目的评价多层螺旋计算机断层扫描(computed tomography,CT)血管造影(multislice computed tomography angiography,MSCTA)检测冠状动脉易损斑块的可靠性,建立急性冠脉综合征积分(score system of acute coronary syndromes,SACS),用于...目的评价多层螺旋计算机断层扫描(computed tomography,CT)血管造影(multislice computed tomography angiography,MSCTA)检测冠状动脉易损斑块的可靠性,建立急性冠脉综合征积分(score system of acute coronary syndromes,SACS),用于评估冠状动脉粥样硬化性心脏病(冠心病)患者危险分层。方法研究20例非急性冠脉综合征及41例急性冠脉综合征且冠状动脉MSCTA发现斑块的患者,比较两组斑块CT值、重构指数(RI)等指标,进而构建急性冠脉综合征发病风险预测模型。结果两组病变血管99支,可分析斑块117个,非急性冠脉综合征组36个,以钙化斑块为主(88.9%,32/36);急性冠脉综合征组81个,以脂质斑块为主(37.0%,30/81)。两组正性重构比例比较,差异有统计学意义(61.1%vs.32.1%,P<0.01);负性重构比例比较,差异有统计学意义(25.0%vs.19.8%,P<0.01)。由RI建立SACS,所得模型为:SACS=0.003PA+2.255RI-4.22,预测准确率为76.9%(P<0.01),受试者工作曲线下面积为0.815(P<0.01)。结论急性冠脉综合征患者冠状动脉斑块多为脂质斑块,以正性重构为主,SACS对急性冠脉综合征发病具有较高的预测价值,有助于临床指导冠心病危险分层及早期干预。展开更多
Characteristics of the Internet traffic data flow are studied based on the chaos theory. A phase space that is isometric with the network dynamic system is reconstructed by using the single variable time series of a n...Characteristics of the Internet traffic data flow are studied based on the chaos theory. A phase space that is isometric with the network dynamic system is reconstructed by using the single variable time series of a network flow. Some parameters, such as the correlative dimension and the Lyapunov exponent are calculated, and the chaos characteristic is proved to exist in Internet traffic data flows. A neural network model is construct- ed based on radial basis function （RBF） to forecast actual Internet traffic data flow. Simulation results show that, compared with other forecasts of the forward-feedback neural network, the forecast of the RBF neural network based on the chaos theory has faster learning capacity and higher forecasting accuracy.展开更多
A study was conducted to determine the characters of soil structure in different water and soil conservation forests in Keshan County,northwest of Heilongjiang Province,China.The soil bulk density,the ratio of non-cap...A study was conducted to determine the characters of soil structure in different water and soil conservation forests in Keshan County,northwest of Heilongjiang Province,China.The soil bulk density,the ratio of non-capillary porosity and capillary porosity（NCP/CP）,and the generalized soil structure index（GSSI） were measured for Fraxinus mandshurica,Larix gmelini,Pinus sylvestris var.mongolica,and Picea koraiensis plantations as well as the abandoned land（as control） adjacent to the forests in typical black soil region.Results show that at soil depth of 0–30cm,the soil bulk density of F.mandshurica forest and L.gmelini forest was lower than that of P.sylvestris var.mongolica forest and P.koraiensis forest,with the relative decrease of 8.04%–11.01%.The soil bulk density of L.gmelini forest was significantly different from that of the P.sylvestris var.mongolica forest and P.koraiensis forest.The NCP/CP values of the four types of plantations were all higher（59.75%–128.82% relatively） than that of abandoned land（p〈0.05）,indicating that the soil aeration and permeability under forest were enhanced,especially under L.gmelini forest.GSSI values of the four types of forests were also relatively higher（2.98%–4.36%） than abandoned land（p〈0.05）,indicating that those soil and water conservation forests,especially the F.mandshurica forest and P.koraiensis forest,can promote soil condition to approximate ideal soil structure.The result of this study can provide theoretical basis for scientifically evaluating the effects of vegetation restoration on soil quality in typical black soil region.展开更多
文摘目的评价多层螺旋计算机断层扫描(computed tomography,CT)血管造影(multislice computed tomography angiography,MSCTA)检测冠状动脉易损斑块的可靠性,建立急性冠脉综合征积分(score system of acute coronary syndromes,SACS),用于评估冠状动脉粥样硬化性心脏病(冠心病)患者危险分层。方法研究20例非急性冠脉综合征及41例急性冠脉综合征且冠状动脉MSCTA发现斑块的患者,比较两组斑块CT值、重构指数(RI)等指标,进而构建急性冠脉综合征发病风险预测模型。结果两组病变血管99支,可分析斑块117个,非急性冠脉综合征组36个,以钙化斑块为主(88.9%,32/36);急性冠脉综合征组81个,以脂质斑块为主(37.0%,30/81)。两组正性重构比例比较,差异有统计学意义(61.1%vs.32.1%,P<0.01);负性重构比例比较,差异有统计学意义(25.0%vs.19.8%,P<0.01)。由RI建立SACS,所得模型为:SACS=0.003PA+2.255RI-4.22,预测准确率为76.9%(P<0.01),受试者工作曲线下面积为0.815(P<0.01)。结论急性冠脉综合征患者冠状动脉斑块多为脂质斑块,以正性重构为主,SACS对急性冠脉综合征发病具有较高的预测价值,有助于临床指导冠心病危险分层及早期干预。
文摘Characteristics of the Internet traffic data flow are studied based on the chaos theory. A phase space that is isometric with the network dynamic system is reconstructed by using the single variable time series of a network flow. Some parameters, such as the correlative dimension and the Lyapunov exponent are calculated, and the chaos characteristic is proved to exist in Internet traffic data flows. A neural network model is construct- ed based on radial basis function （RBF） to forecast actual Internet traffic data flow. Simulation results show that, compared with other forecasts of the forward-feedback neural network, the forecast of the RBF neural network based on the chaos theory has faster learning capacity and higher forecasting accuracy.
基金supported by National Natural Science Foundation of China (No 30872068)the Science and Technology Key Scientific Project of Heilongjiang Province (GA06B302-3)Fund of Thesis for Post Graduated Student of NEFU(GRAM09)
文摘A study was conducted to determine the characters of soil structure in different water and soil conservation forests in Keshan County,northwest of Heilongjiang Province,China.The soil bulk density,the ratio of non-capillary porosity and capillary porosity（NCP/CP）,and the generalized soil structure index（GSSI） were measured for Fraxinus mandshurica,Larix gmelini,Pinus sylvestris var.mongolica,and Picea koraiensis plantations as well as the abandoned land（as control） adjacent to the forests in typical black soil region.Results show that at soil depth of 0–30cm,the soil bulk density of F.mandshurica forest and L.gmelini forest was lower than that of P.sylvestris var.mongolica forest and P.koraiensis forest,with the relative decrease of 8.04%–11.01%.The soil bulk density of L.gmelini forest was significantly different from that of the P.sylvestris var.mongolica forest and P.koraiensis forest.The NCP/CP values of the four types of plantations were all higher（59.75%–128.82% relatively） than that of abandoned land（p〈0.05）,indicating that the soil aeration and permeability under forest were enhanced,especially under L.gmelini forest.GSSI values of the four types of forests were also relatively higher（2.98%–4.36%） than abandoned land（p〈0.05）,indicating that those soil and water conservation forests,especially the F.mandshurica forest and P.koraiensis forest,can promote soil condition to approximate ideal soil structure.The result of this study can provide theoretical basis for scientifically evaluating the effects of vegetation restoration on soil quality in typical black soil region.
