AIM: To identity the factors influencing colorectal cancer (CRC) screening behavior and willingness among Chinese outpatients.METHODS: An outpatient-based face-to-face survey was conducted from August 18 to Septem...AIM: To identity the factors influencing colorectal cancer (CRC) screening behavior and willingness among Chinese outpatients.METHODS: An outpatient-based face-to-face survey was conducted from August 18 to September 7, 2010 in Changhai Hospital. A total of 1200 consecutive patients aged ≥ 18 years were recruited for interview. The patient's knowledge about CRC and screening was pre-measured as a predictor variable, and other pre- dictors included age, gender, educational level, month- ly household income and health insurance status. The relationship between these predictors and screening behavior, screening willingness and screening approach were examined using Pearson's 2 test and logistic regression analyses.RESULTS: Of these outpatients, 22.5% had undergone CRC screening prior to this study. Patients who had participated in the screening were more likely to have good knowledge about CRC and screening (OR: 5.299, 95% CI: 3.415-8.223), have health insurance (OR: 1.996, 95% CI: 1.426-2.794) and older in age. Higher income, however, was found to be a barrier to the screening (OR: 0.633, 95% CI: 0.467-0.858). An analysis of screening willingness showed that 37.5% of the patients would voluntarily participated in a screen at the recommended age, but 41.3% would do so under doctor's advice. Screening willingness was positively correlated with the patient's knowledge sta- tus. Patients with higher knowledge levels would like to participate in the screening (OR: 4.352, 95% CI: 3.008-6.298), and they would select colonoscopy as a screening approach (OR: 3.513, 95% CI: 2.290-5.389). However, higher income level was, again, a bar- rier to colonoscopic screening (OR: 0.667, 95% CI: 0.505-0.908). CONCLUSION: Patient's level of knowledge and in-ome should be taken into consideration when conducting a feasible CRC screening.展开更多
The Ms 8.0 May 12,2008 Wenchuan earthquake triggered tens of thousands of landslides.The widespread landslides have caused serious casualties and property losses,and posed a great threat to post-earthquake reconstruct...The Ms 8.0 May 12,2008 Wenchuan earthquake triggered tens of thousands of landslides.The widespread landslides have caused serious casualties and property losses,and posed a great threat to post-earthquake reconstruction.A spatial database,inventoried 43,842 landslides with a total area of 632 km 2,was developed by interpretation of multi-resolution remote sensing images.The landslides can be classified into three categories:swallow,disrupted slides and falls;deep-seated slides and falls,and rock avalanches.The correlation between landslides distribution and the influencing parameters including distance from co-seismic fault,lithology,slope gradient,elevation,peak ground acceleration(PGA) and distance from drainage were analyzed.The distance from co-seismic fault was the most significant parameter followed by slope gradient and PGA was the least significant one.A logistic regression model combined with bivariate statistical analysis(BSA) was adopted for landslide susceptibility mapping.The study area was classified into five categories of landslide susceptibility:very low,low,medium,high and very high.92.0% of the study area belongs to low and very low categories with corresponding 9.0% of the total inventoried landslides.Medium susceptible zones make up 4.2% of the area with 17.7% of the total landslides.The rest of the area was classified into high and very high categories,which makes up 3.9% of the area with corresponding 73.3% of the total landslides.Although the susceptibility map can reveal the likelihood of future landslides and debris flows,and it is helpful for the rebuilding process and future zoning issues.展开更多
The implementation of pasture contracting policies in the Tibetan Plateau has been of widespread concern in the scientific community and related government departments. Studying the effects of the implementation of pa...The implementation of pasture contracting policies in the Tibetan Plateau has been of widespread concern in the scientific community and related government departments. Studying the effects of the implementation of pasture contracting policies will help us understand herders' attitudes toward those policies and to amend existing policies effectively.This paper analyzes 135 herder families' grazing management behavior using participatory rural appraisal(PRA), quantitative analysis and a Logistic regression model in three townships of Nagqu County in remote areas of the Tibetan Plateau, China. The results show that the herders have become settled and are no longer nomadic, so the settlement project has basically been completed and the policy of contracting for grazing rights is being gradually implemented in Nagqu County. Since the grazing rights and pastures were under contract, group-based management has been widely accepted in this area, which helps the herders deal with constraints, such as limited pasture area, a small grazing radius, controlled family animal husbandry and an uneven distribution of water. The herders that have more family members available for labor, higher proportion of family members with good health, and higher income from animal husbandry tend to choose household-based management.Herders tend to choose group-based management when higher quality winter pastures are available.展开更多
Community plays an important role in the preservation of agricultural heritage system (AHS). Recently, many AHS have been valorized as interesting resources for rural tourism. The expectations are that tourism devel...Community plays an important role in the preservation of agricultural heritage system (AHS). Recently, many AHS have been valorized as interesting resources for rural tourism. The expectations are that tourism development (TD) can be supportive for the conservation of AHS while creating benefits for local communities. In this study, two mountainous pilot villages (Longxian and Xiaohuang) in a global conservation project for traditional agricutural systems - Globally Important Agricultural Heritage Systems (GIAHS) were selected to identify the relationship between AHS conservation and TD. The study undertook in-depth interviews, and questionnaires of village residents and informal discussions with local villagers. A t-test and a linear regression model were implemented to explore the comparative dimensions of the two communities with different geographical location, economic situation, and stage of TD. The research found some similarities and differences in the two mountainous communities during AHS conservation and TD. Firstly, AHS are preservaed well in both villages unconsiously, while the residents in Xiaohuang value more highly the heritage elements than the respondents in Longxian, and the villagers in Xiaohuang are more worried about their heritage system; Secondly, both villages expect lots of benefits from TD and they clearly perceive more positive than negative impact from tourism and thus approve TD, while the hugedifferent perception on transportation and accessibility in the two villages reflects the bottleneck of TD in Xiaohuang village. At the same time, the respondents from Xiaohuang perceive more positive and fewer negative impact from tourism than the respondents from Longxian. Thirdly, the respondents in the two villages all show positive attitudes towards participation in tourism mostly motivated by the high income expectation. The main factors to determine the community perception in two villages were also analyzed based on the data process. A location-based coneeputal framework of AHS conservation in partnership with TD at community scale is proposed at the end of the paper. The dynamics of tourism development, that could enhance a better understanding of the complex relationship between conservation objectives and tourism development are discussed.展开更多
