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Wahlström, Jens
Publications (10 of 11) Show all publications
Hallman, D., Mathiassen, S. E., Heiden, M., Birk Jørgensen, M., Holtermann, A., Rudolfsson, T., . . . Wahlström, J. (2018). Symposium: Arbete, individ och nacksmärta: Forskning vid Forte-centret “Kroppen i arbete – från problem till potential”. In: Per Lindberg (Ed.), FALF KONFERENS 2018 Arbetet - problem eller potential för en hållbar livsmiljö? 10-12 juni 2018 i Gävle: Program och Abstracts. Paper presented at FALF KONFERENS 2018 'Arbetet - problem eller potential för en hållbar livsmiljö?', 10-12 Juni 2018, Gävle (pp. 102). Gävle: Gävle University Press
Open this publication in new window or tab >>Symposium: Arbete, individ och nacksmärta: Forskning vid Forte-centret “Kroppen i arbete – från problem till potential”
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2018 (Swedish)In: FALF KONFERENS 2018 Arbetet - problem eller potential för en hållbar livsmiljö? 10-12 juni 2018 i Gävle: Program och Abstracts / [ed] Per Lindberg, Gävle: Gävle University Press , 2018, p. 102-Conference paper, Oral presentation with published abstract (Refereed)
Abstract [sv]

Besvär ifrån kroppens muskler och leder såsom nack- och ryggbesvär är fortfarande ett stort problem inom arbetslivet. Muskuloskeletal diagnos är den vanligaste orsaken till lång sjukfrånvaro inom privat sektor och näst vanligast inom kommuner och landsting. Orsakerna till dessa besvär kan vara relaterade till exponering både under arbete och på fritid, men även till individfaktorer. Vår forskargrupp har en bred ansats för att fylla kunskapsluckor inom detta område och kommer att presentera resultat från flera forskningsprojekt i symposiet Arbete, individ och nacksmärta.

Långvarigt sittande har blivit alltmer vanligt förekommande i många yrkesgrupper. Långvarigt sittande och låg fysisk aktivitet har också uppmärksammats som ett betydande hälsoproblem i dagens arbetsliv och även som en möjlig riskfaktor för smärta i nacke-skuldra. Men forskningen om betydelsen av långvarigt sittande för smärta i nacke-skuldra är fortfarande begränsad. Likaså är det oklart om huvudets hållning vid sittandet och nackens funktion, exempelvis nackens rörelsefunktion och styrka, har betydelse för besvärsutveckling. Statiskt arbete med nacken i vridna och böjda positioner misstänks vara en riskfaktor för nack-skuldersmärta i yrken såsom tandläkare, men det är oklart varför vissa exponerade individer drabbas medan andra inte får ont. För de med långvarig smärta krävs ofta rehabiliterande åtgärder, och hur väl dessa åtgärder lyckas kan även det vara beroende av individens fysiska och psykosociala arbetsmiljö. Individens arbetsmiljö påverkar således inte bara risken för om man får besvär utan kan också ha betydelse för hur rehabiliteringen av besvären lyckas.

Syftet med detta symposium är att presentera studier från Centrum för belastningsskadeforskning som handlar om nacksmärta i arbetslivet, sammanfatta kunskapsläget inom området och diskutera hur arbetet kan utformas för att bli hållbart och inkluderande. De forskningsexempel som presenteras berör stillasittande och hållning i arbetslivet och dess tänkbara konsekvenser för nacksmärta och hälsa, riskfaktorer för nacksmärta i tandläkaryrket och arbetsmiljöns betydelse för resultatet av rehabilitering vid nacksmärta. Symposiet avslutas med en frågestund och gemensam diskussion.

