| 1. |
- Wahlström, Jens, 1979-
(författare)
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Towards a simulation methodology for prediction of airborne wear particles from disc brakes
- 2009
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- During braking, both the rotor and the pads in disc brakes are worn. Since disc brakes are not sealed, some of the wear particles generated can become airborne. Several studies have found an association between adverse health effects and the concentration of particles in the atmosphere, so it is of interest to improve our knowledge of the airborne wear particles generated by disc brakes. However, in field tests it is difficult to distinguish these particles from others in the surrounding environment, so it may be preferable to use laboratory test stands and/or simulation models to study the amount of airborne wear particles generated. This thesis deals with a simulation methodology for prediction of airborne wear particles from disc brakes and three experimental methods for testing disc brake materials with focus on airborne wear particles. The four appended papers discuss the possibility to both measure and predict the number and size distribution of airborne wear particles that originate from the pad to rotor contact. The objective is to develop a simulation methodology that predicts the number and size distribution of airborne wear particles from disc brakes. Paper A describes how a modified pin-on-disc machine was used to study airborne wear particles originating from different disc brake materials. The results indicate that the test setup can be used to measure and rank the number concentration and size distribution of the airborne wear particles generated. Paper B describes a disc brake assembly test stand for measurements of airborne wear particles from disc brakes. The results indicate that the test setup can be used to measure the number concentration and size distribution of airborne wear particles generated from disc brake materials. The results also indicate a promising ability to rank different pad/rotor material combinations with respect to the number concentration of airborne wear particles. Paper C compares measurements made in passenger car field tests with measurements made in a disc brake assembly test stand and in a pin-on-disc machine. A promising correlation between the three different test methods is found. Paper D presents a simulation methodology for predicting the number and size distribution of airborne wear particles using finite element analysis (FEA). The simulated number distribution is compared with experimental measurements at component level. The result indicates that the proposed methodology may be used to predict the number concentration and size distribution of airborne particles generated in the pad-to-rotor contact.
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| 2. |
- Stjernbrandt, Albin, et al.
(författare)
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Occupational cold exposure and symptoms of carpal tunnel syndrome : a population-based study
- 2022
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Ingår i: BMC Musculoskeletal Disorders. - : BioMed Central. - 1471-2474. ; 23:1
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Cold exposure is an underrecognized occupational hazard that may increase the risk of peripheral nerve entrapment. The aim of this study was to determine if self-reported occupational exposure to contact and ambient cooling was associated with symptoms of carpal tunnel syndrome (CTS).METHODS: In this mainly cross-sectional study, surveys were conducted on a population-based sample of men and women between 18 and 70 years of age, living in northern Sweden. Cold exposure and presence of symptoms suggestive of CTS were subjectively reported. Associations between exposure and outcome were evaluated using logistic regression.RESULTS: The study included 2,703 women and 2,314 men, with a median age of 60 years (interquartile range 19). Symptoms of CTS were reported by 453 (9.2%). Being highly occupationally exposed (almost always) to contact cooling of the hands was associated with reporting CTS (OR 3.20; 95% CI 1.62-6.33), as was ambient cooling (OR 2.00; 95% CI 1.03-3.88) and severe ambient cooling (OR 4.02 95% CI 2.09-7.71), after adjusting for age, gender, body mass index, current daily smoking, diabetes mellitus, joint disease, and hand-arm vibration exposure. The point estimates increased with longer daily exposure duration. For workers exposed to severe ambient cooling for more than half of their working hours, in addition to performing heavy manual handling every day, the OR for reporting CTS was 7.25 (95% CI 3.88-13.53), with a positive additive interaction effect (expressed as relative excess risk due to interaction) of 4.67.CONCLUSIONS: Self-reported occupational exposure to contact and ambient cooling was associated with symptoms suggestive of CTS. There were statistically significant positive exposure-response patterns for time spent exposed to contact and ambient cooling at work in relation to reporting symptoms of CTS. Positive additive interaction effects between cold exposure and heavy manual handling were also found. Since there was important potential uncontrolled confounding regarding repetitive wrist movements and forceful gripping, the results need to be confirmed by other studies, preferably with longitudinal design and more detailed exposure assessment.
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| 3. |
- Stjernbrandt, Albin, et al.
(författare)
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Occupational cold exposure is associated with upper extremity pain
- 2023
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Ingår i: Frontiers in Pain Research. - : Frontiers Media S.A.. - 2673-561X. ; 4
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Tidskriftsartikel (refereegranskat)abstract
- Background: Occupational cold exposure is common in Sweden but potential impacts on musculoskeletal disorders have not been thoroughly investigated. The primary aim of this study was to determine the associations between occupational contact and ambient cooling in relation to pain in the upper extremity.Methods: In this cross-sectional study, a digital survey was conducted on a population-based sample of women and men between 24 and 76 years of age, living in northern Sweden. Occupational cold exposure, heavy manual handling, work with vibrating tools as well as the presence of upper extremity pain at different sites were subjectively reported. Associations between exposure and outcome were evaluated using multiple binary logistic regression.Results: The final study sample included 2,089 (54.4%) women and 1,754 men, with a mean age of 56 years. Hand pain was reported by 196 (5.2%), lower arm pain by 144 (3.8%), and upper arm pain by 451 (11.9%). Severe ambient cooling for more than half of the working time was statistically significantly associated with hand pain (OR: 2.30; 95% CI: 1.23–4.29) and upper arm pain (OR: 1.57; 95% CI: 1.00–2.47) but not lower arm pain (OR: 1.87; 95% CI: 0.96–3.65) after adjusting for gender, age, body mass index, current daily smoking, heavy manual handling, and work with vibrating tools.Conclusions: Occupational cold exposure was statistically significantly associated with hand pain and upper arm pain. Therefore, occupational cold exposure should be recognized as a potential risk factor for musculoskeletal disorders in the upper extremity.
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| 4. |
- Wahlström Edling, Cecilia, 1959-
(författare)
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Besvär i rörelseorganen hos musiklärare och deras syn på musikelevers hälsa : visioner och verklighet på kollisionskurs
- 2017
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The overall aim of the licentiate thesis was to reach a better understanding of music teachers' health, with focus on musculoskeletal disorders, and music teachers' view on young music students' health, from a gender perspective.A cross-sectional study was directed to music teachers employed at a municipality music- and culture school, in order to investigate the relationship between physical workload and work-related disorders among music teachers. Out of 61 music teachers 47 agreed to participate. The study group was divided into two groups depending on if they had an asymmetric or symmetric upper extremity and back playing posture. Musculoskeletal disorders were frequent among the music teachers. Women music teachers reported significantly more musculoskeletal disorders than their male collegues and music teachers with asymmetric work posture had significantly higher amount of musculoskeletal disorders than those who had a symmetric playing posture.A qualitative interview study with semi-structured interviews with 18 music teachers were conducted to explore music teachers' experiences of health and gender among young music students. An interview guide was used, with topic areas concerning experiences and perceptions of positive health aspects and health problems among young music students, taking part in music education. The interviews were analysed with qualitative content analysis according to Graneheim and Lundman. The analysis resulted in an overarching theme "Visions and reality in contradiction" and three categories: "Music making to feel good", "Pressure on girls, acceptance for boys" and "Blame on the individual".Music teachers at music- and culture schools seem to be at high risk of developing musculoskeletal disorders, especially music teachers playing an instrument that requires an asymmetric playing position. Young musicians' teachers need a better knowledge in the field of prevention of music students' health problems and physiotherapists and ergonomists may assist and collaborate in this. A gender perspective in music medicine research may contribute to a better understanding of musicians' health.
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| 5. |
- Abbasi, Saeed, et al.
