Objective To determine the association between the irregularity of carotid plaque surface using multidimensional magnetic resonance imaging(MRI) of ipsilateral acute cerebral infarction(ACI) cases. Methods Patients wi...Objective To determine the association between the irregularity of carotid plaque surface using multidimensional magnetic resonance imaging(MRI) of ipsilateral acute cerebral infarction(ACI) cases. Methods Patients with recent cerebrovascular symptoms(stroke or transient ischemic attack < 2 weeks) and atherosclerotic plaque in at least one carotid artery were diagnosed by B-mode ultrasound imaging(intima-media thickness ≥ 1.5 mm) and recruited for the present study. Irregular surface was defined when plaque surface was uneven with high and low fluctuation or plaque with surface ulceration. The irregularity of carotid plaque surface was determined on axial or oblique images alone(single-dimension) and on both axial images and oblique images(multidimensions), separately. Univariate and multivariate logistic regression analyses were performed to calculate the odds ratio(OR) and the corresponding 95% CI of the irregular plaque surface in discriminating the presence of ipsilateral ACI. Results A total of 217 included subjects(mean age: 60.7 ± 10.2 years, 149 men) were recruited and 89(41.0%), 88(40.6%) and 118(54.4%) of them exhibited irregular plaque surface on axial, oblique and multidimensional MR images, respectively. The OR of irregularity of the plaque surface was determined by multidimensional MRI to be 5.88(95% CI: 3.16–10.96, P < 0.001) in discriminating the presence of ipsilateral ACI. Following adjustment for clinical confounding factors, this association remained statistically significant(OR = 5.65, 95% CI: 2.53–12.60, P < 0.001). The analysis included further adjustment for the presence of lipid-rich necrotic core, intraplaque hemorrhage and stenosis and the results included that this association also remained statistically significant(OR = 6.08, 95% CI: 2.52–14.68, P < 0.001). Conclusions The irregular plaque surface was determined by multidimensional MRI as an independent indicator for ipsilateral acute cerebral infarction.展开更多
Localized surface plasmon resonance(LSPR)can be supported by metallic nanoparticles and engineered nanostructures.An understanding of the spatially resolved near-field properties and dynamics of LSPR is important,but ...Localized surface plasmon resonance(LSPR)can be supported by metallic nanoparticles and engineered nanostructures.An understanding of the spatially resolved near-field properties and dynamics of LSPR is important,but remains experimentally challenging.We report experimental studies toward this aim using photoemission electron microscopy(PEEM)with high spatial resolution of sub-10 nm.Various engineered gold nanostructure arrays(such as rods,nanodisk-like particles and dimers)are investigated via PEEM using near-infrared(NIR)femtosecond laser pulses as the excitation source.When the LSPR wavelengths overlap the spectrum of the femtosecond pulses,the LSPR is efficiently excited and promotes multiphoton photoemission,which is correlated with the local intensity of the metallic nanoparticles in the near field.Thus,the local field distribution of the LSPR on different Au nanostructures can be directly explored and discussed using the PEEM images.In addition,the dynamics of the LSPR is studied by combining interferometric time-resolved pump-probe technique and PEEM.Detailed information on the oscillation and dephasing of the LSPR field can be obtained.The results identify PEEM as a powerful tool for accessing the near-field mapping and dynamic properties of plasmonic nanostructures.展开更多
The objective of this study was to obtain spatial distribution maps of paddy rice fields using multi-date moderate-resolution imaging spectroradiometer(MODIS) data in China.Paddy rice fields were extracted by identify...The objective of this study was to obtain spatial distribution maps of paddy rice fields using multi-date moderate-resolution imaging spectroradiometer(MODIS) data in China.Paddy rice fields were extracted by identifying the unique char-acteristic of high soil moisture in the flooding and transplanting period with improved algorithms based on rice growth calendar regionalization.The characteristic could be reflected by the enhanced vegetation index(EVI) and the land surface water index(LSWI) derived from MODIS sensor data.Algorithms for single,early,and late rice identification were obtained from selected typical test sites.The algorithms could not only separate early rice and late rice planted in the same fields,but also reduce the uncertainties.The areal accuracy of the MODIS-derived results was validated by comparison with agricultural statistics,and the spatial matching was examined by ETM+(enhanced thematic mapper plus) images in a test region.Major factors that might cause errors,such as the coarse spatial resolution and noises in the MODIS data,were discussed.Although not suitable for monitoring the inter-annual variations due to some inevitable factors,the MODIS-derived results were useful for obtaining spatial distribution maps of paddy rice on a large scale,and they might provide reference for further studies.展开更多
