3,152 research outputs found

    Polygraph: Automatically generating signatures for polymorphic worms

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    It is widely believed that content-signature-based intrusion detection systems (IDSes) are easily evaded by polymorphic worms, which vary their payload on every infection attempt. In this paper, we present Polygraph, a signature generation system that successfully produces signatures that match polymorphic worms. Polygraph generates signatures that consist of multiple disjoint content sub-strings. In doing so, Polygraph leverages our insight that for a real-world exploit to function properly, multiple invariant substrings must often be present in all variants of a payload; these substrings typically correspond to protocol framing, return addresses, and in some cases, poorly obfuscated code. We contribute a definition of the polymorphic signature generation problem; propose classes of signature suited for matching polymorphic worm payloads; and present algorithms for automatic generation of signatures in these classes. Our evaluation of these algorithms on a range of polymorphic worms demonstrates that Polygraph produces signatures for polymorphic worms that exhibit low false negatives and false positives. © 2005 IEEE

    Visitor perceptions of captive wildlife tourism in a Western Australian natural setting

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    Wildlife tourism involves a broad sweep of experiences that includes all of the aspects of the tourism genre with the distinguishing feature of animals as the primary attraction. The uniqueness of Australian wildlife in combination with factors such as remoteness and rarity appear to have provided the ideal context for successful wildlife tourism operations. Barna Mia, located in a large remnant woodland in the central southern wheatbelt of Western Australia, is approximately 165 km southeast of the state's capital, Perth. Dryandra Woodland, the location of Banra Mia consists of a closely grouped and connected cluster of native remnant vegetation blocks. The enclosure is surrounded by electrified, vermin proof fencing to keep feral predators out and the captive fauna in. The results of the visitor survey at Barna Mia suggested the experience provided a great sense of satisfaction amongst respondents. This was both in terms of the overall satisfaction as well as satisfaction with specific parts of the experience. The feeling of being 'in the wild' may have been enhanced by the lack of barriers between visitors and the animals and the absence of constraints on animal movement through the enclosure. Improving the operation of Barna Mia as an attraction in itself and as part of the Dryandra Woodland product may serve to improve its success as an attraction. However, an innately attractive tourism experience cannot work without appropriate integration within the specific wildlife tourism product of Dryandra Woodland, while coordination with tourism on a regional scale is also important

    Computation of leading-edge vortex flows

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    The simulation of the leading edge vortex flow about a series of conical delta wings through solution of the Navier-Stokes and Euler equations is studied. The occurrence, the validity, and the usefulness of separated flow solutions to the Euler equations of particular interest. Central and upwind difference solutions to the governing equations are compared for a series of cross sectional shapes, including both rounded and sharp tip geometries. For the rounded leading edge and the flight condition considered, viscous solutions obtained with either central or upwind difference methods predict the classic structure of vortical flow over a highly swept delta wing. Predicted features include the primary vortex due to leading edge separation and the secondary vortex due to crossflow separation. Central difference solutions to the Euler equations show a marked sensitivity to grid refinement. On a coarse grid, the flow separates due to numerical error and a primary vortex which resembles that of the viscous solution is predicted. In contrast, the upwind difference solutions to the Euler equations predict attached flow even for first-order solutions on coarse grids. On a sufficiently fine grid, both methods agree closely and correctly predict a shock-curvature-induced inviscid separation near the leeward plane of symmetry. Upwind difference solutions to the Navier-Stokes and Euler equations are presented for two sharp leading edge geometries. The viscous solutions are quite similar to the rounded leading edge results with vortices of similar shape and size. The upwind Euler solutions predict attached flow with no separation for both geometries. However, with sufficient grid refinement near the tip or through the use of more accurate spatial differencing, leading edge separation results. Once the leading edge separation is established, the upwind solution agrees with recently published central difference solutions to the Euler equations

    Environmental determinants for repeatability of activity patterns in free-ranging elasmobranchs

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    Repeatability of behaviour is the degree of behavioural variation attributed to differences between- or within- individuals in a population and may often be conceptualised as animal personality. Behaviour is often plastic in response to environmental challenges to maximise individual survival. In ectotherms, this may be expressed as changes in behaviours due to higher environmental temperatures increasing metabolic demand. Personality is thought to constrain this behavioural plasticity as individuals express behaviours within their personality type. Most studies in this field have been conducted under controlled or semi-controlled conditions, which control for confounding factors and hence remain limited in their applicability in the face of uncertain field conditions. To date, no field studies have focused on the environmental conditions that determine how repeatability of behaviour is exhibited. Here we use biotelemetry tag derived activity data to assess environmental factors influencing the repeatability of activity patterns (i.e., repeated behaviours) in two euryhaline free-ranging elasmobranchs with differing life histories; the largetooth sawfish (Pristis pristis) and bull shark (Carcharhinus leucas) in the Fitzroy River. In response to increasing environmental temperatures and metabolism across the study period, between-individual repeatability of behaviour varied in sawfish, but not bull sharks. Overall between-individual repeatability of behaviour increased across the study period as sawfish altered their behaviours presumably to mitigate competition. Between-individual repeatability of behaviour decreased across the study period with respect to diurnal activity rhythms, indicating sawfish became less diurnal in their activity use. This may indicate active avoidance of the hottest part of the day and a loss to individuals’ ability to temporally partition the diel cycle, with more overlap in activity apparent in the population. Additionally, individuals showed consistent individual differences in their within-individual repeatability of behaviour. This further supports the hypothesis that individuals of these species exhibit personalities. Ecological pressures such as competition, predation pressure and resource constraints are potential drivers of the formation of personality, both in this system and in general. This study demonstrates that repeatability of behaviour can be studied in the field using acoustic telemetry. Additionally, this approach can be used to understand the effects of environmental change on specialisation in other aquatic ectotherms

