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  • 1.
    Ahmed, Mobyen Uddin
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Fotouhi, Hossein
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Köckemann, Uwe
    Örebro University, Sweden.
    Lindén, Maria
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Tomasic, Ivan
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Tsiftes, Nicolas
    RISE SICS, Stockholm, Sweden.
    Voigt, Thiemo
    RISE SICS, Stockholm, Sweden.
    Run-Time Assurance for the E-care@home System2018In: Lecture Notes of the Institute for Computer Sciences, Social-Informatics and Telecommunications Engineering, LNICST, Volume 225, 2018, p. 107-110Conference paper (Refereed)
    Abstract [en]

    This paper presents the design and implementation of the software for a run-time assurance infrastructure in the E-care@home system. An experimental evaluation is conducted to verify that the run-time assurance infrastructure is functioning correctly, and to enable detecting performance degradation in experimental IoT network deployments within the context of E-care@home.

  • 2.
    Carmegren, E.
    et al.
    Mälardalen University.
    Åstrand, Elaine
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Tomasic, Ivan
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Dependability Evaluation of an Online Pupillometry-based Feedback System for Optimized Training2022In: 2022 45th Jubilee International Convention on Information, Communication and Electronic Technology, MIPRO 2022 - Proceedings, Institute of Electrical and Electronics Engineers Inc. , 2022, p. 327-332Conference paper (Refereed)
    Abstract [en]

    The online pupillometry-based feedback system is intended as a cognitive training and rehabilitation system developed at Mälardalen University. The purpose of the system is to engage a person in a cognitive computer task whose difficulty is adjusted in real time depending on the person's cognitive load. Previous research has uncovered a significant correlation between cognitive load and pupil dilation, suggesting that electroencephalogram usage for estimating cognitive load can be eliminated. The online pupillometry-based feedback system is measuring the pupil-diameter in real time to classify cognitive load using a neural network. The classification of cognitive load is used to modulate the difficulty level of the cognitive task, with the purpose of challenging the participant and to optimize the cognitive training. At the current state the system is fully integrated, but possesses no fault-tolerant features to produce a long-term reliable service. This paper proposes a fault-tolerant architecture for the online pupillometry-based feedback system, for which internal repairs and failure rates are modeled using continuous-time Markov chains. The results show adequacy of the extended architecture, assuming slightly optimistic failure rates. Even though the system is specific, the reliability approach presented can be applied on other medical devices and systems. 

  • 3.
    Fotouhi, Hossein
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Vahabi, Maryam
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Tomasic, Ivan
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Petrovic, Nikola
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Björkman, Mats
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Lindén, Maria
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems. ES (Embedded Systems).
    IPv6 connectivity in eHealth IoT networks2018In: Medicinteknikdagarna 2018 MTD 2018, Umeå, Sweden, 2018Conference paper (Refereed)
  • 4.
    Gardasevic, Gordana
    et al.
    University of Banja Luka, Bosnia-Herzegovina.
    Fotouhi, Hossein
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Tomasic, Ivan
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Vahabi, Maryam
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Björkman, Mats
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Lindén, Maria
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    A Heterogeneous IoT-based Architecture for Remote Monitoring of Physiological and Environmental Parameters2018In: Lecture Notes of the Institute for Computer Sciences, Social-Informatics and Telecommunications Engineering, LNICST, Volume 225, 2018, p. 48-53Conference paper (Refereed)
    Abstract [en]

    A heterogeneous Internet of Things (IoT) architecture for remote health monitoring (RHM) is proposed, that employs Bluetooth and IEEE 802.15.4 wireless connectivity. The RHM system encompasses Shimmer physiological sensors with Bluetooth radio, and OpenMote environmental sensors with IEEE 802.15.4 radio. This system architecture collects measurements in a relational database in a local server to implement a Fog node for fast data analysis as well as in a remote server in the Cloud. 

  • 5.
    Lešin, Antonella
    et al.
    University Hospital of Split, Split, Croatia.
    Mikić, Ivana Medvedec
    University of Split School of Medicine and University Hospital of Split, Split, Croatia.
    Bandić, Ružica
    University of Split School of Medicine, Split, Croatia.
    Vodanović, Katarina
    University of Split School of Medicine, Split, Croatia.
    Kekez, Ivna Vuković
    University of Split School of Medicine, Split, Croatia.
    Bečić, Tina
    University Hospital of Split, Split, Croatia.
    Tomasic, Ivan
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Vukojević, Katarina
    University of Split School of Medicine, Split, Croatia.
    Govorko, Danijela Kalibović
    University of Split School of Medicine and University Hospital of Split, Split, Croatia.
    Wireless ECG device for heart rhythm monitoring during dental extractions-a pilot study2021In: 2021 6th International Conference on Smart and Sustainable Technologies (SpliTech), 2021, p. 1-7Conference paper (Refereed)
    Abstract [en]

    Wireless electrocardiogram (ECG) monitoring devices are useful for detecting heart rhythm disorders and provide insight into the patient’s medical condition. Dental procedures produce fear, stress and anxiety and could trigger underlying, unrecognized cardiovascular disorders. In our pilot study, negative P-wave and discordant final oscillation occurred in all four phases of the procedure in nine out of twelve patients. Tachycardia occurred during the anaesthetic application in 50% of patients who received local infiltration anaesthesia group and 33% of patients from the inferior alveolar nerve block group, and also during the extraction phase in 33% of patients from the local infiltration anaesthesia group. Our data suggest that cardiovascular changes due to dental procedures are seen even in healthy individuals. Routine patients’ screening with these devices during stress-inducing procedures could help identify those with unrecognized cardiovascular risk.

  • 6.
    Petrovic, Nikola
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Fotouhi, Hossein
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Tomasic, Ivan
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Björkman, Mats
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Lindén, Maria
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    A remote health monitoring system featuring relational databases2017In: Medicinteknikdagarna 2017 MTD 2017, Västerås, Sweden, 2017Conference paper (Refereed)
    Abstract [en]

    Remote health monitoring (RHM) through the use of wearable wireless sensors, has drawn a lot of attention from academia and industry in the last decade [1,2]. The aging population, increasing cost of health-care, and lack of human resources in healthcare, are the three key motivators for the development of RHM [3,4]. The RHM systems should reduce health care costs and improve care quality. How to ensure a reliable and secure data collection from sensor devices to stake holders in RHM systems, is an open research question. The most established data storage technology that can ensure the security and privacy of data is the relational database management systems (RDBMSs). Besides security, RDBMSs provide a number of additional convenient features like querying the data, indexing, backups, replication, but are however in general slower than storing the data directly in a file system. Presented is a RHM system with a RDBMS in its core. The system was developed for the needs of ESS-H research profile [5] at Mälardalen University, Sweden. We also present a comprehensive system design which covers all the needs for the RHM application. The system is composed of four main components: (I) Shimmer sensors [6], (II) data acquisition layer (LabVIEW or C#.NET program), (III) RDBMS, and (IV) web service and web interface. The system communicates with the Shimmer sensors over Bluetooth and collects measurements in a relational database, either through a C#.NET or a LabVIEW program. The web service and a web interface are both written in PHP and are running on the Apache HTTP Server. The end-user is able to observe either real-time data (i.e. with insignificant delay) or processed historical data on any web browser. The advantage of using the web interface instead of a desktop application is that it makes the presentation layer easily accessible and platform independent. The RDBMSs provide data security and privacy in addition to other convenient features. Therefore, it is beneficial to incorporate RDBMSs in RHM systems. However, the RDBMSs provide no solution for security and privacy issues in wireless communication which is another research problem.

