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- Åstrand, Elaine, et al.
(författare)
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Comparison of Classifiers for Decoding Sensory and Cognitive Information from Prefrontal Neuronal Populations.
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:1, s. 1-14
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Tidskriftsartikel (refereegranskat)abstract
- Decoding neuronal information is important in neuroscience, both as a basic means to understand how neuronal activity is related to cerebral function and as a processing stage in driving neuroprosthetic effectors. Here, we compare the readout performance of six commonly usedclassifiers at decoding two different variables encoded by the spiking activity of the non-human primate frontal eye fields (FEF): the spatial position of a visual cue, and the instructed orientation of the animal's attention. While the first variable is exogenously driven by the environment, the second variable corresponds to the interpretation of the instruction conveyed by the cue; it is endogenously driven and corresponds to the output of internalcognitive operations performed on the visual attributes of the cue. These two variables were decoded using either a regularized optimal linear estimator in its explicit formulation, an optimal linear artificial neural network estimator, a non-linear artificial neural network estimator, a non-linear naïve Bayesian estimator, a non-linear Reservoir recurrent network classifier or a non-linear Support Vector Machine classifier. Our results suggest that endogenous information such as the orientation of attention can be decoded from the FEF with the same accuracy as exogenous visualinformation. All classifiers did not behave equally in the face of population size and heterogeneity, the available training and testing trials, the subject's behavior and the temporal structure of the variable of interest. In most situations, the regularized optimal linear estimator and the non-linear Support Vector Machine classifiers outperformed the other tested decoders.
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| 3. |
- Ekblom, Örjan
(författare)
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Physical fitness and overweight in Swedish youths
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aim of the present thesis was to describe the level of physical fitness and prevalence of overweight and obesity in Swedish youths, and their trends over 14 years. Additionally, the relation between fitness and overweight on the one hand and physical activity on the other was examined. In 2001, a total of 2118 children, aged 10, 13 and 16 years, were invited from 48 randomly selected schools in Sweden. Out of these, 1732 or 81.8 % participated in the testing. For trend analyses, data collected in 1987 from a sample of 516 children were used. When subjects in the 2001 sample were analysed according to proposed cut-off values, 15.7% (95% CI: 14.1% to 17.6%) of all subjects were found to be overweight and 4.3% (95% CI: 3.4% to 5.4%) were obese. The total prevalence accordingly being 20.1% (95% CI: 18.3% to 22.0%). This sample proved to be heterogeneous concerning overweight status. When obesity and overweight were combined the highest prevalence (26.6%, 95% CI: 21.2 to 32.7) was found in 10-year-old girls and the lowest (17.5%, 95% CI: 13.6 to 22.2) in 16-year-old girls. The prevalence in 2001 was nearly 2.5 times higher, compared to the 1987-sample. Girls attending schools in smaller towns or on the countryside had a nearly two-fold prevalence of overweight and obesity, compared to girls living in the major cities. The difference was less pronounced in boys. The prevalence of overweight and obesity was related to level of physical activity in 10 and 13 years old children but not in 16 years old. Results from the performance tests in the 1987 and 2001 samples were compared. Concerning cardio-respiratory performance, girls aged 16 years showed only small differences, whereas boys in the 2001 sample performed worse compared to boys in the 1987-sample (46 ml x kg-1 x min-1 vs. 41 ml x kg-1 x min-1 for 1987 and 2001, respectively, and median difference 9.2 %, 95% CI: -16.7 to -2.2). Concerning neuro-muscular performance, the comparisons of results between the 1987 and 2001 samples showed varying results. Generally, performance on the upper body and trunk muscles strength and endurance tests was lower in 2001 compared to 1987. Neuromuscular performance in the lower body differed less. For both boys and girls, differences in neuro-muscular performance between subjects in different activity strata increased with age. Results showed only small differences in neuro-muscular performance between active and less active strata at age 10, but larger at age 13 and 16 years in both boys and girls. And at age 13 and 16 years, neuro-muscular performance differed widely between active and less active girls. At age 10, only small differences were found in cardio-respiratory performance between active and less active subjects (both girls and boys). At age 13 and 16 years both girls and boys showed large differences in cardio-respiratory performance between activity levels, with better performance in more active children.
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| 7. |
- Nydahl, Helena, et al.
(författare)
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Building Refurbishment from a Life Cycle Perspective - An Environmental Return on Investment Approach
- 2018
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Ingår i: Cold Climate HVAC 2018. - Cham : Springer. - 9783030006617 - 9783030006624 ; , s. 253-263
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Konferensbidrag (refereegranskat)abstract
- This study applies an environmental return on investment approach to evaluate building refurbishment from a life cycle perspective. The used methodology focuses on the changes introduced by refurbishment, i.e. added embodied environmental impact and changed operational environmental impact, from a life cycle perspective with the technical service life of the refurbishment measure as a time limit. The methodology is applied to a case study in Umeå, located 455 km south of the Arctic Circle, with a unique set of data on reduction in operational energy. The result show the environmental impact, energy (Joule) and GWP (CO2-eq), in terms of environmental return on investment of the case study refurbishment measures. The case study shows that the methodology is a useable approach to compare refurbishment measures from a life cycle perspective. It is possible to use the methodology as a tool at an early stage in planning of sustainable building refurbishment from a life cycle perspective. For a widespread use of a tool based on an environmental return on investment approach, further research on guidelines for sustainable environmental return on investment values is required.