Place, publisher, year, edition, pages
Gävle: Gävle University Press, 2018
National Category
Occupational Health and Environmental Health
Identifiers
urn:nbn:se:hig:diva-27196 (URN)978-91-88145-28-4 (ISBN)
Conference
FALF KONFERENS 2018 'Arbetet - problem eller potential för en hållbar livsmiljö?', 10-12 Juni 2018, Gävle
Funder
Forte, Swedish Research Council for Health, Working Life and WelfareAFA Insurance
Note

Symposiet omfattade följande presentationer:

1. Stillasittande och nackbesvär i yrken med manuellt arbete. David Hallman, Svend Erik Mathiassen, Marina Heiden, Marie Birk Jørgensen, Andreas Holtermann

2. Har personer med nacksmärta dålig hållning – kan detta vara av betydelse för besvärsutvecklingen? Thomas Rudolfsson, Martin Björklund, Åsa Svedmark, Mats Djupsjöbacka

3. Riskfaktorer bakom nacksmärta i tandläkaryrket. Fredrik Hellström, Tina Rönnlund Borg, Mats Djupsjöbacka, Martin Björklund

4. Påverkar arbetsmiljön rehabiliteringsresultatet? En longitudinell uppföljning av kvinnor med nacksmärta. Martin Björklund, Åsa Svedmark, Charlotte Häger, Johan Sommar, Jens Wahlström

Available from: 2018-06-20 Created: 2018-06-20 Last updated: 2018-12-17Bibliographically approved
Trask, C., Mathiassen, S. E., Wahlström, J. & Forsman, M. (2014). Cost-efficient assessment of biomechanical exposure in occupational groups, exemplified by posture observation and inclinometry. Scandinavian Journal of Work, Environment and Health, 40(3), 252-265
Open this publication in new window or tab >>Cost-efficient assessment of biomechanical exposure in occupational groups, exemplified by posture observation and inclinometry
2014 (English)In: Scandinavian Journal of Work, Environment and Health, ISSN 0355-3140, E-ISSN 1795-990X, Vol. 40, no 3, p. 252-265Article in journal (Refereed) Published
Abstract [en]

Objectives: This study compared the cost-efficiency of observation and inclinometer assessment of trunk and upper arm inclination in a population of flight baggage handlers, as an illustration of a general procedure for addressing the trade-off between resource consumption and statistical performance in occupational epidemiology.

Methods:  Trunk and upper arm inclination with respect to the line of gravity were assessed for 3 days on each of 27 airport baggage handlers using simultaneous recordings by inclinometers and video.  Labour and equipment costs associated with data collection and data processing were tracked throughout.  Statistical performance, in terms of the inverse of the standard deviation and root mean squared error of the group mean exposure, was computed from the variance components within and between workers, and bias (with inclinometer assumed to produce ‘correct’ inclination angles).  The behavior of the trade-off between cost and efficiency with changed sample size, as well as with changed logistics for data collection and processing, was investigated using simulations.

Results:  At similar total costs, time spent at trunk and arm inclination angles greater than 60 degrees as well as 90th percentile arm inclination were estimated at higher precision using inclinometers, while median inclination and 90th percentile trunk inclination was determined more precisely using observation.  This hierarchy persisted in a scenario where the study was immediately reproduced in another population, while inclinometry was more cost-efficient than observation for all three posture variables in a scenario where data were already collected and only needed to be processed. Observations showed to be biased relative to the –assumed to be correct – inclinometer data, and so inclinometry became the most cost-efficient option for all posture variables and irrespective of scenario when statistical performance was measured by bias and precision combined.

Conclusions: Inclinometers were more cost-efficient in use than observation for two out of three posture metrics investigated when statistical performance was measured only in terms of precision. Since observations were biased, inclinometers consistently outperformed observation when both bias and precision were included in statistical performance. The presented general model for assessing cost-efficiency may be used for designing exposure assessment strategies with considerations not only to statistical criteria, but even to costs. The empirical data provide a specific basis for planning assessments of working postures in occupational groups.

Keywords
Ergonomics, cost-efficiency, posture, shoulder, back, inclinometry, observation, questionnaire, work-related musculoskeletal disorders, baggage handling
National Category
Occupational Health and Environmental Health
Identifiers
urn:nbn:se:hig:diva-14743 (URN)10.5271/sjweh.3416 (DOI)000335288600006 ()2-s2.0-84899829766 (Scopus ID)
Funder
Forte, Swedish Research Council for Health, Working Life and WelfareAFA Insurance
Available from: 2013-06-25 Created: 2013-06-25 Last updated: 2018-03-13Bibliographically approved
Mathiassen, S. E., Liv, P. & Wahlström, J. (2013). Cost-efficient measurement strategies for posture observations based on video recordings. Applied Ergonomics, 44(4), 609-617
Open this publication in new window or tab >>Cost-efficient measurement strategies for posture observations based on video recordings
2013 (English)In: Applied Ergonomics, ISSN 0003-6870, E-ISSN 1872-9126, Vol. 44, no 4, p. 609-617Article in journal (Refereed) Published
Abstract [en]

