Characterization of vegetation effect on soil response is essential for comprehending site-specific hydrological processes.Traditional research often relies on sensors or remote sensing data to examine the hydrologica...Characterization of vegetation effect on soil response is essential for comprehending site-specific hydrological processes.Traditional research often relies on sensors or remote sensing data to examine the hydrological properties of vegetation zones,yet these methods are limited by either measurement sparsity or spatial inaccuracy.Therefore,this paper is the first to propose a data-driven approach that incorporates high-temporal-resolution electrical resistivity tomography(ERT)to quantify soil hydrological response.Time-lapse ERT is deployed on a vegetated slope site in Foshan,China,during a discontinuous rainfall induced by Typhoon Haikui.A total of 97 ERT measurements were collected with an average time interval of 2.7 hours.The Gaussian Mixture Model(GMM)is applied to quantify the level of response and objectively classify impact zones based on features extracted directly from the ERT data.The resistivity-moisture content correlation is established based on on-site sensor data to characterize infiltration and evapotranspiration across wet-dry conditions.The findings are compared with the Normalized Difference Vegetation Index(NDVI),a common indicator for vegetation quantification,to reveal potential spatial errors in remote sensing data.In addition,this study provides discussions on the potential applications and future directions.This paper showcases significant spatio-temporal advantages over existing studies,providing a more detailed and accurate characterization of superficial soil hydrological response.展开更多
Fourier series analysis is proposed as a new technique to address the problem of“sub-pixel motion”in deriving cloud motion winds(CMW)from high temporal resolution images.Based on a concept different from that of max...Fourier series analysis is proposed as a new technique to address the problem of“sub-pixel motion”in deriving cloud motion winds(CMW)from high temporal resolution images.Based on a concept different from that of maximum correlation matching technique,the Fourier technique computes phase speed as an estimate of cloud motion.It is very effective for tracking small cellular clouds in 1-min interval images and more efficient for computation than the maximum correlation technique because only two templates in same size are involved in primary tracking procedure. Moreover it obtains not only CMW vectors but potentially also velocity spectrum and variance.A practical example is given to show the cloud motion winds from 1-min interval images with the Fourier method versus those from traditional 30-min interval images with maximum correlation technique.Problems that require further investigation before the Fourier technique can be regarded as a viable technique,especially for cloud tracking with high temporal resolution images,are also revealed.展开更多
Super-resolution(SR)microscopy has dramatically enhanced our understanding of biological processes.However,scattering media in thick specimens severely limits the spatial resolution,often rendering the images unclear ...Super-resolution(SR)microscopy has dramatically enhanced our understanding of biological processes.However,scattering media in thick specimens severely limits the spatial resolution,often rendering the images unclear or indistinguishable.Additionally,live-cell imaging faces challenges in achieving high temporal resolution for fast-moving subcellular structures.Here,we present the principles of a synthetic wave microscopy(SWM)to extract three-dimensional information from thick unlabeled specimens,where photobleaching and phototoxicity are avoided.SWM exploits multiple-wave interferometry to reveal the specimen’s phase information in the area of interest,which is not affected by the scattering media in the optical path.SWM achieves~0.42λ/NA resolution at an imaging speed of up to 106 pixels/s.SWM proves better temporal resolution and sensitivity than the most conventional microscopes currently available while maintaining exceptional SR and anti-scattering capabilities.Penetrating through the scattering media is challenging for conventional imaging techniques.Remarkably,SWM retains its efficacy even in conditions of low signal-to-noise ratios.It facilitates the visualization of dynamic subcellular structures in live cells,encompassing tubular endoplasmic reticulum(ER),lipid droplets,mitochondria,and lysosomes.展开更多