(författare)
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A study of airborne wear particles generated from organic railway brake pads and brake discs
- 2011
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Ingår i: Wear. - UK : Elsevier. - 0043-1648 .- 1873-2577. ; 273:1, s. 93-99
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Tidskriftsartikel (refereegranskat)abstract
- Brake pads on wheel-mounted disc brakes are often used in rail transport due to their good thermal properties and robustness. During braking, both the disc and the pads are worn. This wear process generates particles that may become airborne and thus affect human health. The long term purpose of ‘Airborne particles in Rail transport’ project is to gain knowledge on the wear mechanisms in order to find means of controlling the number and size distribution of airborne particles. In this regard, a series of full-scale field tests and laboratory tests with a pin-on-disc machine have been conducted. The morphology and the matter of particles, along with their size distribution and concentration, have been studied. The validity of results from the pin-on-disc simulation has been verified by the field test results. Results show an ultra-fine peak for particles with a diameter size around 100 nm in diameter, a dominant fine peak for particles with a size of around 350 nm in diameter, and a coarse peak with a size of 3-7 μm in diameter. Materials such as iron, copper, aluminium, chromium, cobalt, antimony, and zinc have been detected in the nano-sized particles.
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| 6. |
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| 7. |
- Alemani, Mattia, et al.
(författare)
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ON THE INFLUENCE OF CAR BRAKE SYSTEM PARAMETERS ON PARTICULATE MATTER EMISSIONS
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The influence of car brake system parameters on particulate matter emissions was investigated using a pin-on-disc tribometer. Samples from a low-steel friction material and a cast iron disc were tested for different sliding velocities, nominal contact pressures and frictional powers. Disc temperatures were also measured. Their impact on total concentration, size distribution, particle coefficient and transition temperature was analysed. Results show that frictional power is the most significant brake system parameter. However, temperature, as a response parameter, is the most influential, inducing a shift towards the ultrafine particulate fraction and raising emissions. A transition temperature, independent of the system parameters, was identified.
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| 8. |
- Alemani, Mattia, et al.
(författare)
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On the influence of car brake system parameters on particulate matter emissions
- 2018
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Ingår i: Wear. - : ELSEVIER SCIENCE SA. - 0043-1648 .- 1873-2577. ; 396, s. 67-74
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Tidskriftsartikel (refereegranskat)abstract
- The influence of car brake system parameters on particulate matter emissions was investigated using a pin-on-disc tribometer. Samples from a low-steel friction material and a cast iron disc were tested for different sliding velocities, nominal contact pressures and frictional powers. Disc temperatures were also measured. Their impact on total concentration, size distribution, particle coefficient and transition temperature was analysed. Results show that frictional power is the most significant brake system parameter. However, temperature, as a response parameter, is the most influential, inducing a shift towards the ultrafine particulate fraction and raising emissions. A transition temperature, independent of the system parameters, was identified.
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| 9. |
- Alemani, Mattia
(författare)
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Particle emissions from car brakes : The influence of contact conditions on the pad-to-rotor interface
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Due to their adverse health effects emissions have been regulated for over three decades. Brake wear particulate matter is the most important non-exhaust source, however current knowledge is mainly limited to observational studies. This thesis aims to investigate relations between the brake system contact conditions and the related emissions on a model scale; validate the results on a component level; and understand to what extent they are significant on a full-scale.Paper A investigates the influence of nominal contact pressure on a model scale. Results show that higher pressure corresponds to higher emissionsPaper B investigates the influence of the nominal contact pressure, for different friction materials, on a model scale. A temperature threshold, responsible for a relevant emission increase, is identified.Paper C investigates particle characteristics and wear mechanisms for different nominal contact pressures, on a model scale. Results show an enhanced tribo-layer at higher pressure levels.Paper D investigates the influence of brake system conditions on emissions, on a model scale. Results show that frictional power is the most important parameter. A transition temperature independent of the contact condition is identified.Paper E investigates similarities occurring on a component scale and a model scale in terms of emissions. Results show a promising correlation, and the possibility of using a pin-on-disc tribometer for R&D activities.Paper F investigates analogies occurring on a component scale and a model scale, in terms of friction performance, fictional surface and chemical composition. Results show similar phenomena occurring for the two test stands.Paper G analyses real brake system working conditions in a urban environment defining, by means of an inertia dyno bench, the related emissions. Results reveal emission factors compliant to EURO6 and EURO2 regulations, in terms of number and mass, respectively.
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| 10. |
- Alemani, Mattia, et al.
(författare)
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Scaling effects of measuring disc brake airborne particulate matter emissions – A comparison of a pin-on-disc tribometer and an inertia dynamometer bench under dragging conditions
- 2018
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Ingår i: Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology. - : Sage Publications. - 1350-6501 .- 2041-305X. ; 232:12, s. 1538-1547
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Tidskriftsartikel (refereegranskat)abstract
- An important contributor to non-exhaust emissions in urban areas is airborne particulate matter originating from brake systems. A well-established way to test such systems in industry is to use inertia dynamometer benches; although they are quite expensive to run. Pin-on-disc tribometers, on the other hand, are relatively cheap to run, but simplify the real system. The literature indicates promising correlations between these two test stands with regard to measured airborne number distribution. Recent studies also show a strong dependency between the airborne number concentration and the disc temperature. However, a direct comparison that also takes into account temperature effects is missing. The aim of this paper is, therefore, to investigate how the transition temperature is affected by the different test scales, under dragging conditions, and the effects on total concentration and size distribution. New and used low-steel pins/pads were tested against cast iron discs/rotors on both the aforementioned test stands, appositely designed for particulate emission studies. A constant normal load and constant rotational velocity were imposed in both test stands. Results show that a transition temperature can always be identified. However, it is influenced by the test scale and the frictional pair status. Nevertheless, emissions are assessed similarly when an equivalent frictional pair status is analysed (e.g. run-in). Further investigations for fully run-in samples on the pin-on-disc should be performed in order to finally assess the possibility of using the tribometers for the initial assessment of different friction materials.
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| 11. |
- Athanassiou, N., et al.
(författare)
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Simulation of thermal and mechanical performance of laser cladded disc brake rotors
- 2022
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Ingår i: Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology. - London : SAGE Publications Ltd. - 1350-6501 .- 2041-305X. ; 236:1, s. 3-14
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Tidskriftsartikel (refereegranskat)abstract
- Disc brakes wear during braking events and release airborne particulates. These particle emissions are currently one of the highest contributors to non-exhaust particle emissions and introduce health hazards as well as environmental contamination. To reduce this problem, wear and corrosion-resistant disc coatings have been implemented on grey cast iron brake disc rotors by using various deposition techniques such as thermal spraying and overlay welding. High thermal gradients during braking introduce risks of flaking off and cracking of thermally sprayed coatings with adhesive bonding to the substrate. Overlay welding by laser cladding offers metallurgical bonding of the coating to the substrate and other benefits that motivate laser cladding as a candidate for the coating of the grey cast iron brake discs. This study aims to investigate the effect of laser cladding on the thermal and thermo-structural performance of the coated grey cast iron brake discs. Therefore, thermal and thermo-stress analysis with COMSOL Multiphysics 5.6 software is performed on braking events of grey cast iron brake discs as non-coated – reference and laser cladding coated with stainless steel welding consumables. The Results demonstrated that surface temperatures were more localised, overall higher in the laser cladded coating with over three times the stresses attained of reference grey cast iron discs. The output of the simulations has been compared by tests found in the literature. Laser cladding presented higher reliability and braking performance, nonetheless requiring the evaluation of its thermal impact on other system components.
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| 12. |
- Barker, Dean, 1977, et al.
