Residential sorting across Auckland neighbourhoods

This paper addresses the extent to which people in Auckland exhibit residential location patterns that differ between groups, i.e. the extent to which they are spatially sorted. To measure patterns of residential location, the paper uses the index of segregation, an isolation index, Gini coefficients, Ellison & Glaeser and Maurel & Sédillot concentration measures, Moran’s I and Getis and Ord’s G*. Results are presented based on a classification of the population in different ways: ethnicity, income, education, age and country of birth. Both city-wide and local measures are considered. We find that ethnic-based sorting is the strongest indicator of residential sorting patterns, but soring by income, education and age is also present. Sorting by income and qualifications is strongest at the top and, to lesser extent, at the bottom of the income and qualifications range. Age segregation is most pronounced for older residents. Clustering is strongest within a range of up to one kilometre and declines significantly over greater distances. Local analysis by means of Getis and Ord’s G* calculations suggest significant ethnic clustering. Apart from Maori and Pacific Islanders, ethnic groups tend to locate way from each other, as confirmed with cross-Moran’s I calculations. When considering interactions between ethnicity and income we find that the location of ethnicity income subgroups is more strongly related to neighbourhood income

Nanomechanical properties of few-layer graphene membranes

We have measured the mechanical properties of few-layer graphene and graphite flakes that are suspended over circular holes. The spatial profile of the flake's spring constant is measured with an atomic force microscope. The bending rigidity of and the tension in the membranes are extracted by fitting a continuum model to the data. For flakes down to eight graphene layers, both parameters show a strong thickness-dependence. We predict fundamental resonance frequencies of these nanodrums in the GHz range based on the measured bending rigidity and tension.Comment: 9 pages, 3 figures, This article has been accepted by Appl. Phys. Lett. After it is published, it will be found at http://apl.aip.org

Discrete-time quadrature feedback cooling of a radio-frequency mechanical resonator

We have employed a feedback cooling scheme, which combines high-frequency mixing with digital signal processing. The frequency and damping rate of a 2 MHz micromechanical resonator embedded in a dc SQUID are adjusted with the feedback, and active cooling to a temperature of 14.3 mK is demonstrated. This technique can be applied to GHz resonators and allows for flexible control strategies.Comment: To appear in Appl. Phys. Let

Tunable backaction of a dc SQUID on an integrated micromechanical resonator

We have measured the backaction of a dc superconducting quantum interference device (SQUID) position detector on an integrated 1 MHz flexural resonator. The frequency and quality factor of the micromechanical resonator can be tuned with bias current and applied magnetic flux. The backaction is caused by the Lorentz force due to the change in circulating current when the resonator displaces. The experimental features are reproduced by numerical calculations using the resistively and capacitively shunted junction (RCSJ) model.Comment: Submitted to Phys. Rev. Let

Nonlinear modal interactions in clamped-clamped mechanical resonators

A theoretical and experimental investigation is presented on the intermodal coupling between the flexural vibration modes of a single clamped-clamped beam. Nonlinear coupling allows an arbitrary flexural mode to be used as a self-detector for the amplitude of another mode, presenting a method to measure the energy stored in a specific resonance mode. Experimentally observed complex nonlinear dynamics of the coupled modes are quantitatively captured by a model which couples the modes via the beam extension; the same mechanism is responsible for the well-known Duffing nonlinearity in clamped-clamped beams.Comment: 5 pages, 3 figure

Fibre-reinforced polymer strengthening of substandard lap-spliced reinforced concrete members: A comprehensive survey

Externally bonded Fibre Reinforced Polymer (FRP) confinement is extensively used to improve the bond strength of substandard lap spliced steel bars embedded in reinforced concrete (RC) components. However, the test results from bond tests on such bond-deficient components are not fully conclusive, which is reflected in the few design guidelines available for FRP strengthening. For the first time, this article presents a comprehensive survey on FRP strengthening of substandard lap-spliced RC members, with emphasis on the adopted experimental methodologies and analytical approaches developed to assess the effectiveness of FRP in controlling bond-splitting failures. The main findings and shortcomings of previous investigations are critically discussed and further research needs are identified. This review contributes towards the harmonisation of testing procedures so as to facilitate the development of more accurate predictive models, thus leading to more cost-effective strengthening interventions

Polyphasic re-examination of Debaryomyces hansenii strains and reinstatement of D. hansenii, D. fabryi and D. subglobosus

The type species of the genus Debaryomyces, Debaryomyces hansenii, is a highly heterogeneous species. It has been isolated from a large diversity of natural sources including fruit, air, water, soil, but most frequently from processed food products. The species delineation of this yeast species urgently needs clarification. The heterogeneity in taxonomic characteristics has resulted in the description of varieties linked to D. hansenii. The aim of this study was to re-examine and classify D. hansenii using a polyphasic approach. A total of 65 D. hansenii isolates were examined, 57 representing the variety hansenii and nine the variety fabryi. The selection of strains for DNA reassociation and phylogenetic analysis was based on polymerase chain reaction mediated fingerprints using four mini- and microsatellite-specific primers. The discriminating power of growth at 35 °C and 37 °C was re-examined and ascospore production was observed. DNA reassociations and phylogenetic analyses were performed on selected isolates from each of the clusters obtained from the DNA fingerprint analyses. The data indicated the presence of three distinct species within the D. hansenii group, which were represented by type strains of former species and that are proposed to be reinstated: D. hansenii (CBS 767T = MUCL 49680T), D. fabryi (CBS 789T = MUCL 49731T) and D. subglobosus (CBS 792T = MUCL 49732T)

The biochemical basis of changes in normal and mutant human skin fibroblasts during ageing in culture : an investigation into the free radical theory of ageing

From the pattern of inheritance of normal ageing, this process inevitably results from either abnormal aggregation of subunits of enzymes, abnormal feedback inhibition of enzymes, receptor mutations, membrane defects, or deposition of abnormal fibrillar proteins (Vogel and Motulsky, 1986). The process of ageing should, due to the principle of universality, occur at a site common to all cells : general metabolism, chromatin structure and function ( eg. DNA replication and gene expression) or the physiology of the membrane. The cell type to be studied should be fully functional as to these three sites, and the theories potentially able to explain the ageing process should all encompass changes at any of these aspects . of cellular function. The system to be used throughout this thesis is the cultured human skin fibroblast, which still expresses genes, replicates DNA, has a general metabolism and has functional membranes. This cell type alos undergoes a loss of proliferative potential both in vivo and in culture (Martin et al.,1970). Furthermore, any kind of a phenotype expressed in fibroblast-like cells can theoretically be used for prenatal diagnosis of human genotypes (eg. Werner's syndrome and Spielmeyer-Vogt syndrome). The following postulates can be derived now. First, free radicals should cause the accumulation of lipid peroxides or decay products, which should further yield to the accumulation of autofluorescence. Second, free radicals, or the reactive products resulting from them should impair cellular proliferation to the extent as to cause an irreversible growth arrest of initially dividing cells. Third, crosslinking of proteins by reactive breakdown products of lipid peroxides should occur. Fourth, the capacity of the systems implied in the detoxification of free radicals, or the reactive products thereof, should decrease in capacity during ageing of cultured cells