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  • 101.
    Antonsson, Ann-Beth
    et al.
    KTH, School of Technology and Health (STH), Ergonomics (Closed 20130701).
    Christensson, Bengt
    KTH. IVL Svenska Miljöinstitutet.
    Berge, Johan
    Rättsmedicinalverket.
    Sjögren, Bengt
    Karolinska Institutet.
    Fatal Carbon Monoxide Intoxication After AcetyleneGas Welding of Pipes2013In: Annals of Occupational Hygiene, ISSN 0003-4878, E-ISSN 1475-3162, Vol. 57, no 5, p. 662-666Article in journal (Refereed)
    Abstract [en]

    Acetylene gas welding of district heating pipes can result in exposure to high concentrations of carbon monoxide. A fatal case due to intoxication is described. Measurements of carbon monoxide revealed high levels when gas welding a pipe with closed ends. This fatality and these measurements highlight a new hazard, which must be promptly prevented.

  • 102.
    Antonsson Lundberg, Ann-Beth
    KTH, School of Technology and Health (STH), Ergonomics.
    A systems analysis of a target group of enterprises: A new way forward for the dissemination of research results and sustainable technologies2006Conference paper (Other academic)
  • 103.
    Antonsson Lundberg, Ann-Beth
    KTH, School of Technology and Health (STH), Ergonomics.
    An interactive Internet tool supporting risk management in SMEs: The Chemical Guide (KemiGuiden)2005Conference paper (Other academic)
  • 104.
    Antonsson Lundberg, Ann-Beth
    KTH, School of Technology and Health (STH), Health Systems Engineering, Ergonomics. IVL Svenska Miljöinstitutet AB.
    Företagshälsovård2014In: Människan i arbetslivet: Teori och praktik / [ed] Eva Holmström, Kerstina Olsson, Lund: Studentlitteratur AB , 2014, 2:1, p. 199-223Chapter in book (Refereed)
  • 105.
    Antonsson Lundberg, Ann-Beth
    KTH, School of Technology and Health (STH), Ergonomics.
    Improving work environment in small enterprises: The need for a holistic perspective and adaptation to small enterprise reality2007Conference paper (Other academic)
  • 106.
    Antonsson Lundberg, Ann-Beth
    KTH, School of Technology and Health (STH), Ergonomics.
    Interviews with employees reporting work-related injuries as the basis for intervention2011Conference paper (Refereed)
  • 107.
    Antonsson Lundberg, Ann-Beth
    KTH, School of Technology and Health (STH), Ergonomics.
    Kapitel 1.: Varför företagshälsovård?2011In: Framgångsrik företagshälsovård: Möjligheter och metoder, Stockholm: Norstedts Juridik AB, 2011Chapter in book (Other (popular science, discussion, etc.))
    Abstract [en]

    Företagshälsovård, fhv, är en viktig aktör i välfärdssamhället. Den ska bidra både till att förebygga ohälsa och främja hälsa samt till att ska pagoda och säkra arbetsplatser där de anställda inte riskerar att skadas eller bli sjuka. Omvärldens förväntningar är höga. För att uppfylla dem krävs att fhv har en bred kompetens och att arbetet bygger på samarbete både mellan olika kompetenser inom den egna verksamheten och med de företag och organisationer som fhv arbetar för.

  • 108.
    Antonsson Lundberg, Ann-Beth
    KTH, School of Technology and Health (STH), Ergonomics.
    Kapitel 4: Att förstå kunden2011In: Framgångsrik företagshälsovård: Möjligheter och metoder, Stockholm: Norstedts Juridik AB, 2011Chapter in book (Other (popular science, discussion, etc.))
    Abstract [en]

    Verksamhet, ekonomiska förutsättningar, drivkrafter och värderingar varierar för FHV:s kunder. För att lyckas i arbetet med att stödja kunden, behöver FHV förstå hur dessa faktorer påverkar arbetsmiljöarbetet och hur insatser bäst anpassas till varje kund.

  • 109.
    Antonsson Lundberg, Ann-Beth
    KTH, School of Technology and Health (STH), Ergonomics.
    Kapitel 9: Företagshälsovård och småföretag2011In: Framgångsrik företagshälsovård: Möjligheter och metoder, Stockholm: Norstedts Juridik AB, 2011Chapter in book (Other (popular science, discussion, etc.))
    Abstract [en]

    Många företag med mindre än 50 anställda har någon form av avtal med FHV och de flesta är nöjda. Deras anställda står dock bara för en liten andel av alla arbetstagare som har tillgång till fhv. En stor del av småföretagen utnyttjar inte FHV:s breda kompetens utan anlitar dem främst för hälsoundersökningar. Det betyder att det finns en stor utvecklingspotential om man kan få de mindre företagen att efterfråga fler tjänster.

