| 1. |
- Mishra, A, et al.
(author)
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Diminishing benefits of urban living for children and adolescents' growth and development
- 2023
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In: Nature. - : Springer Science and Business Media LLC. - 1476-4687 .- 0028-0836. ; 615:7954, s. 874-883
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Journal article (peer-reviewed)abstract
- Optimal growth and development in childhood and adolescence is crucial for lifelong health and well-being1–6. Here we used data from 2,325 population-based studies, with measurements of height and weight from 71 million participants, to report the height and body-mass index (BMI) of children and adolescents aged 5–19 years on the basis of rural and urban place of residence in 200 countries and territories from 1990 to 2020. In 1990, children and adolescents residing in cities were taller than their rural counterparts in all but a few high-income countries. By 2020, the urban height advantage became smaller in most countries, and in many high-income western countries it reversed into a small urban-based disadvantage. The exception was for boys in most countries in sub-Saharan Africa and in some countries in Oceania, south Asia and the region of central Asia, Middle East and north Africa. In these countries, successive cohorts of boys from rural places either did not gain height or possibly became shorter, and hence fell further behind their urban peers. The difference between the age-standardized mean BMI of children in urban and rural areas was <1.1 kg m–2 in the vast majority of countries. Within this small range, BMI increased slightly more in cities than in rural areas, except in south Asia, sub-Saharan Africa and some countries in central and eastern Europe. Our results show that in much of the world, the growth and developmental advantages of living in cities have diminished in the twenty-first century, whereas in much of sub-Saharan Africa they have amplified.
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| 2. |
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| 3. |
- Bi, Zhaoxia, et al.
(author)
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InN quantum dots on GaN nanowires grown by MOVPE
- 2014
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In: physica status solidi (c). - : Wiley. - 1862-6351 .- 1610-1642 .- 1610-1634. ; 11, s. 421-424
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Journal article (peer-reviewed)abstract
- In this work, growth of InN quantum dots (QDs) on GaN nanowires (NWs) by metal-organic vapour phase epitaxy is demonstrated, illustrating the feasibility to combine 0D and 1D structures for nitride semiconductors. Selective area growth was used to generate arrays of c-oriented GaN NWs using Si3N4 as the mask material. In general, InN QDs tend to form at the NW edges between the m-plane side facets, but the QD growth can also be tuned to the side facets by controlling the growth temperature and the growth rate. TEM characterization reveals that I1-type stacking faults are formed in the QDs and originate from the misfit dislocations at the InN/GaN interface. Photoluminescence measurement at 4 K shows that the peak shifts to high energy with reduced dot size. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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| 4. |
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| 5. |
- Bi, Zhaoxia, et al.
(author)
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Self-assembled InN quantum dots on side facets of GaN nanowires
- 2018
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In: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 123:16
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Journal article (peer-reviewed)abstract
- Self-assembled, atomic diffusion controlled growth of InN quantum dots was realized on the side facets of dislocation-free and c-oriented GaN nanowires having a hexagonal cross-section. The nanowires were synthesized by selective area metal organic vapor phase epitaxy. A 3 Å thick InN wetting layer was observed after growth, on top of which the InN quantum dots formed, indicating self-assembly in the Stranski-Krastanow growth mode. We found that the InN quantum dots can be tuned to nucleate either preferentially at the edges between GaN nanowire side facets, or directly on the side facets by tuning the adatom migration by controlling the precursor supersaturation and growth temperature. Structural characterization by transmission electron microscopy and reciprocal space mapping show that the InN quantum dots are close to be fully relaxed (residual strain below 1%) and that the c-planes of the InN quantum dots are tilted with respect to the GaN core. The strain relaxes mainly by the formation of misfit dislocations, observed with a periodicity of 3.2 nm at the InN and GaN hetero-interface. The misfit dislocations introduce I1 type stacking faults (...ABABCBC...) in the InN quantum dots. Photoluminescence investigations of the InN quantum dots show that the emissions shift to higher energy with reduced quantum dot size, which we attribute to increased quantum confinement.
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| 6. |
- Ekelund, Ulf, et al.
