Objectives:In recent years,mental health has emerged as a pressing public health concern in China,driven by mounting societal pressures and fast-paced urban lifestyles.Physical activity,a well-established means of enh...Objectives:In recent years,mental health has emerged as a pressing public health concern in China,driven by mounting societal pressures and fast-paced urban lifestyles.Physical activity,a well-established means of enhancing psychological well-being,has received growing scholarly and policy attention.This study uses panel data from the 2020 and 2022 waves of the China Family Panel Studies(CFPS)to examine the impact of exercise frequency on mental health(with indicators such as CESD-8 depression scores)among college students and young employees,thereby providing empirical support for targeted mental health interventions.Methods:This study examines the relationship between individual exercise frequency and mental health among college students and young employees,using panel data from the 2020 and 2022 waves of the China Family Panel Studies(CFPS),with the Chinese version of the 8-item Center for Epidemiologic Studies Depression Scale(CESD-8)depression scores,self-rated health,and life satisfaction as outcome variables.Specifically,this study tests three hypotheses:(H1)increased exercise frequency significantly reduces depression symptoms and enhances well-being;(H2)the effects of exercise vary by social roles,with stronger mental health benefits among employed individuals and those with lower education;and(H3)lifestyle factors such as smoking amount,sleep duration,and Body Mass Index(BMI)partially mediate the relationship between exercise and mental health.Employing a two-way fixed effects model,baseline results indicate that a one-unit increase in exercise frequency significantly reduces the CESD-8 score by 0.183 points.To address potential endogeneity and spurious regression concerns,an instrumental variable(IV)approach is further applied.The heterogeneity analysis differentiates between students and employed individuals.Results:Among students,the effects of exercise on mental health are not statistically significant,regardless of education level.In contrast,for the employed,exercise demonstrates a significant positive impact on mental health,with particularly pronounced effects among those with lower educational attainment.These findings underscore the importance of promoting exercise as part of comprehensive mental health strategies.Mediation analysis indicates that the beneficial effect of exercise on mental health is partially transmitted through reductions in adverse health behaviors,especially smoking.Conclusions:Policymakers should integrate physical activity promotion into health interventions,prioritizing vulnerable groups to enhance psychological resilience and foster inclusive,health-oriented development.展开更多
In recent years,there has been a growing global demand for carbon neutrality and energy efficiency,which are expected to become long-term trends.In the field of architecture,an effective approach to achieve this is to...In recent years,there has been a growing global demand for carbon neutrality and energy efficiency,which are expected to become long-term trends.In the field of architecture,an effective approach to achieve this is to reduce heat loss in buildings.Vacuum insulation panels(VIPs),a type of high-performance insulation material,have been increasingly utilised in the construction industry and have played an increa-singly important role as their performance and manufacturing processes continue to improve.This paper provides a review of the factors affecting the thermal conductivity of VIPs and presents a detailed overview of the research progress on core materials,barrier films,and getters.The current research status of VIPs is summarised,including their thermal conductivity,service life,and thermal bridging effects,as well as their applications in the field of architecture.This review aims to provide a comprehensive understanding for relevant practitioners on the factors influencing the thermal conductivity of VIPs,and based on which,measures can be taken to produce VIPs with lower thermal conductivity and longer service life.展开更多
The concept of non-Hermitian mechanics introduces new dimensions to metamaterial research,yet current studies have primarily focused on wave manipulation,neglecting the vibration transmittance characteristics of finit...The concept of non-Hermitian mechanics introduces new dimensions to metamaterial research,yet current studies have primarily focused on wave manipulation,neglecting the vibration transmittance characteristics of finite-size metamaterials with boundary reflections.This paper explores the asymmetric vibration transmittance characteristics of a simply supported NonHermitian Metamaterial Panel(NHMP)with two lossy resonators,under the impact of supersonic aerodynamic forces.By examining the non-Hermiticity of a non-aerodynamically loaded NHMP and a host panel aeroelastic system separately,we demonstrate that the NHMP subjected to supersonic aerodynamic force is a complex non-Hermitian