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- Bengtsson, Boel, et al.
(author)
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A new generation of algorithms for computerized threshold perimetry, SITA
- 1997
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In: Acta Ophthalmologica Scandinavica. - : Wiley. - 1395-3907. ; 75:4, s. 75-368
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Journal article (peer-reviewed)abstract
- PURPOSE: The purpose of this work was to develop a new family of test algorithms for computerized static threshold perimetry which significantly reduces test time without any reduction of data quality.METHODS: A comprehensive visual field model constructed from available knowledge of normal and glaucomatous visual fields is continuously updated during testing. The model produces threshold estimates and also estimates of the certainty to which the threshold is known at each point. Testing is interrupted at each test location at predetermined levels of threshold certainty. New time-saving methods are employed for estimation of false answers, and test pacing is optimized. After completion of the test, all threshold estimates are re-computed, taking into account the complete body of patient responses. Computer simulations were used to optimize the different parameters of the new algorithms, to evaluate the relative importance of those parameters, and to evaluate the performance of the algorithm as a whole in comparison with a standard algorithm.RESULTS: Simulated test results obtained with this algorithm were slightly more accurate than those of the Humphrey Full Threshold test algorithm. The number of simulated stimuli presented was reduced by an average of 29% in normal fields and 26% in glaucomatous fields. Actual clinical test time should be further reduced, since the influence of the improved timing algorithm was not included in the simulations.CONCLUSIONS: We applied new methods which take available knowledge of visual field physiology and pathophysiology into account, and employ modern computer-intensive mathematical methods for real time estimates of threshold values and threshold error estimates. In this way it was possible to design a family of testing algorithms which significantly reduced perimetric test time without any loss of quality in results.
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| 4. |
- Heijl, Anders, et al.
(author)
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On weighted visual field indices
- 1992
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In: Graefe's Archive for Clinical and Experimental Ophthalmology. - 1435-702X. ; 230:4, s. 397-400
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Journal article (peer-reviewed)
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| 5. |
- Heijl, Anders, et al.
(author)
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The effect of perimetric experience in normal subjets
- 1989
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In: Archives of Ophthalmology. - 0003-9950. ; 107:1, s. 81-86
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Journal article (peer-reviewed)abstract
- Two groups of normal subjects were submitted to repeated automated static threshold perimetry. Perimetric results were strongly affected by the level of experience in some subjects; in the majority, however, the effect of experience was small. Initial field tests often showed high numbers of depressed points. Sensitivity increased with perimetric training, particularly between the first sessions. Those subjects who improved most started low, gradually approaching normal levels with experience. Learning effects were more pronounced peripherally than paracentrally and "untrained" fields characteristically showed concentric contraction with numerous points with low sensitivity peripherally. An important practical conclusion is to allow repeated testing of all inexperienced patients in whom initial fields do not agree with clinical findings. A chart showing a concentrically narrowed field should be viewed with particular suspicion. Furthermore, a single initial field may constitute an inadequate baseline for clinical follow-up.
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| 6. |
- Heijl, A, et al.
(author)
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Visual field interpretation with empiric probability maps
- 1989
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In: Archives of Ophthalmology. - : American Medical Association (AMA). - 0003-9950. ; 107:2, s. 8-204
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Journal article (peer-reviewed)abstract
- Automated visual field charts may be difficult to interpret partly because of the magnitude and complex nature of normal threshold variability. We devised two types of empiric probability maps in which this variability is taken into account and the significances of measured threshold values are displayed. These maps are highly sensitive to nonobvious but significant paracentral field loss but will at the same time deemphasize false-positive patterns commonly found more peripherally. They also frequently show field defects before these are obvious in conventional threshold printouts. In addition, they differentiate between generalized loss of sensitivity and localized field defects.
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| 7. |
- Kadefors, Anna, Professor, 1962-, et al.
(author)
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Relational contracting in Nordic construction – a comparative longitudinal account of institutional field developments
- 2024
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In: International Journal of Managing Projects in Business. - : Emerald Publishing. - 1753-8378 .- 1753-8386. ; 17:8, s. 22-46
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Journal article (peer-reviewed)abstract
- Purpose: Relational contracting is increasingly being applied to complex and uncertain construction projects. However, it has proved hard to achieve stable performance and industry-level learning in this field. This paper employs an institutional perspective to analyze how legitimacy for relational contracting has been produced and challenged in Denmark, Finland, Norway and Sweden, including implications for dissemination and learning. Design/methodology/approach: A collaborative case study design is used, where longitudinal accounts of the developments in relational contracting over more than 25 years in four Nordic countries were developed by scholars based in each country. The descriptions are underpinned by literature sources from research, practice and policy. Findings: The countries share similar problem perceptions that have triggered the de-institutionalization of traditional contracting practices. Models and policies developed elsewhere are important sources of knowledge and legitimacy. Most countries have seen pendulum movements, where dissemination of relational contracting is followed by backlashes when projects fail to meet projected outcomes. Before long, however, relational contracting tends to re-emerge under new labels and in slightly new forms. Such a proliferation of concepts presents further obstacles to learning. Successful institutionalization is found to rely on realistic goals in combination with broad competence development at the organizational and industry levels. Practical implications: In seeking inspiration from other countries, policymakers should go beyond contract models to also consider strategies to manage industry-level learning. Originality/value: The paper provides a unique longitudinal cross-country perspective on the field of relational contracting. As such, it contributes to the small stream of literature on long-term institutional change in the construction sector.
