A Quantitative Model to Measure the Level of Culture and Tourism Integration Based on a Spatial Perspective: A Case Study of Beijing from 2000 to 2022

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

-  While the description of Beijing and its significance is adequate, consider expanding on why its unique geographical and cultural characteristics make it a particularly relevant case study for this research. Mentioning specific aspects of Beijing’s culture and tourism that will be analyzed could provide a clearer foundation for the study’s relevance.

- The methods section is quite technical and may be difficult for readers unfamiliar with spatial analysis to follow. Simplifying the explanations or providing more context about the kernel density analysis, spatial coupling coordination measurement model, and geographically weighted regression model could make this section more accessible.

- While you’ve explained the kernel density calculation formula, it would be useful to include a rationale for choosing this particular method to analyze cultural and tourism endowments. Explaining how this method suits the objectives of your study could provide readers with a deeper understanding of its application.

- Expanding on how the evaluation index was constructed would strengthen this section. Specifically, discussing how you determined the dimensions of resource endowment, infrastructure, and outputs, and why these are critical for measuring the degree of integration would be insightful. Additionally, elaborating on the entropy method's application and how it contributes to the objectivity of the model would enhance the methodological rigor.

- Offering more comparative insights, especially comparing Beijing's situation with other cities domestically or internationally, could provide a richer context for understanding the significance of your findings.

-  Elaborate on the practical implications of your findings for policymakers, stakeholders in the tourism and cultural sectors, and the broader community. Discussing how this data can inform future urban planning, cultural preservation, and tourism development strategies would add value.

-  Incorporate a comparative analysis with similar studies conducted in other global cities or regions. This comparison could offer insights into how Beijing's approach to integrating culture and tourism compares with global best practices.

Author Response

1.In the introduction, we have added some relevant expressions about the characteristics of cultural tourism in Beijing。

2.We have supplemented the introduction of the above three methods in the Methods section。

3.For the discussion of the applicability of the three methods, we have made the following additions in the methods section：

Nuclear density can directly reflect the distribution characteristics of observation indicators of cultural system and tourism system in each district of Beijing. By observing the nuclear density map, we can directly judge the integration of cultural system and tourism system in each district of Beijing. However, nuclear density analysis is limited to the qualitative discussion of fusion degree, and can not do quantitative analysis. On this basis, by constructing the evaluation index system and using the coupling coordination degree analysis method to analyze the mutual relationship and coordination between the cultural system and the tourism system, the quantitative analysis of the cultural system and the tourism system can be realized, and the shortcomings of the lagging system in the integration process of the cultural system and the tourism system in various districts of Beijing can be further revealed. However, although the coupling coordination degree analysis can compare the integration degree of different regions in Beijing and can also analyze the reasons for the differences to a certain extent, it cannot effectively distinguish the heterogeneity of different districts in Beijing, and the geographical weighted regression model can well solve this problem, which will be crucial for the analysis of the integration degree of culture and tourism and its influencing factors.

4.As for the construction of the index system, we have made the following additions in the method part：

For the construction of the evaluation index system, this paper believes that resource endowment, infrastructure and output are the main contents of the integration of culture and tourism, while management, technology and economic development level are regarded as the influencing factors of the integration of culture and tourism. Cultural resources and tourism resources are interdependent, and the construction of technical facilities of culture and tourism can also promote each other. The output is the key window to examine the integration degree of cultural tourism. On the one hand, it can show the development degree of cultural tourism, and on the other hand, it can obviously observe the shortcomings of cultural tourism. It is helpful for policy makers to formulate corresponding measures in a timely manner.

5.We have added comparisons with other regions in the introduction and policy recommendations in the conclusion

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

The paper titled "A Quantitative Model to Measure the Level of Culture and Tourism Integration Based on a Spatial Perspective: A Case Study of Beijing from 2000 to 2022" presents a comprehensive analysis of the integration of culture and tourism in Beijing over a specific time period. While the paper offers valuable insights into the methodology and findings, there are several aspects that need improvement:

Introduction: It would benefit from explicitly stating what the paper aims to achieve.

Literature Review: The literature review provides some context for the study but could be strengthened by discussing previous research on culture and tourism integration in other regions or countries. This would provide a broader understanding of the topic and better contextualize the study.

