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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.
    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)
  • 3. Abrahamsson, S.
    et al.
    Blom, Hans
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Agostinho, A.
    Jans, Daniel
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Jost, A.
    Müller, M.
    Nilsson, Linnea
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Bernhem, K.
    Lambert, T. J.
    Heintzmann, R.
    Brismar, Hjalmar
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Multifocus structured illumination microscopy for fast volumetric super-resolution imaging2017In: Biomedical Optics Express, ISSN 2156-7085, E-ISSN 2156-7085, Vol. 8, no 9, p. 4135-4140, article id #294866Article in journal (Refereed)
    Abstract [en]

    We here report for the first time the synergistic implementation of structured illumination microscopy (SIM) and multifocus microscopy (MFM). This imaging modality is designed to alleviate the problem of insufficient volumetric acquisition speed in superresolution biological imaging. SIM is a wide-field super-resolution technique that allows imaging with visible light beyond the classical diffraction limit. Employing multifocus diffractive optics we obtain simultaneous wide-field 3D imaging capability in the SIM acquisition sequence, improving volumetric acquisition speed by an order of magnitude. Imaging performance is demonstrated on biological specimens.

  • 4.
    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.

  • 5.
    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.

  • 6. Abtahi, Farhad
    et al.
    Forsman, Mikael
    Diaz-Olivazrez, Jose A.
    KTH, School of Technology and Health (STH).
    Yang, Liyun
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Ergonomics.
    Lu, Ke
    KTH, School of Technology and Health (STH).
    Eklund, Jörgen
    KTH, School of Technology and Health (STH).
    Lindecrantz, Kaj
    KTH, School of Technology and Health (STH).
    Seoane, Fernando
    Teriö, Heikki
    Mediavilla Martinez, Cesar
    Aso, Santiago
    Tiemann, Christian
    Big Data & Wearable Sensors Ensuring Safety and Health @Work2017In: GLOBAL HEALTH 2017, The Sixth International Conference on Global Health Challenges, 2017Conference paper (Refereed)
    Abstract [en]

    —Work-related injuries and disorders constitute a major burden and cost for employers, society in general and workers in particular. We@Work is a project that aims to develop an integrated solution for promoting and supporting a safe and healthy working life by combining wearable technologies, Big Data analytics, ergonomics, and information and communication technologies. The We@Work solution aims to support the worker and employer to ensure a healthy working life through pervasive monitoring for early warnings, prompt detection of capacity-loss and accurate risk assessments at workplace as well as self-management of a healthy working life. A multiservice platform will allow unobtrusive data collection at workplaces. Big Data analytics will provide real-time information useful to prevent work injuries and support healthy working life

  • 7.
    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.

  • 8.
    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, p. 3121-3124Conference 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.

  • 9.
    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)
  • 10.
    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, p. 5-8Conference 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.

  • 11.
    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)
  • 12.
    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)
  • 13.
    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)
  • 14.
    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, p. 28-33Article 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.

  • 15.
    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, p. 551-554Conference 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.

  • 16.
    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, p. 93-109Article 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.

  • 17.
    Afkham, Heydar Maboudi
    et al.
    KTH, School of Biotechnology (BIO), Gene Technology.
    Ek, Carl Henrik
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Carlsson, Stefan
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Gradual improvement of image descriptor quality2014In: ICPRAM 2014 - Proceedings of the 3rd International Conference on Pattern Recognition Applications and Methods, 2014, p. 233-238Conference paper (Refereed)
    Abstract [en]

    In this paper, we propose a framework for gradually improving the quality of an already existing image descriptor. The descriptor used in this paper (Afkham et al., 2013) uses the response of a series of discriminative components for summarizing each image. As we will show, this descriptor has an ideal form in which all categories become linearly separable. While, reaching this form is not feasible, we will argue how by replacing a small fraction of these components, it is possible to obtain a descriptor which is, on average, closer to this ideal form. To do so, we initially identify which components do not contribute to the quality of the descriptor and replace them with more robust components. Here, a joint feature selection method is used to find improved components. As our experiments show, this change directly reflects in the capability of the resulting descriptor in discriminating between different categories.

  • 18.
    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.

  • 19.
    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.

  • 20.
    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. 

  • 21.
    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.

  • 22.
    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.

  • 23.
    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.

