AIM To develop predictive markers in blood for colorectal cancer liver metastasis.METHODS Twenty colorectal cancer patients were selected and divided into two groups. Group A consisted of 10 patients whose pathologica...AIM To develop predictive markers in blood for colorectal cancer liver metastasis.METHODS Twenty colorectal cancer patients were selected and divided into two groups. Group A consisted of 10 patients whose pathological TNM stage was ⅢC(T3-4N2M0), while another 10 patients with synchronous liver metastasis(TNM stage Ⅳ) were recruited for group B. During the surgical procedure, a 10-ml drainage vein(DV) blood sample was obtained from the DV of the tumor-bearing segment prior to the ligation of the DV. At the same time, a 10-ml peripheral vein(PV) blood sample was collected via peripheral venipuncture. The serum levels of 24 molecules that are potentially involved in the mechanism of liver metastasis in both DV blood and PV blood were analyzed by using high-throughput enzyme-linked immunosorbent assay technology.RESULTS Univariate analysis revealed that platelet-derivedgrowth factor AA(PDGFAA) in DV blood(d PDGFAA)(P = 0.001), PDGFAA in PV blood(p PDGFAA)(P = 0.007), and human epidermal growth factor receptor-2 in PV blood(p HER2)(P = 0.001), p MMP7(P = 0.028), pR ANTES(P = 0.013), and pE GF(P = 0.007) were significantly correlated with synchronous liver metastasis. Multivariate analysis identified d PDGFAA(HR = 1.001, P = 0.033) and p HER2(HR = 1.003, P = 0.019) as independent predictive factors for synchronous liver metastasis. Besides, high peripheral HER2 level may also be a risk factor for metachronous liver metastasis, although the difference did not reach statistical significance(P = 0.06). Significant correlations were found between paired DV and PV blood levels for PDGFAA(r = 0.794, P < 0.001), but not for HER2(r = 0.189, P = 0.424).CONCLUSION PDGFAA in tumor drainage and HER2 in PV blood may be useful predictive factors for synchronous liver metastasis of colorectal cancer.展开更多
A small number of copepod species have adapted to an existence in the extreme habitat of hypersaline water. 13 copepod species have been recorded in the hypersaline waters of Crimea (the largest peninsula in the Blac...A small number of copepod species have adapted to an existence in the extreme habitat of hypersaline water. 13 copepod species have been recorded in the hypersaline waters of Crimea (the largest peninsula in the Black Sea with over 50 hypersaline lakes). Summarizing our own and literal_re data, the author concludes that the Crimean extreme environment is not an exception: copepod species dwell in hypersaline waters worldwide. There are at least 26 copepod species around the world living at salinity above 100; among them 12 species are found at salinity higher than 200. In the Crimea Cletocamptus retrogressus is found at salinity 360×10^-3 (with a density of 1 320 individuals/m^3) and Arctodiaptomus salinus at salinity 300×10^-3 (with a density of 343 individuals/m^3). Those species are probably the most halotolerant copepod species in the world. High halotolerance of osmoconforming copepods may be explained by exoosmolyte consumption, mainly with food. High tolerance to many factors in adults, availability of resting stages, and an opportunity of long-distance transportation of resting stages by birds and/or winds are responsible for the wide geographic distribution of these halophilic copepods.展开更多
The full review of The International Convention on Standards of Training, Certification and Watch keeping for Seafarers (the STCW Convention) has been accomplished by International Maritime Organization (IMO) and ...The full review of The International Convention on Standards of Training, Certification and Watch keeping for Seafarers (the STCW Convention) has been accomplished by International Maritime Organization (IMO) and the new amendment, which is also named as Manila amendment, has been effective since 2012, with a transitional period of 2012-2017. Based on the system engineering context consisting of "Human, Machine and Environment", human factors at sea, i.e., those factors relevant to the seafarers, are consistently underlined. STCW convention is the unique but systematic international maritime legislation looking after the "professional competency standards" of seafarers. The amendment thereto is of great significance for the Maritime Education and Training (MET) systems, which should be fully understood so as to respond to it effectively. The paper analyzes major impacts brought by the amendment, with purposes to raise recommendations for MET systems to implement the amendment effectively.展开更多
