Conspecific negative density dependence(CNDD)is a potentially important mechanism in maintaining species diversity.While previous evidence showed habitat heterogeneity and species’dispersal modes affect the strength ...Conspecific negative density dependence(CNDD)is a potentially important mechanism in maintaining species diversity.While previous evidence showed habitat heterogeneity and species’dispersal modes affect the strength of CNDD at early life stages of trees(e.g.,seedlings),it remains unclear how they affect the strength of CNDD at later life stages.We examined the degree of spatial aggregation between saplings and trees for species dispersed by wind and gravity in four topographic habitats within a 25-ha temperate forest dynamic plot in the Qinling Mountains of central China.We used the replicated spatial point pattern(RSPP)analysis and bivariate paircorrelation function(PCF)to detect the spatial distribution of saplings around trees at two scales,15 and 50 m,respectively.Although the signal was not apparent across the whole study region(or 25-ha),it is distinct on isolated areas with specific characteristics,suggesting that these characteristics could be important factors in CNDD.Further,we found that the gravity-dispersed tree species experienced CNDD across habitats,while for wind-dispersed species CNDD was found in gully,terrace and low-ridge habitats.Our study suggests that neglecting the habitat heterogeneity and dispersal mode can distort the signal of CNDD and community assembly in temperate forests.展开更多
To understand the anisotropy dependence of the damage evolution and material removal during the machining process of MgF_(2) single crystals,nanoscratch tests of MgF_(2) single crystals with different crystal planes a...To understand the anisotropy dependence of the damage evolution and material removal during the machining process of MgF_(2) single crystals,nanoscratch tests of MgF_(2) single crystals with different crystal planes and directions were systematically performed,and surface morphologies of the scratched grooves under different conditions were analyzed.The experimental results indicated that anisotropy considerably affected the damage evolution in the machining process of MgF_(2) single crystals.A stress field model induced by the scratch was developed by considering the anisotropy,which indicated that during the loading process,median cracks induced by the tensile stress initiated and propagated at the front of the indenter.Lateral cracks induced by tensile stress initiated and propagated on the subsurface during the unloading process.In addition,surface radial cracks induced by the tensile stress were easily generated during the unloading process.The stress change led to the deflection of the propagation direction of lateral cracks.Therefore,the lateral cracks propagated to the workpiece surface,resulting in brittle removal in the form of chunk chips.The plastic deformation parameter indicated that the more the slip systems were activated,the more easily the plastic deformation occurred.The cleavage fracture parameter indicated that the cracks propagated along the activated cleavage planes,and the brittle chunk removal was owing to the subsurface cleavage cracks propagating to the crystal surface.Under the same processing parameters,the scratch of the(001)crystal plane along the[100]crystal-orientation was found to be the most conducive to achieving plastic machining of MgF_(2) single crystals.The theoretical results agreed well with the experimental results,which will not only enhance the understanding of the anisotropy dependence of the damage evolution and removal process during the machining of MgF_(2) crystals,but also provide a theoretical foundation for achieving the high-efficiency and low-damage processing of anisotropic single crystals.展开更多
During extended warranty(EW)period,maintenance events play a key role in controlling the product systems within normal operations.However,the modelling of failure process and maintenance optimization is complicated ow...During extended warranty(EW)period,maintenance events play a key role in controlling the product systems within normal operations.However,the modelling of failure process and maintenance optimization is complicated owing to the complex features of the product system,namely,components of the multi-component system are interdependent with each other in some form.For the purpose of optimizing the EW pricing decision of the multi-component system scientifically and rationally,taking the series multi-component system with economic dependence sold with EW policy as a research object,this paper optimizes the imperfect preventive maintenance(PM)strategy from the standpoint of EW cost.Taking into consideration adjusting the PM moments of the components in the system,a group maintenance model is developed,in which the system is repaired preventively in accordance with a specified PM base interval.In order to compare with the system EW cost before group maintenance,the system EW cost model before group maintenance is developed.Numerical example demonstrates that offering group maintenance programs can reduce EW cost of the system to a great extent,thereby reducing the EW price,which proves to be a win-win strategy to manufacturers and users.展开更多
The majority of spatial data reveal some degree of spatial dependence. The term “spatial dependence” refers to the tendency for phenomena to be more similar when they occur close together than when they occur far ap...The majority of spatial data reveal some degree of spatial dependence. The term “spatial dependence” refers to the tendency for phenomena to be more similar when they occur close together than when they occur far apart in space. This property is ignored in machine learning (ML) for spatial domains of application. Most classical machine learning algorithms are generally inappropriate unless modified in some way to account for it. In this study, we proposed an approach that aimed to improve a ML model to detect the dependence without incorporating any spatial features in the learning process. To detect this dependence while also improving performance, a hybrid model was used based on two representative algorithms. In addition, cross-validation method was used to make the model stable. Furthermore, global moran’s I and local moran were used to capture the spatial dependence in the residuals. The results show that the HM has significant with a R2 of 99.91% performance compared to RBFNN and RF that have 74.22% and 82.26% as R2 respectively. With lower errors, the HM was able to achieve an average test error of 0.033% and a positive global moran’s of 0.12. We concluded that as the R2 value increases, the models become weaker in terms of capturing the dependence.展开更多