(author)
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The skåne emergency medicine (SEM) cohort
- 2024
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In: Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine. - London : BioMed Central (BMC). - 1757-7241. ; 32, s. 1-8
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Journal article (peer-reviewed)abstract
- BACKGROUND: In the European Union alone, more than 100 million people present to the emergency department (ED) each year, and this has increased steadily year-on-year by 2-3%. Better patient management decisions have the potential to reduce ED crowding, the number of diagnostic tests, the use of inpatient beds, and healthcare costs.METHODS: We have established the Skåne Emergency Medicine (SEM) cohort for developing clinical decision support systems (CDSS) based on artificial intelligence or machine learning as well as traditional statistical methods. The SEM cohort consists of 325 539 unselected unique patients with 630 275 visits from January 1st, 2017 to December 31st, 2018 at eight EDs in the region Skåne in southern Sweden. Data on sociodemographics, previous diseases and current medication are available for each ED patient visit, as well as their chief complaint, test results, disposition and the outcome in the form of subsequent diagnoses, treatments, healthcare costs and mortality within a follow-up period of at least 30 days, and up to 3 years.DISCUSSION: The SEM cohort provides a platform for CDSS research, and we welcome collaboration. In addition, SEM's large amount of real-world patient data with almost complete short-term follow-up will allow research in epidemiology, patient management, diagnostics, prognostics, ED crowding, resource allocation, and social medicine.
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| 7. |
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| 8. |
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| 9. |
- Khalilian, Maryam, et al.
(author)
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Dislocation-Free and Atomically Flat GaN Hexagonal Microprisms for Device Applications
- 2020
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In: Small. - : Wiley-VCH Verlag. - 1613-6810 .- 1613-6829. ; 16:30
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Journal article (peer-reviewed)abstract
- III-nitrides are considered the material of choice for light-emitting diodes (LEDs) and lasers in the visible to ultraviolet spectral range. The development is hampered by lattice and thermal mismatch between the nitride layers and the growth substrate leading to high dislocation densities. In order to overcome the issue, efforts have gone into selected area growth of nanowires (NWs), using their small footprint in the substrate to grow virtually dislocation-free material. Their geometry is defined by six tall side-facets and a pointed tip which limits the design of optoelectronic devices. Growth of dislocation-free and atomically smooth 3D hexagonal GaN micro-prisms with a flat, micrometer-sized top-surface is presented. These self-forming structures are suitable for optical devices such as low-loss optical cavities for high-efficiency LEDs. The structures are made by annealing GaN NWs with a thick radial shell, reforming them into hexagonal flat-top prisms with six equivalents either m- or s-facets depending on the initial heights of the top pyramid and m-facets of the NWs. This shape is kinetically controlled and the reformation can be explained with a phenomenological model based on Wulff construction that have been developed. It is expected that the results will inspire further research into micron-sized III-nitride-based devices. © 2020 The Authors.
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| 10. |
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| 11. |
- Lind, Lars, et al.
(author)
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Heterogeneous contributions of change in population distribution of body mass index to change in obesity and underweight NCD Risk Factor Collaboration (NCD-RisC)
- 2021
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In: eLife. - : eLife Sciences Publications Ltd. - 2050-084X. ; 10
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Journal article (peer-reviewed)abstract
- From 1985 to 2016, the prevalence of underweight decreased, and that of obesity and severe obesity increased, in most regions, with significant variation in the magnitude of these changes across regions. We investigated how much change in mean body mass index (BMI) explains changes in the prevalence of underweight, obesity, and severe obesity in different regions using data from 2896 population-based studies with 187 million participants. Changes in the prevalence of underweight and total obesity, and to a lesser extent severe obesity, are largely driven by shifts in the distribution of BMI, with smaller contributions from changes in the shape of the distribution. In East and Southeast Asia and sub-Saharan Africa, the underweight tail of the BMI distribution was left behind as the distribution shifted. There is a need for policies that address all forms of malnutrition by making healthy foods accessible and affordable, while restricting unhealthy foods through fiscal and regulatory restrictions.
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| 12. |
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| 13. |
- Zheng, Tenghao, et al.
