A dedicated GPS buoy is designed for calibration and validation(Cal/Val)of satellite altimeters since 2014.In order to evaluate the accuracy of the sea surface height(SSH)measured by the GPS buoy,twelve campaigns have...A dedicated GPS buoy is designed for calibration and validation(Cal/Val)of satellite altimeters since 2014.In order to evaluate the accuracy of the sea surface height(SSH)measured by the GPS buoy,twelve campaigns have been done within China sea area between 2014 and 2021.In six of these campaigns,two static Global Navigation Satellite System stations were installed at distances of<1 km and 19 km from the buoy to assess how the baseline length influenced the derived SSH from the buoy solutions.The GPS buoy data was processed using the GAMIT/GLOBK software+TRACK module and CSRS-PPP tool to achieve the SSH.The SSH was compared with conventionally tide gauge(TG)data to evaluate the accuracy of the buoy with the standard deviation of the height element.The results showed that the difference in the standard deviation of the SSH from the buoy and the TG was less than 16 mm.The SSHs processed with different ephemeris(Ultra-Rapid,Rapid,Final)were not significantly different.When the baseline length was 19 km,the SSH solution of the GPS buoy performed well,with standard bias of less than 26 mm between the heights measured by the buoy and TG,meaning that the buoy could be used for Cal/Val of altimeters.The bias between the Canadian Spatial Reference System-precise point positioning tool and the TRACK varied a lot,and some of them were over 130 mm.This deemed too high to be useful for Cal/Val of satellite altimeters.Moreover,the GPS buoy solutions processed by GAMIT/GLOBK software+TRACK module were used for in-orbit Cal/Val of HY-2B/C satellites in ten campaigns.The SSH and significant wave height of the altimeters showed good agreements with the GPS buoy solutions.展开更多
Accurate histopathology classification is a crucial factor in the diagnosis and treatment of Cholangiocarcinoma(CCA).Hyperspectral images(HSI)provide rich spectral information than ordinary RGB images,making them more...Accurate histopathology classification is a crucial factor in the diagnosis and treatment of Cholangiocarcinoma(CCA).Hyperspectral images(HSI)provide rich spectral information than ordinary RGB images,making them more useful for medical diagnosis.The Convolutional Neural Network(CNN)is commonly employed in hyperspectral image classification due to its remarkable capacity for feature extraction and image classification.However,many existing CNN-based HSI classification methods tend to ignore the importance of image spatial context information and the interdependence between spectral channels,leading to unsatisfied classification performance.Thus,to address these issues,this paper proposes a Spatial-Spectral Joint Network(SSJN)model for hyperspectral image classification that utilizes spatial self-attention and spectral feature extraction.The SSJN model is derived from the ResNet18 network and implemented with the non-local and Coordinate Attention(CA)modules,which extract long-range dependencies on image space and enhance spatial features through the Branch Attention(BA)module to emphasize the region of interest.Furthermore,the SSJN model employs Conv-LSTM modules to extract long-range depen-dencies in the image spectral domain.This addresses the gradient disappearance/explosion phenom-ena and enhances the model classification accuracy.The experimental results show that the pro-posed SSJN model is more efficient in leveraging the spatial and spectral information of hyperspec-tral images on multidimensional microspectral datasets of CCA,leading to higher classification accuracy,and may have useful references for medical diagnosis of CCA.展开更多
Nonhuman primates are closest to humans in terms of lineage,and middle cerebral artery ischemia/reperfusion responses of nonhuman primates are most similar to ischemic stroke in humans.Therefore,nonhuman primates coul...Nonhuman primates are closest to humans in terms of lineage,and middle cerebral artery ischemia/reperfusion responses of nonhuman primates are most similar to ischemic stroke in humans.Therefore,nonhuman primates could be utilized to simulate the process of ischemic stroke in the human.Few studies,however,have reported the use of endovascular technology to establish a rhesus monkey stroke model.In the present study,seven adult,male,rhesus monkeys were selected and,following anesthesia,a microcatheter was inserted into one side of the middle cerebral artery via the femoral artery to block blood flow,thereby resulting in middle cerebral artery occlusion.After 2 hours,the microcatheter was withdrawn to restore the middle cerebral artery blood flow and to establish ischemia/reperfusion.Results from angiography and magnetic resonance angiography confirmed occlusion and reopening of the middle cerebral artery.Magnetic resonance imaging revealed the existence of ischemic brain lesions,and neurological examination showed sustained functional deficits following surgery.The rhesus monkey middle cerebral artery ischemia/reperfusion models established by microcatheter embolization had the advantage of non-craniotomy invasion and reproducibility.The scope and degree of ischemic damage using this model was controllable.Therefore,this nonhuman primate model is an ideal model for cerebral ischemia and reperfusion.展开更多
