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  • 1.
    Aare, Magnus
    et al.
    KTH, School of Technology and Health (STH), Neuronic Engineering (Closed 20130701).
    Kleiven, Svein
    KTH, School of Technology and Health (STH), Neuronic Engineering (Closed 20130701).
    Evaluation of head response to ballistic helmet impacts, using FEM2003Conference paper (Refereed)
  • 2. Aare, Magnus
    et al.
    Kleiven, Svein
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Evaluation of head response to ballistic helmet impacts using the finite element method2007In: International Journal of Impact Engineering, ISSN 0734-743X, E-ISSN 1879-3509, Vol. 34, no 3, 596-608 p.Article in journal (Refereed)
    Abstract [en]

    Injuries to the head caused by ballistic impacts are not well understood. Ballistic helmets provide good protection, but still, injuries to both the skull and brain occur. Today there is a lack of relevant test procedure to evaluate the efficiency of a ballistic helmet. The purpose of this project was (1) to study how different helmet shell stiffness affects the load levels in the human head during an impact, and (2) to study how different impact angles affects the load levels in the human head. A detailed finite element (FE) model of the human head, in combination with an FE model of a ballistic helmet (the US Personal Armour System Ground Troops' (PASGT) geometry) was used. The head model has previously been validated against several impact tests on cadavers. The helmet model was validated against data from shooting tests. Focus was aimed on getting a realistic response of the coupling between the helmet and the head and not on modeling the helmet in detail. The studied data from the FE simulations were stress in the cranial bone, strain in the brain tissue, pressure in the brain, change in rotational velocity and translational and rotational acceleration. A parametric study was performed to see the influence of a variation in helmet shell stiffness on the outputs from the model. The effect of different impact angles was also studied. Dynamic helmet shell deflections larger than the initial distance between the shell and the skull should be avoided in order to protect the head from the most injurious threat levels. It is more likely that a fracture of the skull bone occurs if the inside of the helmet shell strikes the skull. Oblique ballistic impacts may in some cases cause higher strains in the brain tissue than pure radial ones.

  • 3.
    Aare, Magnus
    et al.
    KTH, School of Technology and Health (STH), Neuronic Engineering (Closed 20130701).
    Kleiven, Svein
    KTH, School of Technology and Health (STH), Neuronic Engineering (Closed 20130701).
    Halldin, Peter
    KTH, School of Technology and Health (STH), Neuronic Engineering (Closed 20130701).
    Proposed global injury thresholds for oblique helmet impacts2003Conference paper (Refereed)
  • 4. Aare, Magnus
    et al.
    von Holst, Hans
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Injuries from motorcycle- and moped crashes in Sweden from 1987 to 1999.2003In: Injury control and safety promotion, ISSN 1566-0974, E-ISSN 1744-4985, Vol. 10, no 3, 131-8 p.Article in journal (Refereed)
    Abstract [en]

    The objective of this paper is to study injuries from motorcycle and moped crashes in Sweden from 1987 to 1999. Databases at the National Board for Health and Welfare and codes from both ICD9 and ICD10 systems were used, including patterns of age, gender, E-code and type of injury. Length of hospital stay, type of injuries and trends over time was evaluated. To get a more detailed picture of the age distribution, type of vehicle used and number of killed, data from the Swedish National Road Administration were also used. In Sweden, 27,122 individuals received in-patient care due to motorcycle and moped injuries between 1987 and 1999. The motorcycle and moped injury rate was reduced in the second half of the studied period and so were the total days of treatment per year. Males had eight times the incidence of injuries compared to females. Riders under the age of 26 and in particular those at an age of 15 had the highest incidence rate. Head injuries were the most frequent diagnosis, followed by fractures to the lower limbs. Concussion was the most frequent head injury. Focal and diffuse brain injuries combined showed the same frequency as concussion. It is concluded that more preventative strategies must be presented before the injury rate can be reduced.

  • 5. Aberg, A. C.
    et al.
    Thorstensson, A.
    Tarassova, O.
    Halvorsen, Kjartan
    KTH, School of Technology and Health (STH).
    Calculations of mechanisms for balance control during narrow and single-leg standing in fit older adults: A reliability study2011In: Gait & Posture, ISSN 0966-6362, E-ISSN 1879-2219, Vol. 34, no 3, 352-357 p.Article in journal (Refereed)
    Abstract [en]

    For older people balance control in standing is critical for performance of activities of daily living without falling. The aims were to investigate reliability of quantification of the usage of the two balance mechanisms M(1) 'moving the centre of pressure' and M(2) 'Segment acceleration' and also to compare calculation methods based on a combination of kinetic (K) and kinematic (Km) data, (K-Km), or Km data only concerning M(2). For this purpose nine physically fit persons aged 70-78 years were tested in narrow and single-leg standing. Data were collected by a 7-camera motion capture system and two force plates. Repeated measure ANOVA and Tukey's post hoc tests were used to detect differences between the standing tasks. Reliability was estimated by ICCs, standard error of measurement including its 95% Cl, and minimal detectable change, whereas Pearson's correlation coefficient was used to investigate agreement between the two calculation methods. The results indicated that for the tasks investigated, M(1) and M(2) can be measured with acceptable inter- and intrasession reliability, and that both Km and K-Km based calculations may be useful for M(2), although Km data may give slightly lower values. The proportional M(1) :M(2) usage was approximately 9:1, in both anterio-posterior (AP) and medio-lateral (ML) directions for narrow standing, and about 2:1 in the AP and of 1:2 in the ML direction in single-leg standing, respectively. In conclusion, the tested measurements and calculations appear to constitute a reliable way of quantifying one important aspect of balance capacity in fit older people.

  • 6. Aberg, B
    et al.
    Koul, B L
    Liska, J
    Brodin, L A
    KTH, School of Technology and Health (STH).
    Landou, C
    Delayed left ventricular free wall rupture complicating coronary artery bypass surgery. A case report.1985In: Scandinavian journal of thoracic and cardiovascular surgery, ISSN 0036-5580, Vol. 19, no 3, 273-7 p.Article in journal (Refereed)
    Abstract [en]

    Rupture of the left ventricular free wall is a not uncommon life-threatening complication of acute myocardial infarction and after prosthetic mitral valve replacement. To our knowledge, no case of left ventricular rupture after coronary artery bypass surgery has been reported. A case is now described in which coronary artery bypass grafting was complicated by delayed rupture, which was successfully repaired. Different etiologic factors are discussed, but the cause considered most likely was trauma from elevation of and traction on the heart in exposure of its posterior aspect.

  • 7.
    Abrahamsson, Anna-Carin
    KTH, School of Technology and Health (STH).
    Den fysiska arbetsmiljön i förskolan: utveckling, användning och granskning av en riskbedömningsmodell2016Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The occupational environment in preschool is becoming increasingly important. Occupational injury statistics show an increased incidence of illness among employees in education, health and care. Before action can be taken to improve the working environment, a careful assessment must be made and an action plan created. To include all possible components requires a comprehensive approach. Mapping of the physical work in Hudiksvall Municipality at all preschools provides a means by which to get an overall picture of risk areas within the preschool staff work environment.

    The aim of this work is to describe how the risk assessment model was developed and used with the ambition that it can be used in other municipalities. The model has been tested in Hudiksvall, on two occasions, in 2005 and 2010. The findings from the survey in 2010 are reported here and a comparison with 2005 is made.

    The risk assessment model is based on a survey with open questions for preschool staff combined with observation and assessment of ergonomics and safety engineer of 11 risk areas within the physical environment of the pre-school.

    The results of the survey give a clear picture of current health risks and can be used as a basis for the development of pre-school activities as well as improved maintenance of the municipal buildings. The results have also been communicated to the individual pre-schools to demonstrate their particular areas of risk.

    The combination of survey and professional assessment of several risk areas has been shown to enable a quick identification of possible causes of illness among pre-school staff. To report both positive and negative environmental factors has been an advantage. The clear method of reporting has facilitated decision-making on what if any actions to take. There is a continuing need to develop this and other instruments for the work environment survey of schools, health and social care.