In this paper, we provide a method based on quantiles to estimate the parameters of a finite mixture of Fréchet distributions, for a large sample of strongly dependent data. This is a situation that appears when ...In this paper, we provide a method based on quantiles to estimate the parameters of a finite mixture of Fréchet distributions, for a large sample of strongly dependent data. This is a situation that appears when dealing with environmental data and there was a real need of such method. We validate our approach by means of estimation and goodness-of-fit testing over simulated data, showing an accurate performance.展开更多
In spinal cord injuries,external forces from various directions occur at various velocities.Therefore,it is important to physically evaluate whether the spinal cord is susceptible to damage and an increase in internal...In spinal cord injuries,external forces from various directions occur at various velocities.Therefore,it is important to physically evaluate whether the spinal cord is susceptible to damage and an increase in internal stress for external forces.We hypothesized that the spinal cord has mechanical features that vary under stress depending on the direction and velocity of injury.However,it is difficult to perform experiment because the spinal cord is very soft.There are no reports on the effects of multiple external forces.In this study,we used bovine spinal cord white matter to test and analyze the anisotropy and velocity dependence of the spinal cord.Tensile-vertical,tensile-parallel,shear-vertical,and shear-parallel tests were performed on the white matter in the fibrous direction(cranial to caudal).Strain rate in the experiment was 0.1,1,10,and 100/s.We calculated the Young’s modulus of the spinal cord.Results of the tensile and shear tests revealed that stress tended to increase when external forces were applied parallel to the direction of axon fibers,such as in tensile-vertical and shear-vertical tests.However,external forces those tear against the fibrous direction and vertically,such as in tensile-parallel and shear-parallel tests,were less likely to increase stress even with increased velocity.We found that the spinal cord was prone to external forces,especially in the direction of the fibers,and to be under increased stress levels when the velocity of external forces increased.From these results,we confirmed that the spinal cord has velocity dependence and anisotropy.The Institutional Animal Care and Use Committee of Yamaguchi University waived the requirement for ethical approval.展开更多
It has been predicted that high-order harmonic generation(HHG) in nanowires has the potential to scale up photon energy and harmonic yield.However,studies on HHG in nanowires are still theoretical and no relevant expe...It has been predicted that high-order harmonic generation(HHG) in nanowires has the potential to scale up photon energy and harmonic yield.However,studies on HHG in nanowires are still theoretical and no relevant experimental results have been reported as yet.Our experimental observation of the high-order harmonic in cadmium sulfide nanowires(CdS NWs) excited by a mid-infrared laser is,to our knowledge,the first of such study,and it verifies some of the theoretical results.Our experimental results show that the observed harmonics are strongest when a pump laser is parallel to the nanowires.Therefore,the theoretical prediction that harmonics are strongest under the nanowires parallel to the laser field is confirmed experimentally,and this can be used to determine the orientation of the nanowire.In addition,harmonics are sensitive to the variation of pump light ellipticities.This orientation dependence opens new opportunities to access the ultrafast and strong-field physics of nanowires.展开更多
We designed a Japanese version of the Smartphone Dependence Scale (J-SDS) for university students, and assessed its validity and reliability. For development of this scale, we initially selected 43 preliminary items b...We designed a Japanese version of the Smartphone Dependence Scale (J-SDS) for university students, and assessed its validity and reliability. For development of this scale, we initially selected 43 preliminary items based on previous studies of Internet and mobile phone dependence. Each response was scored using a Likert scale (0, 1, 2, 3), with higher scores indicating greater dependence. After administering the preliminary scale to 149 university students, the final 29 items were selected according to exploratory factor analysis. The final scale consisted of 5 factors: 1) craving and withdrawal, 2) overuse and tolerance, 3) virtual life orientation, 4) disturbance of concentration in class, and 5) physical symptoms. Reliability coefficient (Cronbach’s alpha) values for the 5 factors and total J-SDS were 0.87, 0.87, 0.76, 0.77, 0.69, and 0.92, respectively. We then summed the Likert scores for each item to provide a quantitative overall smartphone dependence score, with higher scores indicating greater dependence. The J-SDS score became significantly higher with longer hours of smartphone use (p < 0.001). Our results suggest that the J-SDS is a reliable and valid scale for screening university students who may be at risk of developing smartphone dependence.展开更多
We investigated associations between smartphone dependence and general health status or personality traits. To 197 medical university students, we administered a set of self-reporting questionnaires designed to evalua...We investigated associations between smartphone dependence and general health status or personality traits. To 197 medical university students, we administered a set of self-reporting questionnaires designed to evaluate these parameters. For males, smartphone dependence positively correlated with somatic symptoms, anxiety and insomnia, and emotional instability, and negatively correlated with agreeableness. For females, smartphone dependence positively correlated with somatic symptoms, severe depression, and extraversion, and negatively correlated with social dysfunction. These findings suggest that smartphone dependence may be associated with general health status or personality traits and that there may be a gender difference in these associations.展开更多
Field dependence/independence in Language Acquisition are discussed by many language learners.In this article,we will mainly focus on talking about the cognitive style,including the concept of Field-dependence/indepen...Field dependence/independence in Language Acquisition are discussed by many language learners.In this article,we will mainly focus on talking about the cognitive style,including the concept of Field-dependence/independence,their character istics and differences and functions in language acquisition.展开更多