  • 7.
    Petrovic, Nikola
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Tomasic, Ivan
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Lindén, Maria
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Risman, Per Olov
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Detection of Human Bodypart Abnormalities by Microwaves – A New Approach2019In: 42nd International Convention on Information and Communication Technology, Electronics and Microelectronics MIPRO 2019, 2019, p. 270-274Conference paper (Refereed)
    Abstract [en]

    We present modified antenna-like devices - applicators - for direct detection of internal inhomogeneities such as breast tumours and brain haemorrhages, at a frequency about 1 GHz. This direct detection provides the possibility of using a simple microwave generator and simple rectification and position registration of the received signals. Direct readouts are thus possible, without any massive computing resources as with tomographic imaging. The transmitting applicator is non-contacting and in free air close to the object. It generates an essentially quasistatic axial magnetic field which induces a circular electric field in the tissue. The receiving 3D contacting applicator contains a high-permittivity ceramic and is resonant. Its mode field provides the desired polarisation sensitivity and filters out the main electric field. The overall system sensitivity for detection of internal inhomogeneities is accomplished by optimised use of the orthogonality of the primary magnetic, induced electric, and diffracted electric fields. When developments are completed, the system will replace or complement existing commercial technologies at a low cost.

  • 8.
    Petterson, Hannes Nitz
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Rehnholm, Jonas
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Vikström, Samuel
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Åslund, Martin
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Åstrand, Elaine
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Tomasic, Ivan
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Iris identification using wavelet decomposition and gabor filter2020In: 2020 43rd International Convention on Information, Communication and Electronic Technology, MIPRO 2020 - Proceedings, Institute of Electrical and Electronics Engineers Inc. , 2020, p. 265-270Conference paper (Refereed)
    Abstract [en]

    Biometric authentication has seen a widespread increase in popularity as supporting technology has become common in mass produced consumer electronics. Like fingerprints, each individual has unique patterns in the iris, which makes it a common approach for implementing visual biometric authentication. The paper describes a novel system for extracting the iris pattern and using it for identification of people. The system uses Haar wavelet decomposition and 2D Gabor filtering to extract the pattern data. The pattern data is then used with bitwise XOR comparison for final identification matching. Instead of manually selecting parameters for the Gabor filter, a machine learning method called Particle Swarm Optimization was used. The parameters that gave the best matching result were then implemented in the filter design. The implemented system was evaluated on images obtained from 6 individuals in different settings. The evaluation showed that matching identification could be achieved for the database used. The prepossessing of images with Independent Component Analysis was also used to remove the reflections on the images but that did not improve the classification significantly. Still we were able to perfectly distinguish between the individuals. Further preprocessing and a larger training database would be required to get more general and robust results.

  • 9.
    Prkic, A.
    et al.
    University of Split, Croatia.
    Tomasic, Ivan
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Lesin, A.
    Clinical Hospital Center, Split, Croatia.
    Becic, T.
    Clinical Hospital Center, Split, Croatia.
    Govorko, D. K.
    University of Split, Croatia.
    Mikic, I. M.
    University of Split, Croatia.
    Using patch ECG device during lower third molar surgery2021In: International Journal of Information Systems and Supply Chain Management (IJISSCM), ISSN 1935-5726, E-ISSN 1935-5734, Vol. 10, no 4Article in journal (Refereed)
    Abstract [en]

    This study aimed to evaluate cardiac activity changes during lower third molar surgery concerning gender and anxiety levels. Thirty healthy subjects who required lower third molar surgery filled out Norman Corah dental anxiety scale (DAS) before surgery. A patch ECG device (Savvy, Institute ''Jožef Stefan'', Ljubljana, Slovenia) was applied to the patient to evaluate heart rate (HR) and heart rhythm. These parameters were assessed in 8 different intervals. Periods of the highest mean HR values-incision and flap elevation compared to the period with minimal mean HR values-during suturing showed statistical significance difference (p<0.05). The most common outstanding ECG finding was sinus tachycardia, especially in anxious compared to non-anxious patients. Extraction difficulty score was correlated with the procedure duration time and with the abnormal ECG findings in the period of tooth extraction. Significant cardiac activity changes are detected during surgery. Physiological manifestations of anxiety may be evaluated successfully using a patch ECG device. Copyright 

  • 10. Rashkovska, A.
    et al.
    Depolli, M.
    Tomasic, Ivan
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Avbelj, V.
    Trobec, R.
    Medical-grade ECG sensor for long-term monitoring2020In: Sensors, E-ISSN 1424-8220, Vol. 20, no 6, article id 1695Article in journal (Refereed)
    Abstract [en]

    The recent trend in electrocardiogram (ECG) device development is towards wireless body sensors applied for patient monitoring. The ultimate goal is to develop a multi-functional body sensor that will provide synchronized vital bio-signs of the monitored user. In this paper, we present an ECG sensor for long-term monitoring, which measures the surface potential difference between proximal electrodes near the heart, called differential ECG lead or differential lead, in short. The sensor has been certified as a class IIa medical device and is available on the market under the trademark Savvy ECG. An improvement from the user’s perspective—immediate access to the measured data—is also implemented into the design. With appropriate placement of the device on the chest, a very clear distinction of all electrocardiographic waves can be achieved, allowing for ECG recording of high quality, sufficient for medical analysis. Experimental results that elucidate the measurements from a differential lead regarding sensors’ position, the impact of artifacts, and potential diagnostic value, are shown. We demonstrate the sensors’ potential by presenting results from its various areas of application: medicine, sports, veterinary, and some new fields of investigation, like hearth rate variability biofeedback assessment and biometric authentication. 

  • 11.
    Risman, Per Olov
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Petrovic, Nikola
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Tomasic, Ivan
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Lindén, Maria
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    New work on radiofrequency electric and electromagnetic leakage hazards for operators safety assessments2019In: Medicinteknikdagarna 2019 MTD 2019, 2019Conference paper (Refereed)
    Abstract [en]

    Various medical and industrial equipment types with electric fields having frequencies in the range 13 to 40 MHz have a long history. The relative simplicity of the generators and applicators (i.e. the assembly which is adapted for the treatment) have led to equipment manufacturing by many small companies having insufficient knowledge about human exposure hazards. The international regulations on maximum allowed exposure are not well-developed and mainly concern limits of the measured electric field, so-called reference levels, which are set to low values considered to be safe under all possible conditions. – Quite some scientific work on the field characteristics has been carried out since the 1970’s, the goal in many cases having been to motivate further research grants rather than assisting industry in improving safety by proposing more detailed regulations. In particular, researchers have used the electric field strengths as measured, without consideration of the field curvature and decay rate from the equipment, and by also using a too simplistic approach to the “power flux density” of the field emission. – As a consequence of the above, it is estimated that over 90 % of today’s operational equipment does not fulfill these simple regulations. In spite of that, very few incidents or accidents are reported. – New ongoing work by the International Electrotechnical Commission (IEC; committee 27) is now explaining this. The work is based on advanced numerical modelling of typical kinds of equipment and humans in different postures of arms and hands. Some results will be demonstrated and indicate that from five to more than twenty times stronger fields can be accepted under conditions of limited direct access to the energised equipment parts such as electrodes and rails, and proper design of the system grounding.