It has been classed 856 species of the mollusks which belong to 120 families and five classes living in western coast of the Tonkin Gulf. The class Gastropod was the most abundant, with 449 species, the Bivalve with 3...It has been classed 856 species of the mollusks which belong to 120 families and five classes living in western coast of the Tonkin Gulf. The class Gastropod was the most abundant, with 449 species, the Bivalve with 368 species, the Scaphopoda with 10 species, the Cephalopods with 19 species and the Amphineura with eight species. Standing stock was estimated about 366,749 tons, that annually caught 80,000 tons. The causes of the resource depletion were human and natural, but the human factors played a key role. The fundamental orientations for developing the resources include: exploiting during harvest seasons, planning suitable aquaculture, moderate exploitation so the resources can restore themselves, combining exploitation and conservation.展开更多
This paper is a summary of the studies done on the importance of the cognitive styles especially reflectivity/impulsivity on the process of language acquisition. It discusses the importance of this cognitive style as ...This paper is a summary of the studies done on the importance of the cognitive styles especially reflectivity/impulsivity on the process of language acquisition. It discusses the importance of this cognitive style as an important factor on the effectiveness of awareness raising activities. In the previous studies, the importance of awareness raising has been found as an effective and facilitating factor in the process of the L2 (second language) acquisition, but the effect of different individual factors on its being usefulness has not been focused on; therefore, this study is an attempt to review and explore the importance of one of the individual factors, i.e., being reflective/impulsive cognitive style on the effectiveness of awareness raising activities. It is gathered that learners with different cognitive styles (being reflective/impulsive) react differently to the awareness giving activities, and the study tries to emphasize the importance of this factor on the usefulness of awareness raising and emphasizes the fact that in the field of awareness giving this factor should be attached impotence and accounted for as an effective factor.展开更多
The objectives of the research are to determine the important factors and the performance factors of the attributes in selecting venues (particularly convention hotels and convention centers) through investigating t...The objectives of the research are to determine the important factors and the performance factors of the attributes in selecting venues (particularly convention hotels and convention centers) through investigating the meeting planners' set of needs and to identify factors and attributes relating to the venue marketing mix for MICE industry in Thailand. This paper has applied the hospitality and the tourism marketing mixes that are important to the MICE destination selection (particularly venues) for creating a new venue marketing mix. Therefore, the study is based on the importance levels of venue selection through each marketing mix factors including all attributes in the meeting planners' perspectives on behalf of their organizations, which will be able to reflect a set of their real needs that could bring about development of a venue marketing mix model that exclusively accommodates MICE organizers. The data was collected using self-administered questionnaires from 229 meeting planners. Statistically significant determinants of the meeting planners' overall importance levels indicated that in all of the 8 marketing mix factors (68 attributes), the people factor was perceived to be the most important factor. The package factor was perceived to have a moderate level of importance. The other factors perceived to be important included Product, Price, Place, Promotion, Physical evidence and Process. It is also found from the factor analysis that the new venue marketing mix contained 8 marketing mix factors with 61 attributes for venue business in Thailand. It is recommended from the research findings that venue management be more concerned with and focus on the attributes of the people factor.展开更多
Internal auditors hold a unique position in their organizations to prevent, deter, and detect corporate wrongdoings. However, the role of this profession in investigating their ethical decision-making behaviors toward...Internal auditors hold a unique position in their organizations to prevent, deter, and detect corporate wrongdoings. However, the role of this profession in investigating their ethical decision-making behaviors towards internal whistle-blowing intentions has been very often neglected. Furthermore, although extensive researches have been undertaken on the issue of whistle blowing globally, empirical studies on this area are still scarce in Malaysia. This paper examines internal whistle-blowing intentions among internal auditors in Malaysia by utilizing three independent vignettes. A mail survey was conducted to investigate demographic and individual factors that could influence internal auditors' ethical decision-making processes. The likelihood for internal whistle-blowing intentions was significant among internal auditors' ethical judgments for all the three vignettes. Demographic factors (gender, age, and tenure) and other individual factors (locus of control and organizational commitment) failed to explain the likelihood of internal auditors' internal whistle-blowing intentions. Findings should aid researchers in their understandings of the determinants of individuals' internal whistle-blowing behaviors.展开更多