  • 24.
    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
  • 25. Ajalloueian, Fatemeh
    et al.
    Zeiai, Said
    Rojas, Ramiro
    Department of Chemistry, Division of Polymer Chemistry, Uppsala University, Sweden.
    Fossum, Magdalena
    Hilborn, Jöns
    One-Stage Tissue Engineering of Bladder Wall Patches for an Easy-To-Use Approach at the Surgical Table2013In: Tissue Engineering. Part C, Methods, ISSN 1937-3384, E-ISSN 1937-3392, Vol. 19, no 9, p. 688-696Article in journal (Refereed)
    Abstract [en]

    We present a method for producing a cell-scaffold hybrid construct at the bedside. The construct is composed of plastic-compressed collagen together with a poly(e-caprolactone) (PCL)-knitted mesh that yields an integrated, natural-synthetic scaffold. This construct was evaluated by seeding of minced bladder mucosa, followed by proliferation in vitro. High mechanical strength in combination with a biological environment suitable for tissue growth was achieved through the creation of a hybrid construct that showed an increased tensile strength (17.9 +/- 2.6 MPa) when compared to plastic-compressed collagen (0.6 +/- 0.12 MPa). Intimate contact between the collagen and the PCL fabric was required to ensure integrity without delamination of the construct. This contact was achieved by surface alkaline hydrolysis of the PCL, followed by adsorption of poly(vinyl) alcohol. The improvement in hydrophilicity of the PCL-knitted mesh was confirmed through water contact angle measurements, and penetration of the collagen into the mesh was evaluated by scanning electron microscopy (SEM). Particles of minced bladder mucosa tissue were seeded onto this scaffold, and the proliferation was followed for 6 weeks in vitro. Results obtained from phase contrast microscopy, SEM, and histological staining indicated that cells migrated from the minced tissue particles and reorganized on the scaffold. Cells were viable and proliferative, with morphological features characteristic of urothelial cells. Proliferation reached the point at which a multilayer with a resemblance to stratified urothelium was achieved. This successful method could potentially be used for in vivo applications in reconstructive urology as an engineered autologous tissue transplant without the requirement for in vitro culture before transplantation.

  • 26.
    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.

  • 27.
    Alander, Jarmo
    et al.
    Department of Electrical Engineering and Automation, University of Vaasa.
    Autere, Antti
    Department of Electrical Engineering and Automation, University of Vaasa.
    Kanniainen, Olli
    Department of Electrical Engineering and Automation, University of Vaasa.
    Koljonen, Janne
    Department of Electrical Engineering and Automation, University of Vaasa.
    Nordling, Torbjörn E M
    Department of Electrical Engineering and Automation, University of Vaasa.
    Välisuo, Petri
    Department of Electrical Engineering and Automation, University of Vaasa.
    Near infrared wavelength relevance detection of ultraviolet radiation-induced erythema2008In: Journal of Near Infrared Spectroscopy, ISSN 0967-0335, E-ISSN 1751-6552, Vol. 16, no 3, p. 233-241Article in journal (Refereed)
    Abstract [en]

    The acute effects of sun-bathing on the near-infrared absorption spectra of human skin were studied by exposing the shoulders of a male test subject to bright Finnish high summer mid-day sun. The spectra were measured before, immediately after and for several days after exposure. Four different spectral. processing and classification methods were applied to the data set to identify differences caused by exposure to the sun. The spectrophotometer and measuring procedure were found to cause some systematic errors, calling for further development, even though they could, to a large extent, be compensated for computationally. Spectral regions indicating ultraviolet radiation-induced erythema were Located and the degree of erythema could be predicted correctly but the signal is weak. This paper discusses promising wavelength selection methods to study the dermal effects of exposure to the sun, as well as difficulties and remedies of near infrared spectroscopic measurements of the skin.

  • 28.
    Alsaeede, Mustafa
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems.
    Test and Evaluation of a Novel Passive Tool Used For Blood Dilution in Hematology Analyzers2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Executive Summary

    The Complete Blood Count (CBC) is considered one of the most commonly performed screening tests in medical diagnostics. The CBC is performed using a hematological analyzer, which counts the numbers and types of different cells within the blood. However, due to the high concentration of cells in the blood samples to be counted, the dilution process is considered an essential factor for obtaining accurate counting results. Below is an investigation for an invention of a unique method and device for blood sample dilution in hematology analyzers. As mentioned, before starting an analysis a hematology cell counter device must dilute a precise defined volume of a whole blood sample with a diluent reagent (in this study 20ml of a blood sample is diluted with 4,5ml of diluent reagent). This dilution process must be accurate and repeatable with a high precision to produce the target dilution ratio (here 1:200). Exclusive to almost all hematology analyzers today, shear values (SV) are used to obtain highly precise volumes. These SV components are however very costly and add a higher complexity to the systems. This thesis was therefore aimed as an experimental evaluation for a novel passive dilution tool called shearing block (SB), which could possibly then replace the SV and be used in the coming Haematology Analyzer Devices manufactured by Boule Medical AB. The SB has the advantages of being low cost, having a simple mechanism, being much more flexible for integration with any microfluidic system and also eliminates the need for complex control systems or equipment, thereby lowering the need for calibration and maintenance. If a SB could replace the SV with an equally precise accuracy on the 20ml blood volume it would be highly beneficial.

