Detection of sub-tidal mussel beds on rocky reefs using acoustics

The collection of recently settled wild mussels from beach-cast seaweed provides the seed for a large and rapidly expanding mussel aquaculture industry in New Zealand, but the locations of adult populations producing this seed are unknown. Traditional methods of assessing sub-tidal habitats of rocky reefs (diver census, video camera drops) are neither cost-effective nor practical for the relatively large spatial scales involved. Remote sensing tools offer solutions to this problem. We tested the ability of the acoustic seafloor classification system, Quester Tangent Corporation (QTC) Impact, to detect the presence of green-lipped mussel (Perna canaliculus) populations on sub-tidal rocky reefs. Acoustic data were collected from a range of visual subtidal habitats, combined, and analysed using QTC Impact's principal component analysis and clustering software. Discriminant function analysis assessed whether visually distinctive habitats could be correctly classified using this acoustic data only. Consistent and reliable classifications were found for continuous mussel beds (100% correct, 0% misclassification from other habitat types), and sand, while the other various classes of rocky reef habitats (i.e. reef with varying levels of biological cover of kelps and encrusting invertebrates, including occasional mussel patches at one site) were identifiable to a general class of rocky reef, without significant mussel cover. These results demonstrate that QTC Impact can reliably discriminate subtidal mussel beds on rocky reefs from other habitats, making it feasible to proceed with large-scale mapping.     

User Preference for a Control-Based Reduced Processing Decision Support Interface

This study examined trainee crime-scene investigators' preference for, and accuracy in using, four different computer-based decision support interface designs, each of which incorporated a different reduced processing information acquisition strategy. The interfaces differed on the basis of the number of options that could be considered simultaneously and the level of control that could be exercised over the number and sequence in which feature values were accessed. Forty trainee investigators completed six decision scenarios in which they were asked to acquire information and formulate a decision by selecting one of three options. The study comprised two phases, the first of which involved familiarizing participants with each of the four interface designs and collecting performance and subjective data. The second phase involved trainees selecting one of the four interfaces to engage in a fifth and sixth decision scenario involving high or low levels of time-pressure. The results indicated that the “all options, full control” interface was the preferred option in the low time-pressure condition. Although the strategy remained the most frequently selected in the high time-pressure condition, this preference was not significant. It was concluded that the perceptions of difficulty and the degree of user control over information acquisition were more important than perceived efficiency in the selection of computer-based interface designs. The outcomes have implications for the design of decision support systems.     

Disquiet in the plasma

The metaphor of plasma is taken up to present and discuss movement and engagement by participants in mixed reality installation arts. Two works involving full body video portraits exhibited through large plasma screens in a variety of public settings are covered. Machinic mediations of video realism are considered in terms of embodied interaction in which viewer-participants contribute to the ‘disquiet’ of gendered figuring. Processural, proximal and personal aspects of responsive engagement are discussed. This is extended to performativity that may lead us to critical reflection of our own actions and responses in mixed reality arts.     

A prototype scanning stylus profilometer for rapid measurement of small surface areas

A novel stylus based profiling instrument has been developed for rapid measurement of small surface areas. Outlined in the following paper are some of the key features of the prototype system including the wideband stylus pick-up and the dedicated scanning traverse mechanism. In addition, some preliminary results obtained by scanning the instrument over several different surfaces are presented.     

Effects of ion irradiation on fatigue of Fe-12Cr-20Mn stainless steel for fusion reactor applications

To minimize waste disposal problems associated with the residual radioactivity of the first wall material of a fusion reactor, fast induced radioactive decay (FIRD) alloys based on the Fe-Cr-Mn system are being investigated. The objective of this research was to evaluate the effects of irradiation on cyclic strain localization and fatigue crack initiation in a FIRD Fe-12Cr-20Mn alloy and to compare the response to commercially available 316 stainless steel. The alloys were irradiated with 200 keV Fe ions to a dose of 1 x 10 ions/cm² and 15.5 keV He ions to a dose of 7 x 10¹⁵ ions/cm² to simulate the irradiation-induced defect structure and helium concentration that would be produced in a fusion reactor. Irradiated specimens were fatigued in a cantilever beam fatigue testing machine with the deflection set to produce a fully reversed total strain amplitude of 0.25% on the surface of the specimen. Acetate replicas were obtained during the fatigue tests to provide a record of surface fatigue damage. Transmission electron microscopy (TEM) analyses were performed to characterize the microstructural changes resulting from the irradiations and interactions between fatigue-induced glide dislocations and the irradiation-induced defects. Results indicate that the irradiated Fe-Cr-Mn alloy exhibits fatigue properties similar to 316 stainless steel. Glide dislocations produced by fatigue cycling annihilate irradiation-induced defects. The defect annihilation causes the formation of cleared channels in which the cyclic plastic strain is localized. Subsurface slip bands penetrate the irradiated regions through the cleared channels and serve as fatigue crack initiation sites.     

