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- Sundberg, Marcus
(författare)
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Spatial computable general equilibrium modelling : static and dynamic approaches
- 2005
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis concerns both static and dynamic modeling in a spatial computable general equilibrium setting. First, we have applied a static framework for the assessment of economic impacts of the Öresund bridge. Secondly, we make an attempt to enhance the static framework through the introduction of economic dynamics. In the first paper we study the economic impacts of the Öresund bridge. We aim to quantify regional welfare effects as well as effects on regional production and trade. We calibrate a static spatial computable general equilibrium model to economic data representing the Öresund region. In particular we have calibrated a pre-bridge barrier parameter which enables us to study possible barrier reduction effects from the bridge. We present results both as effects of cross strait transport cost reductions and of barrier reductions. It is found that the potential impacts of removing barriers to trade may outweigh the impacts solely due to reduced transport costs. In the second paper we consider different specifications of a dynamic spatial computable general equilibrium model. In particular we are interested in the effects of different, commonly used assumptions on transition dynamics of such a model. We have specified models with different assumptions regarding capital mobility, the utility specification of the households and assumptions regarding perfect foresight or myopia. A number of simulations have been performed with these models in order to observe policy responses and in order to be able to make specification comparisons of the different models based on those responses. We consider the time in takes for the dynamic models to converge toward the long term steady state to be of importance for welfare assessment of policies and find that convergence may be slow depending on both the model and the policy considered.
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- Westin, Carl-Fredrik, et al.
(författare)
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Three-dimensional adaptive filtering in magnetic resonance angiography
- 2001
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Ingår i: Journal of Magnetic Resonance Imaging. - : Wiley. - 1053-1807 .- 1522-2586. ; 14:1, s. 63-71
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Tidskriftsartikel (refereegranskat)abstract
- In order to enhance 3D image data from magnetic resonance angiography (MRA), a novel method based on the theory of multidimensional adaptive filtering has been developed. The purpose of the technique is to suppress image noise while enhancing important structures. The method is based on local structure estimation using six 3D orientation selective filters, followed by an adaptive filtering step controlled by the local structure information. The complete filtering procedure requires approximately 3 minutes of computational time on a standard workstation for a 256 × 256 × 64 data set. The method has been evaluated using a mathematical vessel model and in vivo MRA data (both phase contrast and time of flight (TOF)). 3D adaptive filtering results in a better delineation of small blood vessels and efficiently reduces the high-frequency noise. Depending on the data acquisition and the original data type, contrast-to-noise ratio (CNR) improvements of up to 179% (8.9 dB) were observed. 3D adaptive filtering may provide an alternative to prolonging the scan time or using contrast agents in MRA when the CNR is low.
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- Arnek, Magnus, 1965-
(författare)
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Empirical Essays on Procurement and Regulation
- 2002
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Essay 1: This paper reports the results of an empirical analysis of the effect of competitive tendering on road operation and maintenance expenses in Sweden. Contrasts of procurement expenses between operation and maintenance contracts let in competitive tendering and similar sole-sourced contracts indicate that competitive tendering reduces procurement expenses by 22-27 percent. Further, there is no evidence that service quality is lower for tendered contracts than for non-tendered contracts.Essay 2: Data on firms’ entries in the Swedish National Road Administration’s procurement auctions of road maintenance are used to estimate what factors determine potential bidders decisions to enter. I find the number of potential bidders to affect the probability for firms to bid. Increasing potential competition tends to decrease the probability of firms participating in the auctions. Other factors affecting entry decisions are firm size, project size, time limit for the submission of bids, and time span of the contracts that are up for tender. Essay 3: (With Per Johansson) This paper presents the results of an empirical analysis of the effect of contract form on the costs of road maintenance in Sweden. Firms’ bidding and production behavior under two different contract forms are compared using bid and cost data from the Swedish National Road Administration’s procurement of road operation and maintenance. Both contracts are variants of a fixed-price contract that differ in the extent of risk imposed on firms, and in the incentives for cost reductions they provide. We find evidence of a considerable moral-hazard effect. Thus, contract form affects behavior and hence expenses.Essay 4: Yardstick competition is a regulatory mechanism, which, according to theory, could induce efficient price regulation in a whole industry. This paper reports results from a laboratory experiment testing this theory. Specifically, the paper reports the results from an investigation of whether yardstick competition can work in situations with few firms. It is found that the theory of yardstick competition predicts behavior well. The average outcome does, however, depend on the number of participating firms: the yardstick competition model predicts behavior better when the number of firms is four that when they are two. Essay 5: I test whether violations of expected utility theory in an Allais Paradox environment are sensitive to payoff size. I find a positive relationship between the fraction of people violating expected utility theory and payoff size.