     

    The set hypothesis was that the dilution process via the SB, will only be affected by blood viscosity. Through changing the blood’s viscosity, via changing the hematocrit concentration (HCT) and blood sample temperature, this study aimed to conclude if this gave a significant effect on the blood sample dilution via the SB. This was achieved through two performed experiments both including the same control group (CG) along with a test group (TG). All tests were performed using the same blood sample, the same reference measuring device (Medonic M32) and experimental setup. The experimental setup included the control group, CG, (N=30) consisting of 20µl blood samples aspirated through an electronic pipette in room temperature condition being mixed with 4,5ml of diluent reagent that had been automatically dispensed by the Medonic M32 instrument. The 20µl blood together with the 4,5ml diluent resulted in the targeted 1:200 dilution ratio. The test group, TG, (where N=30 for each respective group) was diluted through the SB through a fully automated process for the targeted 1:200 dilution. All diluted blood samples were then analyzed on the Medonic M32 for all hematology parameters and the hemoglobin (HGB) parameter was used as an indicator to quantify the blood volume in the TG runs as compared to the CG reference runs. Two test groups (TG) were analyzed: the first investigating the effect of the HCT and the second of the sample temperature on the blood volume (before dilution) in the SB. The HCT concentration levels were tested at 15%, 27%, 33% and 58% with samples and test run and kept at a constant 25°C. The second test group investigated the effect of 15°C, 25°C, 35°C and 39°C on a blood sample with a constant HCT of 33%.

    The main aim of this experimental study was to validate the SB simulation. However, the experiments results, showed that the diluted blood volume via SB was strongly influenced by changes in hematocrit concentration and that the unwanted additional blood volume, was increasing directly proportionally with hematocrit concentration.  On the other hand, there seemed to be no apparent change in the blood volume on the SB diluted samples for the various temperature differences between 15-35°C. To conclude, the experiments results were not consistent with predictions of SB simulation model and there are two reasons that could explain that. Firstly, in the simulation the blood was approximated with a homogeneous fluid with a given viscosity. The second reason is the mismatch between the dilution process via the SB and the simulation (the simulation started with an idealized initial status, whereas the SB channel was prefilled by blood). This means that the simulation excluded any effect that may occur as a convection effect during blood flow inside the channel and whilst encountering diluent reagent. These two reasons explain why the results of the simulation was not consistent with that of the experiments, regarding the unwanted blood volume. Therefore, a new simulation is required. Recommendations for future actions: undoubtedly there are several optimizations that may increase the accuracy of the proposed SB design such as; removing the diluent's reservoir for eliminating the effect of bubbles, changing the geometrical angles or use a smaller diameter for the inlets and outlets of the microchannels to reduce the convection and diffusion effect, (which in turn would reduce the unwanted blood volume). Therefore, determining the best SB's microchannel structure to perform the dilution process with minimum unwanted blood volume remains a near future next step follow-up project.

  • 29.
    Alvarez, Victor S
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Kleiven, Svein
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Importance of Windscreen Modelling Approach for Head Injury Prediction2016In: 2016 IRCOBI Conference Proceedings - International Research Council on the Biomechanics of Injury, 2016Conference paper (Refereed)
    Abstract [en]

    The objective of this study is to evaluate the capability of two modelling approaches in capturing  both accelerations and deformations from head impacts, and to evaluate the effect of modelling approach on  brain injury prediction. The first approach is a so‐called smeared technique, in which the properties of the two  glass  sheets and  the intermediate  polyvinyl  butyral  (PVB) are  combined and  divided into  two  coinciding  shell layers, of which one can fracture. The second approach consists of three shell layers, representing the glass and  PVB,  separated by  the  distance of  their  thickness, using a non‐local  failure criterion  to initiate  fracture in  the  glass.  The  two  modelling  approaches  are  compared  to  impact  experiments  of  flat  circular  windscreens,  measuring  deformations  and  accelerations  as  well  as  accelerations  from  impacts  against  full  vehicle  windscreens.  They  are  also  used  to  study  head‐to‐windscreen  impacts  using  a  detailed  Finite  Element  (FE)  model,  varying  velocity,  impact  direction  and  impact  point.  Only  the  non‐local  failure  model  is  able  to  adequately  capture  both  the accelerations and  deformations  of an  impactor. The FE  head model  simulations  also reveal that the choice of modelling approach has a large effect on the both localisation of the strain in the  brain and the characteristics of the strain‐time curve, with a difference in peak strain between 8% and 40%.  

  • 30. Ambrosi, D.
    et al.
    Ateshian, G. A.
    Arruda, E. M.
    Cowin, S. C.
    Dumais, J.
    Goriely, A.
    Holzapfel, Gerhard A.
    KTH, School of Engineering Sciences (SCI), Mechanics, Biomechanics.
    Humphrey, J. D.
    Kemkemer, R.
    Kuhl, E.
    Olberding, J. E.
    Taber, L. A.
    Garikipati, K.
    Perspectives on biological growth and remodeling2011In: Journal of the mechanics and physics of solids, ISSN 0022-5096, E-ISSN 1873-4782, Vol. 59, no 4, p. 863-883Article, review/survey (Refereed)
    Abstract [en]

    The continuum mechanical treatment of biological growth and remodeling has attracted considerable attention over the past fifteen years. Many aspects of these problems are now well-understood, yet there remain areas in need of significant development from the standpoint of experiments, theory, and computation. In this perspective paper we review the state of the field and highlight open questions, challenges, and avenues for further development.

