A New Revocable and Re-Delegable Proxy Signature and Its Application

With the popularity of cloud computing and mobile Apps, on-demand services such as on-line music or audio streaming and vehicle booking are widely available nowadays. In order to allow efficient delivery and management of the services, for large-scale on-demand systems, there is usually a hierarchy where the service provider can delegate its service to a top-tier （e.g., countrywide） proxy who can then further delegate the service to lower level （e.g., region-wide） proxies. Secure （re-）delegation and revocation are among the most crucial factors for such systems. In this paper, we investigate the practical solutions for achieving re-delegation and revocation utilizing proxy signature. Although proxy signature has been extensively studied in the literature, no previous solution can achieve both properties. To fill the gap, we introduce the notion of revocable and re-delegable proxy signature that supports efficient revocation and allows a proxy signer to re-delegate its signing right to other proxy signers without the interaction with the original signer. We define the formal security models for this new primitive and present an efficient scheme that can achieve all the security properties. We also present a secure on-line revocable and re-delegate vehicle ordering system （RRVOS） as one of the applications of our proposed scheme.

Assessment of the cytotoxic and mutagenic potential of the Jialu River and adjacent groundwater using human-hamster hybrid cells

The Jialu River in China has been seriously polluted by the direct discharge of industrial and domestic wastewater. The predominant contaminants of the Jialu River and its adjacent groundwater were recently investigated. However, the potential genotoxic impact of polluted water on human health remains to be clarified. Here, we used human–hamster hybrid（AL） cells, which are sensitive for detecting environmental mutagens. We found that the cytotoxicity and mutagenicity of the groundwater in the Jialu River basin were influenced by the infiltration of the Jialu River. Hydrological periods significantly affected the cytotoxicity, but not the mutagenic potential, of surface and groundwater. Further, the mutagenic potential of groundwater samples located 〈 1 km from the Jialu River（S（M-2） water samples） was detected earlier than that of groundwater samples located approximately 20 km from the Jialu River（SN water samples）. Because of high cytotoxicity, the mutagenic potential of water samples from the Jialu River（S（M-1） water samples） was not significantly enhanced compared with that of untreated controls. To further assess the mutagenic dispersion potential, an artificial neural network model was adopted. The results showed that the highest mutagenic potential of groundwater was observed approximately 10 km from the Jialu River. Although further investigation of mutagenic spatial dispersion is required, our data are significant for advancing our understanding of the origin, dispersion,and biological effects of water samples from polluted areas.

Enhanced radiosensitivity by 6-thio-dG via increasing telomere dysfunction and ataxia telangiectasia mutated inhibition in non-small cell lung cancer

Objective:To investigate the radiosensitivity of 6-thio-dG and its underlying molecular mechanisms in non-small cell lung cancer(NSCLC).Methods:H1299 and A549 NSCLC cells were pretreated with 6-thio-dG for one week and then exposed toγ-irradiation.Cell proliferation and survival were quantified using clonogenic assays.DNA damage was assessed using immunofluorescence forγH2AX.Telomere dysfunction-induced foci analysis was performed by the colocalization of telomere signals(FISH)andγH2AX.Telomere fusion was defined as two telomere signals merged into one at the chromosome by immuno-FISH in metaphase spreads.Proteins related to the DNA damage response were detected using Western blot analysis.Apoptosis wasanalyzed using flow cytometry and Western blot.Results:The presence of 6-thio-dG increased the radio sensitivity of H1299 and A549 cells(P<0.05),but had no effect on the normal human lung fibroblast line,MRC5.6-thio-dG pretreatment significantly reduced the clonogenic potential induced byγ-ray irradiation and aggravated genomic DNA and telomeric DNA damage(P<0.05).In addition,6-thio-dG pretreatment effectively increasedγ-ray irradiation induced telomere dysfunction(P<0.05),resulting in disruption of chromosome stability and inhibition of the ATM pathway,thereby impairing genomic DNA and telomeric DNA repair,which was closely associated with enhanced drug-mediated radiation-induced apoptosis.Conclusions:6-thio-dG increases the radiosensitivity of NSCLC by inhibiting ATM and inducing telomere dysfunction,which can potentially be used as a strategy for radiotherapy for NSCLC.