BACKGROUND Chronic pancreatitis(CP)is a fibroinflammatory syndrome leading to reduced quality of life and shortened life expectancy.Population-based estimates of the incidence,prevalence,and comorbidities of CP in Chi...BACKGROUND Chronic pancreatitis(CP)is a fibroinflammatory syndrome leading to reduced quality of life and shortened life expectancy.Population-based estimates of the incidence,prevalence,and comorbidities of CP in China are scarce.AIM To characterize the incidence,prevalence,and comorbidities of CP in Sichuan Province,China,with population-based data.METHODS Data on CP from 2015 to 2021 were obtained from the Health Information Center of Sichuan Province.During the study period,a total of 38090 individuals were diagnosed with CP in Sichuan Province.The yearly incidence rate and point prevalence rate(December 31,2021)of CP were calculated.The prevalence of comorbid conditions in CP patients was estimated.The annual number of CPrelated hospitalizations,hospital length of stay,and hospitalization costs for CP were evaluated.Yearly incidence rates were standardized for age by the direct method using the permanent population of Sichuan Province in the 2020 census as the standard population.An analysis of variance test for the linearity of scaled variables and the Cochran-Armitage trend test for categorical data were performed to investigate the yearly trends,and a two-sided test with P<0.05 was considered statistically significant.RESULTS The 38090 CP patients comprised 23280 males and 14810 females.The mean age of patients at CP diagnosis was 57.83 years,with male patients(55.87 years)being younger than female patients(60.11 years)(P<0.001).The mean incidence rate of CP during the study period was 6.81 per 100000 person-years,and the incidence of CP increased each year,from 4.03 per 100000 person-years in 2015 to 8.27 per 100000 person-years in 2021(P<0.001).The point prevalence rate of CP in 2021 was 45.52 per 100000 individuals for the total population,with rates of 55.04 per 100000 individuals for men and 35.78 per 100000 individuals for women(P<0.001).Individuals aged 65 years or older had the highest prevalence of CP(113.38 per 100000 individuals)(P<0.001).Diabetes(26.32%)was the most common comorbidity in CP patients.The number of CP-related hospitalizations increased from 3739 in 2015 to 11009 in 2021.The total costs for CP-related hospitalizations for CP patients over the study period were 667.96 million yuan,with an average of 17538 yuan per patient.CONCLUSION The yearly incidence of CP is increasing,and the overall CP hospitalization cost has increased by 1.4 times during the last 7 years,indicating that CP remains a heavy health burden.展开更多
Background: China is one of the countries with abundant waterbird diversity. Over the past decades, China's waterbirds have suffered increasing threats from direct and indirect human activities. It is important to...Background: China is one of the countries with abundant waterbird diversity. Over the past decades, China's waterbirds have suffered increasing threats from direct and indirect human activities. It is important to clarify the population trends of and threats to waterbirds as well as to put forward conservation recommendations.Methods: We collected data of population trends of a total of 260 waterbird species in China from Wetlands International database. We calculated the number of species with increasing, declining, stable, and unknown trends. We collected threatened levels of waterbirds from the Red List of China's Vertebrates(2016), which was compiled according to the IUCN criteria of threatened species. Based on literature review, we refined the major threats to the threatened waterbird species in China.Results: Of the total 260 waterbird species in China, 84 species(32.3%) exhibited declining, 35 species(13.5%) kept stable, and 16 species(6.2%) showed increasing trends. Population trends were unknown for 125 species(48.1%). There was no significant difference in population trends between the migratory(32.4% decline) and resident(31.8% decline) species or among waterbirds distributed exclusively along coasts(28.6% decline), inland(36.6% decline), and both coasts and inland(32.5% decline). A total of 38 species(15.1% of the total) were listed as threatened species and 27 species(10.8% of the total) Near Threatened species. Habitat loss was the major threat to waterbirds, with 32 of the total 38(84.2%) threatened species being affected. In addition, 73.7%(28 species), 71.1%(27 species), and 57.9%(22 species) of the threatened species were affected by human disturbance, environmental pollution, and illegal hunting, respectively.Conclusions: We propose recommendations for waterbird conservation, including(1) strengthening conservation of nature wetlands and restoration of degraded wetlands,(2) enhancing public awareness on waterbird conservation,(3) improving the enforcement of Wildlife Protection Law and cracking down on illegal hunting,(4) carrying out longterm waterbird surveys to clarify population dynamics,(5) restoring populations of highly-threatened species through artificial intervention, and(6) promoting international and regional exchanges and cooperation to share information in waterbirds and their conservation.