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  • 201. Bernard, Olivier
    et al.
    Bosch, J G
    Heyde, Brecht
    Alessandrini, Martino
    Barbosa, Daniel
    Camarasu-Pop, S
    Cervenansky, F
    Valette, S
    Mirea, O
    Bernier, M
    Jodoin, P M
    Domingos, J S
    Stebbing, R V
    Keraudren, K
    Oktay, O
    Caballero, J
    Shi, W
    Rueckert, D
    Milletari, F
    Ahmadi, S A
    Smistad, E
    Lindseth, F
    van Stralen, M
    Wang, Chunliang
    KTH, School of Technology and Health (STH), Medical Engineering, Medical Image Processing and Visualization.
    Smedby, Örjan
    KTH, School of Technology and Health (STH), Medical Engineering, Medical Image Processing and Visualization.
    Donal, E
    Monaghan, M
    Papachristidis, A
    Geleijnse, M L
    Galli, E
    Dhooge, Jan
    Standardized evaluation system for left ventricular segmentation algorithms in 3D echocardiography.2015In: IEEE Transactions on Medical Imaging, ISSN 0278-0062, E-ISSN 1558-254XArticle in journal (Refereed)
    Abstract [en]

    Real-time 3D Echocardiography (RT3DE) has been proven to be an accurate tool for left ventricular (LV) volume assessment. However, identification of the LV endocardium remains a challenging task, mainly because of the low tissue/blood contrast of the images combined with typical artifacts. Several semi and fully automatic algorithms have been proposed for segmenting the endocardium in RT3DE data in order to extract relevant clinical indices, but a systematic and fair comparison between such methods has so far been impossible due to the lack of a publicly available common database. Here, we introduce a standardized evaluation framework to reliably evaluate and compare the performance of the algorithms developed to segment the LV border in RT3DE. A database consisting of 45 multivendor cardiac ultrasound recordings acquired at different centers with corresponding reference measurements from 3 experts are made available. The algorithms from nine research groups were quantitatively evaluated and compared using the proposed online platform. The results showed that the best methods produce promising results with respect to the experts' measurements for the extraction of clinical indices, and that they offer good segmentation precision in terms of mean distance error in the context of the experts' variability range. The platform remains open for new submissions.

  • 202.
    Berndtsson, Andreas
    KTH, School of Technology and Health (STH), Medical Engineering.
    Heart Rate Variability Biofeedback for Android2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Heart rate variability (HRV) is the variations in time between consecutive heart beats, and reflects the functioning of the autonomic nervous system. Not only is HRV a good marker for many physiological disorders, but it is well known that HRV can be altered consciously by different approaches even though it is controlled by the autonomic nervous system. Respiration is an important factor in modulating HRV and this property is utilized in HRV biofeedback, which is a method that aims at increasing heart rate variability. HRV biofeedback systems typically measures heart rate variability and display the parameters on a screen, enabling the user to gain control and increase heart rate variations. In this thesis a software for biofeedback of heart rate variability is presented. The software was implemented for Android and runs on a tablet computer to make the biofeedback system portable and more accessible than most other biofeedback systems. The developed software has proven to be fully functional in real-time providing the user with reliable information. A small pilot study on healthy volunteers has also been made to evaluate the effects of the biofeedback training. These measurements give a preliminary indication that biofeedback session with the proposed solution increases HRV. However, a more comprehensive study with a larger population needs to be carried out in order to confidently confirm the positive effects of biofeedback sessions with the software. 

  • 203.
    Beskow, Tua
    KTH, School of Technology and Health (STH).
    Hip impact of the FE-model THUMS: Model adaptation and validation followed by an evaluation of the KTH developed shock absorbing floor system2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Abstract

    Fall accidents leads to an average of three deaths a day in Sweden. The high mortality and morbidity associated with falls among elderly is due to a high risk of falling caused by impaired mobility, sight and balance in combination with increased vulnerability as a result of fragile bones as well as comorbid conditions. Researchers at the department of Neuronics at KTH has developed a shock-absorbing floor that aim to reduce the risk of fall related fractures. The floors has shown promising results in mechanical drop tests but requires further analysis before it can be implemented in retirement homes.

    The goal of this master thesis is to refine, adapt and validate the finite element model THUMS 4.02 for fall simulations. The model will then be used to analyze the shock absorbing ability of various floor systems. Model adaptations included modification of the material properties of the adipose tissue and cartilage in the hips and implantation of tied internal contacts. Validation was performed against data from two experimental studies selected in a literature study, dynamic impact with isolated pelvis and lateral hip impact of complete PMHS.

    The experimental setups were reproduced in LS-Dyna and relatively close agreement for the force curves could be displayed in both cases. The model also showed realistic force response for fall simulations and a force reduction with up to 23% in simulation to the KTH developed floor system, differences could be seen for different fall positions of the model. Fall simulations agreed well with clinically and scientifically documented fracture loads and patterns. Further studies needs to be performed to further validate the model and analyze effect of different geometrical properties of floor system.

  • 204.
    Bhuddi, Amita
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Somos, Oliver
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Återställningsverktyg för fordon baserat på applikationsintegration2016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The software testing team at Scania use a manual and time consuming process to restore a test vehicle after working with it. Several different applications are used in this process to ensure the vehicle is in the same state as it was before their testing. To improve the workflow with a reduced workload and a more robust process, the test team was interested in the development of a restoration application. It was desired to develop the restoration application by reusing the components to the greatest possible extend. Since there were many components that fulfilled the needs of most functions, a pre-study of all the applications was done to decide which components can be re-used. This was study was based on the integration model, Enterprise Application Integration, which aims to create a single product combining the applications used in an organization to simplify processes such as maintenance, data management and employee training. A prototype was developed which implements three existing modules on different levels and, in line with the goals of EAI, is itself a simple application that enables the components to work in unision

  • 205.
    Birgisson, Björn
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Sjölander, Peta White
    KTH, School of Technology and Health (STH), Health Systems Engineering, Ergonomics.
    Snickars, Folke
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Urban and Regional Studies.
    Kjellberg, Peter
    KTH.
    Perhson, Susanna
    KTH.
    Eriksson, Thomas
    KTH.
    Reitberger, Göran
    KTH.
    RAE2012: KTH Research Assessment Exercise 20122012Book (Other (popular science, discussion, etc.))
  • 206.
    Bjering, Beatrice
    et al.
    KTH, School of Technology and Health (STH).
    Forss, Elin
    KTH, School of Technology and Health (STH).
    Videoanalys av sekvenser i ishockey där en tackling resulterat i hjärnskakning2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    There is a major issue with concussion within contact sports and one of these sports is ice hockey. Concussions have a negative effect on health and repeated concussions, which often occur in ice hockey, can force players to retire early. Since it is such a major problem that can result in serious consequences, a better understanding within the field is needed. This report has focused on speeds right before a player was tackled as well as the players contact body parts. The information was collected by analyzing 10 video clips where a tackle took place that resulted in a concussion. The video clips were analyzed using the software SkillSpector, where 3D speeds were collected for both the attacking and the injured players. The contact body parts were also identified during the analysis. The results were compared to a reference group from an earlier bachelor degree project where tackles that did not result in a concussion were analyzed. The conclusion from this project is that the speeds for the players in the interest group were proven to have a significantly higher mean speed than the players from the earlier project. Furthermore, the results indicate that the tackled players speed can have a larger impact on the outcome of the tackle than the speed of the attacking player. From the results in this project it is shown that, of the tackles that could lead to a concussion, shoulder to jaw was the most common combination.

  • 207. Bjorkander, Inge
    et al.
    Forslund, Lennart
    Kahan, Thomas
    Ericson, Mats
    KTH, School of Technology and Health (STH), Ergonomics (Closed 20130701).
    Held, Claes
    Rehnqvist, Nina
    Hjemdahl, Paul
    Differential index: a simple time domain heart rate variability analysis with prognostic implications in stable angina pectoris2008In: Cardiology, ISSN 0008-6312, E-ISSN 1421-9751, Vol. 111, no 2, p. 126-133Article in journal (Refereed)
    Abstract [en]

    OBJECTIVES: To examine the usefulness of time domain heart rate variability (HRV) measurements by a simple graphical method, the differential index (DI), in prognostic assessments of patients with chronic stable angina pectoris.

