10,744 research outputs found

    Markets - Water Markets: Australia’s Murray-Darling Basin and the US Southwest

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    Worldwide supplies of fresh water are increasingly scarce relative to demand. This problem is likely to be exacerbated with climate change. In this paper, we examine water markets in both Australia’s Murray Darling Basin and the western US and their prospects for addressing water scarcity. The two regions share a number of important similarities including: climate variability that requires investment in reservoirs to make water available in low-rainfall periods; the need for internal and cross-border (state) water management; an historical major allocation of water to irrigators; increasing competition among different uses (agricultural, environmental and recreational in situ uses, urban demand); and the potential for water trading to more smoothly and quickly allocate water across these competing uses. A comparison of the two regions provides important insights about how economic factors can encourage more efficient water allocation, market structure and government regulation.

    An Integrated Assessment of Water Markets: Australia, Chile, China, South Africa and the USA

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    The paper provides an integrated framework to assess water markets in terms of their institutional underpinnings and the three ‘pillars’ of integrated water resource management: economic efficiency, equity and environmental sustainability. This framework can be used: (1) to benchmark different water markets; (2) to track performance over time; and (3) to identify ways in which water markets might be adjusted by informed policy makers to achieve desired goals. The framework is used to identify strengths and limitations of water markets in: (1) Australia’s Murray-Darling Basin; (2) Chile (in particular the Limarí Valley); (3) China (in particular, the North); (4) South Africa; and (5) the western United States. It identifies what water markets are currently able to contribute to integrated water resource management, what criteria underpin these markets, and which components of their performance may require further development.

    Water Scarcity and Water Markets: A Comparison of Institutions and Practices in the Murray-Darling Basin of Australia and the Western US

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    Water markets in Australia’s Murray-Darling Basin (MDB) and the US west are compared in terms of their ability to allocate scarce water resources among competing uses. Both locations have been in the forefront of the development of water markets with defined water rights and conveyance structures to assist in the reallocation of water across competing demands. They also share the challenge of managing water with climate variability and climate change. As these two markets occur in developed, wealthy countries, their experiences in water markets with different water rights (appropriative, riparian and statutory rights) provide ‘best-case’ scenarios of what institutional arrangements work best, indicate which are less effective, and demonstrate what might be possible for greater use of water markets elsewhere in the world. The paper finds that the gains from trade in the MDB is worth hundreds of millions of dollars in per year, total turnover in water rights exceeds 2billionperyearandthevolumeoftradeaccountsforover202 billion per year and the volume of trade accounts for over 20% of surface water extractions by irrigators. In the key states of Arizona, California, Colorado, Nevada, and Texas, trades of committed water annually range between 5% and 15% of total state freshwater diversions with over 4.3 billion (2008 $) spent or committed by urban buyers between 1987 and 2008. Despite the clear benefits of water markets in both locations, there are on-going restrictions to trade that limit the potential gains and also third-party effects from use that require resolution.

    Near-field interaction between domain walls in adjacent Permalloy nanowires

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    The magnetostatic interaction between two oppositely charged transverse domain walls (DWs)in adjacent Permalloy nanowires is experimentally demonstrated. The dependence of the pinning strength on wire separation is investigated for distances between 13 and 125 nm, and depinning fields up to 93 Oe are measured. The results can be described fully by considering the interaction between the full complex distribution of magnetic charge within rigid, isolated DWs. This suggests the DW internal structure is not appreciably disturbed by the pinning potential, and that they remain rigid although the pinning strength is significant. This work demonstrates the possibility of non-contact DW trapping without DW perturbation and full continuous flexibility of the pinning potential type and strength. The consequence of the interaction on DW based data storage schemes is evaluated.Comment: 4 pages, 4 figures, 1 page supplimentary material (supporting.ps

    Habitat requirements and conservation needs of peripheral populations : the case of the great crested newt (Triturus cristatus) in the Scottish Highlands

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    Edge populations are of conservation importance because of their roles as reservoirs of evolutionary potential and in understanding a given species’ ecological needs. Mainly due to loss of aquatic breeding sites, the great crested newt Triturus cristatus is amongst the fastest declining amphibian species in Europe. Focusing on the north-westerly limit of the T. cristatus range, in the Scottish Highlands, we aimed to characterise habitat requirements and conservation needs of an isolated set of edge populations. We recorded 129 breeding-pond related environmental parameters, and used a variable-selection procedure followed by random forest analysis to build a predictive model for the species’ present occurrence, as well as for population persistence incorporating data on population losses. The most important variables predicting T. cristatus occurrence and persistence were associated with pond quality, pond shore and surrounding terrestrial habitat (especially mixed Pinus sylvestris - Betula woodland), and differed from those identified in the species’ core range. We propose that habitat management and pond creation should focus on the locally most favourable habitat characteristics to improve the conservation status and resilience of populations. This collaborative work, between conservation agencies and scientific researchers, is presented as an illustrative example of linking research, management and conservation

