Modelling client puzzles and denial-of-service resistant protocols

Denial-of-service (DoS) attacks are a growing concern to networked services like the Internet. In recent years, major Internet e-commerce and government sites have been disabled due to various DoS attacks. A common form of DoS attack is a resource depletion attack, in which an attacker tries to overload the server's resources, such as memory or computational power, rendering the server unable to service honest clients. A promising way to deal with this problem is for a defending server to identify and segregate malicious traffic as earlier as possible. Client puzzles, also known as proofs of work, have been shown to be a promising tool to thwart DoS attacks in network protocols, particularly in authentication protocols. In this thesis, we design efficient client puzzles and propose a stronger security model to analyse client puzzles. We revisit a few key establishment protocols to analyse their DoS resilient properties and strengthen them using existing and novel techniques. Our contributions in the thesis are manifold. We propose an efficient client puzzle that enjoys its security in the standard model under new computational assumptions. Assuming the presence of powerful DoS attackers, we find a weakness in the most recent security model proposed to analyse client puzzles and this study leads us to introduce a better security model for analysing client puzzles. We demonstrate the utility of our new security definitions by including two hash based stronger client puzzles. We also show that using stronger client puzzles any protocol can be converted into a provably secure DoS resilient key exchange protocol. In other contributions, we analyse DoS resilient properties of network protocols such as Just Fast Keying (JFK) and Transport Layer Security (TLS). In the JFK protocol, we identify a new DoS attack by applying Meadows' cost based framework to analyse DoS resilient properties. We also prove that the original security claim of JFK does not hold. Then we combine an existing technique to reduce the server cost and prove that the new variant of JFK achieves perfect forward secrecy (the property not achieved by original JFK protocol) and secure under the original security assumptions of JFK. Finally, we introduce a novel cost shifting technique which reduces the computation cost of the server significantly and employ the technique in the most important network protocol, TLS, to analyse the security of the resultant protocol. We also observe that the cost shifting technique can be incorporated in any Diffine{Hellman based key exchange protocol to reduce the Diffie{Hellman exponential cost of a party by one multiplication and one addition.

Fire safety of buildings based on realistic fire time-temperature curves

In recent times, fire has become a major disaster in buildings due to the increase in fire loads, as a result of modern furniture and light weight construction. This has caused problems for safe evacuation and rescue activities, and in some instances lead to the collapse of buildings (Lewis, 2008 and Nyman, 2002). Recent research has shown that the actual fire resistance of building elements exposed to building fires can be less than their specified fire resistance rating (Lennon and Moore, 2003, Jones, 2002, Nyman, 2002 and Abecassis-Empis et al. 2008). Conventionally the fire rating of building elements is determined using fire tests based on the standard fire time-temperature curve given in ISO 834. This ISO 834 curve was developed in the early 1900s, where wood was the basic fuel source. In reality, modern buildings make use of thermoplastic materials, synthetic foams and fabrics. These materials are high in calorific values and increase both the speed of fire growth and heat release rate, thus increasing the fire severity beyond that of the standard fire curve. Hence it suggests the need to use realistic fire time-temperature curves in tests. Real building fire temperature profiles depend on the fuel load representing the combustible building contents, ventilation openings and thermal properties of wall lining materials. Fuel load is selected based on a review and suitable realistic fire time-temperature curves were developed. Fire tests were then performed for plasterboard lined light gauge steel framed walls for the developed realistic fire curves. This paper presents the details of the development of suitable realistic building fire curves, and the fire tests using them. It describes the fire performance of tested walls in comparison to the standard fire tests and highlights the differences between them. This research has shown the need to use realistic fire exposures in assessing the fire resistance rating of building elements.

Bond strength of steel hollow sections using carbon fibre reinforced polymer composites

This research was a step forward in developing bond strength of CFRP strengthened steel hollow sections under tension loads. The studies have revealed the ultimate load carrying capacity of the CFRP strengthened steel hollow sections and the stress distribution for different orientations of the CFRP sheet at different layers. This thesis presents a series of experimental and finite element analysis to determine a good understanding of the bond characteristics of CFRP strengthened steel hollow sections.

Predicting posttraumatic growth and posttraumatic stress in fire-fighters

Emergency service workers (e.g., fire-fighters, police and paramedics) are exposed to elevated levels of potentially traumatising events through the course of their work. Such exposure can have lasting negative consequences (e. g., Post Traumatic Stress Disorder; PTSD) and/or positive outcomes (e. g., Posttraumatic Growth; PTG). Research had implicated trauma, occupational and personal variables that account for variance in post-trauma outcomes yet at this stage no research has investigated these factors and their relative influence on both PTSD and PTG in a single study. Based in Calhoun and Tedeschi’s (2013) model of PTG and previous research, in this study regression models of PTG and PTSD symptoms among 218 fire-fighters were tested. Results indicated organisational factors predicted symptoms of PTSD, while there was partial support for the hypothesis that coping and social support would be predictors of PTG. Experiencing multiple sources of trauma, higher levels of organisational and operational stress, and utilising cognitive reappraisal coping, were all significant predictors of PTSD symptoms. Increases in PTG were predicted by experiencing trauma from multiple sources and the use of self-care coping. Results highlight the importance of organisational factors in the development of PTSD symptoms, and of individual factors for promoting PTG.