    METHODS: HRV measurements in the time domain by DI were compared to conventional measurements of standard deviation of all normal-to-normal intervals (SDNN), percent of differences between adjacent normal RR intervals >50 ms (PNN50) and square root of the mean of the sum of squares of differences between adjacent normal RR intervals (RMSSD) from 24-hour ambulatory electrocardiographic recordings in 678 patients in the Angina Prognosis Study in Stockholm. The patients received double-blind treatment with metoprolol or verapamil. Main outcome measures were cardiovascular death or non-fatal myocardial infarction during follow-up (median 40 months).

    RESULTS: Patients suffering cardiovascular death (n = 30) had lower DI, SDNN and PNN50 (all p < 0.001). In a multivariate Cox model, DI below median independently predicted cardiovascular death (p = 0.002), as did SDNN (p = 0.016) and PNN50 (p = 0.030), but not RMSSD (p = 0.10). The separation of survival curves was most pronounced and specificity was slightly better with DI. DI and PNN50 increased with metoprolol but not verapamil treatment. Short-term treatment effects were not related to prognosis.

    CONCLUSIONS: Low time domain HRV carries independent prognostic information regarding cardiovascular death in stable angina pectoris. The simple DI method provided equally good or better prognostic information than conventional, more laborious HRV methods.

  • 208.
    Bjällmark, Anna
    KTH, School of Technology and Health (STH), Medical Engineering.
    New ultrasonographic approaches to monitoring cardiac and vascular function2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Atherosclerotic cardiovascular disease is the leading cause of death worldwide. To decrease mortality and morbidity in cardiovascular disease, the development of accurate, non-invasive methods for early diagnosis of atherosclerotic cardiac and vascular engagement is of considerable clinical interest. Cardiovascular ultrasound imaging is today the cornerstone in the routine evaluation of cardiovascular function and recent development has resulted in two new techniques, tissue velocity imaging (TVI) and speckle tracking, which allow objective quantification of cardiovascular function. TVI and speckle tracking are the basis for three new approaches to cardiac and vascular monitoring presented in this thesis: wave intensity wall analysis (WIWA), two-dimensional strain imaging in the common carotid artery, and the state diagram of the heart.

     

    WIWA uses longitudinal and radial strain rate as input for calculations of wave intensity in the arterial wall. In this thesis, WIWA was validated against a commercially available wave intensity system, showing that speckle tracking-derived strain variables can be useful in wave intensity analysis. WIWA was further tested in patients with end stage renal disease and documented high mortality in cardiovascular disease. The latter study evaluated the effects of a single session of hemodialysis using WIWA and TVI variables and showed improved systolic function after hemodialysis. The results also indicated that preload-adjusted early systolic wave intensity obtained by the WIWA system may contribute in the assessment of left ventricular contractility in this patient category. Two-dimensional strain imaging in the common carotid artery is a new approach showing great potential to detect age-dependent differences in mechanical properties of the common carotid artery. Among the measured strain variables, global circumferential strain had the best discriminating performance and appeared to be superior to conventional measures of arterial stiffness such as elastic modulus and β stiffness index. The state diagram is a visualisation tool that provides a quantitative overview of the temporal interrelationship of mechanical events in the left and right ventricles. Case examples and a small clinical study showed that state diagrams clearly visualize cardiac function and can be useful in the detection of non ST-elevation myocardial infarction (NSTEMI).

     

    Even though WIWA, two-dimensional strain imaging in the common carotid artery and the state diagram show potential to be useful in the evaluation of cardiovascular function, there still remains a considerable amount of work to be done before they can be used in the daily clinical practice.

  • 209.
    Bjällmark, Anna
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering.
    Gustafsson, U
    Brodin, Lars-Åke
    KTH, School of Technology and Health (STH), Medical Engineering.
    Waldenström, A
    Larsson, Matilda
    KTH, School of Technology and Health (STH), Medical Engineering.
    A system to quantify and visualize ventricular rotation pattern of the heart2009Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    Different modalities have been used to describe the rotational motion of the ventricles of the heart and studies have indicated LV twist to be an additional integral component in LV function. So far, only amplitudes and timings of rotation have been reported, whereas no method is available to fully describe the rotation pattern of the ventricles. The object of the present application is to achieve a system that presents a novel way to quantify and visualize the ventricular rotation pattern of the heart. We present a novel method that assesses and describes the rotation pattern by calculating the rotation axis of the ventricle. Non- invasive image acquisition is required to collect rotation values from different positions of the myocardium. Thereafter, a kinematic model of a ventricle is constructed to determine the rotation planes at different levels of the heart. The motion of the rotation planes are visualized by plotting the normal vectors of the planes over time, i.e. the rotation axis of the planes. This new method is different to all other methods used today for assessing cardiac function, as it does not describe the amplitude of a motion but the relationship in motion between different parts within a ventricle. Preliminary results indicate that the rotation axis is more sensitive to changes in the rotation pattern than conventional measurements of ventricular rotation. This new method could be used for early detection of cardiac diseases and for selection of patients for and optimization of cardiac resynchronization therapy.

  • 210.
    Bjällmark, Anna
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering.
    Larsson, Matilda
    KTH, School of Technology and Health (STH), Medical Engineering.
    Brodin, Lars-Åke
    KTH, School of Technology and Health (STH), Medical Engineering.
    Nowak, Jacek
    Lind, Britta
    KTH, School of Technology and Health (STH), Medical Engineering.
    Hayashi, Shirley
    Mazza do Nascimento, Marcelo
    Riella, Miquel
    Seeberger, Astrid
    Effects of hemodialysis on the cardiovascular system: Quantitative analysis using wave intensity wall analysis and tissue velocity imaging2010In: Heart and Vessels, ISSN 0910-8327, E-ISSN 1615-2573Article in journal (Refereed)
    Abstract [en]

    Cardiovascular disease is the leading cause of death in patients with end stage renal disease (ESRD). The aim of this study was to investigate the changes in cardiovascular function induced by a single session of hemodialysis (HD) by the analysis of cardiovascular dynamics using wave intensity wall analysis (WIWA) and of systolic and diastolic myocardial function using tissue velocity imaging (TVI). Grey-scale cine loops of the left common carotid artery, conventional echocardiography and TVI images of the left ventricle were acquired before and after HD in 45 patients (17 women, mean age 54) with ESRD. The WIWA indexes, W1 preload-adjusted W1, W2 and preload-adjusted W2, and the TVI variables, isovolumic contraction velocity (IVCV), isovolumic contraction time (IVCT), peak systolic velocity (PSV), displacement, isovolumic relaxation velocity (IVRV), isovolumic relaxation time (IVRT), peak early diastolic velocity (E’) and peak late diastolic velocity (A’), were compared before and after HD. The WIWA measurements showed significant increases in W1 (p < 0.05) and preload-adjusted W1 (p < 0.01) after HD. W2 was significantly decreased (p < 0.05) after HD, whereas the change in preload-adjusted W2 was not significant. Systolic velocities, IVCV (p < 0.001) and PSV (p < 0.01), were increased after HD, whereas the AV-plane displacement were decreased (p < 0.01). For the measured diastolic variables, E’ was significantly decreased (p < 0.01) and IVRT was significantly prolonged (p < 0.05), after HD. A few correlations were found between WIWA and TVI variables. The WIWA and TVI measurements indicate that a single session of HD improves systolic function. The load dependency of the diastolic variables seems to be more pronounced than for the systolic variables. Preload-adjusted wave intensity indexes may contribute in the assessment of true LV contractility and relaxation.

  • 211.
    Bjällmark, Anna
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering.
    Larsson, Matilda
    KTH, School of Technology and Health (STH), Medical Engineering.
    Lind, Britta
    KTH, School of Technology and Health (STH), Medical Engineering.
    Brodin, Lars-Åke
    KTH, School of Technology and Health (STH), Medical Engineering.
    Winter, Reidar
    Westholm, Carl
    Jacobsen, Per
    Velocity tracking - a novel method for quantitative analysis of longitudinal myocardial function2007In: Journal of the American Society of Echocardiography, ISSN 0894-7317, E-ISSN 1097-6795, Vol. 20, no 7, p. 847-856Article in journal (Refereed)
    Abstract [en]

    Doppler tissue imaging is a method for quantitative analysis of longitudinal myocardial velocity. Commercially available ultrasound systems can only present velocity information using a color Dopplerbased overlapping continuous color scale. The analysis is time-consuming and does not allow for simultaneous analysis in different projections. We have developed a new method, velocity tracking, using a stepwise color coding of the regional longitudinal myocardial velocity. The velocity data from 3 apical projections are presented as static and dynamic bull's-eye plots to give a 3-dimensional understanding of the function of the left ventricle. The static bull's-eye plot can display peak systolic velocity, late diastofic tissue velocity, or the sum of peak systolic velocity and early diastolic tissue velocity. Conversely, the dynamic bull's-eye plot displays how the myocardial velocities change over one heart cycle. Velocity tracking allows for a fast, simple, and hituitive visual analysis of the regional longitudinal contraction pattern of the left ventricle with a great potential to identify characteristic pathologic patterns.