Satellite altimeter needs to be calibrated to evaluate the accuracy of sea surface height data.The dedicated altimeter calibration field needs to establish a special calibration strategy and needs to evaluate its cali...Satellite altimeter needs to be calibrated to evaluate the accuracy of sea surface height data.The dedicated altimeter calibration field needs to establish a special calibration strategy and needs to evaluate its calibration ability.This paper describes absolute calibration of HY-2 B altimeter SSH using the GPS calibration method at the newly Wanshan calibration site,located in the Wanshan Islands,China.There are two HY-2 B altimeter passes across the Wanshan calibration site.Pass No.362 is descending and the ground track passes the east of Dan’gan Island.Pass No.375 is ascending and crosses the Zhiwan Island.The GPS data processing strategy of Wanshan calibration site was established and the accuracy of GPS calibration method of Wanshan calibration site was evaluated.Meanwhile,the processing strategies of the HY-2 B altimeter for the Wanshan calibration site were established,and a dedicated geoid model data were used to benefit the calibration accuracy.The time-averaged HY-2 B altimeter bias was approximately 2.12 cm with a standard deviation of 2.08 cm.The performance of the HY-2 B correction microwave radiometer was also evaluated in terms of the wet troposphere path delay and showed a mean difference-0.2 cm with a 1.4 cm standard deviation with respect to the in situ GPS radiosonde.展开更多
Professor John Sweeney,an Associate Editor of Psychoradiology and Visiting Professor of the West China Hospital of Sichuan University,left us unexpectedly on September 10,2023,at the age of 71,shortly after a visit to...Professor John Sweeney,an Associate Editor of Psychoradiology and Visiting Professor of the West China Hospital of Sichuan University,left us unexpectedly on September 10,2023,at the age of 71,shortly after a visit to Chengdu,China,when having a reunion with his friends here.It is with great sadness that we remem-ber the extraordinary contributions of the late Professor Sweeney,who made lasting impacts in the field.展开更多
Major depressive disorder(MDD)causes great decrements in health and quality of life with increments in healthcare costs,but the causes and pathogenesis of depression remain largely unknown,which greatly prevent its ea...Major depressive disorder(MDD)causes great decrements in health and quality of life with increments in healthcare costs,but the causes and pathogenesis of depression remain largely unknown,which greatly prevent its early detection and effective treatment.With the advancement of neuroimaging approaches,numerous functional and structural alterations in the brain have been detected in MDD and more recently attempts have been made to apply these findings to clinical practice.In this review,we provide an updated summary of the progress in translational application of psychoradiological findings in MDD with a specified focus on potential clinical usage.The foreseeable clinical applications for different MRI modalities were introduced according to their role in disorder classification,subtyping,and prediction.While evidence of cerebral structural and functional changes associated with MDD classification and subtyping was heterogeneous and/or sparse,the ACC and hippocampus have been consistently suggested to be important biomarkers in predicting treatment selection and treatment response.These findings underlined the potential utility of brain biomarkers for clinical practice.展开更多
Background Cortical functional network alterations have been widely accepted as the neural basis of attention-deficit/hyperactivity disorder(ADHD).Recently,white matter has also been recognized as a novel neuroimaging...Background Cortical functional network alterations have been widely accepted as the neural basis of attention-deficit/hyperactivity disorder(ADHD).Recently,white matter has also been recognized as a novel neuroimaging marker of psychopathology and has been used as a complement to cortical functional networks to investigate brain–behavior relationships.However,disorder-specific features of white matter functional networks(WMFNs)are less well understood than those of gray matter functional networks.In the current study,we constructed WMFNs using a new strategy to characterize behavior-related network features in ADHD.Methods We recruited 46 drug-nale boys with ADHD and 46 typically developing(TD)boys,and used