AIM:To investigate effects of hepatotropic growth factors on radical production in rat hepatocytes during sepsis.METHODS:Rat hepatocytes,isolated by collagenase perfusion,were incubated with a lipopolysaccharide(LPS)-...AIM:To investigate effects of hepatotropic growth factors on radical production in rat hepatocytes during sepsis.METHODS:Rat hepatocytes,isolated by collagenase perfusion,were incubated with a lipopolysaccharide(LPS)-containing cytokine mixture of interleukin-1β,tumor necrosis factor-α and interferon-γ to simulate sepsis and either co-incubated or pre-incubated with hepatotropic growth factors,e.g.hepatocyte growth factor,epidermal growth factor and/or transforming growth factor-α.Cells were analyzed for glutathione levels.Culture supernatants were assayed for produc-tion of reactive oxygen intermediates(ROIs) as well as NO2-,NO3-and S-nitrosothiols.To determine cellular damage,release of aspartate aminotransferase(AST) into the culture medium was analyzed.Activation of nuclear factor(NF)-κB was measured by electrophoretic mobility shift assay.RESULTS:Rat hepatocytes treated with the LPS-containing cytokine mixture showed a significant increase in ROI and nitrogen oxide intermediate formation.AST leakage was not significantly increased in cells treated with the LPS-containing cytokine mixture,independent of growth-factor co-stimulation.However,pretreatment with growth factors significantly reduced AST leakage and ROI formation while increasing cellular glutathione.Application of growth factors did not result in increased NF-κB activation.Pretreatment with growth factors further increased formation of NO2-,NO3-and S-nitrosothiols in hepatocytes stimulated with LPS-containing cytokine mixture.Thus,we propose that,together with an increase in glutathione increased NO2-,NO3-formation might shift their metabolism towards non-toxic products.CONCLUSION:Our data suggest that hepatotropic growth factors positively influence sepsis-induced hepatocellular injury by reducing cytotoxic ROI formation via induction of the cellular protective antioxidative systems.展开更多
The interactive effects of natural and human factors on ecosystems have been well studied, and the quantitative assessment of large-scale ecological vulnerability caused by natural and human factors is now one of the ...The interactive effects of natural and human factors on ecosystems have been well studied, and the quantitative assessment of large-scale ecological vulnerability caused by natural and human factors is now one of the most active topics in the ifeld. Taking the Guangxi Xijiang River Economic Belt in southwest China (GXEB) as a case study, we assess ecological vulnerability based on the Vulnerability Scoping Diagram (VSD) model. The indices system is decomposed into three sub objects, ten elements and 25 indicators layer by layer, which included factors from both natural and human ifelds. Results indicate that zones with lower, middle-lower, middle, middle-higher and higher vulnerability account for 11.31%, 22.63%, 27.60%, 24.39%, and 14.07%, respectively. The western and eastern parts of GXEB are more vulnerable than the central part and the mountain and urban areas are of higher vulnerability than the basins and river valleys. Compared with a vulnerability assessment based on natural factors only, it is concluded that human activities indeed cause the transition from naturally stable zones to vulnerable zones. The nature-dominated vulnerable zones are different with human-dominated ones in size and distribution, the latter being smaller, more scattered and distributed in urban areas and their surroundings. About 53%of total construction land is distributed in zones with middle and middle-higher ecological vulnerability;less vulnerable zones should attract construction in the future. Relevant suggestions are proposed on how to reduce vulnerability according to inducing factors. The VSD model has a signiifcant advantage in the quantitative evaluation of ecological vulnerability, but is insufficient to distinguish nature- or human-dominated vulnerability quantitatively.展开更多