system,exhibiting asymmetric vibration transmittance driven by both the fluid-structure interaction effect and lossy resonators.We theoretically and numerically clarify that an ideal aeroelastic system,such as a host panel aeroelastic system,functions as a non-Hermitian mechanical system due to the fluid-structure interaction effect,with the critical flutter point aligning with the Exceptional Point(EP).The results of this study indicate that at low dynamic pressures,the lossy resonators primarily govern asymmetric vibration transmittance,whereas at high dynamic pressures,the fluid-structure interaction effect becomes the dominant factor.Notably,at the EP,asymmetric vibration transmittance is unaffected by the mass ratio of lossy resonators,which is attributed to the invariance of the operational deflection shapes of the NHMP at the EP.This study offers a novel perspective on panel aeroelastic systems and nonHermitian metamaterials,advancing the field through its comprehensive analyses.展开更多
Objective To study the causal relationship between R&D investment and enterprise performance of domestic pharmaceutical enterprises.Methods Panel data model was adopted for empirical analysis.Results and Conclusio...Objective To study the causal relationship between R&D investment and enterprise performance of domestic pharmaceutical enterprises.Methods Panel data model was adopted for empirical analysis.Results and Conclusion Increasing the R&D investment intensity of pharmaceutical enterprises in the Yangtze River Delta and Zhejiang by 1%will increase their profit margins by 0.79%and 0.46%.On the contrary,if the profit margin increases by 1%,the R&D investment intensity will increase by 0.25%and 0.19%.If the profit margin of pharmaceutical enterprises in Beijing,Tianjin,Hebei,Chengdu,Chongqing and other regions increases by 1%,the R&D investment intensity will increase by 0.14%,0.07%and 0.1%,respectively,which are lower than those in the Yangtze River Delta and Zhejiang.The relationship between R&D investment and enterprise performance of pharmaceutical enterprises in the Yangtze River Delta and Zhejiang Province is Granger causality,showing a two-way positive effect.Profits and R&D investment of pharmaceutical enterprises in Beijing,Tianjin,Hebei,Chengdu,Chongqing and other regions are also Granger causality.But in the Pearl River Delta,profits and R&D investment have not passed the stability test,it is impossible to determine the causality between them.展开更多
文摘Objectives:In recent years,mental health has emerged as a pressing public health concern in China,driven by mounting societal pressures and fast-paced urban lifestyles.Physical activity,a well-established means of enhancing psychological well-being,has received growing scholarly and policy attention.This study uses panel data from the 2020 and 2022 waves of the China Family Panel Studies(CFPS)to examine the impact of exercise frequency on mental health(with indicators such as CESD-8 depression scores)among college students and young employees,thereby providing empirical support for targeted mental health interventions.Methods:This study examines the relationship between individual exercise frequency and mental health among college students and young employees,using panel data from the 2020 and 2022 waves of the China Family Panel Studies(CFPS),with the Chinese version of the 8-item Center for Epidemiologic Studies Depression Scale(CESD-8)depression scores,self-rated health,and life satisfaction as outcome variables.Specifically,this study tests three hypotheses:(H1)increased exercise frequency significantly reduces depression symptoms and enhances well-being;(H2)the effects of exercise vary by social roles,with stronger mental health benefits among employed individuals and those with lower education;and(H3)lifestyle factors such as smoking amount,sleep duration,and Body Mass Index(BMI)partially mediate the relationship between exercise and mental health.Employing a two-way fixed effects model,baseline results indicate that a one-unit increase in exercise frequency significantly reduces the CESD-8 score by 0.183 points.To address potential endogeneity and spurious regression concerns,an instrumental variable(IV)approach is further applied.The heterogeneity analysis differentiates between students and employed individuals.Results:Among students,the effects of exercise on mental health are not statistically significant,regardless of education level.In contrast,for the employed,exercise demonstrates a significant positive impact on mental health,with particularly pronounced effects among those with lower educational attainment.These findings underscore the importance of promoting exercise as part of comprehensive mental health strategies.Mediation analysis indicates that the beneficial effect of exercise on mental health is partially transmitted through reductions in adverse health behaviors,especially smoking.Conclusions:Policymakers should integrate physical activity promotion into health interventions,prioritizing vulnerable groups to enhance psychological resilience and foster inclusive,health-oriented development.