clustering analysis on restingstate functional magnetic resonance imaging data to generate WMFNs in each group.Intrinsic activity within each network was extracted,and the associations between network activity and behavior measures were assessed using correlation analysis.Results Nine WMFNs were identified for both ADHD and TD participants.However,boys with ADHD showed a splitting of the inferior corticospinal–cerebellar network and lacked a cognitive control network.In addition,boys with ADHD showed increased activity in the dorsal attention network and somatomotor network,which correlated positively with attention problems and hyperactivity symptom scores,respectively,while they presented decreased activity in the frontoparietal network and frontostriatal network in association with poorer performance in response inhibition,working memory,and verbal fluency.Conclusions We discovered a dual pattern of white matter network activity in drug-nale ADHD boys,with hyperactive symptom-related networks and hypoactive cognitive networks.These findings characterize two distinct types of WMFN in ADHD psychopathology.展开更多
Attention-deficit/hyperactivity disorder(ADHD)has been conceptualized as a brain dysconnectivity disorder.In the past decade,noninvasive diffusion magnetic resonance imaging(dMRI)studies have demonstrated that individ...Attention-deficit/hyperactivity disorder(ADHD)has been conceptualized as a brain dysconnectivity disorder.In the past decade,noninvasive diffusion magnetic resonance imaging(dMRI)studies have demonstrated that individuals with ADHD have alterations in the white matter structural connectome,and that these alterations are associated with core symptoms and cognitive deficits in patients.This review aims to summarize recent dMRI-based structural connectome studies in ADHD from voxel-,tractography-,and network-based perspectives.Voxel-and tractography-based studies have demonstrated disrupted microstructural properties predominantly located in the frontostriatal tracts,the corpus callosum,the corticospinal tracts,and the cingulum bundle in patients with ADHD.Network-based studies have suggested abnormal global and local efficiency as well as nodal properties in the prefrontal and parietal regions in the ADHD structural connectomes.The altered structural connectomes in those with ADHD provide significant signatures for prediction of symptoms and diagnostic classification.These studies suggest that abnormalities in the structural connectome may be one of the neural underpinnings of ADHD psychopathology and show potential for establishing imaging biomarkers in clinical evaluation.However,given that there are inconsistent findings across studies due to sample heterogeneity and analysis method variations,these ADHD-related white matter alterations are still far from informing clinical practice.Future studies with larger and more homogeneous samples are needed to validate the consistency of current results;advanced dMRI techniques can help to generatemuchmore precise estimation of whitematter pathways and assure specific fiber configurations;and finally,dimensional analysis frameworks can deepen our understanding of the neurobiology underlying ADHD.展开更多
文摘A dedicated GPS buoy is designed for calibration and validation(Cal/Val)of satellite altimeters since 2014.In order to evaluate the accuracy of the sea surface height(SSH)measured by the GPS buoy,twelve campaigns have been done within China sea area between 2014 and 2021.In six of these campaigns,two static Global Navigation Satellite System stations were installed at distances of<1 km and 19 km from the buoy to assess how the baseline length influenced the derived SSH from the buoy solutions.The GPS buoy data was processed using the GAMIT/GLOBK software+TRACK module and CSRS-PPP tool to achieve the SSH.The SSH was compared with conventionally tide gauge(TG)data to evaluate the accuracy of the buoy with the standard deviation of the height element.The results showed that the difference in the standard deviation of the SSH from the buoy and the TG was less than 16 mm.The SSHs processed with different ephemeris(Ultra-Rapid,Rapid,Final)were not significantly different.When the baseline length was 19 km,the SSH solution of the GPS buoy performed well,with standard bias of less than 26 mm between the heights measured by the buoy and TG,meaning that the buoy could be used for Cal/Val of altimeters.The bias between the Canadian Spatial Reference System-precise point positioning tool and the TRACK varied a lot,and some of them were over 130 mm.This deemed too high to be useful for Cal/Val of satellite altimeters.Moreover,the GPS buoy solutions processed by GAMIT/GLOBK software+TRACK module were used for in-orbit Cal/Val of HY-2B/C satellites in ten campaigns.The SSH and significant wave height of the altimeters showed good agreements with the GPS buoy solutions.
基金supported by National Natural Science Foundation of China(No.62101040).
