| 1. |
- Almgren, Johanna, et al.
(författare)
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Patients' Health Experiences of Post COVID-19 Condition – A Qualitative Study
- 2022
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Ingår i: International Journal of Environmental Research and Public Health. - Basel : MDPI. - 1661-7827 .- 1660-4601. ; 19:21
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Tidskriftsartikel (refereegranskat)abstract
- Patients who suffer from long-term symptoms of COVID-19, described as post COVID-19 condition, are a new and large group of patients. There is a lack of knowledge concerning health experiences in this patient group. The aim of this study was to explore patients' health experiences of post COVID-19 condition. Data collection was performed through 14 semi-structured interviews. The qualitative content analysis resulted in six sub-categories, three categories, and an overall theme. Patients experienced symptoms of varying duration-ranging from 5-21 months. The results showed that patients' health experiences of post COVID-19 condition moved between uncertainty and new insights. This was shown by patients experiencing: (1) loss of abilities, including losing smell and taste and lacking energy, (2) loss of control, including being foreign to oneself and seeking answers, and (3) revaluation of life, including accepting the transformed body and prioritizing health. This study illustrates that patients living with post COVID-19 condition need to be treated with flexibility, based on each individual's unique challenges and experiences of the symptoms and the consequences for their health. © 2022 by the authors.
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| 2. |
- Larsson, Ingrid, 1968-, et al.
(författare)
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Validity and reliability of the Swedish version of the Children’s Sleep Habits Questionnaire (CSHQ-SWE)
- 2024
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Ingår i: BMC Pediatrics. - London : BioMed Central (BMC). - 1471-2431. ; 24:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: To translate and culturally adapt the Children’s Sleep Habits Questionnaire (CSHQ) to a Swedish version, CSHQ-SWE, and to assess its validity and reliability for use with children with attention deficit hyperactivity disorder (ADHD). Methods: A total of 84 children with ADHD (51 boys and 33 girls; 6–12 years) and parents (7 men and 77 women; 28–51 years) were included in the study. CSHQ was translated and culturally adapted to Swedish, and assessed for concurrent validity with sleep actigraphy (analyzed by Kendall’s Tau) and for reliability by internal consistency (analyzed by McDonald’s Omega H). Face and content validity was evaluated by parents (n = 4) and healthcare professionals (n = 6) qualitatively (comprehensiveness, relevance, and comprehensibility assessed by interviews and analyzed by thematic analysis) and quantitatively (analyzed by content validity ratio and content validity index for 33 items and four non-scored inquiries). Results: Parent-reported sleep problems (CSHQ-SWE total score) were moderately correlated with less “Sleep Efficiency” (Tau = −0.305; p < 0.001) measured by sleep actigraphy. Parent-reported problems with “Sleep Onset Delay” was moderately correlated with measured time for ”Sleep Onset Latency” (Tau = 0.433; p < 0.001). Parent-reported problems with “Night Wakings” were weakly correlated with measured time for “Wake After Sleep Onset” (Tau = 0.282; p < 0.001). Parents estimation of “Total daily sleep duration” was moderately correlated with measured “Total Sleep Time” (Tau = 0.386; p < 0.001). Five of the seven subscales reached an acceptable level for internal consistency (McDonald’s Omega H > 0.700). Comprehensiveness, relevance, and comprehensibility of CSHQ-SWE were satisfactory overall. Content validity ratio was 0.80 to 1.00 for six items, 0.00 to 0.60 for 22 items, and < 0.00 for nine items. Content validity index was 0.22. Conclusions: CSHQ-SWE demonstrated acceptable concurrent validity with objectively measured sleep and internal consistency, whereas the overall results of face and content validity assessment varied. The instrument needs to be further evaluated regarding construct validity, responsiveness, test-retest reliability, and its generalization to other populations. © The Author(s) 2024
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| 3. |
- Lyu, Yezhe, et al.