(author)
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Human Leukocyte Antigen Signatures as Pathophysiological Discriminants of Microscopic Colitis Subtypes
- 2024
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In: Journal of Crohn's and Colitis. - : OXFORD UNIV PRESS. - 1873-9946 .- 1876-4479. ; 18:3, s. 349-359
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Journal article (peer-reviewed)abstract
- Background and Aims: Microscopic colitis [MC] is currently regarded as an inflammatory bowel disease that manifests as two subtypes: collagenous colitis [CC] and lymphocytic colitis [LC]. Whether these represent a clinical continuum or distinct entities is, however, an open question. Genetic investigations may contribute important insight into their respective pathophysiologies. Methods: We conducted a genome-wide association study [GWAS] meta-analysis in 1498 CC, 373 LC patients, and 13 487 controls from Europe and the USA, combined with publicly available MC GWAS data from UK Biobank and FinnGen [2599 MC cases and 552 343 controls in total]. Human leukocyte antigen [HLA] alleles and polymorphic residues were imputed and tested for association, including conditional analyses for the identification of key causative variants and residues. Genetic correlations with other traits and diagnoses were also studied. Results: We detected strong HLA association with CC, and conditional analyses highlighted the DRB1*03:01 allele and its residues Y26, N77, and R74 as key to this association (best p = 1.4 × 10-23, odds ratio [OR] = 1.96). Nominally significant genetic correlations were detected between CC and pneumonia [rg = 0.77; p = 0.048] and oesophageal diseases [rg = 0.45, p = 0.023]. An additional locus was identified in MC GWAS analyses near the CLEC16A and RMI2 genes on chromosome 16 [rs35099084, p = 2.0 × 10-8, OR = 1.31]. No significant association was detected for LC. Conclusion: Our results suggest CC and LC have distinct pathophysiological underpinnings, characterised by an HLA predisposing role only in CC. This challenges existing classifications, eventually calling for a re-evaluation of the utility of MC umbrella definitions.
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| 14. |
- Agell, Jonas, et al.
(author)
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Growth and the public sector : a reply
- 1999
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Reports (other academic/artistic)abstract
- Fölster and Henrekson (1998) claim that they, by addressing a number of econometric problems, can establish that it is likely that economies with a large public sector grow more slowly than economies with a small public sector. But their regressions are fundamentally flawed. Re-estimating their growth equation using theoretically valid instruments, we find that the growth effect of the public sector is statistically insignificant, and much smaller than the point-estimates reported by Fölster and Henrekson. This is consistent with the agnostic conclusion, drawn by us and many others, that cross-country growth regressions are unlikely to give a reliable answer to whether a large public sector is growth promoting or retarding.
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| 15. |
- Agell, Jonas, et al.
(author)
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Growth and the public sector : A reply
- 1999
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In: European Journal of Political Economy. - 0176-2680 .- 1873-5703. ; 15:2, s. 359-366
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Journal article (peer-reviewed)abstract
- Fölster and Henrekson [Fölster, S., Henrekson, M., 1999. Growth and the public sector: A critique of the critics. European Journal of Political Economy 15, 337–358] claim that, by addressing a number of econometric problems, they can establish that it is likely that economies with a large public sector grow more slowly than economies with a small public sector. But their regressions are fundamentally flawed. Re-estimating their growth equation using theoretically valid instruments, we find that the growth effect of the public sector is statistically insignificant, and much smaller than the point-estimates that they report. This is consistent with the agnostic conclusion, drawn by us and others, that cross-country growth regressions are unlikely to provide a reliable answer as to whether a large public sector is growth promoting or retarding.
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| 16. |
- Agell, Jonas, et al.
(author)
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Growth and the public sector : A critical review essay
- 1997
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In: European Journal of Political Economy. - 0176-2680 .- 1873-5703. ; 13:1, s. 33-52
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Journal article (peer-reviewed)abstract
- We review the theoretical and empirical evidence on the relation between growth and the public sector against the background of the current debate on the issue. The evidence is found to admit no conclusion on whether the relation is positive, negative or non-existent. A simple cross-country regression in an OECD sample illustrates how the relation is easily tilted from negative to positive by introducing control variables for initial GDP and the dependent population.
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| 17. |
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| 18. |
- Agell, Jonas, et al.