Composites for delivery of therapeutics : combining melt electrospun scaffolds with loaded electrosprayed microparticles

A novel strategy is reported to produce biodegradable microfiber-scaffolds layered with high densities of microparticles encapsulating a model protein. Direct electrospraying on highly porous melt electrospun scaffolds provides a reproducible scaffold coating throughout the entire architecture. The burst release of protein is significantly reduced due to the immobilization of microparticles on the surface of the scaffold and release mechanisms are dependent on protein-polymer interactions. The composite scaffolds have a positive biological effect in contact with precursor osteoblast cells up to 18 days in culture. The scaffold design achieved with the techniques presented here endorses these new composite scaffolds as promising templates for growth factor delivery.

Phenotypic changes in artemisinin-resistant plasmodium falciparum lines in vitro: evidence for decreased sensitivity to dormancy and growth inhibition

The appearance of Plasmodium falciparum parasites with decreased in vivo sensitivity but no measurable in vitro resistance to artemisinin has raised the urgent need to characterize the artemisinin resistance phenotype. Changes in the temporary growth arrest (dormancy) profile of parasites may be one aspect of this phenotype. In this study, we investigated the link between dormancy and resistance, using artelinic acid (AL)-resistant parasites. Our results demonstrate that the AL resistance phenotype has (i) decreased sensitivity of mature-stage parasites, (ii) decreased sensitivity of the ring stage to the induction of dormancy, and (iii) a faster recovery from dormancy.

Fabrication and electrocatalytic properties of polyaniline/Pt nanoparticle composites

Polyaniline (PANI)/Pt nanoparticle composites can be prepared by the spontaneous redox reaction of K2PtCl4 with PANI, to yield thin films that show electrocatalytic properties in both acidic and neutral aqueous media.

Wind-resistant low-rise buildings in the tropics

High-wind events such as storms and hurricanes cause severe damage to low-rise building (housing, schools, and industrial, commercial, and farm buildings). Roof claddings often suffer the worst, which then leads to accelerated damage to the whole building. Australia leads the way in solving this international problem through extensive research and development work, and has adequate documents in place. This paper first illustrates briefly the nature of high-wind events and then the commonly observed damage to buildings. Australian research work and design practice are then described, based on which suitable design recommendations for wind-resistant buildings are presented.

Sulfur resistant emissions catalyst

A catalyst comprising one or more complex oxides having a nominal compn. as set out in formula (1): AxB1-y-zMyPzOn (1) wherein A is selected from one or more group III elements including the lanthanide elements or one or more divalent or monovalent cations; B is selected from one or more elements with at. no. 22 to 24, 40 to 42 and 72 to 75; M is selected from one or more elements with at. no. 25 to 30; P is selected from one or more elements with at. no. 44 to 50 and 76 to 83; x is defined as a no. where 0

Comparative study of failure mechanisms in steel and concrete members strengthened with CFRP composites

Over the last decade advanced composite materials, like carbon fibre reinforced polymer (CFRP), have increasingly been used in civil engineering infrastructure. The benefits of advanced composites are rapidly becoming evident. This paper focuses on the comparative performance of steel and concrete members retrofitted by carbon fibre reinforced polymers. The objective of this work is a systematic assessment and evaluation of the performance of CFRP for both the concrete and steel members available in the technical literature. Existing empirical and analytical models were studied. Comparison is made with respect to failure mode, bond characteristics, fatigue behaviour, durability, corrosion, load carrying capacity and force transfer. It is concluded that empirical expressions for the concrete-CFRP composite are not readily suited for direct use in the steel-CFRP composite. This paper identifies some of the major issues that need further investigation.

Management of endocrine resistant breast cancer

Metastatic breast cancer (MBC) may present de novo but more commonly develops in women initially presenting with early breast cancer despite the widespread use of adjuvant hormonal and cytotoxic chemotherapy. MBC is incurable. Hormone sensitive MBC eventually becomes resistant to endocrine therapy in most women. Anthracyclines are the agents of choice in the treatment of endocrine resistant MBC. With the widespread use of anthracyclines in the adjuvant setting, taxanes have become the agents of choice for many patients. Recently capecitabine has become established as a standard of care for patients pretreated with anthracyclines and taxanes. However, a range of agents have activity as third line treatment. These include gemcitabine, vinorelbine and platinum analogues. The sequential use of non-cross resistant single agents rather than combination therapy is preferable in most women with MBC. Even though combination therapy can improve response rates and increase progression free interval, there is no robust evidence to indicate an advantage in terms of overall survival. Moreover, combination therapy is associated with a higher toxicity rate and poor quality of life. There is no role for dose-intense therapy, high dose therapy or maintenance chemotherapy outside the context of a clinical trial. The introduction of trastuzumab, monoclonal antibody targeting growth factor receptors, has improved the therapeutic options for women with tumours overexpressing HER2/neu. DNA micro-array profiles of tumours can potentially help to individualise therapy in future. Molecular targeted therapy has the potential to revolutionise the management of MBC.