  • 212.
    Bjällmark, Anna
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering.
    Larsson, Matilda
    KTH, School of Technology and Health (STH), Medical Engineering.
    Shahgaldi, Kambiz
    Lind, Britta
    KTH, School of Technology and Health (STH).
    Winter, Reidar
    Brodin, Lars-Ake
    KTH, School of Technology and Health (STH), Medical Engineering.
    Differences in myocardial velocities during supine and upright exercise stress echocardiography in healthy adults2009In: Clinical Physiology and Functional Imaging, ISSN 1475-0961, E-ISSN 1475-097X, Vol. 29, no 3, p. 216-223Article in journal (Refereed)
    Abstract [en]

    Tissue Velocity Imaging (TVI) is a method for quantitative analysis of longitudinal myocardial velocities, which can be used during exercise and pharmacological stress echocardiography. It is of interest to evaluate cardiac response to different types of stress tests and the differences between upright and supine bicycle exercise tests have not been fully investigated. Therefore, the aim of this study was to compare cardiac response during supine and upright exercise stress tests. Twenty young healthy individuals underwent supine and upright stress test. The initial workload was set to 30 W and was increased every minute by a further 30 W until physical exhaustion. Tissue Doppler data from the left ventricle were acquired at the end of every workload level using a GE Vivid7 Dimension system (> 200 frames s(-1)). In the off-line processing, isovolumic contraction velocity (IVCV), peak systolic velocity (PSV), isovolumic relaxation velocity (IVRV), peak early diastolic velocity (E') and peak late diastolic velocity (A') were identified at every workload level. No significant difference between the tests was found in PSV. On the contrary, E' was shown to be significantly higher (P < 0.001) during supine exercise than during upright exercise and IVRV was significantly lower (P < 0.001) during supine exercise compared to upright exercise. Upright and supine exercise stress echocardiography give a comparable increase in measured systolic velocities and significant differences in early diastolic velocities.

  • 213.
    Bjällmark, Anna
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering.
    Lind, Britta
    KTH, School of Technology and Health (STH), Medical Engineering.
    Brodin, Lars-Åke
    KTH, School of Technology and Health (STH), Medical Engineering.
    Peolsson, Michael
    KTH, School of Technology and Health (STH).
    Shahgaldi, Kambiz
    KTH, School of Technology and Health (STH), Medical Engineering.
    Nowak, Jacek
    Ultrasonographic strain imaging is superior to conventional non-invasive measures of vascular stiffness in the detection of age-dependent differences in the mechanical properties of the common carotid artery2010In: European Journal of Echocardiography, ISSN 1525-2167, E-ISSN 1532-2114, Vol. 11, no 7, p. 630-636Article in journal (Refereed)
    Abstract [en]

    Aims: Elastic properties of large arteries have been shown to deteriorate with age and in the presence of atherosclerotic vascular disease. In this study, the performance of ultrasonographic strain measurements was compared to conventional measures of vascular stiffness in the detection of age-dependent differences in the elastic properties of the common carotid artery.

    Methods and results: In 10 younger (25-28 years, 4 women) and 10 older (50-59 years, 4 women) healthy individuals, global and regional circumferential and radial strain variables were measured in the short-axis view of the right common carotid artery using ultrasonographic two-dimensional (2D) strain imaging with recently introduced speckle tracking technique. Conventional elasticity variables, elastic modulus (Ep) and β stiffness index, were calculated using M-mode sonography and non-invasive blood pressure measurements. Global and regional circumferential systolic strain and strain rate values were significantly higher (p < 0.001, p < 0.01 for regional late systolic strain rate) in the younger individuals, whereas the values of conventional elasticity variables in the same group were lower (p < 0.05). Among all strain and conventional elasticity variables, principal component analysis and its regression extension identified only circumferential systolic strain variables as contributing significantly to the observed discrimination between the younger and older age groups.

    Conclusion: Ultrasonographic 2D-strain imaging is a sensitive method for the assessment of elastic properties in the common carotid artery, being in this respect superior to conventional measures of vascular elasticity. The method has potential to become a valuable non-invasive tool in the detection of early atherosclerotic vascular changes.

  • 214. Björk, Mathilda
    et al.
    Gerdle, Björn
    Thyberg, Ingrid
    Peolsson, Michael
    KTH, School of Technology and Health (STH), Centres, Centre for Technology in Medicine and Health, CTMH.
    Multivariate relationships between pain intensity and other aspects of health in rheumatoid arthritis - cross sectional and five year longitudinal analyses (the Swedish TIRA project)2008In: Disability and Rehabilitation, ISSN 0963-8288, E-ISSN 1464-5165, Vol. 30, no 19, p. 1429-1438Article in journal (Refereed)
    Abstract [en]

    Objectives. This study analyses the relationships between pain intensity and other aspects of health commonly used to assess disease activity and disability in early rheumatoid arthritis and examines whether such relationships were different between women and men. Subjects and methods. This study included the 189 patients (69% women) with early RA (symptoms < 12 months at diagnosis) still remaining in the Swedish TIRA cohort 5 years after inclusion. Disease activity and disability was assessed 3, 6, 12, 18, 24, 36, 48, and 60 months (M0-M60) after inclusion by erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), number of swollen and tender joints, physicians global assessment of disease activity (PGA), grip force average over 10 seconds (Grippit), Grip Ability Test (GAT), Signals of Functional Impairment (SOFI) in hand, lower limb and upper limb, Health Assessment Questionnaire (HAQ), and pain intensity measured with a visual analogue scale (VAS). The variables were divided into meaningful blocks according to the correlation structure in a principal component analysis (PCA) at M60. Using hierarchical partial least squares (PLS) analyses, this study investigated the blocks cross-sectionally to test for correlations with pain intensity at M0 and M60. The blocks at M0 were also used as predictors of pain intensity at M60 in a hierarchical PLS. Results. The strongest relationship was found between pain intensity and the second block, consisting of HAQ and SOFI-lower limb at the cross-sectional analyses in both women and men. The block representing disease activity (i.e., ESR, CRP, PGA, and swollen and tender joints) had the weakest relation to pain intensity. According to the longitudinal analyses, the disease activity variables (block 1) at M0 had the strongest relationship to pain intensity at M60 in men. In contrast, HAQ and SOFI-lower limb (block 2) at M0 had a strong relation to pain intensity in women.

  • 215. Björkander, I.
    et al.
    Kahan, T.
    Ericson, Mats
    KTH, School of Technology and Health (STH), Ergonomics (Closed 20130701).
    Held, C.
    Forslund, L.
    Rehnqvist, N.
    Hjemdahl, P.
    Differential index, a novel graphical method for measurements of heart rate variability2005In: International Journal of Cardiology, ISSN 0167-5273, E-ISSN 1874-1754, Vol. 98, no 3, p. 493-499Article in journal (Refereed)
    Abstract [en]

    Background: Commonly used methods to evaluate heart rate variability require extensive filtering of the registrations in order to exclude artefacts and ectopic beats. We developed and validated a novel graphical method for time-domain measurements of heart rate variability, the differential index, which does not require filtering and is simple to use. Methods: The 24-h ambulatory long-term electrocardiogram recordings from 120 patients with angina pectoris and 49 control subjects were computerised without any filtering process. Sample density histograms of differences in the RR interval for successive beats were constructed and the widths of the histograms were used to obtain the differential index. For comparison, the same registrations were analysed by conventional methods. Results: The differential index was most closely related (P < 0.001) to conventional short-term time domain (e.g. percent of differences between adjacent normal RR intervals > 50 ms, pNN50, r = 0.81) and frequency-domain (e.g. high frequency power, r = 0.84) components, but also to long-term time domain (e.g. standard deviation of all normal-to-normal RR intervals for all 5-min segments of the entire registration, SDNNIDX, r = 0.72) and frequency-domain (e.g. low frequency power, r = 0.64) components. Conclusion: The differential index method shows good agreement with established indices of heart rate variability. The insensitivity to recording artefacts and short-lasting disturbances of sinus rhythm make the differential index method particularly suited when data quality is imperfect. The simplicity of the method is valuable when large numbers of registrations are to be evaluated.