The structure and function of network is a central issue in landscape ecology.Road networks with hierarchical structure are crucial for understanding landscape dynamics.In this study,we compared the distribution of na...The structure and function of network is a central issue in landscape ecology.Road networks with hierarchical structure are crucial for understanding landscape dynamics.In this study,we compared the distribution of national road,provincial road,county road and rural road in the Three Parallel Rivers Region(TPRR)in Yunnan Province of China,and estimated the effect of roads(and other factors)on the spatial patterns of land use and land cover with logistic regression.In addition,we analyzed the land use and land cover change(LUCC)and landscape fragmentation in 1989–2005 along a buffer zone of the primary traffic corridor,national road G214.The results showed that,county and rural roads had much higher percentage of length extending into more natural habitats at higher elevation and steeper slope,compared with the higher level roads in this region.While the distributions of natural land cover types were dominated by environmental factors,human land use types i.e.,building land and farmland types were significantly related with roads,linking more closely with lower level roads.The LUCC dynamics(1989–2005)of the G214 buffer zone showed a general trend of land transformation from conifer forests and valley arid shrubs to building land and farmland,and from ice and snow to alpine shrubs and forests.With the length of G214 unchanged during the time,the overall landscape pattern changed little in the buffer zone,but habitat fragmentation and area decrease had occurred for the natural vegetation types,in contrast to patch mergence and expansion of human land use types,and landscape fragmentation was intensified above 2500 m a.s.l.but declined below the elevation.The results indicated the dynamics of landscape composition and patch type level distribution in spite of the stability of the overall landscape pattern,and implied the potential role of roads,especially the low level roads on landscape changes.展开更多
Based on the 1990, 2000 and 2011 Landsat TM/ETM+ remote sensing data, glacier information of three periods in the Chinese Tianshan Mountains were extracted by using ratio threshold method(TM3/TM5) and visual interpret...Based on the 1990, 2000 and 2011 Landsat TM/ETM+ remote sensing data, glacier information of three periods in the Chinese Tianshan Mountains were extracted by using ratio threshold method(TM3/TM5) and visual interpretation, combined with digital processing of satellite images and analysis in GIS. The climate data in the surrounding area were analyzed by using linear regression, Mann-Kendall abrupt test, and Morlet wavelet analysis. Study results showed that: over the 23 years investigation, the glacier areas have markedly decreased. In the last 12 years(2000 to 2011), the rate of retreat has begun to accelerate. The most dramatic glacier shrinkage occurred in the central region, the lowest in the eastern region. The mean summer temperature and warm precipitation in Chinese Tianshan Mountains had an increasing trend, with rates of 0.22°C /10 a and 5.1mm/10 a from 1960 to 2011, respectively. Mean summer temperature have experienced a strong increase in 1998. The analysis of the results showed that the rise of mean summer temperature was the main factor that contributed to glacier shrinkage. Regional differences of glacier area changes were investigated by analyzing glacier behavior in five study sub-regions; regional differences are related to local climate, to the relative proportion of glaciers in different size classes, altitudinal and aspect distribution of glaciated areas. In addition, the lag theory indicated that glaciers may accelerate the retreat in the next decade, considering climate trends recognized for the period 2000-2011.展开更多
Grassland fire is one of the most important disturbance factors in the natural ecosystems.This paper focuses on the spatial distribution of long-term grassland fire patterns in the Hulun Buir Grassland located in the ...Grassland fire is one of the most important disturbance factors in the natural ecosystems.This paper focuses on the spatial distribution of long-term grassland fire patterns in the Hulun Buir Grassland located in the northeast of Inner Mongolia Autonomous Region in China.The density or ratio of ignition can reflect the relationship between grassland fire and different ignition factors.Based on the relationship between the density or ratio of ignition in different range of each ignition factor and grassland fire events,an ignition probability model was developed by using binary logistic regression function and its overall accuracy averaged up to 81.7%.Meanwhile it was found that daily relative humidity,daily temperature,elevation,vegetation type,distance to county-level road,distance to town are more important determinants of spatial distribution of fire ignitions.Using Monte Carlo method,we developed a time-dependent stochastic ignition probability model based on the distribution of inter-annual daily relative humidity and daily temperature.Through this model,it is possible to estimate the spatial patterns of ignition probability for grassland fire,which will be helpful to the quantitative evaluation of grassland fire risk and its management in the future.展开更多
Objective: To investigate the uptake rate of prostate specific antigen(PSA) testing among Hong Kong Chinese males aged 50 or above, and identify factors associated with the likelihood of undergoing a PSA test.Methods:...Objective: To investigate the uptake rate of prostate specific antigen(PSA) testing among Hong Kong Chinese males aged 50 or above, and identify factors associated with the likelihood of undergoing a PSA test.Methods: A population-based telephone survey was conducted in Hong Kong in 2007. The survey covered demographic information, perceived health status, use of complementary therapy, cancer screening behavior, perceived susceptibility to cancer and family history of cancer. Descriptive statistics, percentages and logistic regression analysis were used for data analysis.Results: A total of 1,002 men aged 50 or above took part in the study(response rate =67%), and the uptake rate of PSA testing was found to be 10%. Employment status, use of complementary therapy, perceiving regular visits to a doctor as good for health and the recommendations of health professionals were significant factors associated with PSA testing.Conclusion: The uptake rate of PSA testing in the study population was very low. Among all the factors identified, recommendations from health professionals had the strongest association with the uptake of PSA testing, and they should therefore take an active role in educating this population about cancer prevention and detection.展开更多
Snow depth is a general input variable in many models of agriculture,hydrology,climate and ecology.This study makes use of observational data of snow depth and explanatory variables to compare the accuracy and effect ...Snow depth is a general input variable in many models of agriculture,hydrology,climate and ecology.This study makes use of observational data of snow depth and explanatory variables to compare the accuracy and effect of geographically weighted regression kriging(GWRK)and regression kriging(RK)in a spatial interpolation of regional snow depth.The auxiliary variables are analyzed using correlation coefficients and the variance inflation factor(VIF).Three variables,Height,topographic ruggedness index(TRI),and land surface temperature(LST),are used as explanatory variables to establish a regression model for snow depth.The estimated spatial distribution of snow depth in the Bayanbulak Basin of the Tianshan Mountains in China with a spatial resolution of 1 km is obtained.The results indicate that 1)the result of GWRK's accuracy is slightly higher than that of RK(R^2=0.55 vs.R^2=0.50,RMSE(root mean square error)=0.102 m vs.RMSE=0.077 m);2)for the subareas,GWRK and RK exhibit similar estimation results of snow depth.Areas in the Bayanbulak Basin with a snow depth greater than 0.15m are mainly distributed in an elevation range of 2632.00–3269.00 m and the snow in this area comprises 45.00–46.00% of the total amount of snow in this basin.However,the GWRK resulted in more detailed information on snow depth distribution than the RK.The final conclusion is that GWRK is better suited for estimating regional snow depth distribution.展开更多
