基于聚焦性能对经颅磁线圈的影响,针对聚焦型线圈商用不足的问题,设计一种具有高聚焦性的单通道双梯形双层线圈。首先使用球头模型分析不同尺寸、相同结构的线圈性能,得到较优的线圈尺寸;为进一步提升聚焦度,再以中尺寸线圈为研究目标,...基于聚焦性能对经颅磁线圈的影响,针对聚焦型线圈商用不足的问题,设计一种具有高聚焦性的单通道双梯形双层线圈。首先使用球头模型分析不同尺寸、相同结构的线圈性能,得到较优的线圈尺寸;为进一步提升聚焦度,再以中尺寸线圈为研究目标,探讨五种不同结构的双层线圈与两种商用8字形线圈的性能差异,得到最优线圈的结构;最后使用50组存在个体差异性的真实脑模型进行仿真验证,分析球头模型结果的可靠性。仿真结果表明:使用球头模型时,优化后的新型线圈对比70 mm figure-8 coil的聚焦度提升了69.48%,刺激深度减少了27.18%;对比25 mm figure-8 coil的聚焦度提升了44.78%,刺激深度减少了8.5%;使用50组真实脑模型时,优化后的新型线圈对比70 mm figure-8 coil的聚焦度提升了62.07%,刺激深度减少了25.71%;对比25 mm figure-8 coil的聚焦度提升了39.49%,刺激深度减少了9.5%。两种模型仿真数据结果趋于一致,证实了仿真可靠性的同时也证明了新型线圈具有更强的刺激强度和聚焦度,能大大提升TMS治疗的安全性,减少不适感,同时单通道设计易于实现,具有较高的性能优势。展开更多
We clarified the characteristics of pulsed electromagnetic field (PEMF) strength in marrow cavity with bone marrow in long bones based on actual measurements taken during pulsed magnetic stimulation (PMS). Measurement...We clarified the characteristics of pulsed electromagnetic field (PEMF) strength in marrow cavity with bone marrow in long bones based on actual measurements taken during pulsed magnetic stimulation (PMS). Measurements were made under 810 different conditions of stimulation intensity, distance, and position. Significant and strong linear correlations were observed between PEMF strength and stimulation intensity. PEMF strength in marrow cavity during PMS showed an exponential decay depending on coil-sensor distance, with a breaking point at approximately 30 mm. PEMF strength distributions in bone showed geometric differences between 3 types. These findings suggest that PEMF strength in bone depends on stimulation intensity, distance and horizontal position. Our actual measured data could be useful in determining stimulation programs and estimating the in vivo efficacy of PEMF in marrow cavity for research and clinical use.展开更多
经颅磁刺激(transcranial magnetic stimulation,TMS)技术因其无痛、无创的优点已在临床的治疗和诊断中得到广泛的应用,而如何提高刺激线圈的聚焦度和灵活性仍是1个亟待解决问题。提出了双8字形刺激线圈,研究了双8字形线圈内外线圈的半...经颅磁刺激(transcranial magnetic stimulation,TMS)技术因其无痛、无创的优点已在临床的治疗和诊断中得到广泛的应用,而如何提高刺激线圈的聚焦度和灵活性仍是1个亟待解决问题。提出了双8字形刺激线圈,研究了双8字形线圈内外线圈的半径比及匝数比对刺激聚焦度的影响;并利用COMSOL仿真软件探究了圆形线圈阵列的刺激特性以及辅助线圈对刺激性能的影响。结果表明:双8字形线圈的聚焦度较普通8字形线圈其聚焦度最大可提高50%;圆形线圈阵列可通过控制独立线圈电流来灵活调节刺激模式,适当引入辅助线圈电流能有效提高线圈阵列的刺激聚焦度,但辅助线圈电流与主线圈电流之比应小于0.4。展开更多
A model of magnetic stimulation is presented for analysis of the spatial distributions of the electric field induced by magnetic coils.Dimensionless analysis is introduced and makes the factors influencing the magnitu...A model of magnetic stimulation is presented for analysis of the spatial distributions of the electric field induced by magnetic coils.Dimensionless analysis is introduced and makes the factors influencing the magnitude of electric field into two parts:c (represents the stimulation conditions),and E 0 (reflects the geometry of coil).By 3 D simulation of the induced electric field of two kinds of coils,the effect of magnetic stimulation can be demonstrated and the factors influencing stimulating focality and depth are identified.The principles for determining the electric field magnitude,focality and magnetic stimulation depth when designing a reasonable coil and stimulator and achieving ideal stimulating effect are discussed.展开更多
Dozens of >M5, hundreds of >M4, and much more >M3 aftershocks occurred after the 2008/05/12 Wenchuan earthquake, which were well recorded by permanent and portable seismic stations. After relocated with P arr...Dozens of >M5, hundreds of >M4, and much more >M3 aftershocks occurred after the 2008/05/12 Wenchuan earthquake, which were well recorded by permanent and portable seismic stations. After relocated with P arrival, the >M3 aftershocks show two trends of distribution, with most of the aftershocks located along the north-east strike consistent with Longmenshan fault system, yet there is a north-west trend around the epicenter. It seems that substantially more aftershocks occur in regions with crystalline bedrocks. Then we collected waveform data from National Digital Seismograph Network and regional seismograph network of China, and employed 'Cut and Paste' method to obtain focal mechanisms and depths of the big aftershocks (M≥5.6). While most of those aftershocks show thrust mechanism, there are some strike slip earthquakes in the northern-most end of the rupture. Focal mechanisms show that the events located on the southern part of central Beichuan-Yingxiu Fault (BY) are mainly thrust earthquakes, which is consistent with initial mechanism of the main shock rupture. In the north part the aftershocks along the BY are also dominated by thrust slip, which is quite different from the right slip rupture of the main shock. Around Qingchuan-Pingwu Fault, the focal mechanisms are dominated by right-slip rupture with large depths (~18 km). So we suspected that in the north part the main shock might rupture on two faults: Beichuan Fault and Qingchuan-Pingwu Fault. The complex pattern of aftershock mechanisms argues for presence of a complicated fault system in the Longmenshan area.展开更多
The contemporary tectonic stress field in China is obtained on the basis of Chinese stress field database and Harvard CMT catalogue. Result of the inverted tectonic stresses shows that the maximum principal stress axi...The contemporary tectonic stress field in China is obtained on the basis of Chinese stress field database and Harvard CMT catalogue. Result of the inverted tectonic stresses shows that the maximum principal stress axis strikes nearly north-south direction in the west part of Tibet plateau, ENE direction in North China. In Central China, its strikes show a ra- diated pattern, i.e., NNE in north part and NNW in south part. The detailed stress field parameters of nearly whole China are given and can be used in geodynamic stress field simulation and earthquake prediction.展开更多
Objective To investigate whether pretreatment with repeated electroacupuncture (EA)at the Baihui acupoint could induce ischemic tolerance against transient focal cerebral ischemic injury in rats. Methods Thirty mal...Objective To investigate whether pretreatment with repeated electroacupuncture (EA)at the Baihui acupoint could induce ischemic tolerance against transient focal cerebral ischemic injury in rats. Methods Thirty male Sprague-Dawley (SD) rats were randomly divided into 3 groups (n=10 for each): the control group consisted of animals receiving no treatment, the isoflurane (ISO) group had animals that inhaled 1.5% isoflurane for 30 min a day for 5 days, and animals in the EA group received electroacupuncture at the Baihui acupoint for 30 min a day for 5 days under 1.5% isoflurane anesthesia. Twenty-four hours after the last treatment, the middle cerebral artery was occluded with No. 3 nylon monofilament for 120 min. The neurological outcomes were evaluated 24 h after reperfusion. The infarct volumes were then assessed using 2% triphenyltetrazolium chloride staining after the neurological outcome evaluation. Results The neurological deficit score (NDS) of the EA group was lower than that of the ISO group and the control group , P<0.05. The infarct volume of the EA group (38.3±25.4 mm 3) was significantly smaller than that of the control group (220.5±66.0 mm 3) and the ISO group (168.6±57.6 mm 3) 24 h after reperfusion. Conclusion Electroacupuncture at the Baihui acupoint 30 min a day for 5 days significantly reduces neurological injury induced by transient middle cerebral artery occlusion.展开更多
This study was designed to determine if repeated hyperbaric oxygen (HBO) exposure induces ischemic tolerance in focal cerebral ischemia Methods Sixty male SD rats were used in this study Thirty animals underw...This study was designed to determine if repeated hyperbaric oxygen (HBO) exposure induces ischemic tolerance in focal cerebral ischemia Methods Sixty male SD rats were used in this study Thirty animals underwent transient middle cerebral artery occlusion (MCAO) and the other thirty permanent MCAO model The rats were randomly allocated to 3 sub-groups: control group (n=10), HBO-3 group (n=10), and HBO-5 group (n=10) The animals in HBO-3 and HBO-5 groups received 1*!hour hyperbaric oxygenation at 2 5 atmosphere absolute (ATA) in 100% oxygen every day for 3 and 5 days, respectively The animals in the control group