Terrain plays a key role in landscape pattern formation, particularly in the transition zones from mountains to plains.Exploring the relationships between terrain characteristics and landscape types in terrain-complex...Terrain plays a key role in landscape pattern formation, particularly in the transition zones from mountains to plains.Exploring the relationships between terrain characteristics and landscape types in terrain-complex areas can help reveal the mechanisms underlying the relationships. In this study, Qihe River Basin, situated in the transition zone from the Taihang Mountains to the North-China Plain, was selected as a case study area. First, the spatial variations in the relief amplitudes(i.e.,high-amplitude terrain undulations) were analyzed. Second, the effects of relief amplitudes on the landscape patterns were indepth investigated from the perspectives of both landscape types and landscape indices. Finally, a logistic regression model was employed to examine the relationships between the landscape patterns and the influencing factors(natural and human) at different relief amplitudes. The results show that with increasing relief amplitude, anthropogenic landscapes gradually give in to natral landscapes. Specifically, human factors normally dominate the gentle areas(e.g., flat areas) in influencing the distribution of landscape types, and natural factors normally dominate the highly-undulating areas(e.g., moderate relief areas). As for the intermediately undulating areas(i.e.,medium relief amplitudes), a combined influence of natural and human factors result in the highest varieties of landscape types. The results also show that in micro-relief areas and small relief areas where natural factors and human factors are more or less equally active,landscape types are affected by a combination of natural and human factors.The combination leads to a high fragmentation and a high diversity of landscape patterns. It seems that appropriate human interferences in these areas can be conducive to enhancing landscape diversity and that inappropriate human interferences can aggravate the problems of landscape fragmentation.展开更多
Geography requires a comprehensive understanding of both natural and human factors,as well as their interactions.Due to the complexity and multiplicity of geographic problems,various theories and methods for geographi...Geography requires a comprehensive understanding of both natural and human factors,as well as their interactions.Due to the complexity and multiplicity of geographic problems,various theories and methods for geographic modelling and simulation have been proposed.Currently,geography has entered an era in which quantitative analysis and modelling are essential for understanding the mechanisms of geographic processes.As the basic idea of quantitative spatial analysis,the specified space often needs to be partitioned by a series of small computational units(cells),i.e.,grids.Thus,there is a close relationship between the grids and geographic modelling.This article reviews the mainstream and typical grids used for modelling and simulation.In addition to classification,the derived theories and technologies,including grid generation methods,data organization strategies,multi-dimensional querying methods,and grid adaptation techniques,are discussed.For integrated geographic simulation to explore comprehensive geographic problems,we argued that it is reasonable to build bridges among different types of grids(e.g.,transformation strategies),and more powerful grids that can support multi-type of numerical computation are urgently needed.展开更多
基金Supported by the Scientific research Fund of Peking University Cancer Hospital,No.2013 zizhu-8
文摘AIM To develop predictive markers in blood for colorectal cancer liver metastasis.METHODS Twenty colorectal cancer patients were selected and divided into two groups. Group A consisted of 10 patients whose pathological TNM stage was ⅢC(T3-4N2M0), while another 10 patients with synchronous liver metastasis(TNM stage Ⅳ) were recruited for group B. During the surgical procedure, a 10-ml drainage vein(DV) blood sample was obtained from the DV of the tumor-bearing segment prior to the ligation of the DV. At the same time, a 10-ml peripheral vein(PV) blood sample was collected via peripheral venipuncture. The serum levels of 24 molecules that are potentially involved in the mechanism of liver metastasis in both DV blood and PV blood were analyzed by using high-throughput enzyme-linked immunosorbent assay technology.RESULTS Univariate analysis revealed that platelet-derivedgrowth factor AA(PDGFAA) in DV blood(d PDGFAA)(P = 0.001), PDGFAA in PV blood(p PDGFAA)(P = 0.007), and human epidermal growth factor receptor-2 in PV blood(p HER2)(P = 0.001), p MMP7(P = 0.028), pR ANTES(P = 0.013), and pE GF(P = 0.007) were significantly correlated with synchronous liver metastasis. Multivariate analysis identified d PDGFAA(HR = 1.001, P = 0.033) and p HER2(HR = 1.003, P = 0.019) as independent predictive factors for synchronous liver metastasis. Besides, high peripheral HER2 level may also be a risk factor for metachronous liver metastasis, although the difference did not reach statistical significance(P = 0.06). Significant correlations were found between paired DV and PV blood levels for PDGFAA(r = 0.794, P < 0.001), but not for HER2(r = 0.189, P = 0.424).CONCLUSION PDGFAA in tumor drainage and HER2 in PV blood may be useful predictive factors for synchronous liver metastasis of colorectal cancer.