展开更多
Oculocutaneous albinism (OCA)is an autosomal recessive pigmentation abnormality,characterized by variable hair,skin,and ocular hypopigmentation.OCA1 is the most frequent subtype of OCA,caused by mutations in the tyros...Oculocutaneous albinism (OCA)is an autosomal recessive pigmentation abnormality,characterized by variable hair,skin,and ocular hypopigmentation.OCA1 is the most frequent subtype of OCA,caused by mutations in the tyrosinase gene (TYR). In this study,we investigated the genetic mutation of a Chinese family with a female OCA patient who came for genetic counseling before pregnancy.Complete physical examination was performed,and DNA from blood samples was collected from the family members.Mutations of TYR,OCA2,and SLC45A2 genes were examined in the proband, and verified in her parents by Sanger sequencing.Large deletion or duplication of TYR and OCA2 genes was detected by multiplex ligation-dependent probe amplification (MLPA).A homozygous TYR c.307T>C (p.Cys103Arg)missense mutation was identified in the proband,and both parents were heterozygous carriers.No large deletion or duplication was found in the proband.This mutation was absent in 1000G,ExAC,or HGMD database,and multiple lines of in silico tools supported a deleterious effect.These results suggest that TYR c.307T>C mutation might be responsible for OCA1,and our study further expands the mutation spectrum of OCA1 in the Chinese population.展开更多
Background: Departure decisions and behaviors of migratory birds at stopover sites are expected to maximize fit?ness by trade?offs among avoiding predators, optimizing refueling(energy) capacity, and matching other li...Background: Departure decisions and behaviors of migratory birds at stopover sites are expected to maximize fit?ness by trade?offs among avoiding predators, optimizing refueling(energy) capacity, and matching other life?history events. We predict that species with different body sizes and migratory destinations will exhibit different behaviors when departing from the same stopover site. We also predict that with strong time constraint at the final pre?breed?ing stopover site, departure decisions may be less sensitive to exogenous factors, such as wind condition, compared to other stopover or nonbreeding sites.Methods: We recorded migratory departures of four shorebird species, i.e. Eurasian Curlew(Numenius arquata), Bar?tailed Godwit(Limosa lapponica), Great Knot(Calidris tenuirostris), and Grey Plover(Pluvialis squatarola), at Yaluji?ang Estuary Wetlands in China, a final pre?breeding stopover site in the northern Yellow Sea, from 2011 to 2014. We compared flock sizes, departure time and departure directions between species, and investigated the effects of tide and weather conditions(rain and ground wind speed and direction) on the departure decision of shorebirds.Results: We found that larger species departed in smaller flocks and were more variable in daily departure time. Departure trajectory of all four species appeared to be influenced by coastal topography. With the east–west coast?line and intertidal mudflat on the south, birds exhibited westward or eastward deflection from the shortest migra?tory routes. Bar?tailed Godwit was the only species that deviated to the southeast and did not climb over the land. Birds avoided departure during precipitation, while their departure was not related to ground wind benefit or tidal condition.Conclusions: Body size among species, which influences their vulnerability to predators, might be important in shaping shorebird departure strategies. Diverse departure directions could be the result of different wind use tac?tics in climbing stage. Narrow optimal time window of breeding might lead to reduced flexibility in departure date at a final pre?breeding site. Both endogenous and exogenous are important in shaping departure behaviors and decisions.展开更多
