New challenges are introduced when people try to build a general-purpose mobile agent middleware in Grid envi- ronment. In this paper, an instance-oriented security mechanism is proposed to deal with possible security...New challenges are introduced when people try to build a general-purpose mobile agent middleware in Grid envi- ronment. In this paper, an instance-oriented security mechanism is proposed to deal with possible security threats in such mobile agent systems. The current security support in Grid Security Infrastructure (GSI) requires the users to delegate their privileges to certain hosts. This host-oriented solution is insecure and inflexible towards mobile agent applications because it cannot prevent delegation abuse and control well the diffusion of damage. Our proposed solution introduces security instance, which is an en- capsulation of one set of authorizations and their validity specifications with respect to the agent’s specific code segments, or even the states and requests. Applications can establish and configure their security framework flexibly on the same platform, through defining instances and operations according to their own logic. Mechanisms are provided to allow users delegating their identity to these instances instead of certain hosts. By adopting this instance-oriented security mechanism, a Grid-based general-purpose MA middleware, Everest, is developed to enhance Globus Toolkit’s security support for mobile agent applications.展开更多
The application of Penman's method of cell fractionation to plant protoplasts leads to our finding of keratin intermediate filament(IF)-like system in maize protoplasts,which was identified by using immunogold lab...The application of Penman's method of cell fractionation to plant protoplasts leads to our finding of keratin intermediate filament(IF)-like system in maize protoplasts,which was identified by using immunogold labelling with monoclonal antibody of cytokeratin from animal cells.Many gold particles were found to be bound on filaments,linked by 3 nm filaments.After further digestion and extraction with DNase I and ammonium sulphate.IF-like framework-lamina-nuclear matrix system was shown under electron microscope.That IF system exists in plant protoplasts just like in animal cells,and their main component is keratin-like protein.展开更多
基金Project (No. 602032) supported by the Natural Science Foundationof Zhejiang Province, China
文摘New challenges are introduced when people try to build a general-purpose mobile agent middleware in Grid envi- ronment. In this paper, an instance-oriented security mechanism is proposed to deal with possible security threats in such mobile agent systems. The current security support in Grid Security Infrastructure (GSI) requires the users to delegate their privileges to certain hosts. This host-oriented solution is insecure and inflexible towards mobile agent applications because it cannot prevent delegation abuse and control well the diffusion of damage. Our proposed solution introduces security instance, which is an en- capsulation of one set of authorizations and their validity specifications with respect to the agent’s specific code segments, or even the states and requests. Applications can establish and configure their security framework flexibly on the same platform, through defining instances and operations according to their own logic. Mechanisms are provided to allow users delegating their identity to these instances instead of certain hosts. By adopting this instance-oriented security mechanism, a Grid-based general-purpose MA middleware, Everest, is developed to enhance Globus Toolkit’s security support for mobile agent applications.
文摘The application of Penman's method of cell fractionation to plant protoplasts leads to our finding of keratin intermediate filament(IF)-like system in maize protoplasts,which was identified by using immunogold labelling with monoclonal antibody of cytokeratin from animal cells.Many gold particles were found to be bound on filaments,linked by 3 nm filaments.After further digestion and extraction with DNase I and ammonium sulphate.IF-like framework-lamina-nuclear matrix system was shown under electron microscope.That IF system exists in plant protoplasts just like in animal cells,and their main component is keratin-like protein.
