Based on studies of petrography, mineralogy and mineral chemistry, deep mantle fluids and their products in kimberlites and diamonds can be assorted into the ultradeep fluid-transmitted minerals with an oxygen-free fe...Based on studies of petrography, mineralogy and mineral chemistry, deep mantle fluids and their products in kimberlites and diamonds can be assorted into the ultradeep fluid-transmitted minerals with an oxygen-free feature, the deep fluid metasomatized-minerals characterized by enrichment in TiO2, K2O, BaO, REE and Fe3+, and the deep fluid-reformed minerals. The three types show a successive descent in fluid origin depth and metasomatism strength, and they have brought forth a series of corresponding metasomatic products.展开更多
This paper provides an efficient and useful approach for demand estimation and assortment planning of cell phone cards in wireless communication industry. We use maximum likelihood estimation to estimate the primary d...This paper provides an efficient and useful approach for demand estimation and assortment planning of cell phone cards in wireless communication industry. We use maximum likelihood estimation to estimate the primary demand and substitution probability of each cell phone card based on historical sales data. This estimation model is nonlinear, so we transform it to a mixed integer linear programming model by logarithmic transformations and piecewise'linear approximation. On the basis of the estimation results, we can make assortment planning. Considering the resource of cell phone cards is limited, we jointly optimize the assortment and quantity planning of cell phone cards. In numerical study, we apply our approach to a large mobile service provider in China and frod our approach can increase the revenue of this mobile service provider by 23.69%. Sensitivity analysis shows the mobile service provider should provide more assortments to increase revenue when the types of cell phone cards that can be assigned to each store are limited.展开更多
With increasing varieties and products,management of limited shelf space becomes quite difficult for retailers.Hence,an efficient product assortment,which in turn helps to plan the organization of various products acr...With increasing varieties and products,management of limited shelf space becomes quite difficult for retailers.Hence,an efficient product assortment,which in turn helps to plan the organization of various products across limited shelf space,is extremely important for retailers.Products can be distinguished based on quality,price,brand,and other attributes,and decision needs to be made about an assortment of the products based on these attributes.An efficient assortment planning improves the financial performance of the retailer by increasing profits and reducing operational costs.Clustering techniques can be very effective in grouping products,stores,etc.and help managers solve the problem of assortment planning.This paper proposes data mining approaches for assortment planning for profit maximization with space,and cost constraints by mapping it into well-known knapsack problem.展开更多
In this work,we study the conic quadratic mixed-integer formulation for assortment optimization problem under the mixture of multinomial logit(MMNL)model.The MMNL model generalizes the widely studied multinomial logit...In this work,we study the conic quadratic mixed-integer formulation for assortment optimization problem under the mixture of multinomial logit(MMNL)model.The MMNL model generalizes the widely studied multinomial logit choice model and can approximate any random utility model with an arbitrary additive error.An important operational decision problem in revenue management is assortment optimization problem,which aims to find a subset of products to make available to customers that maximizes the expected revenue of the retailer.It is known that assortment optimization problem under the MMNL model is NP-hard and inapproximable within any constant performance guarantee.Commonly used methods for solving such problem are heuristical approaches or customized combinatorial optimization approaches.In the meanwhile,studies related to global optimization approaches are relatively scarce.We propose an enhanced conic quadratic mixed-integer formulation for solving assortment optimization problem under the MMNL model with a higher computational efficiency.Furthermore,we conduct extensive numerical experiments to demonstrate that the proposed reformulation significantly outperforms the existing conic reformulations for assortment optimization under the MMNL model.展开更多
If assortment priee parity of Clase coking coal and its qtalty price danrcnee is nonreasonable, it deren't gulde in Anprotrig tbe quallry metaliurgical coking coal and may be influence theeconomic benefit of me...If assortment priee parity of Clase coking coal and its qtalty price danrcnee is nonreasonable, it deren't gulde in Anprotrig tbe quallry metaliurgical coking coal and may be influence theeconomic benefit of metallurgical enterprises. This paper propose the principles and mathematicmodel for determination aseortment party of clean cokingcoal and its quality difference of ash content in clean coking coal in order to urge wasbenes into producing superior clean coking cleal whichis under condition of consideration both interest waskeries and interest metallurgicai industry. It canbe used as a method in theory to make price strategies under condition of socialism maket economicfor washeries of clean coking coal展开更多
Based on an investigation on the current situation of SPM in some enterprises, this paper presents the common probletns and poor fields existing in SPM in enterprise; analyzes the reasons which resulted in the situati...Based on an investigation on the current situation of SPM in some enterprises, this paper presents the common probletns and poor fields existing in SPM in enterprise; analyzes the reasons which resulted in the situation, and then puts forward some feasible measures to improve it. Lastly, some fields that should be paid more attention in SPM are provided.展开更多