  • 8.
    Abtahi, Farhad
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Aspects of Electrical Bioimpedance Spectrum Estimation2014Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Electrical bioimpedance spectroscopy (EBIS) has been used to assess the status or composition of various types of tissue, and examples of EBIS include body composition analysis (BCA) and tissue characterisation for skin cancer detection. EBIS is a non-invasive method that has the potential to provide a large amount of information for diagnosis or monitoring purposes, such as the monitoring of pulmonary oedema, i.e., fluid accumulation in the lungs. However, in many cases, systems based on EBIS have not become generally accepted in clinical practice. Possible reasons behind the low acceptance of EBIS could involve inaccurate models; artefacts, such as those from movements; measurement errors; and estimation errors. Previous thoracic EBIS measurements aimed at pulmonary oedema have shown some uncertainties in their results, making it difficult to produce trustworthy monitoring methods. The current research hypothesis was that these uncertainties mostly originate from estimation errors. In particular, time-varying behaviours of the thorax, e.g., respiratory and cardiac activity, can cause estimation errors, which make it tricky to detect the slowly varying behaviour of this system, i.e., pulmonary oedema.

    The aim of this thesis is to investigate potential sources of estimation error in transthoracic impedance spectroscopy (TIS) for pulmonary oedema detection and to propose methods to prevent or compensate for these errors.   This work is mainly focused on two aspects of impedance spectrum estimation: first, the problems associated with the delay between estimations of spectrum samples in the frequency-sweep technique and second, the influence of undersampling (a result of impedance estimation times) when estimating an EBIS spectrum. The delay between frequency sweeps can produce huge errors when analysing EBIS spectra, but its effect decreases with averaging or low-pass filtering, which is a common and simple method for monitoring the time-invariant behaviour of a system. The results show the importance of the undersampling effect as the main estimation error that can cause uncertainty in TIS measurements.  The best time for dealing with this error is during the design process, when the system can be designed to avoid this error or with the possibility to compensate for the error during analysis. A case study of monitoring pulmonary oedema is used to assess the effect of these two estimation errors. However, the results can be generalised to any case for identifying the slowly varying behaviour of physiological systems that also display higher frequency variations.  Finally, some suggestions for designing an EBIS measurement system and analysis methods to avoid or compensate for these estimation errors are discussed.

  • 9.
    Abtahi, Farhad
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Towards Heart Rate Variability Tools in P-Health: Pervasive, Preventive, Predictive and Personalized2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Heart rate variability (HRV) has received much attention lately. It has been shown that HRV can be used to monitor the autonomic nervous system and to detect autonomic dysfunction, especially vagal dysfunction. Reduced HRV is associated with several diseases and has also been suggested as a predictor of poor outcomes and sudden cardiac death. HRV is, however, not yet widely accepted as a clinical tool and is mostly used for research. Advances in neuroimmunity with an improved understanding of the link between the nervous and immune systems have opened a new potential arena for HRV applications. An example is when systemic inflammation and autoimmune disease are primarily caused by low vagal activity; it can be detected and prognosticated by reduced HRV. This thesis is the result of several technical development steps and exploratory research where HRV is applied as a prognostic diagnostic tool with preventive potential. The main objectives were 1) to develop an affordable tool for the effective analysis of HRV, 2) to study the correlation between HRV and pro-inflammatory markers and the potential degree of activity in the cholinergic anti-inflammatory pathway, and 3) to develop a biofeedback application intended for support of personal capability to increase the vagal activity as reflected in increased HRV. Written as a compilation thesis, the methodology and the results of each study are presented in each appended paper. In the thesis frame/summary chapter, a summary of each of the included papers is presented, grouped by topic and with their connections. The summary of the results shows that the developed tools may accurately register and properly analyse and potentially influence HRV through the designed biofeedback game. HRV can be used as a prognostic tool, not just in traditional healthcare with a focus on illness but also in wellness. By using these tools for the early detection of decreased HRV, prompt intervention may be possible, enabling the prevention of disease. Gamification and serious gaming is a potential platform to motivate people to follow a routine of exercise that might, through biofeedback, improve HRV and thereby health.

  • 10.
    Abtahi, Farhad
    et al.
    KTH, School of Technology and Health (STH). Karolinska Institute, Sweden.
    Anund, A.
    Fors, C.
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering. Karolinska Institute, Sweden.
    Lindecrantz, Kaj
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering. Karolinska Institute, Sweden.
    Association of drivers’ sleepiness with heart rate variability: A pilot study with drivers on real roads2017In: EMBEC & NBC 2017, Springer, 2017, Vol. 65, 149-152 p.Conference paper (Refereed)
    Abstract [en]

    Vehicle crashes lead to huge economic and social consequences, and one non-negligible cause of accident is driver sleepiness. Driver sleepiness analysis based on the monitoring of vehicle acceleration, steering and deviation from the road or physiological and behavioral monitoring of the driver, e.g., monitoring of yawning, head pose, eye blinks and eye closures, electroencephalogram, electrooculogram, electromyogram and electrocardiogram (ECG), have been used as a part of sleepiness alert systems. Heart rate variability (HRV) is a potential method for monitoring of driver sleepiness. Despite previous positive reports from the use of HRV for sleepiness detection, results are often inconsistent between studies. In this work, we have re-evaluated the feasibility of using HRV for detecting drivers’ sleepiness during real road driving. A database consists of ECG measurements from 10 drivers, driving during morning, afternoon and night sessions on real road were used. Drivers have reported their average sleepiness level by using the Karolinska sleepiness scale once every five minutes. Statistical analysis was performed to evaluate the potential of HRV indexes to distinguish between alert, first signs of sleepiness and severe sleepiness states. The results suggest that individual subjects show different reactions to sleepiness, which produces an individual change in HRV indicators. The results motivate future work for more personalized approaches in sleepiness detection.

  • 11.
    Abtahi, Farhad
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Berndtsson, Andreas
    Abtahi, Shirin
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Lindecrantz, Kaj
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Development and preliminary evaluation of an Android based heart rate variability biofeedback system2014In: Engineering in Medicine and Biology Society (EMBC), 2014 36th Annual International Conference of the IEEE, IEEE conference proceedings, 2014, 3382-3385 p.Conference paper (Refereed)
    Abstract [en]

    The reduced Heart Rate Variability (HRV) is believed to be associated with several diseases such as congestive heart failure, diabetes and chronic kidney diseases (CKD). In these cases, HRV biofeedback may be a potential intervention method to increase HRV which in turn is beneficial to these patients. In this work, a real-time Android biofeedback application based on a Bluetooth enabled ECG and thoracic electrical bioimpedance (respiration) measurement device has been developed. The system performance and usability have been evaluated in a brief study with eight healthy volunteers. The result demonstrates real-time performance of system and positive effects of biofeedback training session by increased HRV and reduced heart rate. Further development of the application and training protocol is ongoing to investigate duration of training session to find an optimum length and interval of biofeedback sessions to use in potential interventions.

  • 12.
    Abtahi, Farhad
    et al.
    KTH, School of Technology and Health (STH), Patient Safety (Closed 20130701).
    Gyllensten, Illapha Cuba
    KTH, School of Technology and Health (STH).
    Lindecrantz, Kaj
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701).
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701).
    Software tool for analysis of breathing-related errors in transthoracic electrical bioimpedance spectroscopy measurements2012In: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 407, no 1, 012028- p.Article in journal (Refereed)
    Abstract [en]

    During the last decades, Electrical Bioimpedance Spectroscopy (EBIS) has been applied in a range of different applications and mainly using the frequency sweep-technique. Traditionally the tissue under study is considered to be timeinvariant and dynamic changes of tissue activity are ignored and instead treated as a noise source. This assumption has not been adequately tested and could have a negative impact and limit the accuracy for impedance monitoring systems. In order to successfully use frequency-sweeping EBIS for monitoring time-variant systems, it is paramount to study the effect of frequency-sweep delay on Cole Model-based analysis. In this work, we present a software tool that can be used to simulate the influence of respiration activity in frequency-sweep EBIS measurements of the human thorax and analyse the effects of the different error sources. Preliminary results indicate that the deviation on the EBIS measurement might be significant at any frequency, and especially in the impedance plane. Therefore the impact on Cole-model analysis might be different depending on method applied for Cole parameter estimation.