  • 31.
    Ammendrup, Katrin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems.
    Framework for Wireless Acquisition of Surface EMG and Real-Time Control2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Muscle driven devices are controlled or powered with muscle activation. These devices open up the possibility of offering patients with limited muscle function to automatically control assistive devices - for instance exoskeletons - with input from their own muscles. This solution would help a number of patient groups suffering from common conditions, such as spinal cord injuries, stroke and cerebral palsy.

    To use muscle activation as input it is necessary to have a way to communicate with the mus- cles. Electromyography (EMG) is a technology used to gain information about muscle function and activation. It is performed by measuring and analyzing electrical signals conducted by the muscles during activation. Activation and activation level can be seen from analyzed EMG signal. EMG signals are frequently measured and analyzed afterwards, however, to use it as a controlling an assistive devices, real time analysis is necessary. In this thesis real time acquisi- tion and analysis of EMG was performed. The measured signal was used as an input to control a simple MATLAB computer game.

    The EMG of a muscle of the forearm, Brachioradialis, was measured with Myon Aktos sys- tem. The measured signal was written to a server as soon as the measurements were acquired. MATLAB was used to connect to the server and performing the signal analysis. The analysis was kept simple in order to limit delay.

    The result showed that it was possible to acquire real time signal with this method. The delay was negligible, both for the testing and for the game play.

    Showing that it is possible to play a game with muscle activation supports the idea of a motor that can be controlled automatically with muscle input. Future work should focus on understanding movement intent with respect to EMG and on analyzing multiple signals from different muscles at the same time.

  • 32.
    Andersson, Cajsa
    et al.
    KTH, School of Technology and Health (STH).
    Wallgren, Johanna
    KTH, School of Technology and Health (STH).
    Utvärdering av nya ät-träningsmetoder2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The Mandometer® Method helps people with eating disorders by teaching them how to eat ina ”correct” way by training with a product called Mandometer®. The users learn the correcteating behavior by receiving feedback from the display on the Mandometer® handheldcomputer on whether they eat too fast or too slow during the meal. Mando Group AB, thecompany which has developed the Mandometer® Method, has also created a computerprogram that works as a simulation of a meal with the Mandometer®. The purpose of thisstudy was to examine if training with the simulation could give the same effect as trainingwith Mandometer®. By letting a group of healthy testpersons practice with the simulationduring three weeks a result was given which clearly showed that the eating behavior of thetest persons had changed in the desired direction. The result indicates that there is a possibilityto add the simulation to the Mandometer® Method in the future. However, more testing anddeveloping of the program is first required.To improve Mandometer® further, a new version of the product has been developed wherethe handheld computer has been replaced by a cellphone and its functions by anapplication. The functionality and usability of the application was tested with the methodcognitive walkthrough, which showed that most of the pages of the application maintaineda high standard. With some adjustment of the pages where the usability was low, theapplication should be able to replace the old version of Mandometer® in the future.

  • 33.
    Andersson, Elin
    et al.
    KTH, School of Technology and Health (STH).
    Filipsson, Emma
    KTH, School of Technology and Health (STH).
    Upphandling av medicintekniska produkter inom sjukvården i Sverige2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Since 1994, the Public Procurement Act has undergone changes aimed to improve the procurement process and promoting innovation. In order to promote innovation there are a number of government agencies that offer financial assistance, especially to small business with innovative ideas. Despite these efforts, newly established small businesses have difficulties entering the market.

    The study investigates whether changes have been made in the public procurement of medical devices with regard to price and quality prioritization. The priority criteria is presented by the contracting authority as percentage in the allocation criteria. The study is limited to in vitro diagnostic products contracting in Swedish healthcare between the years 2009 and 2015. All tenders, companies that apply for participation in procurement, were analyzed based on sales, number of employees and year of establishment with the purpose of evaluating differences between winning tenders and other tenders.

    The result shows that prioritization has been increasingly on price rather than the quality. Regarding the winning tenders the study shows that larger, more established companies dominates the market. Noteworthy is that this dominance has increased over theses last years. The increase may be due to a spiral effect that is created when winning tenders get an increased economic power. 

