Enhanced three-factor security protocol for consumer USB mass storage devices

The Universal Serial Bus (USB) is an extremely popular interface standard for computer peripheral connections and is widely used in consumer Mass Storage Devices (MSDs). While current consumer USB MSDs provide relatively high transmission speed and are convenient to carry, the use of USB MSDs has been prohibited in many commercial and everyday environments primarily due to security concerns. Security protocols have been previously proposed and a recent approach for the USB MSDs is to utilize multi-factor authentication. This paper proposes significant enhancements to the three-factor control protocol that now makes it secure under many types of attacks including the password guessing attack, the denial-of-service attack, and the replay attack. The proposed solution is presented with a rigorous security analysis and practical computational cost analysis to demonstrate the usefulness of this new security protocol for consumer USB MSDs.

Robust multimodal face and fingerprint fusion in the presence of spoofing attacks

Anti-spoofing is attracting growing interest in biometrics, considering the variety of fake materials and new means to attack biometric recognition systems. New unseen materials continuously challenge state-of-the-art spoofing detectors, suggesting for additional systematic approaches to target anti-spoofing. By incorporating liveness scores into the biometric fusion process, recognition accuracy can be enhanced, but traditional sum-rule based fusion algorithms are known to be highly sensitive to single spoofed instances. This paper investigates 1-median filtering as a spoofing-resistant generalised alternative to the sum-rule targeting the problem of partial multibiometric spoofing where m out of n biometric sources to be combined are attacked. Augmenting previous work, this paper investigates the dynamic detection and rejection of livenessrecognition pair outliers for spoofed samples in true multi-modal configuration with its inherent challenge of normalisation. As a further contribution, bootstrap aggregating (bagging) classifiers for fingerprint spoof-detection algorithm is presented. Experiments on the latest face video databases (Idiap Replay- Attack Database and CASIA Face Anti-Spoofing Database), and fingerprint spoofing database (Fingerprint Liveness Detection Competition 2013) illustrate the efficiency of proposed techniques.

Apical leaf necrosis as a defence mechanism against pathogen attack: effects of high nutrient availability on onset and rate of necrosis

An outdoor experiment was conducted to increase understanding of apical leaf necrosis in the presence of pathogen infection. Holcus lanatus seeds and Puccinia coronata spores were collected from two adjacent and otherwise similar habitats with differing long-term N fertilization levels. After inoculation, disease and necrosis dynamics were observed during the plant growing seasons of 2003 and 2006. In both years high nutrient availability resulted in earlier disease onset, a higher pathogen population growth rate, earlier physiological apical leaf necrosis onset and a reduced time between disease onset and apical leaf necrosis onset. Necrosis rate was shown to be independent of nutrient availability. The results showed that in these nutrient-rich habitats H. lanatus plants adopted necrosis mechanisms which wasted more nutrients. There was some indication that these necrosis mechanisms were subject to local selection pressures, but these results were not conclusive. The findings of this study are consistent with apical leaf necrosis being an evolved defence mechanism.

The costs and consequences of parasitoid attack for the predatory hoverfly, Episyrphus balteatus

Question: What are the life-history costs for a predatory insect of surviving parasitoid attack, and can parasitoid attack alter predator-prey interactions? Hypotheses: Survivorship is influenced by host age. Hosts that suffer parasitoid attack grow more slowly and consume fewer prey. Those that survive attack are smaller as adults and show reduced survivorship. Organisms: The aphidophagous hoverfly Episyrphus balteatus, its endoparasitoid wasp Diplazon laetatorius and its prey, the pea aphid, Acyrthosiphon pisum. Site of experiments: All experiments were conducted in controlled temperature rooms and chambers in the laboratory. Methods: Episyrphus balteatus larvae of each instar were exposed to attack by Diplazon laetatorius, then dissected to measure the encapsulation response (a measure of immunity). Second instar larvae were either attacked or not attacked by D. laetatorius. Their development rates and numbers of prey consumed were noted. The size and survivorship of surviving (immune) and control hoverflies were compared following eclosion. Conclusions: Successful immune response increased with larval age (first instar 0%, second instar 40%, third instar 100% survival). Second instar larvae that successfully resisted parasitoid attack were larger as pupae (but not as adults) and showed reduced adult survivorship. Female adult survivors were more likely than male survivors to have died within 16 days of eclosion, but there was no difference between unattacked male and female control hoverflies. Attacked larvae, irrespective of immune status, consumed fewer aphids than unattacked individuals. Episyrphus balteatus suffers significant costs of resisting parasitoid attack, and parasitoid attack can reduce the top-down effects of an insect predator, irrespective of whether the host mounts an immune response or not.