African swine fever virus(ASFV)infects domestic pigs and European wild boars with strong,hemorrhagic and high mortality.The primary cellular targets of ASFV is the porcine macrophages.Up to now,no commercial vaccine o...African swine fever virus(ASFV)infects domestic pigs and European wild boars with strong,hemorrhagic and high mortality.The primary cellular targets of ASFV is the porcine macrophages.Up to now,no commercial vaccine or effective treatment available to control the disease.In this study,three recombinant Saccharomyces cerevisiae(S.cerevisiae)strains expressing fused ASFV proteins-porcine Ig heavy chains were constructed and the immunogenicity of the S.cerevisiae-vectored cocktail ASFV feeding vaccine was further evaluated.To be specific,the P30-Fcγand P54-Fcαfusion proteins displaying on surface of S.cerevisiae cells were produced by fusing the Fc fragment of porcine immunoglobulin IgG1 or IgA1 with p30 or p54 gene of ASFV respectively.The recombinant P30-Fcγand P54-Fcαfusion proteins expressed by S.cerevisiae were verified by Western blotting,flow cytometry and immunofluorescence assay.Porcine immunoglobulin Fc fragment fused P30/P54 proteins elicited P30/P54-specific antibody production and induced higher mucosal immunity in swine.The absorption and phagocytosis of recombinant S.cerevisiae strains in IPEC-J2 cells or porcine alveolar macrophage(PAM)cells were significantly enhanced,too.Here,we introduce a kind of cheap and safe oral S.cerevisiae-vectored vaccine,which could activate the specific mucosal immunity for controlling ASFV infection.展开更多
Procalcitonin(PCT),C-reactive protein(CRP),and white blood cell(WBC)have been used as markers of bacterial infection in children for decades.Previous studies have suggested PCT,CRP,WBC,and percentage of neutrophils(%N...Procalcitonin(PCT),C-reactive protein(CRP),and white blood cell(WBC)have been used as markers of bacterial infection in children for decades.Previous studies have suggested PCT,CRP,WBC,and percentage of neutrophils(%N)may be useful in detecting bacterial infection in children[1-4].However,elevated levels of these biomarkers have also been noted in children with enterovirus infection[5-7].In a study involving 5692 hospitalized children with herpangina or hand,foot,and mouth disease(HFMD)in two periods of years,the medians of CRP were 50.1 and 42.5 mg/L,respectively.展开更多
An improved Carnegie Ames Stanford Approach （CASA） model based on two kinds of remote sensing （RS） data, Landsat Enhanced Thematic Mapper Plus （ETM ＋） and Moderate Resolution Imaging Spectro- radiometer （MODIS...An improved Carnegie Ames Stanford Approach （CASA） model based on two kinds of remote sensing （RS） data, Landsat Enhanced Thematic Mapper Plus （ETM ＋） and Moderate Resolution Imaging Spectro- radiometer （MODIS）, and climate variables were applied to estimate the Net Primary Productivity （NPP） of Xuzhou in June of each year from 2001 to 2010. The NPP of the study area decreased as the spatial scale increased. The average NPP of terrestrial vegetation in Xuzhou showed a decreasing trend in recent years, likely due to changes in climate and environment. The study area was divided into four sub-regions, designated as highest, moderately high, moderately low, and lowest in NPR The area designated as the lowest sub-region in NPP increased with expanding scale, indicating that the NPP distribution varied with different spatial scales. The NPP of different vegetation types was also significantly influenced by scale. In particular, the NPP of urban woodland produced lower estimates because of mixed pixels. Similar trends in NPP were observed with different RS data. In addition, expansion of residential areas and reduction of vegetated areas were the major reasons for NPP change. Land cover changes in urban areas reduced NPP, which could chiefly be attributed to human-induced disturbance.展开更多
Conventional change detection approaches are mainly based on per-pixel processing,which ignore the sub-pixel spectral variation resulted from spectral mixture.Especially for medium-resolution remote sensing images use...Conventional change detection approaches are mainly based on per-pixel processing,which ignore the sub-pixel spectral variation resulted from spectral mixture.Especially for medium-resolution remote sensing images used in urban landcover change monitoring,land use/cover components within a single pixel are usually complicated and heterogeneous due to the limitation of the spatial resolution.Thus,traditional hard detection methods based on pure pixel assumption may lead to a high level of omission