  • 110.
    Antonsson Lundberg, Ann-Beth
    KTH, School of Technology and Health (STH), Ergonomics.
    Procurement demands: a management strategy for sustainability2011Conference paper (Refereed)
  • 111.
    Antonsson Lundberg, Ann-Beth
    KTH, School of Technology and Health (STH), Ergonomics.
    Risk assessment tools for small enterprises: evaluation of uptake and effect2009In: USE 2009: Programme and abstract book, 2009, p. 118-118Conference paper (Other academic)
    Abstract [en]

    Background: Risk assessment is a core component in the management of the working environment. Risk assessment helps identify and prioritize risks and reduce risks through implementation of control measures. Aim: To evaluate how tools for risk assessment are used by small enterprises and what the result is from using the tools. Method: Randomly selected small enterprises in printing and electroplating industry were contacted and asked to participate in an evaluation of tools for chemical risk assessment developed to suit small enterprises. An initial interview was made with the enterprises accepting to participate in the testing, aiming at surveying how they use to assess chemical risks. The enterprises were provided with one out of six tools. Ten enterprises in each sector were asked to test each tool, adding up to 20 enterprises testing each tool. After three and six months the enterprise was contacted. If they had tested the tool, a new interview was made, exploring their opinion on the tool and their experiences from using it. Enterprises not having tested the tools were also interviewed about the reasons why they did not use the tool they were provided. In enterprises having used the tools, an expert risk assessment was made and compared to the risk assessment of the enterprise in order to evaluate the quality of the risk assessment tool and the enterprise's use of it. Result: More than 60 % of the enterprises accepted to test the tools, reflecting an interest and concern for chemical risks in their work environment. The follow-up interviews are currently conducted and will be finished during April 2009. The results show how risk assessment works in practice in small enterprises. The study has revealed several problems with different tools and some unexpected results. One example is that several enterprises have concluded that they are content with their old method for risk assessment, which was using safety data sheets, reflecting a profound lack of understanding of what risk assessment is about. Results from the evaluation will be presented, showing how small enterprises perceive the different kinds of tools tested and what the outcomes in terms of quality are of the tested tools. The results will be discussed in relation to the enterprises and their previous experience of and knowledge about risk assessment.

  • 112.
    Antonsson Lundberg, Ann-Beth
    KTH, School of Technology and Health (STH), Ergonomics.
    Risk management in small enterprises: A system analysis of what works and what doesn´t2006Conference paper (Other academic)
  • 113.
    Antonsson Lundberg, Ann-Beth
    KTH, School of Technology and Health (STH), Ergonomics.
    Studiehandledning2011In: Framgångsrik företagshälsovård: Möjligheter och metoder, Stockholm: Norstedts Juridik AB, 2011Chapter in book (Other (popular science, discussion, etc.))
  • 114.
    Antonsson Lundberg, Ann-Beth
    et al.
    KTH, School of Technology and Health (STH), Health Systems Engineering, Ergonomics. IVL Svenska Miljöinstitutet AB.
    Hasle, Peter
    Aalborg Universitet.
    How can the context affect what strategies are effective in improving the working environment in small companies?2015Conference paper (Other academic)
  • 115.
    Antonsson Lundberg, Ann-Beth
    et al.
    KTH, School of Technology and Health (STH), Health Systems Engineering, Ergonomics. IVL Svenska Miljöinstitutet AB.
    Hasle, Peter
    Aalborg Universitet.
    What kind of knowledge do small companies need to improve their working environment?2015Conference paper (Other academic)
  • 116.
    Antonsson Lundberg, Ann-Beth
    et al.
    KTH, School of Technology and Health (STH), Ergonomics.
    Holmefalk, C
    Hägg, GM
    Kumar, R
    Scmidt, L
    Hur förbättra städares arbetsförhållanden?2007In: NES2007 / [ed] Cecilia Berlin, Lars-Ola Bligård, 2007Conference paper (Other academic)
  • 117.
    Antonsson Lundberg, Ann-Beth
    et al.
    KTH, School of Technology and Health (STH), Ergonomics.
    Nyman, Teresia
    KI, Institutionen för folkhälsovetenskap.
    Education for Occupational health service professionals in different countries2011Conference paper (Other academic)
  • 118.
    Antonsson Lundberg, Ann-Beth
    et al.
    KTH, School of Technology and Health (STH), Ergonomics.
    Schmidt, L
    Swedish Occupational Health Services and Small Enterprises: How does it work?2005In: OHS2005 Conference Proceedings: SJWEH Supplements 2005; no 1, 2005Conference paper (Other academic)
  • 119.
    Antonsson Lundberg, Ann-Beth
    et al.
    KTH, School of Technology and Health (STH), Ergonomics.
    Verschoor, Atie H
    Ild care foundation, Maastricht.
    General Purpose of WE-LCA2004In: Working Environment in Life-Cycle Assessment / [ed] Poulsen, Jensen, Antonsson, Bengtsson, Karling, Schmidt, Brekke, Becker, Verschoor, Society of Environmental Toxicology and Chemistry (SETAC), 2004Chapter in book (Other (popular science, discussion, etc.))
  • 120.
    Aodah, Anwar
    et al.
    KTH, School of Technology and Health (STH), Data- och elektroteknik.
    Öcüt, Bora
    KTH, School of Technology and Health (STH), Data- och elektroteknik.
    Agilt regressionssystemtest2012Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Detta examensarbete utfördes på avdelningsnivån CCS på avdelningen PDU Platforms på Ericsson. Avdelningen ville förändra sin nuvarande arbetsprocess genom att övergå från Daily Build, att bygga och testa en gång om dagen, till ett mer kontinuerligt byggande och testande. CCS hanterar och tillhandahåller kontrollsystemtjänster för RNC applikationer och äldre RBS.

     

    Målet med detta examensarbete var att automatisera testprocesser för att kunna utföra kontinuerliga tester. Första steget i arbetet var att ta fram ett specifikt användningsfall, ett use case, att arbeta mot. Detta skedde genom analys av felrapporter och detta ledde till att nodomstarter definierades som ett första användningsfall. När användningsfallet var definierat, skedde analys av plattform att använda för automatisering, samt vilka steg som behövde automatiseras. De var enligt följande, uppladdning med ftp, exekvering av filer med Telnet och nodkonfiguration med verktyget Cicc.