  • 13.
    Abtahi, Farhad
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems. Karolinska Institutet, Sweden.
    Hilderman, Marie
    Bruchfeld, Annette
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems. University of Borås, Sweden.
    Janerot-Sjöberg, Birgitta
    KTH, School of Technology and Health (STH), Medical Engineering, Medical Imaging. Karolinska Institutet, Sweden.
    Lindecrantz, Kaj
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems. Karolinska Institutet, Sweden.
    Pro-inflammatory Blood Markers and Heart Rate Variability in Apnoea as a Reflection of Basal Vagal ToneManuscript (preprint) (Other academic)
    Abstract [en]

    Pro-inflammatory cytokines play a crucial role in inflammatory response, which istightly regulated by the nervous system to avoid the damage caused by inflammation. There isevidence for a cholinergic anti-inflammatory pathway that includes afferent and efferent vagalnerves that sense the inflammation and stimulate the anti-inflammatory response. Non-functionalanti-inflammatory response might lead to excessive and chronic inflammation e.g., rheumatoidarthritis (RA), inflammatory bowel disease (IBD), and poor outcome. Heart rate variability(HRV) has been proposed as a potential tool to monitor the level of anti-inflammatory activitythrough the monitoring of vagal activity. In this paper, the association of pro-inflammatorymarkers with HRV indices is evaluated. We used a database called “Heart Biomarker Evaluationin Apnea Treatment (HeartBEAT)” that consists of 6±2 hours of Electrocardiogram (ECG)recordings during nocturnal sleep from 318 patients at baseline and 301of them at 3 monthsfollow-up. HRV indices are calculated from ECG recordings of 5-360 minutes. The results showa statistically significant correlation between heart rate (HR) and pro-inflammatory cytokines,independent of duration of ECG analysis. HRV indices e.g., standard deviation of all RRintervals (SDNN) show an inverse relation to the pro-inflammatory cytokines. Longer ECGrecordings show a higher potential to reflect the level of anti-inflammatory response. In light oftheories for the cholinergic anti-inflammatory pathway, a combination of HR and HRV as areflection of basal vagal activity might be a potential prognostic tool for interventional guidance.

  • 14.
    Abtahi, Farhad
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Ji, Guangchao
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Lu, Ke
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Rodby, Kristian
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    A knitted garment using intarsia technique for Heart Rate Variability biofeedback: Evaluation of initial prototype2015In: Engineering in Medicine and Biology Society (EMBC), 2015 37th Annual International Conference of the IEEE, IEEE , 2015, Vol. 2015, 3121-3124 p.Conference paper (Refereed)
    Abstract [en]

    Heart rate variability (HRV) biofeedback is a method based on paced breathing at specific rate called resonance frequency by giving online feedbacks from user respiration and its effect on HRV. Since the HRV is also influence by different factors like stress and emotions, stress related to an unfamiliar measurement device, cables and skin electrodes may cover the underling effect of such kind of intervention. Wearable systems are usually considered as intuitive solutions which are more familiar to the end-user and can help to improve usability and hence reducing the stress. In this work, a prototype of a knitted garment using intarsia technique is developed and evaluated. Results show the satisfactory level of quality for Electrocardiogram and thoracic electrical bioimpedance i.e. for respiration monitoring as a part of HRV biofeedback system. Using intarsia technique and conductive yarn for making the connection instead of cables will reduce the complexity of fabrication in textile production and hence reduce the final costs in a final commercial product. Further development of garment and Android application is ongoing and usability and efficiency of final prototype will be evaluated in detail.

  • 15.
    Abtahi, Farhad
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Ji, Guangchao
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Lu, Ke
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Rödby, Kristian
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Björlin, Anders
    Kiwok AB.
    Östlund, Anders
    Kiwok AB.
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems. Högskolan i Borås, Akademin för vård, arbetsliv och välfärd.
    Lindecrantz, Kaj
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Textile-Electronic Integration in Wearable Measurement Garments for Pervasive Healthcare Monitoring2015Conference paper (Other academic)
  • 16.
    Abtahi, Farhad
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Lindecrantz, Kaj
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Aslamy, Benjamin
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Boujabir, Imaneh
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    An Affordable ECG and Respiration Monitoring System Based on Raspberry PI and ADAS1000: First Step towards Homecare Applications2015In: 16th Nordic-Baltic Conference on Biomedical Engineering: 16. NBC & 10. MTD 2014 joint conferences. October 14-16, 2014, Gothenburg, Sweden, Springer, 2015, 5-8 p.Conference paper (Refereed)
    Abstract [en]

    Homecare is a potential solution for problems associated with an aging population. This may involve several physiological measurements, and hence a flexible but affordable measurement device is needed. In this work, we have designed an ADAS1000-based four-lead electrocardiogram (ECG) and respiration monitoring system. It has been implemented using Raspberry PI as a platform for homecare applications. ADuM chips based on iCoupler technology have been used to achieve electrical isolation as required by IEC 60601 and IEC 60950 for patient safety. The result proved the potential of Raspberry PI for the design of a compact, affordable, and medically safe measurement device. Further work involves developing a more flexible software for collecting measurements from different devices (measuring, e.g., blood pressure, weight, impedance spectroscopy, blood glucose) through Bluetooth or user input and integrating them into a cloud-based homecare system.

  • 17.
    Abtahi, Farhad
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Lu, Ke
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Dizon, M
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Johansson, M
    KTH-School of Technology and Health.
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems. Högskolan i Borås.
    Lindecrantz, Kaj
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering. Högskolan i Borås, Akademin för vård, arbetsliv och välfärd.
    Evaluating Atrial Fibrillation Detection Algorithm based on Heart Rate Variability analysis2015In: Medicinteknikdagarna, Uppsala: Svensk förening för medicinsk teknik och fysik , 2015Conference paper (Refereed)
  • 18.
    Abtahi, Farhad
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Lu, Ke
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Dizon, M
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Johansson, M
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems. Högskolan i Borås, Akademin för vård, arbetsliv och välfärd.
    Lindecrantz, Kaj
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Evaluation of Atrial Fibrillation Detection by using Heart Rate Variability analysis2015Conference paper (Other academic)
  • 19.
    Abtahi, Farhad
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Lu, Ke
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Guangchao, Li
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Rödby, Kristian
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems. Högskolan i Borås.
    A Knitted Garment using Intarsia Technique for Heart Rate Variability Biofeedback: Evaluation of Initial Prototype.2015Conference paper (Other academic)
  • 20.
    Abtahi, Farhad
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Lindecrantz, Kaj
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Electrical bioimpedance spectroscopy in time-variant systems: Is undersampling always a problem?2014In: Journal of Electrical Bioimpedance, ISSN 1891-5469, Vol. 5, no 1, 28-33 p.Article in journal (Refereed)
    Abstract [en]

    During the last decades, Electrical Bioimpedance Spectroscopy (EBIS) has been applied mainly by using the frequency-sweep technique, across a range of many different applications. Traditionally, the tissue under study is considered to be time-invariant and dynamic changes of tissue activity are ignored by treating the changes as a noise source. A new trend in EBIS is simultaneous electrical stimulation with several frequencies, through the application of a multi-sine, rectangular or other waveform. This method can provide measurements fast enough to sample dynamic changes of different tissues, such as cardiac muscle. This high sampling rate comes at a price of reduction in SNR and the increase in complexity of devices. Although the frequency-sweep technique is often inadequate for monitoring the dynamic changes in a variant system, it can be used successfully in applications focused on the time-invariant or slowly-variant part of a system. However, in order to successfully use frequency-sweep EBIS for monitoring time-variant systems, it is paramount to consider the effects of aliasing and especially the folding of higher frequencies, on the desired frequency e.g. DC level. This paper discusses sub-Nyquist sampling of thoracic EBIS measurements and its application in the case of monitoring pulmonary oedema. It is concluded that by considering aliasing, and with proper implementation of smoothing filters, as well as by using random sampling, frequency-sweep EBIS can be used for assessing time-invariant or slowly-variant properties of time-variant biological systems, even in the presence of aliasing. In general, undersampling is not always a problem, but does always require proper consideration.