Framing photography provides a high temporal resolution and minimizes crosstalk between adjacent frames,making it an indispensable tool for recording ultrafast phenomena.To date,various ultrafast framing photography t...Framing photography provides a high temporal resolution and minimizes crosstalk between adjacent frames,making it an indispensable tool for recording ultrafast phenomena.To date,various ultrafast framing photography techniques have been developed.However,simultaneously achieving large sequence depth,high image quality,ultrashort exposure time,and flexible frame interval remains a significant challenge.Herein,we present a spatiotemporal shearing-based ultrafast framing photography,termed STS-UFP,designed to address this challenge.STS-UFP employs an adjustable ultrashort laser pulse train with a spectrum shuttle to illuminate the dynamic scenes for extracting the transient information and records discrete frames using a streak camera via spatiotemporal shearing.Based on its unique design,STS-UFP achieves high-quality ultrafast imaging with a sequence depth of up to 16 frames and frame intervals ranging from hundreds of picoseconds to nanoseconds,while maintaining an extremely short(picosecond)exposure time.The exceptional performance of STS-UFP is demonstrated through experimental observations of femtosecond laser-induced plasma and shockwave in water,femtosecond laser ablation in biological tissue,and femtosecond laser-induced shockwave on a silicon surface.Given its remarkable imaging capabilities,STS-UFP serves as a powerful tool for precisely observing ultrafast dynamics and holds significant potential for advancing studies of ultrafast phenomena.展开更多
Taking advantage of the stochastic photoswitching of genetically encodable reversibly photoswitchable fluorescent proteins(RSFPs),super-resolution optical fluctuation imaging(SOFI)and its variant photochromic stochast...Taking advantage of the stochastic photoswitching of genetically encodable reversibly photoswitchable fluorescent proteins(RSFPs),super-resolution optical fluctuation imaging(SOFI)and its variant photochromic stochastic optical fluctuation imaging(pcSOFI)are valuable tools for wide field super-resolution(SR)imaging.Live-cell(pc)SOFI,which requires a small number of original frames to reconstruct an SR image,is prone to structural discontinuity artifacts and low spatial resolution.Herein,we developed a repeated synchronized on-and gradually off-switching SOFI(SOGO-SOFI)that maximized the photoswitching frequency of RSFPs by light modulation and required only 20 frames for high-quality reconstruction.Live-cell SOGO-SOFI imaging of the endoplasmic reticulum(ER)exhibited 10 times higher temporal resolution(100 fps)and fewer artifacts than pcSOFI.Moreover,a combination of SOGO-SOFI with Airyscan further increased the image contrast and the resolution of Airyscan by a factor of 1.5 from 140 nm to 91 nm.The capabilities of SOGO-SOFI were further demonstrated by dual-color imaging of nucleolar proteins in mammalian cells and deep imaging of ER structures in thick brain slices(20.6µm).展开更多
While data like HJ-1 CCD images have advantageous spatial characteristics for describing crop properties,the temporal resolution of the data is rather low,which can be easily made worse by cloud contamination.In contr...While data like HJ-1 CCD images have advantageous spatial characteristics for describing crop properties,the temporal resolution of the data is rather low,which can be easily made worse by cloud contamination.In contrast,although Moderate Resolution Imaging Spectroradiometer(MODIS)can only achieve a spatial resolution of 250 m in its normalised difference vegetation index(NDVI)product,it has a high temporal resolution,covering the Earth up to multiple times per day.To combine the high spatial resolution and high temporal resolution of different data sources,a new method(Spatial and Temporal Adaptive Vegetation index Fusion Model[STAVFM])for blending NDVI of different spatial and temporal resolutions to produce high spatialtemporal resolution NDVI datasets was developed based on Spatial and Temporal Adaptive Reflectance Fusion Model(STARFM).STAVFM defines a time window according to the temporal variation of crops,takes crop phenophase into consideration and improves the temporal weighting algorithm.The result showed that the new method can combine the temporal information of MODIS NDVI and spatial difference information of HJ-1 CCD NDVI to generate an NDVI dataset with both high spatial and high temporal resolution.An application of the generated NDVI dataset in crop biomass estimation was provided.An average absolute error of 17.2%was achieved.The estimated winter wheat biomass correlated well with observed biomass(R^(2) of 0.876).We conclude that the new dataset will improve the application of crop biomass estimation by describing the crop biomass accumulation in detail.There is potential to apply the approach in many other studies,including crop production estimation,crop growth monitoring and agricultural ecosystem carbon cycle research,which will contribute to the implementation of Digital Earth by describing land surface processes in detail.展开更多