An estimate of the upper bound is given for the double determinant of the sum of two arbitrary quaternion matrices, and meanwhile the lower bound on the double determinant is established especially for the sum of two ...An estimate of the upper bound is given for the double determinant of the sum of two arbitrary quaternion matrices, and meanwhile the lower bound on the double determinant is established especially for the sum of two quaternion matrices which form an assortive pair. As applications, some known results are obtained as corollaries and a question in the matrix determinant theory is answered completely.展开更多
In real-world networks,there usually exist a small set of nodes that play an important role in the structure and function of networks.Those vital nodes can influence most of other nodes in the network via a spreading ...In real-world networks,there usually exist a small set of nodes that play an important role in the structure and function of networks.Those vital nodes can influence most of other nodes in the network via a spreading process.While most of the existing works focused on vital nodes that can maximize the spreading size in the final stage,which we call final influencers,recent work proposed the idea of fast influencers,which emphasizes nodes’spreading capacity at the early stage.Despite the recent surge of efforts in identifying these two types of influencers in networks,there remained limited research on untangling the differences between the fast influencers and final influencers.In this paper,we firstly distinguish the two types of influencers:fast-only influencers and final-only influencers.The former is defined as individuals who can achieve a high spreading effect at the early stage but lose their superiority in the final stage,and the latter are those individuals that fail to exhibit a prominent spreading performance at the early stage but influence a large fraction of nodes at the final stage.Further experiments are based on eight empirical datasets,and we reveal the key differences between the two types of influencers concerning their spreading capacity and the local structures.We also analyze how network degree assortativity influences the fraction of the proposed two types of influencers.The results demonstrate that with the increase of degree assortativity,the fraction of the fast-only influencers decreases,which indicates that more fast influencers tend to keep their superiority at the final stage.Our study provides insights into the differences and evolution of different types of influencers and has important implications for various empirical applications,such as advertisement marketing and epidemic suppressing.展开更多
It is a challenging task to investigate the different in- fluence of long-range and short-range interactions on two-state and three-state folding kinetics of protein. The networks of the 30 two-state proteins and 15 t...It is a challenging task to investigate the different in- fluence of long-range and short-range interactions on two-state and three-state folding kinetics of protein. The networks of the 30 two-state proteins and 15 three-state proteins were constructed by complex networks analysis at three length scales: Protein Contact Networks, Long-range Interaction Networks and Short-range Interaction Networks. To uncover the relationship between structural properties and folding kinetics of the proteins, the correlations of protein network parameters with protein folding rate and topology parameters contact order were analyzed. The results show that Protein Contact Networks and Short-range Interaction Networks (for both two-state and three-state proteins) exhibit the “small-world” property and Long-range Interaction networks indicate “scale-free” behavior. Our results further indicate that all Protein Contact Networks and Short- range Interaction networks are assortative type. While some of Long-range Interaction Networks are of assortative type, the others are of disassortative type. For two-state proteins, the clustering coefficients of Short-range Interaction Networks show prominent correlation with folding rate and contact order. The assortativity coefficients of Short-range Interaction Networks also show remarkable correlation with folding rate and contact order. Similar correlations exist in Protein Contact Networks of three-state proteins. For two-state proteins, the correlation between contact order and folding rate is determined by the numbers of local contacts. Short- range interactions play a key role in determining the connecting trend among amino acids and they impact the folding rate of two-state proteins directly. For three-state proteins, the folding rate is determined by short-range and long-range interactions among residues together.展开更多
Sex differences in plumage color are common in bird species.Some bird species are regarded as sexually monochromatic in human visual systems,and in recent years,some species are found to be of cryptic(to human)sexual ...Sex differences in plumage color are common in bird species.Some bird species are regarded as sexually monochromatic in human visual systems,and in recent years,some species are found to be of cryptic(to human)sexual dichromatism by spectrophotometric techniques.However,the functions of plumage color are still less understood in these species.Here,we focused on plumage color traits in the Chestnut Thrush(Turdus rubrocanus),which is considered as a sexually monochromatic bird by human observers.We used spectrometer analyses and avian visual modeling to investigate the color traits of males and females,and whether these color traits are involved in assortative mating.We found that Chestnut Thrush showed sexual dichromatism in bill,throat and wing,and pairs mated assortatively with colorations of throat,chest,crown and wing.We also found that color of tarsus was different between two consecutive years.These results revealed that Chestnut Thrush is sexually dichromatic in the avian visual system,and plumage color traits play important roles in mate choice.展开更多
