Purpose:To contribute to the study of networks and graphs.Design/methodology/approach:We apply standard mathematical thinking.Findings:We show that the distance distribution in an undirected network Lorenz majorizes t...Purpose:To contribute to the study of networks and graphs.Design/methodology/approach:We apply standard mathematical thinking.Findings:We show that the distance distribution in an undirected network Lorenz majorizes the one of a chain.As a consequence,the average and median distances in any such network are smaller than or equal to those of a chain.Research limitations:We restricted our investigations to undirected,unweighted networks.Practical implications:We are convinced that these results are useful in the study of small worlds and the so-called six degrees of separation property.Originality/value:To the best of our knowledge our research contains new network results,especially those related to frequencies of distances.展开更多
Static models of accessibility are usually based on the fixed distance or Average Travel Time(ATT)models.Because of ignoring the traffic as a dynamic process affecting the accessibility through the change of Travel Ti...Static models of accessibility are usually based on the fixed distance or Average Travel Time(ATT)models.Because of ignoring the traffic as a dynamic process affecting the accessibility through the change of Travel Time(TT),these models lead to unperceived temporal inequities.In contrast to the consideration of the temporal Variation of TT(VTT)in the previous studies,the variation of traffic-related TT and its relations with network distance has not been considered.In this study,relations between VTT and network distance to access urban parks in Tehran megacity has been modeled.Traffic maps at five times of day are used to produce TT maps of Traffic Analysis Zones(TAZs)to their 3-closest parks.Comparison of the Gini coefficients of accessibility show significant inequities of accessibility at different times of day.Relations between the distance,ATT,and TT_(max) are modeled by statistical analysis.Results show both TT and TTmax have significant positive relations with distance and traffic and reach their maximum at 6 p.m.Observation of significant relations between distance,ATT,TT_(max),and VTT provides interesting knowledge for the conversion of temporal measures of equity(TT)to a physical measure of equity(distance).A simple application of these findings for effective management of the spatiotemporal inequities is the definition of critical distances from public services.As an example,to decrease the TT_(max) of TAZs to less than 12 min,their maximum distance to the closest parks should be less than 4 km.The developed approach can be adopted for the accessibility evaluation of the other public services,particularly the health and education centers.展开更多
Objective:This study aimed to identify the distribution and equity trends for general practi-tioners(GPs)in China from 2012 to 2015 and to provide evidence to guide the discipline’s develop-ment of general practice a...Objective:This study aimed to identify the distribution and equity trends for general practi-tioners(GPs)in China from 2012 to 2015 and to provide evidence to guide the discipline’s develop-ment of general practice and for policy-making.Methods:On the basis of data from the National Health Statistics yearbooks,the distribution and equity trends for GPs from 2012 to 2015 were analyzed with the Lorenz curve and Gini coef-ficient as indictors of health equity.Results:From 2012 to 2015 the number of GPs increased at rates ranging from 9.3%to 32.5%,while the number of registered GPs increased at rates ranging from 32.6%to 37.2%.In 2015 the average number of GPs was 1.38 per 10,000 people(among the 31 provinces the highest rate was 3.90 per 10,000 people in Zhejiang and the lowest rate was 0.50 per 10,000 people in Xizang)and 1.98 per 100 km2(among 31 provinces the highest rate was 89.23 per 100 km2 in Shanghai and the lowest rate was 0.01 per 100 km^(2) in Xizang).From 2012 to 2015 the Gini coefficients weighted by population were 0.31,0.29,0.26,and 0.25 respectively,while the Gini coefficients weighted by geographical area were 0.74,0.72,0.72,and 0.72 respectively.Conclusion:The number of GPs increased rapidly in China;however,the proportion of regis-tered GPs was unsatisfactory,and there were inequities among the different provinces.The govern-ment should launch integrated strategies to encourage GP trainees to become registered GPs and optimize the distribution and equity of GPs.展开更多
文摘Purpose:To contribute to the study of networks and graphs.Design/methodology/approach:We apply standard mathematical thinking.Findings:We show that the distance distribution in an undirected network Lorenz majorizes the one of a chain.As a consequence,the average and median distances in any such network are smaller than or equal to those of a chain.Research limitations:We restricted our investigations to undirected,unweighted networks.Practical implications:We are convinced that these results are useful in the study of small worlds and the so-called six degrees of separation property.Originality/value:To the best of our knowledge our research contains new network results,especially those related to frequencies of distances.
文摘Static models of accessibility are usually based on the fixed distance or Average Travel Time(ATT)models.Because of ignoring the traffic as a dynamic process affecting the accessibility through the change of Travel Time(TT),these models lead to unperceived temporal inequities.In contrast to the consideration of the temporal Variation of TT(VTT)in the previous studies,the variation of traffic-related TT and its relations with network distance has not been considered.In this study,relations between VTT and network distance to access urban parks in Tehran megacity has been modeled.Traffic maps at five times of day are used to produce TT maps of Traffic Analysis Zones(TAZs)to their 3-closest parks.Comparison of the Gini coefficients of accessibility show significant inequities of accessibility at different times of day.Relations between the distance,ATT,and TT_(max) are modeled by statistical analysis.Results show both TT and TTmax have significant positive relations with distance and traffic and reach their maximum at 6 p.m.Observation of significant relations between distance,ATT,TT_(max),and VTT provides interesting knowledge for the conversion of temporal measures of equity(TT)to a physical measure of equity(distance).A simple application of these findings for effective management of the spatiotemporal inequities is the definition of critical distances from public services.As an example,to decrease the TT_(max) of TAZs to less than 12 min,their maximum distance to the closest parks should be less than 4 km.The developed approach can be adopted for the accessibility evaluation of the other public services,particularly the health and education centers.
文摘Objective:This study aimed to identify the distribution and equity trends for general practi-tioners(GPs)in China from 2012 to 2015 and to provide evidence to guide the discipline’s develop-ment of general practice and for policy-making.Methods:On the basis of data from the National Health Statistics yearbooks,the distribution and equity trends for GPs from 2012 to 2015 were analyzed with the Lorenz curve and Gini coef-ficient as indictors of health equity.Results:From 2012 to 2015 the number of GPs increased at rates ranging from 9.3%to 32.5%,while the number of registered GPs increased at rates ranging from 32.6%to 37.2%.In 2015 the average number of GPs was 1.38 per 10,000 people(among the 31 provinces the highest rate was 3.90 per 10,000 people in Zhejiang and the lowest rate was 0.50 per 10,000 people in Xizang)and 1.98 per 100 km2(among 31 provinces the highest rate was 89.23 per 100 km2 in Shanghai and the lowest rate was 0.01 per 100 km^(2) in Xizang).From 2012 to 2015 the Gini coefficients weighted by population were 0.31,0.29,0.26,and 0.25 respectively,while the Gini coefficients weighted by geographical area were 0.74,0.72,0.72,and 0.72 respectively.Conclusion:The number of GPs increased rapidly in China;however,the proportion of regis-tered GPs was unsatisfactory,and there were inequities among the different provinces.The govern-ment should launch integrated strategies to encourage GP trainees to become registered GPs and optimize the distribution and equity of GPs.
