1,499 research outputs found

    Performance evaluation of DCA and SRC on a single bot detection

    Get PDF
    Malicious users try to compromise systems using new techniques. One of the recent techniques used by the attacker is to perform complex distributed attacks such as denial of service and to obtain sensitive data such as password information. These compromised machines are said to be infected with malicious software termed a “bot”. In this paper, we investigate the correlation of behavioural attributes such as keylogging and packet flooding behaviour to detect the existence of a single bot on a compromised machine by applying (1) Spearman’s rank correlation (SRC) algorithm and (2) the Dendritic Cell Algorithm (DCA). We also compare the output results generated from these two methods to the detection of a single bot. The results show that the DCA has a better performance in detecting malicious activities

    The dendritic cell algorithm for intrusion detection

    Get PDF

    The dendritic cell algorithm for intrusion detection

    Get PDF
    As one of the solutions to intrusion detection problems, Artificial Immune Systems (AIS) have shown their advantages. Unlike genetic algorithms, there is no one archetypal AIS, instead there are four major paradigms. Among them, the Dendritic Cell Algorithm (DCA) has produced promising results in various applications. The aim of this chapter is to demonstrate the potential for the DCA as a suitable candidate for intrusion detection problems. We review some of the commonly used AIS paradigms for intrusion detection problems and demonstrate the advantages of one particular algorithm, the DCA. In order to clearly describe the algorithm, the background to its development and a formal definition are given. In addition, improvements to the original DCA are presented and their implications are discussed, including previous work done on an online analysis component with segmentation and ongoing work on automated data preprocessing. Based on preliminary results, both improvements appear to be promising for online anomaly-based intrusion detection.Comment: Bio-Inspired Communications and Networking, IGI Global, 84-102, 201

    Serotonin, how to find it...

    Get PDF
    Serotonin or 5-hydroxytryptamine (5-HT) is a monoamine neurotransmitter. Biochemically derived from tryptophan, serotonin is primarily found in the gastrointestinal tract, platelets, and in the central nervous system (CNS) of animals, including humans. Discovered and crystallized over sixty years ago, serotonin operates as a short-range neurotransmitter as well as a long-range signalling modulator, with multiple effects on whole organism functions via plasma, platelet and neuroendocrine, gut, adrenal and other peripheral systems across many species. All of the important functions of serotonin in the brain and body were identified over the ensuing years by neurochemical, physiological and pharmacological investigations. Mainly, all these investigations have been performed via invasive methodologies, particularly in the CNS studies. Here we present a rapid overview of such methodological approaches focussing on voltammetry, one of the most recent technical approaches for serotonin analysis in vivo, in situ and in real time. Furthermore, we introduce a late technical evolution in the attempt to obtain in vivo non invasive measurement of brain serotonin.peer-reviewe

    Using Lidar Data to Analyse Sinkhole Characteristics Relevant for Understory Vegetation under Forest Cover\u2014Case Study of a High Karst Area in the Dinaric Mountains

    Get PDF
    In this article, we investigate the potential for detection and characterization of sinkholes under dense forest cover by using airborne laser scanning data. Laser pulse returns from the ground provide important data for the estimation of digital elevation model (DEM), which can be used for further processing. The main objectives of this study were to map and determine the geomorphometric characteristics of a large number of sinkholes and to investigate the correlations between geomorphology and vegetation in areas with such characteristics. The selected study area has very low anthropogenic influences and is particularly suitable for studying undisturbed karst sinkholes. The information extracted from this study regarding the shapes and depths of sinkholes show significant directionality for both orientation of sinkholes and their distribution over the area. Furthermore, significant differences in vegetation diversity and composition occur inside and outside the sinkholes, which indicates their presence has important ecological impacts