Wolbachia are a group of intracellular bacteria, ma-ternally transmitted from infected females to their offspring, which affect a wide range of arthropods. Their presence is associated with Cytoplasmic Incompatibility...Wolbachia are a group of intracellular bacteria, ma-ternally transmitted from infected females to their offspring, which affect a wide range of arthropods. Their presence is associated with Cytoplasmic Incompatibility (CI) in crosses between infected males and uninfected females and between populations carrying different strains of Wolbachia. The negative influence of Wolbachia a infection on progeny fitness in incompatible crosses can be considered a first step in the appearance of reproductive isolation between infected and uninfected individuals. In this work, we examined the possibility of assortative mating in response to Wolbachia infection, a response that evolved as an incipient mechanism of sexual isolation in the species D. melanogaster and D. simulans. We found that the females of each species could detect the presence of the bacterium in the other sex and chose to mate with males who had the same state of infection, whereas the males randomly attempted to mate with both infected and uninfected females. Thus, Wolbachia may act as an additive factor influencing sexual isolation in Drosophila populations and may play a role in speciation events.展开更多
Purpose: This paper tries to understand the dynamics of scientific communication systems during crises by investigating as a case study the blogging activities that took place during the period of the 2011 earthquake ...Purpose: This paper tries to understand the dynamics of scientific communication systems during crises by investigating as a case study the blogging activities that took place during the period of the 2011 earthquake and related events in Japan. Interactions between bloggers and registered users are studied quantitatively and qualitatively at Sciencenet.cn, an influential science-related blogosphere in China.Design/methodology/approach: The editors of Sciencenet.cn compiled a special issue of science blog articles under the title Analysis of the Japanese Earthquake. We developed a spider program and downloaded from this special issue the metadata about title, content,publishing time, total read count, reply count and recommendation count, and further collected information about bloggers and recommenders. We then sent a short message to the bloggers who wrote articles on these emergencies, asking for their educational and professional background.Findings: We found that knowledge reflected in the blog articles is strongly related to the educational and professional background of bloggers. Knowledge diffusion is facilitated by interactions, such as recommendations, comments and answers. Interactions via comments and recommendations are of an assortative nature: A blog article is more likelyto be commented on and recommended by those bloggers who write on the same or similar topics than by those writing on a different one. Registered users tend to give comments on articles dealing with the topic that they recommend, and vice versa.Interaction in the intersection of two or three topics is more intense than that within one topic. The impact of blog articles is also influenced by other factors, such as the reputation of the blogger and the type of information they contain.Implications and limitations: It is confirmed that studying blogs is a valid approach within informetric studies. Yet, we only studied one triple(earthquake, tsunami, nuclear disaster) event based on data originating from one Chinese blog website. More events should be studied.Originality/value: Informetric studies based on blogs are still relatively few. Using science blogs and combining comments on a triple event with the knowledge background of bloggers in China is even less common. As such this contribution enhances our knowledge on this new form of science communication activity.展开更多
A major component rice variety of Xiangwanxian 9 (a late Indica variety) with 13.1%, 15.6% and 18. 3% of the moisture was respectively mixed with three ad-ditive varieties in 13% of moisture at ration of 7:3 for proce...A major component rice variety of Xiangwanxian 9 (a late Indica variety) with 13.1%, 15.6% and 18. 3% of the moisture was respectively mixed with three ad-ditive varieties in 13% of moisture at ration of 7:3 for processing assorted rices. Head rice recovery of the treatments was determined 24 hours later. Analysis indicated sig-nificant differences exist in the effects produced by the component varieties, their moistures and the component variety moisture.展开更多
This paper proposes a novel complex network with assortative property based on multi-center networks. The average path length and clustering coefficient of the network are calculated, and the impact on the network top...This paper proposes a novel complex network with assortative property based on multi-center networks. The average path length and clustering coefficient of the network are calculated, and the impact on the network topology is investigated. A simple dynamic system established on the proposed network is used to analyze how the assortative property of the network affects synchronization.展开更多
For most networks, the weight of connection is changing with their attachment and inner affinity. By introducing a mixed mechanism of weighted-driven and inner selection, the model exhibits wide range power-law distri...For most networks, the weight of connection is changing with their attachment and inner affinity. By introducing a mixed mechanism of weighted-driven and inner selection, the model exhibits wide range power-law distributions of node strength and edge weight, and the exponent can be adjusted by not only the parameter δ but also the probability q. Furthermore, we investigate the weighted average shortest distance, clustering coefficient, and the correlation of our network. In addition, the weighted assortativity coefficient which characterizes important information of weighted topological networks has been discussed, but the variation of coefficients is much smaller than the former researches.展开更多