Methodology: The section lacks justification for the selection of specific methods and models. While the paper mentions the sources of socioeconomic, cultural heritage, and spatial data, it does not provide details on data collection methods or potential limitations of the data.

Results: The section lacks clarity in organization, making it challenging for readers to follow the flow of information. It would benefit from clearer subheadings and a more structured approach to presenting the results. The analysis could be strengthened by providing more interpretation of the data presented in the figures and tables. For example, explaining the significance of specific trends or patterns observed in the spatial distribution of cultural and tourism resources would enhance the understanding of the results. The section discusses various aspects of culture and tourism integration, such as the level of integration at the city and district levels, coupling coordination patterns, and factors influencing integration. However, there is limited integration of these findings into a coherent narrative. Connecting the different findings and explaining their implications for culture and tourism development in Beijing would enhance the overall coherence of the section.

Discussion: It lacks depth in analyzing the spatial distribution of cultural and tourism endowments in Beijing, focusing primarily on describing the distribution rather than exploring underlying factors. Also, the paper mentions the spatial differences in the distribution of cultural and tourism endowments across various districts, noting concentrations in core areas like Dongcheng, Xicheng, Haidian, and Chaoyang districts, with relatively lower endowments in Fengtai and Shijingshan districts. Additionally, it discusses the increasing integration of culture and tourism in rural areas like Yanqing, Huairou, and Mentougou districts, albeit with room for further development. Temporally, the paper acknowledges a gradual upward trend in the integration of culture and tourism from 2000 to 2022, albeit with interruptions due to events like the COVID-19 pandemic. However, the analysis of spatial and temporal concentrations appears to lack exploration of underlying factors driving these patterns. I recommend to include the following paper in the reference: Fernandes, P. O., Nunes, A. M., Veloso, C. M., Santos, E., Ferreira, F. A., & Fonseca, M. J. (2019). Spatial and temporal concentration of tourism supply and demand in Northern Portugal. Application of the Herfindahl-Hirschman index. In Advances in Tourism, Technology and Smart Systems: Proceedings of ICOTTS 2019 (pp. 263-273). Singapore: Springer Singapore.

There is a missed opportunity to discuss the implications of this uneven distribution on regional development and tourism planning strategies. While it briefly compares strengths and weaknesses of different districts, a more comprehensive analysis is needed to provide insights into potential integration strategies. Additionally, the discussion lacks contextualization by not exploring historical, socio-economic, and political factors influencing cultural and tourism resource development. It also superficially examines factors influencing integration, such as economic development, tourism and cultural outputs, policy support, technology, and consumption levels, without thoroughly analyzing their interactions. A deeper analysis of these factors is necessary for a nuanced understanding of integration challenges and opportunities.

Parte superior do formulário

 

Conclusion: The conclusion largely reiterates the findings presented in the discussion section without offering novel insights or recommendations. It misses an opportunity to synthesize the key findings and propose actionable recommendations for policymakers and stakeholders. While the conclusion briefly mentions the proposed spatial quantification method for measuring the degree of culture and tourism integration, it does not reflect on the limitations or strengths of the methodology. The limitations and outlook section offers generic statements without specific details on the challenges encountered during the research process or concrete suggestions for future research directions.

Author Response

Introduction: It would benefit from explicitly stating what the paper aims to achieve.

R: We modify the summary to read as follows:

The integration of culture and tourism has become an important factors in the development of the cultural tourism industry, and a quantitative measure of the degree of integration is important for understanding and promoting the high-quality development of the global cultural tourism industry. This study aims to put forward a comprehensive analysis model to show the development trend of cultural and tourism integration, measure the degree of cultural and tourism integration, and analyze the factors affecting the regional heterogeneity of cultural and tourism integration. By using the spatial quantification method of entropy, spatial coupling coordination degree model and geographical weighting model, this paper analyzes the effect and influencing factors of cultural and tourism integration in various districts and counties in Beijing. The results show that the cultural tourism resource endowment of Beijing presents an upward trend and a gradual spillover trend, with obvious spillover to the east and north. The effect of district integration in Beijing has gradually weakened from the city center to the outside, but there is still a serious phenomenon of two levels of differentiation. Factors such as economic development level, tourism output, cultural output, policy support and consumption level have spatial heterogeneity on the effect of cultural and tourism integration in each district of Beijing, but the degree of influence is small.

