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
The soil hardness, soil water content and soil bulk density along the trails of six scenic spots in the Zhangjiajie World Geopark were measured and analyzed, and the integrated effects of tourism trampling on soils we...The soil hardness, soil water content and soil bulk density along the trails of six scenic spots in the Zhangjiajie World Geopark were measured and analyzed, and the integrated effects of tourism trampling on soils were evaluated for each scenic spots by calculating its soil impact indexes （SII） in the park. The results indicated that visitors＇ activities caused a serious influence on the soil in the park, especially in the two most used scenic spots-- Yellowstone Village and Gold Whip Stream. The impact of tourism on soil mainly occurred within 3 m along the trails. The impact shapes are classified into six type as single-sided node type, double-sided node type, cross node type, single-sided linkage type, double-sided linkage type and short-cut linkage type. Of six types of impact shapes, the single-sided node type and double-sided type were dominant. The average water contents of soil for six scenic spots at sample areas of 1 m, 2 m and 3 m from trial is 36.6%, 24.5% and 2.2% lower than that of the control area, respectively. The average soil hardness for six scenic spots at 1m, 2 m, and 3m from the trails tramped increased 167.9%, and 122.2%, and 15.8%, respectively, compared with the control area. Soil bulk density increased 26.5% at 1 m and 20.9% at 2 m from the trails. The main countermeasures for reducing the range and extent of tourism impact on soil are discussed.展开更多
Objective To assess the prevalence of and risk factors for postprandial hypotension （PPH） among old and very old Chinese men. Methods The study included 349 Chinese men aged 65 and older, grouped into two age catego...Objective To assess the prevalence of and risk factors for postprandial hypotension （PPH） among old and very old Chinese men. Methods The study included 349 Chinese men aged 65 and older, grouped into two age categories： group 1 （old） included 163 men aged 65 to 80 years; group 2 （very old） included 186 men aged over 80 years. Blood pressure changes after meals were assessed every 15 min by ambulatory blood pressure monitoring. Symptoms after meal ingestion and after standing up and changes in the baseline condition relative to blood pressure changes were observed continuously. Additional baseline data included body mass index, medical history, and medication use Results The prevalence of PPH was 59.3% overall and was significantly higher in group 2 than group 1 （63.4% vs. 54.6%, P 〈 0.05）. In group 2, the prevalence of PPH after breakfast （33.8%） and lunch （32.1%） were higher than that after supper （20.9%）, P 〈 0.05. Hypertension and age were significant risk factors for PPH （OR = 2.188, 95% CI： 1.134-4.223, P = 0.02; OR = 1.86, 95% CI： 1.112-3.11, P = 0.018, respectively）. In contrast, acarbose use was protective against PPH （OR = 0.4, 95% CI： 0.189-0.847, P = 0.017）. The decrease in blood pres- sure during PPH was 20-40 mmHg and the maximum was 90 mmHg. PPH usually occurred at 30-60 min after a meal and lasted 30-120 rnin. Conclusions These findings demonstrate that the prevalence of PPH in men aged over 80 years is significantly higher than those in men aged 65 to 80 years, and the blood pressure decline is also higher for men aged over 80 years. In addition, hypertension and age were main risk factors for PPH in the older men, which suggest that preventing and treating PPH is worthwhile.展开更多
Objective： To study the influences of different time intervals between loop electrosurgical excision （LEEP） and abdominal hysterectomy or radical hysterectomy on postoperative complications. Methods： Sixty-eight p...Objective： To study the influences of different time intervals between loop electrosurgical excision （LEEP） and abdominal hysterectomy or radical hysterectomy on postoperative complications. Methods： Sixty-eight patients, who received subsequent abdominal hysterectomy or radical hysterectomy after LEEP due to C1N III and cervical cancer （IA1, IA2 and IB1）, were included in the present study. The hospital and clinic records of these patients were reviewed. The patients were divided into three groups according to the time intervals between LEEP and hysterectomy or radical hysterectomy： group l（within 48 h）, group 2 （between 48 h to 6 weeks）, and group 3（〉 6 weeks ）.Results： General characteristics of patients, including the mean age, delivery history, BMI, menopausal status, clinical stage and HPV infection, were comparable between patients of different groups. There were no significant differences in the mean transfusion amount, posthysterectomy hospital stay or operation time between different groups. The frequencies and spectrum of complications were not significantly affected by the time interval between LEEP and hysterectomy or radical hysterectomy. Conclusion： It is concluded that whenever the LEEP is done, the operation including hysterectomy or radical hysterectomy can be conducted at any time as it is necessary for the patients.展开更多
Objective To investigate the prevalence of abnormity of blood lipid and associated factors in healthy population in Beijing. Methods Totally, 38 462 individuals who received health examination were enrolled in our stu...Objective To investigate the prevalence of abnormity of blood lipid and associated factors in healthy population in Beijing. Methods Totally, 38 462 individuals who received health examination were enrolled in our study. We divided them into eight groups according to their ages. The levels of serum total cholesterol, triglyceride, high density lipoprotein cholesterol, and low density lipoprotein cholesterol were tested, and the relationship of blood lipid abnormity with body mass index (BMI) and fasting blood glucose was analyzed. Results The incidences of hypercholesterolemia, hyperglyceridemia, low high-density lipoprotein cholesterolemia, and hyper low-density lipoprotein cholesterolemia presented increasing trend in this population. The incidence rate of abnormity of blood lipid in health examination population increased with BMI increase. The incidence of abnormity of blood lipid in overweight and obesity population was significantly higher than that in low weight and normal weight populations (P<0.05). Meanwhile, the trend of abnormal blood lipid incidence coincided with that of abnormal fasting blood glucose. Conclusions The prevalence of overweight, obesity, and abnormity of blood lipid in Beijing presents increasing trend. The incidence of abnormity of blood lipid increases with BMI increase, in coincidence with that of fasting blood glucose.展开更多
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.
