In order to assess the effect of enhancement release of chum salmon(Oncorhynchus keta),otolith strontium(Sr)marking method was used to tag chum salmon released in Tangwang River in 2016.The homing chum salmon were det...In order to assess the effect of enhancement release of chum salmon(Oncorhynchus keta),otolith strontium(Sr)marking method was used to tag chum salmon released in Tangwang River in 2016.The homing chum salmon were detected and the samples were collected in Tangwang River,Ussuri River and Suifen River in the autumn of2018.The samples were analyzed by examining Sr and calcium(Ca)fingerprints in the otolith using electron probe microanalysis.The results suggested that two samples collected in Tangwang River had the marking ring near the core of otolith where the Sr concentration and Sr/Ca ratio were significantly higher than comparative samples.Proving that the two fish belonged to the released population in Tangwang River in 2016.This article indicated the success of the enhancement release of chum salmon from the Tangwang River for the first time and also confirmed the validity of Sr marking in enhancement release of fishes.展开更多
We estimated the proportion of hatchery and natural fall spawning chum salmon returning to the Amur River using chemical markers specific to hatchery-origin fry.We used otolith microchemistry technique to identify fis...We estimated the proportion of hatchery and natural fall spawning chum salmon returning to the Amur River using chemical markers specific to hatchery-origin fry.We used otolith microchemistry technique to identify fish with artificial origin among returning spawners.First,we found that juveniles of artificial origin had higher values of the Sr:Ca molar ratio of the otoliths’edge zone compared with juveniles of natural origin,what can be related to the use of rearing feed produced from raw materials of marine origin rich in strontium.Then we observed that most of the spawners from Anyuisky Hatchery and from the Amur River mouth at the start of the spawning migration has also the higher value of Sr:Ca molar ratio of the juvenile zone of otoliths.Also,adults with higher values of the Sr:Ca molar ratio are characterized by a skewed right in the peak of the age distribution.Both,the age structure and phenological shift in the time of spawning migration of individuals with higher value of the used chemical marker corresponds to results of studies on hatchery-produced chum salmon completed at different parts on Northern Pacific.The results of this study will be used in the management of Amur fall chum salmon fisheries,and also demonstrates the necessity of the development of specific measures for increasing the survival of juvenile anadromous salmonids released at large rivers and exposed to prolonged freshwater migration to the ocean.As a further application of the methodology,we plan to identify the markers specific to each of the hatcheries and main spawning tributaries belonging to Amur River catchments.This will be an important step in the evaluation of the contribution of different stocks in mixed fisheries and also in the estimation of the effect of hatchery releases on naturally spawning stocks of Amur fall chum.Following to,our results may indicate the applicability of this approach for the determination of artificial-origin fish in a mixed sample of the Amur fall chum salmon.展开更多
This article analyses on why China Mobile and China Unicom have chosen price war rather than tacit collusion these years. On the basis of the analysis on factors that influence tacit collusion, and combined with the f...This article analyses on why China Mobile and China Unicom have chosen price war rather than tacit collusion these years. On the basis of the analysis on factors that influence tacit collusion, and combined with the facts of wireless communication market, the author suggests that the market asymmetries, cost asymmetries, and product differentiation are the basic factors, which trigger price competition between the Chinese wireless operators. By constructing a game model based on Chum rate, this article discusses how these factors cause a fight between the operators and how vigorous the price competition will be. At last, the author suggests that to keep vigor in this industry, continuous structural adjustment is essential. Besides, the number portability policies may cause tacit collusion.展开更多
Characterizing the features of user churn is crucial to the sustainable development of peer-to-peer （P2P） systems where peers join and leave at any arbitrary time. This paper analyzes the user churn in a P2P downloa...Characterizing the features of user churn is crucial to the sustainable development of peer-to-peer （P2P） systems where peers join and leave at any arbitrary time. This paper analyzes the user churn in a P2P downloading system named QQXuanfeng by using the fine-grained log analysis over 60 days. It shows that the online and offline duration is related to up （arrive） time and down （depart） time respectively. A continuous ON/OFF process, which exhibits the diurnal patterns of users, is simulated using the churn model. In particular, the dynamic departure rate is proposed to give insight into the distribution of online duration. Further more, considering the heterogeneity of users, we cluster users based on the similarity of redefined user availability. As an example of application of this model, a high availability overlay is constructed and evaluated based on the clustering.展开更多
基金The Natural Science Foundation of Heilongjiang Province of China under contract No.YQ2019C034the Special Financial Funds of the Ministry of Agriculture and Rural Affairs under contract No.2130135。
文摘In order to assess the effect of enhancement release of chum salmon(Oncorhynchus keta),otolith strontium(Sr)marking method was used to tag chum salmon released in Tangwang River in 2016.The homing chum salmon were detected and the samples were collected in Tangwang River,Ussuri River and Suifen River in the autumn of2018.The samples were analyzed by examining Sr and calcium(Ca)fingerprints in the otolith using electron probe microanalysis.The results suggested that two samples collected in Tangwang River had the marking ring near the core of otolith where the Sr concentration and Sr/Ca ratio were significantly higher than comparative samples.Proving that the two fish belonged to the released population in Tangwang River in 2016.This article indicated the success of the enhancement release of chum salmon from the Tangwang River for the first time and also confirmed the validity of Sr marking in enhancement release of fishes.