Reproductive isolation is the basis of the Biological Species Definition and can be a driving force of speciation. Theoretical studies have provided models of how reproductive isolation can arise within individual spe...Reproductive isolation is the basis of the Biological Species Definition and can be a driving force of speciation. Theoretical studies have provided models of how reproductive isolation can arise within individual species. Genetic tests of these models are limited to populations in which reproductive isolation is present but not complete. Here, reproductive isolation in the Elgans-Group of the nematode genus Caenorhabditis is reviewed. Pre-mating barriers, assortative fertilization and post-zygotic barriers all have been observed in this clade. In some combinations of species, fertile F1 hybrids can be obtained. Therefore, the Elegans-Group of Caenorhabditis is poised to become an important experimental system for the study of reproductive isolation.展开更多
This study aims to contribute to marketing theory by applying monopolistic competition theory to investigate how differentiation affects online retailers7 pricing power. We examine the intermediary effect of customer ...This study aims to contribute to marketing theory by applying monopolistic competition theory to investigate how differentiation affects online retailers7 pricing power. We examine the intermediary effect of customer loyalty on the relationship between differentiation and pricing power of online retailers. We assume that customers have different preferences for the differentiated characteristics of online retailers, and thus different degrees of willingness to pay premiums, which gives online retailers pricing power. Structural equation modeling (SEM) is employed to test the hypothesized relati on ships between differentiation, customer loyalty, and pricing power. The statistical results of the empirical data indicate that some of the differentiation characteristics of online retailers can cultivate their pricing power indirectly. Logistics quality followed by commodity assortment and transaction security produces profound effects on the buildup of pricing power with customer loyalty as an intermediary factor. Results further reveal that commodity quality is positively related to pricing power. This study expands the definition of differentiation by combining corporate strategic positioning with commodity pricing. Implications for practice and di recti ons for future research are provided.展开更多
The extent to which sexual selection is involved in speciation with gene flow remains an open question and the sub- ject of much research. Here, we propose that some insight can be gained from considering the concept ...The extent to which sexual selection is involved in speciation with gene flow remains an open question and the sub- ject of much research. Here, we propose that some insight can be gained from considering the concept of magic traits (i.e., traits involved in both reproductive isolation and ecological divergence). Both magic traits and other, "non-magic", traits can contribute to speciation via a number of specific mechanisms. We argue that many of these mechanisms are likely to differ widely in the ex- tent to which they involve sexual selection. Furthermore, in some cases where sexual selection is present, it may be prone to in- hibit rather than drive speciation. Finally, there are a priori reasons to believe that certain categories of traits are much more ef- fective than others in driving speciation. The combination of these points suggests a classification of traits that may shed light on the broader role of sexual selection in speciation with gene flow. In particular, we suggest that sexual selection can act as a driver of speciation in some scenarios, but may play a negligible role in potentially common categories of magic traits, and may be likely to inhibit speciation in common categories of non-magic traits [Current Zoology 58 (3): 510-516, 2012].展开更多
Genetic, life history, and environmental factors dictate patterns of variation in sexual traits within and across popula- tions, and thus the action and outcome of sexual selection. This study explores patterns of inh...Genetic, life history, and environmental factors dictate patterns of variation in sexual traits within and across popula- tions, and thus the action and outcome of sexual selection. This study explores patterns of inheritance, diet, age, and mate-choice copying on the expression of male sexual signals and associated female mate choice in a phenotypically diverse group of Schizo- cosa wolf spiders. Focal spiders exhibit one of two male phenotypes: 'omamented' males possess large black brushes on their fo- relegs, and 'non-ornamented' males possess no brushes. Using a quantitative genetics breeding design in a mixed population of ornamented/non-ornamented males, we found a strong genetic basis to male phenotype and female choice. We also found that some ornamented males produced some sons with large brushes and others with barely visible brushes. Results of diet manipula- tions and behavioral mating trials showed no influence of diet on male phenotype or female mate choice. Age post maturation, however, influenced mate choice, with younger females being more likely to mate with ornamented males. A mate-choice copy- ing experiment found that, following observations of another female's mate choice/copulation, virgin mature females tended to match the mate choice (ornamented vs. non-ornamented males) of the females they observed. Finally, analyses of genetic varia- tion across phenotypically pure (only one male phenotype present) vs. mixed (both phenotypes present) populations revealed ge- netic distinction between phenotypes in phenotypically-pure populations, but no distinctionin phenotypically-mixed populations. The difference in patterns of genetic differentiation and mating across geographic locations suggests a complex network of fac- tors contributing to the outcome of sexual selection .展开更多