  • 21.
    Abtahi, Farhad
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Lindecrantz, Kaj
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Löfgren, Nils
    Elimination of ECG Artefacts in Foetal EEG Using Ensemble Average Subtraction and Wavelet Denoising Methods: A Simulation2014In: XIII Mediterranean Conference on Medical and Biological Engineering and Computing 2013, Springer, 2014, 551-554 p.Conference paper (Refereed)
    Abstract [en]

    Biological signals recorded from surface electrodes contain interference from other signals which are not desired and should be considered as noise. Heart activity is especially present in EEG and EMG recordings as a noise. In this work, two ECG elimination methods are implemented; ensemble average subtraction (EAS) and wavelet denoising methods. Comparison of these methods has been done by use of simulated signals achieved by adding ECG to neonates EEG. The result shows successful elimination of ECG artifacts by using both methods. In general EAS method which remove estimate of all ECG components from signal is more trustable but it is also harder for implementation due to sensitivity to noise. It is also concluded that EAS behaves like a high-pass filter while wavelet denoising method acts as low-pass filter and hence the choice of one method depends on application.

  • 22.
    Abtahi, Farhad
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Snäll, Jonatan
    KTH, School of Technology and Health (STH).
    Aslamy, Benjamin
    KTH, School of Technology and Health (STH).
    Abtahi, Shirin
    KTH, School of Technology and Health (STH).
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems. University of Boras, Sweden.
    Lindecrantz, Kaj
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems. Karolinska Institute, Sweden.
    Biosignal PI, an Affordable Open-Source ECG and Respiration Measurement System2014In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 15, no 1, 93-109 p.Article in journal (Refereed)
    Abstract [en]

    Bioimedical pilot projects e.g., telemedicine, homecare, animal and human trials usually involve several physiological measurements. Technical development of these projects is time consuming and in particular costly. A versatile but affordable biosignal measurement platform can help to reduce time and risk while keeping the focus on the important goal and making an efficient use of resources. In this work, an affordable and open source platform for development of physiological signals is proposed. As a first step an 8–12 leads electrocardiogram (ECG) and respiration monitoring system is developed. Chips based on iCoupler technology have been used to achieve electrical isolation as required by IEC 60601 for patient safety. The result shows the potential of this platform as a base for prototyping compact, affordable, and medically safe measurement systems. Further work involves both hardware and software development to develop modules. These modules may require development of front-ends for other biosignals or just collect data wirelessly from different devices e.g., blood pressure, weight, bioimpedance spectrum, blood glucose, e.g., through Bluetooth. All design and development documents, files and source codes will be available for non-commercial use through project website, BiosignalPI.org.

  • 23.
    Afroze, Tonima
    et al.
    KTH, School of Technology and Health (STH).
    Isaksson Palmqvist, Mia
    KTH, School of Technology and Health (STH).
    Patient Safety Regarding Medical Devices at ICUs in Bangladesh2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Accidents related to medical devices are a worldwide problem and result in many deaths each year. It affects patients, relatives, health care workers and society. Due to the complexity of intensive care units (ICUs), such accidents lead to particularly serious consequences. The aim of this thesis was to identify patient safety aspects at ICUs in public and private hospitals in Bangladesh, in order to provide a basis for improving the quality of performance of devices as well as personnel, care and cost effectiveness. The objectives were to

    a)      compare the conditions of medical devices at ICUs in private and public hospitals,

    b)      increase understanding of errors, risks and accidents related to medical devices,

    c)      study reporting systems and communication between staff at ICUs and

    d)      find ways to minimize hazards related to medical equipment to ensure effective and safe use of devices.

    Data was collected through interviews during field visits to six hospitals in Dhaka, Bangladesh. Interviews were held with the chiefs of the ICUs, physicians, nurses and technicians.

    It was noticed that the admission fees to the public hospitals were lower and had more limited resources. Differences between public and private hospitals could be seen in the aspects of finance, the existence of a Biomedical Engineering Department, maintenance and calibration of medical equipment, further education of staff, working environment and infection control. The reporting systems for adverse events and communication about patients’ conditions between coworkers were weak at all hospitals. The procurement process was lengthy at all hospitals. Access to disposable items was limited at several hospitals.

    The lower admission fee at the government hospitals results in the patients of these hospitals often having a lower income and status, thus less inclined to be critical of the received care.

    A number of suggestions have been proposed in order to improve the work in the ICU. These include

    a)      following up rules made by the authorities to ensure they are implemented at each hospital,

    b)      increasing documentation of malfunctioning devices and adverse events,

    c)      nurses and physicians taking part in the procurement process,

    d)      establishing a Biomedical Engineering Department at all hospitals,

    e)      organizing workshops for health care workers,

    f)       developing biomedical products adapted for multiple time use and with less need for calibration,

    g)      providing more education for health care workers in infection control, management of specific devices, solutions to common technical problems, patient safety and user safety, for example using Information and Communication Technology tools (audio and audiovisual material) and discussion platforms as well as

    h)      constructing an internet forum for consultation on the abovementioned subjects for technicians.

  • 24.
    Afroze, Tonima
    et al.
    KTH, School of Technology and Health (STH).
    Rosén Gardell, Moa
    KTH, School of Technology and Health (STH).
    Algorithm Construction for Efficient Scheduling of Advanced Health Care at Home2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Providing advanced health care at home rather than in a hospital creates a greater quality of life for patients and their families. It also lowers the risk of hospital-acquired infections and accelerates recovery. The overall cost of care per patient is decreased. Manual scheduling of patient visits by health care professionals (HCPs) has become a bottleneck for increased patient capacity at SABH, a ward providing advanced pediatric health care at home (“Sjukhusansluten Avancerad Barnsjukvård i Hemmet” in Swedish), since many parameters need to be taken into account during scheduling. This thesis aims to increase the efficiency of SABH’s daily scheduling of personnel and resources by designing an automated scheduler that constructs a daily schedule and incorporates changes in it when needed in order to remove scheduling as a limitation for increased patient capacity. Requirements on a feasible schedule are identified in cooperation with SABH and literature is investigated about similar areas where the scheduling process has been automated. The scheduling is formulated as a computerized problem and investigated from the perspective of theoretical computer science. We show that the scheduling problem is NP-hard and can therefore not be expected to be solved optimally. The algorithm for scheduling the visits minimizes violations of time windows and travel times, and maximizes person continuity and workload balancing. The algorithm constructs an initial solution that fulfills time constraints using a greedy approach and then uses local search, simulated annealing, and tabu search to iteratively improve the solution. We present an exact rescheduling algorithm that incorporates additional visits after the original schedule has been set. The scheduling algorithm was implemented and tested on real data from SABH. Although we found the algorithm to be efficient, automatic transfer of data from the patient journal system is an imperative for the scheduler to be adopted.

  • 25.
    Agerskov, Niels
    et al.
    KTH, School of Technology and Health (STH).
    Carrizo, Gabriel
    KTH, School of Technology and Health (STH).
    Application for Deriving 2D Images from 3D CT Image Data for Research Purposes2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Karolinska University Hospital, Huddinge, Sweden, has long desired to plan hip prostheses with Computed Tomography (CT) scans instead of plain radiographs to save time and patient discomfort. This has not been possible previously as their current software is limited to prosthesis planning on traditional 2D X-ray images. The purpose of this project was therefore to create an application (software) that allows medical professionals to derive a 2D image from CT images that can be used for prosthesis planning.

    In order to create the application NumPy and The Visualization Toolkit (VTK) Python code libraries were utilised and tied together with a graphical user interface library called PyQt4. The application includes a graphical interface and methods for optimizing the images for prosthesis planning.

    The application was finished and serves its purpose but the quality of the images needs to be evaluated with a larger sample group. 