(författare)
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Jacob and Martin: Developing digital technology competence in physical education teacher education
- 2016
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Ingår i: Digital Technologies and Learning in Physical Education. - Abingdon, Oxon ; New York, NY : Routledge, 2016. | : Routledge. - 9781315670164 - 9781138947283 - 9781138947290 ; , s. 231-246
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This chapter provides an illustration of how digital technologies (DTs) are experienced by Physical Education Teacher Education (PETE) students. The illustration is based on the reflections of two students at the University of Gothenburg, Sweden. The students received an assignment that involved demonstrating how a specific DT could be implemented. Three perspectives of the practitioners' experiences are provided. A Deweyan perspective shows how the students and their situations are transformed by DTs. A Foucauldian perspective focuses on the regulating aspects of technology. An applied Information Technology perspective demonstrates how DTs become part of the social practices of physical education. © 2017 Ashley Casey, Victoria A. Goodyear and Kathleen M. Armour. All rights reserved.
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| 13. |
- Björ, Bodil, et al.
(författare)
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Cold health impacts in northern Sweden
- 2016
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Ingår i: International Journal of Circumpolar Health. - : Informa UK Limited. - 1239-9736 .- 2242-3982. ; 75:33200
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Tidskriftsartikel (refereegranskat)
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| 14. |
- Björ, Ove, et al.
(författare)
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Reduced mortality rates in a cohort of long-term underground iron-ore miners
- 2013
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Ingår i: American Journal of Industrial Medicine. - : Wiley. - 0271-3586 .- 1097-0274. ; 56:5, s. 531-540
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Tidskriftsartikel (refereegranskat)abstract
- Background Historically, working in iron-ore mines has been associated with an increased risk of lung cancer and silicosis. However, studies on other causes of mortality are inconsistent and in the case of cancer incidence, sparse. The aim of this study was to examine the association between iron-ore mining, mortality and cancer incidence.Methods A 54-year cohort study on iron-ore miners from mines in northern Sweden was carried out comprising 13,000 workers. Standardized rate ratios were calculated comparing the disease frequency, mortality, and cancer incidence with that of the general population of northern Sweden. Poisson regression was used to evaluate the association between the durations of employment and underground work, and outcome.Results Underground mining was associated with a significant decrease in adjusted mortality rate ratios for cerebrovascular and digestive system diseases, and stroke. For several outcomes, elevated standardized rate ratios were observed among blue-collar workers relative to the reference population. However, only the incidence of lung cancer increased with employment time underground (P<0.001).Conclusions Long-term iron-ore mining underground was associated with lower rates regarding several health outcomes. This is possibly explained by factors related to actual job activities, environmental exposure, or the selection of healthier workers for long-term underground employment.Am. J. Ind. Med. 56:531540, 2013. (c) 2013 Wiley Periodicals, Inc.
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| 15. |
- Burström, Lage, et al.
(författare)
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A follow-up study of welders’ exposure to vibration in a heavy engineering production workshop
- 2010
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Ingår i: Journal of Low Frequency Noise Vibration and Active Control. - : Sage Publications. - 0263-0923 .- 1461-3484 .- 2048-4046. ; 29:1, s. 33-39
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Tidskriftsartikel (refereegranskat)abstract
- Manual work involving vibrating power tools is associated with symptoms that include vascular, neurological and musculoskeletal disorders. This study examines the vibration exposure of welders to determine the change between 1987 and 2008. Vibration measurements on handheld tools were used to evaluate the acceleration and the daily exposure time was determined by subjective rating. From these data, the 8-hour equivalent vibration exposure A(8), has been calculated. During the period, the A(8) decreased from 3.9 m/s2 to 1.9 m/s2. It was concluded that this decrease is the result of fewer vibrating tools and a decrease in daily exposure time. Although the daily vibration exposure has decreased over the study time, for some welders the daily vibration exposure A(8) is still above the action value set by the EU directive on vibration. This means more effort should be spent to decrease vibration exposure.
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| 16. |
- Burström, Lage, et al.
(författare)
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Back and neck pain due to working in a cold environment : a cross-sectional study of male construction workers
- 2013
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Ingår i: International Archives of Occupational and Environmental Health. - : Springer Science and Business Media LLC. - 0340-0131 .- 1432-1246. ; 86:7, s. 809-813
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To study whether work in a cold environment increased the risk of musculoskeletal symptoms in the neck and low back among construction workers. METHODS: This cross-sectional study is based on a cohort of male workers in the Swedish construction industry that participated in regular health examinations through a nationwide occupational health service. The analysis is based on workers examined from 1971 to 1974, who answered a questionnaire including questions about neck and back pain. The cohort consists of 134,754 male workers, including 16,496 office workers and foremen. The health examinations of the workers were conducted in provinces covering Sweden from the south to the north, and temperature data were collected for the provinces. In the analyses, the results were adjusted for age, BMI and use of nicotine. RESULTS: The prevalence's of neck and low back pain were higher among manual construction workers than among foremen and office workers (24.3 vs. 8.6 % and 16.5 vs. 6.2 %, respectively); the corresponding adjusted ORs for low back and neck pain were 1.59 (95 % CI 1.52-1.66) and 1.39 (95 % CI 1.30-1.49), respectively. Workers in the northern and central provinces had higher ORs for low back and neck pain compared to workers in the southern province. The test for trends showed an increased risk of developing low back and neck pain with decreased outdoor temperature. CONCLUSIONS: Outdoor work in a cold environment may increase the risk of low back and neck pain.
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| 17. |
- Burström, Lage, et al.
(författare)
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Daily text messages used as a method for assessing low back pain among workers
- 2016
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Ingår i: Journal of Clinical Epidemiology. - : Elsevier BV. - 0895-4356 .- 1878-5921. ; :70, s. 45-51
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: To evaluate a method for collecting data concerning low back pain (LBP) using daily text messages and to characterize the reported LBP in terms of intensity, variability, and episodes.STUDY DESIGN AND SETTING: We conducted a cohort study of LBP among workers used by a mining company. The participants were asked to answer the question "How much pain have you had in your lower back in the last 24 hours on a scale from 0 to 10, where 0 = no pain and 10 = the worst pain imaginable" once a day for 5 weeks, with this process being repeated 6 months later.RESULTS: A total of 121 workers participated in the first period of data collection, and 108 participated in the second period. The daily response rate was 93% for both periods, and cluster analysis was shown to be a feasible statistical method for clustering LBP into subgroups of low, medium, and high pain. The daily text messages method also worked well for assessing the episodic nature of LBP.CONCLUSION: We have demonstrated a method for repeatedly measuring of LBP using daily text messages. The data permitted clustering into subgroups and could be used to define episodes of LBP.
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| 18. |
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| 19. |
- Burström, Lage, et al.
(författare)
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Musculoskeletal symptoms and exposure to whole-body vibration among open-pit mine workers in the arctic
- 2017
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Ingår i: International Journal of Occupational Medicine and Environmental Health. - : Nofer Institute of Occupational Medicine. - 1232-1087 .- 1896-494X. ; 30:4, s. 553-564
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: This cross-sectional questionnaire study was carried out at 4 open-pit mines in Finland, Norway, Russia and Sweden as part of the MineHealth project. The aim has been to compare the prevalence of musculoskeletal symptoms between drivers of mining vehicles and non-drivers. Material and Methods: The mine workers were asked whether they had suffered from any musculoskeletal symptoms during the previous 12 months in specified body regions, and to grade the severity of these symptoms during the past month. They were also asked about their daily driving of mining vehicles. Results: The questionnaire was completed by 1323 workers (757 vehicle drivers) and the reported prevalence and severity of symptoms were highest for the lower back, followed by pain in the neck, shoulder and upper back. Drivers in the Nordic mines reported fewer symptoms than non-drivers, while for Russian mine workers the results were the opposite of that. The daily driving of mining vehicles had no significant association with the risk of symptoms. Female drivers indicated a higher prevalence of symptoms as compared to male drivers. Conclusions: The study provided only weak support for the hypothesis that drivers of vehicles reported a higher prevalence of musculoskeletal symptoms than non-vehicle drivers. There were marked differences in the prevalence of symptoms among workers in various enterprises, even though the nature of the job tasks was similar.
