Acoustic modal behavior is reported for an L-shape hydrophone array during the passage of a strong nonlinear internal wave packet. Acoustic track is nearly parallel to the front of nonlinear internal waves. Through mo...Acoustic modal behavior is reported for an L-shape hydrophone array during the passage of a strong nonlinear internal wave packet. Acoustic track is nearly parallel to the front of nonlinear internal waves. Through modal decomposition at the vertical array, acoustic modes are identified. Modal evolution along the horizontal array then is examined during a passing internal wave. Strong intensity fluctuations of individual modes are observed before and during the internal waves packet passes the fixed acoustic track showing a detailed evolution of the waveguide modal behavior. Acoustic refraction created either uneven distribution of modal energy over the horizontal array or additional returns observable at the entire L-shape array. Acoustic ray-mode simulations are used to phenomenologically explain the observed modal behavior.展开更多
Pilot-assisted channel estimation has been investigated to improve the performance of OFDM based LTE systems. LS and MMSE method do not perform excellently because they do not consider the inherent sparse feature of w...Pilot-assisted channel estimation has been investigated to improve the performance of OFDM based LTE systems. LS and MMSE method do not perform excellently because they do not consider the inherent sparse feature of wireless channel. The sparse feature of channel impulse response satisfies the requirement of using compressive sensing (CS) theory, which has recently gained much attention in signal processing. Result in the application of using compressive sensing to estimate fading channel. And it achieves a much better performance than that with traditional methods. In this paper, we propose heuristic channel estimation based on CS in LTE Downlink channel. According to the feature of recovery algorithm in CS, we design a modified pilot placement method. CS recovery algorithms for channel estimation don’t consider the statistics character of channel. So we proposed an optimization method which combines the CS and noise reduction. First we get initial channel statistics obtained by LS. Let the channel statistics as the heuristic information input of CS recovery algorithm. Then we perform CS recovery algorithm to estimate channel. Simulation results show this approach significantly reduces the complexity of channel estimation and get a better mean square error (MSE) performance.展开更多
目的研究在外加磁场作用下^(131)I-VEGF si RNA/SPIO在人肝细胞癌移植瘤裸鼠体内的血液清除动力学及生物分布特性。方法以Bolton-Hunter法使VEGF si RNA标记上^(131)I,以氧化铁超顺磁性纳米颗粒(superparamagneticiron oxide nanopartic...目的研究在外加磁场作用下^(131)I-VEGF si RNA/SPIO在人肝细胞癌移植瘤裸鼠体内的血液清除动力学及生物分布特性。方法以Bolton-Hunter法使VEGF si RNA标记上^(131)I,以氧化铁超顺磁性纳米颗粒(superparamagneticiron oxide nanoparticles,SPIO)包裹^(131)I-VEGF si RNA。以人肝细胞癌细胞株Hep G2细胞悬液臀部皮下注射建立人肝细胞癌移植瘤裸鼠模型。45只人肝细胞癌移植瘤裸鼠随机分成外加磁场组(尾静脉注射^(131)I-VEGF si RNA/SPIO+肿瘤部位外加磁场)、非外加磁场组(尾静脉注射^(131)I-VEGF si RNA/SPIO+肿瘤部位无外加磁场)及对照组(尾静脉注射^(131)I-VEGF si RNA+肿瘤部位无外加磁场)。然后进行:(1)血液清除动力学研究:三组人肝细胞癌移植瘤裸鼠(每组5只)尾静脉给药后,分别于0.5 h、1.0 h、1.5 h、2.0 h、3.0 h、4.0 h、6.0 h、8.0 h、10.0 h、12.0 h时间点尾静脉采血20μL,测量血样每分钟放射性计数(counts per minute,cpm)值并绘制放射性-时间曲线,计算血液半衰期;(2)体内生物分布研究:三组人肝细胞癌移植瘤裸鼠尾静脉给药1 h后进行SPECT显像(每组5只)及MRI显像(每组5只),SPECT及MRI显像完毕,依次摘取移植瘤裸鼠肿瘤、皮肤、肌肉、骨、甲状腺、胃、小肠、大肠、肺、脾、性腺、肝、心、肾、膀胱等脏器称重并测量cpm值,然后计算各离体组织的%ID/g[即组织的放射性比活度(cpm/g)/注入标记物的放射性比活度(cpm/g)]。结果本研究分别以薄层层析硅胶板为载体、1∶1丙酮-生理盐水为展开剂和以新华一号滤纸为载体、1∶1甲醇-5%醋酸铵为展开剂测定^(131)I标记VEGF si RNA的放化纯分别为81.15%和84.05%。外加磁场组、非外加磁场组及对照组移植瘤裸鼠的血液半衰期分别约为(2.27±0.14)h、(2.93±0.20)h和(3.06±0.23)h,外加磁场组半衰期小于其它两组(差异有统计学意义,P<0.01)。SPECT显像显示外加磁场组肿瘤局部明显放射性增浓,非外加磁场组及对照组肿瘤局部未见明显放射性增浓;尾静脉给药前后MRI T1WI显示外加磁场组肿瘤局部信号明显强化,非外加磁场组及对照组肿瘤局部信号未见明显强化;外加磁场组肿瘤组织的%ID/g分布较非外加磁场组及对照组的均明显增高(P<0.01)。结论在外加磁场的作用下,以SPIO作为si RNA载体能够较成功地将^(131)I-VEGF si RNA转导至人肝细胞癌移植瘤裸鼠臀部皮下的肿瘤部位,对进一步研究肝细胞癌的VEGF靶向治疗、基因治疗以及示踪体内基因转导均有重要的意义。展开更多