  • 121.
    Araya, Cristian
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Singh, Manjinder
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Web API protocol and security analysis2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    There is problem that every company has its own customer portal. This problem can be solved by creating a platform that gathers all customers’ portals in one place. For such platform, it is required a web API protocol that is fast, secure and has capacity for many users. Consequently, a survey of various web API protocols has been made by testing their performance and security.

    The task was to find out which web API protocol offered high security as well as high performance in terms of response time both at low and high load. This included an investigation of previous work to find out if certain protocols could be ruled out. During the work, the platform’s backend was also developed, which needed to implement chosen web API protocols that would later be tested. The performed tests measured the APIs’ connection time and their response time with and without load. The results were analyzed and showed that the protocols had both pros and cons. Finally, a protocol was chosen that was suitable for the platform because it offered high security and fast connection. In addition, the server was not affected negatively by the number of connections. Reactive REST was the web API protocol chosen for this platform.

  • 122. Arman, Rebecka
    et al.
    Wikström, Ewa
    Tengelin, Ellinor
    Dellve, Lotta
    KTH, School of Technology and Health (STH), Health Systems Engineering, Ergonomics.
    Work activities and stress among managers in health care2012In: The Work of Managers: Towards a Practice Theory of Management / [ed] Tengblad, Sten, Oxford: Oxford University Press, 2012, 1Chapter in book (Other academic)
    Abstract [en]

    This chapter reports on the work activities, time-use patterns, and stress patterns of ten health care managers in Sweden. The qualitative and quantitative evidence reveals the fragmentation in their nine-hour working days where each activity, on average, lasts only ten minutes. The time-use patterns vary individually though some patterns are related to position and unit type. Activities deal with the coexisting and competing logics of employeeship, administration, and strategy and risk handling. None of the managers’ approaches for handling the multiple legitimation processes and delimiting their workload boundaries really challenges the complexity of the coexistence of the multiple logics or the boundlessness of their working hours. Using biophysical measures, the research finds that stress reported by the managers is caused by (a) interruptions during challenging tasks and (b) personal situations such as private dilemmas and conflict-loaded or ineffective meetings. It is important to acknowledge managers’ fragmented working situation and to recognize that management should be seen as collective process, or as part of an administrative system.

  • 123.
    Aronson, Eran
    KTH, School of Technology and Health (STH), Design, Work Environment, Safety and Health, DASH.
    Research Project: Lighting Häggvik Tunnel, Sollentuna2013Report (Other academic)
    Abstract [en]

    A reserch paper investigating the posibility of lowering light levels in tunnel while using LED's. Done with and for Trafikverket as part of an ongoing research regarding tunnel lighting.

  • 124.
    Aronson, Eran
    KTH, School of Technology and Health (STH).
    Visual adaptation for tunnel entrance2013Report (Other academic)
    Abstract [en]

    A research report done by the lighting laboratory at KTH STH for Trafikverket. The report is presenting a second stage of tunnel lighting research, focusing on the tunnel entrance zone, where improvements to existing recommendations are suggested.

  • 125. Aronsson, Gunnar
    et al.
    Eklund, Jörgen
    KTH, School of Technology and Health (STH), Ergonomics.
    Randle, Hanne
    Svensson, Lennart
    Inte bara här och nu utan också där och då: Reflektioner om arbetslivsforskningen och det stora hållbarhetsprojektet2009In: Arbetslivsforskning och hållbarhet: Arbetsliv i omvandling / [ed] I: Porsfelt, Växjö: Växjö universitet , 2009, 1Chapter in book (Other academic)
  • 126.
    Aronsson, K
    et al.
    Karolinska Institutet.
    Teär Fahnehjelm, K
    Karolinska Institutet.
    Nylén, P
    KTH, School of Technology and Health (STH), Ergonomics.
    Eklund, Jörgen
    KTH, School of Technology and Health (STH), Ergonomics.
    Synergonomi och ögonbesvär hos personal på ögonsjukhus.2012Conference paper (Other academic)
    Abstract [sv]

    Ögonläkare, ögonsjuksköterskor, optiker och annan personal på ögonsjukhus arbetar ofta med synkrävande arbetsuppgifter i dämpad belysning eller helt utan allmänbelysning. Inför den planerade byggnationen av ett nytt ögonsjukhus i Stockholm ca år 2018 gjordes en enkätstudie för att kartlägga ögonbesvär och trötthet hos personalen på S:t Eriks Ögonsjukhus. Studien som är ett multidisciplinärt samarbetsprojekt mellan S:t Erik, Karolinska Institutet och Kungliga Tekniska Högskolan, syftar till att optimera belysning, dagsljusinsläpp och ljusmiljö vid det nya ögonsjukhuset.

    Totalt 265 anställda på S:t Eriks Ögonsjukhus samt 60 röntgenläkare och 45 barnläkare, varav de senare två  utgjorde jämförelsegrupper, inviterades till  studien.  Enkäten som distribuerades baserades på synergonomienkäter av Knave och Hemphälä och bestod av 31 validerade frågor om subjektiva ögonbesvär, nuvarande belysning, tillgång till dagsljus och välbefinnande. Ögonbesvären räknades om till ett gruppmedelvärde (ögonbesvärsindex) med avseende på svårighetsgrad och frekvens. Studien är godkänd av Etikprövningsnämnden. 