The world today is in a period of great development and integration of economy,information,and technology,especially the high-tech industries represented by big data,cloud computing,and artificial intelligence.It is p...The world today is in a period of great development and integration of economy,information,and technology,especially the high-tech industries represented by big data,cloud computing,and artificial intelligence.It is promoting the rapid increase of human productivity and leading the changes in various industries.Enterprises are facing more and more uncertain external environments.The previous organizational strategy,personnel structure,and operating strategies have been unable to adapt to the turbulent external environment,and innovation has become the norm.Therefore,how to find an innovative breakthrough point on the original strategic road on which to survive has become a matter of life and death.From the perspective of path dependence theory,this paper analyzes the characteristics of path dependence and transcendence path dependence during the adjustment of corporate strategy,and analyzes the internal causes and mechanisms of its generation with the help of the PEST model.Based on this,the negative impact of path dependence on the adjustment of the strategy was found.Furthermore,it was found above that the degree of transcendence path dependence in corporate strategic adjustment is determined by two factors:its ability to drive independent innovation in a dynamic environment and its ability to transform strategically.Finally,according to the research conclusions,it proposes countermeasures to overcome the path dependence of enterprises when adjusting their strategies,and provides suggestions for companies to find breakthrough points in disruptive innovation.展开更多
The world today is in a period of great development and integration of economy,information,and technology,especially the high-tech industries represented by big data,cloud computing,and artificial intelligence.It is p...The world today is in a period of great development and integration of economy,information,and technology,especially the high-tech industries represented by big data,cloud computing,and artificial intelligence.It is promoting the rapid increase of human productivity and leading the changes in various industries.Enterprises are facing more and more uncertain external environments.The previous organizational strategy,personnel structure,and operating strategies have been unable to adapt to the turbulent external environment,and innovation has become the norm.Therefore,how to find an innovative breakthrough point on the original strategic road on which to survive has become a matter of life and death.From the perspective of path dependence theory,this paper analyzes the characteristics of path dependence and transcendence path dependence during the adjustment of corporate strategy,and analyzes the internal causes and mechanisms of its generation with the help of the PEST model.Based on this,the negative impact of path dependence on the adjustment of the strategy was found.Furthermore,it was found above that the degree of transcendence path dependence in corporate strategic adjustment is determined by two factors:its ability to drive independent innovation in a dynamic environment and its ability to transform strategically.Finally,according to the research conclusions,it proposes countermeasures to overcome the path dependence of enterprises when adjusting their strategies,and provides suggestions for companies to find breakthrough points in disruptive innovation.展开更多
The high rate of relapse among heroin users remains a significant public concern in China. In the present study, we utilized a Motivation-Skill-Desensitization-Mental Energy (MSDE) intervention and evaluated its effec...The high rate of relapse among heroin users remains a significant public concern in China. In the present study, we utilized a Motivation-Skill-Desensitization-Mental Energy (MSDE) intervention and evaluated its effects on abstinence and mental health. Eighty-nine male heroin users in a drug rehabilitation center were enrolled in the study. The participants in the MSDE intervention group (n=46) received MSDE intervention, which included motivational interviewing, coping skills training, eye movement desensitization and reprocessing, and mindfulness-based psychotherapy. The participants in the control group (h=43) received a series of lectures on skills training. A significant increase in Contemplation Ladder score (P<0.001) and decreases in scores on the Obsessive Compulsive Drug Use Scale (P<0.001), Beck Depression Inventory (P<0.001), and Aggression Questionnaire (P=O.O33) were found immediately after intervention. Compared to the control group, the MSDE intervention group reported significantly higher abstinence rates (P=0.027) and retention rates (P<0.001) at follow-up. Overall, the MSDE intervention, which uses a combined strategy for relapse prevention, could be a promising approach for preventing relapse among heroin users in China.展开更多
The concentration dependence of the reduced viscosity of dilute polymer solution is interpreted in the light of anew concept of the self-association of polymer chains in dilute solution. The apparent self-association ...The concentration dependence of the reduced viscosity of dilute polymer solution is interpreted in the light of anew concept of the self-association of polymer chains in dilute solution. The apparent self-association constant is defined asthe molar association constant divided by the molar mass of individual polymer chain and is numerically interconvertiblewith the Huggins coefficient. The molar association constant is directly proportional to the effective hydrodynamic volume ofthe polymer chain in solution and is irrespective of the chain architecture. The effective hydrodynamic volume accounts forthe non-spherical conformation of a short polymer chain in solution and is a product of a shape factor and hydrodynamicvolume. The observed enhancement of Huggins coefficient for short chain and branched polymer is satisfactorily interpretedby the concept of self-association. The concept of self-association allows us to predict the existence of a boundaryconcentration C_s (dynamic contact concentration) which divides the dilute polymer solution into two regions.展开更多
