15,978 research outputs found

    Can the mana of Maori men who sexually abuse children be restored?

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    The problem of child sex abuse is prevalent across all segments of society, and Maori, unfortunately, are overrepresented in this problem. In the total prison population of 6591, 13.6% are identified as child sex offenders. Of the 3,299 Maori in prison 283 (8.5%) are identified as child sex offenders whereas 631 (18.6%) of the 3292 non-Maori have been so identified. However, Maori only represent approximately 15% of the general population. In proportionate terms, approximately one of every 970 Maori men is currently in prison for child sex offences, while for non-Maori that figure is one in 31251. Also, disclosures from offenders suggest that sexual abuse is particularly common in rural or disadvantaged areas, with offenders frequently reporting being abused by multiple offenders and being aware of chronic abuse, little of which was ever reported

    The Density Spike in Cosmic-Ray-Modified Shocks: Formation, Evolution, and Instability

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    We examine the formation and evolution of the density enhancement (density spike) that appears downstream of strong, cosmic-ray-modified shocks. This feature results from temporary overcompression of the flow by the combined cosmic-ray shock precursor/gas subshock. Formation of the density spike is expected whenever shock modification by cosmic-ray pressure increases strongly. That occurence may be anticipated for newly generated strong shocks or for cosmic-ray-modified shocks encountering a region of higher external density, for example. The predicted mass density within the spike increases with the shock Mach number and with shocks more dominated by cosmic-ray pressure. We find this spike to be linearly unstable under a modified Rayleigh-Taylor instability criterion at the early stage of its formation. We confirm this instability numerically using two independent codes based on the two-fluid model for cosmic-ray transport. These two-dimensional simulations show that the instability grows impulsively at early stages and then slows down as the gradients of total pressure and gas density decrease. Observational discovery of this unstable density spike behind shocks, possibly through radio emission enhanced by the amplified magnetic fields would provide evidence for the existence of strongly cosmic-ray modified shock structures.Comment: 26 pages in Latex and 6 figures. Accepted to Ap

    Epistemology and conceptual resources for the development of learning technologies

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    The issues raised by the design and development of technologies to enhance learning has led to a demand for an appropriate language and form of conceptualisation. However we are insufficiently familiar with the way in which different types of mediated tool use occur, to develop the theoretical models needed for the development of this language and form of conceptualisation. In its absence a somewhat eclectic variety of concepts and research, such as the concept of affordance, are recruited in accounts of learning with new technologies. In looking briefly at the relevant area in philosophy this paper will consider whether or not the use of concepts such as affordance give adequate weight to social practice, meaning and knowledge in the design of educational technology. A fruitful source for work in this field which has not been sufficiently exploited is philosophy, particularly recent work in epistemology

    The origin of deep ocean microseisms in the North Atlantic Ocean

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    Oceanic microseisms are small oscillations of the ground, in the frequency range of 0.05–0.3 Hz, associated with the occurrence of energetic ocean waves of half the corresponding frequency. In 1950, Longuet-Higgins suggested in a landmark theoretical paper that (i) microseisms originate from surface pressure oscillations caused by the interaction between oppositely travelling components with the same frequency in the ocean wave spectrum, (ii) these pressure oscillations generate seismic Stoneley waves on the ocean bottom, and (iii) when the ocean depth is comparable with the acoustic wavelength in water, compressibility must be considered. The efficiency of microseism generation thus depends on both the wave frequency and the depth of water. While the theory provided an estimate of the magnitude of the corresponding microseisms in a compressible ocean, its predictions of microseism amplitude heretofore have never been tested quantitatively. In this paper, we show a strong agreement between observed microseism and calculated amplitudes obtained by applying Longuet-Higgins' theory to hindcast ocean wave spectra from the North Atlantic Ocean. The calculated vertical displacements are compared with seismic data collected at stations in North America, Greenland, Iceland and Europe. This modelling identifies a particularly energetic source area stretching from the Labrador Sea to south of Iceland, where wind patterns are especially conducive to generating oppositely travelling waves of same period, and the ocean depth is favourable for efficient microseism generation through the ‘organ pipe’ resonance of the compression waves, as predicted by the theory. This correspondence between observations and the model predictions demonstrates that deep ocean nonlinear wave–wave interactions are sufficiently energetic to account for much of the observed seismic amplitudes in North America, Greenland and Iceland

    Pick-up ion dynamics at the structured quasi-perpendicular shock

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    We study the pickup ion dynamics and mechanism of multiple reflection and acceleration at the structured quasi-perpendicular supercritical shock. The motion of the pickup ions in the shock is studied analytically and numerically using the test particle analysis in the model shock front. The analysis shows that slow pickup ions may be accelerated at the shock ramp to high energies. The maximum ion energy is determined by the fine structure of the electro-magnetic field at the shock ramp and decreases when the angle between magnetic field and shock normal decreases. Evolution of pickup ion distribution across the nearly-perpendicular shock and pickup ion spectrum is also studied by direct numerical analysis.Comment: LaTeX (elsart.cls), packages: times,amsmath,amssymb; 15 pages + 13 figures (GIF). To appear in Planetary and Space Science

    Are ideas getting harder to find?

