The chain mediating roles of anxiety and depression in the relationship between the effects of the COVID-19 pandemic and procrastination in adolescents: a longitudinal study.

BACKGROUND: The relationship between the Coronavirus Disease 2019 (COVID-19) pandemic, which is a traumatic event for adolescents, and procrastination is not clear. Mental health may play an important role in this relationship; however, the underlying mechanisms remain unknown. This study aimed to construct chain mediation models to examine whether anxiety and depression symptoms mediate the effects of the COVID-19 pandemic on procrastination in adolescents. METHODS: A convenience sample of 12 middle and high schools in Harbin, China, with four follow-up online surveys was conducted during the COVID-19 pandemic. A total of 4,156 Chinese adolescents were enrolled in this study, of whom ages 11-18 (Mean = 13.55; SD = 1.18), 50.75% were male, and 93.24% were middle school students. Descriptive demographic analysis and Pearson's correlation analysis of the effects of the COVID-19 pandemic (T1), anxiety(T2), depression (T3), and procrastination (T4) were performed in SPSS 22.0. Chain mediation analysis performed with Mplus 8.3. RESULTS: The effects of the COVID-19 pandemic, anxiety symptoms, depression symptoms, and procrastination were positively correlated (P < 0.01). The effects of the COVID-19 pandemic have a direct link on adolescent procrastination (effect = 0.156; SE = 0.031; 95%CI: 0.092, 0.214), and have three indirect paths on procrastination: the independent mediating role of anxiety symptoms was 29.01% (effect = 0.047; SE = 0.012; 95%CI: 0.024, 0.072), the independent mediating role of depression symptoms was 29.01% (effect = 0.047; SE = 0.010; 95%CI: 0.030, 0.068), as well as the completely chain mediating role of anxiety and depression symptoms was 15.43% (effect = 0.025; SE = 0.005; 95%CI: 0.017, 0.036). CONCLUSIONS: Our results suggest that anxiety and depressive symptoms are part of a causal chain between the effects of the COVID-19 pandemic and procrastination among Chinese adolescents. To effectively reduce their procrastination, attention should be paid to the emotional distress caused to adolescents by major events such as the COVID-19 epidemic. All data were taken from self-reported measures and one city in China, which may bias the results and limit their generalizability.

Disorder- and Topology-Enhanced Fully Spin-Polarized Currents in Nodal Chain Spin-Gapless Semimetals.

Recently discovered high-quality nodal chain spin-gapless semimetals MF_{3} (M=Pd, Mn) feature an ultraclean nodal chain in the spin up channel residing right at the Fermi level and displaying a large spin gap leading to a 100% spin polarization of transport properties. Here, we investigate both intrinsic and extrinsic contributions to anomalous and spin transport in this class of materials. The dominant intrinsic origin is found to originate entirely from the gapped nodal chains without the entanglement of any other trivial bands. The side-jump mechanism is predicted to be negligibly small, but intrinsic skew scattering enhances the intrinsic Hall and Nernst signals significantly, leading to large values of respective conductivities. Our findings open a new material platform for exploring strong anomalous and spin transport properties in magnetic topological semimetals.

Negative emotions, self-care activities on glycemic control in adults with type 2 diabetes: a cross-sectional study.

Glycemic control has become a focus of concern among diabetic patients. However, only 26.71% of patients achieved better glycemic control in China. Given the complexity of glycemic control, it is worth investigating the potential mechanisms between negative emotions and glycemic control. A total of 428 participants were recruited from a tertiary hospital (the number of hospital beds>500). They completed questionnaires consisting of demographics, Zung Self-Assessed Anxiety Scale(SAS), Zung Self-Assessed Depression Scale(SDS), and the Summary of Diabetes Self-Care Activities (SDSCA). HbA1 c was used to measure glycemic control. Descriptive analysis, Pearson correlation analysis, and Bootstrap analysis were conducted to analyze data. A total of 428 questionnaires were distributed, with 28 invalid questionnaires (93.46% were valid). Depression and self-care activities (exercise, medication) were associated with glycemic control. At the same time, the Bootstrap analysis revealed that self-care activities (exercise: standardized coefficient ß = 0.0181, p < 0.05, medication: standardized coefficient ß = 0.0211, p < 0.05) mediated the relationship between depression and glycemic control.

