Because of cloudy and rainy weather in south China, optical remote sens-ing images often can＇t be obtained easily. With the regional trial results in Baoying, Jiangsu province, this paper explored the fusion model an...Because of cloudy and rainy weather in south China, optical remote sens-ing images often can＇t be obtained easily. With the regional trial results in Baoying, Jiangsu province, this paper explored the fusion model and effect of ENVISAT/SAR and HJ-1A satel ite multispectral remote sensing images. Based on the ARSIS strat-egy, using the wavelet transform and the Interaction between the Band Structure Model （IBSM）, the research progressed the ENVISAT satel ite SAR and the HJ-1A satel ite CCD images wavelet decomposition, and low/high frequency coefficient re-construction, and obtained the fusion images through the inverse wavelet transform. In the light of low and high-frequency images have different characteristics in differ-ent areas, different fusion rules which can enhance the integration process of self-adaptive were taken, with comparisons with the PCA transformation, IHS transfor-mation and other traditional methods by subjective and the corresponding quantita-tive evaluation. Furthermore, the research extracted the bands and NDVI values around the fusion with GPS samples, analyzed and explained the fusion effect. The results showed that the spectral distortion of wavelet fusion, IHS transform, PCA transform images was 0.101 6, 0.326 1 and 1.277 2, respectively and entropy was 14.701 5, 11.899 3 and 13.229 3, respectively, the wavelet fusion is the highest. The method of wavelet maintained good spectral capability, and visual effects while improved the spatial resolution, the information interpretation effect was much better than other two methods.展开更多
In this letter, a simple and efficient method of image speckle reduction for polari- metric SAR is put forward. It is based on the fast fixed-point ICA (Independent Component Analysis) algorithm of orthogonal and symm...In this letter, a simple and efficient method of image speckle reduction for polari- metric SAR is put forward. It is based on the fast fixed-point ICA (Independent Component Analysis) algorithm of orthogonal and symmetric matrix. Simulation experiment is carried out to separate speckle noise from the polarimetric SAR images, and it indicates that this algorithm has high convergency speed and stability, the image speckle noise is reduced effectively and the speckle index is low, and the image quality is improved obviously.展开更多
One of the major obstacles facing the field of structural biology in the post genomic era is the inherent difficulty of analyzing the structure of membrane proteins under native conditions. The method of choice for st...One of the major obstacles facing the field of structural biology in the post genomic era is the inherent difficulty of analyzing the structure of membrane proteins under native conditions. The method of choice for studying such proteins is FTIR spectroscopy. Following the outbreaking of the severe acute respiratory syndrome （SARS） virus, in 2003, extensive work has been directed at elucidating the structure of the E transmembrane proteins of the SARS coronavirus. In this study, the secondary structure of the transmembrane a-helical bundles was analysised using the biophysical method site specific infrared dichroism （SSID）. Sixteen amino acids were isotopically labeled with （~3C=180） at different positions of the primary structure of the synthesized E protein CoV. The secondary structure was studied using Attenuated Total Internal Reflection （ATR） FTIR spectroscopy. Based on our findings, the presence of two possible H-bonding interactions between the carbonyl oxygen of two residues 26 and 31 （Phe and Leu） respectively with water molecules which may be trapped within the helix structure were postulatesed. These interactions may cause a change in this structure.展开更多
Background:The proportion of recurrences after discharge among patients with coronavirus disease 2019(COVID-19)was reported to be between 9.1%and 31.0%.Little is known about this issue,however,so we performed a meta-a...Background:The proportion of recurrences after discharge among patients with coronavirus disease 2019(COVID-19)was reported to be between 9.1%and 31.0%.Little is known about this issue,however,so we performed a meta-analysis to summarize the demographical,clinical,and laboratorial characteristics of non-recurrence and recurrence groups.Methods:Comprehensive searches were conducted using eight electronic databases.Data re-garding the demographic,clinical,and laboratorial characteristics of both recurrence and non-recurrence groups were extracted,and quantitative and qualitative analyses were conducted.Results:Ten studies involving 2071 COVID-19 cases were included in this analysis.The proportion of recurrence cases involving patients with COVID-19 was 17.65%(between 12.38%and 25.16%)while older patients were more likely to experience recurrence(weighted mean difference(WMD)=1.67,range between 0.08 and 3.26).The time from discharge to recurrence was 13.38 d(between 12.08 and 14.69 d).Patients were categorized as having moderate severity(odds ratio(OR)=2.69,range between 1.30 and 5.58),while those with clinical symptoms including cough(OR=5.52,range between 3.18 and 9.60),sputum production(OR=5.10,range between 2.60 and 9.97),headache(OR=3.57,range