In order to better understand the prevailing mechanism of CO2 storage in coal and estimate CO2 sequestration capacity of a coal seam and enhanced coalbed methane recovery (ECBM) with CO2 injection into coal, we inve...In order to better understand the prevailing mechanism of CO2 storage in coal and estimate CO2 sequestration capacity of a coal seam and enhanced coalbed methane recovery (ECBM) with CO2 injection into coal, we investigated the preferential adsorption of CH4 and CO2 on coals. Adsorption of pure CO2, CH4 and their binary mixtures on high-rank coals from Qinshui Basin in China were employed to study the preferential adsorption behaviour. Multiple regression equations were presented to predict CH4 equi- librium concentration from equilibrium pressure and its initial-composition in feed gas. The results show that preferential adsorption of CO2 on coals over the entire pressure range under competitive sorption conditions was observed, however, preferential adsorption of CH4 over CO2 on low-volatile bituminous coal from higher CH4-compostion in source gas was found at up to 1O MPa pressure. Preferential adsorp- tion of CO2 increases with increase of CH4 concentration in source gas, and decreases with increasing pressure. Although there was no systematic investigation of the effect of coal rank on preferential adsorp- tion, there are obvious differences in preferential adsorption of gas between low-volatile bituminous coal and anthracite. The obtained preferential adsorption gives rise to the assumption that CO2 sequestration in coal beds with subsequent CO2-ECBM might be an ootion in Qinshui Basins, China.展开更多
A statistical regression downscaling method was used to project future changes in precipitation over eastern China based on Phase 5 of the Coupled Model Intercomparison Project (CMIPS) the Representative Concentrati...A statistical regression downscaling method was used to project future changes in precipitation over eastern China based on Phase 5 of the Coupled Model Intercomparison Project (CMIPS) the Representative Concentration Pathway (RCP) scenarios simulated by the second spectral version of the Flexible Global Ocean- Atmosphere-Land System (FGOALS-s2) model. Our val- idation results show that the downscaled time series agree well with the present observed precipitation in terms of both the annual mean and the seasonal cycle. The regres- sion models built from the historical data are then used to generate future projections. The results show that the en- hanced land-sea thermal contrast strengthens both the subtropical anticyclone over the western Pacific and the east Asian summer monsoon flow under both RCPs. However, the trend of precipitation in response to warming over the 21 st century are different across eastern Chi- na under different RCPs. The area to the north of 32°N is likely to experience an increase in annual mean precipitation, while for the area between 23°N and 32°N mean precipitation is projected to decrease slightly over this century under RCP8.5. The change difference between scenarios mainly exists in the middle and late century. The land-sea thermal contrast and the associated east Asian summer monsoon flow are stronger, such that precipitation increases more, at higher latitudes under RCP8.5 compared to under RCP4.5. For the region south of 32°N, rainfall is projected to increase slightly under RCP4.5 but decrease under RCP8.5 in the late century. At the high resolution of 5 km, our statistically downscaled results for projected precipitation can be used to force hydrological models to project hydrological processes, which will be of great benefit to regional water planning and management.展开更多
Low Carbon Employment is an inevitable choice for the purpose of "energy-saving and emission reduction" and "promoting employment". By Multi-variable Linear Backward Regression method, this study presents an empir...Low Carbon Employment is an inevitable choice for the purpose of "energy-saving and emission reduction" and "promoting employment". By Multi-variable Linear Backward Regression method, this study presents an empirical analysis of the emplovment impact of policy variables indexes that involves economic pull, industry upgrading, population development, technical inputs and so on. The paper demonstrates that wide range offactors will affect low carbon employment, that industry upgrading will affect how carbon employment remarkably, that to increase years of people education will notably improve low carbon employment level of secondary vocational-technical labor, and that to raise technical inputs will significantly enhance college students' low carbon employment.展开更多
High PM_(2.5) concentrations and frequent air pollution episodes during late autumn and winter in Jilin Province have attracted attention in recent years. To describe the spatial and temporal variations of PM_(2.5) co...High PM_(2.5) concentrations and frequent air pollution episodes during late autumn and winter in Jilin Province have attracted attention in recent years. To describe the spatial and temporal variations of PM_(2.5) concentrations and identify the decisive influencing factors, a large amount of continuous daily PM_(2.5) concentration data collected from 33 monitoring stations over 2-year period from 2015 to 2016 were analyzed. Meanwhile, the relationships were investigated between PM_(2.5) concentrations and the land cover, socioeconomic and meteorological factors from the macroscopic perspective using multiple linear regressions(MLR) approach. PM_(2.5) concentrations across Jilin Province averaged 49 μg/m^3, nearly 1.5 times of the Chinese annual average standard, and exhibited seasonal patterns with generally higher levels during late autumn and over the long winter than the other seasons. Jilin Province could be divided into three kinds of sub-regions according to 2-year average PM_(2.5) concentration of each city. Most of the spatial variation in PM_(2.5) levels could be explained by forest land area, cultivated land area, urban greening rate, coal consumption and soot emissions of cement manufacturing. In addition, daily PM_(2.5) concentrations had negative correlation with daily precipitation and positive correlation with air pressure for each city, and the spread and dilution effect of wind speed on PM_(2.5) was more obvious at mountainous area in Jilin Province. These results indicated that coal consumption, cement manufacturing and straw burning were the most important emission sources for the high PM_(2.5) levels, while afforestation and urban greening could mitigate particulate air pollution. Meanwhile, the individual meteorological factors such as precipitation, air pressure, wind speed and temperature could influence local PM_(2.5) concentration indirectly.展开更多
AIM:To assess the risk of biliary and pancreatic cancers in a large cohort of patients with type 2 diabetes mellitus(DM) .METHODS:Eligibility for this study included patients with type 2 DM(ICD-9 code 250.0) who were ...AIM:To assess the risk of biliary and pancreatic cancers in a large cohort of patients with type 2 diabetes mellitus(DM) .METHODS:Eligibility for this study included patients with type 2 DM(ICD-9 code 250.0) who were discharged from Department of Veteran Affairs hospitals between 1990 and 2000.Non-matched control patients without DM were selected from the same patient treatment files during the same period.Demographic information included age,sex and race.Secondary diagnoses included known risk factors based on their ICD-9 codes.By multivariate logistic regression,the occurrence of biliary and pancreatic cancer was compared between case subjects with DM and controls without DM.RESULTS:A total of 1172496 case and control subjects were analyzed.The mean age for study and control subjects was 65.8 ± 11.3 and 64.8 ± 12.6 years,respectively.The frequency of pancreatic cancer in subjects with DM was increased(0.9%) in comparison to control subjects(0.3%) with an OR of 3.22(95% CI:3.03-3.42) .The incidence of gallbladder andextrahepatic biliary cancers was increased by twofold in diabetic patients when compared to controls.The OR and 95% CI were 2.20(1.56-3.00) and 2.10(1.61-2.53) ,respectively.CONCLUSION:Our study demonstrated that patients with DM have a threefold increased risk for developing pancreatic cancer and a twofold risk for developing biliary cancer.展开更多