  • 26.
    Ahlberg, Johan
    KTH, School of Technology and Health (STH).
    Real life analysis of myoelectric pattern recognition using continuous monitoring2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The use of non-invasive signal acquisition methods is today the standard for testing pattern recognition algorithms in prosthetic control. Such research had shown consecutively high performance on both prerecorded and real time data, yet when tested in real life they deteriorate.

    To investigate why, the author who is a congenital amputee, wore a prosthetic system utilizing pattern recognition control on a daily basis for a five-day period. The system generated one new classification every 50 ms and movement execution was made continuously; for classifying open/close; and by winning a majority vote; for classifying side grip, fine grip and pointer. System data was continuously collected and errors were registered through both a manual and an automatic log system.

    Calculations on extracted data show that grip classifications had an individual accuracy of 47%- 70% while open/close got 95%/98%, but if classified according to a majority vote, grips increased their accuracy to above 90% while open/close dropped to 80%. The conclusion was that majority vote might help complex classifications, like fine grips, while simpler proportional movements is exacerbated by majority voting. Major error sources were identified as signal similarities, electrode displacements and socket design.

    After the daily monitoring ended the systems functionality was tested using the "Assessment of Capacity for Myoelectric Control". The ACMC results showed that the system has similar functionality to commercial threshold control and thus is a possible viable option for both acquired and congenital amputees.

  • 27.
    Ahlberg, Johan
    et al.
    KTH, School of Technology and Health (STH).
    Wang, Jie Yu
    KTH, School of Technology and Health (STH).
    Utveckling av en teoretisk elektrokemisk apparatur för vattentransport i hjärnvävnad2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Every year in Sweden there is about 24,000 head injuries due to external trauma and 30,000 strokes. A significant number may develop secondary damage because of the increased water content around the damaged brain tissue. The proposed method is to induce water flow from damaged to healthy tissue based on the theory of electroosmosis. The theory behind the electroosmosis is that a flow is induced when a voltage is applied across a medium. The theory of electroosmosis is applied in industry and called electro-osmotic dewatering (EOD) which is used as a drying technique for the dewatering of bio-materials, clays, tofu sheets and electroosmosis is also applied in clinical treatment of tumors. Several experiments were performed on brain phantoms consisting of agarose gel to examine whether the method can be used to divert water. The first experiment was done prove that a flow can be induced when a voltage is applied over the phantom. The second experiment was to investigate the relationship between the flow rate, voltage and current. The result showed linear correlation between flow rate and voltage, flow rate and current, and between the voltage and current. The literature sources and experimental results were referred to a relationship which is developed to determine the flow induced by electrical field. The work was completed with recommendations in electrode material, design and placement. The recommendations are to use plate electrodes at a current density under 25 mA/m2. Electrode placement is predetermined by Finite Element (FE) simulations of different types of injuries.

  • 28. Ahlstrom, L.
    et al.
    Dellve, Lotta
    KTH, School of Technology and Health (STH), Health Systems Engineering, Ergonomics. University of Borås, Sweden.
    Hagberg, M.
    Ahlberg, K.
    Women with Neck Pain on Long-Term Sick Leave — Approaches Used in the Return to Work Process: A Qualitative Study2016In: Journal of occupational rehabilitation, ISSN 1053-0487, E-ISSN 1573-3688, 1-14 p.Article in journal (Refereed)
    Abstract [en]

    Purpose There are difficulties in the process of return to work (RTW) from long-term sick leave, both in general and regarding sick leave because of neck pain in particular. Neck pain is difficult to assess, problematic to rehabilitate, and hard to cure; and it is not always easy to decide whether the pain is work-related. The outcome of RTW could be dependent upon individuals’ approaches, defensive or offensive behaviors, and choices related to their self-efficacy. The aim of this study was to identify approaches used in the RTW process among women with neck pain on long-term sick leave from human service organizations. Methods This is a qualitative descriptive study based on grounded theory. A Swedish cohort of 207 women with a history of long-term sick leave with neck pain from human service organizations answered open-ended written questions at 0, 6, and 12 months, and 6 years; and 16 women were interviewed. Results Individuals expressed their coping approaches in terms of fluctuating in work status over time: either as a strategy or as a consequence. Periods of sick leave were interwoven with periods of work. The women were either controlling the interaction or struggling in the interaction with stakeholders. Conclusions Return to work outcomes may be improved if the fluctuating work status over time is taken into account in the design of rehabilitation efforts for women with a history of long-term sick leave and with chronical musculoskeletal conditions.

  • 29.
    Ahlstrom, L
    et al.
    Sahlgrenska Akademin.
    Hagberg, M
    Sahlgrenska Akademin.
    Dellve, Lotta
    KTH, School of Technology and Health (STH), Ergonomics.
    Workplace Rehabilitation and Supportive Conditions at Work: A Prospective Study2013In: Journal of occupational rehabilitation, ISSN 1053-0487, E-ISSN 1573-3688, Vol. 23, no 2, 248-260 p.Article in journal (Refereed)
    Abstract [en]

    Purpose To investigate the impact of rehabilitation measures on work ability and return to work (RTW), specifically the association between workplace rehabilitation/supportive conditions at work and work ability and RTW over time, among women on long-term sick leave. Methods Questionnaire data were collected (baseline, 6 and 12 months) from a cohort of women (n = 324). Linear mixed models were used for longitudinal analysis of the repeated measurements of work ability index (WAI), work ability score and working degree. These analyses were performed with different models; the explanatory variables for each model were workplace rehabilitation, supportive conditions at work and time. Results The individuals provided with workplace rehabilitation and supportive conditions (e.g. influence at work, possibilities for development, degree of freedom at work, meaning of work, quality of leadership, social support, sense of community and work satisfaction) had significantly increased WAI and work ability score over time. These individuals scored higher work ability compared to those individuals having workplace rehabilitation without supportive conditions, or neither. Additionally, among the individuals provided with workplace rehabilitation and supportive conditions, working degree increased significantly more over time compared to those individuals with no workplace rehabilitation and no supportive conditions. Conclusion The results highlight the importance of integrating workplace rehabilitation with supportive conditions at work in order to increase work ability and improve the RTW process for women on long-term sick leave.

  • 30.
    Ahlstrom, Linda
    et al.
    Högskolan Borås.
    Larsson Fallman, Sara
    Högskolan Borås.
    Dellve, Lotta
    KTH, School of Technology and Health (STH), Health Systems Engineering, Ergonomics. Public Health and Community Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
    Return to work from long-term sick leave: a five-year prospective study of the importance of adjustment latitudes at work and home2014Conference paper (Other academic)
    Abstract [en]

    Background

    Adjustment latitude among employees, i.e. adjusting work to individual’s health capacity, has been associated with successful return to work (RTW) in cross-sectional studies. The aim is to investigate the long-term importance of adjustment latitude at the workplace and at home, as well as attitudes (own and colleagues) for increased work ability (WA), working degree (WD) and health-related quality of life (HRQoL) among female human service workers (HSW) on long-term sick leave in Sweden.

    Methods

    A cohort of female HSW (n=324) on long-term sick leave (>60 day) received a questionnaire at four times (0, 6, 12, 60 months). Prevalence ratios (PR) were used to examine possible relationships between explanatory factors and outcomes. Linear mixed models were used for longitudinal analysis of the repeated measurements of WA Score (0-10), WD (0-100%) and HRQoL (0-100). Analyses were performed with different models; the explanatory variables for each model were adjustment latitude, attitudes towards breaks at work, shared or single household and amount of household work.

    Result

    Having more adjustment latitude at work was associated with both increased WA and RTW compared to having few adjustment latitude opportunities. Adjustments related to working-pace were strongly associated with increased WD (PR 3.29(95%CI=1.71-6.26)), as were adjustments to working-place. Having opportunities to take short breaks at work, and a general acceptance at work to take short breaks was associated with increased WA. At home, a higher responsibility for household work (PR 1.98(95%CI=1.33-2.95)) was related to increased WA and RTW. Individuals with possibilities for adjustment latitude, especially pace and place, at work, and an acceptance to take breaks at work, increased in WA score significantly more over time and had higher WA score compared with individuals not having such opportunities at work. These prospective results were similar for the outcome WD and HRQoL.