received sham treatments 24*!hours after the last HBO, transient MCAO (120 min) and permanent MCAO were induced by introducing a 3-0 nylon monofilament suture through internal carotid artery based on the Koizumi technique The neurological outcome was evaluated until 24*!hours after reperfusion in transient MCAO rats and ischemia in permanent MCAO rats The infarct volume was then assessed by TTC staining Results In transient MCAO rats, the neurological outcome in both the HBO-3 and HBO-5 groups was better than that of the control group ( P <0 05 and 0 001) The infarct volume decreased from 171 5±113*!mm 3 to 40 6±49 9*!mm 3 ( P <0 05) in the HBO-3 group and 16 2±28 8*!mm 3 ( P <0 01) in the HBO-5 group There were no significant differences in neurological outcome and infarct volume among the three groups in permanent MCAO rats Conclusions The present study demonstrated that HBO preconditioning can induce ischemic tolerance in transient not permanent MCAO rats in a “dose-dependent' manner展开更多
Stress field plays a key role in geodynamics. In this study, an algorithm to determine the stress tensor and its confidence range from focal mechanism data by using grid search method was proposed. The experiment uses...Stress field plays a key role in geodynamics. In this study, an algorithm to determine the stress tensor and its confidence range from focal mechanism data by using grid search method was proposed. The experiment uses artificial focal mechanism data which were generated by extensional, compression and strike-slip stress regime and different level of noise, shows that the precision of the estimated stress tensor based on this algorithm is greatly improved compared with traditional algorithms. This algorithm has three advantages：（1） The global optimal solution of the stress tensor is determined by fine grid search of 1o×1o×1o×0.01 and local minimum value is avoided; （2） precision of focal mechanism data can be considered, i.e., different weight of the focal mechanism data contributes differently to the process of determining stress tensor; （3） the confidence range of the determined stress tensor can be obtained by using F-test. We apply this algorithm in the boundary zone of China, Vietnam and Laos, and obtain the stress field with SSE-NNW compressive stress direction and NEE-SWW extensional stress direction. The stress ratio is 0.6, which shows that the eigen values of the stress tensor are nearly in arithmetic sequence. The stress field in this region is consistent with the left-lateral strike slip of the Dienbien-Lauangphrabang arc fault. The result will be helpful in studying the geological dynamic process in this region.展开更多
文摘基于聚焦性能对经颅磁线圈的影响,针对聚焦型线圈商用不足的问题,设计一种具有高聚焦性的单通道双梯形双层线圈。首先使用球头模型分析不同尺寸、相同结构的线圈性能,得到较优的线圈尺寸;为进一步提升聚焦度,再以中尺寸线圈为研究目标,探讨五种不同结构的双层线圈与两种商用8字形线圈的性能差异,得到最优线圈的结构;最后使用50组存在个体差异性的真实脑模型进行仿真验证,分析球头模型结果的可靠性。仿真结果表明:使用球头模型时,优化后的新型线圈对比70 mm figure-8 coil的聚焦度提升了69.48%,刺激深度减少了27.18%;对比25 mm figure-8 coil的聚焦度提升了44.78%,刺激深度减少了8.5%;使用50组真实脑模型时,优化后的新型线圈对比70 mm figure-8 coil的聚焦度提升了62.07%,刺激深度减少了25.71%;对比25 mm figure-8 coil的聚焦度提升了39.49%,刺激深度减少了9.5%。两种模型仿真数据结果趋于一致,证实了仿真可靠性的同时也证明了新型线圈具有更强的刺激强度和聚焦度,能大大提升TMS治疗的安全性,减少不适感,同时单通道设计易于实现,具有较高的性能优势。
文摘We clarified the characteristics of pulsed electromagnetic field (PEMF) strength in marrow cavity with bone marrow in long bones based on actual measurements taken during pulsed magnetic stimulation (PMS). Measurements were made under 810 different conditions of stimulation intensity, distance, and position. Significant and strong linear correlations were observed between PEMF strength and stimulation intensity. PEMF strength in marrow cavity during PMS showed an exponential decay depending on coil-sensor distance, with a breaking point at approximately 30 mm. PEMF strength distributions in bone showed geometric differences between 3 types. These findings suggest that PEMF strength in bone depends on stimulation intensity, distance and horizontal position. Our actual measured data could be useful in determining stimulation programs and estimating the in vivo efficacy of PEMF in marrow cavity for research and clinical use.