The term 'assortative mating' has been applied to describe two very different phenomena: (1) the tendency for indi- viduals to choose phenotypically similar mates from among conspecifics; or (2) the tendency to...The term 'assortative mating' has been applied to describe two very different phenomena: (1) the tendency for indi- viduals to choose phenotypically similar mates from among conspecifics; or (2) the tendency to prefer conspecific over hete- rospecific mates (behavioral reproductive isolation). Both forms of assortative mating are widespread in nature, but the relation- ship between these behaviors remains unclear. Namely, it is plausible that a preference for phenotypically similar conspecifics in cidentally reduces the probability of mating with phenotypically divergent heterospecifics. We present a model to calculate how the level of reproductive isolation depends on intraspecific assortative mating and the phenotypic divergence between species. For empirically reasonable levels of intraspecific assortment on a single trait axis, we show that strong reproductive isolation requires very substantial phenotypic divergence. We illustrate this point by applying our model to empirical data from threespine stickleback Gasterosteus aculeatus and Darwin's Finches (Geospiza spp). We conclude that typical levels of intraspecific assortment cannot generally be extrapolated to explain levels of interspecific reproductive isolation. Instead, reproductive isolation between species likely arises from different mate choice behaviors, or multivariate assortative mating [Current Zoology 58 (3): 484-492, 2012].展开更多
基金the National Natural Foundation of China grants 40273016 , 49973013
文摘Based on studies of petrography, mineralogy and mineral chemistry, deep mantle fluids and their products in kimberlites and diamonds can be assorted into the ultradeep fluid-transmitted minerals with an oxygen-free feature, the deep fluid metasomatized-minerals characterized by enrichment in TiO2, K2O, BaO, REE and Fe3+, and the deep fluid-reformed minerals. The three types show a successive descent in fluid origin depth and metasomatism strength, and they have brought forth a series of corresponding metasomatic products.
基金This research was partially supported by the National Science Foundation of China [Grants 71401086, 71332005 and 71361130017].
文摘This paper provides an efficient and useful approach for demand estimation and assortment planning of cell phone cards in wireless communication industry. We use maximum likelihood estimation to estimate the primary demand and substitution probability of each cell phone card based on historical sales data. This estimation model is nonlinear, so we transform it to a mixed integer linear programming model by logarithmic transformations and piecewise'linear approximation. On the basis of the estimation results, we can make assortment planning. Considering the resource of cell phone cards is limited, we jointly optimize the assortment and quantity planning of cell phone cards. In numerical study, we apply our approach to a large mobile service provider in China and frod our approach can increase the revenue of this mobile service provider by 23.69%. Sensitivity analysis shows the mobile service provider should provide more assortments to increase revenue when the types of cell phone cards that can be assigned to each store are limited.
文摘With increasing varieties and products,management of limited shelf space becomes quite difficult for retailers.Hence,an efficient product assortment,which in turn helps to plan the organization of various products across limited shelf space,is extremely important for retailers.Products can be distinguished based on quality,price,brand,and other attributes,and decision needs to be made about an assortment of the products based on these attributes.An efficient assortment planning improves the financial performance of the retailer by increasing profits and reducing operational costs.Clustering techniques can be very effective in grouping products,stores,etc.and help managers solve the problem of assortment planning.This paper proposes data mining approaches for assortment planning for profit maximization with space,and cost constraints by mapping it into well-known knapsack problem.
基金supported by the Fundamental Research Funds for the Central Universities of Xiamen University(No.2072021127)Ka-Meng Nip’s research work is partially supported by the Natural Science Foundation of Fujian Province of China(No.2021J05011)the Fundamental Research Funds for the Central Universities of Xiamen University(No.20720210033).
文摘In this work,we study the conic quadratic mixed-integer formulation for assortment optimization problem under the mixture of multinomial logit(MMNL)model.The MMNL model generalizes the widely studied multinomial logit choice model and can approximate any random utility model with an arbitrary additive error.An important operational decision problem in revenue management is assortment optimization problem,which aims to find a subset of products to make available to customers that maximizes the expected revenue of the retailer.It is known that assortment optimization problem under the MMNL model is NP-hard and inapproximable within any constant performance guarantee.Commonly used methods for solving such problem are heuristical approaches or customized combinatorial optimization approaches.In the meanwhile,studies related to global optimization approaches are relatively scarce.We propose an enhanced conic quadratic mixed-integer formulation for solving assortment optimization problem under the MMNL model with a higher computational efficiency.Furthermore,we conduct extensive numerical experiments to demonstrate that the proposed reformulation significantly outperforms the existing conic reformulations for assortment optimization under the MMNL model.
