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ObjectivesTo compare the Lecompte technique and the spiral anastomosis (complete anatomic correction) two decades after arterial switch operation (ASO).MethodsNine patients after primary ASO with Lecompte and 6 selected patients after spiral anastomosis were evaluated 20.8 ± 2.1 years after ASO versus matched controls. Blood flow dynamics and flow profiles (e.g. vorticity, helicity) in the great arteries were quantified from time-resolved 3D magnetic resonance imaging (MRI) phase contrast flow measurements (4D flow MR) in addition to a comprehensive anatomical and functional cardiovascular MRI analysis.ResultsCompared with spiral reconstruction, patients with Lecompte showed more vortex formation, supranatural helical blood flow (relative helicity in aorta: 0.036 vs 0.089; P < 0.01), a reduced indexed cross-sectional area of the left pulmonary artery (155 vs 85 mm²/m²; P < 0.001) and more semilunar valve dysfunctions (n = 5 vs 1). There was no difference in elastic aortic wall properties, ventricular function, myocardial perfusion and myocardial fibrosis between the two groups. Cross-sectional area of the aortic sinus was larger in patients than in controls (669 vs 411 mm²/m²; P < 0.01). In the spiral group, the pulmonary root was rotated after ASO more towards the normal left position (P < 0.01).ConclusionsIn this study, selected patients with spiral anastomoses showed, two decades after ASO, better physiologically adapted blood flow dynamics, and attained a closer to normal anatomical position of their great arteries, as well as less valve dysfunction. Considering the limitations related to the small number of patients and the novel MRI imaging techniques, these data may provoke reconsidering the optimal surgical approaches to transposition of the great arteries repair.

Byline: Tatiana Ermolieva (1), Yuri Ermoliev (1), Gunther Fischer (1), Matthias Jonas (1), Marek Makowski (1), Fabian Wagner (1) Abstract: The idea of market-based carbon emission trading and carbon taxes is gaining in popularity as a global climate change policy instrument. However, these mechanisms might not necessarily have a positive outcome unless their value reflects socioeconomic and environmental impacts and regulations. Moreover, the fact that they have various inherent exogenous and endogenous uncertainties raises serious concerns about their ability to reduce emissions in a cost-effective way. This paper aims to introduce a simple stochastic model that allows the robustness of economic mechanisms for emission reduction under multiple natural and human-related uncertainties to be analyzed. Unlike standard equilibrium state analysis, the model shows that the explicit introduction of uncertainties regarding emissions, abatement costs, and equilibrium states makes it almost impossible for existing market-based trading and carbon taxes to be environmentally safe and cost-effective. Here we propose a computerized multi-agent trading model. This can be viewed as a prototype to simulate an emission trading market that is regulated in a decentralized way. We argue that a market of this type is better equipped to deal with long-term emission reductions, their direct regulation, irreversibility, and 'lock-in' equilibria. Author Affiliation: (1) International Institute for Applied Systems Analysis, Schlossplatz 1, 2361, Laxenburg, Austria Article History: Registration Date: 22/06/2010 Received Date: 05/01/2009 Accepted Date: 15/06/2010 Online Date: 16/07/2010

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.techfore.2006.05.027 Byline: Francesco N. Tubiello (a)(b), Gunther Fischer (a) Keywords: Agriculture; Climate impacts; Mitigation; World food supply Abstract: What are the implications for agriculture of mitigating greenhouse gas emissions? By when and by how much are impacts reduced? Where does it matter most? We investigated these questions within the new A2 emission scenario, recently developed at the International Institute of Applied Systems Analysis with revised population and gross domestic product projections. Coupling an agro-ecological model to a global food trade model, two distinct sets of climate simulations were analyzed: 1) A non-mitigated scenario, with atmospheric CO.sub.2 concentrations over 800 ppm by 2100; and 2) A mitigation scenario, with CO.sub.2 concentrations stabilized at 550 ppm by 2100. Impacts of climate change on crop yield were evaluated for the period 1990-2080, then used as input for economic analyses. Key trends were computed over the 21st century for food demand, production and trade, focusing on potential monetary (aggregate value added) and human (risk of hunger) impacts. The results from this study suggested that mitigation could positively impact agriculture. With mitigation, global costs of climate change, though relatively small in absolute amounts, were reduced by 75-100%; and the number of additional people at risk of malnutrition was reduced by 80-95%. Significant geographic and temporal differences were found. Regional effects often diverged from global net results, with some regions worse off under mitigation compared to the unmitigated case. Author Affiliation: (a) Land-Use Change and Agriculture Program at the International Institute for Applied Systems Analysis (IIASA), Laxenburg, Austria (b) Goddard Institute for Space Studies, Columbia University, New York, NY, USA Article History: Received 7 February 2006; Revised 12 April 2006; Accepted 24 May 2006

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.techfore.2006.05.021 Byline: Gunther Fischer (a), Francesco N. Tubiello (a)(b), Harrij van Velthuizen (a), David A. Wiberg (a) Keywords: Water; Agriculture; Irrigation; Climate change; Mitigation Abstract: Potential changes in global and regional agricultural water demand for irrigation were investigated within a new socio-economic scenario, A2r, developed at the International Institute for Applied Systems Analysis (IIASA) with and without climate change, with and without mitigation of greenhouse gas emissions. Water deficits of crops were developed with the Food and Agriculture Organization (FAO)-IIASA Agro-ecological Zone model, based on daily water balances at 0.5[degrees] latitudex0.5[degrees] longitude and then aggregated to regions and the globe. Future regional and global irrigation water requirements were computed as a function of both projected irrigated land and climate change and simulations were performed from 1990 to 2080. Future trends for extents of irrigated land, irrigation water use, and withdrawals were computed, with specific attention given to the implications of climate change mitigation. Renewable water-resource availability was estimated under current and future climate conditions. Results suggest that mitigation of climate change may have significant positive effects compared with unmitigated climate change. Specifically, mitigation reduced the impacts of climate change on agricultural water requirements by about 40%, or 125-160billionm.sup.3 (Gm.sup.3) compared with unmitigated climate. Simple estimates of future changes in irrigation efficiency and water costs suggest that by 2080 mitigation may translate into annual cost reductions of about 10billion US$. Author Affiliation: (a) Land-Use Change and Agriculture Program at the International Institute for Applied Systems Analysis (IIASA), Laxenburg, Austria (b) Goddard Institute for Space Studies, Columbia University, New York, NY, USA Article History: Received 7 February 2006; Revised 10 May 2006; Accepted 24 May 2006