Microstructures and mechanical properties of welded Fe-12Cr-20Mn austenitic stainless steel

The effects of welding on the tensile and fatigue properties of fully annealed and cold-worked Fe-12Cr-20Mn austenitic stainless steel were evaluated. Room temperature and 500 °C tensile tests and room temperature cantilever beam fatigue tests were accomplished on specimens that contained autogenous bead-on-plate welds. The tensile and fatigue properties of the fully annealed material were not significantly influenced by welding. The tensile properties of the welded cold-worked material were also not significantly affected by the presence of a weldment. However, welding caused a large reduction of the fatigue life of the cold-worked material. Fatigue cracks preferentially initiated at large Mn-Si inclusions that formed in the fusion zones of the weldments.     

Melanin Distribution in Human Skin: Influence of Cytoskeletal,Polarity, and Centrosome-Related Machinery of Stratum basale Keratinocytes

Melanin granules cluster within supra-nuclear caps in basal keratinocytes (KCs) of the human epidermis, where they protect KC genomic DNA against ultraviolet radiation (UVR) damage. While much is known about melanogenesis in melanocytes (MCs) and a moderate amount about melanin transfer from MC to KC, we know little about the fate of melanin once inside KCs. We recently reported that melanin fate in progenitor KCs is regulated by rare asymmetric organelle movement during mitosis. Here, we explore the role of actin, microtubules, and centrosome-associated machinery in distributing melanin within KCs. Short-term cultures of human skin explants were treated with cytochalasin-B and nocodazole to target actin filaments and microtubules, respectively. Treatment effects on melanin distribution were assessed by the Warthin–Starry stain, on centrosome-associated proteins by immunofluorescence microscopy, and on co-localisation with melanin granules by brightfield microscopy. Cytochalasin-B treatment disassembled supra-nuclear melanin caps, while nocodazole treatment moved melanin from the apical to basal KC domain. Centrosome and centriolar satellite-associated proteins showed a high degree of co-localisation with melanin. Thus, once melanin granules are transferred to KCs, their preferred apical distribution appears to be facilitated by coordinated movement of centrosomes and centriolar satellites. This mechanism may control melanin’s strategic position within UVR-exposed KCs.     

The effects of saponin,antimony and glue on zinc electrowinning from Kidd Creek electrolyte

The effects of Saponin alone and in combination with antimony and glue on zinc deposition current efficiency and polarization and on the morphology and orientation of 6h and 24h zinc deposits electrowon at 500 A m^–2 and 38°C from Kidd Creek zinc electrolyte were determined. Saponin, at concentrations to 100mgl^–1, was weakly polarizing, changed the preferred deposit orientation from basal to intermediate and decreased the current efficiency. At optimum glue + antimony levels, Saponin concentrations 5mgl^–1 resulted in an increase in zinc deposition current efficiency and consistently gave either a <114><112><103><102><101> or a <101><112> preferred deposit orientation depending on the antimony + glue combination used. Tests run for 24h for selected combinations of Saponin, antimony and glue confirmed the results obtained for the 6h studies.     

Length preferences and periodicity in {beta}-strands. Antiparallel edge {beta}-sheets are more likely to finish in non-hydrogen bonded rings

We analysed the length distributions of different types of ß-strandin a high resolution, non-homologous set of 500 protein structures,finding differences in their mean lengths. Antiparallel edgestrands in strand–turn–strand motifs show a preferencefor an even number of residues. This propensity is enhancedif the length is corrected for ß-bulges, which insertan extra residue into the strand. Residues in antiparallel edgeß-strands alternate between being in hydrogen bondedand non-hydrogen bonded rings. Antiparallel edges with an evennumber of residues are more likely to have their final ßresidue in a non-hydrogen bonded ring. This suggests that non-hydrogenbonded rings are intrinsically more stable than hydrogen bondedrings, perhaps because its side chain packing is closer. Therefore,we suggest that a simple way to increase ß-hairpinstability, or the stability of an antiparallel edge strand,is to have a non-hydrogen bonded ring at the end of the strand. Received June 19, 2003; revised October 25, 2003; accepted November 7, 2003