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- Bergkvist, Erik, et al.
(författare)
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Estimation of gravity models by OLS estimation, NLS estimation, Poisson and neural network specifications
- 2001
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Ingår i: New analytical advances in transportation and spatial dynamics. - Aldershot : Ashgate. - 1840148632 - 9781315190921 - 9781138727250 ; , s. 135-155
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Bokkapitel (refereegranskat)abstract
- When assessing infrastructure investment, it is crucial to forecast the flows on the links after the suggested improvements. In freight flow analysis, the impact on the flows in the network is conditional on the size of the investment and the complexity of the network. If the investment has a critical impact on the flows, the change may be substantial and hard to predict by linear models. In economic geography and regional economics, the gravity model has gained wide acceptance as a reasonable (although simple) model of spatial interaction between nodes in a network (Haynes and Fotheringham, 1984 or Sen and Smith, 1995).
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- Bergkvist, Erik, et al.
(författare)
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Regional valuation of infrastructure and transport attributes for Swedish road freight
- 2001
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Ingår i: The annals of regional science. - Berlin : Springer Berlin/Heidelberg. - 0570-1864 .- 1432-0592. ; 35:4, s. 547-560
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Tidskriftsartikel (refereegranskat)abstract
- Is it possible to identify regional differences among shippers in their valuation of infrastructure improvements? In this study, the question is analysed using a random utility approach, where parameters are estimated by a logit model. Data consist of a Swedish stated-preference study from 1992. The results indicate that regional differences exist, but that a considerable heterogeneity in the empirical data means that in some cases the results are not robust. However, when industrial mix, shipping distance, and goods values are held constant, the analysis still indicates the existence of regional differences. Independently of the limitations in the results, the study has implications for any infrastructure benefit analysis where parameters from spatial averages are used. The results are based on short-term decisions, and one should recognise that parameters may vary in the mid- and long-term.
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- Edlund, Johanna, 1983-, et al.
(författare)
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BIDs i Sverige : Internationella erfarenheter av "Business Improvement Districts"
- 2009
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Business Improvement Districts (BID) finns idag i olika former på flera internationella fastighetsmarknader. Ett BID omfattar ett väl avgränsat område i en stad inom vilket en hållbar samverkan mellan fastigheter, handel, boende och en kommun är formaliserad. Syftet är att utveckla områdets affärsmöjligheter eller områdets attraktivitet i en vidare bemärkelse. Med ett BID kan en kommun stärka marknadens effektivitet genom att begränsa incitamenten till ”snålskjutsbeteende” bland fastighetsägare, handlare eller andra aktörer. Ett BID reducerar därmed t.ex. behovet för fastighetsägare att ta över närliggande fastigheter i området för att möjliggöra förnyelse. Mångfalden på stadens fastighetsmarknad kan således bevaras. I denna rapport studeras internationella motiv, lagstiftning, positiva och negativa erfarenheter av BIDs. Här diskuteras även något hur BIDs skulle kunna utformas i Sverige. Inom nuvarande lagstiftning, PBL och Anläggningslagen, är det inte uppenbart möjligt att införa en sådan tidsbegränsad samverkan mellan flera fastigheter (varav några kan ha motsatt sig samverkan). Rapporten indikerar även vilka förändringar som kan krävas i svensk lagstiftning för att BID ska bli en möjlig policyåtgärd för kommuner i Sverige.
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