This paper presents a copula technique to develop time-variant seismic fragility curves for corroded bridges at the system level and considers the realistic time-varying dependence among component seismic demands. Bas...This paper presents a copula technique to develop time-variant seismic fragility curves for corroded bridges at the system level and considers the realistic time-varying dependence among component seismic demands. Based on material deterioration mechanisms and incremental dynamic analysis, the time-evolving seismic demands of components were obtained in the form of marginal probability distributions. The time-varying dependences among bridge components were then captured with the best fitting copula function, which was selected from the commonly used copula classes by the empirical distribution based analysis method. The system time-variant fragility curves at different damage states were developed and the effects of time-varying dependences among components on the bridge system fragility were investigated. The results indicate the time-varying dependence among components significantly affects the time-variant fragility of the bridge system. The copula technique captures the nonlinear dependence among component seismic demands accurately and easily by separating the marginal distributions and the dependence among them.展开更多
We investigated factors contributing to mobile phone dependence. To 139 medical students, we administered a self-reporting questionnaire designed to evaluate mobile phone dependence, health-related lifestyle, patterns...We investigated factors contributing to mobile phone dependence. To 139 medical students, we administered a self-reporting questionnaire designed to evaluate mobile phone dependence, health-related lifestyle, patterns of behavior, and depressive state. Multivariate logistic regression analysis revealed that scores for poor health-related lifestyle, Type A behavior pattern, and presence of depression are independently associated with degree of mobile phone dependency. These findings suggest that persons with an unhealthy lifestyle, Type A behavior traits, or depression might benefit from mobile phone use guidance.展开更多
We investigated factors contributing to Internet addiction in 105 Japanese medical students. The subjects were administered by a self-reporting questionnaire designed to evaluate demographic factors, Internet addictio...We investigated factors contributing to Internet addiction in 105 Japanese medical students. The subjects were administered by a self-reporting questionnaire designed to evaluate demographic factors, Internet addiction, loneliness, health-related lifestyle factors, depressive state, patterns of behavior, and mobile phone dependence. Results of multivariate logistic regression analysis indicated that loneliness and mobile phone dependence were positively related to degree of addiction. Our findings suggest that Internet addiction is associated with loneliness and mobile phone dependence in Japanese students.展开更多
In view of the high complexity of the objective world, an economic dependence between subsystems(paired and unpaired) is proposed, and then the maintenance cost and time under different economic dependences are formul...In view of the high complexity of the objective world, an economic dependence between subsystems(paired and unpaired) is proposed, and then the maintenance cost and time under different economic dependences are formulated in a simple and consistent manner. Selective maintenance problem under economic dependence(EDSMP) is presented based on a series–parallel system in this paper. A case study shows that the system reliability is promoted to a certain extent, which can validate the validity of the EDSMP model. The influence of the ratio of set-up cost on system performance is mainly discussed under different economic dependences. Several existing improvements of classical exhaust algorithm are further modified to solve a large sized EDSMP rapidly. Experimental results illustrate that these improvements can reduce CPU time significantly.Furthermore the contribution of each improvement is defined here, and then their contributions are compared thoroughly.展开更多
A series of coesite,coexisting with or without a liquid phase,was synthesized in the nominal system SiO2-H2O at800-1450℃and 5 GPa.Micro-Raman spectroscopy was used to identity the crystalline phase,electron microprob...A series of coesite,coexisting with or without a liquid phase,was synthesized in the nominal system SiO2-H2O at800-1450℃and 5 GPa.Micro-Raman spectroscopy was used to identity the crystalline phase,electron microprobe and LA-ICP-MS were employed to quantity some major and trace elements,and unpolarized FTIR spectroscopy was applied to probe the different types of hydrogen defects,explore water-incorporation mechanisms and quantify water contents.Trace amounts of A1 and B were detected in the coesite.Combining our results with the results in the literatures,we have found no positive correlation between the Al contents and the"Al"-based hydrogen concentrations,suggesting that previously proposed hydrogen-incorporation mechanism H^++Al^3+■Si^4+does not function in coesite.In contrast,we have confirmed the positive correlation between the B contents and the B-based hydrogen concentrations.The hydrogen-incorporation mechanism H^++B3^+■Si^4+readily takes place in coesite at different P-T conditions,and significantly increases the water content at both liquid-saturated and liquid-undersaturated conditions.For the SiO2-H2O system,we have found that type-Ⅰhydrogarnet substitution plays a dictating role in incorporating water into coesite at liquid-saturated condition,type-II hydrogarnet substitution contributes significantly at nearly dry condition,and both operate at conditions in between.The water solubility of coesite,as dictated by the type-Ⅰhydrogarnet substitution,positively correlates with both P and T,cH2O=-105(30)+5.2(32)×P+0.112(26)×T,with cH2O in wt ppm,P in GPa and T in℃.Due to its low water solubility and small fraction in subducted slabs,coesite may contribute insignificantly to the vertical water transport in subduction zones.Furthermore,the water solubility of any coesite in exhuming ultra-high pressure metamorphic rocks should be virtually zero as coesite becomes metastable.With an adequately fast waterdiffusion rate,this metastable coesite should be completely dry,which may have been the key factor to the partial preservation of most natural Coe.As a byproduct,a new IR experimental protocol for accurate water determination in optically anisotropic nominally anhydrous minerals has been found.Aided with the empirical method of Paterson(1982)it employs multiple unpolarized IR spectra,collected from randomly-orientated mineral grains,to approximate both total integrated absorbance and total integrated molar absorption coefficient.Its success relies on a high-level orientation randomness in the IR analyses.展开更多
基金Shihong Jia was financially supported by the National Natural Science Foundation of China(Grant No.32001120)the Fundamental Research Funds for the Central Universities(Grant No.31020200QD026)+1 种基金Qiulong Yin was supported by the National Natural Science Foundation of China(Grant No.32001171)Ying Luo was supported by the Innovation Capability Support Program of Shaanxi(Grant No.2022KRM090).
