial mediating role in the relationship between epidemic panic and mental health. College students' negative emotion played a complete mediating role in the relationship between cognitive appraisal and mental health.

ObjectIn this study, we aimed to explore the influences of pandemic stress, risk perception, and coping efficacy on the mental health of Chinese college students during the COVID-19 pandemic.MethodsA nationally representative sample of Chinese college students (N = 3,381, Mage = 20.85, SDage = 1.31) took part in an online survey during the COVID-19 pandemic. Correlation coefficients, structural equation modeling, and other statistical analysis methods were used for data analysis.Results(1) The Chinese college students' pandemic stress and perceived pandemic risk were found to be moderate (3.51 ± 0.83, 3.45 ± 0.94), whereas their perceived infection risk was lower (2.10 ± 0.67). Their mental health during the COVID-19 pandemic was found to be good (3.80 ± 0.73). (2) The quality of their mental health was significantly and negatively associated with pandemic stress, perceived pandemic risk, and perceived infection risk. The level of their mental health was significantly and positively associated with coping efficacy, and their coping efficacy was significantly and negatively associated with pandemic stress, perceived pandemic risk, and perceived infection risk.ConclusionCoping efficacy played a partial mediating role in the relationship between pandemic stress and mental health, coping efficacy played a partial mediating role in the relationship between perceived infection risk and mental health, and coping efficacy played a complete mediating role in the relationship between perceived pandemic risk and mental health. Our findings show the importance of fostering college students' coping efficacy to improve their mental health during the COVID-19 pandemic.

Based on the nonequilibrium Green’s function (NEGF), we develop a quantum nonlinear theory to study time-dependent ac transport properties in the low frequency and nonlinear bias voltage regimes. By expanding NEGF in terms of time to the linear order in Wigner representation, we can explicitly include the time-dependent self-consistent Coulomb interaction induced by external ac bias. Hence this theory automatically satisfies two basic requirements, i.e. current conservation and gauge invariance. Within this theory, the nonlinear ac current can be evaluated at arbitrarily large bias voltages under the low frequency limit. In addition, we obtain the expression of time-dependent current under the wide band limit and derive the relation between the nonlinear electrochemical capacitance and the bias voltage, which are very useful in predicting the dynamical properties of nanoelectronic devices. This quantum theory can be directly combined with density functional theory to investigate time-dependent ac transport from first-principles calculation.

Using the nonequilibrium Green’s function combined with the density functional theory, we investigate the spin-resolved photoelectric current in ferromagnetic hydrogenated zigzag graphene nanoribbons with boron or phosphorus atom substitutions (B/P-ZGNRs). Our findings indicate that B/P substitution induces half-metallic or semiconducting characteristics, depending on the edge form and substituted atoms. Induced by linear polarized light, the spin-resolved photocurrent could reveal information of the band structure and the contribution of different orbitals to the transport processes. Photocurrent peaks at specific photon energies clearly indicate the band edge of B/P-ZGNRs, while its signs reflect the distribution of the transmission coefficient spectrum. In symmetrically hydrogenated B/P-ZGNRs, the p _x orbital is found to be dominant. However, in asymmetric B/P-ZGNRs, the p _y orbital can also be dominant. Furthermore, B/P substitution induces a narrow band near the Fermi level, leading to remarkable negative differential resistance. These findings suggest potential applications of B/P-ZGNRs in spintronic devices and micro photoelectric detection.

Monolayer ${\mathrm{MoS}}_2$ is a typical valleytronic material with valley-spin locked valence bands. We numerically investigate the valley-spin polarized current in monolayer ${\mathrm{MoS}}_2$ via adiabatic electron pumping. By introducing an exchange field to break the energy degeneracy of monolayer ${\mathrm{MoS}}_2$ , the top of its valence bands is valley-spin polarized and tunable by the exchange field. A device with spin-up polarized left lead, spin-down polarized right lead, and untuned central region is constructed through applying different exchange fields in the corresponding regions. Then, equal amount of pumped currents with opposite valley-spin polarization are simultaneously generated in the left and right leads when periodically varying two pumping potentials. Numerical results show that the phase difference between the pumping potentials can change the direction and hence polarization of the pumped currents. It is found that the pumped current exhibits resonant behavior in the valley-spin locked energy window, which depends strongly on the system size and is enhanced to resonant current peaks at certain system lengths. More importantly, the pumped current periodically oscillates as a function of the system length, which is closely related to the oscillation of transmission. The effects of other system parameters, such as the pumping amplitude and the static potential, are also thoroughly discussed.