AIM: To explore the association between single nucleotide polymorphisms (SNPs) at 8q24 and gastric cancer risk. METHODS: A case-control investigation including 212 gastric cancer patients and 377 healthy controls was ...AIM: To explore the association between single nucleotide polymorphisms (SNPs) at 8q24 and gastric cancer risk. METHODS: A case-control investigation including 212 gastric cancer patients and 377 healthy controls was conducted. The genotypes of SNPs (rs6983267, rs7008482 and rs10808555) were examined and established through polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Multivariate logistic regression models were used to evaluate the association between SNPs and gastric cancer. RESULTS: The genotype frequencies of rs6983267 in gastric cancer patients were obviously different from those in the control (P = 0.005). GT genotype of rs6983267 was associated with an increased risk of gastric cancer compared with GG genotype (adjusted odds ratio = 2.01, 95% confidence interval: 1.28-3.14). Further stratified analysis indicated that rs6983267 GT genotype facilitated the risk of gastric cancer of non-cardiac and intestinal type (OR: 2.638, 95% CI: 1.464-4.753; OR: 1.916, 95% CI: 1.166-3.150, respectively). CONCLUSION: This study demonstrates for the first time that rs6983267 is involved in susceptibility to gastric cancer, although further large-sample investigations are still needed.展开更多
Objective:The purpose of the study was to compare the preventive care use and health between the elderly living alone and living with other individuals and identify strategies to improve the preventive care use among ...Objective:The purpose of the study was to compare the preventive care use and health between the elderly living alone and living with other individuals and identify strategies to improve the preventive care use among the elderly living alone.Methods:A questionnaire including socioeconomic characteristics,preventive care use,health status and Social Support Rate Scale was administered to 240 elderly living alone and 244 elderly living with other individuals in Shanghai,China.Logistic regression analysis was used to examine the predictors of preventive care use.Results:The elderly living alone were more likely to be single(never married,divorced,separated and widowed),have lower social support and income,utilize less routine physical check-up and blood glucose screenings,have worse self-reported health and have limitations in IADL compared to the elderly living with other individuals.Women,old age,high education,income and social support and close to medical institutions were positively associated with routine physical check-up among the elderly.Conclusion:Living alone was associated with less preventive care use and worse health.It was important to provide more social support and economic support for the elderly living alone to increase their preventive health care service utilization and improve their health status.展开更多
BackgroundPocket hematoma is one of the major complications associated with cardiovascular implantable electronic devices (CIEDs) implantation. The aim of this study is to evaluate the impact of body mass index (BM...BackgroundPocket hematoma is one of the major complications associated with cardiovascular implantable electronic devices (CIEDs) implantation. The aim of this study is to evaluate the impact of body mass index (BMI) on the occurrence of pocket hematoma after CIEDs implantation.MethodsThe study is a retrospective review of 972 patients receiving CIEDs implantation between 2008 and 2012 in a tertiary hospital.ResultsTwenty two patients (2.2%) developed severe pocket hematoma requiring re-intervention. The hematoma rate (4.6%,n = 15) of patients with a BMI of 〈 23 kg/m2 was significantly higher compared with that of patients with a BMI of≥23 kg/m2 (1.1%, n = 7,P〈 0.001). In multivariate regression analysis, a BMI 〈 23.0 kg/m2 may be associated with the development of severe pocket hema-toma. An increase of 1.0 kg/m2 in BMI was associated with lower incidence of hematoma formation (OR: 0.84; 95% CI: 0.74-0.95;P = 0.006).ConclusionBMI 〈 23 kg/m2 was associated with a higher incidence of pocket hematoma, requiring re-intervention. The data sup-port that great care must be taken when patients were with a lower BMI received CIEDs implantation.展开更多
The author carefully selected earthquakes with M_L=4.0~5.0, 215 occurring in the crust in the Taiwan region. The attenuation characteristics of maximum displacement recorded by the Fujian digital network have been ob...The author carefully selected earthquakes with M_L=4.0~5.0, 215 occurring in the crust in the Taiwan region. The attenuation characteristics of maximum displacement recorded by the Fujian digital network have been obtained by multi-analysis as follows:logA=2.07+231.1/Δ (150km≤Δ≤650km) And the corresponding expression of calibration function is, R(Δ)=3.45-231.1(1/Δ-0.01) (150km≤Δ≤650km) Then, the author determined the magnitude and its error with the data from the Fujian network using the calibration function brought forward in 1997 and the above formula for 790 earthquakes occurring in the crust in the Taiwan region from September 1997 ~ August 2005. The result indicates that the average error of the network is 0.20 with the former and 0.18 with the latter. The average error is 0.13 with the latter with station correction. Compared with the magnitude determined by Taiwan seismologists, the magnitude value with the former is lower by 0.50 on average and that with the latter is higher by 0.08 on average.展开更多
Regional Landslide Susceptibility Zonation(LSZ) is always challenged by the available amount of field data, especially in southwestern China where large mountainous areas and limited field information coincide. Statis...Regional Landslide Susceptibility Zonation(LSZ) is always challenged by the available amount of field data, especially in southwestern China where large mountainous areas and limited field information coincide. Statistical learning algorithms are believed to be superior to traditional statistical algorithms for their data adaptability. The aim of the paper is to evaluate how statistical learning algorithms perform on regional LSZ with limited field data. The focus is on three statistical learning algorithms, Logistic Regression(LR), Artificial Neural Networks(ANN) and Support Vector Machine(SVM). Hanzhong city, a landslide prone area in southwestern China is taken as a study case. Nine environmental factors are selected as inputs. The accuracies of the resulting LSZ maps are evaluated through landslide density analysis(LDA), receiver operating characteristic(ROC) curves and Kappa index statistics. The dependence of the algorithm on the size of field samples is examined by varying the sizes of the training set. The SVM has proven to be the most accurate and the most stable algorithm at small training set sizes and on all known landslide sizes. The accuracy of SVM shows a steadilyincreasing trend and reaches a high level at a small size of the training set, while accuracies of LR and ANN algorithms show distinct fluctuations. The geomorphological interpretations confirm the strength of SVM on all landslide sizes. Our results show that the strengths of SVM in generalization capability and model robustness make it an appropriate and efficient tool for regional LSZ with limited landslide field samples.展开更多
文摘AIM: To identity the factors influencing colorectal cancer (CRC) screening behavior and willingness among Chinese outpatients.METHODS: An outpatient-based face-to-face survey was conducted from August 18 to September 7, 2010 in Changhai Hospital. A total of 1200 consecutive patients aged ≥ 18 years were recruited for interview. The patient's knowledge about CRC and screening was pre-measured as a predictor variable, and other pre- dictors included age, gender, educational level, month- ly household income and health insurance status. The relationship between these predictors and screening behavior, screening willingness and screening approach were examined using Pearson's 2 test and logistic regression analyses.RESULTS: Of these outpatients, 22.5% had undergone CRC screening prior to this study. Patients who had participated in the screening were more likely to have good knowledge about CRC and screening (OR: 5.299, 95% CI: 3.415-8.223), have health insurance (OR: 1.996, 95% CI: 1.426-2.794) and older in age. Higher income, however, was found to be a barrier to the screening (OR: 0.633, 95% CI: 0.467-0.858). An analysis of screening willingness showed that 37.5% of the patients would voluntarily participated in a screen at the recommended age, but 41.3% would do so under doctor's advice. Screening willingness was positively correlated with the patient's knowledge sta- tus. Patients with higher knowledge levels would like to participate in the screening (OR: 4.352, 95% CI: 3.008-6.298), and they would select colonoscopy as a screening approach (OR: 3.513, 95% CI: 2.290-5.389). However, higher income level was, again, a bar- rier to colonoscopic screening (OR: 0.667, 95% CI: 0.505-0.908). CONCLUSION: Patient's level of knowledge and in-ome should be taken into consideration when conducting a feasible CRC screening.
