Introduction:Nutrition knowledge(NK)is a key modifiable factor influencing the dietary behavior and nutritional status of children.Currently,nationally representative data assessing NK among Chinese junior high school...Introduction:Nutrition knowledge(NK)is a key modifiable factor influencing the dietary behavior and nutritional status of children.Currently,nationally representative data assessing NK among Chinese junior high school students are unavailable.This study aimed to assess NK levels using recent,nationally representative data from China.Methods:A multistage stratified random cluster sampling method was used to select 28,629 junior high school students from 195 survey sites across 31 provincial-level administrative divisions in China.Data were collected using a standardized questionnaire developed using rigorous scientific procedures.NK awareness rates were described as weighted prevalence rates with 95%confidence intervals(CIs).Subgroup comparisons were performed using the Rao–Scott chisquare test.Results:The overall NK awareness rate among Chinese junior high school students was 40.0%(95%CI:36.5%–43.5%).The rates for the five dimensions,dietary recommendations,nutrient content of foods,food and health,food choices,and food safety,were 20.1%,46.2%,65.3%,65.2%,and 65.2%,respectively.The analysis revealed significant variations in overall and dimension-specific awareness rates across groups.Boys,students from rural and western regions,and students from families with lower socioeconomic status had poorer NK levels than their counterparts.Among the 10 knowledge points with the lowest correct rates,seven belonged to dietary recommendations,two to food safety,and one to food and health.Conclusion:NK awareness rates among junior high school students require improvement,especially regarding dietary recommendations,which remain a key component of students’nutrition education.Boys,students from rural and western regions,and students from families with lower socioeconomic status should be the key populations for NK dissemination in the future.展开更多
This paper continues to study the explicit two-stage fourth-order accurate time discretizations[5-7].By introducing variable weights,we propose a class of more general explicit one-step two-stage time discretizations,...This paper continues to study the explicit two-stage fourth-order accurate time discretizations[5-7].By introducing variable weights,we propose a class of more general explicit one-step two-stage time discretizations,which are different from the existing methods,e.g.the Euler methods,Runge-Kutta methods,and multistage multiderivative methods etc.We study the absolute stability,the stability interval,and the intersection between the imaginary axis and the absolute stability region.Our results show that our two-stage time discretizations can be fourth-order accurate conditionally,the absolute stability region of the proposed methods with some special choices of the variable weights can be larger than that of the classical explicit fourth-or fifth-order Runge-Kutta method,and the interval of absolute stability can be almost twice as much as the latter.Several numerical experiments are carried out to demonstrate the performance and accuracy as well as the stability of our proposed methods.展开更多
Background To investigate the relationship of age at first separation from parents(AFSP)with suicidal ideation(SI),suicide planning(SP)and suicide attempts(SA)among left-behind children(LBC)in China and the mediating ...Background To investigate the relationship of age at first separation from parents(AFSP)with suicidal ideation(SI),suicide planning(SP)and suicide attempts(SA)among left-behind children(LBC)in China and the mediating effect of traumatic events(TEs).Methods This cross-sectional study employed a multistage sampling method to conduct questionnaire surveys in six high-concentrated LBC provinces.Logistic regression and restricted cubic splines were performed to investigate the association of AFSP with SI,SP and SA,and meta-analysis(I2)was used to assess the heterogeneity.Causal mediation analysis(structural equation modelling)was used to evaluate the mediating effect of TEs,and bootstrap resampling was employed to assess the robustness of the causal mediation analysis.Results A total of 12162(6269 LBC)participants were included in this study;the prevalence rates of SI,SP and SA among LBC were 30.7%,18.6%and 11.9%;and LBC had a higher risk of SI(OR:1.32),SP(OR:1.40)and SA(OR:1.25)than non-LBC,all p<0.001.AFSP was negatively associated with SI,SP and SA,particularly peaking before 2 years old.LBC with AFSP<2 years old had a higher risk of SI(OR 2.65;95%CI 2.17 to 3.24;p<0.001),SP(OR 2.63;95%CI 3.36 to 4.29;p<0.001)and SA(OR 2.04;95%CI 2.73 to 3.63;p<0.001).TEs mediated the increased risk of SI(average causal mediation effect(ACME)0.03–0.07;proportion(Prop)40–54%;all p<0.001),SP(ACME 0.03–0.06;Prop 39–61%;all p<0.001)and SA(ACME 0.02–0.04;Prop 53–80%;all p<0.01).Conclusions We found that AFSP was associated with SI,SP and SA,mediated by TEs.Our findings supported the necessity of reducing SI,SP and SA risks among LBC and highlighted the need to consider AFSPs and TEs in intervention strategies.展开更多
基金Approved by the Medical Ethical Review Committee of the National Institute for Nutrition and Health,Chinese Center for Disease Control and Prevention(No.2022-037).