Pressure induced excellent thermoelectric behavior in skutterudites CoSb3 and IrSb3.

Utilizing the first-principle calculations combined with Boltzmann transport equation (BTE) and semiclassical analysis, we have systematically investigated the electronic structure, lattice thermal conductivity κL, Seebeck coefficient S, and the dimensionless figure of merit zT as a function of hydrostatic pressure P in crystalline skutterudites CoSb3 and IrSb3. Interestingly, as the pressure increases, the band gap and κL show an approximate parabolic trend, which results in extraordinarily high S and excellent thermoelectric properties, and zT even exceeds 1.4(1.09) in IrSb3(CoSb3) at 54(58) GPa. This anomalous behavior arises from the electron distribution and intrinsic scattering processes. Further analyses indicate that (i) nonbonding electron pairs of Sb atoms are gradually transferred to the region between Co(Ir) and Sb atoms as the pressure increases, which leads to the formation of a partial metallic bond and thus the band gap first expands and then shrinks; (ii) the change of the strength of the anharmonic phonon scattering process results in the variation of κL. As a result, these behaviors cause excellent thermoelectric properties. Our results provide insight into the thermal transport properties of skutterudites, meanwhile, forecast potential high pressure applications for thermoelectric materials.

Phonon thermal transport in a class of graphene allotropes from first principles.

Utilizing first principle calculations combined with the phonon Boltzman transport equation (PBTE), we systematically investigate the phonon thermal transport properties of α, ß and γ graphyne, a class of graphene allotropes. Strikingly, at room temperature, a low lattice thermal conductivity κL of 21.11, 22.3, and 106.24 W m-1 K-1 is obtained in α, ß and γ graphyne, respectively, which are much lower than that of graphene. We observe contributions from the phonon modes below the specified frequency and find that many optical phonon modes play critical roles in the phonon thermal transport. These optic modes participate in thermal transport, enhancing the phonon scattering process, thus leading to the low κL value. Our results provide insights into the thermal transport of graphyne, and forecast its potential applications for thermoelectric and thermal barrier coatings.

Influence of school-level and family-level variables on Chinese college students' aggression.

With the frequent occurrence of campus violence, scholars have devoted increasing attention to college students' aggression. This study aims to estimate the prevalence of aggression in Chinese university students and identify factors that could influence their aggression. We can thus find methods to reduce the incidence of college students' aggression in the future. A multi-stage stratified sampling procedure was used to select university students (N = 4565) aged 16-25 years in Harbin. The Aggression Questionnaire, the Adolescent Self-Rating Life Events Checklist and the Social Support Revalued Scale were used to collect data. Females reported lower levels of aggression than males (p < .001). A multiple linear regression analysis was conducted to determine the influence of factors of aggression, and the model was highly significant (R2 = .233, Ad R2 = .230, p < .01). The results show that the aggression is affected by gender, family-level and school-level variables. Aggression scores are significantly correlated with not only family-level or school-level variables independently, but their combination as well. We find that the risk factors for aggression include a dissatisfying profession, higher levels of study pressure, poor parental relationships, poor interpersonal relationships, the presence of siblings, punishment, health maladjustment, less subjective support, and lower levels of utilization of social support.

Prevalence and factors associated with occupational burnout among HIV/AIDS healthcare workers in China: a cross-sectional study.