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| 20. |
- Burström, Lage, et al.
(författare)
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Thermal perception thresholds among workers in a cold climate
- 2017
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Ingår i: International Archives of Occupational and Environmental Health. - : Springer. - 0340-0131 .- 1432-1246. ; 90:7, s. 645-652
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To investigate whether exposure to cold could influence the thermal perception thresholds in a working population.METHODS: This cross-sectional study was comprised of 251 males and females and was carried out at two mines in the northern part of Norway and Sweden. The testing included a baseline questionnaire, a clinical examination and measurements of thermal perception thresholds, on both hands, the index (Digit 2) and little (Digit 5) fingers, for heat and cold.RESULTS: The thermal perception thresholds were affected by age, gender and test site. The thresholds were impaired by experiences of frostbite in the fingers and the use of medication that potentially could affect neurosensory functions. No differences were found between the calculated normative values for these workers and those in other comparative investigations conducted in warmer climates.CONCLUSIONS: The study provided no support for the hypothesis that living and working in cold climate will lead to impaired thermal perception thresholds. Exposure to cold that had caused localized damage in the form of frostbite was shown to lead to impaired thermal perception.
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| 21. |
- Burström, Lage, 1954-, et al.
(författare)
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White fingers, cold environment, and vibration : exposure among Swedish construction workers
- 2010
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Ingår i: Scandinavian Journal of Work, Environment and Health. - : Scandinavian Journal of Work, Environment and Health. - 0355-3140 .- 1795-990X. ; 36:6, s. 509-513
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Tidskriftsartikel (refereegranskat)abstract
- Objectives The aim of this study was to examine the association between white fingers, cold environment, and exposure to hand–arm vibration (HAV). The hypothesis was that working in cold climate increases the risk of white fingers.Methods The occurrence of white fingers was investigated as a cross-sectional study in a cohort of Swedish male construction workers (N=134 757). Exposure to HAV was based on a job-exposure matrix. Living in the north or south of Sweden was, in a subgroup of the cohort, used as an indicator of the exposure to cold environment (ie, living in the north meant a higher exposure to cold climate). The analyses were adjusted for age and use of nicotine products (smoking and snuff).Results HAV-exposed workers living in a colder climate had a higher risk for white fingers than those living in a warmer climate [odds ratio (OR) 1.71, 95% confidence interval (95% CI) 1.42–2.06]. As expected, we found that HAV-exposed workers had an increased risk compared to controls (OR 2.02, 95% CI 1.75–2.34). The risk for white fingers increased with increased level of exposure to HAV and also age.Conclusions Cold environment increases the risk for white fingers in workers occupationally exposed to HAV. The results underscore the need to keep exposure to HAV at workplaces as low as possible especially in cold climate.
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| 22. |
- Burström, Lage, et al.
(författare)
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Whole-body vibration and the risk of low back pain and sciatica : a systematic review and meta-analysis
- 2015
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Ingår i: International Archives of Occupational and Environmental Health. - : Springer Science and Business Media LLC. - 0340-0131 .- 1432-1246. ; 88:4, s. 403-418
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: The aim of this systematic literature review was to evaluate the association between whole-body vibration (WBV) and low back pain (LBP) and sciatica with special attention given to exposure estimates. Moreover, the aim was to estimate the magnitude of such an association using meta-analysis and to compare our findings with previous reviews.METHODS: The authors systematically searched the PubMed (National Library of Medicine, Bethesda), Nioshtic2 (National Institute for Occupational Safety and Health (NIOSH, Morgantown), and ScienceDirect (Elsevier, Amsterdam) databases for records up to December 31, 2013. Two of the authors independently assessed studies to determine their eligibility, validity, and possible risk of bias.RESULTS: The literature search gave a total of 306 references out of which 28 studies were reviewed and 20 were included in the meta-analysis. Exposure to WBV was associated with increased prevalence of LBP and sciatica [pooled odds ratio (OR) = 2.17, 95 % confidence interval (CI) 1.61-2.91 and OR 1.92, 95 % CI 1.38-2.67, respectively]. Workers exposed to high vibration levels had a pooled risk estimate of 1.5 for both outcomes when compared with workers exposed to low levels of vibration. The results also indicate that some publication bias could have occurred especially for sciatica.CONCLUSIONS: This review shows that there is scientific evidence that exposure to WBV increases the risk of LBP and sciatica.
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| 23. |
- Carlsson, Daniel, 1982-, et al.
(författare)
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Can sensation of cold hands predict Raynaud's phenomenon or paraesthesia?
- 2018
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Ingår i: Occupational Medicine. - : Oxford University Press (OUP). - 0962-7480 .- 1471-8405. ; 68:5, s. 314-319
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Tidskriftsartikel (refereegranskat)abstract
- Background Raynaud's phenomenon and neurosensory symptoms are common after hand-arm vibration exposure. Knowledge of early signs of vibration injuries is needed. Aims To investigate the risk of developing Raynaud's phenomenon and paraesthesia in relation to sensation of cold hands in a cohort of male employees at an engineering plant. Methods We followed a cohort of male manual and office workers at an engineering plant in Sweden for 21 years. At baseline (1987 and 1992) and each follow-up (1992, 1997, 2002, 2008), we assessed sensation of cold, Raynaud's phenomenon and paraesthesia in the hands using questionnaires and measured vibration exposure. We calculated risk estimates with univariate and multiple logistic regression analyses and adjusted for vibration exposure and tobacco usage. Results There were 241 study participants. During the study period, 21 individuals developed Raynaud's phenomenon and 43 developed paraesthesia. When adjusting the risk of developing Raynaud's phenomenon for vibration exposure and tobacco use, the odds ratios were between 6.0 and 6.3 (95% CI 2.2-17.0). We observed no increased risk for paraesthesia in relation to a sensation of cold hands. Conclusions A sensation of cold hands was a risk factor for Raynaud's phenomenon. At the individual level, reporting a sensation of cold hands did not appear to be useful information to predict future development of Raynaud's phenomenon given a weak to moderate predictive value. For paraesthesia, the sensation of cold was not a risk factor and there was no predictive value at the individual level.