High spatial resolution and high temporal frequency fractional vegetation cover(FVC) products have been increasingly in demand to monitor and research land surface processes. This paper develops an algorithm to estima...High spatial resolution and high temporal frequency fractional vegetation cover(FVC) products have been increasingly in demand to monitor and research land surface processes. This paper develops an algorithm to estimate FVC at a 30-m/15-day resolution over China by taking advantage of the spatial and temporal information from different types of sensors: the 30-m resolution sensor on the Chinese environment satellite(HJ-1) and the 1-km Moderate Resolution Imaging Spectroradiometer(MODIS). The algorithm was implemented for each main vegetation class and each land cover type over China. First, the high spatial resolution and high temporal frequency normalized difference vegetation index(NDVI) was acquired by using the continuous correction(CC) data assimilation method. Then, FVC was generated with a nonlinear pixel unmixing model. Model coefficients were obtained by statistical analysis of the MODIS NDVI. The proposed method was evaluated based on in situ FVC measurements and a global FVC product(GEOV1 FVC). Direct validation using in situ measurements at 97 sampling plots per half month in 2010 showed that the annual mean errors(MEs) of forest, cropland, and grassland were-0.025, 0.133, and 0.160, respectively, indicating that the FVCs derived from the proposed algorithm were consistent with ground measurements [R2 = 0.809,root-mean-square deviation(RMSD) = 0.065]. An intercomparison between the proposed FVC and GEOV1 FVC demonstrated that the two products had good spatial–temporal consistency and similar magnitude(RMSD approximates 0.1). Overall, the approach provides a new operational way to estimate high spatial resolution and high temporal frequency FVC from multiple remote sensing datasets.展开更多
In monitoring and predicting high-impact weather(HIW)events,targeted atmospheric temperature and moisture sounding observations in sensitive areas are more valuable than conventional observations.The conditional nonli...In monitoring and predicting high-impact weather(HIW)events,targeted atmospheric temperature and moisture sounding observations in sensitive areas are more valuable than conventional observations.The conditional nonlinear optimal perturbation(CNOP)method and the linear singular vector(SV)method can be employed to identify these weather-sensitive areas for targeted observations.Such observations can be conducted by using hyperspectral infrared sounders onboard geostationary weather satellites.The Geostationary Interferometric Infrared Sounder(GIIRS)onboard China's Fengyun(FY)-4geostationary satellite series can provide atmospheric sounding observations with a temporal resolution of up to 15 min over areas prone to active weather events.GIIRS offers unprecedented opportunities for targeted observations,enabling flexible measurement modes that focus on weather-sensitive areas.High-temporal-resolution measurements not only reveal the threedimensional(3D)thermodynamic structure of the atmosphere,but also track moisture characteristics to capture the 3D dynamic structure.Moreover,high-temporal-resolution measurements of clear radiances can enhance atmospheric sounding retrievals(used for HIW situation awareness)and data assimilation(used to improve numerical weather prediction).The four-dimensional variational(4D-Var)system facilitates the utilization of the high-temporal-resolution GIIRS targeted observations.In this study,we explore the applications of FY-4A and FY-4B GIIRS targeted observations and focus on data assimilation based on the 4DVar system for improving HIW forecasts.Several typhoon cases are selected for impact analysis.Moreover,we compare CNOP and SV methods for identifying sensitive areas,and use the 4D-Var assimilation system of the Global Assimilation Forecasting System of the China Meteorological Administration(CMA-GFS)for real-time data assimilation.The results indicate hightemporal-resolution observations positively impact typhoon forecasts,with higher temporal resolution yielding greater benefits.This highlights the substantial value of FY-4 GIIRS targeted observations in forecasting HIW events.展开更多