基金supported by the National Key Technology R&D Program(Grant No. 2011BAK12B01)the Young Foundation of National Natural Science of China(Grant No.41202210)+1 种基金the Education Department Innovation Research Team Program(Grant No.IRT0812)the Young Foundation of Chengdu University of Technology and the Education Department of Sichuan Province (Grant Nos.2010QJ15 and 11ZB262)
文摘The Ms 8.0 May 12,2008 Wenchuan earthquake triggered tens of thousands of landslides.The widespread landslides have caused serious casualties and property losses,and posed a great threat to post-earthquake reconstruction.A spatial database,inventoried 43,842 landslides with a total area of 632 km 2,was developed by interpretation of multi-resolution remote sensing images.The landslides can be classified into three categories:swallow,disrupted slides and falls;deep-seated slides and falls,and rock avalanches.The correlation between landslides distribution and the influencing parameters including distance from co-seismic fault,lithology,slope gradient,elevation,peak ground acceleration(PGA) and distance from drainage were analyzed.The distance from co-seismic fault was the most significant parameter followed by slope gradient and PGA was the least significant one.A logistic regression model combined with bivariate statistical analysis(BSA) was adopted for landslide susceptibility mapping.The study area was classified into five categories of landslide susceptibility:very low,low,medium,high and very high.92.0% of the study area belongs to low and very low categories with corresponding 9.0% of the total inventoried landslides.Medium susceptible zones make up 4.2% of the area with 17.7% of the total landslides.The rest of the area was classified into high and very high categories,which makes up 3.9% of the area with corresponding 73.3% of the total landslides.Although the susceptibility map can reveal the likelihood of future landslides and debris flows,and it is helpful for the rebuilding process and future zoning issues.
基金supported by the National Natural Science Foundation of China (No. 41071066)the National Basic Research Program of China (No. 2010CB951704)the Dissertation Fellowship of the Peking University-Lincoln Institute Center for Urban Development and Land Policy
文摘The implementation of pasture contracting policies in the Tibetan Plateau has been of widespread concern in the scientific community and related government departments. Studying the effects of the implementation of pasture contracting policies will help us understand herders' attitudes toward those policies and to amend existing policies effectively.This paper analyzes 135 herder families' grazing management behavior using participatory rural appraisal(PRA), quantitative analysis and a Logistic regression model in three townships of Nagqu County in remote areas of the Tibetan Plateau, China. The results show that the herders have become settled and are no longer nomadic, so the settlement project has basically been completed and the policy of contracting for grazing rights is being gradually implemented in Nagqu County. Since the grazing rights and pastures were under contract, group-based management has been widely accepted in this area, which helps the herders deal with constraints, such as limited pasture area, a small grazing radius, controlled family animal husbandry and an uneven distribution of water. The herders that have more family members available for labor, higher proportion of family members with good health, and higher income from animal husbandry tend to choose household-based management.Herders tend to choose group-based management when higher quality winter pastures are available.
基金supported by the China National Natural Science Foundation (Grant Nos. 41201580, 40121553, 41201586)the research project on heritage tourism from China National Tourism Administration to Dr. Sun Ye-hong (Grant No. 13TAAG014)+2 种基金project of Construction of Innovative Teams and Teacher Career Development for Universities and Colleges under Beijing Municipality (Grant No. IDHT20130513)the international project of "GEF-FAO/GIAHS dynamic conservation and adaptive management", a research program at the Institute of Geographic SciencesNatural Resources Research of the Chinese Academy of Sciences
文摘Community plays an important role in the preservation of agricultural heritage system (AHS). Recently, many AHS have been valorized as interesting resources for rural tourism. The expectations are that tourism development (TD) can be supportive for the conservation of AHS while creating benefits for local communities. In this study, two mountainous pilot villages (Longxian and Xiaohuang) in a global conservation project for traditional agricutural systems - Globally Important Agricultural Heritage Systems (GIAHS) were selected to identify the relationship between AHS conservation and TD. The study undertook in-depth interviews, and questionnaires of village residents and informal discussions with local villagers. A t-test and a linear regression model were implemented to explore the comparative dimensions of the two communities with different geographical location, economic situation, and stage of TD. The research found some similarities and differences in the two mountainous communities during AHS conservation and TD. Firstly, AHS are preservaed well in both villages unconsiously, while the residents in Xiaohuang value more highly the heritage elements than the respondents in Longxian, and the villagers in Xiaohuang are more worried about their heritage system; Secondly, both villages expect lots of benefits from TD and they clearly perceive more positive than negative impact from tourism and thus approve TD, while the hugedifferent perception on transportation and accessibility in the two villages reflects the bottleneck of TD in Xiaohuang village. At the same time, the respondents from Xiaohuang perceive more positive and fewer negative impact from tourism than the respondents from Longxian. Thirdly, the respondents in the two villages all show positive attitudes towards participation in tourism mostly motivated by the high income expectation. The main factors to determine the community perception in two villages were also analyzed based on the data process. A location-based coneeputal framework of AHS conservation in partnership with TD at community scale is proposed at the end of the paper. The dynamics of tourism development, that could enhance a better understanding of the complex relationship between conservation objectives and tourism development are discussed.