文摘Accurate histopathology classification is a crucial factor in the diagnosis and treatment of Cholangiocarcinoma(CCA).Hyperspectral images(HSI)provide rich spectral information than ordinary RGB images,making them more useful for medical diagnosis.The Convolutional Neural Network(CNN)is commonly employed in hyperspectral image classification due to its remarkable capacity for feature extraction and image classification.However,many existing CNN-based HSI classification methods tend to ignore the importance of image spatial context information and the interdependence between spectral channels,leading to unsatisfied classification performance.Thus,to address these issues,this paper proposes a Spatial-Spectral Joint Network(SSJN)model for hyperspectral image classification that utilizes spatial self-attention and spectral feature extraction.The SSJN model is derived from the ResNet18 network and implemented with the non-local and Coordinate Attention(CA)modules,which extract long-range dependencies on image space and enhance spatial features through the Branch Attention(BA)module to emphasize the region of interest.Furthermore,the SSJN model employs Conv-LSTM modules to extract long-range depen-dencies in the image spectral domain.This addresses the gradient disappearance/explosion phenom-ena and enhances the model classification accuracy.The experimental results show that the pro-posed SSJN model is more efficient in leveraging the spatial and spectral information of hyperspec-tral images on multidimensional microspectral datasets of CCA,leading to higher classification accuracy,and may have useful references for medical diagnosis of CCA.
基金the National High Technology Program of China,No.2006AA02A117
文摘Nonhuman primates are closest to humans in terms of lineage,and middle cerebral artery ischemia/reperfusion responses of nonhuman primates are most similar to ischemic stroke in humans.Therefore,nonhuman primates could be utilized to simulate the process of ischemic stroke in the human.Few studies,however,have reported the use of endovascular technology to establish a rhesus monkey stroke model.In the present study,seven adult,male,rhesus monkeys were selected and,following anesthesia,a microcatheter was inserted into one side of the middle cerebral artery via the femoral artery to block blood flow,thereby resulting in middle cerebral artery occlusion.After 2 hours,the microcatheter was withdrawn to restore the middle cerebral artery blood flow and to establish ischemia/reperfusion.Results from angiography and magnetic resonance angiography confirmed occlusion and reopening of the middle cerebral artery.Magnetic resonance imaging revealed the existence of ischemic brain lesions,and neurological examination showed sustained functional deficits following surgery.The rhesus monkey middle cerebral artery ischemia/reperfusion models established by microcatheter embolization had the advantage of non-craniotomy invasion and reproducibility.The scope and degree of ischemic damage using this model was controllable.Therefore,this nonhuman primate model is an ideal model for cerebral ischemia and reperfusion.
基金The National Key R&D Program of China under contract Nos 2018YFB0504900 and 2018YFB0504904the National Natural Science Foundation of China under contract Nos 41406204 and 41501417the Operational Support Service System for Natural Resources Satellite Remote Sensing under contract No.180019。
文摘Satellite altimeter needs to be calibrated to evaluate the accuracy of sea surface height data.The dedicated altimeter calibration field needs to establish a special calibration strategy and needs to evaluate its calibration ability.This paper describes absolute calibration of HY-2 B altimeter SSH using the GPS calibration method at the newly Wanshan calibration site,located in the Wanshan Islands,China.There are two HY-2 B altimeter passes across the Wanshan calibration site.Pass No.362 is descending and the ground track passes the east of Dan’gan Island.Pass No.375 is ascending and crosses the Zhiwan Island.The GPS data processing strategy of Wanshan calibration site was established and the accuracy of GPS calibration method of Wanshan calibration site was evaluated.Meanwhile,the processing strategies of the HY-2 B altimeter for the Wanshan calibration site were established,and a dedicated geoid model data were used to benefit the calibration accuracy.The time-averaged HY-2 B altimeter bias was approximately 2.12 cm with a standard deviation of 2.08 cm.The performance of the HY-2 B correction microwave radiometer was also evaluated in terms of the wet troposphere path delay and showed a mean difference-0.2 cm with a 1.4 cm standard deviation with respect to the in situ GPS radiosonde.
文摘Professor John Sweeney,an Associate Editor of Psychoradiology and Visiting Professor of the West China Hospital of Sichuan University,left us unexpectedly on September 10,2023,at the age of 71,shortly after a visit to Chengdu,China,when having a reunion with his friends here.It is with great sadness that we remem-ber the extraordinary contributions of the late Professor Sweeney,who made lasting impacts in the field.
基金This study was supported by the National Natural Science Foundation(Nos.81171488,81671669,81621003,81820108018,and 81801681)Program for Scholars and Innovative Research Team in University(PCSIRT,No.IRT16R52)of China.