Real time rainfall events monitoring is very important for a large number of reasons: Civil Protection, hydrogeological risk management, hydroelectric power purposes, road and traffic regulation, and tourism. Efficien...Real time rainfall events monitoring is very important for a large number of reasons: Civil Protection, hydrogeological risk management, hydroelectric power purposes, road and traffic regulation, and tourism. Efficient monitoring operations need continuous, high-resolution and large-coverage data. To monitor and observe extreme rainfall events, often much localized over small basins of interest, and that could frequently causing flash floods, an unrealistic extremely dense rain gauge network should be needed. On the other hand, common large C-band or S-band long range radars do not provide the necessary spatial and temporal resolution. Simple short-range X-band mini weather radar can be a valid compromise solution. The present work shows how a single polarization, non-Doppler and non-coherent, simple and low cost X-band radar allowed monitoring three very intense rainfall events occurred near Turin during July 2014. The events, which caused damages and floods, are detected and monitored in real time with a sample rate of 1 minute and a radial spatial resolution of 60 m, thus allowing to describe the intensity of the precipitation on each small portion of territory. This information could be very useful if used by authorities in charge of Civil Protection in order to avoid inconvenience to people and to monitor dangerous situations.展开更多
Objective:To evaluate the significance of Eustachian tube(ET)angles and ET pretympanic diameter on high resolution computed tomography(HRCT)Temporal bone in patients with chronic otitis media(COM).Methods:A retrospect...Objective:To evaluate the significance of Eustachian tube(ET)angles and ET pretympanic diameter on high resolution computed tomography(HRCT)Temporal bone in patients with chronic otitis media(COM).Methods:A retrospective study was carried out at Tertiary care centre.Group A included 92 ears with COM(38 patients with bilateral COM and 16 with unilateral COM);and Group B included 108 normal ears(54 patients with bilateral normal ears).Reid plane-ET angle,Tubotympanic angle and the ET pretympanic diameter was evaluated by HRCT temporal bone,and compared in the two groups.Patients with chronic otitis media(Group A)were subdivided into Group A1(Blocked ET)and Group A2(Patent ET).The parameters were evaluated and compared in the subgroups too.Results:The mean Reid plane-ET angle and Tubotympanic angle in Group A was 25.412.57 and 148.123.43 respectively;whereas in Group B it was 27.563.62 and 145.144.34 respectively.Reid plane-ET angle was significantly less in patients with COM and Tubotympanic angle was significantly more obtuse in COM patients.ET pretympanic diameter was(5.372.10)mm in Group A and(6.472.40)mm in Group B.It was significantly less in patients with COM.A significant correlation was found between the ET patency and the two ET parameters(Reid plane-ET angle and pretympanic diameter).Conclusions:Eustachian tube angles in adults may play a significant role in the etiology of chronic otitis media.Decrease in Reid plane-ET angle and pretympanic diameter on HRCT temporal bone can be used to predict ET dysfunction and to plan the surgical management of chronic otitis media.展开更多
Age-related macular degeneration is the leading cause of irreversible visual impairment in the elderly.It manifests in two forms,wet and dry.However,the mechanisms underlying spontaneous dry age-related macular degene...Age-related macular degeneration is the leading cause of irreversible visual impairment in the elderly.It manifests in two forms,wet and dry.However,the mechanisms underlying spontaneous dry age-related macular degeneration(SD-AMD)remain unclear.Herein,we constructed a single-cell retinal transcription atlas in aged non-human primates with SD-AMD.Retinal tissues affected by SD-AMD exhibited a more degenerative and dysfunctional transcriptomic landscape,with global activation of the oxidative stress response and apoptotic signaling pathway.We found two distinct Müller glia subtypes in normal aged and SD-AMD macaques,one exhibiting a photoreceptor-like transcriptome and the other exhibiting a typical Müller glia transcriptome.As SD-AMD progressed,the proportion of photoreceptor-like Müller glial cells decreased,and photoreceptor-function-associated genes were downregulated,indicating weaker Müller glia potential to transit into photoreceptor-like functional states.Microglial cells showed activated features,and the complement system was activated during disease pathogenesis.We also found that the disruption of iron homeostasis and ferroptosis could promote SD-AMD pathogenesis in neural cells.Further experimentation revealed that a ferroptosis inhibitor exerted a profound rescuing effect in SD-AMD mouse models.Based on these results,our study introduces a path toward understanding the pathogenesis of SD-AMD in a non-human primate model at single-cell resolution.展开更多
基金support from the National Key R&D Program of China(2021YFC3001003)Guangdong Provincial Department of Science and Technology(2022A0505030019)Science and Technology Development Fund,Macao SAR(File nos.0056/2023/RIB2,001/2024/SKL).