Assessment of workingpostures by observation is a common practice in ergonomics. The present studyinvestigated whether monetary resources invested in a video-based posture observationstudy should preferably be spent in collecting many video recordings of thework and have them observed once by one observer, or in having multipleobservers rate postures repeatedly from fewer videos. The study addressed thisquestion from a practitioner’s perspective by focusing two plausible scenarios:documenting the mean exposure of one individual, and of a specific occupationalgroup. Using a data set of observed working postures among hairdressers, empiricalvalues of posture variability, observer variability, and costs for recordingand observing one video were entered into equations expressing the total costof data collection and the information (defined as 1/SD) provided by theresulting estimates of two variables: percentage time with the arm elevated<15 degrees and >90 degrees. Sixteen measurement strategies involving 1-4observers repeating their posture ratings 1-4 times were examined for budgetsup to €2000.  For both posture variablesand in both the individual and group scenario, the most cost-efficient strategyat any specific budget was to engage 3-4 observers and/or having observer(s)rate postures multiple times each. Between 17% and 34% less information wasproduced when using the commonly practiced approach of having one observer ratea number of video recordings one time each. We therefore recommend observationalposture assessment to be based on video recordings of work, since this allowsfor multiple observations; and to allocate monetary resources to repeated observationsrather than many video recordings.

Keywords
exposure assessment, research budget, resource consumption
National Category
Occupational Health and Environmental Health
Identifiers
urn:nbn:se:hig:diva-12511 (URN)10.1016/j.apergo.2012.12.003 (DOI)000317151100013 ()23333111 (PubMedID)2-s2.0-84875121958 (Scopus ID)
Available from: 2012-08-01 Created: 2012-08-01 Last updated: 2018-03-13Bibliographically approved
Trask, C., Mathiassen, S. E., Jackson, J. & Wahlström, J. (2013). Data processing costs for three posture assessment methods. BMC Medical Research Methodology, 13(1), 124
Open this publication in new window or tab >>Data processing costs for three posture assessment methods
2013 (English)In: BMC Medical Research Methodology, ISSN 1471-2288, E-ISSN 1471-2288, Vol. 13, no 1, p. 124-Article in journal (Refereed) Published
Abstract [en]

Objectives. Data processing contributes a non-trivial proportion to total research costs, but documentation of these costs is rare. This paper employed a priori cost tracking for three posture assessment methods (self-report, observation of video, and inclinometry), developed a model describing the fixed and variable cost components, and simulated additional study scenarios to demonstrate the utility of the model. 

Methods. Trunk and shoulder postures of aircraft baggage handlers were assessed for 80 working days using all three methods. A model was developed to estimate data processing phase costs, including fixed and variable components related to study planning and administration, custom software development, training of analysts, and processing time.   

Results. Observation of video was the most costly data processing method with total cost of 31,433, and was 1.2-fold more costly than inclinometry (€ 26,255), and 2.5-fold more costly than self-reported data (€ 12,491). Simulated scenarios showed altering design strategy could substantially impact processing costs. This was shown for both fixed parameters, such as software development and training costs, and variable parameters, such as the number of work-shift files processed, as well as the sampling frequency for video observation.  When data collection and data processing costs were combined, the cost difference between video and inclinometer methods was reduced to 7%; simulated data showed this difference could be diminished and, even, reversed at larger study sample sizes. Self-report remained substantially less costly under all design strategies, but produced alternate exposure metrics. 

Conclusions. These findings build on the previously published data collection phase cost model by reporting costs for post-collection data processing of the same data set.  Together, these models permit empirically based study planning and identification of cost-efficient study designs.

