| 1. |
- de Alwis, Pahansen, 1980-, et al.
(författare)
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Exposure aboard high-performance Marine craft increases musculoskeletal pain and lowers contemporary work capacity of the occupants
- 2021
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Ingår i: Journal of Engineering for the Maritime Environment (Part M). - : SAGE Publications. - 1475-0902 .- 2041-3084. ; 235:3, s. 750-762
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Tidskriftsartikel (refereegranskat)abstract
- High-Performance Marine Craft (HPMC) occupants are currently being investigated for various psychophysical impairments degrading work performance postulating that these deteriorations are related to their occupational exposures. However, scientific evidence for this is lacking and the association of exposure conditions aboard HPMC with adverse health and performance effects is unknown. Therefore, the study estimates the prevalence of musculoskeletal pain (MSP) among HPMC occupants and the association of their work exposure with MSP and performance degradation. It also presents a criterion for evaluating the self-reported exposure severity aboard three different types of mono-hull HPMC; displacement, semi-displacement and planing, on a par with the available standard criteria for objectively measurable exposures. Furthermore, another criterion is proposed to assess the performance-degradation of HPMC occupants based on self-reported fatigue symptoms and MSP. Swedish Coast Guard HPMC occupants were surveyed for MSP, fatigue symptoms as well as for work-related and individual risk indicators using a validated web-based questionnaire. Prevalence of MSP and performance-degradation during the past 12 months were assessed and presented as a percentage of the sample. Associations of exposure conditions aboard HPMC with MSP and performance-capacity were systematically evaluated using multiple logistic regression models and expressed as odds ratio (OR). Prevalence of MSP was 72% among which lower back pain was the most prevalent (46%) followed by neck pain (29%) and shoulder pain (23%) while 29% with degraded performance. Exposure to severe conditions aboard semi-displacement craft was associated with lower back (OR = 2.3) and shoulder (OR = 2.6) pain while severe conditions aboard planing craft with neck pain (OR = 2.3) and performance-degradation (OR = 2.6). MSP is common among Swedish coast guards. Severe exposure conditions aboard HPMC are significantly associated with both MSP and performance-degradation. The spine and shoulders are the most susceptible to work-related MSP among HPMC occupants which should be targeted in work-related preventive and corrective measures.
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| 2. |
- Lo Martire, Riccardo, et al.
(författare)
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Construction of a web-based questionnaire for longitudinal investigation of work exposure, musculoskeletal pain and performance impairments in high-performance marine craft populations
- 2017
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Ingår i: BMJ Open. - : BMJ. - 2044-6055. ; 7:7
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: High-performance marine craft personnel (HPMCP) are regularly exposed to vibration and repeated shock (VRS) levels exceeding maximum limitations stated by international legislation. Whereas such exposure reportedly is detrimental to health and performance, the epidemiological data necessary to link these adverse effects causally to VRS are not available in the scientific literature, and no suitable tools for acquiring such data exist. This study therefore constructed a questionnaire for longitudinal investigations in HPMCP.METHODS: A consensus panel defined content domains, identified relevant items and outlined a questionnaire. The relevance and simplicity of the questionnaire's content were then systematically assessed by expert raters in three consecutive stages, each followed by revisions. An item-level content validity index (I-CVI) was computed as the proportion of experts rating an item as relevant and simple, and a scale-level content validity index (S-CVI/Ave) as the average I-CVI across items. The thresholds for acceptable content validity were 0.78 and 0.90, respectively. Finally, a dynamic web version of the questionnaire was constructed and pilot tested over a 1-month period during a marine exercise in a study population sample of eight subjects, while accelerometers simultaneously quantified VRS exposure.RESULTS: Content domains were defined as work exposure, musculoskeletal pain and human performance, and items were selected to reflect these constructs. Ratings from nine experts yielded S-CVI/Ave of 0.97 and 1.00 for relevance and simplicity, respectively, and the pilot test suggested that responses were sensitive to change in acceleration and that the questionnaire, following some adjustments, was feasible for its intended purpose.CONCLUSIONS: A dynamic web-based questionnaire for longitudinal survey of key variables in HPMCP was constructed. Expert ratings supported that the questionnaire content is relevant, simple and sufficiently comprehensive, and the pilot test suggested that the questionnaire is feasible for longitudinal measurements in the study population.
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| 3. |
- Stockman, Isabelle, 1984, et al.