文摘Conspecific negative density dependence(CNDD)is a potentially important mechanism in maintaining species diversity.While previous evidence showed habitat heterogeneity and species’dispersal modes affect the strength of CNDD at early life stages of trees(e.g.,seedlings),it remains unclear how they affect the strength of CNDD at later life stages.We examined the degree of spatial aggregation between saplings and trees for species dispersed by wind and gravity in four topographic habitats within a 25-ha temperate forest dynamic plot in the Qinling Mountains of central China.We used the replicated spatial point pattern(RSPP)analysis and bivariate paircorrelation function(PCF)to detect the spatial distribution of saplings around trees at two scales,15 and 50 m,respectively.Although the signal was not apparent across the whole study region(or 25-ha),it is distinct on isolated areas with specific characteristics,suggesting that these characteristics could be important factors in CNDD.Further,we found that the gravity-dispersed tree species experienced CNDD across habitats,while for wind-dispersed species CNDD was found in gully,terrace and low-ridge habitats.Our study suggests that neglecting the habitat heterogeneity and dispersal mode can distort the signal of CNDD and community assembly in temperate forests.
基金supported by the National Natural Science Foundation of China (52005134&51975154)China Postdoctoral Science Foundation (2022T150163, 2020M670901)+4 种基金Self-Planned Task (No. SKLRS202214B) of State Key Laboratory of Robotics and System (HIT)Heilongjiang Postdoctoral Fund (LBH-Z20016)Shenzhen Science and Technology Program (GJHZ20210705142804012)Fundamental Research Funds for the Central Universities(FRFCU5710051122)Open Fund of ZJUT Xinchang Research Institute
文摘To understand the anisotropy dependence of the damage evolution and material removal during the machining process of MgF_(2) single crystals,nanoscratch tests of MgF_(2) single crystals with different crystal planes and directions were systematically performed,and surface morphologies of the scratched grooves under different conditions were analyzed.The experimental results indicated that anisotropy considerably affected the damage evolution in the machining process of MgF_(2) single crystals.A stress field model induced by the scratch was developed by considering the anisotropy,which indicated that during the loading process,median cracks induced by the tensile stress initiated and propagated at the front of the indenter.Lateral cracks induced by tensile stress initiated and propagated on the subsurface during the unloading process.In addition,surface radial cracks induced by the tensile stress were easily generated during the unloading process.The stress change led to the deflection of the propagation direction of lateral cracks.Therefore,the lateral cracks propagated to the workpiece surface,resulting in brittle removal in the form of chunk chips.The plastic deformation parameter indicated that the more the slip systems were activated,the more easily the plastic deformation occurred.The cleavage fracture parameter indicated that the cracks propagated along the activated cleavage planes,and the brittle chunk removal was owing to the subsurface cleavage cracks propagating to the crystal surface.Under the same processing parameters,the scratch of the(001)crystal plane along the[100]crystal-orientation was found to be the most conducive to achieving plastic machining of MgF_(2) single crystals.The theoretical results agreed well with the experimental results,which will not only enhance the understanding of the anisotropy dependence of the damage evolution and removal process during the machining of MgF_(2) crystals,but also provide a theoretical foundation for achieving the high-efficiency and low-damage processing of anisotropic single crystals.
基金supported by the National Natural Science Foundation of China(71871219).
文摘During extended warranty(EW)period,maintenance events play a key role in controlling the product systems within normal operations.However,the modelling of failure process and maintenance optimization is complicated owing to the complex features of the product system,namely,components of the multi-component system are interdependent with each other in some form.For the purpose of optimizing the EW pricing decision of the multi-component system scientifically and rationally,taking the series multi-component system with economic dependence sold with EW policy as a research object,this paper optimizes the imperfect preventive maintenance(PM)strategy from the standpoint of EW cost.Taking into consideration adjusting the PM moments of the components in the system,a group maintenance model is developed,in which the system is repaired preventively in accordance with a specified PM base interval.In order to compare with the system EW cost before group maintenance,the system EW cost model before group maintenance is developed.Numerical example demonstrates that offering group maintenance programs can reduce EW cost of the system to a great extent,thereby reducing the EW price,which proves to be a win-win strategy to manufacturers and users.