Keywords
cost-efficiency, shoulder, back, inclinometry, observation, questionnaire, work related musculoskeletal disorders, methods development
National Category
Occupational Health and Environmental Health
Identifiers
urn:nbn:se:hig:diva-13814 (URN)10.1186/1471-2288-13-124 (DOI)000329212500001 ()24118872 (PubMedID)2-s2.0-84885336051 (Scopus ID)
Funder
AFA Insurance, 100071Forte, Swedish Research Council for Health, Working Life and Welfare, Dnr 2009-1761
Available from: 2013-02-09 Created: 2013-02-09 Last updated: 2018-03-13Bibliographically approved
Mathiassen, S. E., Wahlström, J. & Forsman, M. (2012). Bias and imprecision in posture percentile variables estimated from short exposure samples. BMC Medical Research Methodology, 12, 36
Open this publication in new window or tab >>Bias and imprecision in posture percentile variables estimated from short exposure samples
2012 (English)In: BMC Medical Research Methodology, ISSN 1471-2288, E-ISSN 1471-2288, Vol. 12, p. 36-Article in journal (Refereed) Published
Abstract [en]

Background. Upper arm postures are believed to be an important risk determinant for musculoskeletal disorder development in the neck and shoulders. The 10th and 90th percentiles of the angular elevation distribution have been reported in many studies as measures of neutral and extreme postural exposures, and variation has been quantified by the 10th-90th percentile range. Further, the 50th percentile is commonly reported as a measure of "average" exposure. These four variables have been estimated using samples of observed or directly measured postures, typically using sampling durations between 5 and 120 min.

Methods. The present study examined the statistical properties of estimated full-shift values of the 10th, 50th and 90th percentile and the 10th-90th percentile range of right upper arm elevation obtained from samples of seven different durations, ranging from 5 to 240 min. The sampling strategies were realized by simulation, using a parent data set of 73 full-shift, continuous inclinometer recordings among hairdressers. For each shift, sampling duration and exposure variable, the mean, standard deviation and sample dispersion limits (2.5% and 97.5%) of all possible sample estimates obtained at one minute intervals were calculated and compared to the true full-shift exposure value.

Results. Estimates of the 10th percentile proved to be upward biased with limited sampling, and those of the 90th percentile and the percentile range, downward biased. The 50th percentile was also slightly upwards biased. For all variables, bias was more severe with shorter sampling durations, and it correlated significantly with the true full-shift value for the 10th and 90th percentiles and the percentile range. As expected, shorter samples led to decreased precision of the estimate; sample standard deviations correlated strongly with true full-shift exposure values.

Conclusions. The documented risk of pronounced bias and low precision of percentile estimates obtained from short posture samples presents a concern in ergonomics research and practice, and suggests that alternative, unbiased exposure variables should be considered if data collection resources are restricted.

National Category
Occupational Health and Environmental Health
Identifiers
urn:nbn:se:hig:diva-10941 (URN)10.1186/1471-2288-12-36 (DOI)000304421400001 ()22443348 (PubMedID)2-s2.0-84858736765 (Scopus ID)
Available from: 2011-11-28 Created: 2011-11-28 Last updated: 2018-03-13Bibliographically approved
Mathiassen, S. E., Liv, P. & Wahlström, J. (2012). Cost-efficient observation of working postures from video recordings – more videos, more observers or more views per observer?. Work: A journal of Prevention, Assesment and rehabilitation, 41(Suppl. 1), 2302-2306
Open this publication in new window or tab >>Cost-efficient observation of working postures from video recordings – more videos, more observers or more views per observer?
2012 (English)In: Work: A journal of Prevention, Assesment and rehabilitation, ISSN 1051-9815, E-ISSN 1875-9270, Vol. 41, no Suppl. 1, p. 2302-2306Article in journal (Refereed) Published
Abstract [en]

In ergonomics, assessing the working postures of an individual by observation is a very common practice. The present study investigated whether monetary resources devoted to an observational study should preferably be invested in collecting many video recordings of the work, or in having several observers estimate postures from available videos multiple times. On the basis of a data set of observed working postures among hairdressers, necessary information in terms of posture variability, observer variability, and costs for recording and observing videos was entered into equations providing the total cost of data collection and the precision (informative value) of the resulting estimates of two variables: percentages time with the arm elevated 90 degrees. In all 160 data collection strategies, differing with respect to the number of video recordings and the number of repeated observations of each recording, were simulated and compared for cost and precision. For both posture variables, the most cost-efficient strategy for a given budget was to engage 4 observers to look at available video recordings, rather than to have one observer look at more recordings. Since the latter strategy is the more common in ergonomics practice, we recommend reconsidering standard practice in observational posture assessment.