(author)
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Growth effects of government expenditure and taxation in rich countries : A comment
- 2006
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In: European Economic Review. - : Elsevier BV. - 0014-2921 .- 1873-572X. ; 50:1, s. 211-218
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Journal article (peer-reviewed)abstract
- Fölster and Henrekson (European Economic Review 45 (2001), 1501–1520) argue that “...the more the econometric problems that are addressed, the more robust the relationship between government size and economic growth appears”. But in failing to control for simultaneity and in ignoring issues of sample-selection bias, the regressions reported by Fölster/Henrekson are flawed. Using theoretically valid instruments, we find that the estimated partial correlation between size of the public sector and economic growth is statistically insignificant and highly unstable across specifications. Moreover, since instruments are weak, all hypothesis tests are unreliable. We conclude that cross-country growth regressions are unlikely to come up with a reliable answer to the question of the growth effects of government spending and taxation.
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| 19. |
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| 20. |
- Agell, Jonas, et al.
(author)
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Tillväxt och offentlig sektor
- 1994
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In: Ekonomisk Debatt. - 0345-2646. ; 22:4, s. 373-385
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Journal article (other academic/artistic)abstract
- I den populära svenska debatten hävdas ofta att det finns ett starkt negativt samband mellan offentlig sektor och ekonomisk tillväxt. Den empiriska litteraturen ger emellertid inte något belägg for ett entydigt kausalt samband från stor offentlig sektor till låg tillväxt. Jonas Agell, Thomas Lindh och Henry Ohlsson går i denna artikel igenom den aktuella teoretiska och empiriska forskningen på området. Med några enkla jämförelser för OECD-länderna visar de att andra faktorer än offentlig sektor kan tänkas ha större betydelse för tillväxtskillnader mellan länder.
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| 21. |
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| 22. |
- Amirahmadi, Ali, 1994-, et al.
(author)
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A Masked Language Model for Multi-Source EHR Trajectories Contextual Representation Learning
- 2023
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In: Caring is Sharing - Exploiting the Value in Data for Health and Innovation - Proceedings of MIE 2023. - Amsterdam : IOS Press. - 1879-8365 .- 0926-9630. - 9781643683881 ; 302, s. 609-610, s. 609-610
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Conference paper (peer-reviewed)abstract
- Using electronic health records data and machine learning to guide future decisions needs to address challenges, including 1) long/short-term dependencies and 2) interactions between diseases and interventions. Bidirectional transformers have effectively addressed the first challenge. Here we tackled the latter challenge by masking one source (e.g., ICD10 codes) and training the transformer to predict it using other sources (e.g., ATC codes).
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| 23. |
- Andersson, Ulrika, 1977, et al.
(author)
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Larmar och gör sig till (inledningskapitel)
- 2017
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In: Larmar och gör sig till. - Göteborg : Göteborgs universitet. - 0284-4788. - 9789189673397 ; , s. 11-35
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Book chapter (peer-reviewed)
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| 24. |
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| 25. |
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| 26. |
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| 27. |
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| 28. |
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| 29. |
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| 30. |
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| 31. |
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| 32. |
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| 33. |
- Balogh, Istvan, et al.
(author)
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The importance of work organization on workload and musculoskeletal health - Grocery store work as a model.
- 2016
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In: Applied Ergonomics. - : Elsevier BV. - 1872-9126 .- 0003-6870. ; 53:Part A, s. 143-151
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Journal article (peer-reviewed)abstract
- We have evaluated the consequences of work organization on musculoskeletal health. Using a postal questionnaire, answered by 1600 female grocery store workers, their main work tasks were identified and four work groups were defined (cashier, picking, and delicatessen work, and a mixed group, who performed a mix of these tasks). The crude odds ratios (ORs) for neck/shoulder complaints were 1.5 (95% CI 1.0-2.2), 1.1 (0.7-1.5) and 1.6 (1.1-2.3), respectively, compared to mixed work. Adjusting for individual and psychosocial factors had no effect on these ORs. For elbows/hands, no significant differences were found. Technical measurements of the workload showed large differences between the work groups. Picking work was the most strenuous, while cashier work showed low loads. Quantitative measures of variation revealed for mixed work high between minutes variation and the highest between/within minutes variation. Combining work tasks with different physical exposure levels increases the variation and may reduce the risk of musculoskeletal complaints.
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| 34. |
- Balogh, Istvan, et al.