  • 34.
    Andersson, Frida
    KTH, School of Technology and Health (STH).
    Finite Element Modeling of Skull Fractures: Material model improvements of the skull bone in theKTH FE head model2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The main aim of this project was to develop a model for predicting skull fractures of a 50th percentile male, using a finite element head model developed at the Neuronics department of KTH, Royal Instituteof Technology. The skull bone is modeled as a three layered bone, where the outer and inner tables are modeled as shell elements, while the diploë is modeled by two layers of solid elements. The material model of the tables was changed from the material model MAT_PLASTIC_KINEMATIC to a material model including a damage parameter to soften the damaged material and to enable ploting of the damage of the skull bone. Due to the coarse mesh of the FE head model the material model was not allowed to include any erosion, deleting element as they reach their ultimate strain. With these requests, two materials from the LS-DYNA material library seemed appropriate: material 81,MAT_PLASTICITY_WITH_DAMAGE and material 105, MAT_DAMAGE_2.

    To evaluate these materials and adjust the input parameters a dog bone FE model was developed and tension tests were simulated with this model, equivalent to tension tests performed on equally shaped skull bone specimens. The material simulating a behavior most similar to the behavior from the tension tests turned out to be material 81. This material model was then implemented in the full FE head model for further input parameter adjustment and validation. Four different cadaver experiments were simulated, with different impacting objects: sphere, box, cylinder and flat cylinder surface, and impacted areas of the head: vertex, temporo-parietal and frontal. The forces obtained in the simulations were compared to the forces of the cadaver experiments. The fracture prediction was based on the damage parameter, which could be plotted to visualize the areas where the ultimate strain was exceeded and thereby the area most likely to be fractured. This parameter was then compared to the documented fractures from the cadaver experiments.

    The result showed that using material 81 with the input parameter EPPFR=0.05 gave the overall most accurate forces and fracture predictions. The breaking stress, σB, did not affect the fractures significantly but a reduced σB resulted in reduction of the peak forces. The thickness of the diploë did not have any significant impact on the fracture occurrence, but a thinner diploë had a reducing impact on the peak forces as well.

  • 35.
    Andersson, Ida
    et al.
    KTH, School of Technology and Health (STH).
    Falck, Josefina
    KTH, School of Technology and Health (STH).
    Förstudie för utveckling av en höj- och sänkbar pall i operationsmiljö2011Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 36.
    Andersson, Ida
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering.
    Hedvall, Anders
    KTH, School of Technology and Health (STH), Medical Engineering.
    Relationships Between Skin Properties and Body Water Level2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A need for a quantitative method to determine body water level has been identified by a team of Clinical Innovation Fellows at the Centre for Technology in Medicine and Health (CTMH). A reliable way to determine body water level would bring great benefits to the healthcare sector, where no optimal method is available at the time of writing. A possible solution is a sensor that would measure alterations in skin properties due to changes in total body water. CTMH has had an idea of such a sensor, which is evaluated in this work. At an early stage of this evaluation process, it became clear that the research regarding correlations between skin properties and body hydration level was not sufficient to warrant the initiation of a sensor development process. Therefore, the main objective of this thesis became to investigate such correlations.

    An extensive literature review is presented, from which an experiment was developed. The experiment was performed on four human test subjects and involved measurements of skin thickness and elasticity parameters, before and after a weight loss of 3.2-3.7 % due to dehydration. The results showed clear decreases in skin thickness and indications of alterations in skin distensibility as well as in the skin’s immediate elastic response to applied negative pressure. It could also be seen that skin at different body sites does not respond in the same way - calves showed more distinct results than thighs and volar forearm.

    The material provided in this thesis encourages further studies of the correlation between the mentioned properties and total body water. If a predictable correlation can be found, a sensor development process could start. A reliable way to determine body water level would bring great benefits to the healthcare sector, where no optimal method is available at the time of writing.

  • 37.
    Andersson, Katarina
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Optimization of the Implantation Angle for a Talar Resurfacing Implant: A Finite Element Study2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Osteochondral lesions of the talus (OLTs) are the third most common type of osteochondral lesion and can cause pain and instability of the ankle joint. Episurf Medical AB is a medical technology company that develops individualized implants for patients who are suffering from focal cartilage lesions. Episurf have recently started a project that aims to implement their implantation technique in the treatment of OLTs.

    This master thesis was a part of Episurf’s talus project and the main goal of the thesis was to find the optimal implantation angle of the Episurf implant when treating OLTs. The optimal implantation angle was defined as the angle that minimized the maximum equivalent (von Mises) strain acting on the implant shaft during the stance phase of a normal gait cycle. It is desirable to minimize the strain acting on the implant shaft, since a reduction of the strain can improve the longevity of the implant.

    To find the optimal implantation angle a finite element model of an ankle joint treated with the Episurf implant was developed. In the model an implant with a diameter of 12 millimeters was placed in the middle part of the medial side of the talar dome. An optimization algorithm was designed to find the implantation angle, which minimized the maximum equivalent strain acting on the implant shaft. The optimal implantation angle was found to be a sagittal angle of 12.5 degrees and a coronal angle of 0 degrees. Both the magnitude and the direction of the force applied to the ankle joint in the simulated stance phase seemed to influence the maximum equivalent strain acting on the implant shaft.

