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Search Results: 1 - 10 of 418617 matches for " Alexander J. B. Zehnder "
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The Three Pillars of Sustainability Framework: Approaches for Laws and Governance  [PDF]
William Henry Clune, Alexander J. B. Zehnder
Journal of Environmental Protection (JEP) , 2018, DOI: 10.4236/jep.2018.93015
Abstract: The three pillars of sustainability framework is a multidisciplinary implementation and solutions oriented approach that recognizes most successful and scalable sustainability solutions require the presence of, and are driven by, all three pillars simultaneously: 1) technology and innovation; 2) laws and governance; and 3) economics and financial incentives. The three pillars framework is strategic because it often reveals or describes specific and feasible changes that advance sustainability solutions within markets and institutional settings. The section on technology discusses the crucial role that technology plays in creating new ways for doing more in our rapidly urbanizing communities by using less resources and energy inputs. The section on economics discusses problems with current conceptions of economic welfare that measure growth (flow) rather than the asset base (wealth), and explores possibilities for integrated and multidisciplinary analysis for coupled economic and social systems. The section on laws and governance considers the role of legal frameworks related to incentives, regulatory baselines, and in public policy formation, including influences and feedback effects from social norms, changing culture, and sustainability education. Technological development and engaging economic markets are at the center of our best and most rapidly deployable sustainability solutions. In that context, a specific focus is given throughout the discussion sections to the key role of laws and governance in supporting relevant, effective, and sustainable technological and economic development, as well as to highlight the crucial (often final) steps the law plays in successfully implementing new sustainability projects. As the discussions and examples (taken from Asia, the US, and Europe) demonstrate, the three pillars framework is flexible and useful in a number of contexts, as a solutions template, as an integrated planning approach, as a decision making guide, and for determining project priorities.
A Global and Spatially Explicit Assessment of Climate Change Impacts on Crop Production and Consumptive Water Use
Junguo Liu, Christian Folberth, Hong Yang, Johan R?ckstr?m, Karim Abbaspour, Alexander J. B. Zehnder
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0057750
Abstract: Food security and water scarcity have become two major concerns for future human's sustainable development, particularly in the context of climate change. Here we present a comprehensive assessment of climate change impacts on the production and water use of major cereal crops on a global scale with a spatial resolution of 30 arc-minutes for the 2030s (short term) and the 2090s (long term), respectively. Our findings show that impact uncertainties are higher on larger spatial scales (e.g., global and continental) but lower on smaller spatial scales (e.g., national and grid cell). Such patterns allow decision makers and investors to take adaptive measures without being puzzled by a highly uncertain future at the global level. Short-term gains in crop production from climate change are projected for many regions, particularly in African countries, but the gains will mostly vanish and turn to losses in the long run. Irrigation dependence in crop production is projected to increase in general. However, several water poor regions will rely less heavily on irrigation, conducive to alleviating regional water scarcity. The heterogeneity of spatial patterns and the non-linearity of temporal changes of the impacts call for site-specific adaptive measures with perspectives of reducing short- and long-term risks of future food and water security.
Water availability, demand and reliability of in situ water harvesting in smallholder rain-fed agriculture in the Thukela River Basin, South Africa
J. C. M. Andersson, A. J. B. Zehnder, G. P. W. Jewitt,H. Yang
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2009,
Abstract: Water productivity in smallholder rain-fed agriculture is of key interest for improved food and livelihood security. A frequently advocated approach to enhance water productivity is to adopt water harvesting and conservation technologies (WH). This study estimates water availability for potential in situ WH, and supplemental water demand (SWD) in smallholder agriculture in South Africa's Thukela River Basin (29 000 km2, mean annual precipitation 550–2000 mm yr 1). The study includes process dynamics governing runoff generation and crop water demands, quantification of prediction uncertainty, and an analysis of the reliability of in situ WH. The agro-hydrological model SWAT (Soil and Water Assessment Tool) was calibrated and evaluated with the Sequential Uncertainty Fitting algorithm against observed discharge (at ten stations) and maize yield (the dominant crop type) for the period 1997–2006. The water availability was based on the generated surface runoff in smallholder areas. The SWD was derived from a scenario where crop water deficits were met from an unlimited external water source. The reliability was calculated as the percentage of years in which water availability ≥SWD. This reflects the risks of failure induced by the temporal variability in the water availability and the SWD. The calibration reduced the predictive uncertainty and resulted in a satisfactory model performance. For smallholder maize yield, the Root Mean Squared Error was 0.02 t ha 1 during both the calibration and the evaluation periods. The width of the uncertainty band was reduced by 23% due to the calibration. For discharge during the calibration (evaluation) period, the ten-station range in the weighted coefficient of determination (Φ) was 0.16–0.85 (0.18–0.73), and in the coefficient of determination (R2) 0.42–0.83 (0.28–0.72). The calibration reduced the width of the uncertainty band by 25% on average. The results show that the smallholder crop water productivity is currently low in the basin (spatiotemporal median: 0.08–0.22 kg m 3, 95% prediction uncertainty band (95PPU)). Water is available for in situ WH (spatiotemporal median: 0–17 mm year 1, 95PPU) which may aid in enhancing the crop water productivity by meeting some of the SWD (spatiotemporal median: 0–113 mm year 1, 95PPU). However, the reliability of in situ WH is highly location specific and overall rather low. Of the 1850 km2 of smallholder lands, 20–28% display a reliability ≥25%, 13–16% a reliability ≥50%, and 4–5% a reliability ≥75% (95PPU). This suggests that the risk of failure of in situ WH is relatively high in many areas of the basin.
