350 research outputs found

    A new direction for water management? Indigenous nation building as a strategy for river health

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    © 2017 by the author(s). Indigenous involvement in Australian water management is conventionally driven by a top-down approach by nonIndigenous government agencies, that asks “how do we engage Indigenous people?” and has culminated in the ineffective “consult” and “service delivery” processes evident in mainstream water management planning. This is a hopeful paper that identifies the critical importance of a “nation-based” approach for effective Indigenous engagement in water planning and policy through the work undertaken by the Ngarrindjeri Regional Authority (NRA) in the Murray Futures program. The NRA is an Indigenous government in the “settled-south” of Australia. Over past decades, the NRA has developed a range of political technologies that act as tools for redeveloping Ngarrindjeri Nationhood after colonial disempowerment and dispossession. These tools enable better collaboration with nonIndigenous governments, especially in natural resource management policy and practice. In turn, this has better enabled the NRA to exercise a decision-making and planning authority over the lands and waters in its jurisdiction, therefore, more effectively exercising its ongoing duty of care as Country. This paper presents a case study of the Sugar Shack Complex Management Plan, codeveloped by the NRA and the South Australian Government in 2015, to demonstrate the benefits that accrue when Indigenous nations are resourced as authorities responsible for reframing water management and planning approaches to facilitate the equitable collaboration of Indigenous and nonIndigenous worldviews. As a marker of the success of this strategy, the Ngarrindjeri Yarluwar-Ruwe Program, in partnership with the South Australian government, recently won the Australian Riverprize 2015 for delivering excellence in Australian river management

    Speaking as Country: A Ngarrindjeri Methodology of Transformative Engagement

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    The systemic nature of colonisation results in a trenchant series of problems for Indigenous peoples striving to protect their lands and waters, to ensure the health of their communities, and to rightfully enjoy their cultural life. Indigenous leaders and communities who seek the transformation of colonial systems of knowledge, law and practice must engage effectively and authoritatively with the non-Indigenous processes and structures that have long been the source of Indigenous disempowerment. How can Indigenous people engage with a dominant system, without being co-opted into that system? Similar issues are raised for non-Indigenous actors implicated with Indigenous affairs: how can the agencies of a dominant system partner meaningfully and respectfully with Indigenous peoples, to refrain from appropriating Indigenous cultural knowledge and assimilating Indigenous aspirations within a framework that has been developed insensitively, in ignorance of Indigenous needs, perspectives and philosophies? In sum, how can we collectively ensure that our ‘response to wrongs are not reinscriptions of colonial processes’?3 In South Australia, the Ngarrindjeri Regional Authority (NRA) has developed an innovative response to colonial governmentality, which subverts and seeks to correct the structural conditions underlying the continuing dominance of colonial social forms and their associated epistemologies. The NRA makes strategic use of an Indigenous-led methodology of engagement that is culturally relevant and secured legally through contractual agreement.4 At its centre is the Ngarrindjeri concept of Yannarumi—broadly translated as ‘Speaking as Country’. Resulting interaction then reinforces Ngarrindjeri nationhood and agency in protecting Ngarrindjeri lands and waters, by sharing in knowledge production that respects rights to cultural knowledge as a form of intellectual property. Through this method of relationship-building, including in the domain of scientific research conducted on Ngarrindjeri Ruwe (Country), the NRA has been able to take an active and progressive role in the development of environmental policy and in decision-making around water and natural resource management (NRM) in the Murray-Darling Basin regio

    Measuring Information Transfer

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    An information theoretic measure is derived that quantifies the statistical coherence between systems evolving in time. The standard time delayed mutual information fails to distinguish information that is actually exchanged from shared information due to common history and input signals. In our new approach, these influences are excluded by appropriate conditioning of transition probabilities. The resulting transfer entropy is able to distinguish driving and responding elements and to detect asymmetry in the coupling of subsystems.Comment: 4 pages, 4 Figures, Revte

    Webteaching: sequencing of subject matter in relation to prior knowledge of pupils

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    Two experiments are discussed in which the sequencing procedure of webteaching is compared with a linear sequence for the presentation of text material.\ud \ud In the first experiment variations in the level of prior knowledge of pupils were studied for their influence on the sequencing mode of text presentation. Prior knowledge greatly reduced the effect of the size of sequencing procedures.\ud \ud In the second experiment pupils with a low level of prior knowledge studied a text, following either a websequence or a linear sequence. Webteaching was superior to linear teaching on a number of dependent variables. It is concluded that webteaching is an effective sequencing procedure in those cases where substantial new learning is required

    Variations in strain affect friction and microstructure evolution in copper under a reciprocating tribological load

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    The microstructure of the materials constituting a metallic frictional contact strongly influences tribological performance. Being able to tailor friction and wear is challenging due to the complex microstructure evolution associated with tribological loading. Here, we investigate the effect of the strain distribution on these processes. High-purity copper plates were morphologically surface textured with two parallel rectangles—referred to as membranes—over the entire sample length by micro-milling. By keeping the width of these membranes constant and only varying their height, reciprocating tribological loading against sapphire discs resulted in different elastic and plastic strains. Finite element simulations were carried out to evaluate the strain distribution in the membranes. It was found that the maximum elastic strain increases with decreasing membrane stiffness. The coefficient of friction decreases with increasing membrane aspect ratio. By analyzing the microstructure and local crystallographic orientation, we found that both show less change with decreasing membrane stiffness