(författare)
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Kinematics of Child Volunteers and Child Anthropomorphic Test Devices During Emergency Braking Events in Real Car Environment
- 2013
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Ingår i: Traffic Injury Prevention. - : Informa UK Limited. - 1538-957X .- 1538-9588. ; 14:1, s. 92-102
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: The objective of this study was to present, compare, and discuss the kinematic response of children and child anthropomorphic test devices (ATDs) during emergency braking events in different restraint configurations in a passenger vehicle.Methods: A driving study was conducted on a closed-circuit test track comprising 16 children aged 4 to 12 years old and the Q3, Hybrid III (HIII) 3-year-old, 6-year-old, and 10-year-old ATDs restrained on the right rear seat of a modern passenger vehicle. The children were exposed to one braking event in each of the 2 restraint systems and the ATDs were exposed to 2 braking events in each restraint system. All events had a deceleration of 1.0 g. Short children (stature 107–123 cm) and the Q3, HIII 3-year-old,and 6-year-old were restrained on booster cushions as well as high-back booster seats. Tall children (stature 135–150 cm) and HIII 10-year-old were restrained on booster cushions or restrained by 3-point belts directly on the car seat. Vehicle data were collected and synchronized with video data. Forward trajectories for the forehead and external auditory canal (ear) were determined as well ashead rotation and shoulder belt force.Results: A total of 40 trials were analyzed. Child volunteers had greater maximum forward displacement of the head and greater head rotation compared to the ATDs. The average maximum displacement for children ranged from 165 to 210 mm and 155 to 195 mm for the forehead and ear target, respectively. Corresponding values for the ATDs were 55 to 165 mm and 50 to 160 mm. The change in head angle was greater for short children than for tall children. Shoulder belt force was within the same range for short children when restrained on booster cushions or high-back booster seats. For tall children, the shoulder belt force was greater when restrained on booster cushions compared to being restrained by seat belts directly on the car seat.Conclusions: The forward displacement was within the same range for all children regardless of stature and restraint system. However, themaximum forward position depended on the initial seated posture and shoulder belt position on the shoulder. Differences could also be seen in the curvature of the neck and spine. Short children exhibited a greater flexion motion of the head, whereas a more upright posture at maximumforward position was exhibited by the tall children. The ATDs displayed less forward displacement compared to the children.
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| 4. |
- Biasetti, Jacopo, et al.
(författare)
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An Integrated Fluid-Chemical Model Toward Modeling the Formation of Intra-Luminal Thrombus in Abdominal Aortic Aneurysms
- 2012
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Ingår i: Frontiers in Physiology. - : Frontiers Media SA. - 1664-042X. ; 3:266
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Tidskriftsartikel (refereegranskat)abstract
- Abdominal Aortic Aneurysms (AAAs) are frequently characterized by the presence of an Intra-Luminal Thrombus (ILT) known to influence their evolution biochemically and biomechanically. The ILT progression mechanism is still unclear and little is known regarding the impact of the chemical species transported by blood flow on this mechanism. Chemical agonists and antagonists of platelets activation, aggregation, and adhesion and the proteins involved in the coagulation cascade (CC) may play an important role in ILT development. Starting from this assumption, the evolution of chemical species involved in the CC, their relation to coherent vortical structures (VSs) and their possible effect on ILT evolution have been studied. To this end a fluid-chemical model that simulates the CC through a series of convection-diffusion-reaction (CDR) equations has been developed. The model involves plasma-phase and surface-bound enzymes and zymogens, and includes both plasma-phase and membrane-phase reactions. Blood is modeled as a non-Newtonian incompressible fluid. VSs convect thrombin in the domain and lead to the high concentration observed in the distal portion of the AAA. This finding is in line with the clinical observations showing that the thickest ILT is usually seen in the distal AAA region. The proposed model, due to its ability to couple the fluid and chemical domains, provides an integrated mechanochemical picture that potentially could help unveil mechanisms of ILT formation and development.
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| 5. |
- Jönsson, Maria, et al.
(författare)
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Foot centre of pressure and ground reaction force during quadriceps resistance exercises; a comparison between force plates and a pressure insole system.