  • 12.
    Sović, J.
    et al.
    University of Zagreb, Croatia.
    Šegović, S.
    University of Zagreb, Croatia.
    Tomašić, Ivan
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Pavelić, B.
    University of Zagreb, Croatia.
    Šutej, I.
    University of Zagreb, Croatia.
    Anić, I.
    University of Zagreb, Croatia.
    Antibiotic administration along with endodontic therapy in the republic of Croatia: A pilot study2020In: Acta Stomatologica Croatica, ISSN 0001-7019, E-ISSN 1846-0410, Vol. 54, no 3, p. 314-321Article in journal (Refereed)
    Abstract [en]

    Objective: To evaluate the type and the frequency of antibiotic prescribing along with endodontic therapy in Croatia. The aim is, also, to assess the attitudes of Croatian doctors towards endodontic treatment of patients at risk of developing bacterial endocarditis. Material and methods: Data were collected by a survey questionnaire. Results: 8.4% of the examined practitioners stated that they prescribe antibiotics often, and 91.6% of them stated that they prescribed them never/ very rarely/rarely. Most of them (41%) prescribe antibiotics once or twice a month, 32.5% once or twice in several months and 20.5% once or twice a week. The most commonly used antibiotic was penicillin with clavulanic acid. Also, 26.2% of examined practitioners prescribed antibiotics for gangrene pulp, 51.2% of them for localized acute apical periodontitis without swelling, 85% of them for cellulitis, 75% of them for fever and enlarged lymph nodes, 16.9% of them for tooth with fistula and 94.1% of them for prophylaxis of infectious endocarditis. According to the results of study, 54.4% of dental practitioners did not prescribe antibiotics without intervention on susceptible tooth; 76% of participants often/almost always/ always accepted endodontic treatment of patients requiring antibiotic prophylaxis to prevent infectious endocarditis, and 96.7% of participants indicated they were familiar with recent instructions for antibiotic prophylaxis. Conclusion: These findings point to inappropriate use of antibiotics in the practice of 83 dental practitioners questioned regarding the frequency of administration and indications. The most commonly used antibiotic was penicillin with clavulanic acid. A high percentage of surveyed practitioners stated that they were familiar with recent instructions for antibiotic prophylaxis. They also stated that they performed endodontic procedures on patients who were at risk of bacterial endocarditis. There is a noticeable need for targeted continuing education of dental practitioners in the Republic of Croatia. 

  • 13.
    Tomasic, Ivan
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Andersson, A.
    Chalmers University, Gothenburg, Sweden.
    Funk, Peter
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Mixed-Effect Models for the Analysis and Optimization of Sheet-Metal Assembly Processes2017In: IEEE Transactions on Industrial Informatics, ISSN 1551-3203, E-ISSN 1941-0050, Vol. 13, no 5, p. 2194-2202, article id 7857795Article in journal (Refereed)
    Abstract [en]

    Assembly processes can be affected by various parameters, which is revealed by the measured geometrical characteristics (GCs) of the assembled parts deviating from the nominal values. Here, we propose a mixed-effect model (MEM) application for the purposes of analyzing variations in assembly cells, as well as for screening the input variables and characterization. MEMs make it possible to take into account statistical dependencies that originate from repeated measurements on the same assembly. The desirability functions approach was used to describe how to find corrective or control actions based on the fitted MEM. Objectives: To examine the usefulness of the MEM between the positions of the in-going parts as the input controllable variables and the measured GCs as the outputs. Methods: The data from 34 car frontal cross members (each measured three times) were experimentally collected in a laboratory environment by intentionally changing the positions of the in-going parts, assembling the parts, and subsequently measuring their GCs. A single MEM that completely describes the assembly process was fitted between the GCs and the positions of the in-going parts. Results: We present a modeling technique that can be used to establish which measured GCs are influenced by which controllable variables, and how this occurs. The fitted MEM shows evidence that the variability of some GCs changes over time. The natural variation in the system (i.e., unmodeled variations) is about two times larger than the variation between the assembled cross members. We also present two cases that demonstrate how to use the fitted MEM desirability functions to find corrective or control actions. Conclusion: MEMs are very useful tools for analyzing the assembly processes for car-body parts, which are nonlinear processes with multiple inputs and multiple correlated outputs. MEMs can potentially be applied in numerous industrial processes, since modern manufacturing plants measure all important process variables, which is the sole prerequisite for MEMs applications. 

  • 14.
    Tomasic, Ivan
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Avbelj, V.
    Jožef Stefan Institute, Ljubljana, Slovenia .
    Trobec, R.
    Jožef Stefan Institute, Ljubljana, Slovenia .
    Smart wireless sensor for physiological monitoring2015In: Studies in Health Technology and Informatics, vol. 211, 2015, p. 295-301Conference paper (Refereed)
    Abstract [en]

    Presented is a wireless body sensor capable of measuring local potential differences on a body surface. By using on-sensor signal processing capabilities, and developed algorithms for off-line signal processing on a personal computing device, it is possible to record single channel ECG, heart rate, breathing rate, EMG, and when three sensors are applied, even the 12-lead ECG. The sensor is portable, unobtrusive, and suitable for both inpatient and outpatient monitoring. The paper presents the sensor's hardware and results of power consumption analysis. The sensor's capabilities of recording various physiological parameters are also presented and illustrated. The paper concludes with envisioned sensor's future developments and prospects.

  • 15.
    Tomasic, Ivan
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Erdem, Ilker
    Chalmers University of Technology, Sweden.
    Rahman, Hamidur
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Andersson, Alf
    Volvo Car Corporation Manufacturing Engineering, Sweden.
    Funk, Peter
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Sources of Variation Analysis in Fixtures for Sheet Metal Assembly Process2016In: Swedish Production Symposium 2016 SPS 2016, 2016Conference paper (Refereed)
    Abstract [en]

    The assembly quality is affected by various factors within which fixture variations are the most important. For that reason significant research on fixture variations has already been done. In this work we propose a linear mixed models (LMMs) application for the purpose of analyzing sources of variation in the fixture Objective: To estimate the strength of influences of different sources of variation on the control and assembly fixtures. The variables considered are: time, operator, default pin positions, shifts from the default pin positions . Methods: The data was collected through assembly and measurement for repeatability and experimental corrective actions. We use LMMs to model the relation between features measured on the assembled parts and the input variables of interest. The LMMs allow taking into account the correlation of observations contained in the dataset. We also use graphical data presentation methods to explore the data. Results: The expected results are the strengths of influences of the individual variables considered, and the pairwise interactions of between the variables, on the assembled parts variations.

  • 16.
    Tomasic, Ivan
    et al.
    Jozef Stefan Institute, Ljubljana, Slovenia.
    Frljak, Sabina
    University Medical Center, Ljubljana, Slovenia.
    Trobec, Roman
    Jozef Stefan Institute, Ljubljana, Slovenia.
    Estimating the universal positions of wireless body electrodes for measuring cardiac electrical activity2013In: IEEE Transactions on Biomedical Engineering, ISSN 0018-9294, E-ISSN 1558-2531, Vol. 60, no 12, p. 3368-3374, article id 6574211Article in journal (Refereed)
    Abstract [en]

    A methodology is presented for estimating the wireless body electrode (WE) positions and for calculating the linear transformations that enable the synthesis of a 12-lead ECG or a multichannel ECG from three WEs, which in turn simplifies and improves the acquisition of ECGs. We present, compare, and evaluate three approaches to the synthesis: fully personalized, fully universal, and combined with universal leads and personalized transformations. The evaluation results show that WEs are an acceptable alternative to the standard 12-lead ECG device for patients with chronic myocardial ischemia, if either the fully personalized or combined approach is used. The median correlation coefficients are all higher than 0.94 and 0.92 for the fully personalized and combined approaches, respectively. The corresponding kappa and percentual diagnostic agreements between the synthesized and target 12-lead ECGs are 0.88 (95%) and 0.83 (92%), respectively. The evaluation additionally shows that the personalization of the transformations has more impact on the quality of the synthesized ECGs than the personalization of the WEs' positions.