  • 216.
    Björklund, Johan
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Prestandautvärdering av permanentmagnetmotor2014Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The project was to evaluate a synchronous three-phase permanent magnet motor with brushless outrunner. It is supposed to be a part of an electric drive system for equipment onboard sailing boats. The goal was to investigate the performance of the motor and find the construction weaknesses and to come up with suggestions how to optimize the performance of the motor.

     

    Tests and measurements were made with a test setup that consisted of inverter, motor and a generator connected to the shaft. The generator stator winding had a short circuit when the load current reached 106,1 A and the tests therefore had to end. The copper wire used in the windings temperature became to high and the isolation of the wire melted.  The tests showed that the motor could handle up to 92,1 A with an efficiency of 70%. It was how much current the winding could withstand together with the power losses that was the limiting factor of the motor construction.

     

    Forced cooling with water cooled stator or improving the winding wires ability to handle higher currents by increasing the cable area are both alternatives to get a better efficiency and motor performance.

  • 217.
    Björklund, Tomas
    KTH, School of Technology and Health (STH).
    Automatic evaluation of breast density in mammographic images2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The goal of this master thesis is to develop a computerized method for automatic estimation of the mammographic density of mammographic images from 5 different types of mammography units.

     

    Mammographic density is a measurement of the amount of fibroglandular tissue in a breast. This is the single most attributable risk factor for breast cancer; an accurate measurement of the mammographic density can increase the accuracy of cancer prediction in mammography. Today it is commonly estimated through visual inspection by a radiologist, which is subjective and results in inter-reader variation.

     

    The developed method estimates the density as a ratio of #pixels-containing-dense-tissue over #pixels-containing-any-breast-tissue and also according to the BI-RADS density categories. To achieve this, each mammographic image is:

    • corrected for breast thickness and normalized such that some global threshold can separate dense and non-dense tissue.
    • iteratively thresholded until a good threshold is found.  This process is monitored and automatically stopped by a classifier which is trained on sample segmentations using features based on different image intensity characteristics in specified image regions.
    • filtered to remove noise such as blood vessels from the segmentation.
    • Finally, the ratio of dense tissue is calculated and a BI-RADS density class is assigned based on a calibrated scale (after averaging the ratings of both craniocaudal images for each patient). The calibration is based on resulting density ratio estimations of over 1300 training samples against ratings by radiologists of the same images.

     

    The method was tested on craniocaudal images (not included in the training process) acquired with different mammography units of 703 patients which had also been rated by radiologists according to the BI-RADS density classes. The agreement with the radiologist rating in terms of Cohen’s weighted kappa is substantial (0.73). In 68% of the cases the agreement is exact, only in 1.2% of the cases the disagreement is more than 1 class.

  • 218.
    Björkman, Daniel
    et al.
    KTH, School of Technology and Health (STH).
    Lundgren, Daniel
    Spårning av skelettala strukturer på 4D-CT2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The technical development of computed tomography (CT) with faster image collection frequencies and lower radiation dose while maintaining or increasing spatial and tissue-specific resolution, has enabled timeresoluted dynamic CT for the study of body parts in motion.

     

    The development of this technology has come to the attention of the supervisors at the Karolinska Institute and the Royal Institute of Technology. They were interested to investigate the possibility of using today´s technology to calculate the kinematics of skeletal foot segments, based on a dynamic CT collection of a human foot. Thus a method to detect, extract and track landmarks in sequences of 3-dimensional (3D) volumes, and the description of foot kinematics during plantarflexion and dorsiflexion was developed in this thesis.

     

    The developed method intended to automatically track skeletal foot segments and calculate their relative movement and rotation in the frontal, sagittal and transverse plane. A program was developed using commercially available software that isolated a selected skeletal segment and detected its landmarks. The automatic landmark detection useful for tracking needs further development and therefore complementary manual detection was performed. These landmarks were used to calculate the kinematics by tracking individually created local coordinate system for each structure. As an example the maximum rotation stated between calcaneus and talus was 51 degrees within the sagittal plane. The thesis illustrates methods used and presents the developed program and all the results of the individual and relative motion of the calcaneus and talus. The method used in this thesis has a good future potential with possibilities to visualize and calculate normal and pathological musculoskeletal motion.

  • 219.
    Björkvall, Dennis
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Ploug, Martin
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Metod för automatiserad sammanfattning och nyckelordsgenerering2016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The company Widespace handles hundreds of tasks (tickets) per week, which requires great overview by each employee. Because of this quantity, creating a clear view becomes a major problem. To solve this problem, a more consistent use of metadata is required, therefore, a study of metadata, automated summary and key words generation has been performed.

    The task was to develop a prototype that can automatically generate a summary, a list of keywords and give an indication of what language the text is written in. It was also included in the work to make a survey of earlier works to see which systems and methods that can be used for this task. Two prototypes were developed, compared with each other and evaluated. The methods used were based on both statistical and linguistic processes. Analysis of the results was done and showed that the prototype MkOne delivered the best results for the summary. The keyword list contained many precise keywords with high precision and a wide coverage.

  • 220.
    Björnström, Tommie
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Cederqvist, Reidar
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Comparison and Implementation of Software Frameworks for Internet of Things2015Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    There is no established standard for how Internet of Things devices are communicating with each other, every manufacturer uses their own proprietary software and protocols. This makes it difficult to ensure the best possible user experience. There are several projects that can become a standard for how devices discovering, communicating, networking etc. The goal for this thesis work was to compare such software frameworks in some areas and investigate how Inteno’s operating system Iopsys OS can be complemented by implement one of these frameworks. A literature study gave two candidates for the comparison, AllJoyn and Bonjour. The result of the comparison showed that AllJoyn was the most appropriate choice for Inteno to implement into their OS. AllJoyn was chosen because it has a potential to become an established standard and includes tools for easy implementation. To make a proof of concept, an AllJoyn application was created. The application together with a JavaScript web page, can show and control options for an AllJoyn Wi-Fi manager application and AllJoyn enabled lamps.

  • 221. Blogg, L
    et al.
    Gennser, Mikael
    KTH, School of Technology and Health (STH), Basic Science and Biomedicine, Environmental Physiology.
    Arterial bubbles following trimix dives2014Conference paper (Other academic)
  • 222. Blogg, L
    et al.
    Gennser, Mikael
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Direct comparison of audio Doppler ultrasound scores and 2D ultrasound images of venous gas emboli.2010Conference paper (Refereed)
  • 223. Blogg, L
    et al.
    Gennser, Mikael
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Near maximal venous bubble scores and arterial bubbles with no signs or symptoms of DCS - a case study.2011Conference paper (Refereed)
  • 224. Blogg, L
    et al.
    Gennser, Mikael
    KTH, School of Technology and Health (STH), Basic Science and Biomedicine, Environmental Physiology.
    Predisponerar helium i dykgasen för arteriella bubblor?2014Conference paper (Other academic)
    Abstract [sv]

    Bakgrund: Bubblor i den arteriella cirkulationen observerades första gången vid 10 av 12 exkursioner från heliox- (O2/He) och trimix- (O2/He/N2) mättnad (1).  På senare tid har Ljukovic et al (2) redovisat resultat av trimixdykningar där 5 av 7 dykare uppvisade arteriella bubblor. Visserligen har arteriella bubblor observerats även i samband med nitrox- och luftdykningar men inte i så hög frekvens. Gör heliumgasen att bubblor lättare tar sig igenom lungfiltret?

    Metoder: Dykare undersöktes med kardiellt ekokardiografi efter 251 trimixdykningar och 37 nitroxdykningar med varierande dykprofiler. Dykdjupen varierade mellan 20 – 100 m för trimixdykningarna och 33 – 60 m för nitroxdykningarna. Totalt 43 dykare deltog i trimix- och 19 dykare i nitroxdykningarna. Dykarna undersöktes varje kvart i 2 timmar efter dykningarna. Förekomst av venösa och arteriella bubblor registrerades och skattades enligt Brubakk-Eftedal-skalan (EB).

    Resultat: Totalt observerades arteriella bubblor hos 3/43 dykare efter trimixdykning och hos 3/19 dykare efter nitroxdykning. En av dykarna med arteriella bubblor i nitroxgruppen behandlades för ledbends. Två av dykarna hade arteriella bubblor både efter trimix- och nitroxdykningar. I samtliga fall med artärbubblor observerades också venösa bubblor (EB 2 – 4c).