    Diagnostic ultrasound should be performed without upper intensity limits

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135131/1/mp5500.pd

    Optimal search strategies for hidden targets

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    What is the fastest way of finding a randomly hidden target? This question of general relevance is of vital importance for foraging animals. Experimental observations reveal that the search behaviour of foragers is generally intermittent: active search phases randomly alternate with phases of fast ballistic motion. In this letter, we study the efficiency of this type of two states search strategies, by calculating analytically the mean first passage time at the target. We model the perception mecanism involved in the active search phase by a diffusive process. In this framework, we show that the search strategy is optimal when the average duration of "motion phases" varies like the power either 3/5 or 2/3 of the average duration of "search phases", depending on the regime. This scaling accounts for experimental data over a wide range of species, which suggests that the kinetics of search trajectories is a determining factor optimized by foragers and that the perception activity is adequately described by a diffusion process.Comment: 4 pages, 5 figures. to appear in Phys. Rev. Let

    Changing social contracts in climate-change adaptation

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    Risks from extreme weather events are mediated through state, civil society and individual action 1 , 2 . We propose evolving social contracts as a primary mechanism by which adaptation to climate change proceeds. We use a natural experiment of policy and social contexts of the UK and Ireland affected by the same meteorological event and resultant flooding in November 2009. We analyse data from policy documents and from household surveys of 356 residents in western Ireland and northwest England. We find significant differences between perceptions of individual responsibility for protection across the jurisdictions and between perceptions of future risk from populations directly affected by flooding events. These explain differences in stated willingness to take individual adaptive actions when state support retrenches. We therefore show that expectations for state protection are critical in mediating impacts and promoting longer-term adaptation. We argue that making social contracts explicit may smooth pathways to effective and legitimate adaptation

    Finite energy/action solutions of p1p_1 Yang-Mills equations on p2p_2 Schwarzschild and deSitter backgrounds for dimension d4d \ge 4

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    Physically relevant gauge and gravitational theories can be seen as special members of hierarchies of more elaborate systems. The Yang-Mills (YM) system is the first member of a hierarchy of Lagrangians which we will index by p1p_1, and the Einstein-Hilbert (EH) system of general relativity is the first member of another hierarchy which we index by p2p_2. In this paper, we study the classical equations of the p1=1,2p_1 = 1,2 YM hierarchy considered in the background of special geometries (Schwarzschild, deSitter,anti-deSitter) of the p2=1,2,3p_2=1,2,3 EH hierarchy. Solutions are obtained in various dimensions and lead to several examples of non-self-dual YM fields. When p1=p2p_1=p_2 self-dual solutions exist in addition. Their action is equal to the Chern-Pontryagin charge and can be compared with that of the non-self-dual solutions.Comment: LaTeX, 25 pages, 2 figures, new title, minor change

    Testing the standard fireball model of GRBs using late X-ray afterglows measured by Swift

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    We show that all X-ray decay curves of GRBs measured by Swift can be fitted using one or two components both of which have exactly the same functional form comprised of an early falling exponential phase followed by a power law decay. The 1st component contains the prompt gamma-ray emission and the initial X-ray decay. The 2nd component appears later, has a much longer duration and is present for ~80% of GRBs. It most likely arises from the external shock which eventually develops into the X-ray afterglow. In the remaining ~20% of GRBs the initial X-ray decay of the 1st component fades more slowly than the 2nd and dominates at late times to form an afterglow but it is not clear what the origin of this emission is. The temporal decay parameters and gamma/X-ray spectral indices derived for 107 GRBs are compared to the expectations of the standard fireball model including a search for possible "jet breaks". For ~50% of GRBs the observed afterglow is in accord with the model but for the rest the temporal and spectral indices do not conform to the expected closure relations and are suggestive of continued, late, energy injection. We identify a few possible jet breaks but there are many examples where such breaks are predicted but are absent. The time, T_a, at which the exponential phase of the 2nd component changes to a final powerlaw decay afterglow is correlated with the peak of the gamma-ray spectrum, E_peak. This is analogous to the Ghirlanda relation, indicating that this time is in some way related to optically observed break times measured for pre-Swift bursts.Comment: submitted to Ap
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