2,425 research outputs found

    Deceptive security based on authentication profiling

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    Passwords are broken. Multi-factor Authentication overcomes password insecurities, but its potentials are often not realised. This article presents InSight, a system to actively identify perpetrators by deceitful adaptation of the accessible system resources using Multi-factor Authentication profiles. This approach improves authentication reliability and attributes users by computing trust scores against profiles. Based on this score, certain functionality is locked, unlocked, buffered, or redirected to a deceptive honeypot, which is used for attribution. The novelty of this approach is twofold; a profile-based multi-factor authentication approach that is combined with a gradient, deceptive honeypot

    Investigations on the gut microbiota of salmonids and the applications of probiotics-based feed additives

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    A series of investigations were conducted in order to characterise the GIT microbiota of salmonids and to determine the effect of microbial modulating feed additives on the intestinal microbiota, immunity and growth of salmonids. The first experiment, Chapter three, used PCR-DGGE and 16S rRNA gene sequence analysis of cultivable bacteria were used to investigate the GIT microbiota of brown trout. 16S rRNA gene sequence analysis demonstrated that Citrobacter freundii and Carnobacterium maltaromaticum were the predominant culturable viable bacteria and lactic acid bacteria, respectively in all regions of the GIT. DGGE revealed complex communities with a diverse range of microbes from the Firmicutes and Proteobacteria phyla. The latter chapters focused not only identifying the gut microbiota of salmonids, but also on the ability of probiotics and prebiotics to modulate these communities. In Chapter four, rainbow trout were fed a commercial diet supplemented with P. acidilactici for four weeks. P. acidilactici was detected in the GIT of the probiotic group by multiple methods and P. acidilactici was able to persist for at least 24h at the cessation of probiotic feeding. Histological appraisal on the intestine revealed significantly higher microvilli density in the posterior mucosa and a higher density of goblet cells in the anterior mucosa of the probiotic fed fish. RT-PCR results demonstrated that IL-1β, IL-8 and IgT gene expression were up-regulated in the P. acidilactici fed fish at the end of the study. Whilst mRNA of PCNA, HSP70 and casp-3 were down-regulated in the probiotic group at both sampling points. In Chapter five, the efficacy of dietary administration of P. acidilactici and short chain fructooligosaccharide (scFOS) on Atlantic salmon (Salmo salar L.) was evaluated at 63 and 132 days. Compared to the control group, total bacterial cell counts in all regions of the intestine with exception of the anterior digesta were significantly lower in the synbiotic group at the mid sampling point. PCR-DGGE revealed that species richness, diversity and the number of OTUs were significantly higher in the synbiotic group in the anterior digesta at the mid sampling point. Intestinal microvilli and villi length were increased in the anterior intestine of the synbiotic fed group at the end sampling point. IEL levels were increased in the synbiotic group in the posterior intestine at both sampling points. The expression of immunological genes were significantly up-regulated in the synbiotic fed salmon. In Chapter six, rainbow trout were fed three diets fishmeal (FM), soybean meal (SBM) and PlantMix diets supplemented with or without P. acidilactici for 12 weeks. At both sampling points, with exception of fish fed FM, LAB levels were significantly higher in all probiotic groups compared to the control groups. Serum lysozyme activity was significantly higher in fish fed FM and SBM diets containing P. acidilactici than that of fish fed the control diets. This body of research demonstrates that P. acidilactici can modulate immune response via up-regulation of immune genes as well as modulate IEL and goblet cell levels. Despite these benefits, P. acidilactici had no detrimental effects on growth performance.Ministry of Higher Education and Scientific research in Ira

    Differences in Sockeye Salmon Antibody Composition: Testing The Immunological Imprinting Hypothesis

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    Anadromous fish such as sockeye salmon return to their natal streams to spawn, during which they undergo significant physiological changes including the release of cortisol, a known immunosuppressive hormone. Our lab has proposed the Immunological Imprinting Hypothesis, which suggests that juvenile anadromous fish respond to pathogens specific to their natal site by producing protective long lived plasma cells (LLPCs) that constitutively produce antibodies against those pathogens. These LLPCs are believed to be highly cortisol resistant. Thus, fish returning to their natal streams have immunological protection from pathogens found at that specific location. I investigated the Immunological Imprinting Hypothesis through analysis of antibody composition and usage. Since 2009 samples of Sockeye Salmon spleen and anterior kidney have been harvested from two separate salmon runs in Alaska. Using quantitative PCR (qPCR) I examined the relative usage levels of specific VH gene families between fish at different locations. to further investigate the “pathogen fingerprint” of given spawning sites, I also performed qPCR analysis in order to compare the pathogen loads of multiple pathogens from different sites, including Bacterial Kidney Disease (Renibacterium salmoninarum), Bacterial Coldwater Disease (Flavobacterium psychrophilum), and Infectious Hematopoietic Necrosis Virus (IHNV). Analysis of VH family usage suggests that differences exist between certain spawning locations not only for selected individual VH families, but also for multiple VH families analyzed simultaneously. Likewise, pathogen loads and infection rates are found to differ frequently between many spawning sites, while probability of infection is shown to be dependent on location for each pathogen analyzed. Analysis of VH usage and pathogen loads suggests several correlations that exist between specific usage patterns and lower pathogenic loads. Greater understanding of spawning fish immune functioning can potentially suggest a method of natural immunization against common fish pathogens and thus protect both farmed and wild populations. These differences in VH usage patterns and pathogen infection rates between spawning sites provide strong evidence in support of the Immunological Imprinting Hypothesis

