436 research outputs found

    Transient transmission oscillations in doped and undoped lithium niobate induced by near-infrared femtosecond pulses

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    Transient transmission oscillations in X-cut and Z-cut congruent, iron-doped, and magnesium-doped lithium niobate samples were measured using 50 fs, 800 nm, 0.5 nJ pulses from a self-mode-locked Ti:sapphire laser in an optical pump–probe system. Several Raman-active oscillation modes excited by these pulses were observed as changes in the transmitted probe intensity versus time delay between the pump and probe pulses. The samples were rotated to determine how the incident polarization of the pump pulses affects the mode excitations. The observed Raman-active oscillations correspond to previously reported symmetry modes measured with traditional, continuous-wave, Raman spectroscopy using the same scattering geometry. In addition, a polariton mode and other, previously unreported, lower-frequency modes were observed in each of the samples. The transmission intensity data for each sample were fit successfully to a superposition of sinusoidal functions with exponentially decaying amplitudes

    Reconfiguring an Irrigation Landscape to Improve Provision of Ecosystem Services

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    Over-allocation of fresh water resources to consumptive uses, coupled with recurring drought and the prospect of climate change, is compromising the stocks of natural capital in the world’s basins and reducing their ability to provide ecosystem services. To combat this, governments world wide are making significant investment in efforts to improve sharing of water between consumptive uses and the environment, with many investments centred on modernisation of inefficient irrigation delivery systems, and the purchase of water by government for environmental flows. In this study, spatial targeting was applied within a cost-benefit framework to reconfigure agricultural land use in an irrigation district to achieve a 20% reduction in agricultural water use to increase environmental flows and improve the provision of other ecosystem services. We demonstrate using spatial planning and optimisation models that a targeted land use reconfiguration policy approach could potentially increase the net present value of ecosystem services by up to AUS463.7m.Thisprovidesathresholdlevelofinvestmentthatwouldbejustifiedonthebasisofbenefitsthattheinvestmentproduces.Theincreaseinecosystemservicesincluderecovering61GLofwaterforenvironmentalflows,thesequestrationof10.6mtonnesofCO2−e/yr,a13EC(?S/cm)reductioninriversalinity,andanoverall24463.7m. This provides a threshold level of investment that would be justified on the basis of benefits that the investment produces. The increase in ecosystem services include recovering 61 GL of water for environmental flows, the sequestration of 10.6m tonnes of CO2-e/yr, a 13 EC (?S/cm) reduction in river salinity, and an overall 24% increase in the value of agriculture. Without a targeted approach to planning, a 20% reduction in water for irrigation could result in the loss of AUS68.7m in economic returns to agriculture which may be only marginally offset by the increased value of ecosystem services resulting from the return of 61 GL of water to the environment.landscape planning, geographic information systems, cost-benefit analysis, irrigation, climate change, water management, spatial targeting, environmental valuation

    Rethinking irrigation modernisation: Realising multiple objectives through the integration of fisheries

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    Irrigation has been, and will remain, instrumental in addressing water security (Sustainable Development Goal (SDG) 6), food insecurity (SDG 2) and poverty (SDG 1) goals. However, the global context in which irrigation takes place is changing rapidly. A call for healthier and more sustainable food systems is placing new demands on how irrigation is developed and managed. Growing pressures from competing water uses in the domestic and industrial sectors, as well increasing environmental awareness, mean irrigation is increasingly called on to perform better, delivering acceptable returns on investment and simultaneously improving food security, rural livelihoods and nutrition, as well as supporting environmental conservation. Better integration of fisheries (including aquaculture) in irrigation planning, investment and management can contribute to the modernisation of irrigation and the achievement of the multiple objectives that it is called on to deliver. A framework illustrating how fisheries can be better integrated with irrigation, and how the two can complement each other across a range of scales, from scheme to catchment and, ultimately, national level, is presented

    Market-based instruments for the governance of coastal and marine ecosystem services: An analysis based on the Chinese case

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    Scholars and policy makers have increasingly emphasized the role of market-based instruments (MBIs) for the governance of ecosystem services (ESs). Limited focus however exists on a systematic understanding of how coastal and marine governance facilitates MBIs to sustain ESs. This paper develops a framework for analyzing the governance of MBIs on the basis of four distinctive aspects, including price, regulatory support, coordination, and spatial consideration. This framework can be used to analyze how MBIs are reflected in the governance of coastal and marine ESs and to understand to what extent a market environment is created for ESs. This study focuses on one in-depth case, namely Chinese national coastal and marine governance. The case suggests that existing MBIs are based on ES valuation and impacts and serve for understanding transactions. Moreover, the MBIs tend to show a clear focus on improving policy coordination. Finally, a further understanding of MBIs for coastal and marine governance is needed to also explore the role of voluntary choice

    How coastal strategic planning reflects interrelationships between ecosystem services: a four-step method

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    Explicit and integrated inclusion of ecosystem services (ESs) and their interrelationships can improve the quality of strategic plans and decision-making processes. However, there is little systematic analysis of how ES interrelationships are framed in policy language, particularly in coastal planning discourse. The objective of this paper is therefore to present a four-step method, based on content analysis, to assess ES interrelationships in coastal strategic planning documents. The method consists of: 1) selecting strategic plans; 2) identifying ESs; 3) identifying drivers, ESs and their effects; and 4) constructing relational diagrams. The four-step method is applied to a case of Jiaozhou Bay in China, demonstrating its capacity of identifying which drivers and ES trade-offs and synergies are formulated in coastal strategic plans. The method is helpful to identify overlooked ES interrelationships, inform temporal and spatial issues, and assess the continuity of plans' attention to interrelationships. The main methodological contributions are discussed by emphasizing its broad scope of drivers and ESs and an explicit distinction among the cause of relationships. The developed method also has the potential of cross-fertilizing other kinds of approaches and facilitating practical planning processes

    Variation in the Structure of Bird Nests between Northern Manitoba and Southeastern Ontario

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    Traits that converge in appearance under similar environmental conditions among phylogenetically independent lineages are thought to represent adaptations to local environments. We tested for convergence in nest morphology and composition of birds breeding in two ecologically different locations in Canada: Churchill in northern Manitoba and Elgin in southeastern Ontario. We examined nests from four families of passerine birds (Turdidae: Turdus, Parulidae: Dendroica, Emberizidae: Passerculus and Fringillidae: Carduelis) where closely related populations or species breed in both locations. Nests of American Robins, Yellow Warblers, and Carduelis finches had heavier nest masses, and tended to have thicker nest-walls, in northern Manitoba compared with conspecifics or congenerics breeding in southeastern Ontario. Together, all species showed evidence for wider internal and external nest-cup diameters in northern Manitoba, while individual species showed varying patterns for internal nest-cup and external nest depths. American Robins, Yellow Warblers, and Carduelis finches in northern Manitoba achieved heavier nest masses in different ways. American Robins increased all materials in similar proportions, and Yellow Warblers and Common Redpolls used greater amounts of select materials. While changes in nest composition vary uniquely for each species, the pattern of larger nests in northern Manitoba compared to southeastern Ontario in three of our four phylogenetically-independent comparisons suggests that birds are adapting to similar selective pressures between locations
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