文摘The majority of spatial data reveal some degree of spatial dependence. The term “spatial dependence” refers to the tendency for phenomena to be more similar when they occur close together than when they occur far apart in space. This property is ignored in machine learning (ML) for spatial domains of application. Most classical machine learning algorithms are generally inappropriate unless modified in some way to account for it. In this study, we proposed an approach that aimed to improve a ML model to detect the dependence without incorporating any spatial features in the learning process. To detect this dependence while also improving performance, a hybrid model was used based on two representative algorithms. In addition, cross-validation method was used to make the model stable. Furthermore, global moran’s I and local moran were used to capture the spatial dependence in the residuals. The results show that the HM has significant with a R2 of 99.91% performance compared to RBFNN and RF that have 74.22% and 82.26% as R2 respectively. With lower errors, the HM was able to achieve an average test error of 0.033% and a positive global moran’s of 0.12. We concluded that as the R2 value increases, the models become weaker in terms of capturing the dependence.
文摘In this paper, we provide a method based on quantiles to estimate the parameters of a finite mixture of Fréchet distributions, for a large sample of strongly dependent data. This is a situation that appears when dealing with environmental data and there was a real need of such method. We validate our approach by means of estimation and goodness-of-fit testing over simulated data, showing an accurate performance.
基金This work was supported by the Japan Society for the Promotion of Science(KARENHI grant number JP 15K20002)by the Yamaguchi University Hospital(a translational promotion grant).
文摘In spinal cord injuries,external forces from various directions occur at various velocities.Therefore,it is important to physically evaluate whether the spinal cord is susceptible to damage and an increase in internal stress for external forces.We hypothesized that the spinal cord has mechanical features that vary under stress depending on the direction and velocity of injury.However,it is difficult to perform experiment because the spinal cord is very soft.There are no reports on the effects of multiple external forces.In this study,we used bovine spinal cord white matter to test and analyze the anisotropy and velocity dependence of the spinal cord.Tensile-vertical,tensile-parallel,shear-vertical,and shear-parallel tests were performed on the white matter in the fibrous direction(cranial to caudal).Strain rate in the experiment was 0.1,1,10,and 100/s.We calculated the Young’s modulus of the spinal cord.Results of the tensile and shear tests revealed that stress tended to increase when external forces were applied parallel to the direction of axon fibers,such as in tensile-vertical and shear-vertical tests.However,external forces those tear against the fibrous direction and vertically,such as in tensile-parallel and shear-parallel tests,were less likely to increase stress even with increased velocity.We found that the spinal cord was prone to external forces,especially in the direction of the fibers,and to be under increased stress levels when the velocity of external forces increased.From these results,we confirmed that the spinal cord has velocity dependence and anisotropy.The Institutional Animal Care and Use Committee of Yamaguchi University waived the requirement for ethical approval.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.91950203,11874374,61690223,and 11774363)the Youth Innovation Promotion Association of the Chinese Academy Sciencesthe Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB16)。
文摘It has been predicted that high-order harmonic generation(HHG) in nanowires has the potential to scale up photon energy and harmonic yield.However,studies on HHG in nanowires are still theoretical and no relevant experimental results have been reported as yet.Our experimental observation of the high-order harmonic in cadmium sulfide nanowires(CdS NWs) excited by a mid-infrared laser is,to our knowledge,the first of such study,and it verifies some of the theoretical results.Our experimental results show that the observed harmonics are strongest when a pump laser is parallel to the nanowires.Therefore,the theoretical prediction that harmonics are strongest under the nanowires parallel to the laser field is confirmed experimentally,and this can be used to determine the orientation of the nanowire.In addition,harmonics are sensitive to the variation of pump light ellipticities.This orientation dependence opens new opportunities to access the ultrafast and strong-field physics of nanowires.
文摘We designed a Japanese version of the Smartphone Dependence Scale (J-SDS) for university students, and assessed its validity and reliability. For development of this scale, we initially selected 43 preliminary items based on previous studies of Internet and mobile phone dependence. Each response was scored using a Likert scale (0, 1, 2, 3), with higher scores indicating greater dependence. After administering the preliminary scale to 149 university students, the final 29 items were selected according to exploratory factor analysis. The final scale consisted of 5 factors: 1) craving and withdrawal, 2) overuse and tolerance, 3) virtual life orientation, 4) disturbance of concentration in class, and 5) physical symptoms. Reliability coefficient (Cronbach’s alpha) values for the 5 factors and total J-SDS were 0.87, 0.87, 0.76, 0.77, 0.69, and 0.92, respectively. We then summed the Likert scores for each item to provide a quantitative overall smartphone dependence score, with higher scores indicating greater dependence. The J-SDS score became significantly higher with longer hours of smartphone use (p < 0.001). Our results suggest that the J-SDS is a reliable and valid scale for screening university students who may be at risk of developing smartphone dependence.