BACKGROUND: Burnout is a psychosomatic syndrome characterized by three dimensions (emotional exhaustion [EE], feelings of depersonalization [DP], and reduced personal accomplishment [PA]). We determined the prevalence of burnout and mental health status between HIV/AIDS healthcare workers and other healthcare workers, and determined the factors associated with burnout of HIV/AIDS healthcare workers. METHODS: All participants were asked to complete a self-administered questionnaire. The participants were recruited from the departments of infectious diseases in four hospitals which treated HIV/AIDS. The questionnaire included demographics, the Maslach Burnout Inventory-General Survey (MBI-GS), the Symptom Checklist 90 (SCL-90), the Eysenck Personality Questionnaire (EPQ), and the Trait Coping Style Questionnaire (TCSQ). RESULTS: A total of 512 questionnaires were distributed; 501 questionnaires were completed and collected (the response rate was 97.9 %). After eliminating nine invalid questionnaires (1.80 %), 264 physicians and nurses caring for HIV/AIDS and 228 physicians and nurses caring for other infectious diseases provided valid responses (98.2 %). The HIV/AIDS healthcare workers' scores on the emotional exhaustion (F = 6.350, p = 0.012) and depersonalization dimensions (F = 8.533, p = 0.004) were significantly higher than other healthcare workers. The HIV/AIDS healthcare workers had higher total scores and positive items on the Symptom Checklist 90 (SCL-90) compared with other healthcare workers. Low job satisfaction, serious somatization, interpersonal sensitivity, poor quality of sleep, high psychoticism scores, and use of negative coping styles were frequently associated with burnout. CONCLUSIONS: Burnout was shown to be highly prevalent in HIV/AIDS healthcare workers, 76.9 % of whom met the accepted criteria for burnout. In addition, compared with other healthcare workers, HIV/AIDS healthcare workers experienced lower levels of psychological health. Interventions should be targeted at reducing the occurrence of burnout and alleviating psychological pressure amongst HIV/AIDS healthcare workers.

Using event-related potential P300 as an electrophysiological marker for differential diagnosis and to predict the progression of mild cognitive impairment: a meta-analysis.

P300 event-related potential component may sensitively predict mild cognitive impairment (MCI) progression. Here, pooled effect size estimates of P300 amplitude and latency were computed at midline electrodes among controls, MCI patients, and Alzheimer's disease (AD) patients. Baseline data were compared to one-year follow-up data. MCI patients showed decreased P300 amplitude and prolonged latency compared to controls. Pooled standardized mean differences (SMDs) were -0.67 (95 % CI -1.12 to -0.23, P = 0.003) and 0.90 (95 % CI 0.66-1.14, P < 0.00001), respectively. P300 latency decreased in MCI compared to AD patients where the pooled SMD was -0.52 (95 % CI -0.85 to -0.18, P = 0.003). Amplitude and latency differed between MCI baseline and follow-up. Pooled SMDs were 0.47 (95 % CI 0.29 to -0.65, P < 0.00001) and -0.52 (95 % CI -0.71 to -0.34, P < 0.00001), respectively. Group differences in MCI P300 latency existed compared to control and AD patients. P300 latency may therefore be a sensitive indicator for early cognitive decline or disease progression in MCI patients and identifying elderly patient progression to MCI and/or AD.

Colossal anomalous Hall effect in the layered antiferromagnetic EuAl2Si2 compound.

The anomalous Hall effect (AHE), significantly enhanced by the extrinsic mechanism, has attracted attention for its almost unlimited Hall response, which exceeds the upper limit of the Berry curvature mechanism. However, due to the high conductivity in the clean regime and weak skew scattering, it is a great challenge to obtain large anomalous Hall conductivities and large anomalous Hall angles at the same time. Here, we unveil a new magnetic metal system, EuAl2Si2, which hosts both colossal anomalous Hall conductivity (σAxy ≥ 104 Ω-1 cm-1) and large anomalous Hall angle (AHA >10%). The scaling relation suggests that the skew scattering mechanism is dominant in the colossal anomalous Hall response and gives rise to a large skew scattering constant. The large effective SOC and large magnetic moment may account for this anomaly. Our results indicate that EuAl2Si2 is a good platform to study the extrinsic AHE mechanism.

Identification of candidate genes associated with skin yellowness in yellow chickens.