文摘A small number of copepod species have adapted to an existence in the extreme habitat of hypersaline water. 13 copepod species have been recorded in the hypersaline waters of Crimea (the largest peninsula in the Black Sea with over 50 hypersaline lakes). Summarizing our own and literal_re data, the author concludes that the Crimean extreme environment is not an exception: copepod species dwell in hypersaline waters worldwide. There are at least 26 copepod species around the world living at salinity above 100; among them 12 species are found at salinity higher than 200. In the Crimea Cletocamptus retrogressus is found at salinity 360×10^-3 (with a density of 1 320 individuals/m^3) and Arctodiaptomus salinus at salinity 300×10^-3 (with a density of 343 individuals/m^3). Those species are probably the most halotolerant copepod species in the world. High halotolerance of osmoconforming copepods may be explained by exoosmolyte consumption, mainly with food. High tolerance to many factors in adults, availability of resting stages, and an opportunity of long-distance transportation of resting stages by birds and/or winds are responsible for the wide geographic distribution of these halophilic copepods.
文摘The full review of The International Convention on Standards of Training, Certification and Watch keeping for Seafarers (the STCW Convention) has been accomplished by International Maritime Organization (IMO) and the new amendment, which is also named as Manila amendment, has been effective since 2012, with a transitional period of 2012-2017. Based on the system engineering context consisting of "Human, Machine and Environment", human factors at sea, i.e., those factors relevant to the seafarers, are consistently underlined. STCW convention is the unique but systematic international maritime legislation looking after the "professional competency standards" of seafarers. The amendment thereto is of great significance for the Maritime Education and Training (MET) systems, which should be fully understood so as to respond to it effectively. The paper analyzes major impacts brought by the amendment, with purposes to raise recommendations for MET systems to implement the amendment effectively.
文摘It has been classed 856 species of the mollusks which belong to 120 families and five classes living in western coast of the Tonkin Gulf. The class Gastropod was the most abundant, with 449 species, the Bivalve with 368 species, the Scaphopoda with 10 species, the Cephalopods with 19 species and the Amphineura with eight species. Standing stock was estimated about 366,749 tons, that annually caught 80,000 tons. The causes of the resource depletion were human and natural, but the human factors played a key role. The fundamental orientations for developing the resources include: exploiting during harvest seasons, planning suitable aquaculture, moderate exploitation so the resources can restore themselves, combining exploitation and conservation.
文摘This paper is a summary of the studies done on the importance of the cognitive styles especially reflectivity/impulsivity on the process of language acquisition. It discusses the importance of this cognitive style as an important factor on the effectiveness of awareness raising activities. In the previous studies, the importance of awareness raising has been found as an effective and facilitating factor in the process of the L2 (second language) acquisition, but the effect of different individual factors on its being usefulness has not been focused on; therefore, this study is an attempt to review and explore the importance of one of the individual factors, i.e., being reflective/impulsive cognitive style on the effectiveness of awareness raising activities. It is gathered that learners with different cognitive styles (being reflective/impulsive) react differently to the awareness giving activities, and the study tries to emphasize the importance of this factor on the usefulness of awareness raising and emphasizes the fact that in the field of awareness giving this factor should be attached impotence and accounted for as an effective factor.