    Conclusions

    The results highlight the importance of possibilities for adjustment latitude at work and at home, as well as accepting attitudes to take short breaks to increase WA and RTW among female human service workers previously on long-term sick leave.

  • 31.
    Ahmadi, Ajda
    KTH, School of Technology and Health (STH).
    Design of an Improved Rapid Infuser for Safe and Reliable Fluid Resuscitation during Surgical Care2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Rapid infusers are used for rapid fluid administration as a part of medical treatment during surgical procedures. The rapid infusers on the market today have proved to present various functional, usability and safety issues for the customers and the problems have not been adequately addressed. This has motivated SLL Innovation to develop a new improved rapid infusion system. The primary reason for considering the development of a rapid infuser device was to meet customer demands and improve safety during the acute situations when the system is to be used. The Quality Function Deployment method was used to describe the design problem systematically and facilitate the development of an improved design. To investigate the users’ issues with existing rapid infusion devices, qualitative semi-structured interviews were conducted individually with hospital staff that had experience with the rapid infuser. Customer requirements were subsequently identified to form a basis for the development process.

    The results of the study indicated an evident demand for a new product. A three-dimensional (3D) computer aided design (CAD) solution was presented with enhanced properties and features that met the specifications identified. All the customer requirements were addressed in the final result. Safety was the highest rated engineering specification, thus a lot of time and effort was dedicated to solutions that could affect the safety of the system positively.

    Although the final design is expected to be more efficient and safer than the competition, further research and work is needed before this can be ensured.

  • 32.
    Ahmadi, Ajda
    et al.
    KTH, School of Technology and Health (STH).
    Dizon, Lucas
    KTH, School of Technology and Health (STH).
    Kärlstelhetsdetektion genom mätning av tryck och deformation: En experimentell ultraljudsbaserad studie2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 33.
    Ahmady, Tobias
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Klein Rosmar, Sander
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Translation of keywords between English and Swedish2014Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In this project, we have investigated how to perform rule-based machine translation of sets of keywords between two languages. The goal was to translate an input set, which contains one or more keywords in a source language, to a corresponding set of keywords, with the same number of elements, in the target language. However, some words in the source language may have several senses and may be translated to several, or no, words in the target language. If ambiguous translations occur, the best translation of the keyword should be chosen with respect to the context. In traditional machine translation, a word's context is determined by a phrase or sentences where the word occurs. In this project, the set of keywords represents the context.

    By investigating traditional approaches to machine translation (MT), we designed and described models for the specific purpose of keyword- translation. We have proposed a solution, based on direct translation for translating keywords between English and Swedish. In the proposed solu- tion, we also introduced a simple graph-based model for solving ambigu- ous translations. 

  • 34. Ahmed, Mona
    et al.
    Cerroni, Barbara
    Razuvaev, Anton
    Härmark, Johan
    KTH, School of Technology and Health (STH).
    Paradossi, Gaio
    Caidahl, Kenneth
    Gustafsson, Bjorn
    Cellular Uptake of Plain and SPION-Modified Microbubbles for Potential Use in Molecular Imaging2017In: Cellular and Molecular Bioengineering, ISSN 1865-5025, E-ISSN 1865-5033, Vol. 10, no 6, 537-548 p.Article in journal (Refereed)
    Abstract [en]

    Both diagnostic ultrasound (US) and magnetic resonance imaging (MRI) accuracy can be improved by using contrast enhancement. For US gas-filled microbubbles (MBs) or silica nanoparticles (SiNPs), and for MRI superparamagnetic or paramagnetic agents, contribute to this. However, interactions of MBs with the vascular wall and cells are not fully known for all contrast media. We studied the in vitro interactions between three types of non-targeted air-filled MBs with a polyvinyl-alcohol shell and murine macrophages or endothelial cells. The three MB types were plain MBs and two types that were labelled (internally and externally) with superparamagnetic iron oxide nanoparticles (SPIONs) for US/MRI bimodality. Cells were incubated with MBs and imaged by microscopy to evaluate uptake and adhesion. Interactions were quantified and the MB internalization was confirmed by fluorescence quenching of non-internalized MBs. Macrophages internalized each MB type within different time frames: plain MBs 6 h, externally labelled MBs 25 min and internally labelled MBs 2 h. An average of 0.14 externally labelled MBs per cell were internalized after 30 min and 1.34 after 2 h; which was 113% more MBs than the number of internalized internally labelled MBs. The macrophages engulfed these three differently modified new MBs at various rate, whereas endothelial cells did not engulf MBs. Polyvinyl-alcohol MBs are not taken up by endothelial cells. The MB uptake by macrophages is promoted by SPION labelling, in particular external such, which may be important for macrophage targeting.

  • 35.
    Ahmed, Olfet
    et al.
    KTH, School of Technology and Health (STH), Data- och elektroteknik.
    Saman, Nawar
    KTH, School of Technology and Health (STH), Data- och elektroteknik.
    Utvärdering av nätverkssäkerheten på J Bil AB2013Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The aim of this project is to evaluate the network security at J Bil AB. The focus will be on both social and technical issues. For the employees to be able to con-nect to remote servers and external services and perform their daily work tasks, secure connections is needed. J Bil Ab has no IT manager who actively maintains and monitors the network; rather they consult a computer company when changes and implementations are required. The projects’ goal is to identify gaps, come up with suggestions for improvement and to some extent implement so-lutions. To do this, an observation of the employees hav been made, an inter-view have been held, and several attacks on the network have been performed. Based on the data collected, it was concluded that the company has shortcom-ings in IT security. Above all, the social security appeared to have major gaps in it and that is mainly because the lack of knowledge among the employees and they have never been informed of how to manage their passwords, computers and IT issues in general. Suggestions for improvement have been given and some implementations have been performed to eliminate the deficiencies.

  • 36.
    Ahmed, Tanvir Saif
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Markovic, Bratislav
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Distribuerade datalagringssystem för tjänsteleverantörer: Undersökning av olika användningsfall för distribuerade datalagringssystem2016Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In this thesis, a study of three different uses cases has been made within the field of data storage, which are as following: Cold Storage, High Performance Storage and Virtual Machine Storage. The purpose of the survey is to give an overview of commercial distributed file systems and a deeper study of open source codes distributed file systems in order to find the most optimal solution for these use cases. Within the study, previous works concerning performance, data protection and costs were an-alyzed and compared in means to find different functionalities (snapshotting, multi-tenancy, data duplication and data replication) which distinguish modern distributed file systems. Both commercial and open distributed file systems were examined. A cost estimation for commercial and open distrib-uted file systems were made in means to find out the profitability for these two types of distributed file systems.After comparing and analyzing previous works, it was clear that the open source distributed file sys-tem Ceph was proper as a solution in accordance to the objectives that were set for High Performance Storage and Virtual Machine Storage. The cost estimation showed that it was more profitable to im-plement an open distributed file system. This study can be used as guidance to choose between different distributed file systems.

  • 37. Ahmed, Zara
    et al.
    Benque, David
    Berezin, Sergey
    Dahl, Anna Caroline E.
    KTH, School of Technology and Health (STH), Centres, Centre for Technology in Medicine and Health, CTMH.
    Fisher, Jasmin
    Hall, Benjamin A.
    Ishtiaq, Samin
    Nanavati, Jay
    Piterman, Nir
    Riechert, Maik
    Skoblov, Nikita
    Bringing LTL Model Checking to Biologists2017In: VMCAI 2017: Verification, Model Checking, and Abstract Interpretation / [ed] Bouajjani, A Monniaux, D, Springer, 2017, Vol. 10145, 1-13 p.Conference paper (Refereed)
    Abstract [en]

    The BioModelAnalyzer (BMA) is a web based tool for the development of discrete models of biological systems. Through a graphical user interface, it allows rapid development of complex models of gene and protein interaction networks and stability analysis without requiring users to be proficient computer programmers. Whilst stability is a useful specification for testing many systems, testing temporal specifications in BMA presently requires the user to perform simulations. Here we describe the LTL module, which includes a graphical and natural language interfaces to testing LTL queries. The graphical interface allows for graphical construction of the queries and presents results visually in keeping with the current style of BMA. The Natural language interface complements the graphical interface by allowing a gentler introduction to formal logic and exposing educational resources.