The yellow color of the skin is an important economic trait for yellow chickens. Low and non-uniform skin yellowness would reduce economic efficiency. However, the regulatory mechanism of chicken skin yellowness has not been fully elucidated. In this study, we evaluated the skin yellowness of 819 chickens by colorimeter and digital camera, which are from the same batch and the same age of 2 pure lines with significant differences in skin yellowness. A total of 982 candidate differential expressed genes (DEGs) were detected in duodenal tissue by RNA-seq analysis for high and low yellowness chickens. Among the DEGs, we chose fatty acid translocase (CD36) gene and identified a single nucleotide polymorphism (SNP) upstream of the CD36 gene that was significantly associated with skin yellowness at multiple parts of the chicken, and its different genotypes had significant effects on the promoter activity of the CD36 gene. These findings will help to further elucidate the molecular mechanism of chicken skin yellowness and is helpful for improving chicken skin yellowness.

Trajectories and influencing factors in adolescent procrastination behavior throughout the COVID-19 pandemic: a four-wave prospective longitudinal study.

Background: Despite the growing attention given to adolescent behavior problems, little is known about the trajectories and factors that have influenced adolescent procrastination during the COVID-19 pandemic. This study monitors changes in procrastination behavior among Chinese adolescents during the pandemic and identifies vulnerable groups. Methods: A four-wave study using a representative sample of 11-to 18-year-olds in China was conducted, with baseline data collected in June 2020 (n = 4,156; 49% girls) and follow-ups in December 2020 (n = 3,392; 50% girls), August 2021 (n = 2,380; 48% girls), and October 2021 (n = 1,485; 49% girls). Procrastination behavior was assessed using the General Procrastination Scale. Latent growth curve models, latent growth mixture modes, and multivariate logistic regression models were used to describe the trajectory of procrastination and identify predictors of deterioration. Results: The proportion and overall trends of adolescent procrastination increased with the pandemic. Higher parental over-protection was a contributing factor to the higher baseline levels leading to the faster growth of adolescent procrastination. The model identified three distinct trajectories of low-increasing [including 2,057 participants (49.5%)], moderate-stable [including 1,879 participants (45.2%)], and high-decreasing procrastination [including 220 participants (5.3%)]. More daily leisure screen-time, lower frequency of exercise weekly, and dissatisfaction with distance learning were the top three risk factors for moderate-stable and high-decreasing procrastination compared to low-increasing procrastination. Adolescents with mothers with a higher level of education were more liable to be high-decreasing procrastination than moderate-stable procrastination. Conclusion: The proportion and overall trends of adolescent procrastination increased with the pandemic. The categories of procrastination among adolescents during that time period were probed. Also, the study further clarified the risk factors for severe and moderate procrastination relative to no procrastination. Thus, effective procrastination prevention and intervention strategies need to be implemented to support adolescents, particularly those at risk.

QPCTL Affects the Daily Weight Gain of the F2 Population and Regulates Myogenic Cell Proliferation and Differentiation in Chickens.

Molecular breeding can accelerate the process of animal breeding and improve the breeding efficiency. To date, many Indel molecular markers have been identified in livestock and poultry, but how Indels affect economic traits is not well understood. For molecular breeding, it is crucial to reveal the mechanism of action of Indels and to provide more accurate information. The purpose of this study was to investigate how the 52/224-bp multiallelic Indels of the chicken QPCTL promoter area affect the daily weight gain of chickens and the potential regulatory mechanism of the QPCTL gene. The analysis was conducted by association analysis, qPCR, dual-fluorescence assay and Western blotting. The results showed that Indels in the QPCTL promoter region were significantly associated with the daily weight gain in chickens and that QPCTL expression showed a decreasing trend in embryonic breast muscle tissues. Furthermore, QPCTL expression was significantly higher in breast muscle tissues of the AC genotype than in those of the AB and BB genotypes. Based on the transcriptional activity results, the pGL3-C vector produced more luciferase activity than pGL3-A and pGL3-B. In addition, overexpression of QPCTL promoted chicken primary myoblast (CPM) proliferation and inhibited differentiation. The results of this study suggest that Indels in the promoter region of the QPCTL gene may regulate the proliferation and differentiation of CPMs by affecting the expression of QPCTL, which ultimately affects the growth rate of chickens. These Indels have important value for the molecular breeding of chickens, and QPCTL can be used as a candidate gene to regulate and improve chicken growth and development.