文摘In recent years,there has been a growing global demand for carbon neutrality and energy efficiency,which are expected to become long-term trends.In the field of architecture,an effective approach to achieve this is to reduce heat loss in buildings.Vacuum insulation panels(VIPs),a type of high-performance insulation material,have been increasingly utilised in the construction industry and have played an increa-singly important role as their performance and manufacturing processes continue to improve.This paper provides a review of the factors affecting the thermal conductivity of VIPs and presents a detailed overview of the research progress on core materials,barrier films,and getters.The current research status of VIPs is summarised,including their thermal conductivity,service life,and thermal bridging effects,as well as their applications in the field of architecture.This review aims to provide a comprehensive understanding for relevant practitioners on the factors influencing the thermal conductivity of VIPs,and based on which,measures can be taken to produce VIPs with lower thermal conductivity and longer service life.
基金co-supported by the National Natural Science Foundation of China(Nos.12372170,12402104 and 12072276)the National Science Basic Research Program of Shaanxi Province,China(No.2022JM-047)the 111 Project of China(No.BP0719007)。
文摘The concept of non-Hermitian mechanics introduces new dimensions to metamaterial research,yet current studies have primarily focused on wave manipulation,neglecting the vibration transmittance characteristics of finite-size metamaterials with boundary reflections.This paper explores the asymmetric vibration transmittance characteristics of a simply supported NonHermitian Metamaterial Panel(NHMP)with two lossy resonators,under the impact of supersonic aerodynamic forces.By examining the non-Hermiticity of a non-aerodynamically loaded NHMP and a host panel aeroelastic system separately,we demonstrate that the NHMP subjected to supersonic aerodynamic force is a complex non-Hermitian system,exhibiting asymmetric vibration transmittance driven by both the fluid-structure interaction effect and lossy resonators.We theoretically and numerically clarify that an ideal aeroelastic system,such as a host panel aeroelastic system,functions as a non-Hermitian mechanical system due to the fluid-structure interaction effect,with the critical flutter point aligning with the Exceptional Point(EP).The results of this study indicate that at low dynamic pressures,the lossy resonators primarily govern asymmetric vibration transmittance,whereas at high dynamic pressures,the fluid-structure interaction effect becomes the dominant factor.Notably,at the EP,asymmetric vibration transmittance is unaffected by the mass ratio of lossy resonators,which is attributed to the invariance of the operational deflection shapes of the NHMP at the EP.This study offers a novel perspective on panel aeroelastic systems and nonHermitian metamaterials,advancing the field through its comprehensive analyses.
基金Shenyang Pharmaceutical University Young and Middle aged Teacher Career Development Support PlanPublic Welfare Research Fund for Scientific Undertakings of Liaoning Province in 2022(Soft Science Research Plan)(No.2022JH4/10100040).
文摘Objective To study the causal relationship between R&D investment and enterprise performance of domestic pharmaceutical enterprises.Methods Panel data model was adopted for empirical analysis.Results and Conclusion Increasing the R&D investment intensity of pharmaceutical enterprises in the Yangtze River Delta and Zhejiang by 1%will increase their profit margins by 0.79%and 0.46%.On the contrary,if the profit margin increases by 1%,the R&D investment intensity will increase by 0.25%and 0.19%.If the profit margin of pharmaceutical enterprises in Beijing,Tianjin,Hebei,Chengdu,Chongqing and other regions increases by 1%,the R&D investment intensity will increase by 0.14%,0.07%and 0.1%,respectively,which are lower than those in the Yangtze River Delta and Zhejiang.The relationship between R&D investment and enterprise performance of pharmaceutical enterprises in the Yangtze River Delta and Zhejiang Province is Granger causality,showing a two-way positive effect.Profits and R&D investment of pharmaceutical enterprises in Beijing,Tianjin,Hebei,Chengdu,Chongqing and other regions are also Granger causality.But in the Pearl River Delta,profits and R&D investment have not passed the stability test,it is impossible to determine the causality between them.
