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Large-scale deployments of mission-critical services have led to stringent demands on Internet routing, but frequently occurring network failures can dramatically degrade the network performance. However, Border Gateway Protocol (BGP) can not react quickly to recover from them. Although extensive research has been conducted to deal with the problem, the multiple failure scenarios have never been properly addressed due to the limit of distributed control plane. In this paper, we propose a local fast reroute approach to effectively recover from multiple link failures in one administrative domain. The principle of Software Defined Networking (SDN) is used to achieve the software defined AS-level fast rerouting. Considering AS relationships, efficient algorithms are proposed to automatically and dynamically find protection paths for multiple link failures; then OpenFlow forwarding rules are installed on routers to provide data forwarding continuity. Our approach is able to ensure applicability to ASes with flexibility and adaptability to multiple link failures, contributing toward improving the network performance. Through experimental results, we show that our proposal provides effective failure recovery and does not introduce significant control overhead to the network.

A 3 125 bp cellulose synthase gene, PtoCesA1, which has a 98% identity to PtrCesA1 from Populus tremuloides, was cloned from cDNA prepared from secondary xylem of P. tomentosa. Four anti-expression vectors with different fragments of PtoCesA1, named as pBIPF, pBICC1, pBIPR and pBIBR, were constructed. Some traits of transformed tobacco of pBICC1, pBIPR and pBIBR differed from wild types, such as small leaves, “dwarf” phenotype and thinner xylem and fiber cell walls than wild plants consistent with a loss of cellulose. It indicated that the growth of transgenic tobacco was restrained by the expression of anti-PtoCesA1. Transgenic tobacco was obtained and the contents of cellulose and lignin were analyzed as well as the width and length of fiber cells, and xylem thickness for both transgenic and control plants. Transformed tobacco showed a different phenotype from control plants and it implied that PtoCesA1 was essential for the cellulose biosynthesis in poplar stems.

Due to the inherent design faults of the Border Gateway Protocol (BGP), BGP prefix hijacking remains a serious security threat to the Internet routing system. AS hijacking enables an attacker to pass the prefix ownership validation mechanism, it is more sophisticated than IP prefix hijacking. So far, many efforts have been done on the detection of prefix hijacking, however, AS hijacking has not received enough attention. This paper presents a system that is capable of detecting AS hijacking inside one administrative domain before they pollute a large number of external Autonomous Systems (ASes) on the Internet. Experiment results show that our proposed system can detect AS hijacking attacks with high accuracy and low detection latency. Furthermore, it is suitable for incremental deployment.

Radon concentrations were measured at different locations in a house using CSR solid track detectors with and without electret. The results show that radon concentrations differ even in the same room; in the middle of the room, they decrease with increasing height from the floor. Radon concentrations at the height of 0.88 m (i.e. about the breathing height when the resident is sleeping) are about 1.3-1.5 times that at 0.5 m below the ceiling. They are the highest at the head of a bed close to the wall where the sleeper's head usually lies, viz. 1.6- 1.8 times that at 0.5 m below the ceiling. The radiation dose to the inhabitants, estimated in accordance with the average radon concentration measured at the 0.5 m location below the celling, should therefore be multiplied by a correction factor of about 1.5 to obtain the realistic dose.

This paper reports the measured results of radon concentration in different environments with CSR solid track detectors. The rd-sults show that the radon concentrations are 15.6 Bq m -3 for ordinary buildings; 28.5, 31.6 and 71.1 Bq m -3 for the houses made of A,B and C types of coal-cinder-brick buildings rdspectively, and 36.1, 43.6 and 85.6 Bq m -3 indoors in residential quarters around Chengxi coal mine and near two uranium mines.

This paper reports the measured results of radon concentrations at different positions of a house with CSR solid track detector with and without electret. The results show that the radon concentration is different positions of even the same room, it is the highest at end of a bed close to the wall, where his/her head usually is when the resident is on bed, being 1.6-1.8 times that at the position 0.5 m below the ceiling, and that at the middle of the room the radon concentration is decreasing with increasing height from the floor, the radon concentration at the height of 0.88 m is about 1.3-1.5 times that of 2.4 m (0.5 m below the ceiling). Based on the investigation, the radiation dose to the residents estimated in accordance with the average measured radon concentration at the location 0.5 m below the ceiling should be multiplied by a correction factor of about 1.5 to obtain the realistic dose.