Literature Review: The literature review provides some context for the study but could be strengthened by discussing previous research on culture and tourism integration in other regions or countries. This would provide a broader understanding of the topic and better contextualize the study.

R: R: We have added the following to the introduction:

Taking Jiangsu Province as the research area, Weili Shen et al. built a coupling sensitivity and perception model of culture and tourism system, proposed that with the passage of time, the comprehensive development level of the two systems is con-stantly improving, and pointed out that the spatial distribution of cultural tourism system in Jiangsu Province has obvious spatial dependence and spillover [11]. Guoqiang Xiong et al. used the gray measurement model to study the complementarity of the integration and development of the cultural industry and the tourism industry, and believed that the level of economic integration in China was low and the overall trend was slowly rising.[21] S. Vujovi et al., taking Vojvodina as a sample, studied the economic effects of cultural heritage on the development environment of agritourism, and concluded that cultural heritage has obvious promoting effect on tourism, especially agritourism.[22]

Methodology: The section lacks justification for the selection of specific methods and models. While the paper mentions the sources of socioeconomic, cultural heritage, and spatial data, it does not provide details on data collection methods or potential limitations of the data.

R: We have added the following to the Limitations and outlook:

In this study, when constructing the three-level evaluation index system, the availability of major data from statistical yearbook and related channels was considered. There would be differences in the selection of municipal and district-level indicators, but the first-level indicators and second-level indicators would not change. In subsequent studies, the third-level indicators could be reasonably replaced based on the second-level indicators according to the characteristics of the study region and da-ta.

Results: The section lacks clarity in organization, making it challenging for readers to follow the flow of information. It would benefit from clearer subheadings and a more structured approach to presenting the results. The analysis could be strengthened by providing more interpretation of the data presented in the figures and tables. For example, explaining the significance of specific trends or patterns observed in the spatial distribution of cultural and tourism resources would enhance the understanding of the results. The section discusses various aspects of culture and tourism integration, such as the level of integration at the city and district levels, coupling coordination patterns, and factors influencing integration. However, there is limited integration of these findings into a coherent narrative. Connecting the different findings and explaining their implications for culture and tourism development in Beijing would enhance the overall coherence of the section.

R：We have added at the beginning of the paragraph relevant concluding statements that link the preceding to the following

Discussion: It lacks depth in analyzing the spatial distribution of cultural and tourism endowments in Beijing, focusing primarily on describing the distribution rather than exploring underlying factors. Also, the paper mentions the spatial differences in the distribution of cultural and tourism endowments across various districts, noting concentrations in core areas like Dongcheng, Xicheng, Haidian, and Chaoyang districts, with relatively lower endowments in Fengtai and Shijingshan districts. Additionally, it discusses the increasing integration of culture and tourism in rural areas like Yanqing, Huairou, and Mentougou districts, albeit with room for further development. Temporally, the paper acknowledges a gradual upward trend in the integration of culture and tourism from 2000 to 2022, albeit with interruptions due to events like the COVID-19 pandemic. However, the analysis of spatial and temporal concentrations appears to lack exploration of underlying factors driving these patterns. I recommend to include the following paper in the reference: Fernandes, P. O., Nunes, A. M., Veloso, C. M., Santos, E., Ferreira, F. A., & Fonseca, M. J. (2019). Spatial and temporal concentration of tourism supply and demand in Northern Portugal. Application of the Herfindahl-Hirschman index. In Advances in Tourism, Technology and Smart Systems: Proceedings of ICOTTS 2019 (pp. 263-273). Singapore: Springer Singapore.

There is a missed opportunity to discuss the implications of this uneven distribution on regional development and tourism planning strategies. While it briefly compares strengths and weaknesses of different districts, a more comprehensive analysis is needed to provide insights into potential integration strategies. Additionally, the discussion lacks contextualization by not exploring historical, socio-economic, and political factors influencing cultural and tourism resource development. It also superficially examines factors influencing integration, such as economic development, tourism and cultural outputs, policy support, technology, and consumption levels, without thoroughly analyzing their interactions. A deeper analysis of these factors is necessary for a nuanced understanding of integration challenges and opportunities.

