Guanting Reservoir, one of the drinking water supply sources of Beijing, suffers from water eutrophication. It is mainly supplied by Guishui River. Thus, to investigate the reasons of phosphorus （P） loss and improve...Guanting Reservoir, one of the drinking water supply sources of Beijing, suffers from water eutrophication. It is mainly supplied by Guishui River. Thus, to investigate the reasons of phosphorus （P） loss and improve the P management strategies in Guishui River watershed are important for the safety of drinking water in this region. In this study, a Revised Field P Ranking Scheme （PRS） was developed to reflect the field vulnerability of P loss at the field scale based on the Field PRS. In this new scheme, six factors are included, and each one was assigned a relative weight and a determination method. The affecting factors were classified into transport factors and source factors, and, the standards of environmental quality on surface water and soil erosion classification and degradation of the China were used in this scheme. By the new scheme, thirty-four fields in the Guishui River were categorized as ＂low＂, ＂medium＂ or ＂high＂ potential for P loss into the runoff. The results showed that the P loss risks of orchard and vegetable fields were higher than that of corn and soybean fields. The source factors were the main factors to affect P loss from the study area. In the study area, controlling P input and improving P usage efficiency are critical to decrease P loss. Based on the results, it was suggested that more attention should be paid on the fields of vegetable and orchard since they have extremely high usage rate of P and high soil test of P. Compared with P surplus by field measurements, the Revised Field PRS was more suitable for reflecting the characteristics of fields, and had higher potential capacity to identify critical source areas of P loss than PRS.展开更多
Many unique properties of complex networks result from heterogeneity. The measure and analysis of heterogeneity are important and desirable to the research of the properties and functions of complex networks. In this ...Many unique properties of complex networks result from heterogeneity. The measure and analysis of heterogeneity are important and desirable to the research of the properties and functions of complex networks. In this paper, the rank distribution is proposed as a new statistic feature of complex networks. Based on the rank distribution, a novel measure of the heterogeneity called a normalized entropy of rank distribution （NERD） is proposed. The NERD accords with the normal meaning of heterogeneity within the context of complex networks compared with conventional measures. The heterogeneity of scale-free networks is studied using the NERD. It is shown that scale-free networks become more heterogeneous as the scaling exponent decreases and the NERD of scale-free networks is independent of the number of vertices, which indicates that the NERD is a suitable and effective measure of heterogeneity for networks with different sizes.展开更多
In this paper we study the perturbation bound of the projection ( W A ) ( W A )+,where both the matrices A and W are given with W positive diagonal and severely stiff.When the perturbed matrix (A)= A + δA satisfy sev...In this paper we study the perturbation bound of the projection ( W A ) ( W A )+,where both the matrices A and W are given with W positive diagonal and severely stiff.When the perturbed matrix (A)= A + δA satisfy several row rank preserving conditions,we derive a new perturbation bound of the projection.展开更多
We consider an Iterated-Subspace Minimization(ISM) method for solving large-scale unconstrained minimization problems. At each major iteration of the method,a two-dimensional manifold, the iterated subspace, is constr...We consider an Iterated-Subspace Minimization(ISM) method for solving large-scale unconstrained minimization problems. At each major iteration of the method,a two-dimensional manifold, the iterated subspace, is constructed and an approximate minimizer of the objective function in this manifold then determined, and a symmetric rank-one updating is used to solve the inner minimization problem.展开更多
Ba<span style="font-family:Verdana;">sed on the urban resident population statistics from 2005 to 2018, thi</span><span style="font-family:Verdana;">s paper analyzes the distribut...Ba<span style="font-family:Verdana;">sed on the urban resident population statistics from 2005 to 2018, thi</span><span style="font-family:Verdana;">s paper analyzes the distribution and evolution of city scale in China by screening city samples according to the threshold criteria and using empirical research methods such as the City Primacy Index, the Rank-Scale Rule, the Gini coefficient of city scale, Kernel Density Estimation and Markov transfer matrix. The results show that: the most populous city in China has obvious advantages. The population distribution is concentrated in high order cities and