    Nittiosex av 265 (33%) anställda på S:t Eriks Ögonsjukhus hade t o m juni 2012 besvarat enkäten tillsammans med 23 röntgenläkare (38%) och 14 barnläkare (31%). Ögonbesvär som torrhets- och gruskänsla var vanligt förekommande hos alla yrkesgrupper på ögonsjukhuset och generellt vanligare hos kvinnor. Då samtliga grupper jämfördes med avseende på ögonbesvärsindex var skillnaden mellan män och kvinnor statistiskt säkerställd (p<0,05). Röntgenläkarna rapporterade högst ögonbesvärsindex och barnläkarna lägst, skillnaden mellan dessa yrkesgrupper var signifikant (p<0,05). Ögonpersonal och röntgenläkare som rapporterade att de ofta arbetade i mörker, associerade detta med  ökad trötthet i högre grad än  med barnläkarna (p<0,05).

    Ögonbesvär var vanliga hos ögonpersonalen inkluderade i studien. Den grupp som arbetade mest i mörker hade mer ögonbesvär än den grupp som arbetade minst i mörker. Kvinnor hade mer ögonbesvär än män. Arbete i mörker ökade den subjektiva känslan av trötthet . Optimala ljusförhållanden och bra synergonomi bör ges hög prioritet vid planering av ett nytt ögonsjukhus.

  • 127.
    Aronsson, K
    et al.
    Karolinska Institutet.
    Teär Fahnhjelm, K
    Karolinska Institutet.
    Nylén, P
    KTH, School of Technology and Health (STH), Ergonomics.
    Eklund, Jörgen
    KTH, School of Technology and Health (STH), Ergonomics.
    Visual ergonomics and eye strain in eye careprofessionals2012In: NES2012 Proceedings: Ergonomics for sustainability and growth / [ed] Ann-Beth Antonsson, Göran M Hägg, 2012Conference paper (Other academic)
    Abstract [en]

    Eye care professionals spend many hours a day in darkness performing visually demanding tasks. A new eye hospital will be built in Stockholm 2018. The current lighting, logistics, and working conditions are analysed in a multidisciplinary project aiming to optimise settings in the new hospital. The main purpose of the present project was to study visual ergonomics and current eye strain in employees at an eye hospital. Ninety-six employees answered a validated questionnaire regarding their experiences of light, visual ergonomics and eye strain problems. Twenty-three radiologists and 14 paediatricians at a university hospital were used as comparison groups. Eye strain was common in all departments at the hospital but was significantly more common only among radiologists compared to paediatricians. Overall, women experienced significantly more eye strain than men.

  • 128.
    Arrospide Echegaray, Daniel
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Utvärdering av Självstyrandes-utvecklarramverket2016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Within software engineering there is a diversity of process methods where each one has its specific purpose. A process method can be described as being a repeatable set of step with the purpose to achieve a task and reach a specific result. The majority of process methods found in this study are focused on the software product being developed. There seems to be a lack of process methods that can be used by software developers for there individual soft- ware process improvement. Individual software process improvement, refers to how the in- dividual software developer chooses to structure their own work with the purpose to obtain a specific result

    The Self-Governance Developer Framework (also called SGD-framework) whilst writing this is a newly developed process framework with the purpose of aiding the individual soft- ware developer to improve his own individual software process. Briefly explained the framework is intended to contain all the activities that can come up in a software project. The problem is that this tool has not yet been evaluated and therefore it is unknown if it is relevant for its purpose. To frame and guide the study three problem questions has been for- mulated (1) Is the framework complete for a smaller company in regards to it activities? (2) How high is the cost for the SGD-framework in regard of time?

    The goal of the study is to contribute for future studies for the framework by performing an action study where the Self-Governance Developer Framework is evaluated against a set of chosen evaluation criteria.

    An inductive qualitative research method was used when conducting the study. An induc- tive method means that conclusions are derived from empirically gathered data and from that data form general theories. Specifically, the action study method was used. Data was gathered by keeping a logbook and also time logging during the action study. To evaluate the framework, some evaluation criteria was used which were (1) Completeness, (2) Se- mantic correctness, (3) Cost. A narrative analysis was conducted over the data that was gathered for the criteria. The analysis took the problem formulations in regard.

    The results from the evaluation showed that the framework was not complete with the re- gards of the activities. Although next to complete as only a few activities were further needed during the action study. A total of 3 extra activities were added over the regular 40 activities. Around 10% of the time spent in activities were in activities outside of the Self- Governance Developer Framework. The activities were considered to finely comminute for the context of a smaller company. The framework was considered highly relevant for im- proving the individual software developers own process. The introduction cost in this study reflect on the time it took until the usage of the framework was considered consistent. In this study it was approximately 24 working days with a usage about 3.54% of an eight-hour work day. The total application cost of usage of the framework in the performed action study was on average 4.143 SEK/hour or 662,88 SEK/month. The template cost used was on 172.625 SEK/hour. 