基金support of the grant of the Ministry of Science and Higher Education of the Russian Federation project No.2019-0858"Biogeochemical and geochemical studies of landscapes in the conditions of the development of mineral deposits,the search for new methods of monitoring and forecasting the State of the environment".
文摘We estimated the proportion of hatchery and natural fall spawning chum salmon returning to the Amur River using chemical markers specific to hatchery-origin fry.We used otolith microchemistry technique to identify fish with artificial origin among returning spawners.First,we found that juveniles of artificial origin had higher values of the Sr:Ca molar ratio of the otoliths’edge zone compared with juveniles of natural origin,what can be related to the use of rearing feed produced from raw materials of marine origin rich in strontium.Then we observed that most of the spawners from Anyuisky Hatchery and from the Amur River mouth at the start of the spawning migration has also the higher value of Sr:Ca molar ratio of the juvenile zone of otoliths.Also,adults with higher values of the Sr:Ca molar ratio are characterized by a skewed right in the peak of the age distribution.Both,the age structure and phenological shift in the time of spawning migration of individuals with higher value of the used chemical marker corresponds to results of studies on hatchery-produced chum salmon completed at different parts on Northern Pacific.The results of this study will be used in the management of Amur fall chum salmon fisheries,and also demonstrates the necessity of the development of specific measures for increasing the survival of juvenile anadromous salmonids released at large rivers and exposed to prolonged freshwater migration to the ocean.As a further application of the methodology,we plan to identify the markers specific to each of the hatcheries and main spawning tributaries belonging to Amur River catchments.This will be an important step in the evaluation of the contribution of different stocks in mixed fisheries and also in the estimation of the effect of hatchery releases on naturally spawning stocks of Amur fall chum.Following to,our results may indicate the applicability of this approach for the determination of artificial-origin fish in a mixed sample of the Amur fall chum salmon.
文摘This article analyses on why China Mobile and China Unicom have chosen price war rather than tacit collusion these years. On the basis of the analysis on factors that influence tacit collusion, and combined with the facts of wireless communication market, the author suggests that the market asymmetries, cost asymmetries, and product differentiation are the basic factors, which trigger price competition between the Chinese wireless operators. By constructing a game model based on Chum rate, this article discusses how these factors cause a fight between the operators and how vigorous the price competition will be. At last, the author suggests that to keep vigor in this industry, continuous structural adjustment is essential. Besides, the number portability policies may cause tacit collusion.
基金supported by the National Natural Science Foundation of China (61271199)the Fundamental Research Funds in Beijing Jiaotong University (W11JB00630)
文摘Characterizing the features of user churn is crucial to the sustainable development of peer-to-peer （P2P） systems where peers join and leave at any arbitrary time. This paper analyzes the user churn in a P2P downloading system named QQXuanfeng by using the fine-grained log analysis over 60 days. It shows that the online and offline duration is related to up （arrive） time and down （depart） time respectively. A continuous ON/OFF process, which exhibits the diurnal patterns of users, is simulated using the churn model. In particular, the dynamic departure rate is proposed to give insight into the distribution of online duration. Further more, considering the heterogeneity of users, we cluster users based on the similarity of redefined user availability. As an example of application of this model, a high availability overlay is constructed and evaluated based on the clustering.