(author)
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Work-related neck and upper limb disorders - Quantitative exposure-response relationships adjusted for personal characteristics and psychosocial conditions
- 2019
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In: BMC Musculoskeletal Disorders. - : Springer Science and Business Media LLC. - 1471-2474. ; 20:1
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Journal article (peer-reviewed)abstract
- Background: We have previously reported quantitative exposure-response relationships between physical exposures recorded by technical methods, and complaints and diagnoses in the neck/shoulders, and the elbows/hands, based on group data. In the present study the number of workers was doubled, and information on individual factors, and psychosocial working conditions was used. Relationships between various kinds of exposure and response have been analysed in this larger and more detailed sample. Methods: The prevalence of complaints (Nordic Questionnaire) and diagnoses (clinical examination) were recorded in a number of occupational groups within which the participants had similar work tasks, 34 groups of female employees (N = 4733 women) and 17 groups of male employees (N = 1107 men). Age and other individual characteristics were recorded, as well as psychosocial work environment factors (job-content questionnaire) for most participants. Postures and velocities (inclinometry) of the head (N = 505) and right upper arm (N = 510), right wrist postures and velocities (electrogoniometry; N = 685), and muscular activity (electromyography; EMG) in the right trapezius muscle (N = 647) and forearm extensors (N = 396) were recorded in representative sub-groups. Exposure-response relationships between physical exposure and musculoskeletal disorders, adjusted for individual factors with Poisson regression were then calculated. The effect of introducing psychosocial conditions into the models was also assessed. Results: Associations were found between head velocity, trapezius activity, upper arm velocity, forearm extensor activity and wrist posture and velocity, and most neck/shoulder and elbow/hand complaints and diagnoses. Adjustment for age, other individual characteristics and psychosocial work conditions had only a limited effect on these associations. For example, the attributable fraction for tension neck syndrome among female workers with the highest quintile of trapezius activity was 58%, for carpal tunnel syndrome versus wrist velocity it was 92% in men in the highest exposure quintile. Conclusions: Based on the findings, we propose threshold limit values for upper arm and wrist velocity.
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| 35. |
- Benyamine, Isak, 1963-
(author)
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Konstnärliga undervisningspraktiker : Genealogier, diskurser och makt
- 2019
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Doctoral thesis (other academic/artistic)abstract
- This dissertation is about art teaching practices at upper secondary schools with a focus on theatre and at university arts programmes with a focus on film. More specifically, it addresses the factors that have contributed to current teaching practices in art education today and how students and teachers in interaction with each other shape, become part of and identify with the norms and values that emerge through these practices.The overarching question concerns how norms and values emerge as power/knowledge processes in the teaching process. The genealogical study presented examines how art education is constructed at a policy level. The study discusses how, in past eras, investigators, researchers and educators described what students needed to do during their education to develop into professional artists, how teaching practices were designed and justified, and how art was distinct from other activities and forms of knowledge in education. The interaction study presented examines the act of teaching. It discusses how, the participants shape each other and establish norms and values in relation to notions of what art “is” and can be.The conditions of possibilities in art teaching practices has been identified in three discourses. The discourse of conversation governs the format and organisation of the teaching practice. It is assumed that through conversation the students can develop their artistic ability. The discourse of freedom identifies how students submit to the vague, flexible and ever-changing notions of what art signifies. The discourse of production describes how the artistic work in the teaching practice takes precedence over an acquisition of established knowledge.The importance of the participants’ own experiences and feelings, therapeutic conversations, the liberation from conventional education discourses, confession practices and the establishment of a production discourse all emerge as important techniques in art teaching practices. Core values and norms are expressed through these techniques.The study shows that participants in art teaching practices develop the skills of self-evaluation, self-analysis and self-governance. The notion of an individualised, exploratory educational experience clashes with a process that directs the students to align themselves with the shared norms and values of the art world, of its content and expression. Students perceive their artistic output as unique while the art produced can be understood as expression of a normalisation process that strives to maintain the values and norms in art teaching practices. In summery the dissertation shows that the participants’ learning process is of an exploratory nature. Rather than acquiring and assimilating established knowledge, the participants learn by finding their own paths in a knowledge-formation process in which they discover the artistic potential of their own experiences and insights.
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| 36. |
- Bergström, Annika, 1964, et al.