文摘We investigated associations between smartphone dependence and general health status or personality traits. To 197 medical university students, we administered a set of self-reporting questionnaires designed to evaluate these parameters. For males, smartphone dependence positively correlated with somatic symptoms, anxiety and insomnia, and emotional instability, and negatively correlated with agreeableness. For females, smartphone dependence positively correlated with somatic symptoms, severe depression, and extraversion, and negatively correlated with social dysfunction. These findings suggest that smartphone dependence may be associated with general health status or personality traits and that there may be a gender difference in these associations.
文摘Field dependence/independence in Language Acquisition are discussed by many language learners.In this article,we will mainly focus on talking about the cognitive style,including the concept of Field-dependence/independence,their character istics and differences and functions in language acquisition.
文摘The world today is in a period of great development and integration of economy,information,and technology,especially the high-tech industries represented by big data,cloud computing,and artificial intelligence.It is promoting the rapid increase of human productivity and leading the changes in various industries.Enterprises are facing more and more uncertain external environments.The previous organizational strategy,personnel structure,and operating strategies have been unable to adapt to the turbulent external environment,and innovation has become the norm.Therefore,how to find an innovative breakthrough point on the original strategic road on which to survive has become a matter of life and death.From the perspective of path dependence theory,this paper analyzes the characteristics of path dependence and transcendence path dependence during the adjustment of corporate strategy,and analyzes the internal causes and mechanisms of its generation with the help of the PEST model.Based on this,the negative impact of path dependence on the adjustment of the strategy was found.Furthermore,it was found above that the degree of transcendence path dependence in corporate strategic adjustment is determined by two factors:its ability to drive independent innovation in a dynamic environment and its ability to transform strategically.Finally,according to the research conclusions,it proposes countermeasures to overcome the path dependence of enterprises when adjusting their strategies,and provides suggestions for companies to find breakthrough points in disruptive innovation.
文摘The world today is in a period of great development and integration of economy,information,and technology,especially the high-tech industries represented by big data,cloud computing,and artificial intelligence.It is promoting the rapid increase of human productivity and leading the changes in various industries.Enterprises are facing more and more uncertain external environments.The previous organizational strategy,personnel structure,and operating strategies have been unable to adapt to the turbulent external environment,and innovation has become the norm.Therefore,how to find an innovative breakthrough point on the original strategic road on which to survive has become a matter of life and death.From the perspective of path dependence theory,this paper analyzes the characteristics of path dependence and transcendence path dependence during the adjustment of corporate strategy,and analyzes the internal causes and mechanisms of its generation with the help of the PEST model.Based on this,the negative impact of path dependence on the adjustment of the strategy was found.Furthermore,it was found above that the degree of transcendence path dependence in corporate strategic adjustment is determined by two factors:its ability to drive independent innovation in a dynamic environment and its ability to transform strategically.Finally,according to the research conclusions,it proposes countermeasures to overcome the path dependence of enterprises when adjusting their strategies,and provides suggestions for companies to find breakthrough points in disruptive innovation.
基金This study was funded by the National Natural Science Foundation of China (No.30872175,No.81573236).
文摘The high rate of relapse among heroin users remains a significant public concern in China. In the present study, we utilized a Motivation-Skill-Desensitization-Mental Energy (MSDE) intervention and evaluated its effects on abstinence and mental health. Eighty-nine male heroin users in a drug rehabilitation center were enrolled in the study. The participants in the MSDE intervention group (n=46) received MSDE intervention, which included motivational interviewing, coping skills training, eye movement desensitization and reprocessing, and mindfulness-based psychotherapy. The participants in the control group (h=43) received a series of lectures on skills training. A significant increase in Contemplation Ladder score (P<0.001) and decreases in scores on the Obsessive Compulsive Drug Use Scale (P<0.001), Beck Depression Inventory (P<0.001), and Aggression Questionnaire (P=O.O33) were found immediately after intervention. Compared to the control group, the MSDE intervention group reported significantly higher abstinence rates (P=0.027) and retention rates (P<0.001) at follow-up. Overall, the MSDE intervention, which uses a combined strategy for relapse prevention, could be a promising approach for preventing relapse among heroin users in China.
基金This work was supported by the Chinese National Basic Research Project "Macromolecular Condensed State" and National Natural Science Foundation of China
文摘The concentration dependence of the reduced viscosity of dilute polymer solution is interpreted in the light of anew concept of the self-association of polymer chains in dilute solution. The apparent self-association constant is defined asthe molar association constant divided by the molar mass of individual polymer chain and is numerically interconvertiblewith the Huggins coefficient. The molar association constant is directly proportional to the effective hydrodynamic volume ofthe polymer chain in solution and is irrespective of the chain architecture. The effective hydrodynamic volume accounts forthe non-spherical conformation of a short polymer chain in solution and is a product of a shape factor and hydrodynamicvolume. The observed enhancement of Huggins coefficient for short chain and branched polymer is satisfactorily interpretedby the concept of self-association. The concept of self-association allows us to predict the existence of a boundaryconcentration C_s (dynamic contact concentration) which divides the dilute polymer solution into two regions.