(författare)
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Tribology and airborne particle emissions from grey cast iron and WC reinforced laser cladded brake discs
- 2024
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Ingår i: Wear. - 0043-1648. ; 556-557
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Tidskriftsartikel (refereegranskat)abstract
- Laser cladding (LC) is a promising technique to overlay a protective coating on grey cast iron (GCI) brake discs to enhance the wear and corrosion resistance. This study utilized a pin-on-disc tribometer in an aerosol chamber to investigate the tribology and airborne particle emissions from tungsten carbides (WC) reinforced coating overlayed onto GCI substrate through laser cladding. Uncoated GCI brake discs served as reference material, while low-metallic (LM) and non-asbestos organic (NAO) brake pads were used as counterparts. The results indicate that LC coating exhibited slightly higher coefficient of friction and significantly lower wear than uncoated GCI discs. Abrasive wear is the dominant wear mechanism for both uncoated GCI brake discs and LC coatings. LC coatings substantially decreased the particle mass concentrations. All three friction pairs displayed a mass weighted size distribution with a major peak around 2–3 μm. The number size distribution was dominated by a mode below 1 μm. Emissions by number were generally low. Meanwhile, all three friction pairs emitted sheared off and agglomerated particles, with iron being the dominant element. Tungsten was identified in the particles emitted from LC coatings, indicating that the hard coating has a potential to wear off and become airborne particles.
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| 4. |
- Malmborg, Jens
(författare)
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Numerical modeling of train-induced ground vibrations
- 2020
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The population is growing, and an increasing proportion of the population live in urban areas. As a consequence, human exposure to noise and vibrations is increasing. Larger and denser cities lead to a higher amount of traffic close to where people work and live. Land close to railways and heavily trafficked roads, previously left unexploited, are now being used for dwellings and offices. Vibrations are often accompanied by noise, to which longterm exposure is known to have serious health effects. Furthermore, some buildings such as hospitals and research facilities contain instruments that are highly sensitive to vibrations, and require proper vibration isolation to ensure safe operation. To address the problems of noise and vibrations, their generation and propagation need to be understood.In this thesis, numerical modeling strategies for predicting groundbornevibrations from a surface railway track have been studied. Focus have been on the vibration transmission from the track to the freefield, and to a smaller extent on the actual load generation due to a train running on an uneven rail.The wave propagation in the ground resulting from the dynamic loads on the track can be calculated using numerous numerical techniques. The finite element method offers a large flexibility regarding modeling capabilities in terms of geometrical conditions and material properties. However, the need for discretizing a large soil volume, under and between the track and the receiver, can generate very large systems of equations that are timeconsuming or practically impossible to solve. Computational savings can be made by introducing a coordinate transformation into the governing equations, so that the computational model is formulated in a moving frame of reference following the vehicle. Furthermore, if a horizontally layered viscoelastic halfspace is assumed, a so called Green’s function (a fundamental solution) for the ground dynamic response can be found very efficiently by employing a semianalytical solution procedure in frequency–wavenumber domain. Here, the Green’s function in a moving reference frame was used for establishing a dynamic stiffness matrix for a set of points in the track–soil interface, to which a finite element representation of the track was coupled. After solving the coupled track–soil problem, the Green’s function was used again to obtain the freefield ground vibrations resulting from the forces in the track–soil interface. The influence of different modeling strategies regarding the railway track was investigated, and further the change in response due to a mitigation measure under the track was studied using this model.Additional efficiency may be obtained by applying a so called 2.5D procedure, in which a Fourier transform with regards to the track direction coordinate is performed. Instead of solving one large 3D problem, a sequence of 2D problems is solved for a set of discrete wavenumbers, after which the 3D response is recovered by an inverse Fourier transform. In the thesis, a very time efficient model is formulated that employs a 2.5D finite element representation of the railway track, coupled to a dynamic stiffness matrix of the layered ground obtained using the aforementioned semianalytical approach.Finally, a 2.5D model employing finite elements for both the track and the surrounding soil was implemented and compared to the two previously mentioned coupled models, showing very good agreement.
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| 5. |
- Malmborg, Jens, et al.