(author)
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Alla dessa val
- 2015
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In: Annika Bergström och Jonas Ohlsson (red) Alla dessa val. Samhälle, Opinion och Medier i Västsverige. - Göteborg : University of Gothenburg. - 9789189673335 ; , s. 9-24
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Book chapter (other academic/artistic)
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| 37. |
- Bergström, Annika, 1964, et al.
(author)
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Brytningstider
- 2014
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In: Bergström, Annika och Ohlsson, Jonas (red) Brytningstider. Samhälle, Opinion och Medier i Västsverige. Göteborg: SOM-institutet vid Göteborgs universitet. - Göteborg : University of Gothenburg. - 9789189673311 ; , s. 9-29
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Book chapter (other academic/artistic)
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| 38. |
- Bergström, Annika, 1964, et al.
(author)
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En region för alla?
- 2013
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In: Bergström, Annika & Jonas Ohlsson (red) En region för alla? Medborgare, människor och medier i Västsverige. - Göteborg : SOM-institutet vid Göteborgs universitet. - 9789189673298 ; , s. 9-30
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Book chapter (other academic/artistic)
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| 39. |
- Bergström, Annika, 1964, et al.
(author)
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Medborgarna om välfärden
- 2012
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In: Medborgarna om välfärden : samhälle, opinion och medier i västsverige : den västsvenska SOM-undersökningen 2011 / Annika Bergström och Jonas Ohlsson (red). - Göteborg : University of Gothenburg. - 9789189673250 ; , s. 9-27
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Book chapter (other academic/artistic)
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| 40. |
- Bi, Zhaoxia, et al.
(author)
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High In-content InGaN nano-pyramids : Tuning crystal homogeneity by optimized nucleation of GaN seeds
- 2018
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In: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 123:2
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Journal article (peer-reviewed)abstract
- Uniform arrays of submicron hexagonal InGaN pyramids with high morphological and material homogeneity, reaching an indium composition of 20%, are presented in this work. The pyramids were grown by selective area metal-organic vapor phase epitaxy and nucleated from small openings in a SiN mask. The growth selectivity was accurately controlled with diffusion lengths of the gallium and indium species, more than 1 μm on the SiN surface. High material homogeneity of the pyramids was achieved by inserting a precisely formed GaN pyramidal seed prior to InGaN growth, leading to the growth of well-shaped InGaN pyramids delimited by six equivalent 10 1 ̄ 1 facets. Further analysis reveals a variation in the indium composition to be mediated by competing InGaN growth on two types of crystal planes, 10 1 ̄ 1 and (0001). Typically, the InGaN growth on 10 1 ̄ 1 planes is much slower than on the (0001) plane. The formation of the (0001) plane and the growth of InGaN on it were found to be dependent on the morphology of the GaN seeds. We propose growth of InGaN pyramids seeded by 10 1 ̄ 1-faceted GaN pyramids as a mean to avoid InGaN material grown on the otherwise formed (0001) plane, leading to a significant reduction of variations in the indium composition in the InGaN pyramids. The InGaN pyramids in this work can be used as a high-quality template for optoelectronic devices having indium-rich active layers, with a potential of reaching green, yellow, and red emissions for LEDs.
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| 41. |
- Bi, Zhaoxia, et al.
(author)
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InGaN Platelets : Synthesis and Applications toward Green and Red Light-Emitting Diodes
- 2019
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In: Nano Letters. - : American Chemical Society. - 1530-6984 .- 1530-6992. ; 19:5, s. 2832-2839
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Journal article (peer-reviewed)abstract
- In this work, we present a method to synthesize arrays of hexagonal InGaN submicrometer platelets with a top c-plane area having an extension of a few hundred nanometers by selective area metal-organic vapor-phase epitaxy. The InGaN platelets were made by in situ annealing of InGaN pyramids, whereby InGaN from the pyramid apex was thermally etched away, leaving a c-plane surface, while the inclined {101Ì1} planes of the pyramids were intact. The as-formed c-planes, which are rough with islands of a few tens of nanometers, can be flattened with InGaN regrowth, showing single bilayer steps and high-quality optical properties (full width at half-maximum of photoluminescence at room temperature: 107 meV for In 0.09 Ga 0.91 N and 151 meV for In 0.18 Ga 0.82 N). Such platelets offer surfaces having relaxed lattice constants, thus enabling shifting the quantum well emission from blue (as when grown on GaN) to green and red. For single InGaN quantum wells grown on the c-plane of such InGaN platelets, a sharp interface between the quantum well and the barriers was observed. The emission energy from the quantum well, grown under the same conditions, was shifted from 2.17 eV on In 0.09 Ga 0.91 N platelets to 1.95 eV on In 0.18 Ga 0.82 N platelets as a result of a thicker quantum well and a reduced indium pulling effect on In 0.18 Ga 0.82 N platelets. On the basis of this method, prototype light-emitting diodes were demonstrated with green emission on In 0.09 Ga 0.91 N platelets and red emission on In 0.18 Ga 0.82 N platelets.