  • 38. Aili, K.
    et al.
    Nyman, Teresia
    KTH, School of Technology and Health (STH).
    Hillert, L.
    Svartengren, M.
    Sleep disturbances predict future sickness absence among individuals with lower back or neck-shoulder pain: A 5-year prospective study2015In: Scandinavian Journal of Public Health, ISSN 1403-4948, E-ISSN 1651-1905, Vol. 43, no 3, 315-323 p.Article in journal (Refereed)
    Abstract [en]

    Background: Musculoskeletal pain is one of the most common causes of sickness absence. Sleep disturbances are often co-occurring with pain, but the relationship between sleep and pain is complex. Little is known about the importance of self-reported sleep, when predicting sickness absence among persons with musculoskeletal pain. This study aims to study the association between self-reported sleep quality and sickness absence 5 years later, among individuals stratified by presence of lower back pain (LBP) and neck and shoulder pain (NSP). Methods: The cohort (n = 2286) in this 5-year prospective study (using data from the MUSIC-Norrtälje study) was stratified by self-reported pain into three groups: no LBP or NSP, solely LBP or NSP, and oncurrent LBP and NSP. Odds ratios (ORs) for the effect of self-reported sleep disturbances at baseline on sickness absence (> 14 consecutive days), 5 years later, were calculated. Results: Within all three pain strata, individuals reporting the most sleep problems showed a significantly higher OR for all-cause sickness absence, 5 years later. The group with the most pronounced sleep problems within the concurrent LBP and NSP stratum had a significantly higher OR (OR 2.00; CI 1.09-3.67) also for long-term sickness absence (> 90days) 5 years later, compared to the group with the best sleep. Conclusions: Sleep disturbances predict sickness absence among individuals regardless of co-existing features of LBP and/or NSP. The clinical evaluation of patients should take possible sleep disturbances into account in the planning of treatments.

  • 39.
    Aili, Katarina
    KTH, School of Technology and Health (STH), Ergonomics.
    Med uppstyckat arbete: En studie som mäter stress bland ackords- och linjestyckare2010Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Denna jämförande studie på magisternivå gjordes bland styckare på ett företag i Sverige. Studien gjordes i syfte att utreda hur styckare påverkas av de två vanligast förekommande arbetsuppläggen - arbete vid enkelbord och arbete vid linje. Åtta styckare deltog i studien. Ena veckan arbetade deltagarna vid enkelbord, med ackordslön, andra veckan arbetade de vid linje med maskinstyrt tempo, med lön som sätts utifrån takten på bandet. Stress mättes subjektivt med stress-energi-formuläret. Hjärtfrekvens mättes och jämfördes mellan de olika arbetsuppläggen. Observationer och intervjuer av samtliga deltagare utfördes.

    Skillnaden i arbetsuppläggen består i att styckarna vid enkelbord styckar en större del av grisen, att de väljer tempo själva samt att de arbetar ackordstyrt. Vid linje arbetar styckarna på löpande band under maskinstyrd arbetstakt, de har kortare arbetscykel och mer styrt arbete. Lönen vid linje sätts utifrån takten på bandet.

    En signifikant högre hjärtfrekvens uppmättes vid arbete, samt under pauser, då styckarna arbetade vid enkelbord jämfört med vid linje. Resultatet av svaren på stress-energi-formuläret visade något högre skattad stress vid linje och något högre skattad energi vid enkelbord. Skillnaden var inte signifikant. Beträffande intervjuerna uppgav fyra av åtta att de kände sig mer stressade vid linjearbetet, en av åtta att han kände sig mer stressad vid enkelbord. Fyra av åtta upplevde att de hade mer besvär i nacke/skuldra/rygg efter arbete vid linje, en upplevde mer besvär i nacke/skuldra/rygg efter arbete på enkelbord.

    Endast en av deltagarna uppmätte högre hjärtfrekvens vid arbete och paus vid linje än vid enkelbord. Samma deltagare upplevde arbetet vid linje som mer stressande, samt hade mer besvär av smärta efter arbete vid linje.

    Arbetsbelastningen mätt som hjärtfrekvens verkar således vara högre vid enkelbord. Däremot upplevde fler styckare mer stress och mer besvär i nacke/skuldra/rygg efter arbete vid linje. Det finns det anledning att tro att andra faktorer än den rena mekaniska belastningen styckarna utsätts för i sitt arbete kan vara en bidragande faktor vid besvärsförekomst.

  • 40.
    Akay, Altug
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    A Novel Method to Intelligently Mine Social Media to Assess Consumer Sentiment of Pharmaceutical Drugs2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis focuses on the development of novel data mining techniques that convert user interactions in social media networks into readable data that would benefit users, companies, and governments. The readable data can either warn of dangerous side effects of pharmaceutical drugs or improve intervention strategies. A weighted model enabled us to represent user activity in the network, that allowed us to reflect user sentiment of a pharmaceutical drug and/or service. The result is an accurate representation of user sentiment. This approach, when modified for specific diseases, drugs, and services, can enable rapid user feedback that can be converted into rapid responses from consumers to industry and government to withdraw possibly dangerous drugs and services from the market or improve said drugs and services.

    Our approach monitors social media networks in real-time, enabling government and industry to rapidly respond to consumer sentiment of pharmaceutical drugs and services.

  • 41.
    Akay, Altug
    et al.
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    Dragomir, A.
    Department of Biomedical Engineering, University of Houston, Houston, TX, US.
    Erlandsson, Björn-Erik
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    A novel data-mining approach leveraging social media to monitor and respond to outcomes of diabetes drugs and treatment2013In: 2013 IEEE Point-of-Care Healthcare Technologies (PHT), New York: IEEE , 2013, 264-266 p.Conference paper (Refereed)
    Abstract [en]

    A novel data-mining method was developed to gauge the experiences of medical devices and drugs by patients with diabetes mellitus. Self-organizing maps were used to analyze forum posts numerically to better understand user opinion of medical devices and drugs. The end-result is a word list compilation that correlates certain positive and negative word cluster groups with medical drugs and devices. The implication of this novel data-mining method could open new avenues of research into rapid data collection, feedback, and analysis that would enable improved outcomes and solutions for public health.

  • 42.
    Akay, Altug
    et al.
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    Dragomir, A
    Erlandsson, Björn-Erik
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    A Novel Data-Mining Approach Leveraging Social Media to Monitor Consumer Opinion of Sitagliptin2015In: IEEE journal of biomedical and health informatics, ISSN 2168-2194, E-ISSN 2168-2208, Vol. 19, no 1, 389-396 p.Article in journal (Refereed)
    Abstract [en]

    A novel data mining method was developed to gauge the experience of the drug Sitagliptin (trade name Januvia) by patients with diabetes mellitus type 2. To this goal, we devised a two-step analysis framework. Initial exploratory analysis using self-organizing maps was performed to determine structures based on user opinions among the forum posts. The results were a compilation of user's clusters and their correlated (positive or negative) opinion of the drug. Subsequent modeling using network analysis methods was used to determine influential users among the forum members. These findings can open new avenues of research into rapid data collection, feedback, and analysis that can enable improved outcomes and solutions for public health and important feedback for the manufacturer.

  • 43.
    Akay, Altug
    et al.
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    Dragomir, A.
    Erlandsson, Björn-Erik
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    A novel data-mining platform leveraging social media to monitor outcomes of Januvia2013In: Engineering in Medicine and Biology Society (EMBC), 2013 35th Annual International Conference of the IEEE, IEEE conference proceedings, 2013, 7484-7487 p.Conference paper (Refereed)
    Abstract [en]

    A novel data-mining method was developed to gauge the experiences of the diabetes mellitus drug Januvia. Self-organizing maps were used to analyze forum posts numerically to infer user opinion of drug Januvia. Graph theory was used to discover influential users. The result is a word list compilation correlating positive and negative word cluster groups and a web of influential users on Januvia. The implications could open new research avenues into rapid data collection, feedback, and analysis that would enable improved solutions for public health.

