电力电子设备在功率变换过程中,同时具备发送信息的能力。功率/数据双载波调制技术通过在功率控制环输出的基准上叠加信号载波,同时实现功率变换与信息发送功能。该方法采用独立的通信载波,不需要额外的通信控制器和耦合电路,具有信号...电力电子设备在功率变换过程中,同时具备发送信息的能力。功率/数据双载波调制技术通过在功率控制环输出的基准上叠加信号载波,同时实现功率变换与信息发送功能。该方法采用独立的通信载波,不需要额外的通信控制器和耦合电路,具有信号强度可调、传输距离远和实施成本低等优点。为提高通信速率,采用正交频分复用(orthogonal frequency division multiplexing,OFDM)技术进行信号调制。首先介绍了基于OFDM的功率/数据双载波调制的基本原理;然后对直流微网系统进行建模,分析了信道的传递函数,讨论了数据接收方案、通信帧的设计方法和峰均功率比(peak-to-average power ratio,PAPR)抑制问题,并选用了一种适用于功率/数据双载波调制的低峰均功率比设计方法;最后搭建了1个2kW的直流微网平台,应用所提技术在2台变换器间实现了9.6kb/s速率的通信,验证了该技术的可行性。展开更多
目的目前的研究已经证实骨质疏松症与牙周炎之间存在一定关联,但是二者之间的因果关联尚不清楚。同时,血清25-羟基维生素D状态也可改变牙周炎的发生风险。因此,本研究进行了孟德尔随机化(Mendelian randomization,MR)分析探究骨密度(Bon...目的目前的研究已经证实骨质疏松症与牙周炎之间存在一定关联,但是二者之间的因果关联尚不清楚。同时,血清25-羟基维生素D状态也可改变牙周炎的发生风险。因此,本研究进行了孟德尔随机化(Mendelian randomization,MR)分析探究骨密度(Bone mineral density,BMD)与牙周炎之间是否存在因果关联,以及是否由血清25-羟基维生素D介导。方法本研究采用骨密度、血清25-羟基维生素D以及牙周炎的全基因组关联研究(Genome wide association studies,GWAS)的汇总统计数据进行了两样本孟德尔随机化研究,以探究骨密度水平和牙周炎风险之间是否存在因果关联,以及是否由血清25-羟基维生素D介导。同时,本研究进行了敏感性分析,以确保结果的稳健性。结果在IVW固定效应模型下,遗传预测的骨密度与牙周炎风险之间存在因果关联并呈负相关(OR=0.921,95%CI:0.855-0.991,P=2.71e-02),最大似然法(OR=0.921,95%CI:0.856-0.991,P=2.84e-02)。对骨密度和血清25-羟基维生素D水平进行两样本孟德尔随机化研究,加权中位数结果显示,骨密度与血清25-羟基维生素D水平相关(OR=0.986,95%CI:0.973-0.999,P=3.44e-02),惩罚加权中位数分析(OR=0.983,95%CI:0.970-0.997,P=1.72e-02)。对血清25-羟基维生素D水平和牙周炎进行两样本孟德尔随机化研究,MR-Egger分析结果显示,血清25-羟基维生素D水平与牙周炎风险相关(OR=1.203,95%CI:1.012-1.430,P=3.95e-02)。结论MR分析研究显示,骨密度与牙周炎之间存在因果关联,并且可能由血清25-羟基维生素D介导。展开更多
在经济下行和违约规模逐步增加的环境下,投资者对市场的尾部风险比较敏感。借鉴Fama and MacBeth(1973)的因子分析方法,我们在截面维度和时间序列维度验证了债券收益与尾部风险的关系,发现尾部风险每增加一个标准差,债券年化超额收益约...在经济下行和违约规模逐步增加的环境下,投资者对市场的尾部风险比较敏感。借鉴Fama and MacBeth(1973)的因子分析方法,我们在截面维度和时间序列维度验证了债券收益与尾部风险的关系,发现尾部风险每增加一个标准差,债券年化超额收益约增加4.15%。通过做多高尾部风险组债券和做空低尾部风险组债券得到的投资组合平均有月度0.58%的超额收益。实证结果验证了市场对尾部风险的定价机制——投资者面对资产分布的不确定时对损失更为厌恶和用尾部风险历史数据分析违约风险的概率。展开更多
AIM： To investigate the effects of p57^kip2, cyclinE protein and proliferating cell nuclear antigen （PCNA） on occurrence and progression of human pancreatic cancer. METHODS： The expression of p57^kip2, cyclinE pro...AIM： To investigate the effects of p57^kip2, cyclinE protein and proliferating cell nuclear antigen （PCNA） on occurrence and progression of human pancreatic cancer. METHODS： The expression of p57^kip2, cyclinE protein and PCNA in tumor tissues and adjacent tissues from 32 patients with pancreatic cancer was detected by SP immunohistochemical technique. RESULTS： The positive expression rate of p57^kip2 protein in tumor tissues was 46.9%, which was lower than that in adjacent pancreatic tissues （χ^2 = 5.317, P〈0.05）. p57^kip2 protein positive expression remarkably correlated with tumor cell differentiation （P〈0.05）, but not with lymph node metastasis （P〉0.05）. The positive expression rate of cyclinE protein in tumor tissues was 68.8%, which was higher than that in adjacent pancreatic tissues （χ^2 = 4.063, P〈0.05）. CyclinE protein positive expression significantly correlated with tumor cell differentiation and lymph node metastasis （P〈0.05）. The positive expression rate of PCNA in the tumor