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| 24. |
- Carlsson, Daniel, 1982-
(författare)
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Effects of cold and hand-arm vibration on the peripheral neurosensory and vascular system : an occupational perspective
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background In Swedish working life, exposure to cold and exposure to hand-arm vibration (HAV) are two common health hazards. Health effects of HAV in the neurosensory, vascular and musculoskeletal systems are collectively denoted hand-arm vibration syndrome (HAVS), and have been thoroughly studied. Effects of cold exposure in terms of effects on the peripheral neurosensory and vascular system are on the contrary limited, especially in an occupational setting. Effects of cold exposure or cold injury have not previously been assessed with quantitative sensory testing (QST). Commonly reported symptoms after exposure to HAV and after cold injuries, includes cold sensitivity and sensation of cold. Cold sensitivity can also occur without previous exposure to vibration or cold and may have a major impact on quality of life. Other possible risk factors for cold sensitivity need to be assessed. Sensation of cold hands could theoretically imply an early manifestation of damage to the neurosensory or vascular system, and therefore be of importance to enable early detection of vascular and neurosensory HAVS. The purpose of this thesis was to increase the knowledge about health effects from cold and HAV on the peripheral neurosensory and vascular system, with an occupational perspective. The aims were: first, to identify and evaluate health effects and sequelae in the peripheral neurosensory and vascular system due to cold injury and cold exposure; second, to investigate if sensation of cold hands is a predictor for future onset of Raynaud's phenomenon or paresthesia; and third, to identify possible risk factors associated with cold sensitivity.Methods A case series on 15 military conscripts with local cold injuries in the hands or feet, involving QST and symptom descriptions, was conducted to investigate the hypothesis that cold injuries can result in similar neurosensory and vascular impairments as in HAVS. To assess health effects of cold exposure, a cohort study on 54 military conscripts in cold winter military training, with cold exposure assessments, was conducted. Possible health effects were assessed after 14 months of military training, containing considerable cold exposure, by means of QST, Finger systolic blood pressure after local cooling (FSBP) and a questionnaire. To investigate if sensation of cold hands is a predictor for vascular or neurosensory HAVS we investigated a cohort of 178 employees at a manufacturing company where HAV was a common exposure. The cohort was followed during 21 years and both vibration exposure and health outcomes were assessed regularly. Questionnaire items were used to assess sensations of cold hands as well as signs of Raynaud’s phenomenon and paresthesia. To identify risk factors for cold sensitivity a case-control study was conducted involving 997iiiparticipants from the general population in northern Sweden. The study was cross-sectional and explored possible risk factors for cold sensitivity.Results Cold injuries and cold exposure were associated with reduced sensibility in QST and increase severity and prevalence of neurosensory and vascular symptoms. Our results did not show any impairment in peripheral blood flow due to cold exposure, detectable by FSBP. The risk of developing Raynaud's phenomenon was increased for workers previously reporting sensation of cold hands (OR 6.3, 95% CI 2.3-17.0). No increased risk for paresthesia in relation to a sensation of cold hands was observed. The identified risk factors for cold sensitivity were frostbite in the hands, rheumatic disease, nerve injury in upper extremities or neck, migraine and vascular disease. When analysing women and men separately, women’s risk factors were frostbite in the hands, rheumatic disease, migraine and cold exposure. Men’s risk factors were frostbite in the hands, vibration exposure and nerve injury in upper extremities or neck. BMI > 25 was a protective factor for both men and women.Conclusion Cold injury and cold exposure are associated with impairments in the neurosensory system, detectable by QST. Symptoms such as sensation of cold hands and white fingers indicate vascular involvement, even though no vascular impairments due to cold exposure could be detected by objective measurements. A sensation of cold hands is a risk factor for development of Raynaud´s phenomenon, but not for paresthesia. At the individual level, reporting cold hands does not appear to be useful information when considering the possibility of a future development of Raynaud’s phenomenon. Frostbite in the hands is a risk factor for cold sensitivity among both women and men. For women rheumatic disease, migraine and cold exposure are also independent risk factors, and for men, exposure to HAV. Being overweight is a protective factor for both women and men.
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| 25. |
- Carlsson, Daniel, et al.
(författare)
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Neurosensory and vascular function after 14 months of military training comprising cold winter conditions
- 2016
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Ingår i: Scandinavian Journal of Work, Environment and Health. - : Scandinavian journal of work, environment & health. - 0355-3140 .- 1795-990X. ; 42:1, s. 61-70
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: This study aimed to examine the effects of 14 months of military training comprising cold winter conditions on neurosensory and vascular function in the hands and feet.METHODS: Military conscripts (N=54) were assessed with quantitative sensory testing comprising touch, temperature, and vibration perception thresholds and finger systolic blood pressure (FSBP) after local cooling and a questionnaire on neurosensory and vascular symptoms at both baseline and follow-up. Ambient air temperature was recorded with body worn temperature loggers.RESULTS: The subjects showed reduced sensitivity to perception of touch, warmth, cold and vibrations in both the hands and feet except from vibrotactile perception in digit two of the right hand (right dig 2). Cold sensations, white fingers, and pain/discomfort when exposed to cold as well as pain increased in both prevalence and severity. There were no statistically significant changes in FSBP after local cooling.CONCLUSION: Fourteen months of winter military training comprising cold winter conditions reduced sensation from touch, warmth, cold, and vibrotactile stimulus in both hands and feet and increased the severity and prevalence of symptoms and pain. The vascular function in the hands, measured by FSBP after local cooling, was not affected.
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| 26. |
- Carlsson, Daniel, et al.
(författare)
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Neurosensory sequelae assessed by thermal and vibrotactile perception thresholds after local cold injury
- 2014
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Ingår i: International Journal of Circumpolar Health. - : Informa UK Limited. - 1239-9736 .- 2242-3982. ; 73
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Tidskriftsartikel (refereegranskat)abstract
- Background. Local freezing cold injuries are common in the north and sequelae to cold injury can persist many years. Quantitative sensory testing (QST) can be used to assess neurosensory symptoms but has previously not been used on cold injury patients.Objective. To evaluate neurosensory sequelae after local freezing cold injury by thermal and vibrotactile perception thresholds and by symptom descriptions.Design. Fifteen patients with a local freezing cold injury in the hands or feet, acquired during military training, were studied with QST by assessment of vibrotactile (VPT), warmth (WPT) and cold (CPT) perception thresholds 4 months post-injury. In addition, a follow-up questionnaire, focusing on neurovascular symptoms, was completed 4 months and 4 years post-injury.Results. QST demonstrated abnormal findings in one or both affected hands for VPT in 6 patients, for WPT in 4 patients and for CPT in 1 patient. In the feet, QST was abnormal for VPT in one or both affected feet in 8 patients, for WPT in 6 patients and for CPT in 4 patients. Freezing cold injury related symptoms, e. g. pain/discomfort when exposed to cold, cold sensation and white fingers were common at 4 months and persisted 4 years after the initial injury.Conclusions. Neurosensory sequelae after local freezing cold injury, in terms of abnormal thermal and/or vibration perception thresholds, may last at least 4 months after the initial injury. Symptoms such as pain/discomfort at cold exposure, cold sensations and white fingers may persist at least 4 years after the initial injury.
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| 27. |
- da Silva, Marisa, et al.
(författare)
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Cohort profile : The Obesity and Disease Development Sweden (ODDS) study, a pooled cohort
- 2024
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Ingår i: BMJ Open. - 2044-6055. ; 14:7
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: The Obesity and Disease Development Sweden (ODDS) study was designed to create a large cohort to study body mass index (BMI), waist circumference (WC) and changes in weight and WC, in relation to morbidity and mortality.PARTICIPANTS: ODDS includes 4 295 859 individuals, 2 165 048 men and 2 130 811 women, in Swedish cohorts and national registers with information on weight assessed once (2 555 098 individuals) or more (1 740 761 individuals), in total constituting 7 733 901 weight assessments at the age of 17-103 years in 1963-2020 (recalled weight as of 1911). Information on WC is available in 152 089 men and 212 658 women, out of whom 108 795 have repeated information on WC (in total 512 273 assessments). Information on morbidity and mortality was retrieved from national registers, with follow-up until the end of 2019-2021, varying between the registers.FINDINGS TO DATE: Among all weight assessments (of which 85% are objectively measured), the median year, age and BMI (IQR) is 1985 (1977-1994) in men and 2001 (1991-2010) in women, age 19 (18-40) years in men and 30 (26-36) years in women and BMI 22.9 (20.9-25.4) kg/m 2 in men and 23.2 (21.2-26.1) kg/m 2 in women. Normal weight (BMI 18.5-24.9 kg/m 2) is present in 67% of assessments in men and 64% in women and obesity (BMI≥30 kg/m 2) in 5% of assessments in men and 10% in women. The median (IQR) follow-up time from the first objectively measured or self-reported current weight assessment until emigration, death or end of follow-up is 31.4 (21.8-40.8) years in men and 19.6 (9.3-29.0) years in women. During follow-up, 283 244 men and 123 457 women died. FUTURE PLANS: The large sample size and long follow-up of the ODDS Study will provide robust results on anthropometric measures in relation to risk of common diseases and causes of deaths, and novel findings in subgroups and rarer outcomes.