and commission errors inevitably,degrading the overall accuracy of change detection.In order to address this issue and find a possible way to exploit the spectral variation in a sub-pixel level,a novel change detection scheme is designed based on the spectral mixture analysis and decision-level fusion.Nonlinear spectral mixture model is selected for spectral unmixing,and change detection is implemented in a sub-pixel level by investigating the inner-pixel subtle changes and combining multiple composition evidences.The proposed method is tested on multi-temporal Landsat Thematic Mapper and China–Brazil Earth Resources Satellite remote sensing images for the land-cover change detection over urban areas.The effectiveness of the proposed approach is confirmed in terms of several accuracy indices in contrast with two pixel-based change detection methods(i.e.change vector analysis and principal component analysis-based method).In particular,the proposed sub-pixel change detection approach not only provides the binary change information,but also obtains the characterization about change direction and intensity,which greatly extends the semantic meaning of the detected change targets.展开更多
A method for the retrieval of land surface temperature （LST） from the two thermal bands of Landsat 8 data is proposed in this paper. The emissivities of vegetation, bare land, buildings, and water are estimated usin...A method for the retrieval of land surface temperature （LST） from the two thermal bands of Landsat 8 data is proposed in this paper. The emissivities of vegetation, bare land, buildings, and water are estimated using different features of the wavelength ranges and spectral response functions. Based on the Planck function of the Thermal Infrared Sensor （TIRS） band 10 and band 11, the radiative transfer equation is rebuilt and the LST is obtained using the modified emissivity parameters. A sensitivity analysis for the LST retrieval is also conducted. The LST was retrieved from Landsat 8 data for the city of Zoucheng, Shandong Province, China, using the proposed algorithm, and the LST reference data were obtained at the same time from a geosensor network （GSN）. A comparative analysis was conducted between the retrieved LST and the reference data from the GSN. The results showed that water had a higher LST error than the other land-cover types, of less than 1.2℃, and the LST errors for buildings and vegetation were less than 0.75℃. The difference between the retrieved LST and reference data was about 1℃ on a clear day. These results confirm that the proposed algorithm is effective for the retrieval of LST from the Landsat 8 thermal bands, and a GSN is an effective way to validate and improve the performance of LST retrieval.展开更多
基金the Special Project on“Digital Development of Health”of the Health Information Center of Sichuan Province,China,No.2021ZXKY06007the National Natural Science Fund of China,No.82241054 and 82000613。
文摘BACKGROUND Chronic pancreatitis(CP)is a fibroinflammatory syndrome leading to reduced quality of life and shortened life expectancy.Population-based estimates of the incidence,prevalence,and comorbidities of CP in China are scarce.AIM To characterize the incidence,prevalence,and comorbidities of CP in Sichuan Province,China,with population-based data.METHODS Data on CP from 2015 to 2021 were obtained from the Health Information Center of Sichuan Province.During the study period,a total of 38090 individuals were diagnosed with CP in Sichuan Province.The yearly incidence rate and point prevalence rate(December 31,2021)of CP were calculated.The prevalence of comorbid conditions in CP patients was estimated.The annual number of CPrelated hospitalizations,hospital length of stay,and hospitalization costs for CP were evaluated.Yearly incidence rates were standardized for age by the direct method using the permanent population of Sichuan Province in the 2020 census as the standard population.An analysis of variance test for the linearity of scaled variables and the Cochran-Armitage trend test for categorical data were performed to investigate the yearly trends,and a two-sided test with P<0.05 was considered statistically significant.RESULTS The 38090 CP patients comprised 23280 males and 14810 females.The mean age of patients at CP diagnosis was 57.83 years,with male patients(55.87 years)being younger than female patients(60.11 years)(P<0.001).The mean incidence rate of CP during the study period was 6.81 per 100000 person-years,and the incidence of CP increased each year,from 4.03 per 100000 person-years in 2015 to 