Integrative Analysis of Metabolomic and Transcriptomic Data Reveals the Antioxidant Potential of Dietary Lutein in Chickens.

Lutein can increase the body's skin color and has antioxidant potential. However, how it affects lipid metabolism and oxidative stress in chickens remains unknown. In this study, 74-day-old male chickens raised on feed supplemented with lutein had higher hip, back, breast, leg, shin and abdominal fat yellowness than the control group, and the livers of chickens in the lutein group had higher superoxide dismutase and glutathione peroxidase and lower malondialdehyde activities. To clarify the potential regulatory network regulated by lutein, we used RNA-seq and nontargeted metabolomics to detect changes in the male chicken liver and plasma, respectively. A total of 243 differentially expressed genes were significantly enriched in cytokine-cytokine receptor interaction signaling pathways, among others. A total of 237 significantly different metabolites were enriched in lysine biosynthesis and degradation and glycerophospholipid metabolism signaling pathways, among others. Finally, we comprehensively analyzed metabolome and transcriptome data and found that many differentially expressed genes and significantly different metabolites play crucial roles in lipid metabolism and oxidative stress. In summary, dietary lutein can improve male chicken skin yellowness and antioxidant indices and affect liver gene expression and plasma metabolites and may help improve the health of chickens.

Factors Influencing Post-traumatic Stress Symptoms in Chinese Adolescents During the COVID-19 Pandemic.

To investigate the prevalence of post-traumatic stress symptoms (PTSSs) and analyze the influencing factors of PTSS among adolescents in a large sample study during the COVID-19 pandemic, we did a cross-sectional study by collecting demographic data and mental health measurements from a large group of 175,318 adolescents in 32 Chinese provinces and autonomous regions, using the Impact of Event Scale-Revised (IES-R) that was used to measure the PTSS of the participants. The results showed that the prevalence of PTSS was 35.7% in Chinese adolescents during the COVID-19 pandemic. Binary logistic regression analysis showed that, for the personal risk factors, the older age, female gender, the personality domains of extroversion, the irregular sleep schedule, the lack of aerobic exercise, and the lack of peer support were associated with the higher levels of PTSS. The family subjective and objective factors were associated with higher levels of PTSS. Our findings suggested that family factors are the most important factors that affect Chinese adolescents' PTSS due to the longtime home quarantine.

Association of the Combined Effects between Insulin-Like Growth Factor-1 Gene Polymorphisms and Negative Life Events with Major Depressive Disorder among Chinese population in the Context of Oxidative Stress.

Background: Oxidative stress may be increased in a number of psychiatric disorders, including major depressive disorder (MDD). MDD has been shown to be related to insulin-like growth factor-1 (IGF-1) as well as to negative life events; exploring the interaction of IGF-1 polymorphisms and negative life events on the risk of MDD is needed. The aim of this study was to analyze the single and combined effects of IGF-1 polymorphisms (rs972936 and rs978458) and negative life events with MDD among Chinese population. Methods: 420 MDD patients (according to DSM-V) and 420 age- and gender-matched control subjects were recruited in a case-control study. Negative life events were assessed using standard rating scales. IGF-1 rs972936 and rs978458 were identified by sequencing. The chi-square (χ 2) tests were performed to explore the association of negative life events and IGF-1 polymorphisms with MDD. Results: Our results found that the negative life events were associated with the risk of MDD (P < 0.001; OR = 3.28, 95% CI: 2.19-4.85). The genotypes of IGF-1 were associated with the risk of MDD (P < 0.001); carrying the IGF-1 rs972936 C allele (OR = 1.53, 95% CI: 1.26-1.85) and rs978458 T allele (OR = 1.92, 95% CI: 1.58-2.34) had a higher risk of MDD. The combined effects between IGF-1 rs978458 and negative life events were associated with the risk of MDD (P < 0.05; OR = 2.94, 95% CI: 1.23-7.03), but IGF-1 rs972936 was not associated (P > 0.05). Conclusions: Based on the oxidative stress hypothesis, we confirm that carrying IGF-1 rs972936 C allele and rs978458 T allele have a higher risk of MDD and the combined effects between IGF-1 rs978458 and negative life events were associated with the risk of MDD among Chinese population.