文摘Characterization of vegetation effect on soil response is essential for comprehending site-specific hydrological processes.Traditional research often relies on sensors or remote sensing data to examine the hydrological properties of vegetation zones,yet these methods are limited by either measurement sparsity or spatial inaccuracy.Therefore,this paper is the first to propose a data-driven approach that incorporates high-temporal-resolution electrical resistivity tomography(ERT)to quantify soil hydrological response.Time-lapse ERT is deployed on a vegetated slope site in Foshan,China,during a discontinuous rainfall induced by Typhoon Haikui.A total of 97 ERT measurements were collected with an average time interval of 2.7 hours.The Gaussian Mixture Model(GMM)is applied to quantify the level of response and objectively classify impact zones based on features extracted directly from the ERT data.The resistivity-moisture content correlation is established based on on-site sensor data to characterize infiltration and evapotranspiration across wet-dry conditions.The findings are compared with the Normalized Difference Vegetation Index(NDVI),a common indicator for vegetation quantification,to reveal potential spatial errors in remote sensing data.In addition,this study provides discussions on the potential applications and future directions.This paper showcases significant spatio-temporal advantages over existing studies,providing a more detailed and accurate characterization of superficial soil hydrological response.
基金This study was partly supported by the National Basic Research of China:Project G1998040907.
文摘Fourier series analysis is proposed as a new technique to address the problem of“sub-pixel motion”in deriving cloud motion winds(CMW)from high temporal resolution images.Based on a concept different from that of maximum correlation matching technique,the Fourier technique computes phase speed as an estimate of cloud motion.It is very effective for tracking small cellular clouds in 1-min interval images and more efficient for computation than the maximum correlation technique because only two templates in same size are involved in primary tracking procedure. Moreover it obtains not only CMW vectors but potentially also velocity spectrum and variance.A practical example is given to show the cloud motion winds from 1-min interval images with the Fourier method versus those from traditional 30-min interval images with maximum correlation technique.Problems that require further investigation before the Fourier technique can be regarded as a viable technique,especially for cloud tracking with high temporal resolution images,are also revealed.
基金support from CAS West Light Grant (xbzgzdsys-202206)National Key Research and Development Program of China (2021YFA1401003).
文摘Super-resolution(SR)microscopy has dramatically enhanced our understanding of biological processes.However,scattering media in thick specimens severely limits the spatial resolution,often rendering the images unclear or indistinguishable.Additionally,live-cell imaging faces challenges in achieving high temporal resolution for fast-moving subcellular structures.Here,we present the principles of a synthetic wave microscopy(SWM)to extract three-dimensional information from thick unlabeled specimens,where photobleaching and phototoxicity are avoided.SWM exploits multiple-wave interferometry to reveal the specimen’s phase information in the area of interest,which is not affected by the scattering media in the optical path.SWM achieves~0.42λ/NA resolution at an imaging speed of up to 106 pixels/s.SWM proves better temporal resolution and sensitivity than the most conventional microscopes currently available while maintaining exceptional SR and anti-scattering capabilities.Penetrating through the scattering media is challenging for conventional imaging techniques.Remarkably,SWM retains its efficacy even in conditions of low signal-to-noise ratios.It facilitates the visualization of dynamic subcellular structures in live cells,encompassing tubular endoplasmic reticulum(ER),lipid droplets,mitochondria,and lysosomes.