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| 28. |
- Eklöf, Mats, et al.
(författare)
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Workplace intervention for improved risk perception and preventive activity among workers : using hand-held vibrating machines: a pilot study
- 2023
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This article presents a pilot study of a 1-h workplace educational intervention implemented among ten construction workers who were highly exposed to hand–arm vibration. The intervention combined risk communication and normative expert advice intended to reinforce preventive behaviour related to vibration, noise, and biomechanical loads. Data for this study comprised intervention notes and interview data from interventionists, and pre- and post-intervention interview data from participating workers.The results suggested that the intervention was sensitive to disturbances and should be directed only to motivated workers possessing sufficient self-efficacy, and only in circumstances in which exposure may be controlled on the local workplace level and by locally implemented measures. Unless these conditions are present, the studied intervention may fail to influence preventive behaviour, and may instead cause cognitive dissonance and frustration among participants and interventionists.
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| 29. |
- Eliasson, Kristina, 1979-
(författare)
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Occupational health services in the prevention of musculoskeletal disorders : Processes, tools and organizational aspects
- 2017
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Work-related musculoskeletal disorders are associated with high costs and it is essential to prevent them. Occupational Health Services(OHS) provide expert services regarding work environment, health and rehabilitation of work related disorders. Risk assessments of the work environment can be an initial step for preventive measures, and ergonomists can be assigned by clients to assess exposures in the work environment. For such assignments different tools can be used. The aim of this thesis was to explore prerequisites, processes and practices of OHS consultants in Sweden within the domain of primary prevention of work-related musculoskeletal disorders. This was explored through the work of ergonomists in their role of assessing ergonomics risks. The research methodology was both quantitative and qualitative. Data collection includes a web questionnaire, semi-structured interviews and inter- and intra-observer reliability tests. The results shows that ergonomics risk assessments were most commonly initiated reactively and a systematic work methodology for the risk assessment process was often lacking. Swedish ergonomists used only a few standardized tools for risk assessment. The Ergonomics provision from the Swedish Work Environment Authority, AFS-98, was widely used, but other observation-based tools were used far less often. Ergonomics risks were often assessed solely by means of observation, based on ergonomists’ knowledge and experience. The results also pointed to that that the reliability was not acceptable when risk assessment was performed without any standardized tool. Furthermore, the results point to that support from the OHS organizations is an important prerequisite for ergonomists to work with primary prevention. Further, opportunities for specialization within a specific industry sector seem to facilitate ergonomic interventions. It is also important to have close relationships with clients and to make them aware about ergonomists competence. Conclusively, this thesis identifies a numbers of areas in which OHS must develop to improve primary preventive services regarding work environment.
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| 30. |
- Ericsson, Pernilla, et al.
(författare)
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Exposure assessment in different occupational groups at a hospital using Quick Exposure Check (QEC) : A pilot study
- 2012
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Ingår i: Work. - 1051-9815 .- 1875-9270. ; 41:Supplement 1, s. 5718-5720
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Tidskriftsartikel (refereegranskat)abstract
- In order to test the feasibility and sensitivity of the ergonomic exposure assessment tool Quick Exposure Check (QEC), a pilot-study was conducted. The aim was to test QEC in different occupational groups to compare the exposure in the most common work task with the exposure in the work task perceived as the most strenuous for the neck/shoulder region, and to test intra-observer reliability. One experienced ergonomist observed 23 workers. The mean observation time was 45 minutes, waiting time and time for complementary questions included. The exposure scores varied between the different occupational groups as well as between workers within the occupational groups. Eighteen workers rated their most common work task as also being the most strenuous for the neck/shoulder region. For the remaining five workers, the mean exposure score were higher both for the neck and shoulder/arm in the most common work task. Intra-observer reliability shows agreement in 86% of the exposure interactions in the neck and in 71% in the shoulder/arm. QEC seems to fulfill the expectations of being a quick, sensible and practical exposure assessment tool that covers physical risk factors in the neck, upper extremities and low back.
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| 31. |
- Ericsson, Pernilla, et al.
(författare)
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Reliability testing of two ergonomic risk assessment tools
- 2012
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- INTRODUCTIONQuick Exposure Check (QEC¹) and Rapid Upper Limb Assessment (RULA²) are two ergonomic risk assessment tools that have been designed to be useful for ergonomists assessing musculoskeletal risk factors in upper extremities at workplaces.AIMThe aim was to describe the variation between and within ergonomists assessments using QEC and RULA, and to compare the two tools regarding within-observer agreement.SUBJECTS & METHODSTwenty ergonomists observed five different work tasks twice with three weeks in between, watching video clips. They made ergonomic risk assessments using both QEC and RULA.The observed work tasks were: Window replacement, nailing a wooden pallet, toilet cleaning, instrumentation in an operating theatre, and sorting post.For the statistical analyses, percent agreement and kappa value was used.RESULTSThere was a variation in assessments between the ergonomists in all positions and movements both when using QEC and RULA, except from assessing armposition when observing window replacement using QEC, where all ergonomists assessed the same position (figure 1).The ergonomists had higher percent agreement between observation one and two using QEC compared with RULA (table 1).CONCLUSIONThere was a variation when assessing positions and movements in different worktasks both between ergonomists and within the same ergonomist using both QEC and RULA. However the agreement between two observations within observers was higher for QEC.
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| 32. |
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| 33. |
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| 34. |
- Fullagar, Wilfred, et al.
(författare)
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A broadband laser plasma X-ray source for application in ultrafast chemical structure dynamics
- 2007
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 1089-7623 .- 0034-6748. ; 78:11, s. 1-115105
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Tidskriftsartikel (refereegranskat)abstract
- A plasma source free from characteristic emission lines is described, based on laser irradiation of a water jet in a helium atmosphere. Various key aspects of the laser interaction are presented along with practical characterization of the observed isotropic ~4–10 keV x-ray emissions, measurements of which indicate subpicosecond duration. Observations are consistent with a vacuum heating plasma mechanism at the helium-water interface and indicate strong potential for in-house ultrafast chemical structure dynamics application when coupled to contemporary detector developments.
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| 35. |
- Fullagar, Wilfred, et al.
(författare)
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Lab-based Ultrafast Molecular Structure.
- 2010
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Ingår i: AIP Conference Proceedings. - : AIP. - 1551-7616 .- 0094-243X. ; 1234, s. 919-922
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Konferensbidrag (refereegranskat)abstract
- The proliferation of various laser-driven approaches to sub-picosecond hard X-ray and short-wavelength radiation generation in the past few decades has opened many avenues for the laboratory-based development of traditionally facility-based short wavelength ultrafast molecular structure science. Together with the introduction of microcalorimeter detection schemes, this opens the floodgates to widespread, decentralized implementation of what were until recently specialist short wavelength techniques. A parallel situation exists for the contemporary adoption of sub-wavelength resolution optical microscopies. In what follows, a few ultrafast molecular structure developments and their rationale are briefly recounted.
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| 36. |
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| 37. |
- Fyhr, Pontus, et al.