    A number of simplifications have been done in the simulation of this project, which might affect the accuracy of the results. Therefore it is recommended that further, more detailed, simulations based on this project are performed in order to improve the result accuracy.

  • 38.
    Andersson, Katarina
    et al.
    KTH, School of Technology and Health (STH).
    Löfgren, Carita
    KTH, School of Technology and Health (STH).
    Partial Development of a Water Purification System Using Heat from Solar Energy, with Focus on Bangladesh2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 39.
    Andersson, Klara
    et al.
    KTH, School of Technology and Health (STH).
    Busch Paulsson, Esther
    KTH, School of Technology and Health (STH).
    Utvärdering av användarvänlighet hos hjälpmedel för ät-träning2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Mandometer® is a medical device, which assists patients with overweight and eating disorders to normalize their eating beahavior. Mandometer® has been developed by Mando Group AB and is used on Mandometer- and Mandolean Clinics in Sweden, USA and Australia in their treatment. A new version of Mandometer® has been recently developed, from generation four to generation five. It consists of a light scale and a mobile app, instead of a scale and a computer.  No previous study about the usability of the new version has been done. On behalf of Mando Group AB has such an evaluation been executed using questionnaires and conversations with both patients and healthy individuals. The results have been compiled and analyzed, and based on this a conclusion has been drawn. The usability is sufficient, but there are some deficiencies. This can be fixed by the suggested improvements and the written instruction manual. The result also shows that the development of the product is a clear improvement compared to the previous version.

  • 40.
    Andersson, Simon
    et al.
    KTH, School of Technology and Health (STH).
    Lundberg, Fabian
    KTH, School of Technology and Health (STH).
    Analys av resursbehovet per patient på akutmottagningen vid Karolinska Universitetssjukhuset Solna2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The staff of the emergency department at Karolinska Universitetssjukhuset Solna has in recent years experienced a higher workload, although the number of patients has not increased. Karolinska Universitetssjukhuset do not possess a set method to analyze the resource needs of different patient groups, and the difference between them. The project would thus give Karolinska Universitetssjukhuset a better understanding of different patients' resource needs in the form of a resource consumption model. This model was created through discussions with staff and analysis of data from Karolinska's internal data warehouse, Karda. From this a patient group distribution was created with the aim of grouping patients with similar resource needs. Time studies and surveys were conducted and compiled at the emergency department to generate important information. Analysis of the results obtained suggests that patients have, in recent years, become more ill and therefore more costly for the hospital. A resource consumption model has been created which can analyze and compare the patients' burden of care with one another by three parameters. These are priority and monitoring, period of residence and on-call salary increment. However, this model is not currently able to analyze all parameters simultaneously, only individually. In order to analyze parameters simultaneously the model and calculations would need to be revised. This could be a continuous study for further work in this specific area.  

  • 41.
    Anette, Kniberg
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems.
    Nokto, David
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems.
    A Benchmark of Prevalent Feature Selection Algorithms on a Diverse Set of Classification Problems2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Feature selection is the process of automatically selecting important features from data. It is an essential part of machine learning, artificial intelligence, data mining, and modelling in general. There are many feature selection algorithms available and the appropriate choice can be difficult. The aim of this thesis was to compare feature selection algorithms in order to provide an experimental basis for which algorithm to choose. The first phase involved assessing which algorithms are most common in the scientific community, through a systematic literature study in the two largest reference databases: Scopus and Web of Science. The second phase involved constructing and implementing a benchmark pipeline to compare 31 algorithms’ performance on 50 data sets.The selected features were used to construct classification models and their predictive performances were compared, as well as the runtime of the selection process. The results show a small overall superiority of embedded type algorithms, especially types that involve Decision Trees. However, there is no algorithm that is significantly superior in every case. The pipeline and data from the experiments can be used by practitioners in determining which algorithms to apply to their respective problems.

  • 42.
    Angelopoulos, A.
    et al.
    -.
    Apostolakis, A.
    -.
    Aslanides, E.
    -.
    Backenstoss, G.
    -.
    Bargassa, P.
    -.
    Behnke, O.
    -.
    Benelli, A.
    -.
    Bertin, V.
    -.
    Blanc, F.
    -.
    Bloch, P.
    -.
    Danielsson, Mats
    KTH, Superseded Departments, Physics.
    K 0–K̄0 mass and decay-width differences: CPLEAR evaluation1999In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 471, no 2, p. 332-338Article in journal (Refereed)
    Abstract [en]

    The CPT-violation parameters Re(δ) and Im(δ) determined recently by CPLEAR are used to evaluate the K0 mass and decay-width differences, as given by the difference between the diagonal elements of the neutral-kaon mixing matrix (M−iΓ/2). The results – GeV and GeV – are consistent with CPT invariance. The CPT invariance is also shown to hold within a few times 10−3–10−4 for many of the amplitudes describing neutral-kaon decays to different final states.