  • 17.
    Tomasic, Ivan
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Khosraviani, K.
    CNet Svenska AB, Stockholm, Sweden.
    Rosengren, P.
    CNet Svenska AB, Stockholm, Sweden.
    Jornten-Karlsson, M.
    AstraZeneca R and D, Gothenburg, Sweden.
    Lindén, Maria
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Enabling IoT based monitoring of patients' environmental parameters: Experiences from using OpenMote with OpenWSN and Contiki-NG2018In: 2018 41st International Convention on Information and Communication Technology, Electronics and Microelectronics, MIPRO 2018 - Proceedings, 2018, p. 330-334Conference paper (Refereed)
    Abstract [en]

    Remote health monitoring can be leveraged by the IoT paradigm. We tested OpenMotes, state-of-the-art IoT devices featuring IEEE 802.15.4 protocol, with Contiki-NG and OpenWSN, two of the most popular IoT operating systems, for the purpose of obtaining data from the OpenMote's sensors. The procedure is not strait forward and requires additional programing of the operating systems. All the steps necessary to make the OpenMote work with Contiki-NG are presented in detail. We also describe how to use Copper Firefox add-on to access the sensors data over CoAP, as well as how to design a functional web interface in Node-RED for the sensors data. 

  • 18.
    Tomasic, Ivan
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Petrovic, Nikola
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Fotouhi, Hossein
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Björkman, Mats
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Lindén, Maria
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    IoT enabled monitoring of patients’ environmental parameters supported by OpenWSN, OpenMote, and relational databases2018In: Medicinteknikdagarna 2018 MTD 2018, 2018Conference paper (Refereed)
  • 19.
    Tomasic, Ivan
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Petrovic, Nikola
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Fotouhi, Hossein
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Lindén, Maria
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Björkman, Mats
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Data flow and collection for remote patients monitoring: From wireless sensors through a relational database to a web interface in real time2018In: IFMBE Proceedings, Springer Verlag , 2018, Vol. 65, p. 89-92Conference paper (Refereed)
    Abstract [en]

    A reliable, secure, and real-time data collection from sensor devices to the end-user is an open research problem. Many research works have been focusing on the wireless communication level to obtain quality of service. This paper widens the problem, and provides a comprehensive system design, where it covers all the elements in a remote health monitoring application. The system collects measurements in a relational database, either through a C#.NET or a LabVIEW program. The end-user is able to observe either real-time data (i.e. with insignificant delay) or processed historical data on any web browser. We have shown that the inclusion of the relational database may impose a need for the data to be buffered before inserting into the database within a single transaction, but the buffering does not entail delays bigger than 50 ms. 

  • 20.
    Tomasic, Ivan
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Petrovic, Nikola
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Lindén, Maria
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Rashkovska, A.
    Jolef Stefan Inst, Dept Inst Commun Syst, Ljubljana, Slovenia..
    Comparison of publicly available beat detection algorithms performanances on the ECGs obtained by a patch ECG device2019In: 2019 42ND INTERNATIONAL CONVENTION ON INFORMATION AND COMMUNICATION TECHNOLOGY, ELECTRONICS AND MICROELECTRONICS (MIPRO) / [ed] Koricic, M Butkovic, Z Skala, K Car, Z CicinSain, M Babic, S Sruk, V Skvorc, D Ribaric, S Gros, S Vrdoljak, B Mauher, M Tijan, E Pale, P Huljenic, D Grbac, TG Janjic, M, IEEE , 2019, p. 275-278Conference paper (Refereed)
    Abstract [en]

    Eight ECG beat detection algorithms, from the PhysioNet's WFDR and Cardiovascular Signal toolboxes, were tested on twenty measurements, obtained by the Savvy patch ECG device, for their accuracy in beat detection. On each subject, one measurement is obtained while sitting and one while running. Each measurement lasted from thirty seconds to one minute. The measurements obtained while running were more challenging for all the algorithms, as most of them almost perfectly detected all the beats on the measurements obtained in sitting position. However, when applied on the measurements obtained while running, all the algorithms have performed with decreased accuracy. Considering overall percentage of the faulty detected peaks, the four best algorithms were jqrs, from the Cardiovascular Signal Toolbox, and ecgpuwave, gqrs, and wqrs, from the WEDB Toolbox, with percentages of faulty detected beats 1.7, 2.3, 2.9, and 3, respectively.

  • 21.
    Tomasic, Ivan
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Petrovic, Nikola
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Lindén, Maria
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Rashkovska, A.
    Jožef Stefan Institute, Department of Communication Systems, Ljubljana, Slovenia.
    Comparison of publicly available beat detection algorithms performances on the ECGs obtained by a patch ECG device2019In: 2019 42nd International Convention on Information and Communication Technology, Electronics and Microelectronics, MIPRO 2019 - Proceedings, Institute of Electrical and Electronics Engineers Inc. , 2019, p. 275-278Conference paper (Refereed)
    Abstract [en]

    Eight ECG beat detection algorithms, from the PhysioNet's WFDB and Cardiovascular Signal toolboxes, were tested on twenty measurements, obtained by the Savvy patch ECG device, for their accuracy in beat detection. On each subject, one measurement is obtained while sitting and one while running. Each measurement lasted from thirty seconds to one minute. The measurements obtained while running were more challenging for all the algorithms, as most of them almost perfectly detected all the beats on the measurements obtained in sitting position. However, when applied on the measurements obtained while running, all the algorithms have performed with decreased accuracy. Considering overall percentage of the faulty detected peaks, the four best algorithms were jqrs, from the Cardiovascular Signal Toolbox, and ecgpuwave, gqrs, and wqrs, from the WFDB Toolbox, with percentages of faulty detected beats 1.7, 2.3, 2.9, and 3, respectively. 

  • 22.
    Tomasic, Ivan
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Prkic, A.
    Private dental practice, Zagreb, Croatia.
    Lesin, A.
    University Hospital of Split, Department of Maxillofacial Surgery, Split, Croatia.
    Govorko, D. K.
    University Hospital of Split, Department of Maxillofacial Surgery, Split, Croatia.
    Tomasic, N.
    Karolinska University Hospital, Stockholm, Sweden.
    Mikic, I. M.
    University Hospital of Split, Department of Maxillofacial Surgery, Split, Croatia.
    Heart Rate Variability Monitoring with Savvy ECG Sensor During Dental Surgery2023In: ICT Electron. Conv., MIPRO - Proc., Institute of Electrical and Electronics Engineers Inc. , 2023, p. 363-368Conference paper (Refereed)
    Abstract [en]

    Surgical procedures are accompanied with anxiety and stress for both patients and surgeons. This paper investigates the utility of various heart rate variability parameters, estimated from Savvy patch ECG recordings, obtained on patients during surgical extraction of impacted lower third molars under local anesthesia, to estimate psychological state of the patient, as well as pain levels, in real time. This could be particularly beneficial for patients with chronic conditions, such as cardiovascular diseases, that can deteriorate under psychophysical stress. Statistical analysis showed significant correlation between several heart rate variability parameters and changes in autonomous nervous system functionality. Additionally, there was a significant correlation between several heart rate variability parameters on one side, and patient reported anxiety, pain levels, and the procedure difficulty, on the other.