基金supported by the National Natural Science Foundation of China (No. 81771825)Beijing Municipal Science and Technology Commission (D1711000 03017003)Ministry of Science and Technology of China (2017YFC1307904)
文摘Objective To determine the association between the irregularity of carotid plaque surface using multidimensional magnetic resonance imaging(MRI) of ipsilateral acute cerebral infarction(ACI) cases. Methods Patients with recent cerebrovascular symptoms(stroke or transient ischemic attack < 2 weeks) and atherosclerotic plaque in at least one carotid artery were diagnosed by B-mode ultrasound imaging(intima-media thickness ≥ 1.5 mm) and recruited for the present study. Irregular surface was defined when plaque surface was uneven with high and low fluctuation or plaque with surface ulceration. The irregularity of carotid plaque surface was determined on axial or oblique images alone(single-dimension) and on both axial images and oblique images(multidimensions), separately. Univariate and multivariate logistic regression analyses were performed to calculate the odds ratio(OR) and the corresponding 95% CI of the irregular plaque surface in discriminating the presence of ipsilateral ACI. Results A total of 217 included subjects(mean age: 60.7 ± 10.2 years, 149 men) were recruited and 89(41.0%), 88(40.6%) and 118(54.4%) of them exhibited irregular plaque surface on axial, oblique and multidimensional MR images, respectively. The OR of irregularity of the plaque surface was determined by multidimensional MRI to be 5.88(95% CI: 3.16–10.96, P < 0.001) in discriminating the presence of ipsilateral ACI. Following adjustment for clinical confounding factors, this association remained statistically significant(OR = 5.65, 95% CI: 2.53–12.60, P < 0.001). The analysis included further adjustment for the presence of lipid-rich necrotic core, intraplaque hemorrhage and stenosis and the results included that this association also remained statistically significant(OR = 6.08, 95% CI: 2.52–14.68, P < 0.001). Conclusions The irregular plaque surface was determined by multidimensional MRI as an independent indicator for ipsilateral acute cerebral infarction.
基金This study was supported by funding from the Ministry of Education,Culture,Sports,Science,and Technology of Japan:KAKENHI Grant-in-Aid for Scientific Research No.23225006,Nanotechnology Platform(Hokkaido University)and the Low-Carbon Research Network of Japan.
文摘Localized surface plasmon resonance(LSPR)can be supported by metallic nanoparticles and engineered nanostructures.An understanding of the spatially resolved near-field properties and dynamics of LSPR is important,but remains experimentally challenging.We report experimental studies toward this aim using photoemission electron microscopy(PEEM)with high spatial resolution of sub-10 nm.Various engineered gold nanostructure arrays(such as rods,nanodisk-like particles and dimers)are investigated via PEEM using near-infrared(NIR)femtosecond laser pulses as the excitation source.When the LSPR wavelengths overlap the spectrum of the femtosecond pulses,the LSPR is efficiently excited and promotes multiphoton photoemission,which is correlated with the local intensity of the metallic nanoparticles in the near field.Thus,the local field distribution of the LSPR on different Au nanostructures can be directly explored and discussed using the PEEM images.In addition,the dynamics of the LSPR is studied by combining interferometric time-resolved pump-probe technique and PEEM.Detailed information on the oscillation and dephasing of the LSPR field can be obtained.The results identify PEEM as a powerful tool for accessing the near-field mapping and dynamic properties of plasmonic nanostructures.
基金supported by the National High-Tech Research and Development Program (863) of China(No.2006AA120101)the National Natural Science Foundation of China(No.40871158/D0106)the Key Technologies Research and Development Program of China(No.2006BAD10A01)
文摘The objective of this study was to obtain spatial distribution maps of paddy rice fields using multi-date moderate-resolution imaging spectroradiometer(MODIS) data in China.Paddy rice fields were extracted by identifying the unique char-acteristic of high soil moisture in the flooding and transplanting period with improved algorithms based on rice growth calendar regionalization.The characteristic could be reflected by the enhanced vegetation index(EVI) and the land surface water index(LSWI) derived from MODIS sensor data.Algorithms for single,early,and late rice identification were obtained from selected typical test sites.The algorithms could not only separate early rice and late rice planted in the same fields,but also reduce the uncertainties.The areal accuracy of the MODIS-derived results was validated by comparison with agricultural statistics,and the spatial matching was examined by ETM+(enhanced thematic mapper plus) images in a test region.Major factors that might cause errors,such as the coarse spatial resolution and noises in the MODIS data,were discussed.Although not suitable for monitoring the inter-annual variations due to some inevitable factors,the MODIS-derived results were useful for obtaining spatial distribution maps of paddy rice on a large scale,and they might provide reference for further studies.
