| 1. |
- El-Sallabi, H., et al.
(author)
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Wideband spatial channel model for MIMO systems at 5 GHz in indoor and outdoor environments
- 2006
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In: IEEE Vehicular Technology Conference. ; , s. 2916-2921
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Conference paper (peer-reviewed)abstract
- This work presents a spatial channel model developed within the EC WINNER1 project. The channel model is mainly based on double-directional measurement campaigns carried out in the 5 GHz ISM 2 band with bandwidths of up to 120 MHz. The model is based on a unified structure for indoor and outdoor environment. It covers 6 different propagation scenarios, namely indoor small office, indoor hall, urban microcell, urban macrocell, suburban macrocell, and rural environment. Both line-of-sight (LOS) and non-line-of-sight (NLOS) propagation conditions are modeled.
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| 2. |
- Falconer, D., et al.
(author)
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New Air-interface Technologies and Deployment Concepts
- 2006
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In: Technologies for the Wireless Future: Wireless World Research Forum (WWRF). - Chichester, UK : John Wiley & Sons. - 0470029056 - 9780470029053 ; , s. 131-226
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Book chapter (other academic/artistic)
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| 3. |
- Hemphälä, H, et al.
(author)
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A method for assessing risks in visual ergonomics
- 2015
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In: Proceedings of Nordic Ergonomics Society 47th Annual Conference. - 9788299574754
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Conference paper (peer-reviewed)abstract
- A method for risk assessment in the field of visual ergonomics is under development. Insufficient visual ability can lead to increased workload and contribute to eyestrain and musculoskeletal discomfort. Although the relation between eyestrain and musculoskeletal discomfort is not fully understood, studies have shown that straining the eyes increases the musculoskeletal activity in the neck and shoulders (trapezius); associations between visually demanding work, eye problems, headaches and/or muscle problems have also been found (Aarås et al., 2001; IESNA, 2011; Zetterlund et al., 2009; Zetterberg et al., 2013; Toomingas et al., 2013; Richter et al., 2011; Richter et al., 2015). Problems due to insufficient visual ergonomics not only exist in computer intensive work, but in other professions as well, such as surgeons and postal workers (Hemphälä et al., 2011; Hemphälä et al., 2012). The aim of this project is to develop a practical, easy-to-use, and time efficient risk assessment method for visual ergonomics. With this method, risk factors in the visual environment can be detected, and interventions implemented to reduce the prevalence of symptoms related to poor visual ergonomics among workers.
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| 4. |
- Richter, Hans O., et al.
(author)
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Prefrontal Cortex Oxygenation Evoked by Convergence Load Under Conflicting Stimulus-to-Accommodation and Stimulus-to-Vergence Eye-Movements Measured by NIRS
- 2018
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In: Frontiers in Human Neuroscience. - : Frontiers Media SA. - 1662-5161. ; 12
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Journal article (peer-reviewed)abstract
- Purpose: To extend our knowledge of the functional linkages between visual fatigue and regional cerebral prefrontal cortex (PFC) oxygenation, we measured time related hemodynamic changes over the right dorsolateral prefrontal cortex (dlPFC) during convergence load under conflicting stimulus-to-accommodation and stimulus-to-vergence eye movements with and without concurrent mental load.Methods: Twenty healthy participants with a median age of 28 years (range: 18–44 years) fixated upon a vertical bar presented separately to the left and right eyes, using polarized filters, during four counterbalanced 10-min periods: (i) no accommodation/vergence conflict (Control, Ctrl); (ii) added convergence load and accommodation/vergence conflict (Conv); (iii) added cognitive load only (Cog) and; (iv) a combination of added cognitive and convergence load and accommodation/vergence conflict (Cc). Viewing distance was 65 cm. Non-invasive measurements of hemodynamic activity over the dlPFC were quantified by functional near-infrared spectroscopy (fNIRS). During the two-convergence load conditions, the horizontal disparity of the two bars varied dynamically from no disparity to a disparity set 20% below the individual threshold for diplopia. Cognitive load was induced by the n-back-2 test which required the subject to memorize and recall the changing colors of the horizontal bars and decide when a given color was the same as that occurring two colors previously. fNIRS data were averaged over 10-s windows centered at 0, 2, 4, 6, 8, and 10 min of each task, subtracted from a 20-s baseline window immediately preceding the visual task, and then represented as changes in oxygenated hemoglobin (ΔHbO2), deoxygenated hemoglobin (ΔHHb) and total hemoglobin (ΔtHb).Results: Linear mixed model analyses showed that hemodynamic activity was systematically influenced by time (p < 0.001). The group-averaged time-related level of change across the viewing conditions did not differ when compared with one another (p > 0.05). Larger convergence eye-movement responses under conflicting stimulus-to-accommodation, and stimulus-to-vergence over time, increased ΔHbO2 and ΔtHb only in condition Cc and after 8 min of task time (p < 0.10 for min-6 and min-8: p < 0.05 for min-10).Discussion: Collectively, our data suggest that HbO2, HHb, and tHb, recorded over the dlPFC with fNIRS, can be used to assay the degree to which supervisory oculomotor control processes are activated during visually deficient near work.
