Physical layer security jamming : Theoretical limits and practical designs in wireless networks

Physical layer security has been recently recognized as a promising new design paradigm to provide security in wireless networks. In addition to the existing conventional cryptographic methods, physical layer security exploits the dynamics of fading channels to enhance secured wireless links. In this approach, jamming plays a key role by generating noise signals to confuse the potential eavesdroppers, and significantly improves quality and reliability of secure communications between legitimate terminals. This article presents theoretical limits and practical designs of jamming approaches for physical layer security. In particular, the theoretical limits explore the achievable secrecy rates of user cooperation based jamming whilst the centralized, and game theoretic based precoding techniques are reviewed for practical implementations. In addition, the emerging wireless energy harvesting techniques are exploited to harvest the required energy to transmit jamming signals. Future directions of these approaches, and the associated research challenges are also briefly outlined

Physical layer security jamming: Theoretical limits and practical designs in wireless networks

Physical layer security has been recently recognized as a promising new design paradigm to provide security in wireless networks. In addition to the existing conventional cryptographic methods, physical layer security exploits the dynamics of fading channels to enhance secured wireless links. In this approach, jamming plays a key role by generating noise signals to confuse the potential eavesdroppers, and significantly improves quality and reliability of secure communications between legitimate terminals. This article presents theoretical limits and practical designs of jamming approaches for physical layer security. In particular, the theoretical limits explore the achievable secrecy rates of user cooperation based jamming whilst the centralized, and game theoretic based precoding techniques are reviewed for practical implementations. In addition, the emerging wireless energy harvesting techniques are exploited to harvest the required energy to transmit jamming signals. Future directions of these approaches, and the associated research challenges are also briefly outlined

Impaired directed forgetting in abstinent heroin addicts

Drug-related memories persist long into abstinence and are potent elicitors of drug craving and relapse. We report two experiments examining whether heroin-dependent individuals are impaired in intentionally suppressing drug-related memories. Experiment 1 adopted the Item paradigm where addicts and healthy controls were presented with a list of words each followed by a remember or forget cue. Experiment 2 adopted the List paradigm where they studied one list of items and were then split into a remember group and a forget group. Both groups studied a second list, except that the forget group was told to forget the first list. Compared with controls, addicts showed a reduced directed forgetting effect in the Item method and a total absence of one measure of directed forgetting in the List method (List 2 benefits). Results indicate that heroin addicts are impaired in directed forgetting and that the deficits are likely associated with memory encoding as opposed to retrieval. Possible problems include reduced ability in actively suppressing/stopping encoding of irrelevant information into memory or inability in changing/resetting encoding strategies. In neither experiment did the addicts show any differential directed forgetting effects between drug-related words and neutral words, indicating the generic nature of their intentional forgetting deficits

Genetic diversity of Plasmodium vivax population in Anhui province of China

Fogarty International Center of the National Institutes of Health [R01TW008151]; Divisions of Intramural Research at the National Institute of Allergy and Infectious Diseases, National Institutes of Health; State Bureau of Foreign Experts and Ministry of Education of China [B12003]; "111 Project"Background: Although the numbers of malaria cases in China have been declining in recent years, outbreaks of Plasmodium vivax malaria were still being reported in rural areas south of the Yellow River. To better understand the transmission dynamics of P. vivax parasites in China, the extent of genetic diversity of P. vivax populations circulating in Bozhou of Anhui province of China were investigated using three polymorphic genetic markers: merozoite surface proteins 1 and 3 alpha (pvmsp-1 and pvmsp-3 alpha) and circumsporozoite protein (pvcsp). Methods: Forty-five P. vivax clinical isolates from Bouzhou of Anhui province were collected from 2009 to 2010 and were analysed using PCR/RFLP or DNA sequencing. Results: Seven and six distinct allelic variants were identified using PCR/RFLP analysis of pvmsp-3 alpha with HhaI and AluI, respectively. DNA sequence analysis of pvmsp-1 (variable block 5) revealed that there were Sal-I and recombinant types but not Belem type, and seven distinct allelic variants in pvmsp-1 were detected, with recombinant subtype 2 (R2) being predominant (66.7%). All the isolates carried pvcsp with VK210 type but not VK247 or P. vivax-like types in the samples. Sequence analysis of pvcsp gene revealed 12 distinct allelic variants, with VK210-1 being predominant (41.5%). Conclusions: The present data indicate that there is some degree of genetic diversity among P. vivax populations in Anhui province of China. The genetic data obtained may assist in the surveillance of P. vivax infection in endemic areas or in tracking potential future disease outbreak