基金Under the auspices of National Natural Science Foundation of China(No.41371190,31021001)Scientific and Tech-nical Projects of Western China Transportation Construction,Ministry of Transport of China(No.2008-318-799-17)
文摘The structure and function of network is a central issue in landscape ecology.Road networks with hierarchical structure are crucial for understanding landscape dynamics.In this study,we compared the distribution of national road,provincial road,county road and rural road in the Three Parallel Rivers Region(TPRR)in Yunnan Province of China,and estimated the effect of roads(and other factors)on the spatial patterns of land use and land cover with logistic regression.In addition,we analyzed the land use and land cover change(LUCC)and landscape fragmentation in 1989–2005 along a buffer zone of the primary traffic corridor,national road G214.The results showed that,county and rural roads had much higher percentage of length extending into more natural habitats at higher elevation and steeper slope,compared with the higher level roads in this region.While the distributions of natural land cover types were dominated by environmental factors,human land use types i.e.,building land and farmland types were significantly related with roads,linking more closely with lower level roads.The LUCC dynamics(1989–2005)of the G214 buffer zone showed a general trend of land transformation from conifer forests and valley arid shrubs to building land and farmland,and from ice and snow to alpine shrubs and forests.With the length of G214 unchanged during the time,the overall landscape pattern changed little in the buffer zone,but habitat fragmentation and area decrease had occurred for the natural vegetation types,in contrast to patch mergence and expansion of human land use types,and landscape fragmentation was intensified above 2500 m a.s.l.but declined below the elevation.The results indicated the dynamics of landscape composition and patch type level distribution in spite of the stability of the overall landscape pattern,and implied the potential role of roads,especially the low level roads on landscape changes.
基金supported by the National Science Foundation of China (Grant No. 41271024)the Fund Project for National Basic Science Talents Cultivation (Grant No. J1210065)the Fundamental Research Funds for the Central Universities- Excellent Graduate Innovation Project (Grant No. Lzujbky-2014-274)
文摘Based on the 1990, 2000 and 2011 Landsat TM/ETM+ remote sensing data, glacier information of three periods in the Chinese Tianshan Mountains were extracted by using ratio threshold method(TM3/TM5) and visual interpretation, combined with digital processing of satellite images and analysis in GIS. The climate data in the surrounding area were analyzed by using linear regression, Mann-Kendall abrupt test, and Morlet wavelet analysis. Study results showed that: over the 23 years investigation, the glacier areas have markedly decreased. In the last 12 years(2000 to 2011), the rate of retreat has begun to accelerate. The most dramatic glacier shrinkage occurred in the central region, the lowest in the eastern region. The mean summer temperature and warm precipitation in Chinese Tianshan Mountains had an increasing trend, with rates of 0.22°C /10 a and 5.1mm/10 a from 1960 to 2011, respectively. Mean summer temperature have experienced a strong increase in 1998. The analysis of the results showed that the rise of mean summer temperature was the main factor that contributed to glacier shrinkage. Regional differences of glacier area changes were investigated by analyzing glacier behavior in five study sub-regions; regional differences are related to local climate, to the relative proportion of glaciers in different size classes, altitudinal and aspect distribution of glaciated areas. In addition, the lag theory indicated that glaciers may accelerate the retreat in the next decade, considering climate trends recognized for the period 2000-2011.
基金Under the auspices of National Science & Technology Support Program of China(No.2006BAD20B00)
文摘Grassland fire is one of the most important disturbance factors in the natural ecosystems.This paper focuses on the spatial distribution of long-term grassland fire patterns in the Hulun Buir Grassland located in the northeast of Inner Mongolia Autonomous Region in China.The density or ratio of ignition can reflect the relationship between grassland fire and different ignition factors.Based on the relationship between the density or ratio of ignition in different range of each ignition factor and grassland fire events,an ignition probability model was developed by using binary logistic regression function and its overall accuracy averaged up to 81.7%.Meanwhile it was found that daily relative humidity,daily temperature,elevation,vegetation type,distance to county-level road,distance to town are more important determinants of spatial distribution of fire ignitions.Using Monte Carlo method,we developed a time-dependent stochastic ignition probability model based on the distribution of inter-annual daily relative humidity and daily temperature.Through this model,it is possible to estimate the spatial patterns of ignition probability for grassland fire,which will be helpful to the quantitative evaluation of grassland fire risk and its management in the future.
基金supported by the Chinese University of Hong Kong
文摘Objective: To investigate the uptake rate of prostate specific antigen(PSA) testing among Hong Kong Chinese males aged 50 or above, and identify factors associated with the likelihood of undergoing a PSA test.Methods: A population-based telephone survey was conducted in Hong Kong in 2007. The survey covered demographic information, perceived health status, use of complementary therapy, cancer screening behavior, perceived susceptibility to cancer and family history of cancer. Descriptive statistics, percentages and logistic regression analysis were used for data analysis.Results: A total of 1,002 men aged 50 or above took part in the study(response rate =67%), and the uptake rate of PSA testing was found to be 10%. Employment status, use of complementary therapy, perceiving regular visits to a doctor as good for health and the recommendations of health professionals were significant factors associated with PSA testing.Conclusion: The uptake rate of PSA testing in the study population was very low. Among all the factors identified, recommendations from health professionals had the strongest association with the uptake of PSA testing, and they should therefore take an active role in educating this population about cancer prevention and detection.
基金supported by Projects of International Cooperation and Exchanges NSFC (grant: 41361140361)the Special fund project of Chinese Academy of Sciences (grant: Y371164001)the key deployment project of Chinese Academy of Sciences (Grant No. KZZD-EW-12-2, KZZD-EW12-3)
文摘Snow depth is a general input variable in many models of agriculture,hydrology,climate and ecology.This study makes use of observational data of snow depth and explanatory variables to compare the accuracy and effect of geographically weighted regression kriging(GWRK)and regression kriging(RK)in a spatial interpolation of regional snow depth.The auxiliary variables are analyzed using correlation coefficients and the variance inflation factor(VIF).Three variables,Height,topographic ruggedness index(TRI),and land surface temperature(LST),are used as explanatory variables to establish a regression model for snow depth.The estimated spatial distribution of snow depth in the Bayanbulak Basin of the Tianshan Mountains in China with a spatial resolution of 1 km is obtained.The results indicate that 1)the result of GWRK's accuracy is slightly higher than that of RK(R^2=0.55 vs.R^2=0.50,RMSE(root mean square error)=0.102 m vs.RMSE=0.077 m);2)for the subareas,GWRK and RK exhibit similar estimation results of snow depth.Areas in the Bayanbulak Basin with a snow depth greater than 0.15m are mainly distributed in an elevation range of 2632.00–3269.00 m and the snow in this area comprises 45.00–46.00% of the total amount of snow in this basin.However,the GWRK resulted in more detailed information on snow depth distribution than the RK.The final conclusion is that GWRK is better suited for estimating regional snow depth distribution.