基金National Natural Science Foundation of China(12325408,12274129,12274139,12374274,62175066,92150102,12474404,12304338,12471368,62475070)Fundamental Research Funds for the Central Universities。
文摘Framing photography provides a high temporal resolution and minimizes crosstalk between adjacent frames,making it an indispensable tool for recording ultrafast phenomena.To date,various ultrafast framing photography techniques have been developed.However,simultaneously achieving large sequence depth,high image quality,ultrashort exposure time,and flexible frame interval remains a significant challenge.Herein,we present a spatiotemporal shearing-based ultrafast framing photography,termed STS-UFP,designed to address this challenge.STS-UFP employs an adjustable ultrashort laser pulse train with a spectrum shuttle to illuminate the dynamic scenes for extracting the transient information and records discrete frames using a streak camera via spatiotemporal shearing.Based on its unique design,STS-UFP achieves high-quality ultrafast imaging with a sequence depth of up to 16 frames and frame intervals ranging from hundreds of picoseconds to nanoseconds,while maintaining an extremely short(picosecond)exposure time.The exceptional performance of STS-UFP is demonstrated through experimental observations of femtosecond laser-induced plasma and shockwave in water,femtosecond laser ablation in biological tissue,and femtosecond laser-induced shockwave on a silicon surface.Given its remarkable imaging capabilities,STS-UFP serves as a powerful tool for precisely observing ultrafast dynamics and holds significant potential for advancing studies of ultrafast phenomena.
基金support for the LSM980 microscopy operationfunded by the National Key Research and Development Program of China(2017YFA0505300)+1 种基金the Natural Science Foundation of China(21927813,32027901,21778069,31870857)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB37040301).
文摘Taking advantage of the stochastic photoswitching of genetically encodable reversibly photoswitchable fluorescent proteins(RSFPs),super-resolution optical fluctuation imaging(SOFI)and its variant photochromic stochastic optical fluctuation imaging(pcSOFI)are valuable tools for wide field super-resolution(SR)imaging.Live-cell(pc)SOFI,which requires a small number of original frames to reconstruct an SR image,is prone to structural discontinuity artifacts and low spatial resolution.Herein,we developed a repeated synchronized on-and gradually off-switching SOFI(SOGO-SOFI)that maximized the photoswitching frequency of RSFPs by light modulation and required only 20 frames for high-quality reconstruction.Live-cell SOGO-SOFI imaging of the endoplasmic reticulum(ER)exhibited 10 times higher temporal resolution(100 fps)and fewer artifacts than pcSOFI.Moreover,a combination of SOGO-SOFI with Airyscan further increased the image contrast and the resolution of Airyscan by a factor of 1.5 from 140 nm to 91 nm.The capabilities of SOGO-SOFI were further demonstrated by dual-color imaging of nucleolar proteins in mammalian cells and deep imaging of ER structures in thick brain slices(20.6µm).
基金The research was supported by National Natural Science Foundation of China,Nos.40801144 and 41171331Knowledge Innovation Program of CAS,No.KSCX1-YW-09-01the National Key Technology R&D Program,No.2008BADA8B02.
文摘While data like HJ-1 CCD images have advantageous spatial characteristics for describing crop properties,the temporal resolution of the data is rather low,which can be easily made worse by cloud contamination.In contrast,although Moderate Resolution Imaging Spectroradiometer(MODIS)can only achieve a spatial resolution of 250 m in its normalised difference vegetation index(NDVI)product,it has a high temporal resolution,covering the Earth up to multiple times per day.To combine the high spatial resolution and high temporal resolution of different data sources,a new method(Spatial and Temporal Adaptive Vegetation index Fusion Model[STAVFM])for blending NDVI of different spatial and temporal resolutions to produce high spatialtemporal resolution NDVI datasets was developed based on Spatial and Temporal Adaptive Reflectance Fusion Model(STARFM).STAVFM defines a time window according to the temporal variation of crops,takes crop phenophase into consideration and improves the temporal weighting algorithm.The result showed that the new method can combine the temporal information of MODIS NDVI and spatial difference information of HJ-1 CCD NDVI to generate an NDVI dataset with both high spatial and high temporal resolution.An application of the generated NDVI dataset in crop biomass estimation was provided.An average absolute error of 17.2%was achieved.The estimated winter wheat biomass correlated well with observed biomass(R^(2) of 0.876).We conclude that the new dataset will improve the application of crop biomass estimation by describing the crop biomass accumulation in detail.There is potential to apply the approach in many other studies,including crop production estimation,crop growth monitoring and agricultural ecosystem carbon cycle research,which will contribute to the implementation of Digital Earth by describing land surface processes in detail.