文摘If assortment priee parity of Clase coking coal and its qtalty price danrcnee is nonreasonable, it deren't gulde in Anprotrig tbe quallry metaliurgical coking coal and may be influence theeconomic benefit of metallurgical enterprises. This paper propose the principles and mathematicmodel for determination aseortment party of clean cokingcoal and its quality difference of ash content in clean coking coal in order to urge wasbenes into producing superior clean coking cleal whichis under condition of consideration both interest waskeries and interest metallurgicai industry. It canbe used as a method in theory to make price strategies under condition of socialism maket economicfor washeries of clean coking coal
文摘Based on an investigation on the current situation of SPM in some enterprises, this paper presents the common probletns and poor fields existing in SPM in enterprise; analyzes the reasons which resulted in the situation, and then puts forward some feasible measures to improve it. Lastly, some fields that should be paid more attention in SPM are provided.
基金supported in part by NCET (NCET06-9-23)NUDT (JC08-02-03)
文摘An estimate of the upper bound is given for the double determinant of the sum of two arbitrary quaternion matrices, and meanwhile the lower bound on the double determinant is established especially for the sum of two quaternion matrices which form an assortive pair. As applications, some known results are obtained as corollaries and a question in the matrix determinant theory is answered completely.
基金supported by the National Natural Science Foundation of China(Grant Nos.61673150 and 11622538)Special Project for the Central Guidance on Local Science and Technology Development of Sichuan Province,China(Project No.2021ZYD0029)。
文摘In real-world networks,there usually exist a small set of nodes that play an important role in the structure and function of networks.Those vital nodes can influence most of other nodes in the network via a spreading process.While most of the existing works focused on vital nodes that can maximize the spreading size in the final stage,which we call final influencers,recent work proposed the idea of fast influencers,which emphasizes nodes’spreading capacity at the early stage.Despite the recent surge of efforts in identifying these two types of influencers in networks,there remained limited research on untangling the differences between the fast influencers and final influencers.In this paper,we firstly distinguish the two types of influencers:fast-only influencers and final-only influencers.The former is defined as individuals who can achieve a high spreading effect at the early stage but lose their superiority in the final stage,and the latter are those individuals that fail to exhibit a prominent spreading performance at the early stage but influence a large fraction of nodes at the final stage.Further experiments are based on eight empirical datasets,and we reveal the key differences between the two types of influencers concerning their spreading capacity and the local structures.We also analyze how network degree assortativity influences the fraction of the proposed two types of influencers.The results demonstrate that with the increase of degree assortativity,the fraction of the fast-only influencers decreases,which indicates that more fast influencers tend to keep their superiority at the final stage.Our study provides insights into the differences and evolution of different types of influencers and has important implications for various empirical applications,such as advertisement marketing and epidemic suppressing.
文摘It is a challenging task to investigate the different in- fluence of long-range and short-range interactions on two-state and three-state folding kinetics of protein. The networks of the 30 two-state proteins and 15 three-state proteins were constructed by complex networks analysis at three length scales: Protein Contact Networks, Long-range Interaction Networks and Short-range Interaction Networks. To uncover the relationship between structural properties and folding kinetics of the proteins, the correlations of protein network parameters with protein folding rate and topology parameters contact order were analyzed. The results show that Protein Contact Networks and Short-range Interaction Networks (for both two-state and three-state proteins) exhibit the “small-world” property and Long-range Interaction networks indicate “scale-free” behavior. Our results further indicate that all Protein Contact Networks and Short- range Interaction networks are assortative type. While some of Long-range Interaction Networks are of assortative type, the others are of disassortative type. For two-state proteins, the clustering coefficients of Short-range Interaction Networks show prominent correlation with folding rate and contact order. The assortativity coefficients of Short-range Interaction Networks also show remarkable correlation with folding rate and contact order. Similar correlations exist in Protein Contact Networks of three-state proteins. For two-state proteins, the correlation between contact order and folding rate is determined by the numbers of local contacts. Short- range interactions play a key role in determining the connecting trend among amino acids and they impact the folding rate of two-state proteins directly. For three-state proteins, the folding rate is determined by short-range and long-range interactions among residues together.
基金supported by the National Natural Science Foundation of China(No.32070452to YS)。
文摘Sex differences in plumage color are common in bird species.Some bird species are regarded as sexually monochromatic in human visual systems,and in recent years,some species are found to be of cryptic(to human)sexual dichromatism by spectrophotometric techniques.However,the functions of plumage color are still less understood in these species.Here,we focused on plumage color traits in the Chestnut Thrush(Turdus rubrocanus),which is considered as a sexually monochromatic bird by human observers.We used spectrometer analyses and avian visual modeling to investigate the color traits of males and females,and whether these color traits are involved in assortative mating.We found that Chestnut Thrush showed sexual dichromatism in bill,throat and wing,and pairs mated assortatively with colorations of throat,chest,crown and wing.We also found that color of tarsus was different between two consecutive years.These results revealed that Chestnut Thrush is sexually dichromatic in the avian visual system,and plumage color traits play important roles in mate choice.