The Gender-Specific Interaction of DVL3 and GSK3ß Polymorphisms on Major Depressive Disorder Susceptibility in a Chinese Han Population: A Case-Control Study.

Based on the "oxidative stress hypothesis" of major depressive disorder (MDD), cells regulate their structure through the Wnt pathway. Little is known regarding the interactions of dishevelled 3 (DVL3) and glycogen synthase kinase 3 beta (GSK3ß) polymorphisms with MDD. The aim of the current study was to verify the relationship between DVL3 and GSK3ß genetic variants in a Chinese Han population and further to evaluate whether these interactions exhibit gender-specificity. A total of 1136 participants, consisting of 541 MDD patients and 595 healthy subjects, were recruited. Five single-nucleotide polymorphisms (SNPs) of DVL3/GSK3ß were selected to assess their interaction by use of a generalized multifactor dimensionality reduction method. The genotype and haplotype frequencies of DVL3/GSK3ß polymorphisms were significantly different between patients and controls for DVL3 rs1709642 (P < 0.01) and GSK3ß rs334558, rs6438552, and rs2199503 (P < 0.01). In addition, our results also showed that there were significant interaction effects between DVL3 and GSK3ß polymorphisms and the risk of developing MDD, particularly in women. The interaction between DVL3 (rs1709642) and GSK3ß (rs334558, rs6438552) showed a cross-validation (CV) consistency of 10/10, a P value of 0.001, and a testing accuracy of 59.22%, which was considered as the best generalized multifactor dimensionality reduction (GMDR) model. This study reveals the interaction between DVL3 and GSK3ß polymorphisms on MDD susceptibility in a female Chinese Han population. The effect of gender should be taken into account in future studies that seek to explore the genetic predisposition to MDD relative to the DVL3 and GSK3ß genes.

Relationship between psychological capital and depression in Chinese physicians: The mediating role of organizational commitment and coping style.

Background: It is well known that the medical profession is a high-risk practice, with intense work and complex situations. The physicians are prone to suffer from depression due to occupational stress under high workloads for long periods of time. Depression not only impairs physicians' mental health, but also affects the quality of health services, so it is important to explore the factors and mechanisms affecting depression among physicians. Methods: In this cross-sectional study, 1,139 physicians from Heilongjiang Province were surveyed by cluster sampling procedures. The questionnaires included Psychological Capital Questionnaire, Chinese Employee Organizational Commitment Questionnaire, Trait Coping Style Questionnaire and Self-rating Depression Scale. Pearson correlation analysis and Bootstrap were used for statistical analysis. Results: This study found that 41.6% of physicians suffering from depression. Among them, 17.0% of physicians showed moderate depression, and 2.6% of physicians exhibited severe depression. The serial-multiple mediation of organizational commitment and positive coping styles in the relationship between psychological capital and depression was significant. Conclusion: The results showed that the psychological capital was sequentially associated with increased organizational commitment, and then increased positive coping styles, which resulted in reduced depression among physicians.

Sleep quality and creativity in Chinese college student during the COVID-19 pandemic: The mediating role of executive function.