基金supported by the National Natural Science Foundation of China(Nos.51174127 and 21176145)the Natural Science Foundation of Shandong Province(No.ZR2011DM005)the Open Research Fund Program of Key Laboratory of Mine Disaster Prevention and Control(Shandong University of Science and Technology)(No.MDPC0806)
文摘In order to better understand the prevailing mechanism of CO2 storage in coal and estimate CO2 sequestration capacity of a coal seam and enhanced coalbed methane recovery (ECBM) with CO2 injection into coal, we investigated the preferential adsorption of CH4 and CO2 on coals. Adsorption of pure CO2, CH4 and their binary mixtures on high-rank coals from Qinshui Basin in China were employed to study the preferential adsorption behaviour. Multiple regression equations were presented to predict CH4 equi- librium concentration from equilibrium pressure and its initial-composition in feed gas. The results show that preferential adsorption of CO2 on coals over the entire pressure range under competitive sorption conditions was observed, however, preferential adsorption of CH4 over CO2 on low-volatile bituminous coal from higher CH4-compostion in source gas was found at up to 1O MPa pressure. Preferential adsorp- tion of CO2 increases with increase of CH4 concentration in source gas, and decreases with increasing pressure. Although there was no systematic investigation of the effect of coal rank on preferential adsorp- tion, there are obvious differences in preferential adsorption of gas between low-volatile bituminous coal and anthracite. The obtained preferential adsorption gives rise to the assumption that CO2 sequestration in coal beds with subsequent CO2-ECBM might be an ootion in Qinshui Basins, China.
基金financed by the National Basic Research Program of China (Grant No. 2010CB428502)the National Natural Science Foundation of China (Grant No. 40925015)
文摘A statistical regression downscaling method was used to project future changes in precipitation over eastern China based on Phase 5 of the Coupled Model Intercomparison Project (CMIPS) the Representative Concentration Pathway (RCP) scenarios simulated by the second spectral version of the Flexible Global Ocean- Atmosphere-Land System (FGOALS-s2) model. Our val- idation results show that the downscaled time series agree well with the present observed precipitation in terms of both the annual mean and the seasonal cycle. The regres- sion models built from the historical data are then used to generate future projections. The results show that the en- hanced land-sea thermal contrast strengthens both the subtropical anticyclone over the western Pacific and the east Asian summer monsoon flow under both RCPs. However, the trend of precipitation in response to warming over the 21 st century are different across eastern Chi- na under different RCPs. The area to the north of 32°N is likely to experience an increase in annual mean precipitation, while for the area between 23°N and 32°N mean precipitation is projected to decrease slightly over this century under RCP8.5. The change difference between scenarios mainly exists in the middle and late century. The land-sea thermal contrast and the associated east Asian summer monsoon flow are stronger, such that precipitation increases more, at higher latitudes under RCP8.5 compared to under RCP4.5. For the region south of 32°N, rainfall is projected to increase slightly under RCP4.5 but decrease under RCP8.5 in the late century. At the high resolution of 5 km, our statistically downscaled results for projected precipitation can be used to force hydrological models to project hydrological processes, which will be of great benefit to regional water planning and management.
文摘Low Carbon Employment is an inevitable choice for the purpose of "energy-saving and emission reduction" and "promoting employment". By Multi-variable Linear Backward Regression method, this study presents an empirical analysis of the emplovment impact of policy variables indexes that involves economic pull, industry upgrading, population development, technical inputs and so on. The paper demonstrates that wide range offactors will affect low carbon employment, that industry upgrading will affect how carbon employment remarkably, that to increase years of people education will notably improve low carbon employment level of secondary vocational-technical labor, and that to raise technical inputs will significantly enhance college students' low carbon employment.
基金Under the auspices of National Natural Science Foundation of China(No.41601607,41771138,41771161)Strategic Planning Project from Institute of Northeast Geography and Agroecology(IGA),Chinese Academy of Sciences(No.Y6H2091001-3)
文摘High PM_(2.5) concentrations and frequent air pollution episodes during late autumn and winter in Jilin Province have attracted attention in recent years. To describe the spatial and temporal variations of PM_(2.5) concentrations and identify the decisive influencing factors, a large amount of continuous daily PM_(2.5) concentration data collected from 33 monitoring stations over 2-year period from 2015 to 2016 were analyzed. Meanwhile, the relationships were investigated between PM_(2.5) concentrations and the land cover, socioeconomic and meteorological factors from the macroscopic perspective using multiple linear regressions(MLR) approach. PM_(2.5) concentrations across Jilin Province averaged 49 μg/m^3, nearly 1.5 times of the Chinese annual average standard, and exhibited seasonal patterns with generally higher levels during late autumn and over the long winter than the other seasons. Jilin Province could be divided into three kinds of sub-regions according to 2-year average PM_(2.5) concentration of each city. Most of the spatial variation in PM_(2.5) levels could be explained by forest land area, cultivated land area, urban greening rate, coal consumption and soot emissions of cement manufacturing. In addition, daily PM_(2.5) concentrations had negative correlation with daily precipitation and positive correlation with air pressure for each city, and the spread and dilution effect of wind speed on PM_(2.5) was more obvious at mountainous area in Jilin Province. These results indicated that coal consumption, cement manufacturing and straw burning were the most important emission sources for the high PM_(2.5) levels, while afforestation and urban greening could mitigate particulate air pollution. Meanwhile, the individual meteorological factors such as precipitation, air pressure, wind speed and temperature could influence local PM_(2.5) concentration indirectly.
文摘AIM:To assess the risk of biliary and pancreatic cancers in a large cohort of patients with type 2 diabetes mellitus(DM) .METHODS:Eligibility for this study included patients with type 2 DM(ICD-9 code 250.0) who were discharged from Department of Veteran Affairs hospitals between 1990 and 2000.Non-matched control patients without DM were selected from the same patient treatment files during the same period.Demographic information included age,sex and race.Secondary diagnoses included known risk factors based on their ICD-9 codes.By multivariate logistic regression,the occurrence of biliary and pancreatic cancer was compared between case subjects with DM and controls without DM.RESULTS:A total of 1172496 case and control subjects were analyzed.The mean age for study and control subjects was 65.8 ± 11.3 and 64.8 ± 12.6 years,respectively.The frequency of pancreatic cancer in subjects with DM was increased(0.9%) in comparison to control subjects(0.3%) with an OR of 3.22(95% CI:3.03-3.42) .The incidence of gallbladder andextrahepatic biliary cancers was increased by twofold in diabetic patients when compared to controls.The OR and 95% CI were 2.20(1.56-3.00) and 2.10(1.61-2.53) ,respectively.CONCLUSION:Our study demonstrated that patients with DM have a threefold increased risk for developing pancreatic cancer and a twofold risk for developing biliary cancer.
