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| 2. |
- Koch, Markus, et al.
(författare)
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Frequency of breaks, amount of muscular rest, and sustained muscle activity related to neck pain in a pooled dataset
- 2024
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Ingår i: PLoS ONE. - 1932-6203. ; 19:6, s. 1-22
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Neck pain remains a persistent challenge in modern society and is frequently encountered across a wide range of occupations, particularly those involving repetitive and monotonous tasks. It might be expected that patterns of trapezius muscle activity at work, characterized by few breaks and prolonged periods of sustained muscle activity, are linked to neck pain. However, previous cross-sectional studies have generally failed to establish a definitive association. While some longitudinal studies have suggested that extended periods of heightened muscle activity could be a risk factor for neck pain, these findings often relied on limited participant numbers or specific professional groups. This study aimed to investigate the relationship between trapezius muscle activity and neck pain by pooling data from seven Scandinavian research institutes encompassing a diverse range of occupational backgrounds.METHODS: Electromyographic (EMG) data for the upper trapezius muscle, collected during working hours, were coupled with questionnaire responses pertaining to neck pain, individual characteristics, and potential confounding variables for a total of 731 subjects. Additionally, longitudinal data from 258 subjects were available. The various EMG datasets were consolidated into a standardized format, and efforts were made to harmonize inquiries about neck pain. Regression analyses, adjusting for sex and height, were conducted to explore the associations between muscle activity variables and neck pain. An exposure index was devised to quantify the cumulative neck load experienced during working hours and to differentiate between various occupational categories.RESULTS: The cross-sectional data displayed a distinct pattern characterized by positive associations for brief periods of sustained muscle activity (SUMA) and negative associations for prolonged SUMA-periods and neck pain. The longitudinal data exhibited a contrasting trend, although it was not as pronounced as the cross-sectional findings. When employing the exposure index, notable differences in cumulative muscle load emerged among occupational groups, and positive associations with longitudinal neck pain were identified.DISCUSSION: The results suggest that individuals with neck pain experience higher cumulative workloads and extended periods of muscle activity over the long term. In the short term, they appear to compensate by taking frequent short breaks, resulting in a lower cumulative workload. Regardless of their occupation, it is crucial to distribute work breaks throughout the workday to ensure that the cumulative load remains manageable.
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| 3. |
- Zalden, Peter, et al.
(författare)
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Femtosecond x-ray diffraction reveals a liquid–liquid phase transition in phase-change materials
- 2019
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Ingår i: Science. - Washington, DC : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 364:6445, s. 1062-1067
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Tidskriftsartikel (refereegranskat)abstract
- In phase-change memory devices, a material is cycled between glassy and crystalline states. The highly temperature-dependent kinetics of its crystallization process enables application in memory technology, but the transition has not been resolved on an atomic scale. Using femtosecond x-ray diffraction and ab initio computer simulations, we determined the time-dependent pair-correlation function of phase-change materials throughout the melt-quenching and crystallization process. We found a liquid–liquid phase transition in the phase-change materials Ag4In3Sb67Te26 and Ge15Sb85 at 660 and 610 kelvin, respectively. The transition is predominantly caused by the onset of Peierls distortions, the amplitude of which correlates with an increase of the apparent activation energy of diffusivity. This reveals a relationship between atomic structure and kinetics, enabling a systematic optimization of the memory-switching kinetics.
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| 4. |
- Allaf Navirian, Hengameh, et al.
(författare)
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Acoustically driven ferroelastic domain switching observed by time-resolved x-ray diffraction
- 2010
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Ingår i: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121. ; 81:2
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Tidskriftsartikel (refereegranskat)abstract
- Domain polarization switching in potassium dihydrogen phosphate (KH2PO4, KDP) induced by a propagating strain wave has been observed with time-resolved x-ray diffraction. A pulsed electric field with amplitude of 6 kV/cm and duration of 1 mu s was applied along the crystallographic c axis. The field-induced strain waves emanating from the sample surfaces are the result of the converse piezoelectric effect. In the center of the probed surface two waves interfered constructively inducing ferroelastic domain switching, in the absence of an external electric field, at a delay of 3 mu s, corresponding to acoustic propagation at a velocity found to be 1500 m/s.
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| 5. |
- Allaf Navirian, Hengameh, et al.
(författare)
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Repetitive ultrafast melting of InSb as an x-ray timing diagnostic
- 2008
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Ingår i: Applied Physics Reviews. - : AIP Publishing. - 1931-9401. ; 103:10, s. 6-103510
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Tidskriftsartikel (refereegranskat)abstract
- We have demonstrated the possibility of using repetitive ultrafast melting of InSb as a timing diagnostic in connection with visible-light pump/x-ray probe measurements at high-repetition-rate x-ray facilities. Although the sample was molten and regrown approximately 1x10(6) times, a distinct reduction in time-resolved x-ray reflectivity could be observed using a streak camera with a time resolution of 2.5 ps. The time-resolved x-ray reflectivity displayed this distinct decrease despite the fact that the average reflectivity of the sample had fallen to approximately 50% of its original value due to accumulated damage from the prolonged laser exposure. The topography of the laser-exposed sample was mapped using an optical microscope, a stylus profilometer, photoelectron microscopy, and a scanning tunneling microscope. Although the surface of the sample is not flat following prolonged exposure at laser fluences above 15 mJ/cm(2), the atomic scale structure regrows, and thus, regenerates the sample on a nanosecond timescale. In the fluence range between 15 and 25 mJ/cm(2), the laser power is sufficient to melt the sample, while regrowth occurs with a sufficiently good structure to allow the extraction of timing information via ultrafast time-resolved x-ray measurements. This can be applied for timing purposes at synchrotron radiation and x-ray free-electron laser facilities. It is also noteworthy that we were able to reproduce the fluence dependencies of melting depth and disordering time previously obtained in single-shot, nonthermal melting experiments with higher temporal resolution.