文摘Introduction:Nutrition knowledge(NK)is a key modifiable factor influencing the dietary behavior and nutritional status of children.Currently,nationally representative data assessing NK among Chinese junior high school students are unavailable.This study aimed to assess NK levels using recent,nationally representative data from China.Methods:A multistage stratified random cluster sampling method was used to select 28,629 junior high school students from 195 survey sites across 31 provincial-level administrative divisions in China.Data were collected using a standardized questionnaire developed using rigorous scientific procedures.NK awareness rates were described as weighted prevalence rates with 95%confidence intervals(CIs).Subgroup comparisons were performed using the Rao–Scott chisquare test.Results:The overall NK awareness rate among Chinese junior high school students was 40.0%(95%CI:36.5%–43.5%).The rates for the five dimensions,dietary recommendations,nutrient content of foods,food and health,food choices,and food safety,were 20.1%,46.2%,65.3%,65.2%,and 65.2%,respectively.The analysis revealed significant variations in overall and dimension-specific awareness rates across groups.Boys,students from rural and western regions,and students from families with lower socioeconomic status had poorer NK levels than their counterparts.Among the 10 knowledge points with the lowest correct rates,seven belonged to dietary recommendations,two to food safety,and one to food and health.Conclusion:NK awareness rates among junior high school students require improvement,especially regarding dietary recommendations,which remain a key component of students’nutrition education.Boys,students from rural and western regions,and students from families with lower socioeconomic status should be the key populations for NK dissemination in the future.
基金partially supported by the Special Project on Highperformance Computing under the National Key R&D Program(No.2020YFA0712002)the National Natural Science Foundation of China(No.12126302,12171227).
文摘This paper continues to study the explicit two-stage fourth-order accurate time discretizations[5-7].By introducing variable weights,we propose a class of more general explicit one-step two-stage time discretizations,which are different from the existing methods,e.g.the Euler methods,Runge-Kutta methods,and multistage multiderivative methods etc.We study the absolute stability,the stability interval,and the intersection between the imaginary axis and the absolute stability region.Our results show that our two-stage time discretizations can be fourth-order accurate conditionally,the absolute stability region of the proposed methods with some special choices of the variable weights can be larger than that of the classical explicit fourth-or fifth-order Runge-Kutta method,and the interval of absolute stability can be almost twice as much as the latter.Several numerical experiments are carried out to demonstrate the performance and accuracy as well as the stability of our proposed methods.
基金supported by the National Social Science Fund of China(NSSFC)(Grant No 20BSH066,JZ).
文摘Background To investigate the relationship of age at first separation from parents(AFSP)with suicidal ideation(SI),suicide planning(SP)and suicide attempts(SA)among left-behind children(LBC)in China and the mediating effect of traumatic events(TEs).Methods This cross-sectional study employed a multistage sampling method to conduct questionnaire surveys in six high-concentrated LBC provinces.Logistic regression and restricted cubic splines were performed to investigate the association of AFSP with SI,SP and SA,and meta-analysis(I2)was used to assess the heterogeneity.Causal mediation analysis(structural equation modelling)was used to evaluate the mediating effect of TEs,and bootstrap resampling was employed to assess the robustness of the causal mediation analysis.Results A total of 12162(6269 LBC)participants were included in this study;the prevalence rates of SI,SP and SA among LBC were 30.7%,18.6%and 11.9%;and LBC had a higher risk of SI(OR:1.32),SP(OR:1.40)and SA(OR:1.25)than non-LBC,all p<0.001.AFSP was negatively associated with SI,SP and SA,particularly peaking before 2 years old.LBC with AFSP<2 years old had a higher risk of SI(OR 2.65;95%CI 2.17 to 3.24;p<0.001),SP(OR 2.63;95%CI 3.36 to 4.29;p<0.001)and SA(OR 2.04;95%CI 2.73 to 3.63;p<0.001).TEs mediated the increased risk of SI(average causal mediation effect(ACME)0.03–0.07;proportion(Prop)40–54%;all p<0.001),SP(ACME 0.03–0.06;Prop 39–61%;all p<0.001)and SA(ACME 0.02–0.04;Prop 53–80%;all p<0.01).Conclusions We found that AFSP was associated with SI,SP and SA,mediated by TEs.Our findings supported the necessity of reducing SI,SP and SA risks among LBC and highlighted the need to consider AFSPs and TEs in intervention strategies.
