The 3-D Structure of Polycrystalline Diamond Film by Electron Backscattering Diffraction (EBSD)

A lithographic method was used to produce polycrystalline diamond films having highly defined surface geometry, showing an array of diamond tips for possible application as a field emitter device. The films grown in this study used microwave plasma assisted chemical vapour deposition (MACVD) on a silicon substrate; the substrate was then dissolved away to reveal the surface features on the diamond film. It is possible to align the crystallite direction and affect the electron emission properties using a voltage bias to enhance the nucleation process and influence the nuclei to a preferred orientation. This study focuses on the identification of the distribution of crystal directions in the film, using electron backscattering diffraction (EBSD) to identify the crystallographic character of the film surface. EBSD allows direct examination of the individual diamond grains, grains boundaries and the crystal orientation of each individual crystallite. The EBSD maps of the bottom (nucleation side) of the films, following which a layer of film is ion-milled away and the mapping process repeated. The method demonstrates experimentally that oriented nucleation occurs and the thin sections allow the crystal texture to be reconstructed in 3-D. (C) 2003 Elsevier B.V. All rights reserved.

Identifiability and definiteness in Chinese

This article explores how the pragmatic notion of identfiability is encoded in Chinese. It presents a detailed analysis of the distinctive linguistic devices, including lexical, morphological, and position in sentence, which are employed in Chinese to indicate the interpretation of referents in respect of identifiability. Of the major determiners in Chinese, demonstratives are developing uses of a definite article, and yi 'one' + classier has developed uses of an indefinite article, although morphologically and in some cases also functionally they have not yet been fully grammaticalized. What makes Chinese further different from languages like English is the interpretation in this regard of what are called indeterminate lexical encodings, which include bare NPs and cardinality expressions. They by themselves are neutral in respect of the interpretation of identifiability. For indeterminate expressions, there is a strong but seldom absolute correlation between the interpretation of identiability or nonidentfiability and their occurrence in different positions in a sentence. Unlike the cases with several other languages without articles like Czech, Hindi, and Indonesian, the features of definiteness and indefiniteness cannot be obligatorily and uniquely specified for nominal expressions in Chinese. The findings in this article lead to the conclusion that definiteness as a grammatical category defined in the narrow sense has not been fully developed in Chinese.

Involvement of Islet-2 in the Slit signaling for axonal branching and defasciculation of the sensory neurons in embryonic zebrafish

In Drosophila melanogaster, Slit acts as a repulsive cue for the growth cones of the commissural axons which express a receptor for Slit, Roundabout (Robo), thus preventing the commissural axons from crossing the midline multiple times. Experiments using explant culture have shown that vertebrate Slit homologues also act repulsively for growth cone navigation and neural migration, and promote branching and elongation of sensory axons. Here, we demonstrate that overexpression of Slit2 in vivo in transgenic zebrafish embryos severely affected the behavior of the commissural reticulospinal neurons (Mauthner neurons), promoted branching of the peripheral axons of the trigeminal sensory ganglion neurons, and induced defasciculation of the medial longitudinal fascicles. In addition, Slit2 overexpression caused defasciculation and deflection of the central axons of the trigeminal sensory ganglion neurons from the hindbrain entry point. The central projection was restored by either functional repression or mutation of Robo2, supporting its role as a receptor mediating the Slit signaling in vertebrate neurons. Furthermore, we demonstrated that Islet-2, a LIM/homeodomain-type transcription factor, is essential for Slit2 to induce axonal branching of the trigeminal sensory ganglion neurons, suggesting that factors functioning downstream of Islet-2 are essential for mediating the Slit signaling for promotion of axonal branching. (C) 2004 Elsevier Ireland Ltd. All rights reserved.

Adjustment of chldren who have a sibling with Down syndrome: perspectives of mothers, fathers and children

Background A number of methodological weaknesses have contributed to our relatively poor understanding of the impact on children of having a brother or sister with a disability. These include a focus on poor adjustment, using multidiagnostic groups, inadequate matching, and a failure to consider the perspectives of children and parents together. Method This study compared the adjustment of 53 siblings of a child with Down syndrome with a comparison group of siblings of children who were developing typically. Children were matched on a case-by-case basis for gender, age and position in family. Families were matched for family size and father's occupation. The age range of the target siblings was 7-14 years. Data were gathered from mothers, fathers and siblings. Results There were no significant differences between the groups on adjustment measures. These included parent perceptions of externalizing and internalizing behaviours, parent perceptions of sibling competence, and sibling perceptions of their own competence and self-worth. Associations between measures of adjustment and child reports of their contribution to household functioning depended on sex rather than group membership. There was an association between parental reports of externalizing behaviour and sibling relationships with the brother/sister closest in age. Conclusions Having a brother or sister with Down syndrome does not inevitably lead to poor adjustment. Examination of within-family processes would appear to be more useful in identifying children at risk than merely group membership.

Effect of anode material and cavity design on the performance of microcavity OLEDs

We report on the effect of the replacement of the conventional ITO anode with the semitransparent metallic material on the performance of microcavity OLEDs. We performed comprehensive simulations of the emission from microcavity OLEDs consisting of widely used organic materials, N,N′-di(naphthalene-1- yl)-N,N′-diphenylbenzidine (NPB) as a hole transport layer and tris (8-hydroxyquinoline) (Alq3) as emitting and electron transporting layer. Silver and LiF/Al were considered as a cathode, while metallic (Au and Ag) anode was used and simulations were performed on devices with both the metallic and conventional ITO anode. The electroluminescence emission spectra, electric field distribution inside the device, carrier density, recombination rate and exciton density were calculated as a function of the position of the emission layer. The results show that the metallic anode enhances light output and that optimum emission from a microcavity OLED is achieved when the position of the recombination region is aligned with the antinode of the standing wave inside the cavity. The microcavity OLED devices with Ag/Ag and Ag/Au mirrors were fabricated and characterized. The experimental results have been compared to the simulations and the influence of the different anode, emission region width and position on the performance of microcavity OLEDs was discussed.