between 1.36 and 9.35),and diz-ziness(OR=3.17,range between 1.12 and 8.96)were more likely to be associated with recurrence.Patients pre-senting with bilateral pulmonary infiltration and decreased leucocyte,platelet,and CD4+T counts were at risk of COVID-19 recurrence(OR=1.71,range between 1.07 and 2.75;WMD=?1.06,range between?1.55 and?0.57,WMD=?40.39,range between?80.20 and?0.48,and WMD=?55.26,range between?105.92 and?4.60,respectively).Conclusions:The main factors associated with the recurrence of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)after hospital discharge were older age,moderate severity,bilateral pulmonary infiltration,laboratory findings including decreased leucocytes,platelets,and CD4+T counts,and clinical symptoms including cough,sputum production,headache,and dizziness.These factors can be considered warning indicators for the recurrence of SARS-CoV-2 and might help the development of specific management strategies.展开更多
For the high-resolution airborne synthetic aperture radar （SAR） stereo geolocation application, the final geolocation ac- curacy is influenced by various error parameter sources. In this paper, an airborne SAR stere...For the high-resolution airborne synthetic aperture radar （SAR） stereo geolocation application, the final geolocation ac- curacy is influenced by various error parameter sources. In this paper, an airborne SAR stereo geolocation parameter error model, involving the parameter errors derived from the navigation system on the flight platform, has been put forward. Moreover, a kind of near-direct method for modeling and sensitivity analysis of navigation parameter errors is also given. This method directly uses the ground reference to calculate the covariance matrix relationship between the parameter errors and the eventual geoloeation errors for ground target points. In addition, utilizing true flight track parameters＇ errors, this paper gave a verification of the method and a corresponding sensitivity analysis for airborne SAR stereo geolocation model and proved its efficiency.展开更多
The accuracy of spatial forecasting is close relation to the selection of spatial forecasting model. Each model from special aspects using special spatial data has its own advantage or disadvantage. A more accurate sp...The accuracy of spatial forecasting is close relation to the selection of spatial forecasting model. Each model from special aspects using special spatial data has its own advantage or disadvantage. A more accurate spatial forecasting model can be obtained by a linear combination of some models. In this study, first-order spatial autoregressive （SAR（1）） model, Kriging algorithm interpolation （KAI） model and back-propagation neural network （BPNN） model are established by using cross-section data or time series data. A spatial linear combination forecasting （SLCF） model is obtained by the combination models mentioned above. An empirical research by these models is carried out with forecasting some areas＇ GDP per capita in Fujian, 2003. It is found that the best one is the SLCF model.展开更多
基金supported by the National Natural Science Foundation of China(41171336)the Project of Jiangsu Province Agricultural Science and Technology Innovation Fund(CX12-3054)
文摘Because of cloudy and rainy weather in south China, optical remote sens-ing images often can＇t be obtained easily. With the regional trial results in Baoying, Jiangsu province, this paper explored the fusion model and effect of ENVISAT/SAR and HJ-1A satel ite multispectral remote sensing images. Based on the ARSIS strat-egy, using the wavelet transform and the Interaction between the Band Structure Model （IBSM）, the research progressed the ENVISAT satel ite SAR and the HJ-1A satel ite CCD images wavelet decomposition, and low/high frequency coefficient re-construction, and obtained the fusion images through the inverse wavelet transform. In the light of low and high-frequency images have different characteristics in differ-ent areas, different fusion rules which can enhance the integration process of self-adaptive were taken, with comparisons with the PCA transformation, IHS transfor-mation and other traditional methods by subjective and the corresponding quantita-tive evaluation. Furthermore, the research extracted the bands and NDVI values around the fusion with GPS samples, analyzed and explained the fusion effect. The results showed that the spectral distortion of wavelet fusion, IHS transform, PCA transform images was 0.101 6, 0.326 1 and 1.277 2, respectively and entropy was 14.701 5, 11.899 3 and 13.229 3, respectively, the wavelet fusion is the highest. The method of wavelet maintained good spectral capability, and visual effects while improved the spatial resolution, the information interpretation effect was much better than other two methods.
基金Supported by the University Doctorate Special Research Fund (No.20030614001).
文摘In this letter, a simple and efficient method of image speckle reduction for polari- metric SAR is put forward. It is based on the fast fixed-point ICA (Independent Component Analysis) algorithm of orthogonal and symmetric matrix. Simulation experiment is carried out to separate speckle noise from the polarimetric SAR images, and it indicates that this algorithm has high convergency speed and stability, the image speckle noise is reduced effectively and the speckle index is low, and the image quality is improved obviously.
