The firework algorithm（FWA） is a novel swarm intelligence-based method recently proposed for the optimization of multi-parameter, nonlinear functions. Numerical waveform inversion experiments using a synthetic model...The firework algorithm（FWA） is a novel swarm intelligence-based method recently proposed for the optimization of multi-parameter, nonlinear functions. Numerical waveform inversion experiments using a synthetic model show that the FWA performs well in both solution quality and efficiency. We apply the FWA in this study to crustal velocity structure inversion using regional seismic waveform data of central Gansu on the northeastern margin of the Qinghai-Tibet plateau. Seismograms recorded from the moment magnitude（MW） 5.4 Minxian earthquake enable obtaining an average crustal velocity model for this region. We initially carried out a series of FWA robustness tests in regional waveform inversion at the same earthquake and station positions across the study region,inverting two velocity structure models, with and without a low-velocity crustal layer; the accuracy of our average inversion results and their standard deviations reveal the advantages of the FWA for the inversion of regional seismic waveforms. We applied the FWA across our study area using three component waveform data recorded by nine broadband permanent seismic stations with epicentral distances ranging between 146 and 437 km. These inversion results show that the average thickness of the crust in this region is 46.75 km, while thicknesses of the sedimentary layer, and the upper, middle, and lower crust are 3.15,15.69, 13.08, and 14.83 km, respectively. Results also show that the P-wave velocities of these layers and the upper mantle are 4.47, 6.07, 6.12, 6.87, and 8.18 km/s,respectively.展开更多
Objective The accurate diagnosis of the non-specific variant of dysembryoplastic neuroepithelial tumor(DNT) is very difficult because it is characterized by absence of the histological hallmark of the "specific g...Objective The accurate diagnosis of the non-specific variant of dysembryoplastic neuroepithelial tumor(DNT) is very difficult because it is characterized by absence of the histological hallmark of the "specific glioneuronal element" in lesions. We herein present two cases of the non-specific form of DNT to analyze the clinical, radiological, and histological features of this unusual subtype of DNT.Methods A 16-year-old and a 23-year-old patient had been treated for pharmacoresistant epilepsy for several years before undergoing referral to the hospital for further examination and treatment. Magnetic resonance imaging(MRI) revealed that both patients had a small, well-demarcated cystic lesion within the cortex of the brain without obvious contrast enhancement or peritumoral edema. The lesions were totally resected and routinely examined using histological and immunohistochemical analysis.Results Both lesions exhibited similar histological appearances with cyst formation and mural nodule architecture. The glial nodules were mainly composed of oligodendrocyte-like components, and partly of piloid cells resembling pilocytic astrocytoma. The cortex adjacent to the lesion in both cases was found to have the histological features of focal cortical dysplasia(FCD) Type I. Immunohistochemically, the oligodendrocyte-like components were diffusely positive for Syn and Olig-2, but staining for CD34, p53, and IDH1 R132 H was negative. The Ki-67(MIB-1) labeling index was low, approximately 1%. There was no 1p/19 q co-deletion in either lesion by fluorescence in situ hybridization(FISH) assay. Neither patient received postoperative adjuvant treatment, and both underwent regular follow-up for at least 24 months. No signs of recurrence or epileptic attacks were observed during the follow-up period.Conclusion The non-specific variant of DNT is a diagnostic challenge for pathologists in clinical practice, and differentiation from some low-grade gliomas needs to be considered. The careful inspection of radiologic and histopathologic findings, accompanied by analysis of patients' clinical manifestations, may be helpful in making an accurate diagnosis.展开更多
During spacecraft re-entry,the challenge of measuring plasma sheath parameters directly contributes to difficulties in addressing communication blackout.In this work,we have discovered a phenomenon of multiple peaks i...During spacecraft re-entry,the challenge of measuring plasma sheath parameters directly contributes to difficulties in addressing communication blackout.In this work,we have discovered a phenomenon of multiple peaks in reflection data caused by the inhomogeneous plasma.Simulation results show that the multi-peak points fade away as the characteristic frequency is approached,resembling a series of gradually decreasing peaks.The positions and quantities of these points are positively correlated with electron density,yet they show no relation to collision frequency.This phenomenon is of significant reference value for future studies on the spatial distribution of plasmas,particularly for using microwave reflection signals in diagnosing the plasma sheath.展开更多