 R：Our research mainly focuses on the feasibility of the method, and the extension of the conclusion analysis can be many aspects. Through the comparison with the relevant studies, the conclusion of our study is basically consistent with the results of previous studies.

Conclusion: The conclusion largely reiterates the findings presented in the discussion section without offering novel insights or recommendations. It misses an opportunity to synthesize the key findings and propose actionable recommendations for policymakers and stakeholders. While the conclusion briefly mentions the proposed spatial quantification method for measuring the degree of culture and tourism integration, it does not reflect on the limitations or strengths of the methodology. The limitations and outlook section offers generic statements without specific details on the challenges encountered during the research process or concrete suggestions for future research directions.

R：We add the following to the conclusion：

For Beijing Municipal Government, on the one hand, it should strengthen the regional spillover effect of cultural tourism resources, speed up the construction of infrastructure, especially cultural infrastructure, and enhance the attraction of cultural tourism. On the other hand, we should strengthen the construction of cultural tourism in the outer suburbs, dig deep into the cultural characteristics of the resources in the outer suburbs, develop and utilize them reasonably, strengthen the construction of transportation facilities and other infrastructure, and improve the attractiveness of cultural tourism. For the Beijing municipal government, it is necessary to clearly understand the advantages and disadvantages of the development of cultural tourism industry in the region. Although Dongcheng, Xicheng, Haidian and Chaoyang districts have rich cultural tourism resources, they also have high living costs. Other regions, of course, have large administrative areas and relatively low living costs, but the distribution of cultural tourism resources is relatively scattered. With high transportation costs. Therefore, the district-level government should strengthen the use of superior resources, rational use of the advantages of the surrounding areas, and improve the attractiveness of cultural tourism.

The above research conclusions are basically consistent with the research conclusions of other scholars on cultural tourism in Beijing.[60-61] It can be seen that the comprehensive analysis method proposed in this study can effectively analyze the effect of regional cultural tourism integration and the heterogeneity of different influencing factors on the degree of cultural tourism integration in different regions, and can be used as an effective analysis tool for policy makers.

Reviewer 3 Report

Comments and Suggestions for Authors

Dear Authors,

The proposed study has potential, the topic is interesting, but the article has many weaknesses.

The Abstract is much too detailed. The results should be presented in a more succinct form.

The concepts and ideas that led to this paper are not explained, they are only nominated. For example:

- line 58: infrastructure and cultural outputs -  clarification on these concepts is needed.

- line 63: the differentiation between tangible and intangible cultural resources is unclear, and the inclusion of Antarctic culture in this enumeration is unnatural for what you propose to analyze.

- lines 77-78: a series of concepts have been introduced, such as secondary information, evaluation index, integration subject, integration resources, and integration benefits. All of these elements must be explained in the context of proposed analysis. 

Also, by citing previous articles, you need to highlight the veracity and opportunity of using the methods in the analysis of integration between culture and tourism.

The word relatively is used very often, which leads to uncertainty regarding the objectivity of the results obtained. Even the proposed entropy method is presented as relatively objective.

Line 142: you mention the concepts: resource endowment, infrastructure, and outputs, without providing any details regarding their content for the analyzed geographical area. They are later highlighted in Tables 1 and 2, but brief theoretical comments related to these elements are absolutely necessary.

Explanations regarding the number and content of the secondary indicators, why these indicators were used and what is their relevance for the purpose of the study are important. The same comment for all tertiary indicators.

In conclusion, the Introduction section must be completely reformulated, mainly with the idea of including information specific to a non-existent section in your paper, e.g. Theoretical background.

In the Discussion section, comparisons between the results obtained in your study with other studies on the same topic are inconclusive. Also, the validation of the analysis methods used to obtain the desired results by comparing them with other studies is missing.

Author Response

1.

Our summary is revised as follows：

The integration of culture and tourism has become an important factors in the development of the cultural tourism industry, and a quantitative measure of the degree of integration is important for understanding and promoting the high-quality development of the global cultural tourism industry. This study aims to put forward a comprehensive analysis model to show the development trend of cultural and tourism integration, measure the degree of cultural and tourism integration, and analyze the factors affecting the regional heterogeneity of cultural and tourism integration. By using the spatial quantification method of entropy, spatial coupling coordination degree model and geographical weighting model, this paper analyzes the effect and influencing factors of cultural and tourism integration in various districts and counties in Beijing. The results show that the cultural tourism resource endowment of Beijing presents an upward trend and a gradual spillover trend, with obvious spillover to the east and north. The effect of district integration in Beijing has gradually weakened from the city center to the outside, but there is still a serious phenomenon of two levels of differentiation. Factors such as economic development level, tourism output, cultural output, policy support and consumption level have spatial heterogeneity on the effect of cultural and tourism integration in each district of Beijing, but the degree of influence is small.