tissues was 71.9%, which was higher than that in adjacent pancreatic tissues （χ^2 = 5.189, P〈0.05）. PCNA positive expression remarkably correlated with tumor cell differentiation and lymph node metastasis （P〈0.05）. CONCLUSION： The decreased expression of p57^kip2 and/or overexpression of cyclinE protein and PCNA may contribute to the occurrence and progression of pancreatic cancer. p57^kip2, cyclinE protein, and PCNA play an important role in occurrence and progression of pancreatic cancer.展开更多
Dental pulp stem cells are dental pulp-derived mesenchymal stem cells that originate from the neural crest.They exhibit greater potential for the treatment of nervous system diseases than other types of stem cells bec...Dental pulp stem cells are dental pulp-derived mesenchymal stem cells that originate from the neural crest.They exhibit greater potential for the treatment of nervous system diseases than other types of stem cells because of their neurogenic differentiation capability and their ability to secrete multiple neurotrophic factors.Few studies have reported Alzheimer’s disease treatment using dental pulp stem cells.Rat models of Alzheimer’s disease were established by injecting amyloid-β1–42 into the hippocampus.Fourteen days later,5×106 dental pulp stem cells were injected into the hippocampus.Immunohistochemistry and western blot assays showed that dental pulp stem cell transplantation increased the expression of neuron-related doublecortin,NeuN,and neurofilament 200 in the hippocampus,while the expression of amyloid-βwas decreased.Moreover,cognitive and behavioral abilities were improved.These findings indicate that dental pulp stem cell transplantation in rats can improve cognitive function by regulating the secretion of neuron-related proteins,which indicates a potential therapeutic effect for Alzheimer’s disease.This study was approved by the Animal Ethics Committee of Harbin Medical University,China(approval No.KY2017-132)on February 21,2017.展开更多
Dental pulp stem cells are a type of adult stem cells with strong proliferative ability and multi-differentiation potential. There are no studies on treatment of vascular dementia with dental pulp stem cells. In the p...Dental pulp stem cells are a type of adult stem cells with strong proliferative ability and multi-differentiation potential. There are no studies on treatment of vascular dementia with dental pulp stem cells. In the present study, rat models of vascular dementia were established by two-vessel occlusion, and 30 days later, rats were injected with 2 × 10^(7) dental pulp stem cells via the tail vein. At 70 days after vascular dementia induction, dental pulp stem cells had migrated to the brain tissue of rat vascular dementia models and differentiated into neuronlike cells. At the same time, doublecortin, neurofilament 200, and Neu N m RNA and protein expression levels in the brain tissue were increased, and glial fibrillary acidic protein m RNA and protein expression levels were decreased. Behavioral testing also revealed that dental pulp stem cell transplantation improved the cognitive function of rat vascular dementia models. These findings suggest that dental pulp stem cell transplantation is effective in treating vascular dementia possibly through a paracrine mechanism. The study was approved by the Animal Ethics Committee of Harbin Medical University(approval No. KY2017-132) in 2017.展开更多