in accordance with the law of order</span><span style="font-family:Verdana;">-</span><span style="font-family:""><span style="font-family:Verdana;">scale;the economic scale of cities is in a concentrated state, the gap between the economic development levels of different types of cities is large, and the megacities are more attractive, which to a certain extent limit the development of the scale of the rest of the cities;th</span><span style="font-family:Verdana;">e number of China’s city population is increasing, however, the ga</span><span style="font-family:Verdana;">p between the</span></span><span style="font-family:""> </span><span style="font-family:Verdana;">population scale of other cities and the most populous city continues to be large, and the structure of city population scale is not reasonable enough;megacities and megalopolises keep their original scale levels unchanged to a large extent, and the scale transition between the two types of cities is rather difficult. Finally, based on the explanatory framework of the dynamics of city scale evolution, policy recommendations are proposed to promote a more balanced distribution of city scale.</span>展开更多
Introduction: The Liebowitz Social Anxiety Scale (LSAS), used to assess the severity of social anxiety disorder (SAD), requires considerable effort and time to complete. The aims of this study were: 1) to investigate ...Introduction: The Liebowitz Social Anxiety Scale (LSAS), used to assess the severity of social anxiety disorder (SAD), requires considerable effort and time to complete. The aims of this study were: 1) to investigate whether a visual analogue scale (VAS) could be linear with the LSAS and substitute for the LSAS, 2) to relate such a VAS instrument to patient demographics. Methods: Fifty SAD patients were assessed using the LSAS and VAS instruments completed by both patients and doctors at the same session. We then drew distributions and calculated the Spearman’s ρ and κ coefficient values (divided at the median for each scale) between patient and doctor assessments. Next, each pair among the scores for the LSAS, the patient VAS and the doctor VAS was compared using Wilcoxon rank sum tests according to patient life profile data. Results: Scatter plots of pairs of scores were obtained. Spearman’s ρ was 0.661 between the LSAS and the patient VAS, 0.461 between the LSAS and the doctor VAS, and 0.494 between VAS scores of patients and doctors. The κ coefficients were 0.501 between the LSAS and patient VAS, 0.251 between the LSAS and doctor VAS, and 0.425 between patient VAS and doctor VAS (for all six, p < 0.001). The Wilcoxon rank sum tests indicated a significant difference between the groups with/ without “employment” (LSAS, patient/doctor VAS), with/without “graduation from junior college/university” (doctor VAS) (p < 0.05) and with/without marital history (the age of first consultation) (p < 0.01). Conclusions: A patient VAS may substitute for the LSAS and offer the versatility necessary to capture patient states and life profiles.展开更多
基金Project supported by the National Basic Research Program of China(No.2005CB121107)the Innovation Research Group of National Basic Research Program of China(No.2005).
文摘Guanting Reservoir, one of the drinking water supply sources of Beijing, suffers from water eutrophication. It is mainly supplied by Guishui River. Thus, to investigate the reasons of phosphorus （P） loss and improve the P management strategies in Guishui River watershed are important for the safety of drinking water in this region. In this study, a Revised Field P Ranking Scheme （PRS） was developed to reflect the field vulnerability of P loss at the field scale based on the Field PRS. In this new scheme, six factors are included, and each one was assigned a relative weight and a determination method. The affecting factors were classified into transport factors and source factors, and, the standards of environmental quality on surface water and soil erosion classification and degradation of the China were used in this scheme. By the new scheme, thirty-four fields in the Guishui River were categorized as ＂low＂, ＂medium＂ or ＂high＂ potential for P loss into the runoff. The results showed that the P loss risks of orchard and vegetable fields were higher than that of corn and soybean fields. The source factors were the main factors to affect P loss from the study area. In the study area, controlling P input and improving P usage efficiency are critical to decrease P loss. Based on the results, it was suggested that more attention should be paid on the fields of vegetable and orchard since they have extremely high usage rate of P and high soil test of P. Compared with P surplus by field measurements, the Revised Field PRS was more suitable for reflecting the characteristics of fields, and had higher potential capacity to identify critical source areas of P loss than PRS.
基金Project supported by the National Natural Science Foundation of China （Grant No 70501032）.