  • 43.
    Angelopoulos, Angelos
    et al.
    -.
    Apostolakis, A.
    -.
    Aslanides, E.
    -.
    Backenstoss, Gerhard
    -.
    Bargassa, P.
    -.
    Bee, C P.
    -.
    Behnke, O.
    -.
    Benelli, A.
    -.
    Bertin, V.
    -.
    Blanc, F.
    -.
    Danielsson, Mats
    KTH, Superseded Departments, Physics.
    Physics at CPLEAR2003In: Physics Reports, Vol. 374, no 3, p. 165-270Article in journal (Refereed)
    Abstract [en]

    LEAR offered unique opportunities to study the symmetries which exist between matter and antimatter. At variance with other approaches at this facility, CPLEAR was an experiment devoted to the study of CP, T and CPT symmetries in the neutral-kaon system. A variety of measurements allowed us to determine with high precision the parameters which describe the time evolution of the neutral kaons and their antiparticles, including decay amplitudes, and the related symmetry properties. Limits concerning quantum-mechanical predictions (EPR, coherence of the wave function) or the equivalence principle of general relativity have been obtained. An account of the main features of the experiment and its performances is given here, together with the results achieved.

  • 44.
    Angelopoulos, Angelos
    et al.
    -.
    Aslanides, E.
    -.
    Backenstoss, G.
    -.
    Bargassa, P.
    -.
    Behnke, O.
    -.
    Benelli, A.
    -.
    Bertin, V.
    -.
    Blanc, F.
    -.
    Bloch, P.
    -.
    Carlson, P.
    -.
    Danielsson, Mats
    KTH, Superseded Departments, Physics.
    K0⇋ K̄0 transitions monitored by strong interactions: a new determination of the K L–K S mass difference2001In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 503, no 1, p. 49-57Article in journal (Refereed)
    Abstract [en]

    The CPLEAR set-up (modified) has been used to determine the KL–KS mass difference by a method where neutral-kaon strangeness oscillations are monitored through kaon strong interactions, rather than semileptonic decays, thus requiring no assumptions on CPT invariance for the decay amplitudes. The result, Δm=(0.5343±0.0063stat±0.0025syst)×1010ℏ/s, provides a valuable input for CPT tests.

  • 45.
    Angelopoulos, Angelos
    et al.
    -.
    Locher, M P
    -.
    Markushin, V E
    -.
    Danielsson, Mats
    KTH, Superseded Departments, Physics.
    Dispersion relation analysis of the neutral kaon regeneration amplitude in carbon1999In: The European Physical Journal C-Particles and Fields, ISSN 434-6044, Vol. 10, no 1, p. 19-25Article in journal (Refereed)
    Abstract [en]

    We apply a forward dispersion relation to the regeneration amplitude for kaon scattering on 12" style="position: relative;" tabindex="0" id="MathJax-Element-1-Frame" class="MathJax">12C using all available data. The CPLEAR data at low energies allow the determination of the net contribution from the subthreshold region which turns out to be much smaller than earlier evaluations, solving a long standing puzzle.

  • 46.
    Anthony, Diana
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems.
    Creating an Individualized Predictive Model of PAO2 and PACO2 Changes During Voluntary Static Apnea for Sedentary Subjects2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The primary aim of this study was to fill a gap in the literature in understanding maximal BH in untrained, non-divers by generating a predictive numerical model for PAO2 and PACO2 throughout BH. There have been little to no previous attempts at explicitly characterizing the influence of impermanent personal or environmental factors on PAO2 or PACO2 at BH breakpoint. The metabolic human consumption of O2 and production of CO2 as measured through alveolar partial pressures was observed over time during a voluntary maximum breath-hold for 18 members of the general population. The coefficient of determination was used to determine accuracy of the model in fitting participants’ BH data from this experiment. The volume of the last inhalation pre-BH, time to subjective breakpoint, and breath-to-breath calculated respiratory exchange ratio (RER) were identified as the most influential combination of key variables that improved PAO2 model fit (from R2 = 0.8591 to R2 = 0.8840). Clustering methods coupled with two sample t-tests or ANOVA were then used to identify survey responses most correlated to inter-BH similarities. These were barometric pressure, age, height, weight, resting HR, smoker/ freediver/scuba experience, and weekly frequency of engaging in physical exercise. The model was validated on testing data from an experienced free-diver, from non-rebreathing trials of a sample of the participants, and from simulated dives of 5 participants from research in the Environmental Physiology Department of Karolinska in 1994 [1]. It has been suggested that the presented model can be a valuable tool in developing safer free diving practices. Furthermore, interesting trends in continuous HR, starting PACO2 values, and O2 consumption were observed and analyzed using statistical analysis. Findings were discussed with connection to the underlying physiological principles that might explain the results obtained.