  • 44.
    Akay, Altug
    et al.
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    Dragomir, A
    Erlandsson, Björn-Erik
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    Network-Based Modeling and Intelligent Data Mining of Social Media for Improving Care2015In: IEEE journal of biomedical and health informatics, ISSN 2168-2194, E-ISSN 2168-2208, Vol. 19, no 1, 210-218 p.Article in journal (Refereed)
    Abstract [en]

    Intelligently extracting knowledge from social media has recently attracted great interest from the Biomedical and Health Informatics community to simultaneously improve healthcare outcomes and reduce costs using consumer-generated opinion. We propose a two-step analysis framework that focuses on positive and negative sentiment, as well as the side effects of treatment, in users' forum posts, and identifies user communities (modules) and influential users for the purpose of ascertaining user opinion of cancer treatment. We used a self-organizing map to analyze word frequency data derived from users' forum posts. We then introduced a novel network-based approach for modeling users' forum interactions and employed a network partitioning method based on optimizing a stability quality measure. This allowed us to determine consumer opinion and identify influential users within the retrieved modules using information derived from both word-frequency data and network-based properties. Our approach can expand research into intelligently mining social media data for consumer opinion of various treatments to provide rapid, up-to-date information for the pharmaceutical industry, hospitals, and medical staff, on the effectiveness (or ineffectiveness) of future treatments.

  • 45.
    Akay, Altug
    et al.
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    Dragomir, Andrei
    Erlandsson, Björn-Erik
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    A Novel-Data Mining Platform to Monitor the Outcomes of Erlontinib (Tarceva) using Social Media2014In: XIII Mediterranean Conference on Medical and Biological Engineering and Computing 2013, Springer, 2014, 1394-1397 p.Conference paper (Refereed)
    Abstract [en]

    A novel data-mining method was developed to gauge the experiences of the oncology drug Tarceva. Self-organizing maps were used to analyze forum posts numerically to infer user opinion of drug Tarceva. The result is a word list compilation correlating positive and negative word cluster groups and a web of influential users on Tarceva. The implica-tions could open new research avenues into rapid data collec-tion, feedback, and analysis that would enable improved solu-tions for public health.

  • 46.
    Akay, Altug
    et al.
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    Dragomir, Andrei
    Erlandsson, Björn-Erik
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    Assessing Antidepressants Using Intelligent Data Monitoring and Mining of Online Fora2016In: IEEE journal of biomedical and health informatics, ISSN 2168-2194, E-ISSN 2168-2208, Vol. 20, no 4, 977-986 p.Article in journal (Refereed)
    Abstract [en]

    Depression is a global health concern. Social networks allow the affected population to share their experiences. These experiences, when mined, extracted, and analyzed, can be converted into either warnings to recall drugs (dangerous side effects), or service improvement (interventions, treatment options) based on observations derived from user behavior in depression-related social networks. Our aim was to develop a weighted network model to represent user activity on social health networks. This enabled us to accurately represent user interactions by relying on the data's semantic content. Our three-step method uses the weighted network model to represent user's activity, and network clustering and module analysis to characterize user interactions and extract further knowledge from user's posts. The network's topological properties reflect user activity such as posts' general topic as well as timing, while weighted edges reflect the posts semantic content and similarities among posts. The result, a synthesis from word data frequency, statistical analysis of module content, and the modeled health network's properties, has allowed us to gain insight into consumer sentiment of antidepressants. This approach will allow all parties to participate in improving future health solutions of patients suffering from depression.

  • 47.
    Akay, Altug
    et al.
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    Dragomir, Andrei
    University of Houston, Biomedical Engineering.
    Erlandsson, Björn-Erik
    KTH, School of Technology and Health (STH), Health Systems Engineering.
    Mining Social Media Big Data for Health2015In: IEEE PulseArticle, review/survey (Refereed)
    Abstract [en]

    Advances in information technology (IT) and big data are affecting nearly every facet of the public and private sectors. Social media platforms are one example of such advances: its nature allows users to connect, collaborate, and debate on any topic with comparative ease. The result is a hefty volume of user-generated content that, if properly mined and analyzed, could help the public and private health care sectors improve the quality of their products and services while reducing costs. The users of these platforms are the key to these improvements, as their valuable feedback will help improve health solutions.

  • 48.
    Alaei, Zohreh
    KTH, School of Technology and Health (STH).
    Molecular Dynamics Simulations of Axonal Membrane in Traumatic Brain Injury2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The following project presents in silico investigation of axonal damage in Diffuse Axonal Injury (DAI). When axons face a shear force, orientation of the lipids in the axonal membrane gets disrupted. Depending on the value of the force, a tensile strain causes the axons to get partially or fully deformed and in some cases a pore forms in the membrane. Using Molecular Dynamic (MD) simulation and a coarse grain model, a series of bilayers with various bilayer structure (single bilayer, parallel bilayer and cylindrical bilayer) and similar composition to biological axonal membrane were simulated. This was initially done to investigate the strain rate dependency of the bilayers, and their viscoelastic ability on returning to their original shape from their deformed forms. To achieve this, various deformation velocities were applied to the bilayers reaching 20% strain and relaxing the bilayer after. Additionally, the bilayers were deformed further until they reached a pore. It was found that the bilayers can almost recover from their deformed forms to their original length when they were deformed at 20% strain level. In conjunction, no correlation between the deformation velocity and lipid deformation was observed. Further, it was found that bilayers with different lipid percentage to axonal bilayer has different strain values for water penetration and for pore formation. The strain value for cylindrical bilayer was found very high compared to the strain values found in vitro. The strain for pore formation of parallel and single bilayer was found to be around 80% to 90% and for water penetration was found to be 70% for single bilayer and 50% for parallel bilayer. A slight difference in strain for pore formation between single and parallel bilayer was found which showed the bilayer structure can play a role in simulation results. The effect of the length in the simulations results was also observed where shorter bilayers showed lower strain for pore formation compared to longer bilayers. 

  • 49.
    Alameddine, Raged
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Dashtbozorg, Sajad
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Utredning av för- och nackdelar med TN-S respektive TN-C system2016Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In this report analysis the advantages and disadvantages of the TN-C (four conductor system) and TN-S (five conductor system) system. There are different opinion about which system is most appropriate to use in the distribution network and the building main lines. With the help of literature studies and contacts with various power companies and electric companies different opinion have been discussed . TN-C is the most appropriate option in the distribution network and TN-S should be used in the building main lines. This for achieving high and stable electrical environment. This thesis will facilitate the choice of technology and hopefully increase the knowledge about the subject.

  • 50.
    Al-Battat, Ahmed
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Anwer, Noora
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Utvärdering utifrån ett mjukvaruutveckling perspektiv av ramverk för SharePoint2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The functionality was tested by two different tests, which showed that the product is suitable for usage in the intranet within a company or an organization, there are great benefits from using intranet as a tool for sharing of information. A good intranet contributes to a better flow of information and effective cooperation. SharePoint is a platform for intranet with interactive features, it makes the job easier for staff and even the company. The framework Omnia is a solution designed for Microsoft SharePoint 2013.This essay evaluates how Omnia acts as a framework and what the product is suitable for. Omnia framework evaluates carefully and is an independent assessment carried during this essay. The evaluation is based on scientific studies which are based on the qualitative and quantitative research methodology. The evaluator's main areas are based on system performance, scalability, architecture and functionality. A test prototype develops during the process in the form of an employee vacation request application by the development framework Omnia.The framework Omnia is considered to be suitable for the development of interactive web-based applications for SharePoint. The architecture for the system meets the requirements for scalable systems because it is based on the tier architecture. The system also has good performance but it needs to be improved if the number of users exceeds one thousand. The functionality of this product is quite suitable for the system's usage.

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