文摘The objectives of the research are to determine the important factors and the performance factors of the attributes in selecting venues (particularly convention hotels and convention centers) through investigating the meeting planners' set of needs and to identify factors and attributes relating to the venue marketing mix for MICE industry in Thailand. This paper has applied the hospitality and the tourism marketing mixes that are important to the MICE destination selection (particularly venues) for creating a new venue marketing mix. Therefore, the study is based on the importance levels of venue selection through each marketing mix factors including all attributes in the meeting planners' perspectives on behalf of their organizations, which will be able to reflect a set of their real needs that could bring about development of a venue marketing mix model that exclusively accommodates MICE organizers. The data was collected using self-administered questionnaires from 229 meeting planners. Statistically significant determinants of the meeting planners' overall importance levels indicated that in all of the 8 marketing mix factors (68 attributes), the people factor was perceived to be the most important factor. The package factor was perceived to have a moderate level of importance. The other factors perceived to be important included Product, Price, Place, Promotion, Physical evidence and Process. It is also found from the factor analysis that the new venue marketing mix contained 8 marketing mix factors with 61 attributes for venue business in Thailand. It is recommended from the research findings that venue management be more concerned with and focus on the attributes of the people factor.
文摘Internal auditors hold a unique position in their organizations to prevent, deter, and detect corporate wrongdoings. However, the role of this profession in investigating their ethical decision-making behaviors towards internal whistle-blowing intentions has been very often neglected. Furthermore, although extensive researches have been undertaken on the issue of whistle blowing globally, empirical studies on this area are still scarce in Malaysia. This paper examines internal whistle-blowing intentions among internal auditors in Malaysia by utilizing three independent vignettes. A mail survey was conducted to investigate demographic and individual factors that could influence internal auditors' ethical decision-making processes. The likelihood for internal whistle-blowing intentions was significant among internal auditors' ethical judgments for all the three vignettes. Demographic factors (gender, age, and tenure) and other individual factors (locus of control and organizational commitment) failed to explain the likelihood of internal auditors' internal whistle-blowing intentions. Findings should aid researchers in their understandings of the determinants of individuals' internal whistle-blowing behaviors.
基金Supported by The Federal Ministry of Research (BMBF-01 GN0984)
文摘AIM:To investigate effects of hepatotropic growth factors on radical production in rat hepatocytes during sepsis.METHODS:Rat hepatocytes,isolated by collagenase perfusion,were incubated with a lipopolysaccharide(LPS)-containing cytokine mixture of interleukin-1β,tumor necrosis factor-α and interferon-γ to simulate sepsis and either co-incubated or pre-incubated with hepatotropic growth factors,e.g.hepatocyte growth factor,epidermal growth factor and/or transforming growth factor-α.Cells were analyzed for glutathione levels.Culture supernatants were assayed for produc-tion of reactive oxygen intermediates(ROIs) as well as NO2-,NO3-and S-nitrosothiols.To determine cellular damage,release of aspartate aminotransferase(AST) into the culture medium was analyzed.Activation of nuclear factor(NF)-κB was measured by electrophoretic mobility shift assay.RESULTS:Rat hepatocytes treated with the LPS-containing cytokine mixture showed a significant increase in ROI and nitrogen oxide intermediate formation.AST leakage was not significantly increased in cells treated with the LPS-containing cytokine mixture,independent of growth-factor co-stimulation.However,pretreatment with growth factors significantly reduced AST leakage and ROI formation while increasing cellular glutathione.Application of growth factors did not result in increased NF-κB activation.Pretreatment with growth factors further increased formation of NO2-,NO3-and S-nitrosothiols in hepatocytes stimulated with LPS-containing cytokine mixture.Thus,we propose that,together with an increase in glutathione increased NO2-,NO3-formation might shift their metabolism towards non-toxic products.CONCLUSION:Our data suggest that hepatotropic growth factors positively influence sepsis-induced hepatocellular injury by reducing cytotoxic ROI formation via induction of the cellular protective antioxidative systems.