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| 6. |
- Arvidsson, Inger, et al.
(författare)
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Action Levels for the Prevention of Work-Related Musculoskeletal Disorders in the Neck and Upper Extremities : A Proposal
- 2021
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Ingår i: Annals of Work Exposures and Health. - : Oxford University Press (OUP). - 2398-7308 .- 2398-7316. ; 65:7, s. 741-747
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Tidskriftsartikel (refereegranskat)abstract
- There are several well-known risk factors for work-related musculoskeletal disorders (MSDs). Despite this knowledge, too many people still work in harmful conditions. The absence of occupational exposure limits (OELs) for physical workload impedes both supervision and preventive work. To prevent myalgia, tendon disorders, and nerve entrapments in the upper musculoskeletal system, we propose action levels concerning work postures, movement velocities and muscular loads recorded by wearable equipment. As an example, we propose that wrist velocity should not exceed 20°/s as a median over a working day. This has the potential to reduce the prevalence of carpal tunnel syndrome (CTS) in highly exposed male occupational groups by 93%. By reducing upper arm velocity in highly exposed female groups to the suggested action level 60°/s, the prevalence of pronounced neck/shoulder myalgia with clinical findings (tension neck syndrome) could be reduced by 22%. Furthermore, we propose several other action levels for the physical workload. Our ambition is to start a discussion concerning limits for physical workload, with the long-term goal that OELs shall be introduced in legislation. Obviously, the specific values of the proposed action levels can, and should, be discussed. We hope that quantitative measurements, combined with action levels, will become an integral part of systematic occupational health efforts, enabling reduction and prevention of work-related MSDs.
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| 8. |
- Burza, Matthias, et al.
(författare)
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Dispersion and monochromatization of x-rays using a beryllium prism
- 2015
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Ingår i: Optics Express. - 1094-4087. ; 23:2, s. 620-627
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate experimentally and numerically that an x-ray prism made of beryllium can be used to disperse and monochromatize x-rays. A polished beryllium cuboid was employed as refractive and dispersive optics. The results of a proof-of-principle experiment and methods of performance optimization are presented. The spatial separation of undulator harmonics and their subsequent selection using a slit are described. A numerical study, assuming realistic beam and beamline parameters, suggests that undulator harmonics can be spatially separated in the range from 3 keV to beyond 20 keV, while maintaining throughput above 50%. Refractive optics is particularly suitable for low-repetition-rate sources such as free-electron lasers and other LINAC-based short-pulse sources. (C) 2015 Optical Society of America
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| 9. |
- Dahlqvist, Camilla, et al.
(författare)
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Arbetsbelastning vid städning av hotellrum
- 2017
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Enligt Arbetsmiljöverkets rapport ”Arbetsmiljön 2013” har 40 procent av alla hotell- och kontorsstädare ont i nacke, rygg, axlar eller armar varje vecka. 60 procent av dem känner sig uttröttade i kroppen. Arbets- och miljömedicin (AMM) Syd har tagit fram åtgärdsnivåer för ett antal belastningsmått, ”AMM Syds åtgärdsnivåer för ergonomisk belastning”, och om man överstiger dessa, anser vi att risken för belastningsskada är stor. Vi har studerat hotellrumsstädares belastning och jämfört med våra åtgärdsnivåer.Vi mätte den fysiska arbetsbelastningen hos fjorton kvinnliga hotellrumsstädare under en vanlig arbetsdag, på en deltagare åt gången. De arbetade på sju olika hotell i södra Sverige. Några var anställda av städföretag och några direkt av hotellen.Vi fann att hotellrumsstädare har en väldigt hög arbetsbelastning i övre delen av kroppen, både vad gäller rörelsehastighet, arbetsställningar och muskelansträngning (se Tabell på sid 3). Samtliga deltagare hade för hög rörelsehastighet i överarm och handled och för lite vila i underarmens muskler i jämförelse med våra åtgärdsnivåer. Även vad gäller framåtböjningen av huvudet, överarmens arbetsställning och underarmens muskelbelastning fann vi för höga nivåer. Hotellrumsstädning överskrider nio av våra elva åtgärdsnivåer för ergonomisk belastning. Detta betyder att hotellrumsstädare har en väldigt hög risk att drabbas av belastningsskador.RekommendationerFör att minska risken för belastningsskador bland hotellrumsstädare måste arbetstempot sänkas, genom att minska antalet rum som ingår i en hotellrumsstädares arbetsdag.Personalen bör erbjudas regelbundna medicinska kontroller avseende ergonomiskt belastande arbete så att man tidigt sätter in åtgärder för den arbetstagare eller grupp av arbetstagare som är på väg att utveckla skada i muskler och/eller leder. Arbetsplatsen rekommenderas att ha företagshälsovård knuten till sig, som kan genomföra de medicinska kontrollerna och som kontinuerligt gör riskbedömningar av arbetet. De bör också ha som uppgift att utbilda städpersonalen i ergonomi.
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