- 2019
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Ingår i: Journal of Biomechanics. - : Elsevier BV. - 0021-9290 .- 1873-2380. ; 87, s. 206-210
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Tidskriftsartikel (refereegranskat)abstract
- The study compared the centre of pressure measurements (COP) and vertical ground reaction forces (vGRF) from a pressure insole system to that from force plates (FP) during two flywheel quadriceps resistance exercises: leg press and squat. The comparison was performed using a motion capture system and simultaneous measurements of COP and vGRF from FP and insoles. At lower insole-vGRF (<250 N/insole) COP accuracy deteriorated and those data were excluded from further analysis. The insoles systematically displaced the COP slightly posteriorly and medially compared to the FP measurements. Pearson's coefficient of correlation (r) between insole- and FP-COP showed good agreement in both the anteroposterior (squat: r = 0.96, leg press: r = 0.97) and mediolateral direction (squat: r = 0.84, leg press: r = 0.90), whereas the root-mean-square errors (RMSE) were lower in the mediolateral (squat: 3.9 mm, leg press: 4.5 mm) than the anteroposterior (squat and leg press: 11.8 mm) direction. Vertical GRF was slightly overestimated by the insoles in leg press and RMSE were greater in leg press (8% of peak force) than in squat (6%). Overall, results were within the range of previous studies performed on gait. The strong agreement between insole and FP measurements indicates that insoles may replace FPs in field applications and biomechanical computations during resistance exercise, provided that the applied force is sufficient.
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| 6. |
- Su, Binbin, et al.
(författare)
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Gait Phase Recognition Using Deep Convolutional Neural Network with Inertial Measurement Units
- 2020
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Ingår i: Biosensors. - : MDPI AG. - 2079-6374. ; 10:9, s. 109-109
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Tidskriftsartikel (refereegranskat)abstract
- Gait phase recognition is of great importance in the development of assistance-as-needed robotic devices, such as exoskeletons. In order for a powered exoskeleton with phase-based control to determine and provide proper assistance to the wearer during gait, the user’s current gait phase must first be identified accurately. Gait phase recognition can potentially be achieved through input from wearable sensors. Deep convolutional neural networks (DCNN) is a machine learning approach that is widely used in image recognition. User kinematics, measured from inertial measurement unit(IMU) output, can be considered as an ‘image’ since it exhibits some local ‘spatial’ pattern when the sensor data is arranged in sequence. We propose a specialized DCNN to distinguish five phases in a gait cycle, based on IMU data and classified with foot switch information. The DCNN showed approximately 97% accuracy during an offline evaluation of gait phase recognition. Accuracy was highest in the swing phase and lowest in terminal stance.
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| 7. |
- Su, Binbin, et al.
(författare)
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Gait Trajectory and Gait Phase Prediction Based on an LSTM Network
- 2020
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Ingår i: Sensors. - : MDPI AG. - 1424-8220. ; 20:24, s. 7127-7127
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Tidskriftsartikel (refereegranskat)abstract
- Lower body segment trajectory and gait phase prediction is crucial for the control of assistance-as-needed robotic devices, such as exoskeletons. In order for a powered exoskeleton with phase-based control to determine and provide proper assistance to the wearer during gait, we propose an approach to predict segment trajectories up to 200 ms ahead (angular velocity of the thigh, shank, and foot segments) and five gait phases (loading response, mid-stance, terminal stance, preswing, and swing), based on collected data from inertial measurement units placed on the thighs, shanks, and feet. The approach we propose is a long-short term memory (LSTM)-based network, a modified version of recurrent neural networks, which can learn order dependence in sequence prediction problems. The algorithm proposed has a weighted discount loss function that places more weight in predicting the next three to five time frames but also contributes to an overall prediction performance for up to 10 time frames. The LSTM model was designed to learn lower limb segment trajectories using training samples and was tested for generalization across participants. All predicted trajectories were strongly correlated with the measured trajectories, with correlation coefficients greater than 0.98. The proposed LSTM approach can also accurately predict the five gait phases, particularly the swing phase with 95% accuracy in inter-subject implementation. The ability of the LSTMnetwork to predict future gait trajectories and gait phases can be applied in designing exoskeleton controllers that can better compensate for system delays to smooth the transition between gait phases.
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| 8. |
- Su, Binbin, et al.