    Slutsats: Jämfört med tidigare rapporterad incidens av artärbubblor i samband med trimixdykningar är de redovisade resultaten låga. Resultaten för nitroxdykningarna är också låga givet att ca 25% av normalpopulationen har öppetstående foramen ovale. Någon ökad incidens artärbubblor observerades inte med den heliuminnehållande gasen, utan det mest troliga är att förekomsten av artärbubblor beror på mängden venösa bubblor och individuell predisponering att ”läcka” bubblor från den venösa till den arteriella cirkulationen.

  • 225. Blogg, L
    et al.
    Gennser, Mikael
    KTH, School of Technology and Health (STH), Basic Science and Biomedicine, Environmental Physiology.
    Jurd, KM
    Møllerløkken, A
    Observed incidence of decompression sickness and venous gas bubbles following 18 M dives on RN table 11/Norwegian air diving table2015Conference paper (Refereed)
  • 226. Blogg, S. Lesley
    et al.
    Gennser, Mikael
    KTH, School of Technology and Health (STH), Environmental Physiology.
    The need for optimisation of post-dive ultrasound monitoring to properly evaluate the evolution of venous gas emboli2011In: Diving and hyperbaric medicine : the journal of the South Pacific Underwater Medicine Society, ISSN 1833-3516, Vol. 41, no 3, p. 139-146Article in journal (Refereed)
    Abstract [en]

    Audio Doppler ultrasound and echocardiographic techniques are useful tools for investigating the formation of inert gas bubbles after hyperbaric exposure and can help to assess the risk of occurrence of decompression sickness. However, techniques, measurement period and regularity of measurements must be standardised for results to be comparable across research groups and to be of any benefit. There now appears to be a trend for fewer measurements to be made than recommended, which means that the onset, peak and cessation of bubbling may be overlooked and misreported. This review summarises comprehensive Doppler data collected over 15 years across many dive profiles and then assesses the effectiveness of measurements made between 30 and 60 minutes (min) post-dive (commonly measured time points made in recent studies) in characterising the evolution and peak of venous gas emboli (VGE). VGE evolution in this dive series varied enormously both intra- and inter-individually and across dive profiles. Median, rather than mean values are best reported when describing data which have a non-linear relation to the underlying number of bubbles, as are median peak grades, rather than maximum, which may reflect only one individual's data. With regard to monitoring, it is apparent that the evolution of VGE cannot be described across multiple dive profiles using measurements made at only 30 to 60 min, or even 90 min post-dive. Earlier and more prolonged measurement is recommended, while the frequency of measurements should also be increased; in doing so, the accuracy and value of studies dependent on bubble evolution will be improved.

  • 227. Blogg, S. Lesley
    et al.
    Gennser, Mikael
    KTH, School of Technology and Health (STH), Basic Science and Biomedicine, Environmental Physiology.
    Møllerløkken, Andreas
    Brubakk, Alf O.
    Ultrasound detection of vascular decompression bubbles: the influence of new technology and considerations on bubble load2014In: Diving and Hyperbaric Medicine, ISSN 1833-3516, Vol. 44, no 1, p. 35-44Article, review/survey (Refereed)
    Abstract [en]

    Introduction: Diving often causes the formation of 'silent' bubbles upon decompression. If the bubble load is high, then the risk of decompression sickness (DCS) and the number of bubbles that could cross to the arterial circulation via a pulmonary shunt or patent foramen ovale increase. Bubbles can be monitored aurally, with Doppler ultrasound, or visually, with two-dimensional (2D) ultrasound imaging. Doppler grades and imaging grades can be compared with good agreement. Early 2D imaging units did not provide such comprehensive observations as Doppler, but advances in technology have allowed development of improved, portable, relatively inexpensive units. Most now employ harmonic technology; it was suggested that this could allow previously undetectable bubbles to be observed. Methods: This paper provides a review of current methods of bubble measurement and how new technology may be changing our perceptions of the potential relationship of these measurements to decompression illness. Secondly, 69 paired ultrasound images were made using conventional 2D ultrasound imaging and harmonic imaging. Images were graded on the Eftedal-Brubakk (EB) scale and the percentage agreement of the images calculated. The distribution of mismatched grades was analysed. Results: Fifty-four of the 69 paired images had matching grades. There was no significant difference in the distribution of high or low EB grades for the mismatched pairs. Conclusions: Given the good level of agreement between pairs observed, it seems unlikely that harmonic technology is responsible for any perceived increase in observed bubble loads, but it is probable that our increasing use of 2D ultrasound to assess dive profiles is changing our perception of 'normal' venous and arterial bubble loads. Methods to accurately investigate the load and size of bubbles developed will be helpful in the future in determining DCS risk.

  • 228. Blogg, S. Lesley
    et al.
    Mollerlokken, Andreas
    Gennser, Mikael
    KTH, School of Technology and Health (STH), Basic Science and Biomedicine, Environmental Physiology.
    Observed decompression sickness and venous bubbles following 18-msw dive profiles using RN Table 112017In: Undersea & Hyperbaric Medicine, ISSN 1066-2936, Vol. 44, no 3, p. 211-219Article in journal (Refereed)
    Abstract [en]

    The venous bubble load in the body after diving may be used to infer risk of decompression sickness (DCS). Retrospective analysis of post-dive bubbling and DCS was made on seven studies. Each of these investigated interventions, using an 18 meters of sea water (msw) air dive profile from Royal Navy Table 11 (Mod Air Table), equivalent to the Norwegian Air tables. A recent neurological DCS case suggested this table was not safe as thought. Two-hundred and twenty (220) man-dives were completed on this profile. Bubble measurements were made following 219 man-dives, using Doppler or 2D ultrasound measurements made on the Kisman-Masurel and Eftedal-Brubakk scales, respectively. The overall median grade was KM/EB 0.5 and the overall median maximum grade was KM/EB 2. Two cases of transient shoulder discomfort ("niggles") were observed (0.9% (95% CL 0.1% 3.3%)) and were treated with surface oxygen. One dive, for which no bubble measurements were made, resulted in a neurological DCS treated with hyperbaric oxygen. The DCS risk of this profile is below that predicted by models, and comparison of the cumulative incidence of DCS of these data to the large dataset compiled by DCIEM [1, 2], show that the incidence is lower than might be expected.

  • 229. Blogg, SL
    et al.
    Gennser, Mikael
    KTH, School of Technology and Health (STH), Basic Science and Biomedicine, Environmental Physiology.
    The use of ultrasound bubble detection to develop the Swedish Navy trimix dive tables2015Conference paper (Refereed)
  • 230. Blogg, SL
    et al.
    Møllerløkken, A
    Gennser, Mikael
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Response: car wrecks and caution: a lament on getting the facts straight in scientific reporting.2017In: Undersea Hyperb Med, Vol. 44, p. 492-494Article in journal (Other (popular science, discussion, etc.))
  • 231. Blomqvist, Göran
    et al.
    Norrström, Ann-Catrine
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Johansson Thunqvist, Eva-Lotta
    KTH, School of Technology and Health (STH), Centres, Centre for Health and Building, CHB.
    Miljöproblem vid drift och underhåll av vägar2001Report (Other academic)
  • 232. Blystad, I
    et al.
    Håkansson, I
    Tisell, A
    Ernerudh, J
    Smedby, Örjan
    KTH, School of Technology and Health (STH), Medical Engineering, Medical Image Processing and Visualization. Linköping University.
    Lundberg, P
    Larsson, E-M
    Quantitative MRI for Analysis of Active Multiple Sclerosis Lesions without Gadolinium-Based Contrast Agent2015In: American Journal of Neuroradiology, ISSN 0195-6108, E-ISSN 1936-959XArticle in journal (Refereed)
    Abstract [en]

    BACKGROUND AND PURPOSE: Contrast-enhancing MS lesions are important markers of active inflammation in the diagnostic work-up of MS and in disease monitoring with MR imaging. Because intravenous contrast agents involve an expense and a potential risk of adverse events, it would be desirable to identify active lesions without using a contrast agent. The purpose of this study was to evaluate whether pre-contrast injection tissue-relaxation rates and proton density of MS lesions, by using a new quantitative MR imaging sequence, can identify active lesions.