文摘电力电子设备在功率变换过程中,同时具备发送信息的能力。功率/数据双载波调制技术通过在功率控制环输出的基准上叠加信号载波,同时实现功率变换与信息发送功能。该方法采用独立的通信载波,不需要额外的通信控制器和耦合电路,具有信号强度可调、传输距离远和实施成本低等优点。为提高通信速率,采用正交频分复用(orthogonal frequency division multiplexing,OFDM)技术进行信号调制。首先介绍了基于OFDM的功率/数据双载波调制的基本原理;然后对直流微网系统进行建模,分析了信道的传递函数,讨论了数据接收方案、通信帧的设计方法和峰均功率比(peak-to-average power ratio,PAPR)抑制问题,并选用了一种适用于功率/数据双载波调制的低峰均功率比设计方法;最后搭建了1个2kW的直流微网平台,应用所提技术在2台变换器间实现了9.6kb/s速率的通信,验证了该技术的可行性。
文摘目的目前的研究已经证实骨质疏松症与牙周炎之间存在一定关联,但是二者之间的因果关联尚不清楚。同时,血清25-羟基维生素D状态也可改变牙周炎的发生风险。因此,本研究进行了孟德尔随机化(Mendelian randomization,MR)分析探究骨密度(Bone mineral density,BMD)与牙周炎之间是否存在因果关联,以及是否由血清25-羟基维生素D介导。方法本研究采用骨密度、血清25-羟基维生素D以及牙周炎的全基因组关联研究(Genome wide association studies,GWAS)的汇总统计数据进行了两样本孟德尔随机化研究,以探究骨密度水平和牙周炎风险之间是否存在因果关联,以及是否由血清25-羟基维生素D介导。同时,本研究进行了敏感性分析,以确保结果的稳健性。结果在IVW固定效应模型下,遗传预测的骨密度与牙周炎风险之间存在因果关联并呈负相关(OR=0.921,95%CI:0.855-0.991,P=2.71e-02),最大似然法(OR=0.921,95%CI:0.856-0.991,P=2.84e-02)。对骨密度和血清25-羟基维生素D水平进行两样本孟德尔随机化研究,加权中位数结果显示,骨密度与血清25-羟基维生素D水平相关(OR=0.986,95%CI:0.973-0.999,P=3.44e-02),惩罚加权中位数分析(OR=0.983,95%CI:0.970-0.997,P=1.72e-02)。对血清25-羟基维生素D水平和牙周炎进行两样本孟德尔随机化研究,MR-Egger分析结果显示,血清25-羟基维生素D水平与牙周炎风险相关(OR=1.203,95%CI:1.012-1.430,P=3.95e-02)。结论MR分析研究显示,骨密度与牙周炎之间存在因果关联,并且可能由血清25-羟基维生素D介导。
文摘在经济下行和违约规模逐步增加的环境下,投资者对市场的尾部风险比较敏感。借鉴Fama and MacBeth(1973)的因子分析方法,我们在截面维度和时间序列维度验证了债券收益与尾部风险的关系,发现尾部风险每增加一个标准差,债券年化超额收益约增加4.15%。通过做多高尾部风险组债券和做空低尾部风险组债券得到的投资组合平均有月度0.58%的超额收益。实证结果验证了市场对尾部风险的定价机制——投资者面对资产分布的不确定时对损失更为厌恶和用尾部风险历史数据分析违约风险的概率。
文摘AIM： To investigate the effects of p57^kip2, cyclinE protein and proliferating cell nuclear antigen （PCNA） on occurrence and progression of human pancreatic cancer. METHODS： The expression of p57^kip2, cyclinE protein and PCNA in tumor tissues and adjacent tissues from 32 patients with pancreatic cancer was detected by SP immunohistochemical technique. RESULTS： The positive expression rate of p57^kip2 protein in tumor tissues was 46.9%, which was lower than that in adjacent pancreatic tissues （χ^2 = 5.317, P〈0.05）. p57^kip2 protein positive expression remarkably correlated with tumor cell differentiation （P〈0.05）, but not with lymph node metastasis （P〉0.05）. The positive expression rate of cyclinE protein in tumor tissues was 68.8%, which was higher than that in adjacent pancreatic tissues （χ^2 = 4.063, P〈0.05）. CyclinE protein positive expression significantly correlated with tumor cell differentiation and lymph node metastasis （P〈0.05）. The positive expression rate of PCNA in the tumor tissues was 71.9%, which was higher than that in adjacent pancreatic tissues （χ^2 = 5.189, P〈0.05）. PCNA positive expression remarkably correlated with tumor cell differentiation and lymph node metastasis （P〈0.05）. CONCLUSION： The decreased expression of p57^kip2 and/or overexpression of cyclinE protein and PCNA may contribute to the occurrence and progression of pancreatic cancer. p57^kip2, cyclinE protein, and PCNA play an important role in occurrence and progression of pancreatic cancer.