Aziridine synthesis via nucleophilic attack of carbene equivalents on imines: the aza-Darzens reaction

The development of new methods for the efficient synthesis of aziridines has been of considerable interest to researchers for more than 60 years, but no single method has yet emerged as uniformly applicable, especially for asymmetric synthesis of chiral aziridines. One method which has been intensely examined and expanded of late involves the nucleophilic addition to imines by anions bearing a-leaving groups; by analogy with the glycidate epoxide synthesis, these processes are often described as "aza-Darzens reactions". This Microreview gives a summary of the area, with a focus on contemporary developments. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

A tool for replay and analysis of gaze-enhanced multiparty sessions captured in immersive collaborative environments

A desktop tool for replay and analysis of gaze-enhanced multiparty virtual collaborative sessions is described. We linked three CAVE (TM)-like environments, creating a multiparty collaborative virtual space where avatars are animated with 3D gaze as well as head and hand motions in real time. Log files are recorded for subsequent playback and analysis Using the proposed software tool. During replaying the user can rotate the viewpoint and navigate in the simulated 3D scene. The playback mechanism relies on multiple distributed log files captured at every site. This structure enables an observer to experience latencies of movement and information transfer for every site as this is important fir conversation analysis. Playback uses an event-replay algorithm, modified to allow fast traversal of the scene by selective rendering of nodes, and to simulate fast random access. The tool's is analysis module can show each participant's 3D gaze points and areas where gaze has been concentrated.

Trade-off associated with selection for increased ability to resist parasitoid attack in Drosophila melanogaster

Costs of resistance are widely assumed to be important in the evolution of parasite and pathogen defence in animals, but they have been demonstrated experimentally on very few occasions. Endoparasitoids are insects whose larvae develop inside the bodies of other insects where they defend themselves from attack by their hosts' immune systems (especially cellular encapsulation). Working with Drosophila melanogaster and its endoparasitoid Leptopilina boulardi, we selected for increased resistance in four replicate populations of flies. The percentage of flies surviving attack increased from about 0.5% to between 40% and 50% in five generations, revealing substantial additive genetic variation in resistance in the field population from which our culture was established. In comparison with four control lines, flies from selected lines suffered from lower larval survival under conditions of moderate to severe intraspecific competition.

Pupal parasitoid attack influences the relative fitness of Drosophila that have encapsulated larval parasitoids

1. The evolution of host resistance to parasitoid attack will be constrained by two factors: the costs of the ability to defend against attack, and the costs of surviving actual attack. These factors have been investigated using Drosophila melanogaster and its parasitoids as a model system. The costs of defensive ability are expressed as a trade-off with larval competitive ability, whereas the costs of actual defence are exhibited in terms of reduced adult fecundity and size. 2. The costs of actual defence may be ameliorated by the host-choice decisions made by Pachycrepoideus vindemiae, a pupal parasitoid. If larvae that have successfully encapsulated a parasitoid develop into poorer quality hosts, then these may be rejected by ovipositing pupal parasitoids. 3. Pupae developing from larvae that have encapsulated the parasitoid Asobara tabida are smaller and have relatively thinner puparia. Thinner puparia are likely to be associated with a reduction in mechanical strength and possibly with a decrease in desiccation tolerance. 4. Pachycrepoideus vindemiae that develop in capsule-bearing pupae are smaller than those that emerge from previously unattacked hosts. This supports the prediction that ovipositing female P. vindemiae should avoid attacking capsule-bearing hosts. However, in choice experiments with 1-day-old pupae, P. vindemiae females oviposited preferentially in hosts containing a capsule, whereas there was no preference found with 4-day-old hosts. This appears to be a maladaptive host choice decision, as the female pupal parasitoids are preferentially attacking hosts that will result in a reduction of their own fitness. 5. The increased likelihood of attack by a pupal parasitoid is another cost of actual defence against larval parasitoid attack.