8.27 per 100000 person-years in 2021(P<0.001).The point prevalence rate of CP in 2021 was 45.52 per 100000 individuals for the total population,with rates of 55.04 per 100000 individuals for men and 35.78 per 100000 individuals for women(P<0.001).Individuals aged 65 years or older had the highest prevalence of CP(113.38 per 100000 individuals)(P<0.001).Diabetes(26.32%)was the most common comorbidity in CP patients.The number of CP-related hospitalizations increased from 3739 in 2015 to 11009 in 2021.The total costs for CP-related hospitalizations for CP patients over the study period were 667.96 million yuan,with an average of 17538 yuan per patient.CONCLUSION The yearly incidence of CP is increasing,and the overall CP hospitalization cost has increased by 1.4 times during the last 7 years,indicating that CP remains a heavy health burden.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.31572280 and 31071939)
文摘Background: China is one of the countries with abundant waterbird diversity. Over the past decades, China's waterbirds have suffered increasing threats from direct and indirect human activities. It is important to clarify the population trends of and threats to waterbirds as well as to put forward conservation recommendations.Methods: We collected data of population trends of a total of 260 waterbird species in China from Wetlands International database. We calculated the number of species with increasing, declining, stable, and unknown trends. We collected threatened levels of waterbirds from the Red List of China's Vertebrates(2016), which was compiled according to the IUCN criteria of threatened species. Based on literature review, we refined the major threats to the threatened waterbird species in China.Results: Of the total 260 waterbird species in China, 84 species(32.3%) exhibited declining, 35 species(13.5%) kept stable, and 16 species(6.2%) showed increasing trends. Population trends were unknown for 125 species(48.1%). There was no significant difference in population trends between the migratory(32.4% decline) and resident(31.8% decline) species or among waterbirds distributed exclusively along coasts(28.6% decline), inland(36.6% decline), and both coasts and inland(32.5% decline). A total of 38 species(15.1% of the total) were listed as threatened species and 27 species(10.8% of the total) Near Threatened species. Habitat loss was the major threat to waterbirds, with 32 of the total 38(84.2%) threatened species being affected. In addition, 73.7%(28 species), 71.1%(27 species), and 57.9%(22 species) of the threatened species were affected by human disturbance, environmental pollution, and illegal hunting, respectively.Conclusions: We propose recommendations for waterbird conservation, including(1) strengthening conservation of nature wetlands and restoration of degraded wetlands,(2) enhancing public awareness on waterbird conservation,(3) improving the enforcement of Wildlife Protection Law and cracking down on illegal hunting,(4) carrying out longterm waterbird surveys to clarify population dynamics,(5) restoring populations of highly-threatened species through artificial intervention, and(6) promoting international and regional exchanges and cooperation to share information in waterbirds and their conservation.
基金This project was supported by the National Natural Science Foundation of China (No.81500925).
文摘Oculocutaneous albinism (OCA)is an autosomal recessive pigmentation abnormality,characterized by variable hair,skin,and ocular hypopigmentation.OCA1 is the most frequent subtype of OCA,caused by mutations in the tyrosinase gene (TYR). In this study,we investigated the genetic mutation of a Chinese family with a female OCA patient who came for genetic counseling before pregnancy.Complete physical examination was performed,and DNA from blood samples was collected from the family members.Mutations of TYR,OCA2,and SLC45A2 genes were examined in the proband, and verified in her parents by Sanger sequencing.Large deletion or duplication of TYR and OCA2 genes was detected by multiplex ligation-dependent probe amplification (MLPA).A homozygous TYR c.307T>C (p.Cys103Arg)missense mutation was identified in the proband,and both parents were heterozygous carriers.No large deletion or duplication was found in the proband.This mutation was absent in 1000G,ExAC,or HGMD database,and multiple lines of in silico tools supported a deleterious effect.These results suggest that TYR c.307T>C mutation might be responsible for OCA1,and our study further expands the mutation spectrum of OCA1 in the Chinese population.