基金This study was supported by the National Natural Science Foundation of China (NSFC30200040) and the Thousand-hundred-ten Talent Engineering project of Guangdong Province, P. R. China (03130401)
文摘The soil hardness, soil water content and soil bulk density along the trails of six scenic spots in the Zhangjiajie World Geopark were measured and analyzed, and the integrated effects of tourism trampling on soils were evaluated for each scenic spots by calculating its soil impact indexes （SII） in the park. The results indicated that visitors＇ activities caused a serious influence on the soil in the park, especially in the two most used scenic spots-- Yellowstone Village and Gold Whip Stream. The impact of tourism on soil mainly occurred within 3 m along the trails. The impact shapes are classified into six type as single-sided node type, double-sided node type, cross node type, single-sided linkage type, double-sided linkage type and short-cut linkage type. Of six types of impact shapes, the single-sided node type and double-sided type were dominant. The average water contents of soil for six scenic spots at sample areas of 1 m, 2 m and 3 m from trial is 36.6%, 24.5% and 2.2% lower than that of the control area, respectively. The average soil hardness for six scenic spots at 1m, 2 m, and 3m from the trails tramped increased 167.9%, and 122.2%, and 15.8%, respectively, compared with the control area. Soil bulk density increased 26.5% at 1 m and 20.9% at 2 m from the trails. The main countermeasures for reducing the range and extent of tourism impact on soil are discussed.
文摘Objective To assess the prevalence of and risk factors for postprandial hypotension （PPH） among old and very old Chinese men. Methods The study included 349 Chinese men aged 65 and older, grouped into two age categories： group 1 （old） included 163 men aged 65 to 80 years; group 2 （very old） included 186 men aged over 80 years. Blood pressure changes after meals were assessed every 15 min by ambulatory blood pressure monitoring. Symptoms after meal ingestion and after standing up and changes in the baseline condition relative to blood pressure changes were observed continuously. Additional baseline data included body mass index, medical history, and medication use Results The prevalence of PPH was 59.3% overall and was significantly higher in group 2 than group 1 （63.4% vs. 54.6%, P 〈 0.05）. In group 2, the prevalence of PPH after breakfast （33.8%） and lunch （32.1%） were higher than that after supper （20.9%）, P 〈 0.05. Hypertension and age were significant risk factors for PPH （OR = 2.188, 95% CI： 1.134-4.223, P = 0.02; OR = 1.86, 95% CI： 1.112-3.11, P = 0.018, respectively）. In contrast, acarbose use was protective against PPH （OR = 0.4, 95% CI： 0.189-0.847, P = 0.017）. The decrease in blood pres- sure during PPH was 20-40 mmHg and the maximum was 90 mmHg. PPH usually occurred at 30-60 min after a meal and lasted 30-120 rnin. Conclusions These findings demonstrate that the prevalence of PPH in men aged over 80 years is significantly higher than those in men aged 65 to 80 years, and the blood pressure decline is also higher for men aged over 80 years. In addition, hypertension and age were main risk factors for PPH in the older men, which suggest that preventing and treating PPH is worthwhile.
文摘Objective： To study the influences of different time intervals between loop electrosurgical excision （LEEP） and abdominal hysterectomy or radical hysterectomy on postoperative complications. Methods： Sixty-eight patients, who received subsequent abdominal hysterectomy or radical hysterectomy after LEEP due to C1N III and cervical cancer （IA1, IA2 and IB1）, were included in the present study. The hospital and clinic records of these patients were reviewed. The patients were divided into three groups according to the time intervals between LEEP and hysterectomy or radical hysterectomy： group l（within 48 h）, group 2 （between 48 h to 6 weeks）, and group 3（〉 6 weeks ）.Results： General characteristics of patients, including the mean age, delivery history, BMI, menopausal status, clinical stage and HPV infection, were comparable between patients of different groups. There were no significant differences in the mean transfusion amount, posthysterectomy hospital stay or operation time between different groups. The frequencies and spectrum of complications were not significantly affected by the time interval between LEEP and hysterectomy or radical hysterectomy. Conclusion： It is concluded that whenever the LEEP is done, the operation including hysterectomy or radical hysterectomy can be conducted at any time as it is necessary for the patients.
基金Sponsored by grant of Young Scientist of PUMC Hospital (200577A)
文摘Objective To investigate the prevalence of abnormity of blood lipid and associated factors in healthy population in Beijing. Methods Totally, 38 462 individuals who received health examination were enrolled in our study. We divided them into eight groups according to their ages. The levels of serum total cholesterol, triglyceride, high density lipoprotein cholesterol, and low density lipoprotein cholesterol were tested, and the relationship of blood lipid abnormity with body mass index (BMI) and fasting blood glucose was analyzed. Results The incidences of hypercholesterolemia, hyperglyceridemia, low high-density lipoprotein cholesterolemia, and hyper low-density lipoprotein cholesterolemia presented increasing trend in this population. The incidence rate of abnormity of blood lipid in health examination population increased with BMI increase. The incidence of abnormity of blood lipid in overweight and obesity population was significantly higher than that in low weight and normal weight populations (P<0.05). Meanwhile, the trend of abnormal blood lipid incidence coincided with that of abnormal fasting blood glucose. Conclusions The prevalence of overweight, obesity, and abnormity of blood lipid in Beijing presents increasing trend. The incidence of abnormity of blood lipid increases with BMI increase, in coincidence with that of fasting blood glucose.