Analyses of impacts of China's international trade on its water resources and uses
Z. Y. Zhang, H. Yang, M. J. Shi, A. J. B. Zehnder,K. C. Abbaspour
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2011,
Abstract: This study provides an insight into the impact of China's international trade of goods and services on its water resources and uses. Virtual water flows associated with China's international trade are quantified in an input-output framework. The analysis is scaled down to the sectoral and provincial levels to trace the origins and destinations of virtual water flows associated with the international trade. The results show that China is a net virtual water exporter of 4.8 × 1010 m3 yr 1, accounting for 2.1% of its renewable water resources and 8.6% of the total water use. Water scarce regions tend to have higher percentages of virtual water export relative to their water resources and water uses. In the water scarce Huang-Huai-Hai region, the net virtual water export accounts for 8.0% of the region's water resources and 11.3% of its water uses. For individual sectors, major net virtual water exporters are those where agriculture provides raw materials in the initial process of the production chain. The results suggest that China's economic gains from being a world "manufacture factory" have come at a high cost to its water resources.
Analyses of impacts of China's international trade on its water resources and uses
Z. Y. Zhang,H. Yang,M. J. Shi,A. J. B. Zehnder
Hydrology and Earth System Sciences Discussions , 2011, DOI: 10.5194/hessd-8-3543-2011
Abstract: This study provides an insight into the impact of China's international trade of goods and services on its water resources and uses. Virtual water flows associated with China's international trade are quantified in an input-output framework. The analysis is scaled down to the sectoral and provincial levels to trace the origins and destinations of virtual water flows associated with the international trade. The results reveal that China is a net virtual water exporter of 4.7 × 1010 m3 year 1, accounting for 2.1% of its total water resources and 8.9% of the total water use. Water scarce regions tend to have higher percentages of virtual water export relative to their water resources and water uses. In the water scarce Huang-Huai-Hai region, the net virtual water export accounts for 7.9% of the region's water resources and 11.2% of its water uses. For individual sectors, major net virtual water exporters are those where agriculture provides raw materials in the initial process of the production chain and/or pollution intensity is high. The results suggest that China's economic gains from being a world "manufacture factory" have come at a high cost to its water resources and through pollution to its environment.
Water availability, water demand, and reliability of in situ water harvesting in smallholder rain-fed agriculture in the Thukela River Basin, South Africa
J. C. M. Andersson,A. J. B. Zehnder,G. P. W. Jewitt,H. Yang
Hydrology and Earth System Sciences Discussions , 2009,
Abstract: Water productivity in smallholder rain-fed agriculture is of key interest for food and livelihood security. A frequently advocated approach to enhance water productivity is to adopt water harvesting and conservation technologies (WH). This study estimates water availability for in situ WH and supplemental water demands (SWD) in smallholder agriculture in the Thukela River Basin, South Africa. It incorporates process dynamics governing runoff generation and crop water demands, an explicit account of the reliability of in situ WH, and uncertainty considerations. The agro-hydrological model SWAT (Soil and Water Assessment Tool) was calibrated and evaluated with the SUFI-2 algorithm against observed crop yield and discharge in the basin. The water availability was based on the generated surface runoff in smallholder areas. The SWD was derived from a scenario where crop water deficits were met from an unlimited external water source. The reliability was calculated as the percentage of years in which the water availability ≥ the SWD. It reflects the risks of failure induced by the temporal variability in these factors. The results show that the smallholder crop water productivity is low in the basin (spatiotemporal median: 0.08–0.22 kg m 3, 95% prediction uncertainty band (95PPU). Water is available for in situ WH (spatiotemporal median: 0–17 mm year 1, 95PPU) which may aid in enhancing the crop water productivity by meeting some of the SWD (spatiotemporal median: 0–113 mm year 1, 95PPU). However, the reliability of in situ WH is highly location specific and overall rather low. Of the 1850 km2 of smallholder lands, 20–28% display a reliability ≥25%, 13–16% a reliability ≥50%, and 4–5% a reliability ≥75% (95PPU). This suggests that the risk of failure of in situ WH is relatively high in many areas of the basin.