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| 42. |
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| 43. |
- Björk, Jonas, et al.
(author)
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A simple statistical model for prediction of acute coronary syndrome in chest pain patients in the emergency department
- 2006
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In: BMC Medical Informatics and Decision Making. - : Springer Science and Business Media LLC. - 1472-6947. ; 6:28
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Journal article (peer-reviewed)abstract
- Background Several models for prediction of acute coronary syndrome (ACS) among chest pain patients in the emergency department (ED) have been presented, but many models predict only the likelihood of acute myocardial infarction, or include a large number of variables, which make them less than optimal for implementation at a busy ED. We report here a simple statistical model for ACS prediction that could be used in routine care at a busy ED. Methods Multivariable analysis and logistic regression were used on data from 634 ED visits for chest pain. Only data immediately available at patient presentation were used. To make ACS prediction stable and the model useful for personnel inexperienced in electrocardiogram (ECG) reading, simple ECG data suitable for computerized reading were included. Results Besides ECG, eight variables were found to be important for ACS prediction, and included in the model: age, chest discomfort at presentation, symptom duration and previous hypertension, angina pectoris, AMI, congestive heart failure or PCI/CABG. At an ACS prevalence of 21% and a set sensitivity of 95%, the negative predictive value of the model was 96%. Conclusions The present prediction model, combined with the clinical judgment of ED personnel, could be useful for the early discharge of chest pain patients in populations with a low prevalence of ACS.
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| 44. |
- Björk, Jonas, et al.
(author)
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Risk predictions for individual patients from logistic regression were visualized with bar-line charts.
- 2012
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In: Journal of Clinical Epidemiology. - : Elsevier BV. - 1878-5921 .- 0895-4356. ; 65, s. 335-342
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Journal article (peer-reviewed)abstract
- OBJECTIVE: The interface of a computerized decision support system is crucial for its acceptance among end users. We demonstrate how combined bar-line charts can be used to visualize predictions for individual patients from logistic regression models. STUDY DESIGN AND SETTING: Data from a previous diagnostic study aiming at predicting the immediate risk of acute coronary syndrome (ACS) among 634 patients presenting to an emergency department with chest pain were used. Risk predictions from the logistic regression model were presented for four hypothetical patients in bar-line charts with bars representing empirical Bayes adjusted likelihood ratios (LRs) and the line representing the estimated probability of ACS, sequentially updated from left to right after assessment of each risk factor. RESULTS: Two patients had similar low risk for ACS but quite different risk profiles according to the bar-line charts. Such differences in risk profiles could not be detected from the estimated ACS risk alone. The bar-line charts also highlighted important but counteracted risk factors in cases where the overall LR was less informative (close to one). CONCLUSION: The proposed graphical technique conveys additional information from the logistic model that can be important for correct diagnosis and classification of patients and appropriate medical management.
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| 45. |
- Björk, Mikael, et al.
(author)
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Heterostructures in one-dimensional nanowires
- 2002
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In: 7th International Conference on Nanometer-Scale Science and Technology and 21st European Conference on Surface Science.
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Conference paper (peer-reviewed)abstract
- Chemical beam epitaxy has been used to grow III/V nanowires seeded from size selected Au aerosol particles. Both chemically uniform InAs wires as well as InAs wires containing one or several heterostructure interfaces were grown. The interfaces were characterized in a transmission electron microscope revealing atomically sharp interfaces and also that, barriers as thin as only 2-3 monolayers and up to several hundred nanometer could be inserted into homogenous InAs wires. Further more, electrical measurements on both homogenous wires and wires containing heterostructures have been performed to investigate the functionality of nanowire based device elements
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| 46. |
- Björk, Mikael, et al.
