The C-band synthetic aperture radar（SAR） data from the Bohai Sea of China, the Labrador Sea in the Arctic and the Weddell Sea in the Antarctic are used to analyze and discuss the sea ice full polarimetric informatio...The C-band synthetic aperture radar（SAR） data from the Bohai Sea of China, the Labrador Sea in the Arctic and the Weddell Sea in the Antarctic are used to analyze and discuss the sea ice full polarimetric information reconstruction ability under compact polarimetric modes. The type of compact polarimetric mode which has the highest reconstructed accuracy is analyzed, along with the performance impact of the reconstructed pseudo quad-pol SAR data on the sea ice detection and sea ice classification. According to the assessment and analysis, it is recommended to adopt the CTLR mode for reconstructing the polarimetric parameters σ_（HH）~0,σ_（VV）~0, H and α,while for reconstructing the polarimetric parameters σ_（HV）~0, ρ_（H-V）, λ_1 and λ_2, it is recommended to use the π/4 mode.Moreover, it is recommended to use the π/4 mode in studying the action effects between the electromagnetic waves and sea ice, but it is recommended to use the CTLR mode for studying the sea ice classification.展开更多
Freeze-thaw erosion is the third largest soil erosion type after water erosion and wind erosion. Restricted by many factors, few researches on freeze-thaw erosion have so far been done at home and abroad, especially t...Freeze-thaw erosion is the third largest soil erosion type after water erosion and wind erosion. Restricted by many factors, few researches on freeze-thaw erosion have so far been done at home and abroad, especially those on the assessment method of freeze-thaw erosion. Based on the comprehensive analysis of impact factors of free-thaw erosion, this paper chooses six indexes, including the annual temperature range, annual precipitation, slope, aspect, vegetation and soil, to build the model for relative classification of freeze-thaw erosion using weighted and additive methods, and realizes the relative classification of the freeze-thaw erosion in Tibet with the support of GIS software. Then a synthetic assessment of freeze-thaw erosion in Tibet has been carried out according to the relative classification result. The result shows that the distribution of freeze-thaw eroded area is very extensive in Tibet, accounting for 55.3% of the total local land area; the spatial differentiation of freeze-thaw erosion with different intensities is obvious; and the difference in distribution among different regions is also obvious.展开更多
Since the outbreak of the coronavirus disease 2019(COVID-19)pandemic,over 103214008 cases have been reported,with more than 2231158 deaths as of January 31,2021.Although the gold standard for diagnosis of this disease...Since the outbreak of the coronavirus disease 2019(COVID-19)pandemic,over 103214008 cases have been reported,with more than 2231158 deaths as of January 31,2021.Although the gold standard for diagnosis of this disease remains the reverse-transcription polymerase chain reaction of nasopharyngeal and oropharyngeal swabs,its false-negative rates have ignited the use of medical imaging as an important adjunct or alternative.Medical imaging assists in identifying the pathogenesis,the degree of pulmonary damage,and the characteristic features in each imaging modality.This literature review collates the characteristic radiographic findings of COVID-19 in various imaging modalities while keeping the preliminary focus on chest radiography,computed tomography(CT),and ultrasound scans.Given the higher sensitivity and greater proficiency in detecting characteristic findings during the early stages,CT scans are more reliable in diagnosis and serve as a practical method in following up the disease time course.As research rapidly expands,we have emphasized the CO-RADS classification system as a tool to aid in communicating the likelihood of COVID-19 suspicion among healthcare workers.Additionally,the utilization of other scoring systems such as MuLBSTA,Radiological Assessment of Lung Edema,and Brixia in this pandemic are reviewed as they integrate the radiographic findings into an objective scoring system to risk stratify the patients and predict the severity of disease.Furthermore,current progress in the utilization of artificial intelligence via radiomics is evaluated.Lastly,the lesson from the first wave and preparation for the second wave from the point of view of radiology are summarized.展开更多
Although the development of the 2009 Sp A classification criteria by Assessment of Spondylo Arthritis international Society（ASAS） represents an important step towards a better definition of the early disease stage p...Although the development of the 2009 Sp A classification criteria by Assessment of Spondylo Arthritis international Society（ASAS） represents an important step towards a better definition of the early disease stage particularly in axial spondyloarthritis（ax Sp A）, the specificity of the criteria has been criticized these days. As the commonest zoonotic infection worldwide, human brucellosis can mimic a large number of diseases, including Sp A. This study was performed to determine the frequency of rheumatologic manifestations in patients with brucellosis and the chance of misdiagnosing them as having ax Sp A in central China. The results showed that clinical manifestations of ax Sp A could be observed in brucellosis. Over half of patients had back pain, and one fifth of the patients with back pain were less than 45 years old at onset and had the symptom for more than 3 months. Two young males were falsely classified as suffering from ax Sp A according to the ASAS criteria, and one with MRI proved sacroiliitis was once given Etanercept for treatment. Therefore, differential diagnosis including human brucellosis should always be kept in mind when applying the ASAS criteria, even in traditionally non-endemic areas.展开更多
基金The National Science Foundation for Young Scientists of China under contract No.41306193the National Special Research Fund for Non-profit Marine Sector under contract No.201305025-2the Dragon 3 Cooperation Programme under contract No.10501 by the Ministry of Science and Technology of the P.R.China and the European Space Agency
文摘The C-band synthetic aperture radar（SAR） data from the Bohai Sea of China, the Labrador Sea in the Arctic and the Weddell Sea in the Antarctic are used to analyze and discuss the sea ice full polarimetric information reconstruction ability under compact polarimetric modes. The type of compact polarimetric mode which has the highest reconstructed accuracy is analyzed, along with the performance impact of the reconstructed pseudo quad-pol SAR data on the sea ice detection and sea ice classification. According to the assessment and analysis, it is recommended to adopt the CTLR mode for reconstructing the polarimetric parameters σ_（HH）~0,σ_（VV）~0, H and α,while for reconstructing the polarimetric parameters σ_（HV）~0, ρ_（H-V）, λ_1 and λ_2, it is recommended to use the π/4 mode.Moreover, it is recommended to use the π/4 mode in studying the action effects between the electromagnetic waves and sea ice, but it is recommended to use the CTLR mode for studying the sea ice classification.