文摘Many unique properties of complex networks result from heterogeneity. The measure and analysis of heterogeneity are important and desirable to the research of the properties and functions of complex networks. In this paper, the rank distribution is proposed as a new statistic feature of complex networks. Based on the rank distribution, a novel measure of the heterogeneity called a normalized entropy of rank distribution （NERD） is proposed. The NERD accords with the normal meaning of heterogeneity within the context of complex networks compared with conventional measures. The heterogeneity of scale-free networks is studied using the NERD. It is shown that scale-free networks become more heterogeneous as the scaling exponent decreases and the NERD of scale-free networks is independent of the number of vertices, which indicates that the NERD is a suitable and effective measure of heterogeneity for networks with different sizes.
文摘In this paper we study the perturbation bound of the projection ( W A ) ( W A )+,where both the matrices A and W are given with W positive diagonal and severely stiff.When the perturbed matrix (A)= A + δA satisfy several row rank preserving conditions,we derive a new perturbation bound of the projection.
文摘We consider an Iterated-Subspace Minimization(ISM) method for solving large-scale unconstrained minimization problems. At each major iteration of the method,a two-dimensional manifold, the iterated subspace, is constructed and an approximate minimizer of the objective function in this manifold then determined, and a symmetric rank-one updating is used to solve the inner minimization problem.
文摘Ba<span style="font-family:Verdana;">sed on the urban resident population statistics from 2005 to 2018, thi</span><span style="font-family:Verdana;">s paper analyzes the distribution and evolution of city scale in China by screening city samples according to the threshold criteria and using empirical research methods such as the City Primacy Index, the Rank-Scale Rule, the Gini coefficient of city scale, Kernel Density Estimation and Markov transfer matrix. The results show that: the most populous city in China has obvious advantages. The population distribution is concentrated in high order cities and in accordance with the law of order</span><span style="font-family:Verdana;">-</span><span style="font-family:""><span style="font-family:Verdana;">scale;the economic scale of cities is in a concentrated state, the gap between the economic development levels of different types of cities is large, and the megacities are more attractive, which to a certain extent limit the development of the scale of the rest of the cities;th</span><span style="font-family:Verdana;">e number of China’s city population is increasing, however, the ga</span><span style="font-family:Verdana;">p between the</span></span><span style="font-family:""> </span><span style="font-family:Verdana;">population scale of other cities and the most populous city continues to be large, and the structure of city population scale is not reasonable enough;megacities and megalopolises keep their original scale levels unchanged to a large extent, and the scale transition between the two types of cities is rather difficult. Finally, based on the explanatory framework of the dynamics of city scale evolution, policy recommendations are proposed to promote a more balanced distribution of city scale.</span>
文摘Introduction: The Liebowitz Social Anxiety Scale (LSAS), used to assess the severity of social anxiety disorder (SAD), requires considerable effort and time to complete. The aims of this study were: 1) to investigate whether a visual analogue scale (VAS) could be linear with the LSAS and substitute for the LSAS, 2) to relate such a VAS instrument to patient demographics. Methods: Fifty SAD patients were assessed using the LSAS and VAS instruments completed by both patients and doctors at the same session. We then drew distributions and calculated the Spearman’s ρ and κ coefficient values (divided at the median for each scale) between patient and doctor assessments. Next, each pair among the scores for the LSAS, the patient VAS and the doctor VAS was compared using Wilcoxon rank sum tests according to patient life profile data. Results: Scatter plots of pairs of scores were obtained. Spearman’s ρ was 0.661 between the LSAS and the patient VAS, 0.461 between the LSAS and the doctor VAS, and 0.494 between VAS scores of patients and doctors. The κ coefficients were 0.501 between the LSAS and patient VAS, 0.251 between the LSAS and doctor VAS, and 0.425 between patient VAS and doctor VAS (for all six, p < 0.001). The Wilcoxon rank sum tests indicated a significant difference between the groups with/ without “employment” (LSAS, patient/doctor VAS), with/without “graduation from junior college/university” (doctor VAS) (p < 0.05) and with/without marital history (the age of first consultation) (p < 0.01). Conclusions: A patient VAS may substitute for the LSAS and offer the versatility necessary to capture patient states and life profiles.