Influence of temperature on pea aphid Acyrthosiphon pisum (Hemiptera: Aphididae) resistance to natural enemy attack

The ability to resist or avoid natural enemy attack is a critically important insect life history trait, yet little is understood of how these traits may be affected by temperature. This study investigated how different genotypes of the pea aphid Acyrthosiphon pisum Harris, a pest of leguminous crops, varied in resistance to three different natural enemies (a fungal pathogen, two species of parasitoid wasp and a coccinellid beetle), and whether expression of resistance was influenced by temperature. Substantial clonal variation in resistance to the three natural enemies was found. Temperature influenced the number of aphids succumbing to the fungal pathogen Erynia neoaphidis Remaudiere & Hermebert, with resistance increasing at higher temperatures (18 vs. 28degreesC). A temperature difference of 5degreesC (18 vs. 23degreesC) did not affect the ability of A. pisum to resist attack by the parasitoids Aphidius ervi Haliday and A. eadyi Stary Gonzalez & Hall. Escape behaviour from foraging coccinellid beetles (Hippodamia convergens Guerin-Meneville) was not directly influenced by aphid clone or temperature (16 vs. 21degreesC). However, there were significant interactions between clone and temperature (while most clones did not respond to temperature, one was less likely to escape at 16degreesC), and between aphid clone and ladybird presence (some clones showed greater changes in escape behaviour in response to the presence of foraging coccinellids than others). Therefore, while larger temperature differences may alter interactions between Acyrthosiphon pisum and an entomopathogen, there is little evidence to suggest that smaller changes in temperature will alter pea aphid-natural enemy interactions.

Microbial impacts on plant-herbivore interactions: the indirect effects of a birch pathogen on a birch aphid

The role of indirect interactions in structuring communities is becoming increasingly recognised. Plant fungi can bring about changes in plant chemistry which may affect insect herbivores that share the same plant, and hence the two may interact indirectly. This study investigated the indirect effects of a fungal pathogen (Marssonina betulae) of silver birch (Betula pendula) on an aphid (Euceraphis betulae), and the processes underpinning the interaction. There was a strong positive association between natural populations of the aphid and leaves bearing high fungal infection. In choice tests, significantly more aphids settled on leaves inoculated with the fungus than on asymptomatic leaves. Individual aphids reared on inoculated leaves were heavier, possessed longer hind tibiae and displayed enhanced embryo development compared with aphids reared on asymptomatic leaves; population growth rate was also positively correlated with fungal infection when groups of aphids were reared on inoculated branches. Changes in leaf chemistry were associated with fungal infection with inoculated leaves containing higher concentrations of free-amino acids. This may reflect a plant-initiated response to fungal attack in which free amino acids from the degradation of mesophyll cells are translocated out of infected leaves via the phloem. These changes in plant chemistry are similar to those occurring during leaf senescence, and are proposed as the mechanistic basis for the positive interaction between the fungus and aphid.

Tracking larval insect movement within soil using high resolution X-ray microtomography

1. In contrast to above-ground insects, comparatively little is known about the behaviour of subterranean insects, due largely to the difficulty of studying them in situ. 2. The movement of newly hatched (neonate) clover root weevil (Sitona lepidus L. Coleoptera: Curculinidae) larvae was studied non-invasively using recently developed high resolution X-ray microtomography. 3. The movement and final position of S. lepidus larvae in the soil was reliably established using X-ray microtomography, when compared with larval positions that were determined by destructively sectioning the soil column. 4. Newly hatched S. lepidus larvae were seen to attack the root rhizobial nodules of their host plant, white clover (Trifolium repens L.). Sitona lepidus larvae travelled between 9 and 27 mm in 9 h at a mean speed of 1.8 mm h(-1). 5. Sitona lepidus larvae did not move through the soil in a linear manner, but changed trajectory in both the lateral and vertical planes.

Differentiating bone osteonal turnover rates by density fractionation; validation using the bomb C-14 atmospheric pulse

The density (BSG) of bone increases, at the osteon scale, during lifetime aging within the bone. In addition, post-mortem diagenetic change due to microbial attack produces denser bioapatite. Thus, fractionation of finely powdered bone on the basis of density should not only enable younger and older populations of osteons to be separated but also make it possible to separate out a less diagenetically altered component. We show that the density fractionation method can be used as a tool to investigate the isotopic history within an individual's lifetime, both in recent and archaeological contexts, and we use the bomb C-14 atmospheric pulse for validating the method.