基金Key Basic Research Project of China, No.2004CCA03600
文摘Freeze-thaw erosion is the third largest soil erosion type after water erosion and wind erosion. Restricted by many factors, few researches on freeze-thaw erosion have so far been done at home and abroad, especially those on the assessment method of freeze-thaw erosion. Based on the comprehensive analysis of impact factors of free-thaw erosion, this paper chooses six indexes, including the annual temperature range, annual precipitation, slope, aspect, vegetation and soil, to build the model for relative classification of freeze-thaw erosion using weighted and additive methods, and realizes the relative classification of the freeze-thaw erosion in Tibet with the support of GIS software. Then a synthetic assessment of freeze-thaw erosion in Tibet has been carried out according to the relative classification result. The result shows that the distribution of freeze-thaw eroded area is very extensive in Tibet, accounting for 55.3% of the total local land area; the spatial differentiation of freeze-thaw erosion with different intensities is obvious; and the difference in distribution among different regions is also obvious.
文摘Since the outbreak of the coronavirus disease 2019(COVID-19)pandemic,over 103214008 cases have been reported,with more than 2231158 deaths as of January 31,2021.Although the gold standard for diagnosis of this disease remains the reverse-transcription polymerase chain reaction of nasopharyngeal and oropharyngeal swabs,its false-negative rates have ignited the use of medical imaging as an important adjunct or alternative.Medical imaging assists in identifying the pathogenesis,the degree of pulmonary damage,and the characteristic features in each imaging modality.This literature review collates the characteristic radiographic findings of COVID-19 in various imaging modalities while keeping the preliminary focus on chest radiography,computed tomography(CT),and ultrasound scans.Given the higher sensitivity and greater proficiency in detecting characteristic findings during the early stages,CT scans are more reliable in diagnosis and serve as a practical method in following up the disease time course.As research rapidly expands,we have emphasized the CO-RADS classification system as a tool to aid in communicating the likelihood of COVID-19 suspicion among healthcare workers.Additionally,the utilization of other scoring systems such as MuLBSTA,Radiological Assessment of Lung Edema,and Brixia in this pandemic are reviewed as they integrate the radiographic findings into an objective scoring system to risk stratify the patients and predict the severity of disease.Furthermore,current progress in the utilization of artificial intelligence via radiomics is evaluated.Lastly,the lesson from the first wave and preparation for the second wave from the point of view of radiology are summarized.
文摘Although the development of the 2009 Sp A classification criteria by Assessment of Spondylo Arthritis international Society（ASAS） represents an important step towards a better definition of the early disease stage particularly in axial spondyloarthritis（ax Sp A）, the specificity of the criteria has been criticized these days. As the commonest zoonotic infection worldwide, human brucellosis can mimic a large number of diseases, including Sp A. This study was performed to determine the frequency of rheumatologic manifestations in patients with brucellosis and the chance of misdiagnosing them as having ax Sp A in central China. The results showed that clinical manifestations of ax Sp A could be observed in brucellosis. Over half of patients had back pain, and one fifth of the patients with back pain were less than 45 years old at onset and had the symptom for more than 3 months. Two young males were falsely classified as suffering from ax Sp A according to the ASAS criteria, and one with MRI proved sacroiliitis was once given Etanercept for treatment. Therefore, differential diagnosis including human brucellosis should always be kept in mind when applying the ASAS criteria, even in traditionally non-endemic areas.