    MATERIALS AND METHODS: Forty-four patients with a clinical suspicion of MS were studied. MR imaging with a standard clinical MS protocol and a quantitative MR imaging sequence was performed at inclusion (baseline) and after 1 year. ROIs were placed in MS lesions, classified as nonenhancing or enhancing. Longitudinal and transverse relaxation rates, as well as proton density were obtained from the quantitative MR imaging sequence. Statistical analyses of ROI values were performed by using a mixed linear model, logistic regression, and receiver operating characteristic analysis.

    RESULTS: Enhancing lesions had a significantly (P < .001) higher mean longitudinal relaxation rate (1.22 ± 0.36 versus 0.89 ± 0.24), a higher mean transverse relaxation rate (9.8 ± 2.6 versus 7.4 ± 1.9), and a lower mean proton density (77 ± 11.2 versus 90 ± 8.4) than nonenhancing lesions. An area under the receiver operating characteristic curve value of 0.832 was obtained.

    CONCLUSIONS: Contrast-enhancing MS lesions often have proton density and relaxation times that differ from those in nonenhancing lesions, with lower proton density and shorter relaxation times in enhancing lesions compared with nonenhancing lesions.

  • 233. Blystad, Ida
    et al.
    Warntjes, J. B. Marcel
    Smedby, Örjan
    KTH, School of Technology and Health (STH), Medical Engineering, Medical Image Processing and Visualization. Linköping University, Sweden.
    Lundberg, Peter
    Larsson, Elna-Marie
    Tisell, Anders
    Quantitative MRI for analysis of peritumoral edema in malignant gliomas2017In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 12, no 5, article id e0177135Article in journal (Refereed)
    Abstract [en]

    Background and purpose Damage to the blood-brain barrier with subsequent contrast enhancement is a hallmark of glioblastoma. Non-enhancing tumor invasion into the peritumoral edema is, however, not usually visible on conventional magnetic resonance imaging. New quantitative techniques using relaxometry offer additional information about tissue properties. The aim of this study was to evaluate longitudinal relaxation R-1, transverse relaxation R-2, and proton density in the peritumoral edema in a group of patients with malignant glioma before surgery to assess whether relaxometry can detect changes not visible on conventional images. Methods In a prospective study, 24 patients with suspected malignant glioma were examined before surgery. A standard MRI protocol was used with the addition of a quantitative MR method (MAGIC), which measured R-1, R-2, and proton density. The diagnosis of malignant glioma was confirmed after biopsy/surgery. In 19 patients synthetic MR images were then created from the MAGIC scan, and ROIs were placed in the peritumoral edema to obtain the quantitative values. Dynamic susceptibility contrast perfusion was used to obtain cerebral blood volume (rCBV) data of the peritumoral edema. Voxel-based statistical analysis was performed using a mixed linear model. Results R-1, R-2, and rCBV decrease with increasing distance from the contrast-enhancing part of the tumor. There is a significant increase in R1 gradient after contrast agent injection (P<.0001). There is a heterogeneous pattern of relaxation values in the peritumoral edema adjacent to the contrast-enhancing part of the tumor. Conclusion Quantitative analysis with relaxometry of peritumoral edema in malignant gliomas detects tissue changes not visualized on conventional MR images. The finding of decreasing R-1 and R-2 means shorter relaxation times closer to the tumor, which could reflect tumor invasion into the peritumoral edema. However, these findings need to be validated in the future.

  • 234.
    Bodin, Ida
    KTH, School of Technology and Health (STH), Ergonomics.
    Using Cognitive Work Analysis to identify opportunities for enhancing human-heavy vehicle system performance2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the road transportation industry development is moving towards more advanced technology and the use of automation in the driving environment is increasing. Regarding the safety risks associated with an unconsidered use of a high degree of automation, it is expensive to develop automatic systems dealing with complex situations. As there is still much improvement to do in this area, this thesis aims to contribute to developing safe autonomic systems to assist truck drivers.

    The aim of the study was twofold, namely 1) to use Cognitive Work Analysis to identify opportunities for enhancing human-heavy vehicle system performance and 2) to contribute to improving the possibilities for identifying opportunities for enhancing system performance through the development of a method of prioritizing Activities using a Contextual Activity Template.

    To identify the opportunities for improvement, the first two phases of a Cognitive Work Analysis (CWA) – Work Domain Analysis (WDA) and Control Task Analysis (ConTA), were conducted.

    To complete the WDA, five hours of interviews were conducted with a senior technical adviser from Scania CV AB as well as a two hour interview with an experienced commercial driver. Additionally, an observation study was conducted during which three video cameras were used to capture sixteen hours of footage (per camera) from 35 hours (2500kms) of observation (one driver/day over a four day period). During the observation study, drivers were asked to talk out loud about the information needed, decisions made and to provide some rational for their behavior at that time with respect to their driving activities. A total of 40 minutes of talk out loud video data was collected per driver. Finally, around five hours of follow-up interviews were conduct-ed during which these drivers reviewed the videos collected during the observation study.

    The results from the WDA were presented in an Abstraction Hierarchy. The overall functional purpose of the system was defined as Goods Distribution via Road Transportation with the values and priorities being Effectivity and Efficiency, Safety, Comfort, Laws/regulations, Reputation, and Organizational Regulations. For the WDA in the current thesis, the AH was completed for the first three values listed above. In total the AH included 343 nodes (39 at the Purpose Related Functions level, 77 at the Object Related Processes level, and 211 at the Physical Objects level).

    The means by which the physical objects were used in different situations was described using a Contractual Activity Template. The object related processes defined in the AH were crosschecked with 42 situations identified during the observation study. Eight hours of further interviews were conducted with the previously-observed drivers to better understand the relationship between the object related processes and the situations. The object related process-situations matrix was then prioritized according to importance and frequency. On the basis of this prioritization, a set of potential improvement areas were identified, as for example communication and visibility during highway driving.

  • 235.
    Bohgard, Mats
    et al.
    Lunds Universitet.
    Karlsson, StigLuleå tekniska universitet.Lovén, EvaLinköpings universitet.Mikaelsson, Lars-ÅkeMittuniversitetet.Mårtensson, LenaKTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Industrial Work Science (closed 20130101).Osvalder, Anna-LisaChalmers tekniska högskola.Rose, Linda M.KTH, School of Technology and Health (STH), Ergonomics (Closed 20130701).Ulfvengren, PernillaKTH, School of Industrial Engineering and Management (ITM).
    Arbete och teknik på människans villkor2008Collection (editor) (Refereed)
  • 236.
    Bohgard, Mats
    et al.
    Lunds universitet.
    Karlsson, Stig
    Luleå tekniska universitet.
    Lovén, Eva
    Linköpings universitet.
    Mikaelsson, Lars-Åke
    Mittuniversitetet.
    Mårtensson, Lena
    KTH, School of Industrial Engineering and Management (ITM).
    Osvalder, Anna-Lisa
    Chalmers tekniska högskola.
    Rose, Linda M.
    KTH, School of Technology and Health (STH), Ergonomics (Closed 20130701).
    Ulfvengren, Pernilla
    KTH, School of Industrial Engineering and Management (ITM).
    Designing work and technology on human terms2009In: Work and technology on human terms / [ed] Bohgard, M., Karlsson, S., Lovén, E., Mikaelsson, L.-Å., Mårtensson, L., Osvalder, A.-L., Rose, L., & Ulfvengren, P, Stockholm: Prevent , 2009, 1:1, p. 9-18Chapter in book (Other (popular science, discussion, etc.))
  • 237.
    Bohgard, Mats
    et al.
    Lunds universitet.
    Karlsson, StigLuleå tekniska universitet.Lovén, EvaLinköpings universitet.Mikaelsson, Lars-ÅkeMittuniversitetet.Mårtensson, LenaKTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Industrial Work Science (closed 20130101).Osvalder, Anna-LisaChalmers tekniska högskola.Rose, Linda M.KTH, School of Technology and Health (STH), Ergonomics (Closed 20130701).Ulfvengren, PernillaKTH, School of Industrial Engineering and Management (ITM).
    Work and technology on human terms2009Collection (editor) (Refereed)
  • 238.
    Bohgard, Mats
    et al.
    Lunds universitet.
    Karlsson, Stig
    Luleå tekniska universitet.
    Lovén, Eva
    Linköpings universitet.
    Mikaelsson, Lars-Åke
    Mittuniversitetet.
    Osvalder, Anna-Lisa
    Chalmers tekniska högskola.
    Rose, Linda M.
    KTH, School of Technology and Health (STH), Ergonomics (Closed 20130701).
    Ulfvengren, Pernilla
    KTH, School of Industrial Engineering and Management (ITM).
    Att utforma arbete och teknik på människans villkor2008In: Arbete och teknik på människans villkor / [ed] Bohgard, M., Karlsson, S., Lovén, E., Mikaelsson, L.-Å., Mårtensson, L., Osvalder, A.-L., Rose, L., & Ulfvengren, P., Stockholm: Prevent , 2008, 1:1, p. 9-17Chapter in book (Other (popular science, discussion, etc.))
  • 239.
    Boije, Malin
    et al.
    KTH, School of Technology and Health (STH).
    Trovald, Adam
    KTH, School of Technology and Health (STH).
    Ljudfeedback som hjälpmedel för att reducera risken för stressfrakturer i tibia vid löpning2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 240. Boman, Inga-Lill
    et al.
    Lundberg, Stefan
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    Starkhammar, Sofia
    Nygard, Louise
    Exploring the usability of a videophone mock-up for persons with dementia and their significant others2014In: BMC Geriatrics, ISSN 1471-2318, E-ISSN 1471-2318, Vol. 14, p. 49-Article in journal (Refereed)
    Abstract [en]

