18,562 research outputs found

    Predicing Ecological Effects of Watershed-Wide Rain Garden Implementation Using a Low-Cost Methodology

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    Stormwater control measures (SCMs) have been employed to mitigate peak flows and pollutants ssociated with watershed urbanization. Downstream ecological effects caused by the implementation of SCMs are largely unknown, especially at the watershed scale. Knowledge of these effects could help with setting goals for and targeting locations of local restoration efforts. Unfortunately, studies such as these typically require a high level of time and effort for the investigating party, of which resources are often limited. This study proposes a low-cost investigation method for the prediction of ecological effects on the watershed scale with the implementation of rain garden systems by using publicly available data and software. For demonstration purposes, a typical urban watershed was modeled using Storm Water Management Model (SWMM) 5.0. Forty-five models were developed in which the percent impervious area was varied 3 to 80%, and the fraction of rain gardens implemented with respect to the number of structures was varied from to 100%. The river chub fish (Nocomis micropogon) and its congeners (Nocomis spp.) were chosen as ecological indicators, as they are considered to be keystone species through interspecific nesting association. Depth and velocity criteria for successful nest building locations of the river chub were determined; these criteria can then be applied to many other watersheds. In this study, both base flow conditions and a typical summer storm event (1.3 cm, 6 h duration) were evaluated. During the simulated storm, nest-building locations were not affected in the 3 and 5% impervious cover models. Nest destruction was found to occur in approximately 54% of the original nest building sites for the 9% and 10% impervious areas. Nearly all of the nest-building locations were uninhabitable for impervious areas 20% and greater. Rain garden implementation significantly improved river chub habitat in the simulation, with greatest marginal benefit at lower levels of implementation

    Searching for Keynes: An Essay on the Political Economy of Fiscal Policy, with Application to Canada, 1870-2000 - revised version

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    Keynes' General Theory (1936) is arguably one of the most important books of the twentieth century. His ideas for stabilizing the aggregate economy have profoundly influenced economic theory as well as popular opinion about what governments can and should do with respect to the business cycle. On the other hand, whether Keynesian theory has substantially altered the course of public policy remains an open question. In this paper we identify the elements required for any investigation of the impact of Keynes' ideas on policy choices and then conduct our own 'search for Keynes', applying an intertemporal spatial voting framework to study the fiscal history of the Government of Canada from 1870 to 2000. The long time series allows the construction of a counterfactual – one of several essential elements - showing what governments would have planned to do ‘after Keynes’, if Keynes' ideas had not in fact been present. Our results suggest that textbook Keynesianism is identifiable in the Canadian data.Keynesianism, spatial voting, permanent versus transitory policy, political equilibrium, liquidity constraints

    On Intrinsic Magnetic Moments In Black Hole Candidates

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    In previous work we found that many of the spectral properties of low mass x-ray binaries, including galactic black hole candidates could be explained by a magnetic propeller model that requires an intrinsically magnetized central object. Here we describe how the Einstein field equations of General Relativity and equipartition magnetic fields permit the existence of highly red shifted, extremely long lived, collapsing, radiating objects. We examine the properties of these collapsed objects and discuss characteristics that might lead to their confirmation as the source of black hole candidate phenomena.Comment: 4 pages, emulateapj, accepted for ApJ Letters, October 20, 200
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