文摘Wolbachia are a group of intracellular bacteria, ma-ternally transmitted from infected females to their offspring, which affect a wide range of arthropods. Their presence is associated with Cytoplasmic Incompatibility (CI) in crosses between infected males and uninfected females and between populations carrying different strains of Wolbachia. The negative influence of Wolbachia a infection on progeny fitness in incompatible crosses can be considered a first step in the appearance of reproductive isolation between infected and uninfected individuals. In this work, we examined the possibility of assortative mating in response to Wolbachia infection, a response that evolved as an incipient mechanism of sexual isolation in the species D. melanogaster and D. simulans. We found that the females of each species could detect the presence of the bacterium in the other sex and chose to mate with males who had the same state of infection, whereas the males randomly attempted to mate with both infected and uninfected females. Thus, Wolbachia may act as an additive factor influencing sexual isolation in Drosophila populations and may play a role in speciation events.
基金supported by the National Natural Science Foundation of China(Grant No.:71173154)the National Social Science Foundation of China(Grant No.:08BZX076)the Social Science Foundation of Tongji University(Grant No.:3850219007)
文摘Purpose: This paper tries to understand the dynamics of scientific communication systems during crises by investigating as a case study the blogging activities that took place during the period of the 2011 earthquake and related events in Japan. Interactions between bloggers and registered users are studied quantitatively and qualitatively at Sciencenet.cn, an influential science-related blogosphere in China.Design/methodology/approach: The editors of Sciencenet.cn compiled a special issue of science blog articles under the title Analysis of the Japanese Earthquake. We developed a spider program and downloaded from this special issue the metadata about title, content,publishing time, total read count, reply count and recommendation count, and further collected information about bloggers and recommenders. We then sent a short message to the bloggers who wrote articles on these emergencies, asking for their educational and professional background.Findings: We found that knowledge reflected in the blog articles is strongly related to the educational and professional background of bloggers. Knowledge diffusion is facilitated by interactions, such as recommendations, comments and answers. Interactions via comments and recommendations are of an assortative nature: A blog article is more likelyto be commented on and recommended by those bloggers who write on the same or similar topics than by those writing on a different one. Registered users tend to give comments on articles dealing with the topic that they recommend, and vice versa.Interaction in the intersection of two or three topics is more intense than that within one topic. The impact of blog articles is also influenced by other factors, such as the reputation of the blogger and the type of information they contain.Implications and limitations: It is confirmed that studying blogs is a valid approach within informetric studies. Yet, we only studied one triple(earthquake, tsunami, nuclear disaster) event based on data originating from one Chinese blog website. More events should be studied.Originality/value: Informetric studies based on blogs are still relatively few. Using science blogs and combining comments on a triple event with the knowledge background of bloggers in China is even less common. As such this contribution enhances our knowledge on this new form of science communication activity.
文摘A major component rice variety of Xiangwanxian 9 (a late Indica variety) with 13.1%, 15.6% and 18. 3% of the moisture was respectively mixed with three ad-ditive varieties in 13% of moisture at ration of 7:3 for processing assorted rices. Head rice recovery of the treatments was determined 24 hours later. Analysis indicated sig-nificant differences exist in the effects produced by the component varieties, their moistures and the component variety moisture.
基金The project supported by National Natural Science Foundation of China Under Grant Nos. 10672093, 10372054t and 70431002
文摘This paper proposes a novel complex network with assortative property based on multi-center networks. The average path length and clustering coefficient of the network are calculated, and the impact on the network topology is investigated. A simple dynamic system established on the proposed network is used to analyze how the assortative property of the network affects synchronization.
基金supported by the National Natural Science Foundation of China under Grant No.10675060
文摘For most networks, the weight of connection is changing with their attachment and inner affinity. By introducing a mixed mechanism of weighted-driven and inner selection, the model exhibits wide range power-law distributions of node strength and edge weight, and the exponent can be adjusted by not only the parameter δ but also the probability q. Furthermore, we investigate the weighted average shortest distance, clustering coefficient, and the correlation of our network. In addition, the weighted assortativity coefficient which characterizes important information of weighted topological networks has been discussed, but the variation of coefficients is much smaller than the former researches.
文摘Reproductive isolation is the basis of the Biological Species Definition and can be a driving force of speciation. Theoretical studies have provided models of how reproductive isolation can arise within individual species. Genetic tests of these models are limited to populations in which reproductive isolation is present but not complete. Here, reproductive isolation in the Elgans-Group of the nematode genus Caenorhabditis is reviewed. Pre-mating barriers, assortative fertilization and post-zygotic barriers all have been observed in this clade. In some combinations of species, fertile F1 hybrids can be obtained. Therefore, the Elegans-Group of Caenorhabditis is poised to become an important experimental system for the study of reproductive isolation.