  • 129.
    Arroyo Porras, Igor Alfredo
    KTH, School of Technology and Health (STH).
    Developing an sleep scorer by using Biosignals in Matlab.: Evaluation for sleep apnea patients.2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Nowadays, sleep disorders e.g. sleep apnea —the cessation of airflow at the nose and mouth lasting at least 10 second— are a broadly problem around the world. Direct and indirect costs associated to sleep problems are outsize and the quality of patient life is deteriorated because of it. In addition, Sleep is a fundamental part of everyday life, the lack of it or the poor quality of sleep may lead into the development of important diseases. Sleep studies are usually carried out by specialists by means of polysomnography. Polysomnography is a type of sleep study which is consisting of EEG, EOG, EMG, ECG, respiratory signals and/or many other biosignals which together can be used to determine the state of patient’s sleep and any other issue. Nowadays, visual inspection of these signals forms the “gold standard” in sleep clinics. The cost of monitoring a person overnight, the scarcity of beds available and the uncertainty of whether the results are representative of a normal nights’ sleep means that a move to home diagnostics is likely to be advantageous. Therefore, a necessity for home recorders systems capable of perform this kind of analysis has come out. A state machine based automatic scorer is developed and evaluated in Matlab by using 12 recordings of apnoeic patients from sleep heart health study (SHHS) database. By the analysis of EEG, EOG, EMG, Oxygen saturation (Sao2) and respiratory movements signals, the implemented algorithm is trained and evaluated to detect the five stages of subject’s sleep (Wake, N1, N2, N3, or REM) as well as apnoeic episodes according to guidelines from American Academy of Sleep Medicine (AASM). In the final evaluation of algorithms, the automatic scorer achieved 74±5.27% accuracy for all five stages and Cohen’s kappa of 0.5 for the overall set of 12 patients, being the accuracy better for healthier subjects and reaching in this case 78±4.05%. The analysis of the sleep apnea concluded with a sensitivity of 47.08%, a specificity of 83.38%, and an accuracy of 78.1%. Differences in the performance among patients according to their apnea/hypopnea index were significant.

     

    Key Words: Polysomnography, AASM, Sleep apnea/hypopnea.

  • 130. Arvedsen, SK
    et al.
    Eiken, Ola
    KTH, School of Technology and Health (STH), Basic Science and Biomedicine, Environmental Physiology. KTH, School of Technology and Health (STH), Centres, Swedish Aerospace Physiology Centre, SAPC.
    Kölegård, Roger
    KTH, School of Technology and Health (STH), Basic Science and Biomedicine, Environmental Physiology. KTH, School of Technology and Health (STH), Centres, Swedish Aerospace Physiology Centre, SAPC.
    Petersen, L. G.
    Damgaard, M.
    Body height and arterial pressure in seated and supine young males during +2 G centrifugation2015In: American Journal of Physiology. Regulatory Integrative and Comparative Physiology, ISSN 0363-6119, E-ISSN 1522-1490, Vol. 309, no 9Article in journal (Refereed)
    Abstract [en]

    It is known that arterial pressure correlates positively with body height in males and it has been suggested that this is due to the increasing vertical hydrostatic gradient from the heart to the carotid baroreceptors. Therefore we tested the hypothesis that a higher gravitoinertial stress induced by the use of a human centrifuge would increase mean arterial pressure (MAP) more in tall than in short males in the seated position. In short (162-171cm, n=8) and tall (194-203cm, n=10) healthy males (18-41y), brachial arterial pressure, heart rate (HR) and cardiac output were measured during +2G centrifugation, while they were seated upright with the legs kept horizontal (+2Gz). In a separate experiment, the same measurements were done with the subjects supine (+2Gx). During +2Gz MAP increased in the short (22±2 mmHg, p<0.0001) and tall (23±2 mmHg, p<0.0001) males, with no significant difference between the groups. HR increased more (p<0.05) in the tall than in the short group (14±2 versus 7±2 bpm). Stroke volume (SV) decreased in the short group (26±4 mL, p=0.001) and more so in the tall group (39±5 mL, p<0.0001; short vs tall p=0.047). During +2GX, systolic arterial pressure increased (p<0.001) and SV (p=0.012) decreased in the tall group only. In conclusion, during +2Gz MAP increased in both short and tall males with no difference between the groups. However, in the tall group HR increased more during +2Gz which could be caused by a larger hydrostatic pressure gradient from heart to head leading to greater inhibition of the carotid baroreceptors.

  • 131.
    Ashfaq, Awais
    KTH, School of Technology and Health (STH).
    Segmentation of Cone Beam CT in Stereotactic Radiosurgery2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    C-arm Cone Beam CT (CBCT) systems – due to compact size, flexible geometry and low radiation exposure – inaugurated the era of on-board 3D image guidance in therapeutic and surgical procedures. Leksell Gamma Knife Icon by Elekta introduced an integrated CBCT system to determine patient position prior to surgical session, thus advancing to a paradigm shift in facilitating frameless stereotactic radiosurgeries. While CBCT offers a quick imaging facility with high spatial accuracy, the quantitative values tend to be distorted due to various physics based artifacts such as scatter, beam hardening and cone beam effect. Several 3D reconstruction algorithms targeting these artifacts involve an accurate and fast segmentation of craniofacial CBCT images into air, tissue and bone.

    The objective of the thesis is to investigate the performance of deep learning based convolutional neural networks (CNN) in relation to conventional image processing and machine learning algorithms in segmenting CBCT images. CBCT data for training and testing procedures was provided by Elekta. A framework of segmentation algorithms including multilevel automatic thresholding, fuzzy clustering, multilayer perceptron and CNN is developed and tested against pre-defined evaluation metrics carrying pixel-wise prediction accuracy, statistical tests and execution times among others. CNN has proven its ability to outperform other segmentation algorithms throughout the evaluation metrics except for execution times. Mean segmentation error for CNN is found to be 0.4% with a standard deviation of 0.07%, followed by fuzzy clustering with mean segmentation error of 0.8% and a standard deviation of 0.12%. CNN based segmentation takes 500s compared to multilevel thresholding which requires ~1s on similar sized CBCT image.