基金financially supported by the National Natural Science Foundation of China(31071939,31572280,and 31772467)
文摘Background: Departure decisions and behaviors of migratory birds at stopover sites are expected to maximize fit?ness by trade?offs among avoiding predators, optimizing refueling(energy) capacity, and matching other life?history events. We predict that species with different body sizes and migratory destinations will exhibit different behaviors when departing from the same stopover site. We also predict that with strong time constraint at the final pre?breed?ing stopover site, departure decisions may be less sensitive to exogenous factors, such as wind condition, compared to other stopover or nonbreeding sites.Methods: We recorded migratory departures of four shorebird species, i.e. Eurasian Curlew(Numenius arquata), Bar?tailed Godwit(Limosa lapponica), Great Knot(Calidris tenuirostris), and Grey Plover(Pluvialis squatarola), at Yaluji?ang Estuary Wetlands in China, a final pre?breeding stopover site in the northern Yellow Sea, from 2011 to 2014. We compared flock sizes, departure time and departure directions between species, and investigated the effects of tide and weather conditions(rain and ground wind speed and direction) on the departure decision of shorebirds.Results: We found that larger species departed in smaller flocks and were more variable in daily departure time. Departure trajectory of all four species appeared to be influenced by coastal topography. With the east–west coast?line and intertidal mudflat on the south, birds exhibited westward or eastward deflection from the shortest migra?tory routes. Bar?tailed Godwit was the only species that deviated to the southeast and did not climb over the land. Birds avoided departure during precipitation, while their departure was not related to ground wind benefit or tidal condition.Conclusions: Body size among species, which influences their vulnerability to predators, might be important in shaping shorebird departure strategies. Diverse departure directions could be the result of different wind use tac?tics in climbing stage. Narrow optimal time window of breeding might lead to reduced flexibility in departure date at a final pre?breeding site. Both endogenous and exogenous are important in shaping departure behaviors and decisions.
基金supported by the National Key Research and Development Program of China (2018YFD0500500)。
文摘African swine fever virus(ASFV)infects domestic pigs and European wild boars with strong,hemorrhagic and high mortality.The primary cellular targets of ASFV is the porcine macrophages.Up to now,no commercial vaccine or effective treatment available to control the disease.In this study,three recombinant Saccharomyces cerevisiae(S.cerevisiae)strains expressing fused ASFV proteins-porcine Ig heavy chains were constructed and the immunogenicity of the S.cerevisiae-vectored cocktail ASFV feeding vaccine was further evaluated.To be specific,the P30-Fcγand P54-Fcαfusion proteins displaying on surface of S.cerevisiae cells were produced by fusing the Fc fragment of porcine immunoglobulin IgG1 or IgA1 with p30 or p54 gene of ASFV respectively.The recombinant P30-Fcγand P54-Fcαfusion proteins expressed by S.cerevisiae were verified by Western blotting,flow cytometry and immunofluorescence assay.Porcine immunoglobulin Fc fragment fused P30/P54 proteins elicited P30/P54-specific antibody production and induced higher mucosal immunity in swine.The absorption and phagocytosis of recombinant S.cerevisiae strains in IPEC-J2 cells or porcine alveolar macrophage(PAM)cells were significantly enhanced,too.Here,we introduce a kind of cheap and safe oral S.cerevisiae-vectored vaccine,which could activate the specific mucosal immunity for controlling ASFV infection.
基金This work was supported by Shenzhen Fund for Guangdong Provincial High-level Clinical Key Specialties[SZGSP012]Project of the Expert Committee on Clinical Application and Drug Resistance Evaluation of Antimicrobial Drugs of the National Health Commission(KJYWZWH-OT-02-2021-01).
文摘Procalcitonin(PCT),C-reactive protein(CRP),and white blood cell(WBC)have been used as markers of bacterial infection in children for decades.Previous studies have suggested PCT,CRP,WBC,and percentage of neutrophils(%N)may be useful in detecting bacterial infection in children[1-4].However,elevated levels of these biomarkers have also been noted in children with enterovirus infection[5-7].In a study involving 5692 hospitalized children with herpangina or hand,foot,and mouth disease(HFMD)in two periods of years,the medians of CRP were 50.1 and 42.5 mg/L,respectively.