(författare)
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Prediction models of free-field vibrations from railway traffic
- 2017
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Ingår i: COMPDYN 2017 : 6 th ECCOMAS Thematic Conference on Computational Methods in Structural Dynamics and Earthquake Engineering - 6 th ECCOMAS Thematic Conference on Computational Methods in Structural Dynamics and Earthquake Engineering. - Athens : Institute of Structural Analysis and Antiseismic Research School of Civil Engineering National Technical University of Athens (NTUA) Greece. ; , s. 4810-4820
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Konferensbidrag (refereegranskat)abstract
- Many cities experience an increasing population leading to a need for urban densification. In these cities, unused land close to railways will have to be developed with new residential and office buildings. The infrastructural demand will also increase, resulting in heavily trafficked roads and railways close to w here people work and live. Annoyance from traffic-induced vibrations and noise is expected to be a growing issue. To predict the level of vibration and noise in buildings caused by railway and road traffic, calculation models are needed.In the present pa per, a simplified prediction model is briefly described. This prediction model is based on the assumption that the ground and railway embankment can be described in an axisymmetric model , to provide the transfer functions between the track and the free-field . In the paper, the error that arise by assuming axisymmetric response is studied by comparing the response in a three-dimensional finite-element model. Transfer functions at several positions in the free-field are compared
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| 6. |
- Malmborg, Julia S., PhD, 1988-, et al.
(författare)
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Parents' health experiences after their child with ADHD and sleep problems underwent a sleep intervention with a weighted blanket
- 2023
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Konferensbidrag (refereegranskat)abstract
- Background: Being a parent of a child with attention deficit hyperactivity disorder (ADHD) and sleep problems can be challenging and stressful. Weighted blankets have the potential to improve sleep and health in these children, but less is known about the potential effects the child's use of a weighted blanket may have on parents' health.Purpose of the study: To explore parents' health experiences after their child with ADHD and sleep problems underwent a sleep intervention with a weighted blanket.Methods: This study is a part of a randomized, controlled crossover trial with a 16-week sleep intervention with weighted blankets for children with ADHD and sleep problems. A total of 24 parents of children who preferred sleeping with a weighted blanket were interviewed about how the sleep intervention influenced their health. An inductive qualitative content analysis resulted in seven subcategories and two categories.Findings: Children's sleep with weighted blankets influenced parents experienced health in terms of 1) coping with everyday life, including finding harmony, nurturing family relationships, and maintaining a sustainable structure, and 2) feeling well-being, including being well rested, sustaining energy, reaching calm, and achieving meaningful leisure time.Conclusion: A sleep intervention with weighted blankets in children with ADHD and sleep problems influenced parents' health positively by improving management of life and well-being. For parents who struggle to meet the everyday challenges of their child's ADHD, this sleep intervention may contribute to a sustainable health.
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| 7. |
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| 8. |
- Malmborg, Jens
(författare)
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Vibrations from Railway Traffic : Computational Modeling and Analysis
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The population is growing, and an increasing proportion of the population lives in urban areas. As a consequence, human exposure to noise and vibrations is increasing; two major sources being railway and road traffic. Larger and denser cities lead to a higher amount of traffic close to where people work and live. Land close to railways and heavily trafficked roads, previously left unexploited, are now being used for dwellings and offices. Vibrations are often accompanied by noise, to which long-term exposure is known to have serious health effects. Furthermore, some buildings such as hospitals and research facilities contain instruments that are highly sensitive to vibrations, and require proper vibration isolation to ensure safe operation. To address the problems of noise and vibrations, their generation and propagation need to be understood. The vibrations next to a railway track are caused by the forces exerted on the track by the passing train. These forces are the sum of a quasi-static part due to the deadweight of the train, and a dynamic part. The dynamic part is caused by various phenomena resulting in time-dependent train–track interaction forces. The vibrations generated at the track propagate through the underlying and surrounding soil as elastic waves of various types. The mechanical properties of the soil strongly influence the wave propagation and the resulting vibrations registered by a receiver at some distance from the track. For a building structure next to the track, the vibrations inside the building furthermore depend on the mechanical and geometrical properties of the building’s structural elements.In the thesis, numerical models and modeling strategies for predicting ground-borne vibrations from railway tracks have been developed. Various techniques to calculate the wave propagation in the soil have been implemented and used for studying different phenomena, such as the vibrations at the soil surface and in a building next to the track, caused by a train running over an uneven rail. Furthermore, the mitigation of traininduced ground vibrations and so called “critical velocity” effects, i.e. highspeed trains moving faster than the wave speed in the underlying soil, were studied. In addition, models developed in the thesis were utilized to compare the dynamic responses of a heavyweight concrete building and a lightweight wooden building, when excited by ground vibrations induced by a train moving over an uneven rail.