    Test your surrogate data before you test for nonlinearity

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    The schemes for the generation of surrogate data in order to test the null hypothesis of linear stochastic process undergoing nonlinear static transform are investigated as to their consistency in representing the null hypothesis. In particular, we pinpoint some important caveats of the prominent algorithm of amplitude adjusted Fourier transform surrogates (AAFT) and compare it to the iterated AAFT (IAAFT), which is more consistent in representing the null hypothesis. It turns out that in many applications with real data the inferences of nonlinearity after marginal rejection of the null hypothesis were premature and have to be re-investigated taken into account the inaccuracies in the AAFT algorithm, mainly concerning the mismatching of the linear correlations. In order to deal with such inaccuracies we propose the use of linear together with nonlinear polynomials as discriminating statistics. The application of this setup to some well-known real data sets cautions against the use of the AAFT algorithm.Comment: 14 pages, 15 figures, submitted to Physical Review

    The interplay of intrinsic and extrinsic bounded noises in genetic networks

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    After being considered as a nuisance to be filtered out, it became recently clear that biochemical noise plays a complex role, often fully functional, for a genetic network. The influence of intrinsic and extrinsic noises on genetic networks has intensively been investigated in last ten years, though contributions on the co-presence of both are sparse. Extrinsic noise is usually modeled as an unbounded white or colored gaussian stochastic process, even though realistic stochastic perturbations are clearly bounded. In this paper we consider Gillespie-like stochastic models of nonlinear networks, i.e. the intrinsic noise, where the model jump rates are affected by colored bounded extrinsic noises synthesized by a suitable biochemical state-dependent Langevin system. These systems are described by a master equation, and a simulation algorithm to analyze them is derived. This new modeling paradigm should enlarge the class of systems amenable at modeling. We investigated the influence of both amplitude and autocorrelation time of a extrinsic Sine-Wiener noise on: (i)(i) the Michaelis-Menten approximation of noisy enzymatic reactions, which we show to be applicable also in co-presence of both intrinsic and extrinsic noise, (ii)(ii) a model of enzymatic futile cycle and (iii)(iii) a genetic toggle switch. In (ii)(ii) and (iii)(iii) we show that the presence of a bounded extrinsic noise induces qualitative modifications in the probability densities of the involved chemicals, where new modes emerge, thus suggesting the possibile functional role of bounded noises

    Effect of promoter architecture on the cell-to-cell variability in gene expression

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    According to recent experimental evidence, the architecture of a promoter, defined as the number, strength and regulatory role of the operators that control the promoter, plays a major role in determining the level of cell-to-cell variability in gene expression. These quantitative experiments call for a corresponding modeling effort that addresses the question of how changes in promoter architecture affect noise in gene expression in a systematic rather than case-by-case fashion. In this article, we make such a systematic investigation, based on a simple microscopic model of gene regulation that incorporates stochastic effects. In particular, we show how operator strength and operator multiplicity affect this variability. We examine different modes of transcription factor binding to complex promoters (cooperative, independent, simultaneous) and how each of these affects the level of variability in transcription product from cell-to-cell. We propose that direct comparison between in vivo single-cell experiments and theoretical predictions for the moments of the probability distribution of mRNA number per cell can discriminate between different kinetic models of gene regulation.Comment: 35 pages, 6 figures, Submitte

    Statistical Theory of Spin Relaxation and Diffusion in Solids

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    A comprehensive theoretical description is given for the spin relaxation and diffusion in solids. The formulation is made in a general statistical-mechanical way. The method of the nonequilibrium statistical operator (NSO) developed by D. N. Zubarev is employed to analyze a relaxation dynamics of a spin subsystem. Perturbation of this subsystem in solids may produce a nonequilibrium state which is then relaxed to an equilibrium state due to the interaction between the particles or with a thermal bath (lattice). The generalized kinetic equations were derived previously for a system weakly coupled to a thermal bath to elucidate the nature of transport and relaxation processes. In this paper, these results are used to describe the relaxation and diffusion of nuclear spins in solids. The aim is to formulate a successive and coherent microscopic description of the nuclear magnetic relaxation and diffusion in solids. The nuclear spin-lattice relaxation is considered and the Gorter relation is derived. As an example, a theory of spin diffusion of the nuclear magnetic moment in dilute alloys (like Cu-Mn) is developed. It is shown that due to the dipolar interaction between host nuclear spins and impurity spins, a nonuniform distribution in the host nuclear spin system will occur and consequently the macroscopic relaxation time will be strongly determined by the spin diffusion. The explicit expressions for the relaxation time in certain physically relevant cases are given.Comment: 41 pages, 119 Refs. Corrected typos, added reference

    Surface softening in metal-ceramic sliding contacts: An experimental and numerical investigation

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    This study investigates the tribolayer properties at the interface of ceramic/metal (i.e., WC/W) sliding contacts using various experimental approaches and classical atomistic simulations. Experimentally, nanoindentation and micropillar compression tests, as well as adhesion mapping by means of atomic force microscopy, are used to evaluate the strength of tungsten?carbon tribolayers. To capture the influence of environmental conditions, a detailed chemical and structural analysis is performed on the worn surfaces by means of XPS mapping and depth profiling along with transmission electron microscopy of the debris particles. Experimentally, the results indicate a decrease in hardness and modulus of the worn surface compared to the unworn one. Atomistic simulations of nanoindentation on deformed and undeformed specimens are used to probe the strength of the WC tribolayer and despite the fact that the simulations do not include oxygen, the simulations correlate well with the experiments on deformed and undeformed surfaces, where the difference in behavior is attributed to the bonding and structural differences of amorphous and crystalline W-C. Adhesion mapping indicates a decrease in surface adhesion, which based on chemical analysis is attributed to surface passivation
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