(author)
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Nanowire resonant tunneling diodes
- 2002
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In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 81:23, s. 4458-4460
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Journal article (peer-reviewed)abstract
- Semiconductor heterostructures and their implementation into electronic and photonic devices have had tremendous impact on science and technology. In the development of quantum nanoelectronics, one-dimensional (1D) heterostructure devices are receiving a lot of interest. We report here functional 1D resonant tunneling diodes obtained via bottom-up assembly of designed segments of different semiconductor materials in III/V nanowires. The emitter, collector, and the central quantum dot are made from InAs and the barrier material from InP. Ideal resonant tunneling behavior, with peak-to-valley ratios of up to 50:1 and current densities of 1 nA/mum(2) was observed at low temperatures. (C) 2002 American Institute of Physics.
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| 47. |
- Björk, Mikael, et al.
(author)
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One-dimensional heterostructures in semiconductor nanowhiskers
- 2002
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In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 80:6, s. 1058-1060
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Journal article (peer-reviewed)abstract
- We report on the growth of designed heterostructures placed within semiconductor nanowhiskers, exemplified by the InAs/InP material system. Based on transmission electron microscopy, we deduce the interfaces between InAs and InP to be atomically sharp. Electrical measurements of thermionic emission across an 80-nm-wide InP heterobarrier, positioned inside InAs whiskers 40 nm in diameter, yield a barrier height of 0.6 eV. On the basis of these results, we propose new branches of physics phenomena as well as new families of device structures that will now be possible to realize and explore.
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| 48. |
- Björk, Mikael, et al.
(author)
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One-dimensional steeplechase for electrons realized
- 2002
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In: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 2:2, s. 87-89
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Journal article (peer-reviewed)abstract
- We report growth of one-dimensional semiconductor nanocrystals, nanowhiskers, in which segments of the whisker with different composition are formed, illustrated by InAs whiskers containing segments of InP. Our conditions for growth allow the formation of abrupt interfaces and heterostructure barriers of thickness from a few monolayers to 100s of nanometers, thus creating a one-dimensional landscape along which the electrons move. The crystalline perfection, the quality of the interfaces, and the variation in the lattice constant are demonstrated by high-resolution transmission electron microscopy, and the conduction band off-set of 0.6 eV is deduced from the current due to thermal excitation of electrons over an InP barrier.
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| 49. |
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| 50. |
- Björkelund, Anders, et al.
(author)
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Machine learning compared with rule‐in/rule‐out algorithms and logistic regression to predict acute myocardial infarction based on troponin T concentrations
- 2021
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In: Journal of the American College of Emergency Physicians Open. - Hoboken, NJ : John Wiley & Sons. - 2688-1152. ; 2:2
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Journal article (peer-reviewed)abstract
- AbstractObjectiveComputerized decision-support tools may improve diagnosis of acute myocardial infarction (AMI) among patients presenting with chest pain at the emergency department (ED). The primary aim was to assess the predictive accuracy of machine learning algorithms based on paired high-sensitivity cardiac troponin T (hs-cTnT) concentrations with varying sampling times, age, and sex in order to rule in or out AMI.MethodsIn this register-based, cross-sectional diagnostic study conducted retrospectively based on 5695 chest pain patients at 2 hospitals in Sweden 2013–2014 we used 5-fold cross-validation 200 times in order to compare the performance of an artificial neural network (ANN) with European guideline-recommended 0/1- and 0/3-hour algorithms for hs-cTnT and with logistic regression without interaction terms. Primary outcome was the size of the intermediate risk group where AMI could not be ruled in or out, while holding the sensitivity (rule-out) and specificity (rule-in) constant across models.ResultsANN and logistic regression had similar (95%) areas under the receiver operating characteristics curve. In patients (n = 4171) where the timing requirements (0/1 or 0/3 hour) for the sampling were met, using ANN led to a relative decrease of 9.2% (95% confidence interval 4.4% to 13.8%; from 24.5% to 22.2% of all tested patients) in the size of the intermediate group compared to the recommended algorithms. By contrast, using logistic regression did not substantially decrease the size of the intermediate group.ConclusionMachine learning algorithms allow for flexibility in sampling and have the potential to improve risk assessment among chest pain patients at the ED.
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