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| 9. |
- Novakovic, Maja, et al.
(författare)
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Regulated Emissions and Detailed Particle Characterisation for Diesel and RME Biodiesel Fuel Combustion with Varying EGR in a Heavy-Duty Engine
- 2019
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Ingår i: SAE Technical Paper Series. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191. ; 2019:December
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates particulate matter (PM) and regulated emissions from renewable rapeseed oil methyl ester (RME) biodiesel in pure and blended forms and contrasts that to conventional diesel fuel. Environmental and health concerns are the major motivation for combustion engines research, especially finding sustainable alternatives to fossil fuels and reducing diesel PM emissions. Fatty acid methyl esters (FAME), including RME, are renewable fuels commonly used from low level blends with diesel to full substitution. They strongly reduce the net carbon dioxide emissions. It is largely unknown how the emissions and characteristics of PM get altered by the combined effect of adding biodiesel to diesel and implementing modern engine concepts that reduce nitrogen oxides (NOx) emissions by exhaust gas recirculation (EGR). Therefore, the exhaust from a single-cylinder Scania D13 heavy-duty (HD) diesel engine fuelled with petroleum-based MK1 diesel, RME, and a 20% RME blend (B20), was sampled while the inlet oxygen concentration was stepped from ambient to very low by varying EGR. Regulated gaseous emissions, mass of total black carbon (BC) and organic aerosol (OA), particle size distributions and the soot nanostructure by means of transmission electron microscopy (TEM), were studied. For all EGR levels, RME showed reduced BC emissions (factor 2 for low and 3-4 for higher EGR) and total particulate number count (TPNC) compared with diesel and B20. B20 was closer to diesel than RME in emission levels. RME opens a significant possibility to utilise higher levels of EGR and stay in the region of low NOx, while not producing more soot than with diesel and B20. Adding EGR to 15% inlet O2 did not affect the nanostructure of PM. A difference between the fuels was noticeable: branched agglomerates of diesel and RME were composed of many primary particles, whereas those of B20 were more often “melted” together (necking).
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| 10. |
- Varriale, Francesco, et al.
(författare)
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On the impact of pad material ingredients on particulate wear emissions from disc brakes
- 2023
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Ingår i: Results in Engineering. - 2590-1230. ; 19
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Tidskriftsartikel (refereegranskat)abstract
- Besides friction and wear, airborne particle emission has become a central parameter when evaluating disc brake performance due to its potential adverse health effects as component of ambient air pollution. The pad friction material of brake system is composed of a mixture of ingredients grouped into four material categories: abrasives, reinforcing fibres, lubricants, and fillers. Some other ingredients which do not typically belong to aforementioned categories can be attributed to “fixed material”, such as aramid fibre, which is usually added into brake pad to harmonize the overall tribological properties. There is a gap of knowledge about how one ingredient from one category contributes to the emissions of particle number (PN) and mass (PM2.5, PM10). To investigate this, one ingredient from each category was chosen and produced as pins. As a reference, pins made of a commercial European brake friction material were also produced. The pins were tested using a pin-on-disc tribometer designed for airborne emission studies. Coefficient of friction, particle mass and number concentrations were measured during the tests. The results indicate that the abrasive and metal fibre have PN, PM2.5, and PM10 emission factors that are orders of magnitude higher than the lubricant and aramid fibre.
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