    The present work demonstrates the ability of CNN in handling artifacts and noise in CBCT images and maintaining a high semantic segmentation performance. However, further efforts targeting CNN execution speed are required to utilize the segmentation framework within real-time 3D reconstruction algorithms.

  • 132.
    Askfors, Ylva
    et al.
    KTH, School of Technology and Health (STH), Centres, Centre for Technology in Medicine and Health, CTMH.
    Hollmark, Malin
    KTH, School of Technology and Health (STH), Centres, Centre for Technology in Medicine and Health, CTMH.
    Haasl, Sjoerd
    KTH, School of Technology and Health (STH), Centres, Centre for Technology in Medicine and Health, CTMH.
    Guve, Bertil
    KTH, School of Technology and Health (STH), Centres, Centre for Technology in Medicine and Health, CTMH.
    Learning In Interdisciplinary Networks - For An Efficient Innovation System And An Improved Healthcare2013In: ICERI 2013: conference proceedings, International Association of Technology, Education and Development, IATED , 2013, p. 1000-1007Conference paper (Refereed)
    Abstract [en]

    Clinical Innovation Fellowships is a program that creates conditions for learning and for innovative thought to take place. It aims to educate innovators and to develop innovations that result in more efficient healthcare production. [1] Multiprofessional 4-person-teams of fellow candidates with competence in engineering, medicine, industrial design and management work together full time for eight months, with the aim to identify clinical needs that can be met by a medical technology innovation (process, product or service) or by an organizational improvement. Early in the program, the team spends two months full time at a clinical department observing the various healthcare activities. Among the clinical needs identified by the fellow candidates three needs will be chosen, validated and approved by the department's management as appropriate starting points for student thesis projects. We describe the phenomenon we have seen when introducing new disciplines as observers and problem solvers in a healthcare context as the improbable dialogue. The improbable dialogue is the unexpected dialogue between professionals and students, or professionals within separate disciplinary boundaries that generally never meet professionally. Such a dialogue may however be the channel in which the curiosity and openness of a novice can reflect on the daily work of a specialist, ultimately resulting in the development of ideas, knowledge exchange and learning. The Clinical Innovation Fellowships program enables this learning to take place and has shown to be a successful catalyst for the improbable dialogue; the unexpected, interdisciplinary, dialogue between healthcare specialists, high qualified fellow candidates with working experience and thesis students from different educational fields. This paper gives a qualitative problematization of the program with respect to the strategy and method of including thesis students to reinforce (almost) any innovation system through interdisciplinary, multiprofessional collaboration, where healthcare and academy learn from each other.

  • 133.
    Aslamy, Benjamin
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Utveckling av ett multisensorsystem för falldetekteringsanordningar2016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Accidental falls among the elderly is a major public health problem. As a result, a variety of systems have been developed for remote monitoring of the elderly to permit early detection of falls. The majority of the research that has been done so far in fall accidents has focused on developing new more successful algorithms spe- cifically to identify fall from non-fall. Although the statistics show that mortality and injuries caused by falls are increasing every year in conjunction with the in- creasing proportion of older people in the population.

    This thesis is about improving the current fall detection devices by covering the gaps and meet the needs of the current fall detection techniques. The improve- ments that have been identified is to provide a secure assessment of the patient's health and be able to call for aid more quickly when a fall occurs. Another im- provement is the mobility for the elderly to be outdoors and have the ability to per- form daily activities without being limited by the location position.

    In summary it can be said that a multisensor system in form of a prototype has been designed to cover the deficiencies and improvements that have been identi- fied. Apart from detection of falls and body movements through an accelerometer sensor the prototype does also include a sensor for detecting vital signs in form of ECG. It also supports cellular and wireless network communication in form of GPRS and Wi-Fi to enable freedom of movement for the elderly. Furthermore, the prototype includes a sensor for GPS that provides information about location position. 

  • 134.
    Asplund, Maria
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Conjugated Polymers for Neural Interfaces: Prospects, possibilities and future challenges2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Within the field of neuroprosthetics the possibility to use implanted electrodes for communication with the nervous system is explored. Much effort is put into the material aspects of the electrode implant to increase charge injection capacity, suppress foreign body response and build micro sized electrode arrays allowing close contact with neurons. Conducting polymers, in particular poly(3,4-ethylene dioxythiophene) (PEDOT), have been suggested as materials highly interesting for such neural communication electrodes. The possibility to tailor the material both mechanically and biochemically to suit specific applications, is a substantial benefit with polymers when compared to metals. PEDOT also have hybrid charge transfer properties, including both electronic and ionic conduction, which allow for highly efficient charge injection.

     

    Part of this thesis describes a method of tailoring PEDOT through exchanging the counter ion used in electropolymerisation process. Commonly used surfactants can thereby be excluded and instead, different biomolecules can be incorporated into the polymer. The electrochemical characteristics of the polymer film depend on the ion. PEDOT electropolymerised with heparin was here determined to have the most advantageous properties. In vitro methods were applied to confirm non-cytotoxicity of the formed PEDOT:biomolecular composites. In addition, biocompatibility was affirmed for PEDOT:heparin by evaluation of inflammatory response and neuron density when implanted in rodent cortex.

     

    One advantage with PEDOT often stated, is its high stability compared to other conducting polymers. A battery of tests simulating the biological environment was therefore applied to investigate this stability, and especially the influence of the incorporated heparin. These tests showed that there was a decline in the electroactivity of PEDOT over time. This also applied in phosphate buffered saline at body temperature and in the absence of other stressors. The time course of degradation also differed depending on whether the counter ion was the surfactant polystyrene sulphonate or heparin, with a slightly better stability for the former.