目的探讨腺苷酸活化蛋白激酶(adenosine monophosphate activated protein kinase,AMPK)、Yes相关蛋白1(yes-associated protein 1,YAP1)、E-cadherin蛋白在胃癌组织中的表达与临床各病理特征的关系。方法选取2019年1月至2020年1月在宁...目的探讨腺苷酸活化蛋白激酶(adenosine monophosphate activated protein kinase,AMPK)、Yes相关蛋白1(yes-associated protein 1,YAP1)、E-cadherin蛋白在胃癌组织中的表达与临床各病理特征的关系。方法选取2019年1月至2020年1月在宁夏医科大学总医院行胃癌根治术患者的组织标本60例,采用免疫组化法检测AMPK、YAP1、E-cadherin在胃癌组织和相应癌旁正常组织中的表达,统计各基因在胃癌组织中的表达阳性率,分析其与临床各病理特征的关系;进一步分析胃癌组织中AMPK、YAP1、E-cadherin蛋白表达的相关性。结果60例胃癌组织中,AMPK、YAP1、E-cadherin的蛋白表达阳性率分别为40.00%、80.00%、36.67%,而癌旁正常组织中的表达阳性率分别为85.00%、28.33%、75.00%;AMPK、E-cadherin在胃癌组织中的表达阳性率均低于癌旁组织(P均<0.05),YAP1在胃癌组织中的表达阳性率高于癌旁组织(P<0.05)。AMPK的表达与脉管浸润、肿瘤分化程度、淋巴结转移及TNM分期相关(P均<0.05),而与性别、年龄、肿瘤大小无关(P均>0.05);YAP1的表达与肿瘤大小、脉管浸润、肿瘤分化程度、淋巴结转移及TNM分期相关(P均<0.05),而与性别、年龄无关(P均<0.05);E-cadherin的表达与脉管浸润、淋巴结转移及TNM分期相关(P均<0.05),与性别、年龄、肿瘤大小、肿瘤分化程度无关(P均>0.05)。AMPK与YAP1的表达呈负相关(P<0.01),与E-cadherin的表达呈正相关(P<0.01),YAP1与E-cadherin的表达呈负相关(P<0.01)。结论AMPK、YAP1、E-cadherin蛋白均在胃癌组织中异常表达,与胃癌的进展有一定相关性,联合检测可能对胃癌的诊治具有指导价值。展开更多
The patterns of material accumulation in buildings and infrastructure accompanied by rapid urbanization offer an important,yet hitherto largely missing stock perspective for facilitating urban system engineering and i...The patterns of material accumulation in buildings and infrastructure accompanied by rapid urbanization offer an important,yet hitherto largely missing stock perspective for facilitating urban system engineering and informing urban resources,waste,and climate strategies.However,our existing knowledge on the patterns of built environment stocks across and particularly within cities is limited,largely owing to the lack of sufficient high spatial resolution data.This study leveraged multi-source big geodata,machine learning,and bottom-up stock accounting to characterize the built environment stocks of 50 cities in China at 500 m fine-grained levels.The per capita built environment stock of many cities(261 tonnes per capita on average)is close to that in western cities,despite considerable disparities across cities owing to their varying socioeconomic,geomorphology,and urban form characteristics.This is mainly owing to the construction boom and the building and infrastructure-driven economy of China in the past decades.China’s urban expansion tends to be more“vertical”(with high-rise buildings)than“horizontal”(with expanded road networks).It trades skylines for space,and reflects a concentration-dispersion-concentration pathway for spatialized built environment stocks development within cities in China.These results shed light on future urbanization in developing cities,inform spatial planning,and support circular and low-carbon transitions in cities.展开更多
基金Supported by U.S. Office of Naval Research,Ocean Acoustics Program(322OA)under Nos.N00014-11-1-0701 and N00014-13-1-0306
文摘Acoustic modal behavior is reported for an L-shape hydrophone array during the passage of a strong nonlinear internal wave packet. Acoustic track is nearly parallel to the front of nonlinear internal waves. Through modal decomposition at the vertical array, acoustic modes are identified. Modal evolution along the horizontal array then is examined during a passing internal wave. Strong intensity fluctuations of individual modes are observed before and during the internal waves packet passes the fixed acoustic track showing a detailed evolution of the waveguide modal behavior. Acoustic refraction created either uneven distribution of modal energy over the horizontal array or additional returns observable at the entire L-shape array. Acoustic ray-mode simulations are used to phenomenologically explain the observed modal behavior.