基金supported by the National Natural Science Foundation of China (No. 41174034)
文摘The firework algorithm（FWA） is a novel swarm intelligence-based method recently proposed for the optimization of multi-parameter, nonlinear functions. Numerical waveform inversion experiments using a synthetic model show that the FWA performs well in both solution quality and efficiency. We apply the FWA in this study to crustal velocity structure inversion using regional seismic waveform data of central Gansu on the northeastern margin of the Qinghai-Tibet plateau. Seismograms recorded from the moment magnitude（MW） 5.4 Minxian earthquake enable obtaining an average crustal velocity model for this region. We initially carried out a series of FWA robustness tests in regional waveform inversion at the same earthquake and station positions across the study region,inverting two velocity structure models, with and without a low-velocity crustal layer; the accuracy of our average inversion results and their standard deviations reveal the advantages of the FWA for the inversion of regional seismic waveforms. We applied the FWA across our study area using three component waveform data recorded by nine broadband permanent seismic stations with epicentral distances ranging between 146 and 437 km. These inversion results show that the average thickness of the crust in this region is 46.75 km, while thicknesses of the sedimentary layer, and the upper, middle, and lower crust are 3.15,15.69, 13.08, and 14.83 km, respectively. Results also show that the P-wave velocities of these layers and the upper mantle are 4.47, 6.07, 6.12, 6.87, and 8.18 km/s,respectively.
文摘Objective The accurate diagnosis of the non-specific variant of dysembryoplastic neuroepithelial tumor(DNT) is very difficult because it is characterized by absence of the histological hallmark of the "specific glioneuronal element" in lesions. We herein present two cases of the non-specific form of DNT to analyze the clinical, radiological, and histological features of this unusual subtype of DNT.Methods A 16-year-old and a 23-year-old patient had been treated for pharmacoresistant epilepsy for several years before undergoing referral to the hospital for further examination and treatment. Magnetic resonance imaging(MRI) revealed that both patients had a small, well-demarcated cystic lesion within the cortex of the brain without obvious contrast enhancement or peritumoral edema. The lesions were totally resected and routinely examined using histological and immunohistochemical analysis.Results Both lesions exhibited similar histological appearances with cyst formation and mural nodule architecture. The glial nodules were mainly composed of oligodendrocyte-like components, and partly of piloid cells resembling pilocytic astrocytoma. The cortex adjacent to the lesion in both cases was found to have the histological features of focal cortical dysplasia(FCD) Type I. Immunohistochemically, the oligodendrocyte-like components were diffusely positive for Syn and Olig-2, but staining for CD34, p53, and IDH1 R132 H was negative. The Ki-67(MIB-1) labeling index was low, approximately 1%. There was no 1p/19 q co-deletion in either lesion by fluorescence in situ hybridization(FISH) assay. Neither patient received postoperative adjuvant treatment, and both underwent regular follow-up for at least 24 months. No signs of recurrence or epileptic attacks were observed during the follow-up period.Conclusion The non-specific variant of DNT is a diagnostic challenge for pathologists in clinical practice, and differentiation from some low-grade gliomas needs to be considered. The careful inspection of radiologic and histopathologic findings, accompanied by analysis of patients' clinical manifestations, may be helpful in making an accurate diagnosis.
文摘During spacecraft re-entry,the challenge of measuring plasma sheath parameters directly contributes to difficulties in addressing communication blackout.In this work,we have discovered a phenomenon of multiple peaks in reflection data caused by the inhomogeneous plasma.Simulation results show that the multi-peak points fade away as the characteristic frequency is approached,resembling a series of gradually decreasing peaks.The positions and quantities of these points are positively correlated with electron density,yet they show no relation to collision frequency.This phenomenon is of significant reference value for future studies on the spatial distribution of plasmas,particularly for using microwave reflection signals in diagnosing the plasma sheath.