Keywords
resource consumption, mean exposure, risk assessment, posture observation, efficiency
National Category
Occupational Health and Environmental Health
Identifiers
urn:nbn:se:hig:diva-11553 (URN)10.3233/wor-2012-0456-2302 (DOI)000306361802071 ()2-s2.0-84859858198 (Scopus ID)
Available from: 2012-02-23 Created: 2012-02-23 Last updated: 2018-03-13Bibliographically approved
Trask, C., Mathiassen, S. E., Wahlström, J., Heiden, M. & Rezagholi, M. (2012). Data collection costs in industrial environments for three occupational posture exposure assessment methods. BMC Medical Research Methodology, 12, 89
Open this publication in new window or tab >>Data collection costs in industrial environments for three occupational posture exposure assessment methods
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2012 (English)In: BMC Medical Research Methodology, ISSN 1471-2288, E-ISSN 1471-2288, Vol. 12, p. 89-Article in journal (Refereed) Published
Abstract [en]

Background. Documentation of posture measurement costs is rare and cost models that do exist are generally naïve. This paper provides a comprehensive cost model for biomechanical exposure assessment in occupational studies, documents the monetary costs of three exposure assessment methods for different stakeholders in data collection, and uses simulations to evaluate the relative importance of cost components.  Trunk and shoulder posture variables were assessed for 27 aircraft baggage handlers for 3 full shifts each using three methods typical to ergonomic studies: self-report via questionnaire, observation via video film, and full-shift inclinometer registration.  The cost model accounted for expenses related to meetings to plan the study, administration, recruitment, equipment, training of data collectors, travel, and onsite data collection.  Sensitivity analyses were conducted using simulated study parameters and cost components to investigate the impact on total study cost.

Results. Inclinometery was the most expensive method (with a total study cost of € 66,657), followed by observation (€ 55,369) and then self report (€ 36,865). The majority of costs (90%) were borne by researchers.  Study design parameters such as sample size, measurement scheduling and spacing, concurrent measurements, location and travel, and equipment acquisition were shown to have wide-ranging impacts on costs. 

Conclusions. This study provided a general cost modelling approach that can facilitate decision making and planning of data collection in future studies, as well as investigation into cost efficiency and cost efficient study design. Empirical cost data from a large field study demonstrated the usefulness of the proposed models.

Keywords
Ergonomics, posture, inclinometer, observation, questionnaire
National Category
Occupational Health and Environmental Health
Identifiers
urn:nbn:se:hig:diva-10874 (URN)10.1186/1471-2288-12-89 (DOI)000308667100002 ()2-s2.0-84862751251 (Scopus ID)
Available from: 2011-11-15 Created: 2011-11-15 Last updated: 2018-03-13Bibliographically approved
Trask, C., Mathiassen, S. E., Wahlström, J., Heiden, M. & Rezagholi, M. (2012). Modeling costs of exposure assessment methods in industrial environments. Work: A journal of Prevention, Assesment and rehabilitation, 41, 6079-6086
Open this publication in new window or tab >>Modeling costs of exposure assessment methods in industrial environments
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2012 (English)In: Work: A journal of Prevention, Assesment and rehabilitation, ISSN 1051-9815, E-ISSN 1875-9270, Vol. 41, p. 6079-6086Article in journal (Refereed) Published
Abstract [en]

Documentation of posture measurement cost is rare and cost models that do exist are generally naïve. This paper provides a comprehensive cost model for ergonomic research, documents the monetary costs of three exposure assessment methods (inclinometry, video observation, and self-report), and discusses cost components. Trunk and shoulder posture were assessed for 27 aircraft baggage handlers for 3 full shifts each using three methods typical to ergonomics: self-report via questionnaire, observation via video film, and full-shift inclinometer registration. The model accounted for costs related to meetings to plan the study, administration, recruitment, equipment, training of data collectors, travel, and onsite data collection. Findings show that inclinometer was the most expensive method, followed by observation and then self report; the majority of costs (90%) were borne by researchers. Study design parameters such as sample size, measurement scheduling and spacing, concurrent measurements, location and travel, and equipment acquisition were shown to have wideranging impacts on costs. This study provided empirical cost data for use in cost models that can facilitate decision making and planning of future studies, and can be used to investigate cost efficiency in future studies

