243 research outputs found

    Towards Design For a Nutrient Trading Programme to Improve Water Quality in Lake Rotorua

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    This paper explores how to enhance the role for academic research (natural sciences, economics and their integration; and stakeholder management) within the development and implementation of water quality policy in New Zealand. Our focus is on the use of market based instruments and particularly nutrient trading programmes, which are one important part of the potential tool kit to address these issues. We discuss why nutrient trading might be an appropriate instrument for the Lake Rotorua catchment. We survey the existing literature and then outline the outstanding scientific, economic and governance questions that need to be addressed to design an effective trading programme. Finally we discuss how to design a process to address these questions drawing on both technical and practical knowledge through a learning process.water quality, emissions trading, non-point source pollution, nutrients, Rotorua, communication, learning, Resource /Energy Economics and Policy, Q53, Q57, Q58, A12,

    Towards Design for a Nutrient Trading Programme to Improve Water Quality in Lake Rotorua

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    This paper explores how to enhance the role for academic research (natural sciences, economics and their integration; and stakeholder management) within the development and implementation of water quality policy in New Zealand. Our focus is on the use of market based instruments and particularly nutrient trading programmes, which are one important part of the potential tool kit to address these issues. We discuss why nutrient trading might be an appropriate instrument for the Lake Rotorua catchment. We survey the existing literature and then outline the outstanding scientific, economic and governance questions that need to be addressed to design an effective trading programme. Finally we discuss how to design a process to address these questions drawing on both technical and practical knowledge through a learning process.water quality; emissions trading; non-point source pollution; nutrients; Rotorua; communication; learning

    Reforming natural resource policies in Developing Countries : politics and forests in the Philippines, Thailand and Costa Rica, 1980-1996

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    Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Political Science, 1998.Includes bibliographical references (p. 295-317).by David M. Fairman.Ph.D

    The utility of convection-permitting ensembles for the prediction of stationary convective bands

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    This study examines convection-permitting numerical simulations of four cases of terrain-locked quasi-stationary convective bands over the UK. For each case, a 2.2-km grid-length 12-member ensemble and 1.5-km grid-length deterministic forecast are analyzed, each with two different initialization times. Object-based verification is applied to determine whether the simulations capture the structure, location, timing, intensity and duration of the observed precipitation. These verification diagnostics reveal that the forecast skill varies greatly between the four cases. Although the deterministic and ensemble simulations captured some aspects of the precipitation correctly in each case, they never simultaneously captured all of them satisfactorily. In general, the models predicted banded precipitation accumulations at approximately the correct time and location, but the precipitating structures were more cellular and less persistent than the coherent quasi-stationary bands that were observed. Ensemble simulations from the two different initialization times were not significantly different, which suggests a potential benefit of time-lagging subsequent ensembles to increase ensemble size. The predictive skill of the upstream larger-scale flow conditions and the simulated precipitation on the convection-permitting grids were strongly correlated, which suggests that more accurate forecasts from the parent ensemble should improve the performance of the convection-permitting ensemble nested within it

    Limb interventions in patients undergoing treatment with an unsupported bifurcated aortic endograft system: A review of the Phase II EVT Trial

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    AbstractIntroduction: Both supported and unsupported bifurcated endograft limbs develop flow-restricting lesions, including kinks, stenoses, and occlusions, which can be identified during or after surgery. Recognition and intervention are essential to achieve long-term graft patency and a satisfactory functional result. This report represents a comprehensive retrospective review of graft limb interventions from the Phase II EVT Trial with the Endovascular Grafting System unsupported bifurcated endograft (Guidant/EVT, Menlo Park, Calif). Methods: The study population consists of 242 patients who underwent treatment with bifurcated endografts implanted during the EVT Phase II Trial. Graft limb interventions have been divided into two groups: those in whom the intervention occurred during surgery versus those in whom the intervention occurred after surgery. Parameters studied included type, incidence, and timing of graft limb intervention, indications for intervention, procedures performed, and overall patient outcome. Results: The mean follow-up period was 31 months. Primary, primary assisted, and secondary limb patency rates were 61.6%, 93.7%, and 97.1%, respectively. Technical success rate at case completion was 97.5%. In 68 of the 242 cases, limb interventions were performed during surgery to assure patency (28.1%). In 28 cases, interventions were performed after surgery (11.6%). Of these postoperative limb problems, 82% occurred during the first 6 months. Repeat limb interventions were necessitated in three patients (1.2%). Within the intraoperative intervention group, perceived indications included kinks (15%), stenosis (57%), dissection (6%), graft redundancy (12%), and instances of twists, thrombosis, and pressure gradients (10%). These findings were successfully managed with percutaneous transluminal angioplasty only (41%), percutaneous transluminal angioplasty and stent (50%), and various combined interventions. Within the postoperative intervention group, symptomatic indications included stenosis (46%) and thrombosis/occlusion (54%). These postoperative limb events were successfully managed with stent (64%), thrombolysis (32%), and femoral-femoral bypass (21%). When limb dysfunction developed in the postoperative setting, it most often occurred within the first 6 months of implantation. Only one patient in this Phase II cohort had a lower extremity amputation unrelated to a graft limb abnormality. Conclusion: The unsupported bifurcated limbs of this endograft necessitated primary adjunctive intervention in 40% of cases. Primary intervention was two times more likely to be performed at the time of the implant rather than after surgery. Repeat limb interventions were not common. Endograft limb flow problems were successfully treated with standard endovascular or surgical interventions or both. These data may support prophylactic stenting of unsupported Ancure graft limbs. A strategy that includes both intraoperative and early postoperative graft limb surveillance is essential to detect reduced limb flow. (J Vasc Surg 2002;36:118-26.
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