| 1. |
- Ekberg, Joakim, et al.
(författare)
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Impact of precautionary behaviors during outbreaks of pandemic influenza : modeling of regional differences
- 2009
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Ingår i: AMIA Annual Symposium Proceedings. - Rockville Pike, Bethesda MD, 20894 USA : American Medical Informatics Association. - 1942-597X. ; 2009, s. 163-167
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Tidskriftsartikel (refereegranskat)abstract
- Using time geographic theory for representation of population mixing, we set out to analyze the relative impact from precautionary behaviors on outbreaks of pandemic influenza in Europe and Asia. We extended an existing simulator environment with behavioral parameters from a population survey to model different behaviors. We found that precautionary behaviors even among a minority of the population can have a decisive effect on the probability of the outbreak to propagate. The results also display that assumptions strongly influences the outcome. Depending on the interpretation of how many "children" are kept from "school", R(0) changes from a range where outbreak progression is possible to a range where it is improbable in both European (R(0)=1.77/1.23) and Asian (R(0)=1.70/1.05) conditions. We conclude that unprompted distancing can have a decisive effect on pandemic propagation. An important response strategy can be to promote voluntary precautionary behavior shown to reduce disease transmission.
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| 2. |
- Timpka, Toomas, et al.
(författare)
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Population-based simulations of influenza pandemics : validity and significance for public health policy
- 2009
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Ingår i: BULLETIN OF THE WORLD HEALTH ORGANIZATION. - 0042-9686 .- 1564-0604. ; 87:4, s. 305-311
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Tidskriftsartikel (refereegranskat)abstract
- Objective To examine the validity and usefulness of pandemic simulations aimed at informing practical decision-making in public health. Methods We recruited a multidisciplinary group of nine experts to assess a case-study simulation of influenza transmission in a Swedish county. We used a non-statistical nominal group technique to generate evaluations of the plausibility, formal validity (verification) and predictive validity of the simulation. A health-effect assessment structure was used as a framework for data collection. Findings The unpredictability, of social order during disasters was not adequately addressed by simulation methods; even minor disruptions of the social order may invalidate key infrastructural assumptions underpinning current pandemic simulation models. Further, a direct relationship between model flexibility and computation time was noted. Consequently, simulation methods cannot, in practice, support integrated modifications of microbiological, epidemiological and spatial submodels or handle multiple parallel scenarios. Conclusion The combination of incomplete surveillance data and simulation methods that neglect social dynamics limits the ability of national public health agencies to provide policy-makers and the general public with the critical and timely information needed during a pandemic.
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| 3. |
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| 4. |
- Erixon Arreman, Inger, 1954-, et al.
(författare)
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Employability of Swedish student teacher alumni
- 2008
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Ingår i: Teacher education policy in Europe. - Umeå : Institutionen för tillämpad utbildningsvetenskap, Umeå universitet. - 9789172646001 ; , s. 157-181
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- In recent years, “employability” has become an increasingly central concept in higher education, in no small part since it constitutes an important aspect of the Bologna Process. The project “Teachers’ employability” is a project carried out on behalf of the Faculty of Teacher Education at Umeå University – one of the major providers of teacher education in Sweden – and is a part of a broader university effort to evaluate and increase employability. The aim of the project is to examine the situation of the university’s student teachers after graduation, as well as to find out how the former students and their employers view their education. The study is based on the longitudinal individual database ASTRID, questionnaires and interviews. This paper reports findings from the project, focusing on 1) employment situation, income development and mobility patterns of recent alumni (class of 2000) and 2) primary employers’ (school leaders) view of the quality and usefulness of the present teacher education curriculum. While employability is generally high, there are significant differences in career paths and income development, depending on for instance type of degree and place of residence. The interviews with school leaders reveal that although the present curriculum is perceived to have certain general limitations, it is viewed as more suited for pre-school rather than comprehensive school and gymnasium teacher education.
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| 5. |
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| 6. |
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| 7. |
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| 8. |
- Hanke, Michael, et al.
(författare)
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Stability Analysis of a Degenerate Hyperbolic System Modelling a Heat Exchanger
- 2007
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Ingår i: Mathematics and Computers in Simulation. - : Elsevier BV. - 0378-4754 .- 1872-7166. ; 74:1, s. 8-19
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Tidskriftsartikel (refereegranskat)abstract
- Mathematical modelling of a heat exchanger in a carbon dioxide heat pump, an evaporator, is considered. A reduced model, called the the zero Mach-number limit, is derived from the Euler equations of compressible liquid flow through elimination of time scales associated with sound waves. The well-posedness of the resulting partial differential-algebraic equation (PDAE) is investigated by analysis of a frozen coefficient linearisation as well as by numerical experiments. The linear stability analysis is done through transformation to a canonical form with one hyperbolic component and one parabolic block of dimension 2. Using this canonical form it is seen how to prescribe boundary and initial data and an energy estimate is derived. Numerical experiments on the nonlinear PDAE using a finite difference spatial discretisation support the linear stability analysis.