2.

Our introduction is revised as follows

The positive effect of the tourism industry on economic growth has been extensively demonstrated^[1-3]. In recent years, cultural tourism has become the main growth area of the tourism industry, and thus researchers are paying increasing attention to cultural tourism^[4-5]. Therefore, the Chinese government has introduced a series of policies promoting the integration of the cultural and tourism industries. Some scholars have analyzed the level of integration of the two industries^[6-8], but have ignored a type of important cultural resources beyond the cultural industry^[4]. Cultural tourism is essentially a specialized market segment within the tourism industry^[9-10], the integration of culture and tourism is mainly reflected in three aspects: resource endowment, infrastructure and output. Resource endowment is the foundation of the integration of culture and tourism, and infrastructure is the guarantee of the integration of culture and tourism, and it is the efforts made by regional subjects to realize the development of cultural tourism. In terms of culture, it is represented by the number of cultural units and universities, and in terms of tourism, it is represented by environmental quality and traffic conditions. The output is the embodiment of the integration effect of culture and tourism, which is represented by the number of visitors to cultural units in culture and tourism income in tourism, While some scholars have considered the integration of cultural resources and the tourism industry, they have failed to consider the impact of infrastructure and cultural outputs on the degree of integration^[11]. Attempts to measure the effectiveness of cultural tourism integration in the absence of cultural infrastructure and its outputs are likely to result in misleading conclusions. Thus, there is a lack of a systematic method for measuring the degree of integration of culture and tourism.

Given the trend toward increasingly diversified and fragmented development of the cultural tourism industry^[6], The forms of cultural and tourism integration are becoming more and more abundant, and the number of cultural tourism for intangible cultural heritage is also increasing^[4,12]. On the one hand, studies on the development of traditional cultural resources such as metropolitan suburbs^[13], traditional villages^[14], tea culture^[15-16], and religious culture^[17] have begun to attract increasing attention. On the other hand, studies on emerging cultural resources such as performing culture^[18]，food culture^[19], medical culture^[20], and creative culture^[4] are also gaining increasing attention.

Taking Jiangsu Province as the research area, Weili Shen et al. built a coupling sensitivity and perception model of culture and tourism system, proposed that with the passage of time, the comprehensive development level of the two systems is constantly improving, and pointed out that the spatial distribution of cultural tourism system in Jiangsu Province has obvious spatial dependence and spillover ^[11]. Guoqiang Xiong et al. used the gray measurement model to study the complementarity of the integration and development of the cultural industry and the tourism industry, and believed that the level of economic integration in China was low and the overall trend was slowly rising.^[21] S. Vujovi et al., taking Vojvodina as a sample, studied the economic effects of cultural heritage on the development environment of agri-tourism, and concluded that cultural heritage has obvious promoting effect on tourism, especially agri-tourism.^[22]

Measuring the degree of culture and tourism integration has the potential to contribute to the sustainable development of global cultural tourism resources and promote high-quality economic development. Thus, numerous scholars have attempted to measure it using the coupling coordination model^[23-25]. The basis of the coupling coordination model is the establishment of an evaluation index based on the focus of the study and data availability. The evaluation index system is usually set as three levels, and the first level index is divided into two dimensions: culture and tourism. Regarding the secondary indicators, various dimensions of the evaluation index are constructed from different perspectives such as the integration subject, integration resources, and integration benefits^[23-25]. Most existing coupling coordination models have been combined with the analytic hierarchy process (AHP)^[26-27], which is often limited by the ability and subjectivity of the researchers. Compared with the AHP, the entropy method is relatively objective. When combined with spatial analysis methods such as the kernel density method and the geographic weighted model method, this can render the coupling coordination model more intuitive and spatially visualizable^[28-29].