文摘经颅磁刺激(transcranial magnetic stimulation,TMS)技术因其无痛、无创的优点已在临床的治疗和诊断中得到广泛的应用,而如何提高刺激线圈的聚焦度和灵活性仍是1个亟待解决问题。提出了双8字形刺激线圈,研究了双8字形线圈内外线圈的半径比及匝数比对刺激聚焦度的影响;并利用COMSOL仿真软件探究了圆形线圈阵列的刺激特性以及辅助线圈对刺激性能的影响。结果表明:双8字形线圈的聚焦度较普通8字形线圈其聚焦度最大可提高50%;圆形线圈阵列可通过控制独立线圈电流来灵活调节刺激模式,适当引入辅助线圈电流能有效提高线圈阵列的刺激聚焦度,但辅助线圈电流与主线圈电流之比应小于0.4。
文摘A model of magnetic stimulation is presented for analysis of the spatial distributions of the electric field induced by magnetic coils.Dimensionless analysis is introduced and makes the factors influencing the magnitude of electric field into two parts:c (represents the stimulation conditions),and E 0 (reflects the geometry of coil).By 3 D simulation of the induced electric field of two kinds of coils,the effect of magnetic stimulation can be demonstrated and the factors influencing stimulating focality and depth are identified.The principles for determining the electric field magnitude,focality and magnetic stimulation depth when designing a reasonable coil and stimulator and achieving ideal stimulating effect are discussed.
基金Supported by Knowledge Innovation Project of Chinese Academy of Sciences (Grant Nos. KZCX3-SW-153, KZCX2-YW-116-1)National Natural Science Foundation of China (Grant No. 40604004)National Basic Technology R & D Program (GrantNo. 2006BAC01B02-01-02)
文摘Dozens of >M5, hundreds of >M4, and much more >M3 aftershocks occurred after the 2008/05/12 Wenchuan earthquake, which were well recorded by permanent and portable seismic stations. After relocated with P arrival, the >M3 aftershocks show two trends of distribution, with most of the aftershocks located along the north-east strike consistent with Longmenshan fault system, yet there is a north-west trend around the epicenter. It seems that substantially more aftershocks occur in regions with crystalline bedrocks. Then we collected waveform data from National Digital Seismograph Network and regional seismograph network of China, and employed 'Cut and Paste' method to obtain focal mechanisms and depths of the big aftershocks (M≥5.6). While most of those aftershocks show thrust mechanism, there are some strike slip earthquakes in the northern-most end of the rupture. Focal mechanisms show that the events located on the southern part of central Beichuan-Yingxiu Fault (BY) are mainly thrust earthquakes, which is consistent with initial mechanism of the main shock rupture. In the north part the aftershocks along the BY are also dominated by thrust slip, which is quite different from the right slip rupture of the main shock. Around Qingchuan-Pingwu Fault, the focal mechanisms are dominated by right-slip rupture with large depths (~18 km). So we suspected that in the north part the main shock might rupture on two faults: Beichuan Fault and Qingchuan-Pingwu Fault. The complex pattern of aftershock mechanisms argues for presence of a complicated fault system in the Longmenshan area.
基金supported by the National Natural Science Foundation of China (40874022)Public Utility Research Project (200808053)973 program (2008CB425703)
文摘The contemporary tectonic stress field in China is obtained on the basis of Chinese stress field database and Harvard CMT catalogue. Result of the inverted tectonic stresses shows that the maximum principal stress axis strikes nearly north-south direction in the west part of Tibet plateau, ENE direction in North China. In Central China, its strikes show a ra- diated pattern, i.e., NNE in north part and NNW in south part. The detailed stress field parameters of nearly whole China are given and can be used in geodynamic stress field simulation and earthquake prediction.
