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- Campana, Pietro Elia, et al.
(författare)
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Managing agricultural drought in Sweden using a novel spatially-explicit model from the perspective of water-food-energy nexus
- 2018
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Ingår i: Journal of Cleaner Production. - : Elsevier. - 0959-6526 .- 1879-1786. ; 197, s. 1382-1393
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Tidskriftsartikel (refereegranskat)abstract
- Using a multi-disciplinary approach, this paper integrated spatial analysis with agricultural and energy system modelling to assess the impacts of drought on crop water demand, water availability, crop yield, and electricity requirements for irrigation. This was done by a novel spatially-explicit and integrated water-food-energy nexus model, using the spatial climatic data generated by the mesoscale MESAN and STRANG models. In this study, the model was applied to quantify the effects of drought on the Swedish irrigation sector in 2013, a typical drought year, for a specific crop. The results show that drought can severely affect the crop yield if irrigation is not applied, with a peak yield reduction of 18 t/ha, about 50 % loss as compared to the potential yield in irrigated conditions. Accordingly, the water and energy requirements for irrigation to halt the negative drought effects and maintain high yields are significant, with the peaks up to 350 mm and 700 kWh per hectare. The developed model can be used to provide near real-time guidelines for a comprehensive drought management system. The model also has significant potentials for applications in precision agriculture, especially using high-resolution satellite data.
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- Dubiel, T W, et al.
(författare)
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Mitral valve prosthetic implantation with preservation of native mitral valve apparatus
- 1994
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Ingår i: Scandinavian journal of thoracic and cardiovascular surgery. - 0036-5580. ; 28:3-4, s. 115-121
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Tidskriftsartikel (refereegranskat)abstract
- To avoid postoperative morbidity and mortality often associated with left ventricular dysfunction after mitral valve replacement (MVR) for chronic mitral insufficiency, reconstruction or preservation of the native mitral valve apparatus may be attempted during mitral prosthetic implantation (MPI). The effects of mitral surgery on heart function, studied with echocardiography and radionuclide angiography, were compared in seven patients with MPI (study group) and five with MVR (control group) who underwent complete preoperative, early postoperative and 3-6 months follow-up examinations. Preoperatively there was significant intergroup difference only in right ventricular ejection fraction measured at radionuclide angiography, which was lower in the MPI group (p < 0.05). At follow-up the MPI group had improved as regards this fraction (p < 0.005) and stroke volume index (p < 0.05). The number of patients with improved NYHA class at follow-up was significantly greater in the MPI group. Our preliminary experience with preservation of the native mitral valve apparatus thus suggests that the method offers haemodynamic advantages for postoperative right ventricular function.
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- Hellgren, Laila, et al.
(författare)
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Optimal timing of aortic valve replacement for aortic stenosis : are we operating late?
- 2003
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Ingår i: Scandinavian Cardiovascular Journal. - : Informa UK Limited. - 1401-7431 .- 1651-2006. ; 37:5, s. 266-269
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To evaluate the adherence to current guidelines for surgery in patients with aortic valve stenosis.DESIGN: From 1 January 1997 to 31 May 1999, 99 patients were accepted for aortic valve surgery with preserved left ventricular function and normal coronary angiogram. On admission for operation, 20 patients were evaluated regarding symptoms, exercise capacity, and left ventricular morphology and function.RESULTS: There were 14 men and 6 women, mean age 64.3 years. Years from symptom onset varied from 2.1 to 3.2. Dyspnoea was the most common limiting symptom. Thirty per cent of the patients were classified as NYHA IIIB. Physical capacity was reduced to 79% of the expected. Left ventricular hypertrophy was present in 14/20 patients. Left ventricular systolic function was reduced with mean ejection fraction of 0.46. Diastolic dysfunction (E/A ratio <1) was present in 12 patients.CONCLUSION: Many patients accepted for aortic valve replacement due to aortic stenosis show advanced disease and are referred for surgery later in the disease process than is recommended in the current guidelines.
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- Koehler, Birgit, 1980-, et al.
(författare)
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Sunlight-induced carbon dioxide emissions from inland waters
- 2014
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Ingår i: Global Biogeochemical Cycles. - 0886-6236 .- 1944-9224. ; 28:7, s. 696-711
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Tidskriftsartikel (refereegranskat)abstract
- The emissions of carbon dioxide (CO2) from inland waters are substantial on a global scale. Yet, the fundamental question remains open which proportion of these CO2 emissions is induced by sunlight via photochemical mineralization of dissolved organic carbon (DOC), rather than by microbial respiration during DOC decomposition. Also, it is unknown on larger spatial and temporal scales how photochemical mineralization compares to other C fluxes in the inland water C cycle. We combined field and laboratory data with atmospheric radiative transfer modeling to parameterize a photochemical rate model for each day of the year 2009, for 1086 lakes situated between latitudes from 55 to 69°N in Sweden. The sunlight-induced production of dissolved inorganic carbon (DIC) averaged 3.8 ± 0.04 g C m-2 yr-1, which is a flux comparable in size to the organic carbon burial in the lake sediments. Countrywide, 151 ± 1 kt C yr-1 was produced by photochemical mineralization, corresponding to about 12% of total annual mean CO2 emissions from Swedish lakes. With a median depth of 3.2 m, the lakes were generally deep enough that incoming, photochemically active photons were absorbed in the water column. This resulted in a linear positive relationship between DIC photoproduction and the incoming photon flux, which correspond to the absorbed photons. Therefore, the slope of the regression line represents the wavelength- and depth-integrated apparent quantum yield of DIC photoproduction. We used this relationship to obtain a first estimate of DIC photoproduction in lakes and reservoirs worldwide. Global DIC photoproduction amounted to 13 and 35 Mt C yr-1 under overcast and clear sky, respectively. Consequently, these directly sunlight-induced CO2 emissions contribute up to about one tenth to the global CO2 emissions from lakes and reservoirs, corroborating that microbial respiration contributes a substantially larger share than formerly thought, and generate annual C fluxes similar in magnitude to the C burial in natural lake sediments worldwide.
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