  • 23.
    Tomasic, Ivan
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Rahman, Hamidur
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Erdem, Ilker
    Chalmers University of Technology, Sweden.
    Andersson, Alf
    Volvo Car Corporation Manufacturing Engineering, Sweden.
    Funk, Peter
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Input-output Mapping and Sources of Variation Analysis in Fixtures for Sheet Metal Assembly Processes2016In: Swedish Production Symposium 2016 SPS 2016, 2016Conference paper (Refereed)
    Abstract [en]

    The assembly quality is affected by various factors within which fixture variations are the most important. For that reason an extensive research on fixture variations has already been done. In this work we propose a linear models (LMs) application for the purpose of analyzing sources of variation in the fixture as well as establishing a model between positions of ingoing parts and measured geometrical characteristics of the assemblies. Objectives: (1) To estimate the strengths of different sources of variation on the assembled parts. (2) Estimate a regression model between the positions of ingoing parts as inputs (that are defined by positions of pins holding them), and measured geometrical characteristics as outputs, that can be used to determine which measured characteristics are influenced by which input variable. Methods: The data was experimentally collected in a laboratory environment by intentionally changing positions of ingoing part, assembling the parts and subsequently measuring their geometrical characteristics. We use liner model to establish the relation between geometrical characteristics measured on the assembled parts, and the input variables of interest. Results: Presented is a modeling technique that can be used to establish which measured geometrical characteristics are influenced by input variables (i.e.pins’ positions) of interest. The natural variation in the system (i.e. not modeled variation) is quite high. The time passed between measurements has a significant influence on measured values.

  • 24.
    Tomasic, Ivan
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Rashkovska, A.
    Jožef Stefan Institute, Ljubljana, Slovenia.
    Trobec, R.
    Jožef Stefan Institute, Ljubljana, Slovenia.
    Lindén, Maria
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    The implications of the lead theory on the patch ECG devices positioning and measurement2019In: IFMBE Proceedings, Springer Verlag , 2019, no 1, p. 693-696Conference paper (Refereed)
    Abstract [en]

    Currently we are witnessing fast development of patch ECG devices, some of which have already been extensively evaluated and shown to be useful for detecting arrhythmias. The research about using the patch ECG devices for purposes other than arrhythmia detection has been scarce. The efficiency of patch electrocardiography for a specific purpose can depend on the devices location on the body surface. It is still an open question where to position the ECG patch devices, and should the position depend on the specific purpose and perhaps even be personalized. We present the lead theory of differential leads (ECG leads obtained by patch ECG devices) and discuss its implications on the patch ECG devices positioning on the body surface.

  • 25.
    Tomasic, Ivan
    et al.
    Jožef Stefan Institute, Ljubljana, Slovenia.
    Rashkovska, Aleksandra
    Jožef Stefan Institute, Ljubljana, Slovenia.
    Depolli, Matjaž
    Jožef Stefan Institute, Ljubljana, Slovenia.
    Using Hadoop MapReduce in a multicluster environment2013In: The 36th international convention on information and communication technology, electronics and microelectronics MIPRO 2013, 2013, Vol. Article number 6596280, p. 369-374Conference paper (Refereed)
    Abstract [en]

    Hadoop MapReduce has become one of the most popular tools for data processing. Hadoop is normally installed on a cluster of computers. When the cluster becomes undersized, it can be scaled by adding new computers and storage devices, but it can also be extended by real or virtual resources from another computer cluster. We present a utilization of the MapReduce paradigm on a Hadoop installation extended across two clusters connected over the Internet. We measured execution times of Map and Reduce tasks in a multicluster environment, and compared them to the corresponding times obtained while only computers from a single cluster are used. The results show that there might be a decrease inMapReduce performance depending on: the concrete data analyses application, the ratio of the number of local and remote computers, and connection bandwidth to remote computers. Additionally, the investigation suggests an upgrade to the Apache Hadoop MapReduce, making it more adjusted to the multicluster environment.

  • 26.
    Tomasic, Ivan
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems. Lund University, Sweden.
    Tomasic, Nikica
    Lund University, Sweden.
    Trobec, Roman
    Jozef Stefan Inst, Dept Commun Syst, Ljubljana, Slovenia..
    Krpan, Miroslav
    Univ Hosp Ctr, Dept Cardiol, Zagreb, Croatia..
    Kelava, Tomislav
    Univ Zagreb, Sch Med, Dept Physiol, Zagreb, Croatia..
    Continuous remote monitoring of COPD patients-justification and explanation of the requirements and a survey of the available technologies2018In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 56, no 4, p. 547-569Article, review/survey (Refereed)
    Abstract [en]

    Remote patient monitoring should reduce mortality rates, improve care, and reduce costs. We present an overview of the available technologies for the remote monitoring of chronic obstructive pulmonary disease (COPD) patients, together with the most important medical information regarding COPD in a language that is adapted for engineers. Our aim is to bridge the gap between the technical and medical worlds and to facilitate and motivate future research in the field. We also present a justification, motivation, and explanation of how to monitor the most important parameters for COPD patients, together with pointers for the challenges that remain. Additionally, we propose and justify the importance of electrocardiograms (ECGs) and the arterial carbon dioxide partial pressure (PaCO2) as two crucial physiological parameters that have not been used so far to any great extent in the monitoring of COPD patients. We cover four possibilities for the remote monitoring of COPD patients: continuous monitoring during normal daily activities for the prediction and early detection of exacerbations and life-threatening events, monitoring during the home treatment of mild exacerbations, monitoring oxygen therapy applications, and monitoring exercise. We also present and discuss the current approaches to decision support at remote locations and list the normal and pathological values/ranges for all the relevant physiological parameters. The paper concludes with our insights into the future developments and remaining challenges for improvements to continuous remote monitoring systems.

  • 27.
    Tomasic, Ivan
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Trobec, R.
    Department of Communication Systems, Jožef Stefan Institute, Ljubljana, Slovenia.
    Lindén, Maria
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Can the regression trees be used to model relation between ECG leads?2016In: Lecture Notes of the Institute for Computer Sciences, Social-Informatics and Telecommunications Engineering, LNICST, 2016, Vol. 169, p. 467-472Conference paper (Refereed)
    Abstract [en]

    Presented is a preliminary study that investigates regression trees application for the purpose of mapping relationship between three differential ECG leads and leads of the 12-lead ECG. The approach was evaluated on a single ECG measurement on which it was superior to two syntheses performed by universal and personalized linear transformations, in terms of correlation coefficients between the synthesized and measured leads. A prominent imperfection however is that the regression trees can output only a limited number of values equal to the number of leaf nodes. The paper indicates some ideas on how to overcome this deficiency.