UQ RoboRoos: Achieving power and agility in a small size robot

The UQ RoboRoos have been developed to participate in the RoboCup robot soccer small size league over several years. RoboCup 2001 saw a focus on the mechanical design of the RoboRoos, with the introduction of an omni-directional drive system and a high power kicker. The change in mechanical design had implications for the rest of the system particularly navigation and multi-robot planning. In addition, the overhead vision system was upgraded to improve reliability and robustness.

Revision of Affecauda Hall & Chambers, 1999 (Digenea: Gyliauchenidae Fukui, 1929), including the description of two new species from fishes of the Indo-West Pacific

We describe 2 new species of Affecauda from the intestine of acanthuroid fishes of the Indo-West Pacific. Affecauda rugosa n. sp. is described from 1 mature specimen in excellent condition and 1 immature fractured specimen from the intestine of the sailfin tang, Zebrasoma veliferum (Acanthuridae), from Noumea, New Caledonia. Affecauda salacia n. sp. is described from the intestine of the ocellated spinefoot, Siganus corallinus (Siganidae), from Lizard Island, Great Barrier Reef, Queensland, Australia. Each of these species is made distinct from the type-species, Affecauda annulata Hall & Chambers, 1999, by combinations of the extent of tegumental annulations, conformation of the oesophagus and position of the ovary. The description of 2 new species of Affecauda necessitates a revision of the generic diagnosis, which is here amended to incorporate the additional species. A key to species is provided. The description of further species of Affecauda from waters external to the Great Barrier Reef and from siganid fishes expands the biogeographical range for species of Affecauda, from species of Naso on the Great Barrier Reef, to acanthuroid fishes of the western Pacific.

Marine actinomycetes related to the 'Salinospora' group from the Great Barrier Reef sponge Pseudoceratina clavata

Ten strains identified as marine actinomycetes related to the 'Salinospora ' group previously reported only from marine sediments were isolated from the Great Barrier Reef marine sponge Pseudoceratina clavata. The relationship of the isolates to 'Salinospora' was confirmed by phylogenetic analysis of 16S rRNA gene sequences. Colony morphology and pigmentation, occurrence and position of spores, and salinity requirements for growth were all consistent with this relationship. Genes homologous to beta-ketosynthase, an enzyme forming part of a polyketide synthesis complex, were retrieved from these isolates; these genes shared homology with other Type I ketosynthase genes, and phylogenetic comparison with amino acid sequences derived from database beta-ketosynthase genes was consistent with the close relationship of these isolates to the actinomycetes. Primers based on 16S rRNA gene sequences and designed for targeting amplification of members of the 'Salinospora' group via polymerase chain reaction have been used to demonstrate occurrence of these actinomycetes within the sponge tissue. In vitro bioassays of extracts from the isolates for antibiotic activity demonstrated that these actinomycetes have the potential to inhibit other sponge symbionts in vivo, including both Gram-negative and Gram-positive bacteria.

New Thelastomatoidea (Nematoda : Oxyurida) from Australian burrowing cockroaches (Blaberidae : Geoscapheinae, Panesthiinae)

Four new species and two new genera of thelastomatoid are described from several species of Australian burrowing cockroaches (Blattodea: Panesthiinae; Geoscapheinae). Corpicracens munozae n. g., n. sp., Pseudodesmicola botti n. g., n. sp. and Cephalobellus nolani n. sp. are described from Geoscapheus dilatatus (Blattodea: Geoscapheinae) from Mendooran, New South Wales; one new thelastomatid, Blattophila praelongicauda n. sp., is described from Panesthia cribrata from Lamington National Park, Queensland. Corpicracens munozae n. g., n. sp. is long and slender, with a monodelphic female reproductive system, a clavate corpus with a slight posterior pseudobulb, oval eggs flattened at the poles, and a relatively robust, subulate tail. Pseudodesmicola botti n. g., n. sp. is slightly more robust in body, also has a monodelphic reproductive system, a cylindrical corpus with a posterior pseudobulb, ovoid eggs and a very long, subulate tail. Cephalobellus nolani n. sp. is distinguished from other members of the genus by its relatively short and broad body and egg shape. Lastly, Blattophila praelongicauda n. sp. is distinguished from other members of the genus by having eggs with a single, polar operculum, tail length, and position of the vulva, nerve ring and excretory pore. An additional species, known by a single specimen from Panesthia tryoni tryoni from the same locality is characterised but not named. The species found are all relatively rare parasites of Australian burrowing cockroaches, each having a prevalence of less than 10%.

A magnetization mapping approach for passive shim design in MRI

A new passive shim design method is presented which is based on a magnetization mapping approach. Well defined regions with similar magnetization values define the optimal number of passive shims, their shape and position. The new design method is applied in a shimming process without prior-axial shim localization; this reduces the possibility of introducing new errors. The new shim design methodology reduces the number of iterations and the quantity of material required to shim a magnet. Only a few iterations (1-5) are required to shim a whole body horizontal bore magnet with a manufacturing error tolerance larger than 0.1 mm and smaller than 0.5 mm. One numerical example is presented