    A first generation BAC-based physical map of the rainbow trout genome

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    Background: Rainbow trout (Oncorhynchus mykiss) are the most-widely cultivated cold freshwater fish in the world and an important model species for many research areas. Coupling great interest in this species as a research model with the need for genetic improvement of aquaculture production efficiency traits justifies the continued development of genomics research resources. Many quantitative trait loci (QTL) have been identified for production and life-history traits in rainbow trout. A bacterial artificial chromosome (BAC) physical map is needed to facilitate fine mapping of QTL and the selection of positional candidate genes for incorporation in marker-assisted selection (MAS) for improving rainbow trout aquaculture production. This resource will also facilitate efforts to obtain and assemble a whole-genome reference sequence for this species.[br/] Results: The physical map was constructed from DNA fingerprinting of 192,096 BAC clones using the 4-color high-information content fingerprinting (HICF) method. The clones were assembled into physical map contigs using the finger-printing contig (FPC) program. The map is composed of 4,173 contigs and 9,379 singletons. The total number of unique fingerprinting fragments (consensus bands) in contigs is 1,185,157, which corresponds to an estimated physical length of 2.0 Gb. The map assembly was validated by 1) comparison with probe hybridization results and agarose gel fingerprinting contigs; and 2) anchoring large contigs to the microsatellite-based genetic linkage map.[br/] Conclusion: The production and validation of the first BAC physical map of the rainbow trout genome is described in this paper. We are currently integrating this map with the NCCCWA genetic map using more than 200 microsatellites isolated from BAC end sequences and by identifying BACs that harbor more than 300 previously mapped markers. The availability of an integrated physical and genetic map will enable detailed comparative genome analyses, fine mapping of QTL, positional cloning, selection of positional candidate genes for economically important traits and the incorporation of MAS into rainbow trout breeding programs

    The Role of Multi-factor Authentication for Modern Day Security

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    Multi-factor Authentication (MFA) often referred to as Two-factor Authentication (2FA), which is a subset of MFA, is the practice of implementing additional security methods on top of a standard username and password to help authenticate the identity of a user and increase the security of data.This chapter will investigate the problem with username and password logins, the different types of authentication, current best practice for multi-factor authentication and interpretations about how the technology will grow in the upcoming years

    Cryptanalysis the SHA-256 Hash Function using Rainbow Tables

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    The research of the strength of a hashed message is of great importance in modern authentication systems. The hashing process is inextricably linked with the password system, since passwords are usually stored in the system not in clear text, but as hashes. The SHA-256 hash function was chosen to model the attack with rainbow tables. An algorithm for constructing a rainbow table for the SHA-256 hash function in the Java language is proposed. The conditions under which the use of rainbow tables will be effective are determined. This article aims to practically show the process of generating a password and rainbow tables to organize an attack on the SHA-256 hash function. As research shows, rainbow tables can reveal a three-character password in 3 seconds. As the password bit increases, the decryption time increases in direct proportion

    A profile of prolonged, persistent SSH attack on a Kippo Based Honeynet

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    This paper is an investigation focusing on activities detected by SSH honeypots that utilised kippo honeypot software. The honeypots were located across a variety of geographical locations and operational platforms. The honeynet has suffered prolonged, persistent and attack from a /24 network which appears to be of Chinese geographical origin. In addition to these attacks, other attackers have been successful in compromising real hosts in a wide range of other countries that were subsequently involved in attacking the honeypot machines in the honeynet

    Big Explosions and Strong Gravity

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    This guide has been developed to assist people who would like to run the Big Explosions and Strong Gravity event with their local Girl Scout Council. The event is a one-day event in which a group of Girl Scouts spends their time doing a series of hands-on activities on spectroscopy, cosmic abundances, supernovae, and black holes. Professional scientists, engineers, and graduate students assist with these activities, giving the scouts a chance to interact with professionals in science and technology fields. Educational levels: Informal education