  • 28.
    Tomasic, Ivan
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Trobec, R.
    Jožef Stefan Institute, Department of Communication Systems, Ljubljana, Slovenia.
    Lindén, Maria
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    State-Space versus Linear Regression Models between ECG Leads2021In: 2021 44th International Convention on Information, Communication and Electronic Technology, MIPRO 2021 - Proceedings, Institute of Electrical and Electronics Engineers Inc. , 2021, p. 357-362Conference paper (Refereed)
    Abstract [en]

    The first attempts to modeling relationships between electrocardiographic leads, were based on measuring lead vectors by using models of human torso (deterministic approach), and by estimating liner regression models between leads of interest (statistical models). Among the most recent attempts, one of the most prominent is the state-space models approach, because of better noise immunity compared to mean squared error estimated statistical models. This study uses state-space models to synthesize precordial leads and Frank leads, from leads I, II, and V1. The synthesis was evaluated with the linear correlation coefficient (CC) on 200 measurements from the Physionet's PTB diagnostic ECG database. The results show better performance of regression models (mean CC between 0.88 and 0.96) than the state-space models (mean CC between 0.78-0.86). The leads were not pre-aligned for the R-peaks, which can be the main cause for the lower performances of state-space models, as a previous study has also shown. Residual baseline wander (after filtering) was the dominant reason for not obtaining better synthesis results with both methods. 

  • 29.
    Tomasic, Ivan
    et al.
    Jožef Stefan Institute, Slovenia.
    Trobec, Roman
    Jožef Stefan Institute, Slovenia.
    Electrocardiographic systems with reduced numbers of leads - synthesis of the 12-lead ECG2014In: IEEE Reviews in Biomedical Engineering R-BME, ISSN 1937-3333, Vol. 7, p. 126-142, article id 6517463Article in journal (Refereed)
    Abstract [en]

    Systems with reduced numbers of leads that can synthesize the 12-lead ECG with an insignificant or a small loss of diagnostic information have been proposed. The advantage over standard 12-lead ECG systems is the smaller number of measurement sites (i.e., electrodes) and, consequently, fewer wires. In this article we review all the important systems with reduced numbers of leads together with the methodology for synthesizing the leads. The fundamental theoretical background necessary to understand the most important concepts related to the synthesis is included. The presented theoretical and experimental justifications for the synthesis show that it is not necessary to measure a large number of leads directly, because the standard 12-lead ECG and arbitrary additional leads can be synthesized. Various approaches to evaluating the synthesized 12-lead ECG are defined and explained, and a number of systems that synthesize 12-lead ECG are presented as they were introduced in the literature. We cover the developments and improvements from the 1940s to the present day. The systems are classified on the basis of the synthesis method used, the approach to the evaluation of the synthesized ECG (depending on the measurement sites used), and on the number and types of leads employed. Based on a detailed assessment of state-of-the-art systems, open problems and challenges are highlighted, while further developments of electrocardiographic systems are envisaged.

  • 30.
    Tomasic, Ivan
    et al.
    Jožef Stefan Institute, Ljubljana, Slovenia.
    Trobec, Roman
    Jožef Stefan Institute, Ljubljana, Slovenia.
    Magjarević, Ratko
    Department of Electronic Systems and Information Processing, Zagreb, Croatia.
    Principal component analysis of differential electrocardiographic leads - A contribution to the synthesis of ECGs2013In: IFMBE Proceedings, Volume 42, 2013, Vol. 42, p. 260-263Conference paper (Refereed)
    Abstract [en]

    The principal component analysis (PCA) is applied on juxtaposed average beats of unipolar and differential leads (DLs), obtained from 35-lead multichannel ECGs, for assessing proportions of cardiac electrical activity variance that the leads measure. It was shown that 93% of the total 35- lead measured variance can be explained by the first three principal components (PCs). An analysis of correlations between the ECG leads and thefirst three PCs shows that the leads employing electrodes further to the heart pick up less of the total ECG variance. It was also demonstrated that DLs with highest correlations to the first three PCs, coincide with the universal DLs selected by our previously published ECG synthesis algorithm: BDLSA. This enables the application of the PCA in the selection of optimal DLs combinations for the ECG synthesis. 

  • 31.
    Tomasic, Ivan
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Trobec, Roman
    Jožef Stefan Institute, Ljubljana, Slovenia.
    Rashkovska, Aleksandra
    Jožef Stefan Institute, Ljubljana, Slovenia.
    Lindén, Maria
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Impact of electrode misplacement on the accuracy of 12-lead ECG synthesized from differential leads2015In: 2015 38th International Convention on Information and Communication Technology, Electronics and Microelectronics, MIPRO 2015: Proceedings, 2015, Vol. Article number 7160296, p. 365-369Conference paper (Refereed)
    Abstract [en]

    The sensitivity to electrode misplacement of the 12-lead ECG, synthesized from differential leads, was analyzed by simulating the electrode misplacement, with a help from interpolated body surface potential maps. The electrodes forming optimal differential leads were independently moved only on the lines defined by gradient vectors, calculated on the integral body surface potential map, obtained from juxtaposed average beats for each of the 47 multichannel ECGs used in the study. The 12-lead ECGs were synthesizes from the simulated moved differential leads and compared to the ECGs synthesized from the nominal electrodes’ positions, by using correlation coefficients and RMSD. The results show that synthesized 12-lead ECGs are less accurate if electrodes with bigger associated gradients are misplaced, but also suggest that small displacements of up to 1 cm do not have a big influence on the synthesis quality. From the perspective of ECG synthesis, the presented methodology can be used to define an additional criterion for optimal triplets of differential leads selection, which will ensure that the differential lead triplet are optimal not only in terms of the quality of the synthesized leads, but also in terms of being minimally sensitive to electrode misplacement.

  • 32.
    Tomasic, Nikica
    et al.
    Lund Univ, Dept Clin Sci, Pediat, Klin Gatan 12, S-22184 Lund, Sweden.;Karolinska Univ Hosp, Dept Neonatol, Stockholm, Sweden.;Univ Zagreb, Dept Biol, Fac Sci, Zagreb, Croatia..
    Kotarsky, Heike
    Lund Univ, Dept Pathol, Lund, Region Skane, Sweden..
    Figueiredo, Rejane de Oliveira
    Folkhalsan Res Ctr, Helsinki, Finland..
    Hansson, Eva
    Lund Univ, Dept Clin Sci, Pediat, Klin Gatan 12, S-22184 Lund, Sweden..
    Morgelin, Matthias
    Lund Univ, Dept Clin Sci, Lund, Sweden..
    Tomasic, Ivan
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Kallijarvi, Jukka
    Folkhalsan Res Ctr, Helsinki, Finland.;Univ Helsinki, Fac Med, Stem Cells & Metab Res Program, Helsinki, Finland..
    Elmer, Eskil
    Lund Univ, Mitochondrial Med, Dept Clin Sci, Lund, Sweden..
    Jauhiainen, Matti
    Minerva Fdn, Natl Inst Hlth & Welf, Biomedicum 2U, Inst Med Res, Helsinki, Finland..
    Eklund, Erik A.
    Lund Univ, Dept Clin Sci, Pediat, Klin Gatan 12, S-22184 Lund, Sweden..
    Fellman, Vineta
    Lund Univ, Dept Clin Sci, Pediat, Klin Gatan 12, S-22184 Lund, Sweden.;Folkhalsan Res Ctr, Helsinki, Finland.;Univ Helsinki, Childrens Hosp, Helsinki, Finland..
    Fasting reveals largely intact systemic lipid mobilization mechanisms in respiratory chain complex III deficient mice2020In: Biochimica et Biophysica Acta - Molecular Basis of Disease, ISSN 0925-4439, E-ISSN 1879-260X, Vol. 1866, no 1, article id 165573Article in journal (Refereed)
    Abstract [en]