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| 8. |
- Karrbom Gustavsson, Tina, 1973-, et al.
(author)
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Procurement Research: Current State and Future Challenges in the Nordic Countries
- 2019
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In: 10th Nordic Conference on Construction Economics and Organization (Emerald Reach Proceedings Series, Volume 2). - : Emerald Group Publishing Limited. ; , s. 195-204, s. 195-204
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Conference paper (peer-reviewed)abstract
- PurposeThe purpose of the study is to map previous and current construction procurement research to further develop the research in the Nordic counties.Design/Methodology/ApproachMapping of previous and current research based on search in national database. The analysis is based on research perspectives, empirical contexts and research methods.FindingsThat the blind spots are partly overlapping, but that there is potential for knowledge transfer in some areas. There is also the potential for a Nordic research program on one or several of the blind spots.Research Limitations/ImplicationsThe study is limited to PhD and licentiate-thesis reports in Norway and Sweden. Further research should include the other Nordic countries and a more extensive literature review including journal articles to broaden the scope. Findings have implications on collaborative Nordic research initiatives, knowledge transfer and in a longer perspective on the level of procurement knowledge in industry and society.Practical ImplicationsFindings provide a base for future research collaborations, initiatives and applications.Originality/ValueFindings provide a comprehensive understanding of construction procurement research in the Nordic countries, starting with Norway and Sweden. This understanding is needed for developing research collaborations and applications.
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| 9. |
- Lindow, Helma, et al.
(author)
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Integrerat kustzonsystem för Bohusläns skärgård
- 2004
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Reports (other academic/artistic)abstract
- SMHI har i samarbete med Länsstyrelsen i västra Götaland implementerat Kustzonssystemet i Bohusläns skärgård. Arbetet har pga. av sin omfattning indelats i två etapper. Kustzonssystemet är ett integrerat modellsystem där belastningen på kusten från land och atmosfär fastställs m.h.a. modeller. Syftet med kustzonssystemet är att modellerna skall vara så enkla som möjligt, för att kunna skapa långa tidsserier, och samtidigt kunna beskriva miljötillståndet i skärgården tillräckligt väl så att modellsystemet kan användas för exempelvis scenarioberäkningar. Bohuskusten kännetecknas av ett, på sina håll, komplicerat fjordsystem. Kustzonsmodellen är en s.k. en-dimensionell modell, som löser upp modellvariablerna i djupled, men beräknar ett horisontellt medelvärde i sitt område. För att kunna lösa upp de horisontella gradienterna i området måste modellområdet delas in i flertalet delbassänger. Indelningen av Kustzonsmodellens delbassänger följer i stort sett SVAR-indelningen. Detta innebär att för den norra delen av skärgården består modellen av 30 delbassänger. I den södra delen har vissa förenklingar kunnat göras, och några havsområden har kunnat slås samman i modellen och behandlats som en delbassäng. Genom dessa sammanslagningar har den södra skärgården delats in i 27 delbassänger. Modellen har simulerat en längre tidsserie i båda områdena. Observationer i Skagerack och Kattegatt driver modellen från öppna havet. En omfattande validering av modellen har genomförts m.h.a. observationer från Bohuskustens kontrollprogram. Därefter har in- och utflöden beräknats i varje bassäng för såväl total-kväve som total-fosfor.
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| 10. |
- Olsson, Jonny, et al.
(author)
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A perimetric learner's index
- 1997
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In: Acta Ophthalmologica Scandinavica. - : Wiley. - 1395-3907. ; 75:6, s. 665-668
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Journal article (peer-reviewed)abstract
- Purpose: Certain individuals need earlier perimetric experience before producing normal fields on automated static threshold perimetry. Mid-peripheral depressions and an unaffected central field are typical findings in such cases. We have devised a learner's index, to detect defect patterns that may be due to such perimetric inexperience. Methods: The central visual field was partitioned into 5 concentric zones and averages of deviations from the age-corrected normal threshold values were studied in each zone. The third test session in 74 randomly selected normal subjects provided an experienced reference material. Visual field results typical of normal individuals lacking perimetric experience were represented by the first field test obtained from each of 7 subjects ('learners') from the same group, who showed significant learning during three test sessions. A linear discriminant function, learner's index, was constructed that discriminates between typically experienced and typically inexperienced field results in normals. Results: Average deviation from age-corrected normal threshold increased with increasing eccentricity in the learner's initial fields. Clinical examples illustrate the intended use of the new index. Conclusions: The learner's index highlights those first field tests from eyes with normal visual fields, that deviate significantly from a normal experienced result in the direction of a learner's result. Patients showing significant learner's index are candidates for repeated visual field testing.
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