Expression patterns of vascular-specific promoters RolC and Sh in transgenic potatoes and their use in engineering PLRV-resistant plants

The expression patterns of GUS fusion constructs driven by the Agrobacterium rhizogenes RolC and the maize Sh (Shrunken: sucrose synthase-1) promoters were examined in transgenic potatoes (cv. Atlantic). RolC drove high-level gene expression in phloem tissue, bundle sheath cells and vascular parenchyma, but not in xylem or non-vascular tissues. Sh expression was exclusively confined to phloem tissue. Potato leafroll luteovirus (PLRV) replicates only in phloem tissues, and we show that when RolC is used to drive expression of the PLRV coat protein gene, virus-resistant lines can be obtained. In contrast, no significant resistance was observed when the Sh promoter was used.

Influence of kaolinite/carbon black hybridization on combustion and thermal decomposition behaviors of NR composites

A series of NR composites filled with modified kaolinite (MK), carbon black (CB) and the hybrid fillercontained MK and CB, were prepared by melt blending. The microstructure, combustion and thermaldecomposition behaviors of NR composites were characterized by TEM, XRD, infrared spectroscopy, conecalorimeter test (CCT) and thermal-gravimetric analysis (TG). The results show that the filler hybridizationcan improve the dispensability and shape of the kaolinite sheets in the rubber matrix and change theinterface bond between kaolinite particles and rubber molecules. NR-3 filled by 10 phr MK and 40 phr CBhas the lowest heat release rate (HRR), mass loss rate (MLR), total heat release (THR), smoke productionrate (SPR) and the highest char residue among all the NR composites. Therefore, the hybridization ofthe carbon black particles with the kaolinite particles can effectively improve the thermal stability andcombustion properties of NR composites.

Targeting amino acid transport in metastatic castration-resistant prostate cancer : effects on cell cycle, cell growth, and tumor development

Background L-type amino acid transporters (LATs) uptake neutral amino acids including L-leucine into cells, stimulating mammalian target of rapamycin complex 1 signaling and protein synthesis. LAT1 and LAT3 are overexpressed at different stages of prostate cancer, and they are responsible for increasing nutrients and stimulating cell growth. Methods We examined LAT3 protein expression in human prostate cancer tissue microarrays. LAT function was inhibited using a leucine analog (BCH) in androgen-dependent and -independent environments, with gene expression analyzed by microarray. A PC-3 xenograft mouse model was used to study the effects of inhibiting LAT1 and LAT3 expression. Results were analyzed with the Mann-Whitney U or Fisher exact tests. All statistical tests were two-sided. Results LAT3 protein was expressed at all stages of prostate cancer, with a statistically significant decrease in expression after 4–7 months of neoadjuvant hormone therapy (4–7 month mean = 1.571; 95% confidence interval = 1.155 to 1.987 vs 0 month = 2.098; 95% confidence interval = 1.962 to 2.235; P = .0187). Inhibition of LAT function led to activating transcription factor 4–mediated upregulation of amino acid transporters including ASCT1, ASCT2, and 4F2hc, all of which were also regulated via the androgen receptor. LAT inhibition suppressed M-phase cell cycle genes regulated by E2F family transcription factors including critical castration-resistant prostate cancer regulatory genes UBE2C, CDC20, and CDK1. In silico analysis of BCH-downregulated genes showed that 90.9% are statistically significantly upregulated in metastatic castration-resistant prostate cancer. Finally, LAT1 or LAT3 knockdown in xenografts inhibited tumor growth, cell cycle progression, and spontaneous metastasis in vivo. Conclusion Inhibition of LAT transporters may provide a novel therapeutic target in metastatic castration-resistant prostate cancer, via suppression of mammalian target of rapamycin complex 1 activity and M-phase cell cycle genes.

Investigating well-being and mental health in Queensland fire-fighters

This thesis used survey and interview methods to examine how organisational and interpersonal factors impact on the mental health of fire and rescue workers. It was the first published research to assess and predict multiple indicators of mental health; psychological distress, well-being, posttraumatic growth and posttraumatic stress disorder symptoms. The results provide valuable information for supporting fire and rescue workers through psychoeducation and proactive intervention programs.