    Invited Paper - A Profile of Prolonged, Persistent SSH Attack on a Kippo Based Honeynet

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    This paper is an investigation focusing on activities detected by SSH honeypots that utilised kippo honeypot software. The honeypots were located across a variety of geographical locations and operational platforms. The honeynet has suffered prolonged, persistent and attack from a /24 network which appears to be of Chinese geographical origin. In addition to these attacks, other attackers have been successful in compromising real hosts in a wide range of other countries that were subsequently involved in attacking the honeypot machines in the honeynet. Keywords: Cyber Security, SSH, Secure Shell, Honeypots, Kipp

    THE MOLECULAR DIFFERENTIATION OF RENIBACTERIUM SALMONINARUM ISOLATES

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    Studies were undertaken to examine the extent of molecular variation among isolates of the fish pathogen Renibacterium salmoninarum. As many isolates as possible were gathered from diagnostic laboratories within the UK, and checked for viability and contamination. The isolates were derived mainly from infected rainbow trout and Atlantic salmon that were farmed in England, Scotland and Wales, subject to the requirements of statutory legislation. Incomplete histories were available for the sources of the isolates, which spanned a time scale of 36 years, from 1962-1998. Molecular variation between the isolates was examined using two strategies. Firstly, defined regions of the genome were examined for polymorphisms. PCR analysis of previously characterised genes, msa, hly, and rsh, revealed no length polymorphisms among 43 UK isolates of R. salmoninarum. The 23S and 5S rRNA genes were sequenced and sequence analysis of the 16S- 23S (ITS I) and 23S-SS (ITS2) rRNA regions was performed. Sequence analysis confirmed the correct taxonomic placement of R. salmoninarum within the Micrococcus/Arthrobacter subdivision of the Actinomycetes. Some isolates possessed small sequence variations within ITS1 that can provide an indication of their geographical origins. Sequence variation also exists in the ITS2 region but was found only within a single isolate from an outlying region of Canada. Ribotyping was found to be of limited use for discriminating among isolates of R. salmoninarum probably because R. salmoninarum possesses only two copies of the rRNA operon with no length polymorphisms in the ITS regions. Additionally, the discovery and analysis of a genetic locus containing a 51 bp exact tandem repeat unit (designated ETR-A), revealed that some isolates of R. salmoninarum could be distinguished by the possession of one rather than two copies of this repeat unit. Finally, PCR amplification of length polymorph isms in the tRNA gene spacer regions (tDNA-PCR) was developed using consensus tRNA gene primers to enable tRNA genes and spacer regions to be cloned and sequenced. Subsequently, specific tRNA gene primers were designed and enabled the discrimination of 43 UK isolates into I 5 groupings. tDNA-PCR proved to be one of the most powerful typing methods applied to this organism. Secondly, typing methods that analysed the whole genome for the presence of molecular variation were employed. A putative insertion sequence IS994, was used as a probe in a RFLP-based study to discriminate between 52 isolates of R. salmoninarum from different countries. This method showed great potential for distinguishing between isolates and separated the 52 isolates that were examined into 12 groupings. Randomly amplified polymorphic DNA (RAPD) was also used to examine 28 isolates of UK origin. This method was found to be highly discriminatory, with 28 isolates generating 12 different banding patterns, which appeared to reflect geographical source. Pulsed field gel electrophoresis was also used to investigate the genomic diversity of isolates. Due to technical difficulties in obtaining pure, undamaged DNA the preparation of suitable macro restriction profiles was never achieved. However, preliminary findings suggested that the R. salmoninarum chromosome was linear and approximately 4.5-6Mb in size. Finally, repetitive element PCR was evaluated using 3 different approaches (ERIC, REP and BOXA-2) but proved to have a limited capacity for defining molecular variation between different isolates. Ultimately, RAPD, tDNA-PCR and 1S994 RFLP profiling proved to be most useful for the molecular differentiation of R. salmoninarum. A comparison of the groupings that resulted from each of these methods revealed substantial areas of agreement. The use of a multifactorial approach not only resulted in a greater discrimination of isolates but also provided increased confidence in the outcome. It is recommended that for typing purposes such an approach should be adopted. Epizootiological interpretations of groupings were hampered by the general lack of background information attached to each isolate. However, the application of multiple typing methods reveal that, despite the highly conserved nature of this bacterium, UK isolates of R. salmoninarum possess genetic diversity, with geographically related isolates often being grouped together. Overall there was little evidence to suggest the regular introduction of genetically distinct R. salmoninarum into the UK and the results suggest that some isolates may be relatively localised despite the international trade in fish stocks.The Centre for Environment, Fisheries and Aquaculture Science, Weymouth, Dorse
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