基金National Natural Science Foundation of China(41201110)Young Talents Foundation of Nanjing Institute of Geography and Limnology of CAS(NIGLAS2011QD03)
文摘The interactive effects of natural and human factors on ecosystems have been well studied, and the quantitative assessment of large-scale ecological vulnerability caused by natural and human factors is now one of the most active topics in the ifeld. Taking the Guangxi Xijiang River Economic Belt in southwest China (GXEB) as a case study, we assess ecological vulnerability based on the Vulnerability Scoping Diagram (VSD) model. The indices system is decomposed into three sub objects, ten elements and 25 indicators layer by layer, which included factors from both natural and human ifelds. Results indicate that zones with lower, middle-lower, middle, middle-higher and higher vulnerability account for 11.31%, 22.63%, 27.60%, 24.39%, and 14.07%, respectively. The western and eastern parts of GXEB are more vulnerable than the central part and the mountain and urban areas are of higher vulnerability than the basins and river valleys. Compared with a vulnerability assessment based on natural factors only, it is concluded that human activities indeed cause the transition from naturally stable zones to vulnerable zones. The nature-dominated vulnerable zones are different with human-dominated ones in size and distribution, the latter being smaller, more scattered and distributed in urban areas and their surroundings. About 53%of total construction land is distributed in zones with middle and middle-higher ecological vulnerability;less vulnerable zones should attract construction in the future. Relevant suggestions are proposed on how to reduce vulnerability according to inducing factors. The VSD model has a signiifcant advantage in the quantitative evaluation of ecological vulnerability, but is insufficient to distinguish nature- or human-dominated vulnerability quantitatively.
基金supported by the National Basic Research Program of China(Grant No.2015CB452702)the National Natural Science Foundation of China(Grant Nos.41671090&41601091)
文摘Terrain plays a key role in landscape pattern formation, particularly in the transition zones from mountains to plains.Exploring the relationships between terrain characteristics and landscape types in terrain-complex areas can help reveal the mechanisms underlying the relationships. In this study, Qihe River Basin, situated in the transition zone from the Taihang Mountains to the North-China Plain, was selected as a case study area. First, the spatial variations in the relief amplitudes(i.e.,high-amplitude terrain undulations) were analyzed. Second, the effects of relief amplitudes on the landscape patterns were indepth investigated from the perspectives of both landscape types and landscape indices. Finally, a logistic regression model was employed to examine the relationships between the landscape patterns and the influencing factors(natural and human) at different relief amplitudes. The results show that with increasing relief amplitude, anthropogenic landscapes gradually give in to natral landscapes. Specifically, human factors normally dominate the gentle areas(e.g., flat areas) in influencing the distribution of landscape types, and natural factors normally dominate the highly-undulating areas(e.g., moderate relief areas). As for the intermediately undulating areas(i.e.,medium relief amplitudes), a combined influence of natural and human factors result in the highest varieties of landscape types. The results also show that in micro-relief areas and small relief areas where natural factors and human factors are more or less equally active,landscape types are affected by a combination of natural and human factors.The combination leads to a high fragmentation and a high diversity of landscape patterns. It seems that appropriate human interferences in these areas can be conducive to enhancing landscape diversity and that inappropriate human interferences can aggravate the problems of landscape fragmentation.
基金supported by the Excellent Young Scientists Fund(Grant No.41622108)the National Basic Research Program of China(973Program)(Grant No.2015CB954103)the Priority Academic Program Development of Jiangsu Higher Education Institutions(Grant No.164320H116)
文摘Geography requires a comprehensive understanding of both natural and human factors,as well as their interactions.Due to the complexity and multiplicity of geographic problems,various theories and methods for geographic modelling and simulation have been proposed.Currently,geography has entered an era in which quantitative analysis and modelling are essential for understanding the mechanisms of geographic processes.As the basic idea of quantitative spatial analysis,the specified space often needs to be partitioned by a series of small computational units(cells),i.e.,grids.Thus,there is a close relationship between the grids and geographic modelling.This article reviews the mainstream and typical grids used for modelling and simulation.In addition to classification,the derived theories and technologies,including grid generation methods,data organization strategies,multi-dimensional querying methods,and grid adaptation techniques,are discussed.For integrated geographic simulation to explore comprehensive geographic problems,we argued that it is reasonable to build bridges among different types of grids(e.g.,transformation strategies),and more powerful grids that can support multi-type of numerical computation are urgently needed.