Background: COVID-19 has impacted adolescents' interpersonal relationships, life attitudes, and mental health during the past 3 years. However, previous studies predominantly focused on negative problems, while few studies assessed the situation of teenagers from the perspective of positive psychology. Therefore, this study explores the creativity level of Chinese college students during the COVID-19 pandemic, the relationship between sleep quality and creativity, and the mediating role of executive function. Method: A cross-sectional study was conducted across six colleges in Heilongjiang in China, with a sample of 4,258 college students recruited via stratified cluster sampling. Data were collected through an online survey. A mediation model was constructed, and SPSS PROCESS macro was used to analyze the data. Results: The creativity score of Chinese college students during the COVID-19 pandemic was 106.48 ± 13.61. Correlation analysis demonstrated that sleep quality correlated negatively with creativity (r = -0.08, P < 0.01) but positively with executive function (r=0.45, P < 0.01), whilst executive function correlated negatively with creativity (r = -0.10, P < 0.01). Moreover, the mediation model revealed that executive function partially mediated the relationship between sleep quality and creativity in college students (indirect effect = -0.017, SE = 0.004, 95% CI = [-0.025, -0.008]). Executive function accounted for 48.6% of the variance in college students' creativity. Conclusion: School administrators should implement measures such as sleep education to enhance students' sleep quality. Concurrently, curriculum and assessment implementation should enhance executive function. Such measures can contribute to improved student creativity, thus helping students overcome the negative emotional impact of the COVID-19 pandemic.

The Impact of Transformational Leadership on Physicians' Performance in China: A Cross-Level Mediation Model.

Transformational leadership has been becoming increasingly vital to the provision of high-quality health care, particularly during major public health emergencies. The present study aims to investigate the impact of transformational leadership on physicians' performance and explore the cross-level underlying mechanisms with achievement motivations and coping styles among Chinese physicians. During 2017-2019, 1,527 physicians of 101 departments were recruited from six hospitals in China with a cluster random sampling method. Participants completed several questionnaires regarding their job performance, achievement motivations, coping styles, and transformational leadership. Multilevel mediation effects were tested using cross-level path analysis. The result of this study indicated that transformational leadership was applied well in Chinese medical settings with a score of 101.56 ± 6.42. The hierarchical linear model showed that transformational leadership had a cross-level direct positive effect on physicians' performance (ß = 1.524, p < 0.05). Furthermore, results of cross-level path analyses revealed that transformational leadership contributed to physicians' performance by sequentially influencing achievement motivations first and then coping styles. In addition, the path "transformational leadership → positive coping (PC) style → physicians' performance" showed the strongest cross-level indirect effect. In summary, public health leaders should enhance physicians' performance by promoting individual development, especially achievement motivation and PC style.

Perceived Stress and Smartphone Addiction in Medical College Students: The Mediating Role of Negative Emotions and the Moderating Role of Psychological Capital.

Background: Many studies have confirmed the existence of an extremely close relationship between smartphone addiction and perceived stress. However, the mediating and moderating mechanisms underlying the association between perceived stress and smartphone addiction in medical college students remain largely unexplored. Methods: A questionnaire was distributed among a total of 769 medical college students in Heilongjiang Province, China. Participants completed measures of perceived stress, smartphone addiction, negative emotions, and psychological capital. Pearson's correlation analysis was used to test the correlations between variables. The analysis of a moderated mediation model was performed using Hayes's PROCESS macro. Results: Pearson's correlation analysis indicated that perceived stress (r = 0.18, p < 0.01) and negative emotions (r = 0.31, p < 0.01) were positively correlated with smartphone addiction, and psychological capital was negatively correlated with smartphone addiction (r = -0.29, p < 0.01). The moderated mediation analysis indicated that negative emotions partially mediated the association between perceived stress and smartphone addiction [mediation effect accounted for 33.3%, SE = 0.10, 95% CI = (0.10, 0.24)], and the first stage of the mediation process was significantly moderated by psychological capital [moderated mediation = -0.01, SE = 0.01, 95% CI = (-0.01, -0.00)]. Conclusion: Negative emotions play a mediating role between perceived stress and smartphone addiction, and psychological capital plays an important moderating role in the first stage of the mediation process.