    Background: Persons with dementia might have considerable difficulties in using an ordinary telephone. Being able to use the telephone can be very important in order to maintain their social network, getting stimulation and for reaching help when needed. Therefore, persons with dementia might need an easy-to-use videophone to prevent social isolation and to feel safe and independent. This study reports the evaluation of the usability of a touch-screen videophone mock-up for persons with dementia and their significant others. Methods: Four persons with dementia and their significant others tested the videophone mock-up at a living laboratory. In order to gain knowledge of the participants' with dementia ability to use their own computers and telephones, interviews and observations were conducted. Results: Overall, the participants had a very positive attitude towards the videophone. The participants with dementia perceived that it was useful, enjoyable and easy to use, although they initially had difficulties in understanding how to handle some functions, thus indicating that the design needs to be further developed to be more intuitive. Conclusions: The findings suggest that the videophone has the potential to enable telephone calls without assistance and add quality in communication.

  • 241.
    Boman, Inga-Lill
    et al.
    Karolinska Institutet.
    Rosenberg, Lena
    Karolinska Institutet.
    Lundberg, Stefan
    KTH, School of Technology and Health (STH), Centres, Centre for Health and Building, CHB.
    Nygård, Louise
    Karolinska Institutet.
    First steps in designing a videophone for people with dementia: Identification of users' potentials and the requirements of communication technology2012In: Disability and Rehabilitation: Assistive Technology, ISSN 1748-3107, E-ISSN 1748-3115, Vol. sept, no 5, p. 356-363Article in journal (Refereed)
    Abstract [en]

    Purpose: To identify, based on the literature, people with dementia´s potentials to manage an easy-to-use videophone, and to develop a videophone requirement specification for people with dementia.

    Method:The study is based on the Inclusive Design method, utilising the first two of four phases. Content analyses of literature reviews were used to identify users´potentials for managing a videophone and to gather recommendations regarding communication technology design for the target group. Existing videophones in Sweden were examined regarding potentia fit to users with dementia.Findings: This led to detailed identification of cognitive, physical and psychosocial challenges that people with dementia will probably have when using an ordinary telephone or videophone. A requirement specification for videophone design to fit users with dementia was formulated, with the seven principles of Universal Design as a framework.Conclusions: The requirement specification presented here is aimed at designing a videophone but might also facilitate design of other products for people with dementia, particularly in the field of communication technology. Based on this, further work will focus on developing a design concept and a prototype to be empirically tested by people with dementia and their significant others, i.e. the final two design process phases.

  • 242.
    Boongerd, Sanhawad
    et al.
    KTH, School of Technology and Health (STH), Data- och elektroteknik.
    Lindstein, Fredrik
    KTH, School of Technology and Health (STH), Data- och elektroteknik.
    Analys av datakommunikationssäkerhet för VoIP-protokoll2012Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Voice over IP (VoIP) is a relatively new technology that enables voice calls over data networks.With VoIP it is possible to lower expenses, and increase functionality and flexibility. FromSwedish Armed Forces point of view, the security issue is of great importance, why the focus inthis report is on the security aspect of the two most common open-source VoIP-protocols H.323and SIP, some of the most common attacks, and counter-measures for those attacks.Because of the level of complexity with a network running H.323 or SIP, and the fact that it hasyet to stand the same level of trial as of traditional telephony, a VoIP-system includes manyknown security-issues, and probably at present many unknown security flaws.

    The conclusion is that it takes great knowledge and insight about a VoIP-network based onH.323 or SIP to make the network satisfyingly safe as it is today, and is therefore perhaps not asuitable solution for the Swedish Armed Forces today for their more sensitive communications.

  • 243. Bora, K.
    et al.
    Chowdhury, Manish
    KTH, School of Technology and Health (STH).
    Mahanta, L. B.
    Kundu, M. K.
    Das, A. K.
    Pap smear image classification using convolutional neural network2016In: ACM International Conference Proceeding Series, Association for Computing Machinery , 2016Conference paper (Refereed)
    Abstract [en]

    This article presents the result of a comprehensive study on deep learning based Computer Aided Diagnostic techniques for classification of cervical dysplasia using Pap smear images. All the experiments are performed on a real indigenous image database containing 1611 images, generated at two diagnostic centres. Focus is given on constructing an effective feature vector which can perform multiple level of representation of the features hidden in a Pap smear image. For this purpose Deep Convolutional Neural Network is used, followed by feature selection using an unsupervised technique with Maximal Information Compression Index as similarity measure. Finally performance of two classifiers namely Least Square Support Vector Machine (LSSVM) and Softmax Regression are monitored and classifier selection is performed based on five measures along with five fold cross validation technique. Output classes reflects the established Bethesda system of classification for identifying pre-cancerous and cancerous lesion of cervix. The proposed system is also compared with two existing conventional systems and also tested on a publicly available database. Experimental results and comparison shows that proposed system performs efficiently in Pap smear classification.

  • 244. Bora, Kangkana
    et al.
    Chowdhury, Manish
    KTH, School of Technology and Health (STH).
    Mahanta, Lipi B.
    Kundu, Malay Kumar
    Das, Anup Kumar
    Automated classification of Pap smear images to detect cervical dysplasia2017In: Computer Methods and Programs in Biomedicine, ISSN 0169-2607, E-ISSN 1872-7565, Vol. 138, p. 31-47Article in journal (Refereed)
    Abstract [en]

    Background and objectives: The present study proposes an intelligent system for automatic categorization of Pap smear images to detect cervical dysplasia, which has been an open problem ongoing for last five decades. Methods: The classification technique is based on shape, texture and color features. It classifies the cervical dysplasia into two-level (normal and abnormal) and three-level (Negative for Intraepithelial Lesion or Malignancy, Low-grade Squamous Intraepithelial Lesion and High-grade Squamous Intraepithelial Lesion) classes reflecting the established Bethesda system of classification used for diagnosis of cancerous or precancerous lesion of cervix. The system is evaluated on two generated databases obtained from two diagnostic centers, one containing 1610 single cervical cells and the other 1320 complete smear level images. The main objective of this database generation is to categorize the images according to the Bethesda system of classification both of which require lots of training and expertise. The system is also trained and tested on the benchmark Herlev University database which is publicly available. In this contribution a new segmentation technique has also been proposed for extracting shape features. Ripplet Type I transform, Histogram first order statistics and Gray Level Co-occurrence Matrix have been used for color and texture features respectively. To improve classification results, ensemble method is used, which integrates the decision of three classifiers. Assessments are performed using 5 fold cross validation. Results: Extended experiments reveal that the proposed system can successfully classify Pap smear images performing significantly better when compared with other existing methods. Conclusion: This type of automated cancer classifier will be of particular help in early detection of cancer.

  • 245.
    Borell, Lena
    et al.
    Karolinska Institutet.
    Johansson, Karin
    Karolinska Institutet.
    Lundberg, Stefan
    KTH, School of Technology and Health (STH), Centres, Centre for Health and Building, CHB.
    Kognitiva köket - framtidens kök2010Report (Other academic)
    Abstract [sv]

    Äldre personer som har en demenssjukdom eller andra medicinska diagnoser som kan leda till kognitiva problem och som bor i egna hem är en växande grupp. Samtidigt så förväntas alla oavsett funktionsnedsättning kunna hantera matlagning och andra köksrelaterade aktiviteter på egen hand.