(författare)
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Locomotion Mode Transition Prediction Based on Gait-Event Identification Using Wearable Sensors and Multilayer Perceptrons
- 2021
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Ingår i: Sensors. - : MDPI AG. - 1424-8220. ; 21:22, s. 7473-
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Tidskriftsartikel (refereegranskat)abstract
- People walk on different types of terrain daily; for instance, level-ground walking, ramp and stair ascent and descent, and stepping over obstacles are common activities in daily life. Movement patterns change as people move from one terrain to another. The prediction of transitions between locomotion modes is important for developing assistive devices, such as exoskeletons, as the optimal assistive strategies may differ for different locomotion modes. The prediction of locomotion mode transitions is often accompanied by gait-event detection that provides important information during locomotion about critical events, such as foot contact (FC) and toe off (TO). In this study, we introduce a method to integrate locomotion mode prediction and gait-event identification into one machine learning framework, comprised of two multilayer perceptrons (MLP). Input features to the framework were from fused data from wearable sensors-specifically, electromyography sensors and inertial measurement units. The first MLP successfully identified FC and TO, FC events were identified accurately, and a small number of misclassifications only occurred near TO events. A small time difference (2.5 ms and -5.3 ms for FC and TO, respectively) was found between predicted and true gait events. The second MLP correctly identified walking, ramp ascent, and ramp descent transitions with the best aggregate accuracy of 96.3%, 90.1%, and 90.6%, respectively, with sufficient prediction time prior to the critical events. The models in this study demonstrate high accuracy in predicting transitions between different locomotion modes in the same side's mid- to late stance of the stride prior to the step into the new mode using data from EMG and IMU sensors. Our results may help assistive devices achieve smooth and seamless transitions in different locomotion modes for those with motor disorders.
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| 9. |
- Olson, Linus, et al.
(författare)
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Phase-Changing Glauber Salt Solution for Medical Applications in the 28-32 degrees C Interval
- 2021
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Ingår i: Materials. - : MDPI AG. - 1996-1944. ; 14:23
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Tidskriftsartikel (refereegranskat)abstract
- (1) Background: The field of medicine requires simple cooling materials. However, there is little knowledge documented about phase change materials (PCM) covering the range of 28 to 40 degrees Celsius, as needed for medical use. Induced mild hypothermia, started within 6 h after birth, is an emerging therapy for reducing death and severe disabilities in asphyxiated infants. Currently, this hypothermia is accomplished with equipment that needs a power source and a liquid supply. Neonatal cooling is more frequent in low-resource settings, where ~1 million deaths are caused by birth-asphyxia. (2) Methods: A simple and safe cooling method suitable for medical application is needed for the 28 to 37.5 degrees C window. (3) Results: Using empirical experiments in which the ingredients in Glauber salt were changed, we studied the effects of temperature on material in the indicated temperature range. The examination, in a controlled manner, of different mixtures of NaCl, Na2SO4 and water resulted in a better understanding of how the different mixtures act and how to compose salt solutions that can satisfy clinical cooling specifications. (4) Conclusions: Our Glauber salt solution is a clinically suited PCM in the temperature interval needed for the cooling of infants suffering from asphyxia.
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| 10. |
- Davidsson, Johan, 1967, et al.
(författare)
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Characterisation of the pressure distribution in penetrating traumatic brain injuries
- 2015
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Ingår i: Frontiers in Neurology. - : Frontiers Media SA. - 1664-2295. ; 6:51, s. 1-12
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Tidskriftsartikel (refereegranskat)abstract
- Severe impacts to the head commonly lead to localized brain damage. Such impacts may also give rise to temporary pressure changes that produce secondary injuries in brain volumes distal to the impact site. Monitoring pressure changes in a clinical setting is difficult; detailed studies into the effect of pressure changes in the brain call for the development and use of animal models.The aim of this study is to characterize the pressure distributionin an animal model of penetrating traumatic brain injuries (pTBI). This data may be used to validate mathematical models of the animal model and to facilitate correlation studies between pressure changes and pathology. Pressure changes were measured in rat brains while subjected to pTBI for a variety of different probe velocities and shapes; pointy, blunt, and flat. Experiments on ballistic gel samples were carried out to study the formation of any temporary cavities. In addition, pressure recordings from the gel experiments were compared to values recorded in the animal experiments. The pTBI generated short lasting pressure changes in the brain tissue; the pressure in the contralateral ventricle (CLV) increased to 8 bar followed by a drop to 0.4 bar when applying flat probes. The pressurechanges in the periphery of the probe, in the Cisterna Magna, and the spinal canal, were significantly less than those recorded in the CLV or the vicinity of the skull base. Highspeed videos of the gel samples revealed the formation of spherically shaped cavities when flat and spherical probes were applied. Pressure changes in the gel were similar to those recorded in the animals, although amplitudes were lower in the gel samples. We concluded cavity expansion rate rather than cavity size correlated with pressure changes in the gel or brain secondary to probe impact. The new data can serve as validation datafor finite element models of the trauma model and the animal and to correlate physical measurements with secondary injuries.
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