基金Supported by Shanghai "Phosphor" Science Foundation, China, No. 09QB1403100the National High Technology Researchand Development Program of China, No. 2006AA020704 and 2006AA02A407the Funds for Key Programs of Ministry ofHealth of China, No.2008ZX10002-017
文摘AIM: To explore the association between single nucleotide polymorphisms (SNPs) at 8q24 and gastric cancer risk. METHODS: A case-control investigation including 212 gastric cancer patients and 377 healthy controls was conducted. The genotypes of SNPs (rs6983267, rs7008482 and rs10808555) were examined and established through polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Multivariate logistic regression models were used to evaluate the association between SNPs and gastric cancer. RESULTS: The genotype frequencies of rs6983267 in gastric cancer patients were obviously different from those in the control (P = 0.005). GT genotype of rs6983267 was associated with an increased risk of gastric cancer compared with GG genotype (adjusted odds ratio = 2.01, 95% confidence interval: 1.28-3.14). Further stratified analysis indicated that rs6983267 GT genotype facilitated the risk of gastric cancer of non-cardiac and intestinal type (OR: 2.638, 95% CI: 1.464-4.753; OR: 1.916, 95% CI: 1.166-3.150, respectively). CONCLUSION: This study demonstrates for the first time that rs6983267 is involved in susceptibility to gastric cancer, although further large-sample investigations are still needed.
基金Supported by the National Natural Science Foundation(No.70903072)Shanghai Municipal Health Bureau,Republic of China(No.2008QN013)
文摘Objective:The purpose of the study was to compare the preventive care use and health between the elderly living alone and living with other individuals and identify strategies to improve the preventive care use among the elderly living alone.Methods:A questionnaire including socioeconomic characteristics,preventive care use,health status and Social Support Rate Scale was administered to 240 elderly living alone and 244 elderly living with other individuals in Shanghai,China.Logistic regression analysis was used to examine the predictors of preventive care use.Results:The elderly living alone were more likely to be single(never married,divorced,separated and widowed),have lower social support and income,utilize less routine physical check-up and blood glucose screenings,have worse self-reported health and have limitations in IADL compared to the elderly living with other individuals.Women,old age,high education,income and social support and close to medical institutions were positively associated with routine physical check-up among the elderly.Conclusion:Living alone was associated with less preventive care use and worse health.It was important to provide more social support and economic support for the elderly living alone to increase their preventive health care service utilization and improve their health status.
文摘BackgroundPocket hematoma is one of the major complications associated with cardiovascular implantable electronic devices (CIEDs) implantation. The aim of this study is to evaluate the impact of body mass index (BMI) on the occurrence of pocket hematoma after CIEDs implantation.MethodsThe study is a retrospective review of 972 patients receiving CIEDs implantation between 2008 and 2012 in a tertiary hospital.ResultsTwenty two patients (2.2%) developed severe pocket hematoma requiring re-intervention. The hematoma rate (4.6%,n = 15) of patients with a BMI of 〈 23 kg/m2 was significantly higher compared with that of patients with a BMI of≥23 kg/m2 (1.1%, n = 7,P〈 0.001). In multivariate regression analysis, a BMI 〈 23.0 kg/m2 may be associated with the development of severe pocket hema-toma. An increase of 1.0 kg/m2 in BMI was associated with lower incidence of hematoma formation (OR: 0.84; 95% CI: 0.74-0.95;P = 0.006).ConclusionBMI 〈 23 kg/m2 was associated with a higher incidence of pocket hematoma, requiring re-intervention. The data sup-port that great care must be taken when patients were with a lower BMI received CIEDs implantation.
基金This project was funded by the Department of Science and Technology of China Earthquake Administration
文摘The author carefully selected earthquakes with M_L=4.0~5.0, 215 occurring in the crust in the Taiwan region. The attenuation characteristics of maximum displacement recorded by the Fujian digital network have been obtained by multi-analysis as follows:logA=2.07+231.1/Δ (150km≤Δ≤650km) And the corresponding expression of calibration function is, R(Δ)=3.45-231.1(1/Δ-0.01) (150km≤Δ≤650km) Then, the author determined the magnitude and its error with the data from the Fujian network using the calibration function brought forward in 1997 and the above formula for 790 earthquakes occurring in the crust in the Taiwan region from September 1997 ~ August 2005. The result indicates that the average error of the network is 0.20 with the former and 0.18 with the latter. The average error is 0.13 with the latter with station correction. Compared with the magnitude determined by Taiwan seismologists, the magnitude value with the former is lower by 0.50 on average and that with the latter is higher by 0.08 on average.
基金supported by the open fund of Key Laboratory of Geoscience Spatial Information Technology, Ministry of Land and Resource of the China (Grant No. KLGSIT2013-15)The GIS-studio (www.gis-studio.nl) of the Institute for Biodiversity and Ecosystem Dynamics (IBED) is acknowledged for computational support
文摘Regional Landslide Susceptibility Zonation(LSZ) is always challenged by the available amount of field data, especially in southwestern China where large mountainous areas and limited field information coincide. Statistical learning algorithms are believed to be superior to traditional statistical algorithms for their data adaptability. The aim of the paper is to evaluate how statistical learning algorithms perform on regional LSZ with limited field data. The focus is on three statistical learning algorithms, Logistic Regression(LR), Artificial Neural Networks(ANN) and Support Vector Machine(SVM). Hanzhong city, a landslide prone area in southwestern China is taken as a study case. Nine environmental factors are selected as inputs. The accuracies of the resulting LSZ maps are evaluated through landslide density analysis(LDA), receiver operating characteristic(ROC) curves and Kappa index statistics. The dependence of the algorithm on the size of field samples is examined by varying the sizes of the training set. The SVM has proven to be the most accurate and the most stable algorithm at small training set sizes and on all known landslide sizes. The accuracy of SVM shows a steadilyincreasing trend and reaches a high level at a small size of the training set, while accuracies of LR and ANN algorithms show distinct fluctuations. The geomorphological interpretations confirm the strength of SVM on all landslide sizes. Our results show that the strengths of SVM in generalization capability and model robustness make it an appropriate and efficient tool for regional LSZ with limited landslide field samples.