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- Brodersen, Jakob, et al.
(författare)
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Short-and long term niche segregation and individual specialization of brown trout (Salmo trutta) in species poor Faroese lakes
- 2012
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Ingår i: Environmental Biology of Fishes. - : Springer Science and Business Media LLC. - 0378-1909 .- 1573-5133. ; 93:3, s. 305-318
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Tidskriftsartikel (refereegranskat)abstract
- Trophic niche divergence is considered to be a major process by which species coexistence is facilitated. When studying niche segregation in lake ecosystems, we tend to view the niche on a one-dimensional pelagic-littoral axis. In reality, however, the niche use may be more complex and individual fidelity to a niche may be variable both between and within populations. In order to study this complexity, relative simple systems with few species are needed. In this paper, we study how competitor presence affects the resource use of brown trout (Salmo trutta) in 11 species-poor Faroese lakes by comparing relative abundance, stable isotope ratios and diet in multiple habitats. In the presence of three-spined sticklebacks (Gasterosteus aculeatus), a higher proportion of the trout population was found in the pelagic habitat, and trout in general relied on a more pelagic diet base as compared to trout living in allopatry or in sympatry with Arctic charr (Salvelinus alpinus). Diet analyses revealed, however, that niche-segregation may be more complex than described on a one-dimensional pelagic-littoral axis. Trout from both littoral and offshore benthic habitats had in the presence of sticklebacks a less benthic diet as compared to trout living in allopatry or in sympatry with charr. Furthermore, we found individual habitat specialization between littoral/benthic and pelagic trout in deep lakes. Hence, our findings indicate that for trout populations interspecific competition can drive shifts in both habitat and niche use, but at the same time they illustrate the complexity of the ecological niche in freshwater ecosystems.
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- Bernstad, Anna, et al.
(författare)
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Need for improvements in physical pretreatment of source-separated household food waste.
- 2013
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Ingår i: Waste Management: international journal of integrated waste management, science and technology. - : Elsevier BV. - 1879-2456. ; 33:3, s. 746-754
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the present study was to investigate the efficiency in physical pretreatment processes of source-separated solid organic household waste. The investigation of seventeen Swedish full-scale pretreatment facilities, currently receiving separately collected food waste from household for subsequent anaerobic digestion, shows that problems with the quality of produced biomass and high maintenance costs are common. Four full-scale physical pretreatment plants, three using screwpress technology and one using dispergation technology, were compared in relation to resource efficiency, losses of nitrogen and potential methane production from biodegradable matter as well as the ratio of unwanted materials in produced biomass intended for wet anaerobic digestion. Refuse generated in the processes represent 13-39% of TS in incoming wet waste. The methane yield from these fractions corresponds to 14-36Nm(3)/ton separately collected solid organic household waste. Also, 13-32% of N-tot in incoming food waste is found in refuse. Losses of both biodegradable material and nutrients were larger in the three facilities using screwpress technology compared to the facility using dispersion technology.(1) Thus, there are large potentials for increase of both the methane yield and nutrient recovery from separately collected solid organic household waste through increased efficiency in facilities for physical pretreatment. Improved pretreatment processes could thereby increase the overall environmental benefits from anaerobic digestion as a treatment alternative for solid organic household waste.
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- Herrera, I., et al.
(författare)
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Analysis for the integration of solar energy to sugarcane bagasse cogeneration power plant in the Cuban context : A case study
- 2019
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Ingår i: ECOS 2019 - Proceedings of the 32nd International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems. - : Institute of Thermal Technology. - 9788361506515 ; , s. 3597-3605
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Konferensbidrag (refereegranskat)abstract
- Cuba is a small island located in the Caribbean Sea, with an extension of 109,886 km2 and a population of about 11,000,000 of which 98.2% have access to electric energy services. The national electric network has a power capacity of 7,741 MW, but only 4.3% is generated from Renewable Energy Sources (RES). In this context a new policy for the development of RES has been launched by the government, in order to increase its share in the energy matrix and decrease energy cost. A special contribution is expected from sugarcane bagasse cogeneration power plants. The installed capacity in this sector is 470 MW, it is expected to rise up to 872 MW from 2018 to 2030, generating electricity at a cost lower than 0.15 USD/kWh. To this purpose, 25 facilities will be upgraded to bioelectric plants with an expected annual generation of 4,300 GWh, avoiding 3.65 MMtonCO2/year. For modernizing the energy scheme of sugar cane enterprises many technical possibilities exist, for example: increase working pressure, increase working temperature, use the maximum amount of residue as fuel, etc. Economic aspects should be considered, in order to achieve low energy costs in a sustainable way. One of the problem related to the power generation in the sugar industry is the seasonality, as the facilities must stop once the harvesting period ends due to the lack of fuel (bagasse). However, if some solar energy could be added to the process some bagasse could be stored and used to run the power plants off season and hence improve their economic performance. In this work the integration of solar energy to a small sugarcane bagasse cogeneration power plant was studied. The cane crushing capacity is 2,300 TCD (Tonnes of Cane/Day) and the crushing season is from December to April. Every season 60,400 tons of bagasse are available. The process steam pressure is 2.5 bar(abs). A parabolic solar field for heating the boiler feed water was studied. With a field of 34,500 m2, the facility could run for two month off season, with an internal return rate of 6% and a payback period of 10 years. Additional studies are needed to improve the economic indicators.
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- Myléus, Anna, MD PhD, et al.
