Security Defense of Large Scale Networks Under False Data Injection Attacks: An Attack Detection Scheduling Approach

In large scale networks, communication links between nodes are easily injected with false data by adversaries, so this paper proposes a novel security defense strategy to ensure the security of the network from the perspective of attack detection scheduling. Compared with existing attack detection methods, the attack detection scheduling strategy in this paper only needs to detect half of the neighbor node information to ensure the security of the node local state estimation. We first formulate the problem of selecting the sensor to be detected as a combinatorial optimization problem, which is Nondeterminism Polynomial hard (NP-hard). To solve the above problem, we convert the objective function into a submodular function. Then, we propose an attack detection scheduling algorithm based on sequential submodular maximization, which incorporates expert problem to better cope with dynamic attack strategies. The proposed algorithm can run in polynomial time with a theoretical lower bound on the optimization rate. In addition, the proposed algorithm can guarantee the security of the whole network under two kinds of insecurity conditions from the perspective of the augmented estimation error. Finally, a numerical simulation of the industrial continuous stirred tank reactor verifies the effectiveness of the developed approach

Population Diversity of Odontotermes formosanus (Shiraki) (Termitidae, Macrotermitinae) from Different Geographic Locations in Anhui Province, China

Genetic differentiation, genetic exchange, and influence of natural geographic barrier on the genetic structure of 20 geo-populations of Odontotermes formosanus sampled from different regions in Anhui province, China were detected using ISSR. Seventy-nine polymorphic loci were detected with nine ISSR primers, and the percentage of polymorphic bands was 87.78%. The average number of alleles per locus was 1.8778 ± 0.3294, and the effective number of alleles was 1.4741 ± 0.3438. The Nei′s gene diversity and Shannon information index were 0.2832 ± 0.1696 and 0.4307 ± 0.2274, respectively. All the populations were divided into two groups through UPGMA clustering analysis based on Nei’s genetic distance. One group comprised geo-populations A, C, and J, and the other group consisted of the remaining clusters. Mantel test results revealed no significant correlation between genetic similarity and geographical distance, as well as between elevation. High levels of genetic diversity, genetic mutation, and genetic differentiation were also detected among the geo-populations of O. formosanus. This study revealed the gene flow and possible migration paths of O. formosanus, which are necessary for continuous monitoring and prevention of this species

Protective Effects of Squid Ink Extract Towards Hemopoietic Injuries Induced by Cyclophosphamine

To investigate the protective effects of squid ink in chemotherapy, BALB/c mice were used as animal models of injuries induced by cyclophosphamine, a well known chemotherapeutic drug. The mice were randomly divided into five groups with the same number of males and females in each group. At the end of the experiment, animals were sacrificed to investigate organ indexes and antioxidant ability of the spleen, peripheral blood profile and quantities of bone marrow nucleated cells. Results showed that the hemopoietic function of mice was injured by cyclophosphamine, as indicated by decreases of contents of erythrocytes, leukocytes, hemoglobin and bone marrow nucleated cells (P<0.01), while platelets were not affected (P>0.05), as well as modification of organ indexes (P<0.05) and spleen antioxidant ability (P<0.05 or P<0.01), whereas sepia extract markedly increased the levels of erythrocytes, leukocytes, hemoglobin and bone marrow nucleated cells (P<0.01), but not platelets (P>0.05), and reversed the effects of cyclophosphamine on organ indexes and antioxidant ability of spleen (P<0.01 or P<0.05). In addition, squid ink extract did not change marrow hemopoiesis but improved the antioxidant ability of spleen in the animals. The data suggest that squid ink extract can protect the hemopoietic system from chemotherapeutic injury and could be employed to develop cell-protective drugs for use in clinical treatment of tumours

G-quadruplex formation in human telomeric (TTAGGG)4 sequence with complementary strand in close vicinity under molecularly crowded condition

Chromosomes in vertebrates are protected at both ends by telomere DNA composed of tandem (TTAGGG)n repeats. DNA replication produces a blunt-ended leading strand telomere and a lagging strand telomere carrying a single-stranded G-rich overhang at its end. The G-rich strand can form G-quadruplex structure in the presence of K+ or Na+. At present, it is not clear whether quadruplex can form in the double-stranded telomere region where the two complementary strands are constrained in close vicinity and quadruplex formation, if possible, has to compete with the formation of the conventional Watson–Crick duplex. In this work, we studied quadruplex formation in oligonucleotides and double-stranded DNA containing both the G- and C-rich sequences to better mimic the in vivo situation. Under such competitive condition only duplex was observed in dilute solution containing physiological concentration of K+. However, quadruplex could preferentially form and dominate over duplex structure under molecular crowding condition created by PEG as a result of significant quadruplex stabilization and duplex destabilization. This observation suggests quadruplex may potentially form or be induced at the blunt end of a telomere, which may present a possible alternative form of structures at telomere ends