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    In many growth models, economic growth arises from people creating ideas, and the long-run growth rate is the product of two terms: the effective number of researchers and their research productivity. We present a wide range of evidence from various industries, products, and firms showing that research effort is rising substantially while research productivity is declining sharply. A good example is Moore’s Law. The number of researchers required today to achieve the famous doubling every two years of the density of computer chips is more than 18 times larger than the number required in the early 1970s. Across a broad range of case studies at various levels of (dis)aggregation, we find that ideas—and in particular the exponential growth they imply — are getting harder and harder to find. Exponential growth results from the large increases in research effort that offset its declining productivit

    Does a Carbonatite Deposit Influence Its Surrounding Ecosystem?

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    Carbonatites are unusual alkaline rocks with diverse compositions. Although previous work has characterized the effects these rocks have on soils and plants, little is known about their impacts on local ecosystems. Using a deposit within the Great Lakes–St. Lawrence forest in northern Ontario, Canada, we investigated the effect of a carbonatite on soil chemistry and on the structure of plant and soil microbial communities. This was done using a vegetation survey conducted above and around the deposit, with corresponding soil samples collected for determining soil nutrient composition and for assessing microbial community structure using 16S/ITS Illumina Mi-Seq sequencing. In some soils above the deposit a soil chemical signature of the carbonatite was found, with the most important effect being an increase in soil pH compared with the non-deposit soils. Both plants and microorganisms responded to the altered soil chemistry: the plant communities present in carbonatite-impacted soils were dominated by ruderal species, and although differences in microbial communities across the surveyed areas were not obvious, the abundances of specific bacteria and fungi were reduced in response to the carbonatite. Overall, the deposit seems to have created microenvironments of relatively basic soil in an otherwise acidic forest soil. This study demonstrates for the first time how carbonatites can alter ecosystems in situ

    Laser frequency comb techniques for precise astronomical spectroscopy

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    Precise astronomical spectroscopic analyses routinely assume that individual pixels in charge-coupled devices (CCDs) have uniform sensitivity to photons. Intra-pixel sensitivity (IPS) variations may already cause small systematic errors in, for example, studies of extra-solar planets via stellar radial velocities and cosmological variability in fundamental constants via quasar spectroscopy, but future experiments requiring velocity precisions approaching ~1 cm/s will be more strongly affected. Laser frequency combs have been shown to provide highly precise wavelength calibration for astronomical spectrographs, but here we show that they can also be used to measure IPS variations in astronomical CCDs in situ. We successfully tested a laser frequency comb system on the Ultra-High Resolution Facility spectrograph at the Anglo-Australian Telescope. By modelling the 2-dimensional comb signal recorded in a single CCD exposure, we find that the average IPS deviates by <8 per cent if it is assumed to vary symmetrically about the pixel centre. We also demonstrate that series of comb exposures with absolutely known offsets between them can yield tighter constraints on symmetric IPS variations from ~100 pixels. We discuss measurement of asymmetric IPS variations and absolute wavelength calibration of astronomical spectrographs and CCDs using frequency combs.Comment: 11 pages, 7 figures. Accepted for publication in MNRA

    Improving health and education outcomes for children in remote communities: A cross-sector and developmental evaluation approach

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    Early childhood is one of the most influential developmental life stages. Attainments at this stage will have implications for the quality of life children experience as they transition to adulthood. Children residing in remote Australia are exposed to socioeconomic disadvantage that can contribute to developmental delays and resultant poorer education and health outcomes. Complex contributing factors in far west New South Wales have resulted in children with speech and fine motor skill delays experiencing no to limited access to allied health services for a number of decades. More recently, growing awareness that no single policy, government agency, or program could effectively respond to these complexities or ensure appropriate allied health service access for children in these communities has led to the development of the Allied Health in Outback Schools Program, which has been operational since 2009. The program is underpinned by cross-sector partnerships and a shared aspirational aim to improve the developmental outcomes of children to enhance their later life opportunities. It was identified early that the initiative had the potential to deliver mutually beneficial outcomes for communities and participating partner organisations.Over the last five years the program has been the catalyst for partnership consolidation, expansion and diversification. The developmental evaluation approach to continuous program adaptation and refinement has provided valuable insights that have informed health and education policy and enabled the program to be responsive to changing community needs, emerging policy and funding reforms.This article explores the evolution of the program partnerships, their contribution to program success and longevity, and their capacity to respond to an emergent and dynamic environment. The authors propose that a community-centred and developmental approach to program innovation and implementation in remote locations is required. This is based on the premise that contemporary linear, logic-based policy development and funding allocations, with predetermined program deliverables and outcomes, are no longer capable of responding appropriately to the complexities experienced by remote communities.Keywords: allied health, remote communities, cross-sectoral partnerships, service learnin
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