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| 5. |
- Rosén, Anders, 1970, et al.
(author)
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Biomarkers of neuronal damage in saturation diving—a controlled observational study
- 2020
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In: European Journal of Applied Physiology. - : Springer Nature. - 1439-6319 .- 1439-6327.
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Journal article (peer-reviewed)abstract
- Purpose: A prospective and controlled observational study was performed to determine if the central nervous system injury markers glial fibrillary acidic protein (GFAp), neurofilament light (NfL) and tau concentrations changed in response to a saturation dive. Methods: The intervention group consisted of 14 submariners compressed to 401 kPa in a dry hyperbaric chamber. They remained pressurized for 36 h and were then decompressed over 70 h. A control group of 12 individuals was used. Blood samples were obtained from both groups before, during and after hyperbaric exposure, and from the intervention group after a further 25–26 h. Results: There were no statistically significant changes in the concentrations of GFAp, NfL and tau in the intervention group. During hyperbaric exposure, GFAp decreased in the control group (mean/median − 15.1/ − 8.9 pg·mL−1, p < 0.01) and there was a significant difference in absolute change of GFAp and NfL between the groups (17.7 pg·mL−1, p = 0.02 and 2.34 pg·mL−1, p = 0.02, respectively). Albumin decreased in the control group (mean/median − 2.74 g/L/ − 0.95 g/L, p = 0.02), but there was no statistically significant difference in albumin levels between the groups. In the intervention group, haematocrit and mean haemoglobin values were slightly increased after hyperbaric exposure (mean/median 2.3%/1.5%, p = 0.02 and 4.9 g/L, p = 0.06, respectively). Conclusion: Hyperbaric exposure to 401 kPa for 36 h was not associated with significant increases in GFAp, NfL or tau concentrations. Albumin levels, changes in hydration or diurnal variation were unlikely to have confounded the results. Saturation exposure to 401 kPa seems to be a procedure not harmful to the central nervous system. Trial registration: ClinicalTrials.gov NCT03192930.
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| 6. |
- Zetterberg, Camilla, 1970-, et al.
(author)
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Workshop in visual ergonomics
- 2013
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Conference paper (peer-reviewed)abstract
- Increased use of computers is common across many work sectors. Prolonged near work at a computer screen is associated with both visual discomfort and neck/shoulder discomfort and pain. Inadequate visual ergonomics at a computer workstation can also influence both visual and neck/shoulder discomfort. The new provision from the Swedish Work Environment Authority on prevention of musculoskeletal disorders includes risk assessment of occupational visual conditions. These assessments require practitioners to have knowledge of the topic, as well as experience with practical assessment tools.The first part of the workshop proposed here will involve a presentation of the theories underlying visual ergonomic practices and a discussion of the most important factors to assess at a computer workstation. These factors include contrast, font size, resolution, glare, reflexion, non-visual flicker, and edge sharpness. The second part of the workshop, will allow participants hands-on practice in measuring and evaluating visual ergonomics at a computer workstation.
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