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| 9. |
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| 10. |
- Haugen, Katarina, et al.
(författare)
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Changes in accessibility 1995-2005
- 2009
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Ingår i: Paper presented at the NECTAR Cluster on Accessibility, Cagliari, Italy. - Cagliari.
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Konferensbidrag (refereegranskat)
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| 11. |
- Helgesson, Anita, et al.
(författare)
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Coordinated care planning for elderly patients using videoconferencing
- 2005
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Ingår i: Journal of Telemedicine and Telecare. - 1357-633X. ; 11:2, s. 85-92
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Tidskriftsartikel (refereegranskat)abstract
- We studied the transfer of information during coordinated care planning between a university hospital and a local health care centre/social welfare department about 35 km away. During a seven-month study period, 10 sessions were conducted by videoconferencing and seven sessions were conducted by face-to-face conferencing. Videoconferencing reduced the time required for each coordinated care-planning session from an average of 60 to 45 min. There was also an increase in the number of participating professional categories. Travel time for the staff in the face-to-face group was 60-180 min each. Use of a care-planning report during the sessions resulted in improved quality of documentation, which contributed to better care following discharge. The technical problems that occurred did not detract from the beneficial experience of participating. Interviews with next of kin showed that they had been able to influence the content of the care during the care-planning sessions. Videoconferencing proved useful in coordinated care planning. It resulted in time saved due to reduced travel time, participation by more staff categories and an enhancement of the documentation quality.
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| 12. |
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| 13. |
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| 14. |
- Holm, Einar, et al.
(författare)
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SVERIGE
- 2007
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Ingår i: Modelling our Future. - : Elsevier, Amsterdam. - 9780444530059 ; , s. 543-549
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Bokkapitel (refereegranskat)
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| 15. |
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| 16. |
- Häggström Lundevaller, Erling, et al.
(författare)
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Spatial dynamic micro-simulation of demographic development
- 2007
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Ingår i: 1st General Conference of the International Microsimulation Association.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In a world of changing demographical patterns, tools for keeping track of these changes are of great importance. Different regions are in different stages of the demographic transition and are affected differently of migration patterns. A tool to project the demographic development at a regional level is therefore of great importance. This article we discusses the demographic development in the county Västerbotten in Sweden and in that context why and how a micro simulation model can be used for these purposes.
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| 17. |
- Lindgren, Urban, et al.
(författare)
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Analyzing Socio-Economic Impacts of Large Investments by Spatial Microsimulation
- 2007
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Ingår i: 1st General Conference of the International Microsimulation Association.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In the near future, a nuclear waste repository will be located in either Östhammar or Oskarshamn, two Swedish municipalities. This is a major investment that is likely to have socio-economic implications at the local level for several decades. In order to analyze the indirect local effects of such large investments, a spatial and dynamic microsimulation model (SVERIGE 3) has been constructed. The model simulates demographic events (e.g., fertility and migration) as well as education and the labor market. In this study, the simulation model is utilized to evaluate a number of scenarios comprising various potential investments in Östhammar, one of which is the nuclear waste repository. As part of the study, the direct local effect of the investments was estimated. When running the model, the estimated direct local effects function as exogenous economic input to concerned labor market sectors. The results of the simulations indicate that investments such as the nuclear waste repository will have some economic and demographic effects. However, infrastructure projects that increase accessibility seem to generate more profound and long-lasting effects at the local level. A municipality such as Östhammar, located close the Stockholm metropolitan area, may be especially likely to benefit by such infrastructure investments.
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| 18. |
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| 19. |
- Lindgren, Urban, et al.
(författare)
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Slutförvaret och det lokala näringslivet : en undersökning om upphandlingsbehov och leverantörskapacitet i Östhammar och Oskarshamn
- 2006
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Ingår i: Samhällsforskning 2006. - Stockholm : SKB. - 9197614130 ; , s. 48-65
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Bokkapitel (refereegranskat)abstract
- Studier av upphandlingar till stora investeringar i industriell produktion och infrastruktur har visat att storleken på de lokala ekonomiska spridningseffekterna beror på vilken typ av investering det är och var den äger rum. Exempelvis tenderar de lokala effekterna att vara större i befolkningstäta områden med stort och diversifierat näringsliv. I den här presentationen belyser Urban Lindgren och Magnus Strömgren de ekonomiska spridningseffekter som etableringen av slutförvaret kan föra med sig när det byggs i Oskarshamns eller Östhammars kommun.
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| 20. |
- Lindgren, Urban, et al.