(författare)
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An Experimental Study of Forced Vibration Influence on Disc Brake Drag Torque in Heavy Commercial Road Vehicles
- 2022
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Ingår i: Tribology in Industry. - : Faculty of Engineering, University of Kragujevac. - 0354-8996 .- 2217-7965. ; 44:1, s. 123-131
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Tidskriftsartikel (refereegranskat)abstract
- Drag torque in a disc brake is the residual torque when the brake is not activated. This torque can adversely influence the total energy consumption, life of the brake components, and level of airborne wear particles from vehicles. Drag torque is of special interest for long haul trucking since it could have an effect of the total energy consumption. Drag torque performance of a disc brake is usually evaluated with conventional inertia dynamometers. Vibrations induced by the wheel can help to retract the pads from the disc and decrease the drag torque. It is hard to study this phenomenon with conventional inertia dynamometers since there is usually no system to induce a forced vibration on the brake. Therefore, the aim of the paper is to investigate the effect of vibrations on the drag torque for a commercial vehicle disc brake with a novel test setup. This is done by comparing test run with and without pads, forced vibrations, and pad retraction springs. The results indicate that the forced vibrations strongly affect the level of measured drag torque. In addition, the introduction of a retraction spring can reduce drag torque with more than 50% when vibrations are induced.
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| 38. |
- Genoud, Guillaume, et al.
(författare)
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Laser-plasma electron acceleration in dielectric capillary tubes
- 2011
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Ingår i: Applied Physics B. - : Springer Science and Business Media LLC. - 0946-2171 .- 1432-0649. ; 105:2, s. 309-316
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Tidskriftsartikel (refereegranskat)abstract
- Electron beams and betatron X-ray radiation generated by laser wakefield acceleration in long plasma targets are studied. The targets consist of hydrogen filled dielectric capillary tubes of diameter 150 to 200 microns and length 6 to 20 mm. Electron beams are observed for peak laser intensities as low as 5x10(17) W/cm(2). It is found that the capillary collects energy outside the main peak of the focal spot and contributes to keep the beam self-focused over a distance longer than in a gas jet of similar density. This enables the pulse to evolve enough to reach the threshold for wavebreaking, and thus trap and accelerate electrons. No electrons were observed for capillaries of large diameter (250 mu m), confirming that the capillary influences the interaction and does not have the same behaviour as a gas cell. Finally, X-rays are used as a diagnostic of the interaction and, in particular, to estimate the position of the electrons trapping point inside the capillary.
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| 39. |
- Ghalebani, Leila, et al.
(författare)
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pH-dependence of the specific binding of Cu(II) and Zn(II) ions to the amyloid-beta peptide
- 2012
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Ingår i: Biochemical and Biophysical Research Communications - BBRC. - : Elsevier BV. - 0006-291X .- 1090-2104. ; 421:3, s. 554-560
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Tidskriftsartikel (refereegranskat)abstract
- Metal ions like Cu(II) and Zn(II) are accumulated in Alzheimer's disease amyloid plaques. The amyloid-beta (A beta) peptide involved in the disease interacts with these metal ions at neutral pH via ligands provided by the N-terminal histidines and the N-terminus. The present study uses high-resolution NMR spectroscopy to monitor the residue-specific interactions of Cu(II) and Zn(II) with N-15- and C-13,N-15-labeled A beta(1-40) peptides at varying pH levels. At pH 7.4 both ions bind to the specific ligands, competing with one another. At pH 5.5 Cu(II) retains its specific histidine ligands, while Zn(II) seems to lack residue-specific interactions. The low pH mimics acidosis which is linked to inflammatory processes in vivo. The results suggest that the cell toxic effects of redox active Cu(II) binding to AD may be reversed by the protective activity of non-redox active Zn(II) binding to the same major binding site under non-acidic conditions. Under acidic conditions, the protective effect of Zn(II) may be decreased or changed, since Zn(II) is less able to compete with Cu(II) for the specific binding site on the AD peptide under these conditions.
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| 40. |
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| 41. |
- Hallman, David, 1979-, et al.
(författare)
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Symposium: Arbete, individ och nacksmärta : Forskning vid Forte-centret “Kroppen i arbete – från problem till potential”
- 2018
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Ingår i: FALF KONFERENS 2018 Arbetet - problem eller potential för en hållbar livsmiljö? 10-12 juni 2018 i Gävle. - Gävle : Gävle University Press. - 9789188145284 ; , s. 102-
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Konferensbidrag (refereegranskat)abstract
- 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.
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| 42. |
- Heiden, Marina, et al.
(författare)
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A comparison of two strategies for building an exposure prediction model
- 2016
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Ingår i: Annals of Occupational Hygiene. - : Oxford University Press (OUP). - 0003-4878 .- 1475-3162. ; 60:1, s. 74-89
-
Tidskriftsartikel (refereegranskat)abstract
- Cost-efficient assessments of job exposures in large populations may be obtained from models in which “true” exposures assessed by expensive measurement methods are estimated from easily accessible and cheap predictors. Typically, the models are built on the basis of a validation study comprising “true” exposure data as well as an extensive collection of candidate predictors from questionnaires or company data, which cannot all be included in the models due to restrictions in the degrees of freedom available for modeling. In these situations, predictors need to be selected using procedures that can identify the best possible subset of predictors among the candidates. The present study compares two strategies for selecting a set of predictor variables. One strategy relies on stepwise hypothesis testing of associations between predictors and exposure, while the other uses cluster analysis to reduce the number of predictors without relying on empirical information about the measured exposure. Both strategies were applied to the same dataset on biomechanical exposure and candidate predictors among computer users, and they were compared in terms of identified predictors of exposure as well as the resulting model fit using bootstrapped resamples of the original data. The identified predictors were, to a large part, different between the two strategies, and the initial model fit was better for the stepwise testing strategy than for the clustering approach. Internal validation of the models using bootstrap resampling with fixed predictors revealed an equally reduced model fit in resampled datasets for both strategies. However, when predictor selection was incorporated in the validation procedure for the stepwise testing strategy, the model fit was reduced to the extent that both strategies showed similar model fit. Thus, the two strategies would both be expected to perform poorly with respect to predicting biomechanical exposure in other samples of computer users.
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| 43. |
- Hjelm, Rikard, et al.
(författare)
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A multi-perspective method for gear efficiency and contact analysis
- 2023
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Ingår i: Results in Engineering (RINENG). - : Elsevier BV. - 2590-1230. ; 20
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Tidskriftsartikel (refereegranskat)abstract
- Modern gearing applications, in particular electrification, impose new challenges in many different fields of engineering and research. In specific, new demands are imposed on gears, including higher rotational speed, lower noise acceptance, and increased efficiency, as well as increased resistance against pitting and scuffing. To meet these demands, a better understanding of gear contacts is needed. The Eurostars project Effigears proposes a novel multi-perspective methodology for assessment of gear efficiency and contact analysis. The methodology consists of using a novel surface treatment method, Triboconditioning (R), implemented in a streamfinishing process, surface measurements using a scattered light method, experimental testing using the standardized FZG test rig, and contact simulations using a novel thermal elasto-hydrodynamic lubrication tool. It is found, in preliminary tests, that enhanced gear performance may be enhanced due to Triboconditioning (R) surface treat-ment. Findings also include better understanding of how surface characteristics and lubricants affect scuffing and pitting, and the effect of load distribution on gearset behavior.
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| 44. |
- Hjelm, Rikard, et al.
(författare)
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Airborne Wear Particles from Dry Clutches
- 2022
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Ingår i: Atmosphere. - : MDPI AG. - 2073-4433. ; 13:10
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Tidskriftsartikel (refereegranskat)abstract
- A significant part of non-exhaust particle emissions in cities comes from the wear of vehicle components. Several studies on airborne particles from the wear of disc brakes and tires have been completed. However, few publications can be found in the scientific literature regarding airborne emissions from dry clutches used in road vehicles. With this in mind, this preliminary study designs a clutch tribometer for the generation of airborne wear particles in a controlled environment. The number concentration and the size distribution of airborne wear particles generated from a typical dry clutch used in passenger cars are investigated. The tests are run at a constant rotational speed, and normal load. The results show that the particle number concentration from dry clutches exhibits a running-in period and a steady state, similar to the particle emissions from disc brake contact. A significant number of nanoparticles (aerodynamic diameter < 100 nm) are emitted from the dry clutch contact.