基金This study was supported by Yu Weihan Fund for Distinguished Young Scholars of Harbin Medical University of China,No.002000013(to XMZ).
文摘Dental pulp stem cells are dental pulp-derived mesenchymal stem cells that originate from the neural crest.They exhibit greater potential for the treatment of nervous system diseases than other types of stem cells because of their neurogenic differentiation capability and their ability to secrete multiple neurotrophic factors.Few studies have reported Alzheimer’s disease treatment using dental pulp stem cells.Rat models of Alzheimer’s disease were established by injecting amyloid-β1–42 into the hippocampus.Fourteen days later,5×106 dental pulp stem cells were injected into the hippocampus.Immunohistochemistry and western blot assays showed that dental pulp stem cell transplantation increased the expression of neuron-related doublecortin,NeuN,and neurofilament 200 in the hippocampus,while the expression of amyloid-βwas decreased.Moreover,cognitive and behavioral abilities were improved.These findings indicate that dental pulp stem cell transplantation in rats can improve cognitive function by regulating the secretion of neuron-related proteins,which indicates a potential therapeutic effect for Alzheimer’s disease.This study was approved by the Animal Ethics Committee of Harbin Medical University,China(approval No.KY2017-132)on February 21,2017.
基金supported by Yu Weihan Fund for Distinguished Young Scholars of Harbin Medical University of China,No. 002000013 (to XMZ)。
文摘Dental pulp stem cells are a type of adult stem cells with strong proliferative ability and multi-differentiation potential. There are no studies on treatment of vascular dementia with dental pulp stem cells. In the present study, rat models of vascular dementia were established by two-vessel occlusion, and 30 days later, rats were injected with 2 × 10^(7) dental pulp stem cells via the tail vein. At 70 days after vascular dementia induction, dental pulp stem cells had migrated to the brain tissue of rat vascular dementia models and differentiated into neuronlike cells. At the same time, doublecortin, neurofilament 200, and Neu N m RNA and protein expression levels in the brain tissue were increased, and glial fibrillary acidic protein m RNA and protein expression levels were decreased. Behavioral testing also revealed that dental pulp stem cell transplantation improved the cognitive function of rat vascular dementia models. These findings suggest that dental pulp stem cell transplantation is effective in treating vascular dementia possibly through a paracrine mechanism. The study was approved by the Animal Ethics Committee of Harbin Medical University(approval No. KY2017-132) in 2017.