    Personer med kognitiva problem, och personer som arbetar med denna grupp definierar problem relaterade till matlagning och att hålla ordning i köket som några av de viktigaste att lösa (Wherton and Monk 2008). Att kunna utföra köksrelaterade aktiviteter betraktas som något som höjer livskvaliteten. Trots det växande behovet av att kunna skapa köksmiljöer och köksprodukter, både generellt och med individuella anpassningar, finns det i dag ingen samlad kunskap om hur sådana miljöer och produkter bäst kan utformas.

    I det här projektet ses köket som en plats där flera dimensioner av livet pågår. Förutom matlagning och förvaring av mat så är köket även en plats för socialt umgänge, och utgör vardagens nav. Kökets roll i hemmet är alltså central. Projektet utgår från att det är möjligt att skapa inkluderande köksmiljöer som tar hänsyn till personer med nedsatt kognition, men som samtidigt förenklar för alla.

    Modern design av kök handlar idag mycket om eleganta ytor och dolda, och därmed svårdefinierade, funktioner vilket skapar problem för personer med kognitiva funktionsnedsättningar. Dessa problem måste lyftas fram och diskuteras för att kunna utforma framtida inkluderande köksmiljöer. Syftet med projektet är att, i dialog med intressenter och experter inom området, sammanställa och generera kunskap om hur kök och köksprodukter kan designas för att underlätta för äldre människor med kognitiva nedsättningar att kunna använda sina kök utan problem.

  • 246.
    Borg, Malin
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Ghattas, Elias
    KTH, School of Technology and Health (STH). KTH, School of Engineering Sciences (SCI), Applied Physics.
    Syla, Ardian
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Graphical User Interface for Intermodulation Atomic Force Microscopyok.2011Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In atomic force microscopy (AFM) a cantilever, with a sharp tip attached

    to its free end, is scanned over a surface. Forces from the surface aect

    the tip causing cantilever deection, which is registered by a detector. This

    information is then used to create a topographical image of the surface on

    nanoscale. We were a part of a project that developed a new type of AFM,

    namely intermodulation atomic force microscopy (IMAFM). It is based on

    dynamic AFM, but instead of one drive frequency, two or more frequencies

    are used. This generates more information from the sample. Our part in this

    project was to improve the software already in use. This will facilitate future

    simulations and experiments; and also utilize the available information in a

    new way.

  • 247.
    Borg Tornberg, Anette
    et al.
    KTH, School of Technology and Health (STH), Ergonomics.
    Hurtig, Anna
    KTH, School of Technology and Health (STH), Ergonomics.
    Bärbara datorer, en möjlig källa för nickel- och koboltexponering av hud?: Direktvisande tester för nickel och kobolt på bärbara datorer och frisättningsförsök på en bärbar dator2012Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Background: Since1994, the EU NickelDirective is limiting the release of nickel from objects that are in prolongedcontact with skin. Despite this, nickel is still the most common cause of contactallergy in industrialized countries. This could implicate that other productswith short contact to the skin, which are not restricted by EU´s legislation inREACH (Registration, Evaluation, Authorisation and Restriction of Chemicalsubstances), could be a source of nickel or cobalt exposure. There is no limitfor cobalt release within REACH. To determine if there is cobalt or nickelpresent on the surface of a material and if metal can be released in contactwith the skin, there are quantitative and qualitative methods, such as the DMG(dimethylglyoxime)-test, the cobalt spot-test and a method for releasedetermination according to EN1811.Objectives: Laptops are not included in the REACH legislation. The purpose of thisstudy was to investigate whether nickel or cobalt can be found on computersurfaces and if nickel and cobalt can be released from surfaces that are incontact with skin, during work with laptops. Are there any variations betweendifferent models or different brands of laptops (two years old or less) andwhat levels of nickel and cobalt are released from different surfaces on a specificHP computer, that gave positive results for nickel and cobalt in the spot- tests? Methodand materials: In this study 30laptops (7 Hewlett Packard (HP), 18 Dell, 3 Sony Vaio, 1Fujitsu and 1 Macbook), weretested by using DMG-test and cobalt spot-test. To measure the release of nickeland cobalt on one specific laptop (HP2560p), the standard method EN1811 and amodified version of the method, were used. Results: Laptopsof different models and manufacturers were tested for nickel by using theDMG-test. The test turned out positive for all tested laptops from HP and 4 of18 of the laptops from Dell. For cobalt, onlyone laptop (HP) of the total 30 computers, gave a positive result. The resultsfrom the release test of a specific laptop, was lower than the limit thresholdvalue within REACH (0.5µg/cm2/week). The highest amounts of nickel,0.1μg/cm2/week, were measured for the computer components thatwere derived from the palm rest. All the cobalt levels, except one, were belowthe detection limit for the analysis. Conclusions: Our study indicatesthat laptops are a potential source for nickel deposition onto skin. In this study, computers from five differentmanufacturers have been tested, and it turned out that the tested models from HPand Dell released nickel. Cobalt was only released in very low concentrations,at a level near the LOD for the analysis.

  • 248.
    Borgström, Dennis
    et al.
    KTH, School of Technology and Health (STH).
    Nummisalo, Linda
    KTH, School of Technology and Health (STH).
    Utvärdering av smarta kläder för användning inom arbetslivet2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The aim of this project was to contribute to the development of wearable technology. Two smart shirts were compared against each other. One of the shirts (Hexoskin-shirt) was developed by a company called Hexoskin. The other shirt (X-shirt) was developed by a collaboration by KTH and University of Borås. The smart shirts were first validated against established measurement procedures that were acquired with an ECG and a spirometer developed by the company ADInstruments. The pulse and breathing rate from both shirts correlated well with the "gold standard". A test person in apparent good health performed six simulated working tasks from different work categories. This was done to test a concept that could be used to evaluate risks in working life. Also, software was developed to analyze and visualize the workload based on heart rate and respiration rate.

    The results showed that the ECG-signals from both shirts were robust against movement artifacts. On the other hand, the respiration signals were affected by movement artifacts. The quality of the signal depended on the wetness of the textile electrodes. Both smart shirts' electrodes needed to be wet before usage. Evaporation from the electrodes was limited for X-shirt due to a waterproof layer; therefore, X-shirt would be preferable for ergonomic evaluation that takes place during a long time with low physical activity.

    Hexoskin-shirt proved to be more robust than X-shirt, as X-shirt’s electrodes lost good skin-contact at times. In order to make X-shirt even more suitable for measuring ergonomic parameters its chest strap could be made tighter and shoulder straps could be made more elastic. This could give the electrodes better contact with the body.

  • 249.
    Borgström, Fredrik
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Acceleration of FreeRTOS withSierra RTOS accelerator: Implementation of a FreeRTOS software layer onSierra RTOS accelerator2016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Today, the effect of the most common ways to improve the performance of embedded systems and real-time operating systems is stagnating. Therefore it is interesting to examine new ways to push the performance boundaries of embedded systems and real-time operating systems even further. It has previously been demonstrated that the hardware-based real-time operating system, Sierra, has better performance than the software-based real-time operating system, FreeRTOS. These real-time operating systems have also been shown to be similar in many aspects, which mean that it is possible for Sierra to accelerate FreeRTOS. In this thesis an implementation of such acceleration has been carried out. Because existing real-time operating systems are constantly in development combined with that it was several years since an earlier comparison between the two real-time operating systems was per-formed, FreeRTOS and Sierra were compared in terms of functionality and architecture also in this thesis. This comparison showed that FreeRTOS and Sierra share the most fundamental functions of a real-time operating system, and thus can be accelerated by Sierra, but that FreeRTOS also has a number of exclusive functions to facilitate the use of that real-time operating system. The infor-mation obtained by this comparison was the very essence of how the acceleration would be imple-mented. After a number of performance tests it could be concluded that all of the implemented functions, with the exception of a few, had shorter execution time than the corresponding functions in the original version of FreeRTOS.

  • 250. Borosund, Elin
    et al.
    Cvancarova, Milada
    Moore, Shirley M.
    Ekstedt, Mirjam
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    Ruland, Cornelia M.
    Preliminary Results Of Two Web-Based Interventions On Symptom Distress, Anxiety And Depression Among Breast Cancer Patients2014In: Annals of Behavioral Medicine, ISSN 0883-6612, E-ISSN 1532-4796, Vol. 47, p. S188-S188Article in journal (Other academic)
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