     

    One possibility with PEDOT, often overlooked for biological applications, is the use of its semi conducting properties in order to include logic functions in the implant. This thesis presents the concept of using PEDOT electrochemical transistors to construct textile electrode arrays with in-built multiplexing. Using the electrolyte mediated interaction between adjacent PEDOT coated fibres to switch the polymer coat between conducting and non conducting states, then transistor function can be included in the conducting textile. Analogue circuit simulations based on experimentally found transistor characteristics proved the feasibility of these textile arrays. Developments of better polymer coatings, electrolytes and encapsulation techniques for this technology, were also identified to be essential steps in order to make these devices truly useful.

     

    In summary, this work shows the potential of PEDOT to improve neural interfaces in several ways. Some weaknesses of the polymer and the polymer electronics are presented and this, together with the epidemiological data, should point in the direction for future studies within this field.

  • 135.
    Asplund, Maria
    et al.
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Hamedi, Mahiar
    Forchheimer, Robert
    Inganäs, Olle
    von Holst, Hans
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Wire electronics and woven logic, as a potential technology for neuroelectronic implantsManuscript (Other (popular science, discussion, etc.))
    Abstract [en]

    New strategies to improve neuron coupling to neuroelectronic implants are needed. In particular, to maintain functional coupling between implant and neurons, foreign body response like encapsulation must me minimized. Apart from modifying materials to mitigate encapsulation it has been shown that with extremely thin structures, encapsulation will be less pronounced. We here utilize wire electrochemical transistors (WECTs) using conducting polymer coated fibers. Monofilaments down to 10 μm can be successfully coated and weaved into complex networks with built in logic functions, so called textile logic. Such systems can control signal patterns at a large number of electrode terminals from a few addressing fibres. Not only is fibre size in the range where less encapsulation is expected but textiles are known to make successful implants because of their soft and flexible mechanical properties. Further, textile fabrication provides versatility and even three dimensional networks are possible. Three possible architectures for neuroelectronic systems are discussed. WECTs are sensitive to dehydration and materials for better durability or improved encapsulation is needed for stable performance in biological environments.

  • 136.
    Asplund, Maria
    et al.
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Hamedi, Mahiar
    Inganäs, Olle
    Forchheimer, Robert
    von Holst, Hans
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Neural microcontacts with wire electrodes and woven logic2007Conference paper (Refereed)
  • 137.
    Asplund, Maria
    et al.
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Nilsson, Mats
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Jacobsson, Anders
    von Holst, Hans
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Incidence of traumatic peripheral nerve injuries and amputations in Sweden between 1998 and 20062008In: Neuroepidemiology, ISSN 0251-5350, E-ISSN 1423-0208Article in journal (Refereed)
    Abstract [en]

    Background: To define the epidemiological pattern of nerve injuries and traumatic amputations in Sweden, 1998-2006, and investigate possible targets for emerging neural engineering and neuroprosthetic technologies.

    Methods: The Swedish Hospital Discharge Register was used as basis of information, including data from all public in-patient care, excluding out-patient data. ICD-10 codes were screened for nerve injuries and traumatic amputations of high incidence or in-patient care time. Selected codes, causing factors, age and gender distribution were discussed in detail, and potential targets for tailored solutions were identified.

    Results: Incidence rate was determined to 13.9 for nerve injuries and 5.21 for amputations per 100 000 person-yrs. The majority of injuries occurred at wrist and hand level although it could be concluded that these are often minor injuries requiring less than a week of hospitalization. The single most care consuming nerve injury was brachial plexus injury constituting, in average, 68 injuries and 960 hospital days annually. When minor amputations of fingers and toes were disregarded, most frequent site of amputation was between knee and ankle (24 patients / year).

    Conclusions: Based on analysis of incidence and care time, we find that brachial plexus injuries and lower leg amputations should be primary targets of these new technologies.

  • 138.
    Asplund, Maria
    et al.
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Nyberg, Tobias
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Inganäs, Olle
    Electroactive polymers for neural interfaces2010In: Polymer chemistry, ISSN 1759-9954, Vol. 1, no 9, p. 1374-1391Article, review/survey (Refereed)
    Abstract [en]

    Development of electroactive conjugated polymers, for the purpose of recording and eliciting signals in the neural systems in humans, can be used to fashion the interfaces between the two signalling systems of electronics and neural systems. The design of desirable chemical, mechanical and electrical properties in the electroactive polymer electrodes, and the means of integration of these into biological systems, are here reviewed.

  • 139.
    Asplund, Maria
    et al.
    KTH, School of Technology and Health (STH), Neuronic Engineering (Closed 20130701).
    Thaning, Elin
    KTH, School of Technology and Health (STH), Neuronic Engineering (Closed 20130701).
    Lundberg, J.
    Sandberg-Nordqvist, A. C.
    Kostyszyn, B.
    Inganas, O.
    von Holst, Hans
    KTH, School of Technology and Health (STH), Neuronic Engineering (Closed 20130701).
    Toxicity evaluation of PEDOT/biomolecular composites intended for neural communication electrodes2009Article in journal (Refereed)
    Abstract [en]