文摘An improved Carnegie Ames Stanford Approach （CASA） model based on two kinds of remote sensing （RS） data, Landsat Enhanced Thematic Mapper Plus （ETM ＋） and Moderate Resolution Imaging Spectro- radiometer （MODIS）, and climate variables were applied to estimate the Net Primary Productivity （NPP） of Xuzhou in June of each year from 2001 to 2010. The NPP of the study area decreased as the spatial scale increased. The average NPP of terrestrial vegetation in Xuzhou showed a decreasing trend in recent years, likely due to changes in climate and environment. The study area was divided into four sub-regions, designated as highest, moderately high, moderately low, and lowest in NPR The area designated as the lowest sub-region in NPP increased with expanding scale, indicating that the NPP distribution varied with different spatial scales. The NPP of different vegetation types was also significantly influenced by scale. In particular, the NPP of urban woodland produced lower estimates because of mixed pixels. Similar trends in NPP were observed with different RS data. In addition, expansion of residential areas and reduction of vegetated areas were the major reasons for NPP change. Land cover changes in urban areas reduced NPP, which could chiefly be attributed to human-induced disturbance.
基金partially supported by the National Natural Science Foundation of China(No.41171323)Jiangsu Provincial Natural Science Foundation(No.BK2012018)+2 种基金the Key Laboratory of Geo-Informatics of National Administration of Surveying,Mapping and Geoinformation of China(No.201109)partially supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)the Fundamental Research Funds for the Central Universities.
文摘Conventional change detection approaches are mainly based on per-pixel processing,which ignore the sub-pixel spectral variation resulted from spectral mixture.Especially for medium-resolution remote sensing images used in urban landcover change monitoring,land use/cover components within a single pixel are usually complicated and heterogeneous due to the limitation of the spatial resolution.Thus,traditional hard detection methods based on pure pixel assumption may lead to a high level of omission and commission errors inevitably,degrading the overall accuracy of change detection.In order to address this issue and find a possible way to exploit the spectral variation in a sub-pixel level,a novel change detection scheme is designed based on the spectral mixture analysis and decision-level fusion.Nonlinear spectral mixture model is selected for spectral unmixing,and change detection is implemented in a sub-pixel level by investigating the inner-pixel subtle changes and combining multiple composition evidences.The proposed method is tested on multi-temporal Landsat Thematic Mapper and China–Brazil Earth Resources Satellite remote sensing images for the land-cover change detection over urban areas.The effectiveness of the proposed approach is confirmed in terms of several accuracy indices in contrast with two pixel-based change detection methods(i.e.change vector analysis and principal component analysis-based method).In particular,the proposed sub-pixel change detection approach not only provides the binary change information,but also obtains the characterization about change direction and intensity,which greatly extends the semantic meaning of the detected change targets.
基金Acknowledgements The authors would like to thank Professors Dengsheng Lu and Wengfeng Zhan for their highly constructive remarks. This research was supported in part by the National Natural Science Foundation of China （Grant No. 41471356）, the Fundamental Research Funds for the Central Universities （2014QNA33）, and the Priority Academic Program Development of Jiangsu Higher Education Institutions. The authors would also like to thank the Jiangsu Innovation Team at CUMT and MASTRO.
文摘A method for the retrieval of land surface temperature （LST） from the two thermal bands of Landsat 8 data is proposed in this paper. The emissivities of vegetation, bare land, buildings, and water are estimated using different features of the wavelength ranges and spectral response functions. Based on the Planck function of the Thermal Infrared Sensor （TIRS） band 10 and band 11, the radiative transfer equation is rebuilt and the LST is obtained using the modified emissivity parameters. A sensitivity analysis for the LST retrieval is also conducted. The LST was retrieved from Landsat 8 data for the city of Zoucheng, Shandong Province, China, using the proposed algorithm, and the LST reference data were obtained at the same time from a geosensor network （GSN）. A comparative analysis was conducted between the retrieved LST and the reference data from the GSN. The results showed that water had a higher LST error than the other land-cover types, of less than 1.2℃, and the LST errors for buildings and vegetation were less than 0.75℃. The difference between the retrieved LST and reference data was about 1℃ on a clear day. These results confirm that the proposed algorithm is effective for the retrieval of LST from the Landsat 8 thermal bands, and a GSN is an effective way to validate and improve the performance of LST retrieval.