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| 45. |
- Hjelm, Rikard, et al.
(författare)
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Influence of manufacturing error tolerances on contact pressure in gears
- 2021
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Ingår i: Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science. - : SAGE Publications. - 0954-4062 .- 2041-2983. ; 235:20, s. 5173-5185
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Tidskriftsartikel (refereegranskat)abstract
- Gear manufacturing always results in some degree of manufacturing errors, i.e. deviations from the desired gear geometry. These errors alter how the gears mesh, typically causing increased contact pressure which in turn shortens service life. It is therefore crucial to choose tolerances such that excessive contact pressure, and especially tip contact, is avoided. With increasing demands due to electrification, this becomes even more important. The aim of this paper is to study how pitch error and profile slope error affect the contact pressure in spur gears sets. The meshing is simulated using a novel simulation approach that uses a parametric description of the reference profile and gear geometry, and a hybrid model for the compliance. The method includes tooth modifications such as tip relief, and uses the true geometry to find contacts. Thus, it also handles contact outside the nominal line of action, including tip contact. The study includes cases where a gear is subjected to both pitch error and profile slope error simultaneously. Numerical examples, relevant to the automotive industry, show the outcome of the simulations. It is shown how simulation-based tolerances for relevant industrial applications can be used to improve manufacturing outcome.
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| 46. |
- Hjelm, Rikard, et al.
(författare)
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Influence of Manufacturing Error Tolerances on Thermal EHL Behavior of Gears
- 2022
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Ingår i: Lubricants. - : MDPI AG. - 2075-4442. ; 10:11
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Tidskriftsartikel (refereegranskat)abstract
- Due to the electrification of vehicles, new demands are being imposed on gears, which translates to the tolerances of manufacturing errors. However, not many studies treat the impact of manufacturing error combinations on the lubricant behavior of gear sets. Therefore, a simulation method is developed, including its derivation, discretization, and implementation. The method solves the thermal elasto-hydrodynamic lubrication (TEHL) problem, taking into account the varying temperature, viscosity, density, and cavitation of the lubricant. To account for manufacturing errors, the load distribution from a loaded tooth contact analysis (LTCA), developed by the authors, is used as input to the TEHL method. Comparison is made with a standard load distribution assumption, and a numerical example is used to show some preliminary results. The results show good agreement with results from other studies. It is shown that there is a great effect of manufacturing errors on the TEHL behavior, such as temperature, due to the change in load distribution such errors impose. It can be concluded that manufacturing errors of different tolerances have a great impact and that they should therefore be taken into consideration when analyzing gear set behavior and constructing gear sets for new applications.
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| 47. |
- Hjelm, Rikard, et al.
(författare)
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Reducing scrapping of gears by assessment of tip contact threshold torque
- 2022
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Ingår i: Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology. - : SAGE Publications. - 1350-6501 .- 2041-305X. ; 236:8, s. 1613-1622
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Tidskriftsartikel (refereegranskat)abstract
- While striving for more competitive products as well as reaching the Global Sustainable Development Goals, automotive powertrain manufacturers increase the demands on gears, which translates to decreased manufacturing error tolerances. Too tight tolerances may, however, counteract the goal if it leads to increased material and energy consumption due to unjustified scrapping. This paper presents a method to prevent unjustified scrapping by comparing the severity of different manufacturing error tolerances by means of the tip contact threshold torque. Curve fits are shown to be accurate and helpful to assess the outcome of a produced batch of gears. A case study is made where the method is used with measured data from the industry. It can be concluded from the investigation that considerable amounts of scrapping can be avoided by consideration of the threshold torque.
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| 48. |
- Hjelm, Rikard, et al.
(författare)
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Ultrafine particle emissions from dry clutches : number concentration, size distribution and chemical composition
- 2024
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Ingår i: Environmental Science. - : Royal Society of Chemistry (RSC). - 2634-3606. ; 4:1, s. 35-42
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Tidskriftsartikel (refereegranskat)abstract
- Non-exhaust sources, such as brakes, tyres, roads, and clutches, emit a large portion of airborne particles in road transportation, from ultrafine to coarse sizes. While airborne wear particle emissions from brakes and road-tyre contacts have been studied extensively, emissions from clutches have been overlooked. A preliminary study using a novel test rig has indicated that dry clutches also emit airborne wear particles. This paper presents a multi-method for the assessment of ultrafine particles from dry clutches regarding the number concentration, size distribution and chemical composition. The results show that ultrafine particles are emitted both during run-in and at the steady state, featuring a bi-modal size distribution. Elementary analysis shows that the particles consist of several elements, predominately iron, silicon, and sulfur. It can be concluded from this study that ultrafine particles are always generated when the clutch is operated. Clutches in automobiles are shown to produce ultrafine particles, consisting of several metallic elements, which become airborne.
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| 49. |
- Händel, Peter, et al.
(författare)
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Insurance telematics : Opportunities and challenges with the smartphone solution
- 2014
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Ingår i: IEEE transactions on intelligent transportation systems (Print). - 1524-9050 .- 1558-0016. ; 6:4, s. 57-70
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Tidskriftsartikel (refereegranskat)abstract
- Smartphone-based insurance telematics or usage based insurance is a disruptive technology which relies on insurance premiums that reflect the risk profile of the driver; measured via smartphones with appropriate installed software. A survey of smartphone-based insurance telematics is presented, including definitions; Figure-of-Merits (FoMs), describing the behavior of the driver and the characteristics of the trip; and risk profiling of the driver based on different sets of FoMs. The data quality provided by the smartphone is characterized in terms of Accuracy, Integrity, Availability, and Continuity of Service. The quality of the smartphone data is further compared with the quality of data from traditional in-car mounted devices for insurance telematics, revealing the obstacles that have to be combated for a successful smartphone-based installation, which are the poor integrity and low availability. Simply speaking, the reliability is lacking considering the smartphone measurements. Integrity enhancement of smartphone data is illustrated by both second-by-second lowlevel signal processing to combat outliers and perform integrity monitoring, and by trip-based map-matching for robustification of the recorded trip data. A plurality of FoMs are described, analyzed and categorized, including events and properties like harsh braking, speeding, and location. The categorization of the FoMs in terms of Observability, Stationarity, Driver influence, and Actuarial relevance are tools for robust risk profiling of the driver and the trip. Proper driver feedback is briefly discussed, and rule-of-thumbs for feedback design are included. The work is supported by experimental validation, statistical analysis, and experiences from a recent insurance telematics pilot run in Sweden.
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| 50. |
- Jackson, Jennie A., et al.
(författare)
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Is what you see what you get? : Standard inclinometry of set upper arm elevation angles
- 2015
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Ingår i: Applied Ergonomics. - : Elsevier BV. - 0003-6870 .- 1872-9126. ; 47, s. 242-252
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Tidskriftsartikel (refereegranskat)abstract
- Previous research suggests inclinometers (INC) underestimate upper arm elevation. This study was designed to quantify possible bias in occupationally relevant postures, and test whether INC performance could be improved using calibration. Participants were meticulously positioned in set arm flexion and abduction angles between 0 degrees and 150 degrees. Different subject-specific and group-level regression models comprising linear and quadratic components describing the relationship between set and INC-registered elevation were developed using subsets of data, and validated using additional data. INC measured arm elevation showed a downward bias, particularly above 600. INC data adjusted using the regression models were superior to unadjusted data; a subject-specific, two-point calibration based on measurements at 0 and 900 gave results closest to the 'true' set angles. Thus, inclinometer measured arm elevation data required calibration to arrive at 'true' elevation angles. Calibration to a common measurement scale should be considered when comparing arm elevation data collected using different methods.
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