基金Natural Science Foundation of China under Grant No.51808376
文摘This paper presents a copula technique to develop time-variant seismic fragility curves for corroded bridges at the system level and considers the realistic time-varying dependence among component seismic demands. Based on material deterioration mechanisms and incremental dynamic analysis, the time-evolving seismic demands of components were obtained in the form of marginal probability distributions. The time-varying dependences among bridge components were then captured with the best fitting copula function, which was selected from the commonly used copula classes by the empirical distribution based analysis method. The system time-variant fragility curves at different damage states were developed and the effects of time-varying dependences among components on the bridge system fragility were investigated. The results indicate the time-varying dependence among components significantly affects the time-variant fragility of the bridge system. The copula technique captures the nonlinear dependence among component seismic demands accurately and easily by separating the marginal distributions and the dependence among them.
文摘We investigated factors contributing to mobile phone dependence. To 139 medical students, we administered a self-reporting questionnaire designed to evaluate mobile phone dependence, health-related lifestyle, patterns of behavior, and depressive state. Multivariate logistic regression analysis revealed that scores for poor health-related lifestyle, Type A behavior pattern, and presence of depression are independently associated with degree of mobile phone dependency. These findings suggest that persons with an unhealthy lifestyle, Type A behavior traits, or depression might benefit from mobile phone use guidance.
文摘We investigated factors contributing to Internet addiction in 105 Japanese medical students. The subjects were administered by a self-reporting questionnaire designed to evaluate demographic factors, Internet addiction, loneliness, health-related lifestyle factors, depressive state, patterns of behavior, and mobile phone dependence. Results of multivariate logistic regression analysis indicated that loneliness and mobile phone dependence were positively related to degree of addiction. Our findings suggest that Internet addiction is associated with loneliness and mobile phone dependence in Japanese students.
基金supported by the National Science Foundation of China (Grant No. 61305083)
文摘In view of the high complexity of the objective world, an economic dependence between subsystems(paired and unpaired) is proposed, and then the maintenance cost and time under different economic dependences are formulated in a simple and consistent manner. Selective maintenance problem under economic dependence(EDSMP) is presented based on a series–parallel system in this paper. A case study shows that the system reliability is promoted to a certain extent, which can validate the validity of the EDSMP model. The influence of the ratio of set-up cost on system performance is mainly discussed under different economic dependences. Several existing improvements of classical exhaust algorithm are further modified to solve a large sized EDSMP rapidly. Experimental results illustrate that these improvements can reduce CPU time significantly.Furthermore the contribution of each improvement is defined here, and then their contributions are compared thoroughly.
基金financially supported by the DREAM project of MOST,China(Grant No.2016YFC0600408)the Strategic Priority Research Program(B)of Chinese Academy of Sciences(Grant No.XDB18000000)the Program of the National Mineral Rock and Fossil Specimens Resource Center from MOST,China。
文摘A series of coesite,coexisting with or without a liquid phase,was synthesized in the nominal system SiO2-H2O at800-1450℃and 5 GPa.Micro-Raman spectroscopy was used to identity the crystalline phase,electron microprobe and LA-ICP-MS were employed to quantity some major and trace elements,and unpolarized FTIR spectroscopy was applied to probe the different types of hydrogen defects,explore water-incorporation mechanisms and quantify water contents.Trace amounts of A1 and B were detected in the coesite.Combining our results with the results in the literatures,we have found no positive correlation between the Al contents and the"Al"-based hydrogen concentrations,suggesting that previously proposed hydrogen-incorporation mechanism H^++Al^3+■Si^4+does not function in coesite.In contrast,we have confirmed the positive correlation between the B contents and the B-based hydrogen concentrations.The hydrogen-incorporation mechanism H^++B3^+■Si^4+readily takes place in coesite at different P-T conditions,and significantly increases the water content at both liquid-saturated and liquid-undersaturated conditions.For the SiO2-H2O system,we have found that type-Ⅰhydrogarnet substitution plays a dictating role in incorporating water into coesite at liquid-saturated condition,type-II hydrogarnet substitution contributes significantly at nearly dry condition,and both operate at conditions in between.The water solubility of coesite,as dictated by the type-Ⅰhydrogarnet substitution,positively correlates with both P and T,cH2O=-105(30)+5.2(32)×P+0.112(26)×T,with cH2O in wt ppm,P in GPa and T in℃.Due to its low water solubility and small fraction in subducted slabs,coesite may contribute insignificantly to the vertical water transport in subduction zones.Furthermore,the water solubility of any coesite in exhuming ultra-high pressure metamorphic rocks should be virtually zero as coesite becomes metastable.With an adequately fast waterdiffusion rate,this metastable coesite should be completely dry,which may have been the key factor to the partial preservation of most natural Coe.As a byproduct,a new IR experimental protocol for accurate water determination in optically anisotropic nominally anhydrous minerals has been found.Aided with the empirical method of Paterson(1982)it employs multiple unpolarized IR spectra,collected from randomly-orientated mineral grains,to approximate both total integrated absorbance and total integrated molar absorption coefficient.Its success relies on a high-level orientation randomness in the IR analyses.