  • 47. Anurag,
    et al.
    Moosavi, S. R.
    Rahmani, A. -M
    Westerlund, T.
    Yang, Geng
    KTH, School of Information and Communication Technology (ICT), Industrial and Medical Electronics.
    Liljeberg, P.
    Tenhunen, H.
    Pervasive health monitoring based on internet of things: Two case studies2015In: Proceedings of the 2014 4th International Conference on Wireless Mobile Communication and Healthcare - "Transforming Healthcare Through Innovations in Mobile and Wireless Technologies", MOBIHEALTH 2014, 2015, p. 275-278Conference paper (Refereed)
    Abstract [en]

    With the continuous evolution of wireless sensor networks and Internet of Things (IoT) various aspects of life will benefit. IoT based pervasive healthcare system has potential to provide error free medical data and alerting system in critical conditions with continuous monitoring. The system will minimize the need of dedicated medical personnel for patient monitoring and help the patients to lead a normal life besides providing them with high quality medical service. In this paper, we provide the implementation of IoT-based architectures for remote health monitoring based on two popular wireless technologies, Wi-Fi and ZigBee. We analyse the two architectures with the aim of identifying their pros and cons and discuss suitability of mentioned wireless communication technologies for different healthcare application domains.

  • 48. Apostolakis, A
    et al.
    Aslanides, E.
    -.
    Backenstoss, G.
    -.
    Bargassa, P.
    -.
    Behnke, O.
    -.
    Benelli, A.
    -.
    Bertin, V.
    -.
    Blanc, F.
    -.
    Bloch, P.
    -.
    Carlson, P.
    KTH, School of Engineering Sciences (SCI).
    Danielsson, Mats
    KTH, Superseded Departments, Physics.
    A determination of the CP violation parameter η+- from the decay of strangeness-tagged neutral kaons1999In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 458, no 4, p. 545-552Article in journal (Refereed)
    Abstract [en]

    LEAR offered unique opportunities to study the symmetries which exist between matter and antimatter. At variance with other approaches at this facility, CPLEAR was an experiment devoted to the study of CP, T and CPT symmetries in the neutral-kaon system. A variety of measurements allowed us to determine with high precision the parameters which describe the time evolution of the neutral kaons and their antiparticles, including decay amplitudes, and the related symmetry properties. Limits concerning quantum-mechanical predictions (EPR, coherence of the wave function) or the equivalence principle of general relativity have been obtained. An account of the main features of the experiment and its performances is given here, together with the results achieved.

  • 49.
    Apostolakis, A.
    et al.
    -.
    Aslanides, E.
    -.
    Backenstoss, G.
    -.
    Bargassa, P.
    -.
    Behnke, O.
    -.
    Benelli, A.
    -.
    Bertin, V.
    -.
    Blanc, F.
    -.
    Bloch, P.
    -.
    Carlson, P.
    Danielsson, Mats
    KTH, Superseded Departments, Physics.
    Measurement of the energy dependence of the form factor f+ in K 0 e3 decay2000In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 473, no 1, p. 186-192Article in journal (Refereed)
    Abstract [en]

    Neutral-kaon decays to πeν were analysed to determine the q2 dependence of the K0e3 electroweak form factor f+. Based on 365612 events, this form factor was found to have a linear dependence on q2 with a slope λ+=0.0245±0.0012stat±0.0022syst.

  • 50.
    Arfaoui, Yousef K.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Evaluation of a new instrument for measuring segmented radial force of SE-stents implemented in the LGF2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Endovascular surgery is a relatively new, rapidly growing, clinical technique and research area. A new endovascular tool has been developed by Endovascular Development AB, the Liungman Guidewire Fixator (LGF) that secures the distal position of a guidewire. The design of the LGF resembles a nitinol (Nickel-Titanium) stent and exerts a radial force against the blood vessel wall. It is desirable to have a well-founded understanding of all the mechanical characteristics of the product from a medical technology safety perspective.

     

    There are different methods for uniformly measure the radial force of an object, i.e. where one single total radial force represents the entire object.

    This report investigates the possibility for segmented radial force measurement by the development of a new measuring instrument. A prototype of the measuring instrument has been produced to test if the proposed method can be implemented or not.

     

    The prototype has been designed, developed and constructed to measure the radial force of individual segments of the stent. The stent segments were created using iris diaphragms and their resistance to radial change were measured using strain gauges. The concept was to measure the radial force differences between each segment with respect to the diameter of the stent. The results show a large and high intensity variation of data due to the strain gauge application. The variation is due to disturbances and flaws in the manufacturing process. On the other hand, one can see that the values for the radial forces of the segments for them different LGFs provide reasonable magnitudes. Some experiments also presents results similar to previous experiments. However, at the same time, no statistically significant conclusion can be drawn. The concept and the theory should work if the errors are changed. In summary, the proposal is to further develop the prototype and complement the experiment using finite element analysis.

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