    Mice homozygous for the human GRACILE syndrome mutation (Bcs1l (c.A232G)) display decreased respiratory chain complex III activity, liver dysfunction, hypoglycemia, rapid loss of white adipose tissue and early death. To assess the underlying mechanism of the lipodystrophy in homozygous mice (Bcs1l(p.S)(78G)), these and wild-type control mice were subjected to a short 4-hour fast. The homozygotes had low baseline blood glucose values, but a similar decrease in response to fasting as in wild-type mice, resulting in hypoglycemia in the majority. Despite the already depleted glycogen and increased triacylglycerol content in the mutant livers, the mice responded to fasting by further depletion and increase, respectively. Increased plasma free fatty acids (FAs) upon fasting suggested normal capacity for mobilization of lipids from white adipose tissue into circulation. Strikingly, however, serum glycerol concentration was not increased concomitantly with free FM, suggesting its rapid uptake into the liver and utilization for fuel or gluconeogenesis in the mutants. The mutant hepatocyte mitochondria were capable of responding to fasting by appropriate morphological changes, as analyzed by electron microscopy, and by increasing respiration. Mutants showed increased hepatic gene expression of major metabolic controllers typically associated with fasting response (Ppargc1a, Fgf21, Cd36) already in the fed state, suggesting a chronic starvation-like metabolic condition. Despite this, the mutant mice responded largely normally to fasting by increasing hepatic respiration and switching to FA utilization, indicating that the mechanisms driving these adaptations are not compromised by the CIII dysfunction. Summary statement: Bcs1l mutant mice with severe CIII deficiency, energy deprivation and post-weaning lipolysis respond to fasting similarly to wild-type mice, suggesting largely normal systemic lipid mobilization and utilization mechanisms.

  • 33.
    Trobec, R.
    et al.
    Department of Communication Systems, Jožef Stefan Institute, Ljubljana, Slovenia.
    Jan, M.
    Department of Cardiovascular Surgery, University Medical Centre, Ljubljana, Slovenia.
    Lindén, Maria
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Tomasic, Ivan
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Detection and Treatment of Atrial Irregular Rhythm with Body Gadgets and 35-channel ECG2019In: 2019 42nd International Convention on Information and Communication Technology, Electronics and Microelectronics, MIPRO 2019 - Proceedings, Institute of Electrical and Electronics Engineers Inc. , 2019, p. 301-308Conference paper (Refereed)
    Abstract [en]

    The atrial irregular rhythm, often reflected in atrial fibrillation, undulation or flutter, is recognized as one of the major causes of brain stroke and entails an increased risk of thromboembolic events because it increases the likelihood of blood clots formation. Its early detection is becoming an increasingly important preventive measure. The paper presents a simple methodology for the detection of atrial irregular rhythm by ECG body gadget that can perform long-term measurements, e.g. several weeks or more. Multichannel ECG, on the body surface, gives a more detailed insight into the atrial activity in comparison to standard 12-lead ECG. The information from MECG is compared with single-channel patch ECG. The obtained results suggest that the proposed methodology could be useful in treatments of atrial irregular rhythm. One can obtain a reliable information about the time and duration of fibrillation events, or determine arrhythmic focuses and conductive pathways in heart atria, or study the effects of antiarrhythmic drugs on existing arrhythmias and on an eventual development of new types of arrhythmias. 

  • 34.
    Trobec, R.
    et al.
    Joef Stefan Institute, Ljubljana, Slovenia.
    Tomasic, Ivan
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Rashkovska, A.
    Joef Stefan Institute, Ljubljana, Slovenia.
    Avbelj, V.
    Joef Stefan Institute, Ljubljana, Slovenia.
    Lead theory of differential leads and synthesis of the standard 12-lead ECG2018In: SpringerBriefs in Applied Sciences and Technology, Springer Verlag , 2018, no 9783319593388, p. 77-100Chapter in book (Refereed)
    Abstract [en]

    In this chapter, the lead theory of differential leads is presented. A differential lead is an ECG lead obtained from two closely positioned electrodes on the body surface. It can be measured with an ECG body sensor. The theoretical background is needed to gain a formal and intuitive understanding of what is measured with differential leads, as well as to elaborate how the standard 12-lead ECG can be synthesized from three differential leads. The 12-lead ECG synthesis is based on the dipole volume source model. After introducing the dipole model, the Burger’s equation is derived and the concept of lead vector defined. We describe how to derive lead vectors from known heart vector and, vice versa, how to obtain the heart vector from known lead vectors. Then, the concepts of image surface and lead field are introduced, followed with a description of the lead field of a differential lead. Next, the theory and methods for ECG leads synthesis from differential leads is presented. The chapter concludes with a discussion on the evaluation and personalization of the synthesis. 

  • 35.
    Trobec, R.
    et al.
    Jožef Stefan Institute, Ljubljana, Slovenia.
    Tomasic, Ivan
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Rashkovska, A.
    Jožef Stefan Institute, Ljubljana, Slovenia.
    Depolli, M.
    Jožef Stefan Institute, Ljubljana, Slovenia.
    Avbelj, V.
    Jožef Stefan Institute, Ljubljana, Slovenia.
    Commercial ECG systems2018In: SpringerBriefs in Applied Sciences and Technology, Springer Verlag , 2018, no 9783319593388, p. 101-114Chapter in book (Refereed)
    Abstract [en]

    Besides the standard 12-lead ECG and the Holter monitor, today the market offers a wide range of modern ECG devices and services supported by the latest developments in ICT. This chapter is devoted to the current state-of-the-art from the area of ECG with a reduced number of leads. We focus on ECG wireless body sensors, differentiating between those that measure only heart rate and are used just for entertainment or during sport activities, and those that actually measure and analyze the ECG signal, with all its waveforms. The latter are elaborated in more detail, particularly our differential ECG sensor and its commercial version Savvy, for which we provide also a comprehensive comparison to other state-of-the-art sensors in that field. It is, however, inevitable that the state-of-the art will change in the future. The constant progress in ICT will always drive the development of new and improved ECG devices. 

  • 36.
    Trobec, R.
    et al.
    Jožef Stefan Institute, Ljubljana, Slovenia.
    Tomasic, Ivan
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Rashkovska, A.
    Jožef Stefan Institute, Ljubljana, Slovenia.
    Depolli, M.
    Jožef Stefan Institute, Ljubljana, Slovenia.
    Avbelj, V.
    Jožef Stefan Institute, Ljubljana, Slovenia.
    ECG pilot studies2018In: SpringerBriefs in Applied Sciences and Technology, Springer Verlag , 2018, no 9783319593388, p. 61-75Chapter in book (Refereed)
    Abstract [en]

    The use of wireless ECG body sensors in two pilot studies is presented. The first study, running at the Department of Cardiovascular Surgery of the University Medical Centre Ljubljana, is focused on the investigation of postoperative atrial fibrillation. The patients are monitored with wireless ECG body sensors one day before and five days after the surgery. The second study has been established at the primary care level in the Community Health Centre Ljubljana, with the intention to establish heart rhythm screening. As both studies are still in progress, we present just their setup and some interesting findings that emerged in their starting phase. Based on evidences from long-term ECG measurements, we identify several still open ECG research questions that could utilize the vast amount of long ECG recordings obtained from the pilot studies. 