基金Supported by the National Key Research and Development Program of China (2018YFC1506501, 2018YFA0605503, and2016YFB0501502)Special Program of Gaofen Satellites (04-Y30B01-9001-18/20-3-1)National Natural Science Foundation of China (41871230 and 41871231)。
文摘High spatial resolution and high temporal frequency fractional vegetation cover(FVC) products have been increasingly in demand to monitor and research land surface processes. This paper develops an algorithm to estimate FVC at a 30-m/15-day resolution over China by taking advantage of the spatial and temporal information from different types of sensors: the 30-m resolution sensor on the Chinese environment satellite(HJ-1) and the 1-km Moderate Resolution Imaging Spectroradiometer(MODIS). The algorithm was implemented for each main vegetation class and each land cover type over China. First, the high spatial resolution and high temporal frequency normalized difference vegetation index(NDVI) was acquired by using the continuous correction(CC) data assimilation method. Then, FVC was generated with a nonlinear pixel unmixing model. Model coefficients were obtained by statistical analysis of the MODIS NDVI. The proposed method was evaluated based on in situ FVC measurements and a global FVC product(GEOV1 FVC). Direct validation using in situ measurements at 97 sampling plots per half month in 2010 showed that the annual mean errors(MEs) of forest, cropland, and grassland were-0.025, 0.133, and 0.160, respectively, indicating that the FVCs derived from the proposed algorithm were consistent with ground measurements [R2 = 0.809,root-mean-square deviation(RMSD) = 0.065]. An intercomparison between the proposed FVC and GEOV1 FVC demonstrated that the two products had good spatial–temporal consistency and similar magnitude(RMSD approximates 0.1). Overall, the approach provides a new operational way to estimate high spatial resolution and high temporal frequency FVC from multiple remote sensing datasets.
基金supported by the National Natural Science Foundation of China(Grant Nos.42075155,42205158)the China Meteorological Administration Fengyun Application Pioneering Project(Grant No.FY-APP-2021.0204)。
文摘In monitoring and predicting high-impact weather(HIW)events,targeted atmospheric temperature and moisture sounding observations in sensitive areas are more valuable than conventional observations.The conditional nonlinear optimal perturbation(CNOP)method and the linear singular vector(SV)method can be employed to identify these weather-sensitive areas for targeted observations.Such observations can be conducted by using hyperspectral infrared sounders onboard geostationary weather satellites.The Geostationary Interferometric Infrared Sounder(GIIRS)onboard China's Fengyun(FY)-4geostationary satellite series can provide atmospheric sounding observations with a temporal resolution of up to 15 min over areas prone to active weather events.GIIRS offers unprecedented opportunities for targeted observations,enabling flexible measurement modes that focus on weather-sensitive areas.High-temporal-resolution measurements not only reveal the threedimensional(3D)thermodynamic structure of the atmosphere,but also track moisture characteristics to capture the 3D dynamic structure.Moreover,high-temporal-resolution measurements of clear radiances can enhance atmospheric sounding retrievals(used for HIW situation awareness)and data assimilation(used to improve numerical weather prediction).The four-dimensional variational(4D-Var)system facilitates the utilization of the high-temporal-resolution GIIRS targeted observations.In this study,we explore the applications of FY-4A and FY-4B GIIRS targeted observations and focus on data assimilation based on the 4DVar system for improving HIW forecasts.Several typhoon cases are selected for impact analysis.Moreover,we compare CNOP and SV methods for identifying sensitive areas,and use the 4D-Var assimilation system of the Global Assimilation Forecasting System of the China Meteorological Administration(CMA-GFS)for real-time data assimilation.The results indicate hightemporal-resolution observations positively impact typhoon forecasts,with higher temporal resolution yielding greater benefits.This highlights the substantial value of FY-4 GIIRS targeted observations in forecasting HIW events.