Virtual water trade: an assessment of water use efficiency in the international food trade
H. Yang, L. Wang, K. C. Abbaspour,A. J. B. Zehnder
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2006,
Abstract: Amid an increasing water scarcity in many parts of the world, virtual water trade as both a policy instrument and practical means to balance the local, national and global water budget has received much attention in recent years. Building upon the knowledge of virtual water accounting in the literature, this study assesses the efficiency of water use embodied in the international food trade from the perspectives of exporting and importing countries and at the global and country levels. The investigation reveals that the virtual water flows primarily from countries of high crop water productivity to countries of low crop water productivity, generating a global saving in water use. Meanwhile, the total virtual water trade is dominated by green virtual water, which constitutes a low opportunity cost of water use as opposed to blue virtual water. A sensitivity analysis, however, suggests high uncertainties in the virtual water accounting and the estimation of the scale of water saving. The study also raises awareness of the limited effect of water scarcity on the global virtual water trade and the negative implications of the global water saving for the water use efficiency and food security in importing countries and the environment in exporting countries. The analysis shows the complexity in evaluating the efficiency gains in the international virtual water trade. The findings of the study, nevertheless, call for a greater emphasis on rainfed agriculture to improve the global food security and environmental sustainability.
Virtual water highway: water use efficiency in global food trade
H. Yang,L. Wang,K. C. Abbaspour,A. J. B. Zehnder
Hydrology and Earth System Sciences Discussions , 2006,
Abstract: Amid an increasing water scarcity in many parts of the world, virtual water trade as both a policy instrument and practical means to balance the regional, national and global water budget has received much attention in recent years. Built upon the knowledge of virtual water accounting in the literature, this study examines the efficiency of the resource use embodied in the global virtual water trade from the perspectives of exporting and importing countries. Different characteristics between "green" and "blue" virtual water corresponding to rainfed and irrigated agriculture are elaborated. The investigation reveals that the virtual water flows primarily from countries of high water productivity to countries of low water productivity, generating a global saving of water resources. Meanwhile, the domination of green virtual water in the total virtual water trade constitutes low opportunity costs and environmental impacts as opposed to blue virtual water. The results suggest efficiency gains in the global food trade in terms of water resource utilization. The study raises awareness of negative impacts of increasing reliance on irrigation for food production in many countries, including food exporting countries. The findings of the study call for a greater emphasis on rainfed agriculture to improve global food security and environmental sustainability.
Nebular Abundance Errors
J. Alexander,B. Balick
Physics , 1997, DOI: 10.1086/118505
Abstract: The errors inherent to the use of the standard "ionization correction factor" ("i_CF") method of calculating nebular conditions and relative abundances of H, He, N, O, Ne, S, and Ar in emission line nebulae have been investigated under conditions typical for planetary nebulae. The photoionization code CLOUDY was used to construct a series of model nebulae with properties spanning the range typical of PNe. Its radial "profiles" of bright, frequently observed optical emission lines were then summed over a variety of "apertures" to generate sets of emission line measurements. These resulting line ratios were processed using the i_CF method to "derive" nebular conditions and abundances. We find that for lines which are summed over the entire nebula the i_CF-derived abundances differ from the input abundances by less than 5% for He and O up to 25% or more for Ne, S, and Ar. For resolved observations, however, the discrepancies are often much larger and are systematically variable with radius. This effect is especially pronounced in low-ionization zones where nitrogen and oxygen are neutral or once-ionized such as in FLIERs, ansae and ionization fronts. We argue that the reports of stellar-enriched N in the FLIERs of several PNe are probably specious.
Scintigraphic imaging of focal hypoxic tissue: development and clinical applications of 123I-IAZA
Wiebe, Leonard I.;McEwan, Alexander J. B.;
Brazilian Archives of Biology and Technology , 2002, DOI: 10.1590/S1516-89132002000500010
Abstract: affected tissues in a number of diseases, including cancer, stroke, cardiac infarction and diabetes, develop focal tissue hypoxia during their progression. the presence of hypoxic tissue may make the disease refractory to therapy, as in the case of solid tumor therapy using low let ionizing radiation. in other pathologies, the detection of viable but hypoxic tissues may serve as a prodromal indicator of developing disease (e.g. diabetes),or as a prognostic indicator for management of the disease (e.g. stroke). over the past two decades, a number of hypoxia radioimaging agents have been developed and tested clinically. of these, 18f-fmiso and 123i-iaza are the most widely used radiotracers for pet and spect/planar imaging, respectively. iaza and fmiso are a 2-nitroimidazoles that chemically bind to subcellular components of viable hypoxic tissues. they sensitize hypoxic tumour to the killing effects of ionizing radiation via mechanisms that mimic the radiosensitizing effects of oxygen, and are therefore called oxygen mimetics. the oxygen mimetic effect is attributable in large part to the covalent binding of reductively-activated nitroimidazole intermediates to critical cellular macromolecules. nitroimidazoles labelled with gamma-emitting radionuclides (e.g. 18f-fmiso and 123i-iaza) have been used as scintigraphic markers of tumour hypoxia, based on the need to identify radioresistant hypoxic tumour cells as part of the radiotherapy planning process. broader interest in non-invasive, imaging-based identification of focal hypoxia in a number of diseases has extended hypoxia studies to include peripheral vascular disease associated with diabetes, rheumatoid arthritis, stroke, myocardial ischaemia, brain trauma and oxidative stress. in this review, the current status of hypoxia-selective studies with 123i-iaza , an experimental diagnostic radiopharmaceutical, is reviewed with respect to its pre-clinical development and clinical applications.
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