文摘Pilot-assisted channel estimation has been investigated to improve the performance of OFDM based LTE systems. LS and MMSE method do not perform excellently because they do not consider the inherent sparse feature of wireless channel. The sparse feature of channel impulse response satisfies the requirement of using compressive sensing (CS) theory, which has recently gained much attention in signal processing. Result in the application of using compressive sensing to estimate fading channel. And it achieves a much better performance than that with traditional methods. In this paper, we propose heuristic channel estimation based on CS in LTE Downlink channel. According to the feature of recovery algorithm in CS, we design a modified pilot placement method. CS recovery algorithms for channel estimation don’t consider the statistics character of channel. So we proposed an optimization method which combines the CS and noise reduction. First we get initial channel statistics obtained by LS. Let the channel statistics as the heuristic information input of CS recovery algorithm. Then we perform CS recovery algorithm to estimate channel. Simulation results show this approach significantly reduces the complexity of channel estimation and get a better mean square error (MSE) performance.
文摘目的研究在外加磁场作用下^(131)I-VEGF si RNA/SPIO在人肝细胞癌移植瘤裸鼠体内的血液清除动力学及生物分布特性。方法以Bolton-Hunter法使VEGF si RNA标记上^(131)I,以氧化铁超顺磁性纳米颗粒(superparamagneticiron oxide nanoparticles,SPIO)包裹^(131)I-VEGF si RNA。以人肝细胞癌细胞株Hep G2细胞悬液臀部皮下注射建立人肝细胞癌移植瘤裸鼠模型。45只人肝细胞癌移植瘤裸鼠随机分成外加磁场组(尾静脉注射^(131)I-VEGF si RNA/SPIO+肿瘤部位外加磁场)、非外加磁场组(尾静脉注射^(131)I-VEGF si RNA/SPIO+肿瘤部位无外加磁场)及对照组(尾静脉注射^(131)I-VEGF si RNA+肿瘤部位无外加磁场)。然后进行:(1)血液清除动力学研究:三组人肝细胞癌移植瘤裸鼠(每组5只)尾静脉给药后,分别于0.5 h、1.0 h、1.5 h、2.0 h、3.0 h、4.0 h、6.0 h、8.0 h、10.0 h、12.0 h时间点尾静脉采血20μL,测量血样每分钟放射性计数(counts per minute,cpm)值并绘制放射性-时间曲线,计算血液半衰期;(2)体内生物分布研究:三组人肝细胞癌移植瘤裸鼠尾静脉给药1 h后进行SPECT显像(每组5只)及MRI显像(每组5只),SPECT及MRI显像完毕,依次摘取移植瘤裸鼠肿瘤、皮肤、肌肉、骨、甲状腺、胃、小肠、大肠、肺、脾、性腺、肝、心、肾、膀胱等脏器称重并测量cpm值,然后计算各离体组织的%ID/g[即组织的放射性比活度(cpm/g)/注入标记物的放射性比活度(cpm/g)]。结果本研究分别以薄层层析硅胶板为载体、1∶1丙酮-生理盐水为展开剂和以新华一号滤纸为载体、1∶1甲醇-5%醋酸铵为展开剂测定^(131)I标记VEGF si RNA的放化纯分别为81.15%和84.05%。外加磁场组、非外加磁场组及对照组移植瘤裸鼠的血液半衰期分别约为(2.27±0.14)h、(2.93±0.20)h和(3.06±0.23)h,外加磁场组半衰期小于其它两组(差异有统计学意义,P<0.01)。SPECT显像显示外加磁场组肿瘤局部明显放射性增浓,非外加磁场组及对照组肿瘤局部未见明显放射性增浓;尾静脉给药前后MRI T1WI显示外加磁场组肿瘤局部信号明显强化,非外加磁场组及对照组肿瘤局部信号未见明显强化;外加磁场组肿瘤组织的%ID/g分布较非外加磁场组及对照组的均明显增高(P<0.01)。结论在外加磁场的作用下,以SPIO作为si RNA载体能够较成功地将^(131)I-VEGF si RNA转导至人肝细胞癌移植瘤裸鼠臀部皮下的肿瘤部位,对进一步研究肝细胞癌的VEGF靶向治疗、基因治疗以及示踪体内基因转导均有重要的意义。