    Addressing Public Health Risks of Persistent Pollutants Through Nutritional Modulation and Biomimetic Nanocomposite Remediation Platforms

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    Due to their relative chemical stability and ubiquity in the environment, chlorinated organic contaminants such as polychlorinated biphenyls (PCBs) pose significant health risks and enduring remediation challenges. Engineered nanoparticles (NPs) provide a novel platform for sensing/remediation of these toxicants, in addition to the growing use of NPs in many industrial and biomedical applications, but there remains concern for their potential long-term health effects. Research highlighted herein also represents a transdisciplinary approach to address human health challenges associated with exposure to PCBs and NPs. The objectives of this dissertation research are two-fold, 1) to develop effective methods for capture/sensing and remediation of environmental toxicants, and 2) to better understand associated risks and to elucidate relevant protective mechanisms, such as lifestyle-related modulators of environmental disease. Prevalent engineered nanoparticles, including aluminum oxide and titanium dioxide, have been studied to better understand effective nanoparticle dispersion methods for in vitro nanotoxicology studies. This work has served both to effectively stabilize these nanoparticles under physiological conditions and to better understand the associated mechanisms of toxicity, which links these metal nanoparticles to endothelial oxidative stress and inflammation through phosphorylation of key cellular signaling molecules and increased DNA binding of pro-inflammatory NFκB. Surface functionalization, though, is being found to limit potential toxicity and has been utilized in subsequent research. A novel polyphenol-functionalized, NP-based system has been developed which combines the biomimetic binding capabilities of nutrient polyphenols with the separation and heating capabilities of superparamagnetic iron oxide NPs for the capture/sensing of organic contaminants in polluted water sources. Magnetic nanocomposite microparticles (MNMs) incorporating the fluorescent polyphenols quercetin and curcumin exhibit high affinity for model organic pollutants followed by rapid magnetic separation, addressing the need for sustainable pollutant remediation. Further work has been performed to both better understand health concerns associated with environmental toxicants such as PCBs and to determine effective methods for modulating their toxicity. This research has shown that PCB remediation through dechlorination is a viable technique for decreasing endothelial inflammation, although complete dechlorination to biphenyl is necessary to effectively eliminate superoxide production, NFκB activation, and induction of inflammatory markers. Additionally, the nutrient polyphenol EGCG, found in green tea, has been shown to serve as a biomedical modulator of in vivo PCB toxicity by up-regulating a battery of antioxidant enzymes transcriptionally controlled by AhR and Nrf2 proteins

    The Solubility of Certain Substituted Benzoic Acids in Typical Salt Solutions at 25°

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    The solubility of the ortho-, meta- and para aminobenzoic acids, of the ortho-, meta- and para hydroxybenzoic acids, and of ortho- and meta nitrobenzoic acids in typical salts solutions at 25° has been determined. The salts were sodium chloride, barium chloride, potassium sulphate and magnesium sulphate

    Mediating Disputes Arising Out of Troubled Companies - Do It Sooner Rather than Later

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    Over the last several years, there has been much academic debate on the subject of “vanishing trials”—whether the settlement rate in bankruptcy and other courts is accelerating, and whether that is a healthy trend for our justice system. A more interesting question is why disputes in chapter 11 cases are not resolved sooner. Why does it take so much time and so much money for parties to settle their differences and arrive at a consensual chapter 11 plan? Cite as 42 Golden Gate U. L. Rev. 661 (2012)

    The Thermal Decomposition of Hexane at High Pressures

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    The thermal decomposition of n-hexane has been studied at pressures between 14,000 and 15,000 lbs., at temperatures between 430° and 520°\u27 and for heating periods varying from a few minutes to two hours

    Mediating Disputes Arising Out of Troubled Companies - Do It Sooner Rather than Later

    Get PDF
    Over the last several years, there has been much academic debate on the subject of “vanishing trials”—whether the settlement rate in bankruptcy and other courts is accelerating, and whether that is a healthy trend for our justice system. A more interesting question is why disputes in chapter 11 cases are not resolved sooner. Why does it take so much time and so much money for parties to settle their differences and arrive at a consensual chapter 11 plan? Cite as 42 Golden Gate U. L. Rev. 661 (2012)

    Evaluation of geotourism potential through geographic information systems

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    Geotourism aims to provide opportunities for visitors to view and experience geological and geomorphological processes in a way that generates appreciation and understanding of the environment
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