文摘One of the major obstacles facing the field of structural biology in the post genomic era is the inherent difficulty of analyzing the structure of membrane proteins under native conditions. The method of choice for studying such proteins is FTIR spectroscopy. Following the outbreaking of the severe acute respiratory syndrome （SARS） virus, in 2003, extensive work has been directed at elucidating the structure of the E transmembrane proteins of the SARS coronavirus. In this study, the secondary structure of the transmembrane a-helical bundles was analysised using the biophysical method site specific infrared dichroism （SSID）. Sixteen amino acids were isotopically labeled with （~3C=180） at different positions of the primary structure of the synthesized E protein CoV. The secondary structure was studied using Attenuated Total Internal Reflection （ATR） FTIR spectroscopy. Based on our findings, the presence of two possible H-bonding interactions between the carbonyl oxygen of two residues 26 and 31 （Phe and Leu） respectively with water molecules which may be trapped within the helix structure were postulatesed. These interactions may cause a change in this structure.
基金Project supported by the National Science and Technology Major Project of China(Nos.2018ZX10302206 , 2017ZX10202203)the Zhejiang University Academic Award for Outstanding Doctoral Candidates(No.2020052),China。
文摘Background:The proportion of recurrences after discharge among patients with coronavirus disease 2019(COVID-19)was reported to be between 9.1%and 31.0%.Little is known about this issue,however,so we performed a meta-analysis to summarize the demographical,clinical,and laboratorial characteristics of non-recurrence and recurrence groups.Methods:Comprehensive searches were conducted using eight electronic databases.Data re-garding the demographic,clinical,and laboratorial characteristics of both recurrence and non-recurrence groups were extracted,and quantitative and qualitative analyses were conducted.Results:Ten studies involving 2071 COVID-19 cases were included in this analysis.The proportion of recurrence cases involving patients with COVID-19 was 17.65%(between 12.38%and 25.16%)while older patients were more likely to experience recurrence(weighted mean difference(WMD)=1.67,range between 0.08 and 3.26).The time from discharge to recurrence was 13.38 d(between 12.08 and 14.69 d).Patients were categorized as having moderate severity(odds ratio(OR)=2.69,range between 1.30 and 5.58),while those with clinical symptoms including cough(OR=5.52,range between 3.18 and 9.60),sputum production(OR=5.10,range between 2.60 and 9.97),headache(OR=3.57,range between 1.36 and 9.35),and diz-ziness(OR=3.17,range between 1.12 and 8.96)were more likely to be associated with recurrence.Patients pre-senting with bilateral pulmonary infiltration and decreased leucocyte,platelet,and CD4+T counts were at risk of COVID-19 recurrence(OR=1.71,range between 1.07 and 2.75;WMD=?1.06,range between?1.55 and?0.57,WMD=?40.39,range between?80.20 and?0.48,and WMD=?55.26,range between?105.92 and?4.60,respectively).Conclusions:The main factors associated with the recurrence of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)after hospital discharge were older age,moderate severity,bilateral pulmonary infiltration,laboratory findings including decreased leucocytes,platelets,and CD4+T counts,and clinical symptoms including cough,sputum production,headache,and dizziness.These factors can be considered warning indicators for the recurrence of SARS-CoV-2 and might help the development of specific management strategies.
基金Supported by the National Basic Research Program of China (No. 2006CB701303)
文摘For the high-resolution airborne synthetic aperture radar （SAR） stereo geolocation application, the final geolocation ac- curacy is influenced by various error parameter sources. In this paper, an airborne SAR stereo geolocation parameter error model, involving the parameter errors derived from the navigation system on the flight platform, has been put forward. Moreover, a kind of near-direct method for modeling and sensitivity analysis of navigation parameter errors is also given. This method directly uses the ground reference to calculate the covariance matrix relationship between the parameter errors and the eventual geoloeation errors for ground target points. In addition, utilizing true flight track parameters＇ errors, this paper gave a verification of the method and a corresponding sensitivity analysis for airborne SAR stereo geolocation model and proved its efficiency.
基金This project is supported by Fujian Social Science Foundation of China （2003E171）.
文摘The accuracy of spatial forecasting is close relation to the selection of spatial forecasting model. Each model from special aspects using special spatial data has its own advantage or disadvantage. A more accurate spatial forecasting model can be obtained by a linear combination of some models. In this study, first-order spatial autoregressive （SAR（1）） model, Kriging algorithm interpolation （KAI） model and back-propagation neural network （BPNN） model are established by using cross-section data or time series data. A spatial linear combination forecasting （SLCF） model is obtained by the combination models mentioned above. An empirical research by these models is carried out with forecasting some areas＇ GDP per capita in Fujian, 2003. It is found that the best one is the SLCF model.