(författare)
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Slutförvarets lokala effekter på befolkning och sysselsättning i Östhammar och Oskarshamn
- 2007
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- I denna studie ställs frågan om vilka lokala spridningseffekter investeringen i ett slutförvar för använt kärnbränsle kan komma att få. För närvarande pågår platsundersökningar i Östhammar och Oskarshamn och slutförvaret kommer med stor sannolikhet att byggas i någon av dessa kommuner. Genomförandet av slutförvarsprojektet består av ett flertal olika investeringar vars lokaliseringsförutsättningar skiljer sig åt. Förutom slutförvaret för använt kärnbränsle ingår även utbyggnad av SFR (Slutförvar för radioaktivt driftavfall) och byggandet av en inkapslingsanläggning och en "kapselfabrik", för montering av kapslar. Utbyggnaden av SFR måste ske i Östhammar då SFR redan finns där och inkapslingsanläggningen bör enligt SKB byggas i anslutning till Clab (Centralt mellanlager för använt kärnbränsle) som är förlagt till Oskarshamn. Dessa omständigheter betyder att delar av den totala investeringssumman för slutförvaret (cirka 15 miljarder kronor) redan nu går att knyta till specifika platser.Resultaten från en enkätundersökning visar att näringslivet i de två kommunerna skiljer sig åt med avseende på möjligheter att leverera varor och tjänster till slutförvarsinvesteringen. Vid en jämförelse mellan leverantörskapacitet och upphandlingsbehov förefaller det som om att det lokala näringslivet i Oskarshamn har en sammansättning som bättre matchar slutförvarsinvesteringens behov.De lokala spridningseffekterna av slutförvarsinvesteringen begränsas emellertid inte till de aktiviteter som härrör till byggnation av anläggningar. Drift och efterarbeten vid anläggningarna ger också inkomster och arbetstillfällen. Slutförvaret med sidoinvesteringar kommer att generera spridningseffekter i både Östhammar och Oskarshamn oavsett i vilken kommun slutförvaret lokaliseras. Däremot blir de ekonomiska spridningseffekterna olika på grund av skillnader i det lokala näringslivets leverantörskapacitet och förutbestämda lokaliseringar av vissa sidoinvesteringar. Analyserna antyder bland annat att de lokala spridningseffekterna blir tämligen stora i Oskarshamn om Östhammar får slutförvaret, medan effekterna i Östhammar blir ytterst begränsade om slutförvaret placeras i Oskarshamn.
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| 21. |
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| 22. |
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| 23. |
- Strömgren, Magnus, et al.
(författare)
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On the numerical approximation of a degenerated hyperbolic system
- 2009
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Ingår i: Mathematics and Computers in Simulation. - : Elsevier BV. - 0378-4754 .- 1872-7166. ; 79:5, s. 1585-1602
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Tidskriftsartikel (refereegranskat)abstract
- The heat exchanger in a heat pump system may be conveniently described by a degenerated hyperbolic system, namely the zero Mach-number limit of the Euler equations. This leads to a mixed hyperbolic/parabolic system with coupled time-dependent boundary conditions. We propose a method-of-lines discretisation by using an upwinding scheme. We derive stability estimates for the linearisation with frozen coefficients. The resulting differential-algebraic equation has a perturbation index of 2 and a weak instability with respect to the space step size. The latter property is validated experimentally even for the nonlinear system. In contrast, the perturbation index did not exceed one in the numerical experiments.
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| 24. |
- Strömgren, Magnus
(författare)
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Some PDAE aspects of the numerical simulation of a CO2 heat pump
- 2006
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- We consider network modelling and numerical simulation of a simple CO2 heat pump consisting of a compressor, a valve and two heat exchangers. In a first step we investigate analytical and numerical properties of the heat exchanger model. The heat exchanger model is derived from the Euler equations under the assumption that the velocity of the refridgerant flow is small compared to the local speed of sound. While the Euler equations form a hyperbolic system, the character of the new system, called The zero Mach number limit of the Euler equations, is unclear. The lack of a time derivative in the momentum equation makes the heat exchanger model by itself a PDAE system. We analyse a frozen-coefficient linearisation of the heat exchanger model by transformation to a canonical form. The canonical form reveales that the system is equivalent to a hyperbolic equation and a parabolic block. The parabolic block is equivalent to a parabolic equation and an algebraic-differential relation, similar to the system that results when the heat equation ut = uxx + f is written as a first order system. We prove a stability estimate suggesting that the solution is more sensitive to perturbations, especially in time-dependent boundary conditions, than is indicated by previous results. Furthermore, we consider semidiscretisation of the linearised heat exchanger model. In a method of lines approach using collocation at the gridpoints, we suggest that it is possible to use a simple first order difference scheme taking into account the direction of the flow and the boundary conditions. We show that using this difference scheme, the solution to the semidiscrete equations satisfies a discrete analogue to the stability estimate in the continuous case. The results of the linear analysis is verified in numerical experiments with the nonlinear heat exchanger model.
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