Keywords
cost efficiency, exposure assessment, work related musculoskeletal disorders, methods development
National Category
Occupational Health and Environmental Health
Identifiers
urn:nbn:se:hig:diva-11764 (URN)10.3233/WOR-2012-1064-6079 (DOI)000306361806045 ()2-s2.0-84859862402 (Scopus ID)
Available from: 2012-04-20 Created: 2012-04-20 Last updated: 2018-03-13Bibliographically approved
Wahlström, J., Mathiassen, S. E., Liv, P., Hedlund, P., Ahlgren, C. & Forsman, M. (2010). Upper arm postures and movements in female hairdressers across four full working days. Annals of Occupational Hygiene, 54(5), 584-594
Open this publication in new window or tab >>Upper arm postures and movements in female hairdressers across four full working days
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2010 (English)In: Annals of Occupational Hygiene, ISSN 0003-4878, E-ISSN 1475-3162, Vol. 54, no 5, p. 584-594Article in journal (Refereed) Published
Abstract [en]

OBJECTIVES: To describe upper arm postures and movements among female hairdressers, including the variability between hairdressers, between days within hairdresser, and between tasks, as a basis for understanding the characteristics of exposures in the job, considering possible sources of variation and recovery, and discussing appropriate exposure assessment strategies. METHODS: Data on upper arm postures were collected using inclinometers during four working days the same week from 28 female hairdressers working in 13 salons. Twenty of the hairdressers noted customer on and off times in a diary, to allow separate analyses of customer tasks (CT) and auxiliary non-customer tasks (AT), including breaks. For a number of posture and movement variables, mean values and variance components between subjects (BS) and within subjects between days (BD) were estimated using restricted maximum likelihood algorithms in one-way random effect models. RESULTS: For the 20 hairdressers with diaries, CT accounted for 279 min (58%) (SD(BS) = 39 min and SD(BD) = 85 min) of the working day and AT and breaks for 207 min (42%) (SD(BS) = 46 min and SD(BD) = 88 min). The hairdressers worked with the right arm elevated >60 degrees for 6.8% of the whole job (SD(BS) = 2.8% and SD(BD) = 2.0%). On average, the hairdressers worked with the right arm elevated >60 degrees for 9.0% of the time during CT, compared to 3.7% during AT, resulting in a contrast between tasks of 0.35. CONCLUSIONS: Hairdressers may be at risk for developing musculoskeletal disorders in the neck and shoulders due to a considerable occurrence of highly elevated arms, especially during CT. On the other hand, we do not find reasons to classify hairdressing as a job with too little variation. Posture variability between days within hairdressers was in the same order of magnitude as that between hairdressers, suggesting that 'typical' workdays do not exist. The exposure contrast between CT and AT for variables describing elevated arm postures indicates that for these variables a simple task-based approach for estimating job exposure could be successful.

Keywords
ergonomic epidemiology, exposure variability
National Category
Occupational Health and Environmental Health
Identifiers
urn:nbn:se:hig:diva-7330 (URN)10.1093/annhyg/meq028 (DOI)000280415100010 ()20385661 (PubMedID)2-s2.0-84929471282 (Scopus ID)1475-3162 (Electronic) 0003-4878 (Linking) (ISBN)
Available from: 2010-08-12 Created: 2010-08-12 Last updated: 2018-03-13Bibliographically approved
Liv, P., Mathiassen, S. E., Wahlström, J. & Hedlund, P. (2009). Between- and within-observer variability in two methods for posture observations. In: Proceedings of the IEA2009 conference. Paper presented at 17th Congress of the International Ergonomics Association (IEA), August 9-14, 2009, Beijing, China..
Open this publication in new window or tab >>Between- and within-observer variability in two methods for posture observations
2009 (English)In: Proceedings of the IEA2009 conference, 2009Conference paper, Published paper (Refereed)
Identifiers
urn:nbn:se:hig:diva-6367 (URN)
Conference
17th Congress of the International Ergonomics Association (IEA), August 9-14, 2009, Beijing, China.
Available from: 2010-02-11 Created: 2010-02-11 Last updated: 2018-03-13Bibliographically approved
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