    ANAEROBIC BIODEGRADATION OF ETHYLENE DIBROMIDE AND 1,2-DICHLOROETHANE IN THE PRESENCE OF FUEL HYDROCARBONS

    Get PDF
    Field evidence from underground storage tank (UST) sites where leaded gasoline leaked indicates the lead scavengers 1,2-dibromoethane (ethylene dibromide, or EDB) and 1,2-dichloroethane (1,2-DCA) may be present in groundwater at levels that pose unacceptable risk. These compounds are seldom tested for at UST sites. Although dehalogenation of EDB and 1,2-DCA is known to occur, the effect of fuel hydrocarbons on their biodegradability under anaerobic conditions is poorly understood. Microcosms (2 L glass bottles) were prepared with soil and groundwater from a UST site in Clemson, South Carolina, using samples collected from the source (containing residual fuel) and less contaminated downgradient areas. Anaerobic biodegradation of EDB occurred in microcosms simulating natural attenuation, but was more extensive and predictable in treatments biostimulated with lactate. In the downgradient biostimulated microcosms, EDB decreased below its maximum contaminant level (MCL) (0.05 µg/L) at a first order rate of 9.4 ± 0.2 yr-1. The pathway for EDB dehalogenation proceeded mainly by dihaloelimination to ethene in the source microcosms, while sequential hydrogenolysis to bromoethane and ethane was predominant in the downgradient treatments. Biodegradation of EDB in the source microcosms was confirmed by carbon specific isotope analysis, with a 13C enrichment factor of -5.6. The highest levels of EDB removal occurred in microcosms that produced the highest amounts of methane. Extensive biodegradation of benzene, ethylbenzene, toluene and ortho-xylene was also observed in the source and downgradient area microcosms. In contrast, biodegradation of 1,2-DCA proceeded at a considerably slower rate than EDB, with no response to lactate additions. The slower biodegradation rates for 1,2-DCA agree with field observations and indicate that even if EDB is removed to below its MCL, 1,2-DCA may persist. Separate experiments were carried out to assess the potential inhibitory interactions between 1,2-DCA and EDB, which might explain the observed persistence of these compounds where leaded gasoline was released. Preliminary experiments were conducted to determine if an enrichment culture that chlororespires PCE and TCE developed at Clemson University was also capable of respiring EDB and 1,2-DCA. The culture was found to have the ability to rapidly dehalorespire EDB and 1,2-DCA, currently the only mixed culture known to do so. However, when the culture was fed both compounds simultaneously, it degraded EDB at the expense of 1,2-DCA in all cases. When the culture was enriched on EDB, activity on 1,2-DCA was completely inhibited, even after EDB was gone. No amount of 1,2-DCA inhibited the rate of EDB degradation down to part-per-trillion levels. Any previous exposure to EDB precluded the culture\u27s ability to consume 1,2-DCA. Remarkably, when the culture was enriched on 1,2-DCA and subsequently exposed to both EDB and 1,2-DCA, EDB was consumed first. EDB clearly inhibited 1,2-DCA biodegradation, and the degree of 1,2-DCA inhibition was roughly proportional to the concentration of EDB. This clear pattern of 1,2-DCA inhibition by EDB may contribute to its observed persistence in laboratory and field studies and merits further evaluation. Currently, decision makers have little information to guide remedial choices at UST sites contaminated with leaded gasoline additives. An analytical model was used to simulate the effects of partial source removal and plume remediation on EDB and 1,2-DCA plumes at contaminated UST sites. The risk posed by EDB, 1,2-DCA, and comingled gasoline hydrocarbons varies throughout the plume over time. Dissolution from the light nonaqueous phase liquid (LNAPL) determines the concentration of each contaminant near the source, but biological decay in the plume has a greater influence as distance downgradient from the source increases. For this reason, compounds that exceed regulatory standards near the source may not in downgradient plume zones. At UST sites, partial removal of a residual LNAPL source mass may serve as a stand alone remedial technique if dissolved concentrations in the source zone are within a couple orders of magnitude of the applicable government or remedial standards. This may be the case with 1,2-DCA; however EDB is likely to be found at concentrations that are orders of magnitude higher than its low MCL of 0.05 µg/L. For sites with significant EDB contamination, even when plume remediation is combined with source depletion, significant timeframes may be required to mitigate the impact of this compound. Benzene and MTBE are commonly the focus of remedial efforts at UST sites, but simulations presented here suggest that EDB, and to a lesser extent 1,2-DCA could be the critical contaminants to consider in the remediation design process at many sites
    • …
    corecore