文摘Major depressive disorder(MDD)causes great decrements in health and quality of life with increments in healthcare costs,but the causes and pathogenesis of depression remain largely unknown,which greatly prevent its early detection and effective treatment.With the advancement of neuroimaging approaches,numerous functional and structural alterations in the brain have been detected in MDD and more recently attempts have been made to apply these findings to clinical practice.In this review,we provide an updated summary of the progress in translational application of psychoradiological findings in MDD with a specified focus on potential clinical usage.The foreseeable clinical applications for different MRI modalities were introduced according to their role in disorder classification,subtyping,and prediction.While evidence of cerebral structural and functional changes associated with MDD classification and subtyping was heterogeneous and/or sparse,the ACC and hippocampus have been consistently suggested to be important biomarkers in predicting treatment selection and treatment response.These findings underlined the potential utility of brain biomarkers for clinical practice.
基金The study was supported by the 1.3.5 Project for Disciplines of Excellence,West China Hospital of Sichuan University,China(grant no.ZYJC21041)the Clinical and Translational Research Fund of Chinese Academy of Medical Sciences(grant no.2021-I2MC&TB-097)the Science and Technology Project of Chengdu City,China(grant no.2019-YF05-00509-SN).
文摘Background Cortical functional network alterations have been widely accepted as the neural basis of attention-deficit/hyperactivity disorder(ADHD).Recently,white matter has also been recognized as a novel neuroimaging marker of psychopathology and has been used as a complement to cortical functional networks to investigate brain–behavior relationships.However,disorder-specific features of white matter functional networks(WMFNs)are less well understood than those of gray matter functional networks.In the current study,we constructed WMFNs using a new strategy to characterize behavior-related network features in ADHD.Methods We recruited 46 drug-nale boys with ADHD and 46 typically developing(TD)boys,and used clustering analysis on restingstate functional magnetic resonance imaging data to generate WMFNs in each group.Intrinsic activity within each network was extracted,and the associations between network activity and behavior measures were assessed using correlation analysis.Results Nine WMFNs were identified for both ADHD and TD participants.However,boys with ADHD showed a splitting of the inferior corticospinal–cerebellar network and lacked a cognitive control network.In addition,boys with ADHD showed increased activity in the dorsal attention network and somatomotor network,which correlated positively with attention problems and hyperactivity symptom scores,respectively,while they presented decreased activity in the frontoparietal network and frontostriatal network in association with poorer performance in response inhibition,working memory,and verbal fluency.Conclusions We discovered a dual pattern of white matter network activity in drug-nale ADHD boys,with hyperactive symptom-related networks and hypoactive cognitive networks.These findings characterize two distinct types of WMFN in ADHD psychopathology.
基金supported by the National Natural Science Foundation of China(Nos.82021004,81620108016,31221003)Changjiang Scholar Professorship Award(No.T2015027).
文摘Attention-deficit/hyperactivity disorder(ADHD)has been conceptualized as a brain dysconnectivity disorder.In the past decade,noninvasive diffusion magnetic resonance imaging(dMRI)studies have demonstrated that individuals with ADHD have alterations in the white matter structural connectome,and that these alterations are associated with core symptoms and cognitive deficits in patients.This review aims to summarize recent dMRI-based structural connectome studies in ADHD from voxel-,tractography-,and network-based perspectives.Voxel-and tractography-based studies have demonstrated disrupted microstructural properties predominantly located in the frontostriatal tracts,the corpus callosum,the corticospinal tracts,and the cingulum bundle in patients with ADHD.Network-based studies have suggested abnormal global and local efficiency as well as nodal properties in the prefrontal and parietal regions in the ADHD structural connectomes.The altered structural connectomes in those with ADHD provide significant signatures for prediction of symptoms and diagnostic classification.These studies suggest that abnormalities in the structural connectome may be one of the neural underpinnings of ADHD psychopathology and show potential for establishing imaging biomarkers in clinical evaluation.However,given that there are inconsistent findings across studies due to sample heterogeneity and analysis method variations,these ADHD-related white matter alterations are still far from informing clinical practice.Future studies with larger and more homogeneous samples are needed to validate the consistency of current results;advanced dMRI techniques can help to generatemuchmore precise estimation of whitematter pathways and assure specific fiber configurations;and finally,dimensional analysis frameworks can deepen our understanding of the neurobiology underlying ADHD.