基金ThisstudywassupportedinpartbyagrantfromtheNationalNaturalScienceFoundationofChina (No 30 170 90 7)
文摘Objective To investigate whether pretreatment with repeated electroacupuncture (EA)at the Baihui acupoint could induce ischemic tolerance against transient focal cerebral ischemic injury in rats. Methods Thirty male Sprague-Dawley (SD) rats were randomly divided into 3 groups (n=10 for each): the control group consisted of animals receiving no treatment, the isoflurane (ISO) group had animals that inhaled 1.5% isoflurane for 30 min a day for 5 days, and animals in the EA group received electroacupuncture at the Baihui acupoint for 30 min a day for 5 days under 1.5% isoflurane anesthesia. Twenty-four hours after the last treatment, the middle cerebral artery was occluded with No. 3 nylon monofilament for 120 min. The neurological outcomes were evaluated 24 h after reperfusion. The infarct volumes were then assessed using 2% triphenyltetrazolium chloride staining after the neurological outcome evaluation. Results The neurological deficit score (NDS) of the EA group was lower than that of the ISO group and the control group , P<0.05. The infarct volume of the EA group (38.3±25.4 mm 3) was significantly smaller than that of the control group (220.5±66.0 mm 3) and the ISO group (168.6±57.6 mm 3) 24 h after reperfusion. Conclusion Electroacupuncture at the Baihui acupoint 30 min a day for 5 days significantly reduces neurological injury induced by transient middle cerebral artery occlusion.
基金ThisstudywassupportedinpartbyagrantfromtheNationalNaturalScienceFoundationofChina (No 396 70 6 99)
文摘This study was designed to determine if repeated hyperbaric oxygen (HBO) exposure induces ischemic tolerance in focal cerebral ischemia Methods Sixty male SD rats were used in this study Thirty animals underwent transient middle cerebral artery occlusion (MCAO) and the other thirty permanent MCAO model The rats were randomly allocated to 3 sub-groups: control group (n=10), HBO-3 group (n=10), and HBO-5 group (n=10) The animals in HBO-3 and HBO-5 groups received 1*!hour hyperbaric oxygenation at 2 5 atmosphere absolute (ATA) in 100% oxygen every day for 3 and 5 days, respectively The animals in the control group received sham treatments 24*!hours after the last HBO, transient MCAO (120 min) and permanent MCAO were induced by introducing a 3-0 nylon monofilament suture through internal carotid artery based on the Koizumi technique The neurological outcome was evaluated until 24*!hours after reperfusion in transient MCAO rats and ischemia in permanent MCAO rats The infarct volume was then assessed by TTC staining Results In transient MCAO rats, the neurological outcome in both the HBO-3 and HBO-5 groups was better than that of the control group ( P <0 05 and 0 001) The infarct volume decreased from 171 5±113*!mm 3 to 40 6±49 9*!mm 3 ( P <0 05) in the HBO-3 group and 16 2±28 8*!mm 3 ( P <0 01) in the HBO-5 group There were no significant differences in neurological outcome and infarct volume among the three groups in permanent MCAO rats Conclusions The present study demonstrated that HBO preconditioning can induce ischemic tolerance in transient not permanent MCAO rats in a “dose-dependent' manner
基金supported by Natural Science Foundation of China(No.41674055)the Earthquake Science and Technology Spark Plan in Hebei Province(DZ20140101002)
文摘Stress field plays a key role in geodynamics. In this study, an algorithm to determine the stress tensor and its confidence range from focal mechanism data by using grid search method was proposed. The experiment uses artificial focal mechanism data which were generated by extensional, compression and strike-slip stress regime and different level of noise, shows that the precision of the estimated stress tensor based on this algorithm is greatly improved compared with traditional algorithms. This algorithm has three advantages：（1） The global optimal solution of the stress tensor is determined by fine grid search of 1o×1o×1o×0.01 and local minimum value is avoided; （2） precision of focal mechanism data can be considered, i.e., different weight of the focal mechanism data contributes differently to the process of determining stress tensor; （3） the confidence range of the determined stress tensor can be obtained by using F-test. We apply this algorithm in the boundary zone of China, Vietnam and Laos, and obtain the stress field with SSE-NNW compressive stress direction and NEE-SWW extensional stress direction. The stress ratio is 0.6, which shows that the eigen values of the stress tensor are nearly in arithmetic sequence. The stress field in this region is consistent with the left-lateral strike slip of the Dienbien-Lauangphrabang arc fault. The result will be helpful in studying the geological dynamic process in this region.