(författare)
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Questionnaire showed that Swedish paediatric clinics complied well with the revised European guidelines for diagnosing coeliac disease
- 2019
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Ingår i: Acta Paediatrica. - : John Wiley & Sons. - 0803-5253 .- 1651-2227. ; 108:6, s. 1140-1143
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Tidskriftsartikel (refereegranskat)abstract
- Aim: In 2012, revised criteria for diagnosing childhood coeliac disease were published by the European Society for Paediatric Gastroenterology, Hepatology and Nutrition and incorporated into the revised Swedish guidelines the same year. These made it possible, in certain cases, to diagnose coeliac disease without taking small bowel biopsies. This survey assessed the extent to which the new guidelines were implemented by Swedish paediatric clinics two years after their introduction.Methods: In October 2014, we distributed a paper questionnaire including five questions on diagnostic routines to the 40 paediatric clinics in university or regional hospitals in Sweden that perform small bowel biopsies.Results: All 36 (90%) clinics that responded used anti-tissue transglutaminase antibodies as the initial diagnostic test and some also used serological markers. Most clinics (81%) used endoscopy and took multiple duodenal biopsies, whereas only a few (19%) occasionally employed a suction capsule. Almost all clinics (86%) omitted taking small bowel biopsies in symptomatic children with repeatedly high coeliac serology and positive genotyping, thereby avoiding the need for invasive endoscopy under anaesthesia.Conclusion: The 2012 Swedish Paediatric Coeliac Disease Diagnostic Guidelines had been widely accepted and implemented in routine health care two years after their introduction.
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- Nieminen, Katri, et al.
(författare)
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Nulliparous pregnant womens narratives of imminent childbirth before and after internet-based cognitive behavioural therapy for severe fear of childbirth: a qualitative study
- 2015
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Ingår i: British Journal of Obstetrics and Gynecology. - : Wiley: 12 months. - 1470-0328 .- 1471-0528. ; 122:9, s. 1259-1265
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Tidskriftsartikel (refereegranskat)abstract
- ObjectiveTo describe the expectations concerning imminent childbirth before and after 8weeks of internet-based cognitive behavioural therapy (ICBT) among nulliparous pregnant women with severe fear of childbirth. DesignQualitative study of nulliparous pregnant womens narratives before and after CBT. SettingThe first ICBT programme for treating severe fear of childbirth. SampleFifteen nulliparous pregnant Swedish women with severe fear of childbirth participating in an ICBT self-help programme. MethodsSemi-structured open-ended questions over the internet before and after 8weeks of ICBT. The data were analysed using thematic analysis. Main outcome measuresThe participants narratives pertaining to five different situations during labour and delivery before and after ICBT. ResultsAfter therapy, participants described a more realistic attitude towards imminent childbirth, more self-confidence and more active coping strategies. They perceived their partners and the staff as more supportive. They were more aware of the approaching meeting with their baby when giving birth. ConclusionsFollowing the ICBT programme, participants changed their attitude towards imminent childbirth from negative to more positive. This was manifested in positive and more realistic expectations regarding themselves, their partner and the staff that would look after them.
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- Ruiz-Puerta, Emily J., et al.
(författare)
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Holocene deglaciation drove rapid genetic diversification of Atlantic walrus
- 2023
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Ingår i: Proceedings of the Royal Society B: Biological Sciences. - 1471-2954. ; 290:2007, s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- Rapid global warming is severely impacting Arctic ecosystems and is predicted to transform the abundance, distribution and genetic diversity of Arctic species, though these linkages are poorly understood. We address this gap in knowledge using palaeogenomics to examine how earlier periods of global warming influenced the genetic diversity of Atlantic walrus (Odobenus rosmarus rosmarus), a species closely associated with sea ice and shallow-water habitats. We analysed 82 ancient and historical Atlantic walrus mitochondrial genomes (mitogenomes), including now-extinct populations in Iceland and the Canadian Maritimes, to reconstruct the Atlantic walrus’ response to Arctic deglaciation. Our results demonstrate that the phylogeography and genetic diversity of Atlantic walrus populations was initially shaped by the Last Glacial Maximum (LGM), surviving in distinct glacial refugia, and subsequently expanding rapidly in multiple migration waves during the late Pleistocene and early Holocene. The timing of diversification and establishment of distinct populations corresponds closely with the chronology of the glacial retreat, pointing to a strong link between walrus phylogeography and sea ice. Our results indicate that accelerated ice loss in the modern Arctic may trigger further dispersal events, likely increasing the connectivity of northern stocks while isolating more southerly stocks putatively caught in small pockets of suitable habitat.
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- Wegener, Moritz, et al.
(författare)
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How much does it cost to go off-grid with renewables? : A case study of a polygeneration system for a neighbourhood in hermosillo, Mexico
- 2020
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Ingår i: 11th International Conference on Sustainability and Energy in Buildings, SEB 2019. - Singapore : Springer. ; , s. 395-405
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Konferensbidrag (refereegranskat)abstract
- As governments and companies struggle to meet their own objectives for the energy transition, more innovative social and technological measures are needed to reduce Greenhouse Gas (GHG) emissions. For this purpose, an assessment of an off-grid polygeneration system, which can serve the electric and cooling demand of a neighbourhood in Hermosillo, Mexico, has been conducted. Energy computations have been done, the energy demand of one dwelling has been measured to ascertain the correctness of the computations, and a demand model for the entire neighbourhood has been created. Based on the model, an off-grid polygeneration system has been designed, which uses a biodiesel engine, PV panels, and an absorption chiller. The system has been optimized for its economic performance and is compared to the currently used system. The results show that the polygeneration system with higher energy efficiency could reduce GHG emissions down to 14%. However, electricity in Hermosillo is heavily subsidized making it harder for innovative systems to compete. Moreover, even without the state subsidies to the end user, the polygeneration system has still a nearly 30% higher Net Present Cost (NPC) than the conventional system over its project lifetime of 20 years. Nonetheless, with precise political incentives and further advances in the applied technologies, small-scale renewable polygeneration systems could become cost-efficient alternatives in the near future.
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