In order to inhibit Free Riding in Peer-toPeer(P2P) file-sharing systems,the Free Riding Inhibition Mechanism Based on User Behavior(IMBUB) is proposed.IMBUB considers the regularity of user behavior and models user b...In order to inhibit Free Riding in Peer-toPeer(P2P) file-sharing systems,the Free Riding Inhibition Mechanism Based on User Behavior(IMBUB) is proposed.IMBUB considers the regularity of user behavior and models user behavior by analyzing many definitions and formulas.In IMBUB,Bandwidth Allocated Ratio,Incentive Mechanism Based on User Online Time,Double Reward Mechanism,Incentive Mechanism of Sharing for Permission and Inhibition Mechanism of White-washing Behavior are put forward to inhibit Free Riding and encourage user sharing.A P2P file system BITShare is designed and realized under the conditions of a campus network environment.The test results show that BITShare's Query Hit Ratio has a significant increase from 22% to 99%,and the sharing process in BITShare is very optimistic.Most users opt to use online time to exchange service quality instead of white-washing behavior,and the real white-ishing ratio in BITShare is lower than 1%.We confirm that IMBUB can effectively inhibit Free Riding behavior in P2P file-sharing systems.展开更多
Mycobacterium tuberculosis(M.tb) and human immunodeficiency virus(HIV) co-infection has become a public health issue worldwide. Up to now, there have been many unresolved issues either in the clinical diagnosis and tr...Mycobacterium tuberculosis(M.tb) and human immunodeficiency virus(HIV) co-infection has become a public health issue worldwide. Up to now, there have been many unresolved issues either in the clinical diagnosis and treatment of M.tb/HIV coinfection or in the basic understanding of the mechanisms for the impairments to the immune system by interactions of these two pathogens. One important reason for these unsolved issues is the lack of appropriate animal models for the study of M.tb/HIV coinfection. This paper reviews the recent development of research on the animal models of M.tb/HIV co-infection, with a focus on the non-human primate models.展开更多
Aims Diversity in communities is determined by species’ability to coexist with each other and to overcome environmental stress that may act as an environmental filter.Niche differentiation(ND)results in stronger intr...Aims Diversity in communities is determined by species’ability to coexist with each other and to overcome environmental stress that may act as an environmental filter.Niche differentiation(ND)results in stronger intra-than interspecific competition and promotes coexistence.Because stress affects interactions,the strength of ND may change along stress gradients.A greater diversity of plant growth forms has been observed in stressful habitats,such as deserts and alpine regions,suggesting greater ND when stress is strong.We tested the hypothesis that niche differences and environmental filters become stronger with stress.Methods In a semiarid grassland in southern Mexico,we sowed six annual species in the field along a hydric stress gradient.Plants were grown alone(without interactions),with conspecific neighbors(intraspecific interactions)or with heterospecific neighbors(interspecific interactions).We analyzed how the ratio of intra-to interspecific competition changed along the gradient to assess how water availability determines the strength of ND.We also determined if hydric stress represented an environmental filter.Important Findings We observed stronger intra-than interspecific competition,especially where hydric stress was greater.Thus,we found ND in at least some portion of the gradient for all but one species.Some species were hindered by stress,but others were favored by it perhaps because it eliminates soil pathogens.Although strong ND was slightly more frequent with stress,our species sample was small and there were exceptions to the general pattern,so further research is needed to establish if this is a widespread phenomenon in nature.展开更多
基金This work was partly supported by 2012 Outstanding Talents Project of Beijing Organization Department under Grant No.2012D00501700005，Science and Technology Project of Beijing Municipal Education Commission under Grant No.KM201110016006，National Natural Science Foundation of China under Grant No.61100205
文摘In order to inhibit Free Riding in Peer-toPeer(P2P) file-sharing systems,the Free Riding Inhibition Mechanism Based on User Behavior(IMBUB) is proposed.IMBUB considers the regularity of user behavior and models user behavior by analyzing many definitions and formulas.In IMBUB,Bandwidth Allocated Ratio,Incentive Mechanism Based on User Online Time,Double Reward Mechanism,Incentive Mechanism of Sharing for Permission and Inhibition Mechanism of White-washing Behavior are put forward to inhibit Free Riding and encourage user sharing.A P2P file system BITShare is designed and realized under the conditions of a campus network environment.The test results show that BITShare's Query Hit Ratio has a significant increase from 22% to 99%,and the sharing process in BITShare is very optimistic.Most users opt to use online time to exchange service quality instead of white-washing behavior,and the real white-ishing ratio in BITShare is lower than 1%.We confirm that IMBUB can effectively inhibit Free Riding behavior in P2P file-sharing systems.
基金supported by grants from the National Natural Sciences Foundation of China(81201261,81301428)the National Science Foundation for Post-doctoral Scientists of China(2013M5317456)the National Science and Technology Major Project of the Ministry of Science and Technology of China(2012ZX10004501-001-004)
文摘Mycobacterium tuberculosis(M.tb) and human immunodeficiency virus(HIV) co-infection has become a public health issue worldwide. Up to now, there have been many unresolved issues either in the clinical diagnosis and treatment of M.tb/HIV coinfection or in the basic understanding of the mechanisms for the impairments to the immune system by interactions of these two pathogens. One important reason for these unsolved issues is the lack of appropriate animal models for the study of M.tb/HIV coinfection. This paper reviews the recent development of research on the animal models of M.tb/HIV co-infection, with a focus on the non-human primate models.
基金supported by the Dirección General de Asuntos del Personal Académico,Universidad Nacional Autónoma de México(IN212618).
文摘Aims Diversity in communities is determined by species’ability to coexist with each other and to overcome environmental stress that may act as an environmental filter.Niche differentiation(ND)results in stronger intra-than interspecific competition and promotes coexistence.Because stress affects interactions,the strength of ND may change along stress gradients.A greater diversity of plant growth forms has been observed in stressful habitats,such as deserts and alpine regions,suggesting greater ND when stress is strong.We tested the hypothesis that niche differences and environmental filters become stronger with stress.Methods In a semiarid grassland in southern Mexico,we sowed six annual species in the field along a hydric stress gradient.Plants were grown alone(without interactions),with conspecific neighbors(intraspecific interactions)or with heterospecific neighbors(interspecific interactions).We analyzed how the ratio of intra-to interspecific competition changed along the gradient to assess how water availability determines the strength of ND.We also determined if hydric stress represented an environmental filter.Important Findings We observed stronger intra-than interspecific competition,especially where hydric stress was greater.Thus,we found ND in at least some portion of the gradient for all but one species.Some species were hindered by stress,but others were favored by it perhaps because it eliminates soil pathogens.Although strong ND was slightly more frequent with stress,our species sample was small and there were exceptions to the general pattern,so further research is needed to establish if this is a widespread phenomenon in nature.