文摘目的探讨腺苷酸活化蛋白激酶(adenosine monophosphate activated protein kinase,AMPK)、Yes相关蛋白1(yes-associated protein 1,YAP1)、E-cadherin蛋白在胃癌组织中的表达与临床各病理特征的关系。方法选取2019年1月至2020年1月在宁夏医科大学总医院行胃癌根治术患者的组织标本60例,采用免疫组化法检测AMPK、YAP1、E-cadherin在胃癌组织和相应癌旁正常组织中的表达,统计各基因在胃癌组织中的表达阳性率,分析其与临床各病理特征的关系;进一步分析胃癌组织中AMPK、YAP1、E-cadherin蛋白表达的相关性。结果60例胃癌组织中,AMPK、YAP1、E-cadherin的蛋白表达阳性率分别为40.00%、80.00%、36.67%,而癌旁正常组织中的表达阳性率分别为85.00%、28.33%、75.00%;AMPK、E-cadherin在胃癌组织中的表达阳性率均低于癌旁组织(P均<0.05),YAP1在胃癌组织中的表达阳性率高于癌旁组织(P<0.05)。AMPK的表达与脉管浸润、肿瘤分化程度、淋巴结转移及TNM分期相关(P均<0.05),而与性别、年龄、肿瘤大小无关(P均>0.05);YAP1的表达与肿瘤大小、脉管浸润、肿瘤分化程度、淋巴结转移及TNM分期相关(P均<0.05),而与性别、年龄无关(P均<0.05);E-cadherin的表达与脉管浸润、淋巴结转移及TNM分期相关(P均<0.05),与性别、年龄、肿瘤大小、肿瘤分化程度无关(P均>0.05)。AMPK与YAP1的表达呈负相关(P<0.01),与E-cadherin的表达呈正相关(P<0.01),YAP1与E-cadherin的表达呈负相关(P<0.01)。结论AMPK、YAP1、E-cadherin蛋白均在胃癌组织中异常表达,与胃癌的进展有一定相关性,联合检测可能对胃癌的诊治具有指导价值。
基金supported by the National Natural Science Foundation of China (71991484,42271471,72088101,and 41830645)Danish Agency for Higher Education and Science (International Network Project,0192-00056B)the Fundamental Research Funds for the Central Universities (Peking University).
文摘The patterns of material accumulation in buildings and infrastructure accompanied by rapid urbanization offer an important,yet hitherto largely missing stock perspective for facilitating urban system engineering and informing urban resources,waste,and climate strategies.However,our existing knowledge on the patterns of built environment stocks across and particularly within cities is limited,largely owing to the lack of sufficient high spatial resolution data.This study leveraged multi-source big geodata,machine learning,and bottom-up stock accounting to characterize the built environment stocks of 50 cities in China at 500 m fine-grained levels.The per capita built environment stock of many cities(261 tonnes per capita on average)is close to that in western cities,despite considerable disparities across cities owing to their varying socioeconomic,geomorphology,and urban form characteristics.This is mainly owing to the construction boom and the building and infrastructure-driven economy of China in the past decades.China’s urban expansion tends to be more“vertical”(with high-rise buildings)than“horizontal”(with expanded road networks).It trades skylines for space,and reflects a concentration-dispersion-concentration pathway for spatialized built environment stocks development within cities in China.These results shed light on future urbanization in developing cities,inform spatial planning,and support circular and low-carbon transitions in cities.