文摘Real time rainfall events monitoring is very important for a large number of reasons: Civil Protection, hydrogeological risk management, hydroelectric power purposes, road and traffic regulation, and tourism. Efficient monitoring operations need continuous, high-resolution and large-coverage data. To monitor and observe extreme rainfall events, often much localized over small basins of interest, and that could frequently causing flash floods, an unrealistic extremely dense rain gauge network should be needed. On the other hand, common large C-band or S-band long range radars do not provide the necessary spatial and temporal resolution. Simple short-range X-band mini weather radar can be a valid compromise solution. The present work shows how a single polarization, non-Doppler and non-coherent, simple and low cost X-band radar allowed monitoring three very intense rainfall events occurred near Turin during July 2014. The events, which caused damages and floods, are detected and monitored in real time with a sample rate of 1 minute and a radial spatial resolution of 60 m, thus allowing to describe the intensity of the precipitation on each small portion of territory. This information could be very useful if used by authorities in charge of Civil Protection in order to avoid inconvenience to people and to monitor dangerous situations.
文摘Objective:To evaluate the significance of Eustachian tube(ET)angles and ET pretympanic diameter on high resolution computed tomography(HRCT)Temporal bone in patients with chronic otitis media(COM).Methods:A retrospective study was carried out at Tertiary care centre.Group A included 92 ears with COM(38 patients with bilateral COM and 16 with unilateral COM);and Group B included 108 normal ears(54 patients with bilateral normal ears).Reid plane-ET angle,Tubotympanic angle and the ET pretympanic diameter was evaluated by HRCT temporal bone,and compared in the two groups.Patients with chronic otitis media(Group A)were subdivided into Group A1(Blocked ET)and Group A2(Patent ET).The parameters were evaluated and compared in the subgroups too.Results:The mean Reid plane-ET angle and Tubotympanic angle in Group A was 25.412.57 and 148.123.43 respectively;whereas in Group B it was 27.563.62 and 145.144.34 respectively.Reid plane-ET angle was significantly less in patients with COM and Tubotympanic angle was significantly more obtuse in COM patients.ET pretympanic diameter was(5.372.10)mm in Group A and(6.472.40)mm in Group B.It was significantly less in patients with COM.A significant correlation was found between the ET patency and the two ET parameters(Reid plane-ET angle and pretympanic diameter).Conclusions:Eustachian tube angles in adults may play a significant role in the etiology of chronic otitis media.Decrease in Reid plane-ET angle and pretympanic diameter on HRCT temporal bone can be used to predict ET dysfunction and to plan the surgical management of chronic otitis media.
基金supported by the National Key Research and Development Program of China(2017YFA0105804 and 2020YFA0112701).
文摘Age-related macular degeneration is the leading cause of irreversible visual impairment in the elderly.It manifests in two forms,wet and dry.However,the mechanisms underlying spontaneous dry age-related macular degeneration(SD-AMD)remain unclear.Herein,we constructed a single-cell retinal transcription atlas in aged non-human primates with SD-AMD.Retinal tissues affected by SD-AMD exhibited a more degenerative and dysfunctional transcriptomic landscape,with global activation of the oxidative stress response and apoptotic signaling pathway.We found two distinct Müller glia subtypes in normal aged and SD-AMD macaques,one exhibiting a photoreceptor-like transcriptome and the other exhibiting a typical Müller glia transcriptome.As SD-AMD progressed,the proportion of photoreceptor-like Müller glial cells decreased,and photoreceptor-function-associated genes were downregulated,indicating weaker Müller glia potential to transit into photoreceptor-like functional states.Microglial cells showed activated features,and the complement system was activated during disease pathogenesis.We also found that the disruption of iron homeostasis and ferroptosis could promote SD-AMD pathogenesis in neural cells.Further experimentation revealed that a ferroptosis inhibitor exerted a profound rescuing effect in SD-AMD mouse models.Based on these results,our study introduces a path toward understanding the pathogenesis of SD-AMD in a non-human primate model at single-cell resolution.