  • 37.
    Trobec, R.
    et al.
    Jožef Stefan Institute, Ljubljana, Slovenia.
    Tomasic, Ivan
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Rashkovska, A.
    Jožef Stefan Institute, Ljubljana, Slovenia.
    Depolli, M.
    Jožef Stefan Institute, Ljubljana, Slovenia.
    Avbelj, V.
    Jožef Stefan Institute, Ljubljana, Slovenia.
    Final remarks and conclusions2018In: SpringerBriefs in Applied Sciences and Technology, Springer Verlag , 2018, no 9783319593388, p. 115-119Chapter in book (Refereed)
    Abstract [en]

    The content of our book, devoted to body sensors and their implications to electrocardiography, is recapitulated with this chapter. The identified challenges in long-term ECG data analytics are discussed. Based on the presented material, the near future of mHealth perspectives is foreseen regarding the technology, the usability, and the potential of increased users’ awareness for their own health. 

  • 38.
    Trobec, R.
    et al.
    Jožef Stefan Institute, Ljubljana, Slovenia.
    Tomasic, Ivan
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Rashkovska, A.
    Jožef Stefan Institute, Ljubljana, Slovenia.
    Depolli, M.
    Jožef Stefan Institute, Ljubljana, Slovenia.
    Avbelj, V.
    Jožef Stefan Institute, Ljubljana, Slovenia.
    From multichannel ECG to wireless body sensors2018In: SpringerBriefs in Applied Sciences and Technology, Springer Verlag , 2018, no 9783319593388, p. 13-35Chapter in book (Refereed)
    Abstract [en]

    A more detailed description of multichannel electrocardiography and the differential lead aims to clarify why the multichannel ECG opens a path towards implementation of wireless wearable sensors. Several ways of how the differential lead could be used for heart rhythm monitoring are shown with options for analysis and interpretation of sensor ECG measurements. Finally, the most important vital signs that could be provided by a multifunctional body sensor are presented.

  • 39.
    Trobec, R.
    et al.
    Jožef Stefan Institute, Ljubljana, Slovenia.
    Tomasic, Ivan
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Rashkovska, A.
    Jožef Stefan Institute, Ljubljana, Slovenia.
    Depolli, M.
    Jožef Stefan Institute, Ljubljana, Slovenia.
    Avbelj, V.
    Jožef Stefan Institute, Ljubljana, Slovenia.
    Introduction2018In: Springer Briefs in Applied Sciences and Technology, Springer Verlag , 2018, no 9783319593388, p. 1-12Chapter in book (Other academic)
    Abstract [en]

    The motivation and goals for the development of mobile health solutions are presented. Short history and background of the electrocardiography provide basic principles and facts related to the heart activity and elucidate the path from the measurement of conventional electrocardiogram to the monitoring of the heart by wireless body sensors. A bipolar differential lead is introduced, which has enabled the implementation of a small body sensor for capturing electric potential differences on the skin. The chapter concludes with guidelines on how to read this book and with a short overview of all book chapters.

  • 40.
    Trobec, R.
    et al.
    Joef Stefan Institute, Ljubljana, Slovenia.
    Tomasic, Ivan
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Rashkovska, A.
    Joef Stefan Institute, Ljubljana, Slovenia.
    Depolli, M.
    Joef Stefan Institute, Ljubljana, Slovenia.
    Avbelj, V.
    Joef Stefan Institute, Ljubljana, Slovenia.
    Software for an mHealth system2018In: SpringerBriefs in Applied Sciences and Technology, Springer Verlag , 2018, no 9783319593388, p. 37-59Chapter in book (Refereed)
    Abstract [en]

    A description of software requirements for an mHealth system is provided. Several layers of software are required for proper system functioning: ECG body sensor firmware, applications on smartphones, Cloud applications, and stand-alone applications for personal computers. The main functionality requirements of the mHealth software are described. Additionally, approaches for fulfilling those requirements are proposed.

  • 41.
    Trobec, Roman
    et al.
    Jozef Stefan Inst, Jamova Cesta 39, Ljubljana 1000, Slovenia..
    Avbelj, Viktor
    Jozef Stefan Inst, Jamova Cesta 39, Ljubljana 1000, Slovenia..
    Stanic, Uros
    BRIS, Puhova Ul 10, Ljubljana 1000, Slovenia..
    Depolli, Matjaz
    Jozef Stefan Inst, Jamova Cesta 39, Ljubljana 1000, Slovenia..
    Rashkovska, Aleksandra
    Jozef Stefan Inst, Jamova Cesta 39, Ljubljana 1000, Slovenia..
    Tomasic, Ivan
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Kristofelc, Tomaz
    Jozef Stefan Inst, Jamova Cesta 39, Ljubljana 1000, Slovenia..
    Bregar, Klemen
    Jozef Stefan Inst, Jamova Cesta 39, Ljubljana 1000, Slovenia..
    Kosec, Gregor
    Jozef Stefan Inst, Jamova Cesta 39, Ljubljana 1000, Slovenia..
    System for Mobile Monitoring of Vital Functions and Environmental Context2017In: BIOSENSORS 2016 / [ed] Turner, A Tang, A, ELSEVIER SCIENCE BV , 2017, p. 157-158Conference paper (Refereed)
    Abstract [en]

    The use of ICT in the health care system is aimed to increase efficacy and decrease costs. We have designed a system and services for mobile monitoring of vital physiological parameters and environmental context. The system is based on a small multi-functional wireless body sensor for simultaneous measurement of ECG, temperature, heart rate, respiration rate, and movement. The sensor is wirelessly connected through Bluetooth Smart to a Smartphone. When necessary, the measurements are transferred to a server and can be accessed by authorized personnel. The contribution of the system to improved quality and efficiency of medical care is validated and estimated through several pilot studies.

  • 42.
    Trobec, Roman
    et al.
    Jožef Stefan Institute, Ljubljana, Slovenia.
    Tomasic, Ivan
    Jožef Stefan Institute, Ljubljana, Slovenia.
    Synthesis of the 12-lead electrocardiogram from differential leads2011In: IEEE transactions on information technology in biomedicine, ISSN 1089-7771, E-ISSN 1558-0032, Vol. 15, no 4, p. 615-621Article in journal (Refereed)
    Abstract [en]

    A new approach is proposed for synthesizing the standard 12-lead ECG from three differential leads formed by pairs of proximal electrodes on the body surface. The method is supported by a statistical analysis that gives the best personalized positions of electrodes. The measurements from multichannel ECGs were used to calculate the differential leads. Our algorithm searches for optimal differential leads and the corresponding personalized transformation matrix that is used to synthesize the standard 12-lead ECG. The algorithm has been evaluated on 99 multichannel ECGs measured on 30 healthy subjects and 35 patients scheduled for elective cardiac surgery. It is shown that the algorithm significantly outperforms the synthesis based on the EASI lead system with medians of correlation coefficients greater than 0.954 for all 12 standard leads. To determine the optimal number of differential leads, the syntheses for two, three, and four differential leads were calculated. The analysis shows that 3 is the optimal number of differential leads for practical applications. Because of the proximity of the differential electrodes, the proposed approach offers an opportunity for the synthesis of a standard 12-lead ECG with wireless electrodes.

  • 43.
    Trobec, Roman
    et al.
    Jožef Stefan Institute, Ljubljana, Slovenia.
    Tomasic, Ivan
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Rashkovska, Aleksandra
    Jožef Stefan Institute, Ljubljana, Slovenia.
    Depolli, Matjaž
    Jožef Stefan Institute, Ljubljana, Slovenia.
    Avbelj, Viktor
    Jožef Stefan Institute, Ljubljana, Slovenia.
    Body Sensors and Electrocardiography2017Book (Other academic)
1 - 43 of 43
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