Moreover, geographic information system(GIS) technology can be applied to the integration of multiple disciplines and innovative research methods. For instance, we have used spatialization and interdisciplinary methods to complete the mapping of priority global wetland conservation areas^[30] and track the sustainable tourism development process in 13 cities in the Beijing–Tianjin–Hebei urban agglomeration^[31]. Based on the spatialization perspective, in this study, we propose a spatial quantification method that combines the entropy method, the spatial coupling coordination model, and the geographic weighting model. We explore the effectiveness of and factors influencing the integration of culture and tourism in various districts and counties of Beijing.

As the center of politics, culture, international exchanges and scientific and technological innovation in China, Beijing has abundant resources of ancient capital culture, Red culture, folk culture and innovative culture, which is a representative sample for studying the integration of culture and tourism. Therefore, this paper takes Beijing as an example to conduct an empirical study on the quantitative methods of cultural and tourism integration.

3.

In the conclusion part, we added the comparison between our research results and those of previous studies, as follows：

The above research conclusions are basically consistent with the research conclusions of other scholars on cultural tourism in Beijing.^[60-61] It can be seen that the comprehensive analysis method proposed in this study can effectively analyze the effect of regional cultural tourism integration and the heterogeneity of different influencing factors on the degree of cultural tourism integration in different regions, and can be used as an effective analysis tool for policy makers.

 

Reviewer 4 Report

Comments and Suggestions for Authors

In my opinion, the paper requires corrections and additions.

The purpose of the paper should be clearly stated (preferably in a separate paragraph of text).In my opinion, the abstract of the paper requires additions (it lacks a purpose and the results and conclusions are very general).

The paper does not indicate why the years 2015, 2018 and 2021 were selected for research. It is worth explaining.

The research results presented are sometimes unclear (e.g. Figure 2). The authors should also refer to the results of other studies.

In the summary, the authors write that "… model that is proposed in this study could be a useful tool...". The question is what to do to make the model useful not could be useful? Generally, in my opinion, this part (Conclusion) lacks specific conclusions from the research.

Author Response

1.We modified and simplified the description of the abstract, and clearly explained the purpose of the research in the abstract。

2.In the part of methods, we added the reasons for choosing 2015,2108 and 2021, the third and third years, one is to reflect the situation of development changes, but according to the availability of data

3.When constructing the index system, the availability of relevant data should be considered, but the first-level index and the second-level index should not be changed, and the third-level index should be determined by the specific situation. We added the corresponding expression in the last discussion

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The methodology section is complex. It would be beneficial to break down the explanation of the spatial quantification method into clearer sub-sections or step-by-step processes. The spatial coupling coordination model, and the geographic weighting model more clearly.

It would be insightful if the paper could compare the proposed spatial quantification method with other existing methods of quantifying culture and tourism integration. This comparison could help highlight the advantages or unique aspects of your approach.

Expanding the discussion on the policy implications of your findings could make the study more impactful. Detailed suggestions on how policymakers can utilize your findings to promote cultural tourism, especially in a post-pandemic world, would be particularly relevant.

Author Response

1.We readjust the statement logic of the Spatial coupling coordination measurement model and deduce the calculation process step by step.

2.In the introduction part, we have supplemented the research of relevant scholars. Other scholars have made important observations on spatial layout and its influencing factors, while we focused on providing analysis methods. Therefore, other scholars hardly used entropy weight method and geographical weighted regression model for analysis at the same time.

3.In the conclusion part, we have added relevant suggestions for decision makers. This paper focuses on the use of methods and the scientific discussion of methods, and the analysis of method conclusions focuses on the verification of conclusions with other researchers. We have added this part in the result part.

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript has improved.

Author Response

Thanks, we have revised some statements in the article

Reviewer 3 Report

Comments and Suggestions for Authors

The modified version of the paper meets the criteria to be published.

Author Response

Thanks a lot

Reviewer 4 Report

Comments and Suggestions for Authors

In my opinion, the Authors made the necessary corrections to the paper.

The Authors commented quite generally on my comments in Authors' Responses to Reviewer's Comments, and did not indicate in detail the changes introduced in the paper. Nevertheless, in my opinion, the article can be published after minor changes, mainly editorial and linguistic ones.

Author Response

Thanks a lot.

We have revised some statements in the article.