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| 8. |
- Nydahl, Helena, 1990-
(författare)
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Communication of life cycle assessment results : life cycle key performance indicators
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The global warming that we are on track for will result in a severe loss of natural capital leading to significant losses in economic capital when urban infrastructure is destroyed, agricultural productivity declines and poverty spread among other disasters. Climate change due to emissions does not only affect the polluter, the hazardous effects becomes evident on a global level. An essential tool to enable decision‑making with concern to the welfare of the global commons is life cycle assessment (LCA). LCA compile and evaluate the inputs, outputs, and potential environmental impacts of a product system throughout its life cycle. The reviewed literature frames a gap regarding interpretation of LCA-results and inquire for guidelines that address a wide range of stakeholders to enable informed decision-making with regard to the welfare of the global commons. Some studies even argue that an apparent weakness of LCA-result communication is the understanding of what the results mean for the economic key performance indicators (KPIs) of the stakeholder. Thus, this thesis aims to contribute to the development of guidelines for interpretation of LCA-results by introducing an approach for communicating LCA-results that is compatible with the economically driven nature of stakeholders. The specific research questions (RQ) of this thesis are: (RQ1) How can well-established economic KPIs be utilised to quantify environmental impact? and (RQ2) How does incorporation of monetary valuation of environmental impacts and related environmental aspects affect the LCA-result and communication of results?These research questions have led to life cycle key performance indicators (LC‑KPIs) that quantify life cycle economic and environmental impacts in a way that take after the traditional economic KPIs of the stakeholders, which is outlined as essential to improve the understanding of LCA-results. The LC‑KPIs utilize the traditional economic KPIs of return on investment (ROI) and annual yield (AY). Additionally, to manage the large amount of non-commensurate units of holistic life cycle sustainability assessment, monetary valuation has been applied. Hence, contributing to the research area of monetary valuation in LCA by introducing and testing new approaches.The introduced LC-KPIs have been specified for building LCA and exemplified by applying them to a number of Swedish case buildings. The result show that the climate-economic assessment of building refurbishment differs compared to the traditional economic assessment when monetary valuation is utilized in LCA with the LC-KPI of ROIEconomy+. However, in the comparative assessment of building refurbishment and new construction, the LCA‑result does not change compared to the traditional economic assessment when monetary valuation is utilized in LCA with the LC-KPI of ELCCA. This is explained by the high costs associated with the investment and energy use of buildings and may not be the case if products with lower investment and energy use costs and high life cycle greenhouse-gas emissions would be studied. Still, if a purely environmental assessment of a product is wished for, the LC-KPI should only include monetary valuation of environmental impact factors and exclude traditional economic performance. Thus, the case study result defines further scope for research on the subject of monetary valuation in LCA and inquire for a wider spectrum of LC-KPIs that utilizes monetary valuation.The introduced approach of this thesis contribute to the development of guidelines for interpretation of LCA-results. Nevertheless, there are still challenges that needs to be addressed in the development of robust LCA-result interpretation. Still, the LC‑KPIs used in this thesis address the “cognitive logics” of a wide range of stakeholders and provide an approach for communication of LCA-results which improve the understanding of LCA-results.
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| 9. |
- Nydahl, Helena, 1990-, et al.
(författare)
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Environmental Performance Measures to Assess Building Refurbishment from a Life Cycle Perspective
- 2019
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Ingår i: Energies. - : MDPI. - 1996-1073. ; 12:2
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Tidskriftsartikel (refereegranskat)abstract
- Energy efficiency investments in existing buildings are an effective way of reducing the environmental impact of the building stock. Even though policies in the European Union and elsewhere promote a unilateral focus on operational energy reduction, scientific studies highlight the importance of applying a life cycle perspective to energy refurbishment. However, life cycle assessment is often perceived as being complicated and the results difficult to interpret by the construction sector. There is also a lack of guidelines regarding the sustainable ratio between the embodied and accumulated operational impact. The scope of this study is to introduce a life cycle assessment method for building refurbishment that utilizes familiar economic performance tools, namely return on investment and annual yield. The aim is to use the introduced method to analyze a case building with a sustainability profile. The building was refurbished in order to reduce its operational energy use. The introduced method is compatible with a theory of minimum sustainable environmental performance that may be developed through backcasting from defined energy and GHG emissions objectives. The proposed approach will hopefully allow development of sustainable refurbishment objectives that can support the choice of refurbishment investments.
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| 10. |
- Nydahl, Helena, 1990-, et al.
(författare)
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Extended building life cycle cost assessment with the inclusion of monetary evaluation of climate risk and opportunities
- 2022
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Ingår i: Sustainable cities and society. - : Elsevier. - 2210-6707. ; 76
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Tidskriftsartikel (refereegranskat)abstract
- The buildings and construction sector account for a significant part of the total energy use and related greenhouse gas emissions. However, climate change mitigation often becomes secondary or completely disregarded in building design assessment as the primary concern of building owners are economic tenability. Therefore, this study introduces an Extended Life Cycle Cost Assessment that include monetary evaluation of climate risk and opportunities in terms of Social Cost of Carbon (SCC). SCC could function as a tax to promote climate change mitigation within e.g. the construction industry. The purpose is to provide a more holistic assessment approach that is easy to relate to if economic tenability is of primary concern in decision making, which can be used to assess building design. Return on invested greenhouse gas emissions is used as an additional or standalone indicator for climate change mitigation. The introduced approach is exemplified by a case study where renovation and new construction are compared with keeping buildings in its original design. The case study show that with or without a flat greenhouse gas tax, renovation is the most climate and cost efficient alternative.
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