文摘This study aims to contribute to marketing theory by applying monopolistic competition theory to investigate how differentiation affects online retailers7 pricing power. We examine the intermediary effect of customer loyalty on the relationship between differentiation and pricing power of online retailers. We assume that customers have different preferences for the differentiated characteristics of online retailers, and thus different degrees of willingness to pay premiums, which gives online retailers pricing power. Structural equation modeling (SEM) is employed to test the hypothesized relati on ships between differentiation, customer loyalty, and pricing power. The statistical results of the empirical data indicate that some of the differentiation characteristics of online retailers can cultivate their pricing power indirectly. Logistics quality followed by commodity assortment and transaction security produces profound effects on the buildup of pricing power with customer loyalty as an intermediary factor. Results further reveal that commodity quality is positively related to pricing power. This study expands the definition of differentiation by combining corporate strategic positioning with commodity pricing. Implications for practice and di recti ons for future research are provided.
文摘The extent to which sexual selection is involved in speciation with gene flow remains an open question and the sub- ject of much research. Here, we propose that some insight can be gained from considering the concept of magic traits (i.e., traits involved in both reproductive isolation and ecological divergence). Both magic traits and other, "non-magic", traits can contribute to speciation via a number of specific mechanisms. We argue that many of these mechanisms are likely to differ widely in the ex- tent to which they involve sexual selection. Furthermore, in some cases where sexual selection is present, it may be prone to in- hibit rather than drive speciation. Finally, there are a priori reasons to believe that certain categories of traits are much more ef- fective than others in driving speciation. The combination of these points suggests a classification of traits that may shed light on the broader role of sexual selection in speciation with gene flow. In particular, we suggest that sexual selection can act as a driver of speciation in some scenarios, but may play a negligible role in potentially common categories of magic traits, and may be likely to inhibit speciation in common categories of non-magic traits [Current Zoology 58 (3): 510-516, 2012].
文摘Genetic, life history, and environmental factors dictate patterns of variation in sexual traits within and across popula- tions, and thus the action and outcome of sexual selection. This study explores patterns of inheritance, diet, age, and mate-choice copying on the expression of male sexual signals and associated female mate choice in a phenotypically diverse group of Schizo- cosa wolf spiders. Focal spiders exhibit one of two male phenotypes: 'omamented' males possess large black brushes on their fo- relegs, and 'non-ornamented' males possess no brushes. Using a quantitative genetics breeding design in a mixed population of ornamented/non-ornamented males, we found a strong genetic basis to male phenotype and female choice. We also found that some ornamented males produced some sons with large brushes and others with barely visible brushes. Results of diet manipula- tions and behavioral mating trials showed no influence of diet on male phenotype or female mate choice. Age post maturation, however, influenced mate choice, with younger females being more likely to mate with ornamented males. A mate-choice copy- ing experiment found that, following observations of another female's mate choice/copulation, virgin mature females tended to match the mate choice (ornamented vs. non-ornamented males) of the females they observed. Finally, analyses of genetic varia- tion across phenotypically pure (only one male phenotype present) vs. mixed (both phenotypes present) populations revealed ge- netic distinction between phenotypes in phenotypically-pure populations, but no distinctionin phenotypically-mixed populations. The difference in patterns of genetic differentiation and mating across geographic locations suggests a complex network of fac- tors contributing to the outcome of sexual selection .
文摘The term 'assortative mating' has been applied to describe two very different phenomena: (1) the tendency for indi- viduals to choose phenotypically similar mates from among conspecifics; or (2) the tendency to prefer conspecific over hete- rospecific mates (behavioral reproductive isolation). Both forms of assortative mating are widespread in nature, but the relation- ship between these behaviors remains unclear. Namely, it is plausible that a preference for phenotypically similar conspecifics in cidentally reduces the probability of mating with phenotypically divergent heterospecifics. We present a model to calculate how the level of reproductive isolation depends on intraspecific assortative mating and the phenotypic divergence between species. For empirically reasonable levels of intraspecific assortment on a single trait axis, we show that strong reproductive isolation requires very substantial phenotypic divergence. We illustrate this point by applying our model to empirical data from threespine stickleback Gasterosteus aculeatus and Darwin's Finches (Geospiza spp). We conclude that typical levels of intraspecific assortment cannot generally be extrapolated to explain levels of interspecific reproductive isolation. Instead, reproductive isolation between species likely arises from different mate choice behaviors, or multivariate assortative mating [Current Zoology 58 (3): 484-492, 2012].