    Electrodes coated with the conducting polymer poly(3,4-ethylene dioxythiophene) (PEDOT) possess attractive electrochemical properties for stimulation or recording in the nervous system. Biomolecules, added as counter ions in electropolymerization, could further improve the biomaterial properties, eliminating the need for surfactant counter ions in the process. Such PEDOT/biomolecular composites, using heparin or hyaluronic acid, have previously been investigated electrochemically. In the present study, their biocompatibility is evaluated. An agarose overlay assay using L929 fibroblasts, and elution and direct contact tests on human neuroblastoma SH-SY5Y cells are applied to investigate cytotoxicity in vitro. PEDOT: heparin was further evaluated in vivo through polymer-coated implants in rodent cortex. No cytotoxic response was seen to any of the PEDOT materials tested. The examination of cortical tissue exposed to polymer-coated implants showed extensive glial scarring irrespective of implant material (Pt:polymer or Pt). However, quantification of immunological response, through distance measurements from implant site to closest neuron and counting of ED1+ cell density around implant, was comparable to those of platinum controls. These results indicate that PEDOT: heparin surfaces were non-cytotoxic and show no marked difference in immunological response in cortical tissue compared to pure platinum controls.

  • 140.
    Asplund, Maria
    et al.
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Thaning, Elin
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Lundberg, Johan
    Sandberg-Nordqvist, Ann-Christin
    Kostyszyn, Beata
    Inganäs, Olle
    von Holst, Hans
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Biocompatibility of PEDOT/biomolecular composites intended for neural communication electrodesManuscript (Other (popular science, discussion, etc.))
    Abstract [en]

    Electrodes of the conjugated polymer poly(3,4-ethylene dioxythiophene) (PEDOT) have been shown to possess very attractive electrochemical properties for functional electrical stimulation (FES) or recording in the nervous system. Biomolecules already present in nervous tissue, added as counter ions in PEDOT electropolymerisation, could be a route to further improve the biomaterial properties of PEDOT, eliminating the need of surfactant counter ions like docedyl benzene sulphonate (DBS) or polystyrene sulphonate (PSS) in the polymerisation process. Such PEDOT/biomolecular composites using heparin, or hyaluronic acid, have been electrochemically investigated in a previous study and have been shown to retain the attractive electrochemical properties already proven for PEDOT:PSS.

     

    The aim of the present study is to evaluate biocompatibility of these PEDOT/biomolecular composites in vitro and also evaluate PEDOT:heparin biocompatibility in cortical tissue in vivo. Hereby, we also aim to identify a suitable test protocol, that can be used in future evaluations when further material developments are made.

     

    Material toxicity was first tested on cell lines, both through a standardised agarose overlay assay on L929 fibroblasts, and through elution tests on human neuroblastoma SH-SY5Y cells. Subsequently, a biocompatibility in vivo test was performed using PEDOT:heparin coated platinum probes implanted in the cerebral cortex of Sprague-Dawley rats. Tissue was collected at three weeks and six weeks of implantation and evaluated by immunohistochemistry.

     

    No cytotoxic response was seen to any of the PEDOT:biomolecular composites tested here. Furthermore, elution tests were found to be a practical and effective way of screening materials for toxicity and had a clear advantage over the agarose overlay assay, which was difficult to apply on other cell types than fibroblasts. Elution tests would therefore be recommendable as a screening method, at all stages of material development. In the in vivo tests, the stiffness of the platinum substrate was a significant problem, and extensive glial scarring was seen in most cases irrespective of implant material. However, quantification of immunological response through distance measurements from implant site to closest neuron, and counting of macrophage densities in proximity to polymer surface, was comparable to those of platinum controls. These results indicate that PEDOT:heparin surfaces were as compatible with cortical tissue as pure platinum controls.

  • 141.
    Asplund, Maria
    et al.
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    von Holst, Hans
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Inganäs, Olle
    Composite biomolecule/PEDOT materials for neural electrodes2008In: Biointerphases, ISSN 1559-4106, Vol. 3, no 3, p. 83-93Article in journal (Refereed)
    Abstract [en]

    Electrodes intended for neural communication must be designed to meet boththe electrochemical and biological requirements essential for long term functionality. Metallic electrode materials have been found inadequate to meet theserequirements and therefore conducting polymers for neural electrodes have emergedas a field of interest. One clear advantage with polymerelectrodes is the possibility to tailor the material to haveoptimal biomechanical and chemical properties for certain applications. To identifyand evaluate new materials for neural communication electrodes, three chargedbiomolecules, fibrinogen, hyaluronic acid (HA), and heparin are used ascounterions in the electrochemical polymerization of poly(3,4-ethylenedioxythiophene) (PEDOT). The resultingmaterial is evaluated electrochemically and the amount of exposed biomoleculeon the surface is quantified. PEDOT:biomolecule surfaces are also studiedwith static contact angle measurements as well as scanning electronmicroscopy and compared to surfaces of PEDOT electrochemically deposited withsurfactant counterion polystyrene sulphonate (PSS). Electrochemical measurements show that PEDOT:heparinand PEDOT:HA, both have the electrochemical properties required for neuralelectrodes, and PEDOT:heparin also compares well to PEDOT:PSS. PEDOT:fibrinogen isfound less suitable as neural electrode material.

  • 142.
    Atefi, Seyed Reza
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Electrical Bioimpedance Cerebral Monitoring: From Hypothesis and Simulation to First Experimental Evidence in Stroke Patients2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Stroke is amongthe leading causes of death worldwide and requires immediate care to prevent death or permanent disability. Unfortunately, the current stateof stroke diagnosis is limited to fixed neuroimaging facilities that do not allow rapid stroke diagnosis. Hence, a portable stroke-diagnosis device could assist in the pre-hospital triage of patients. Moreover, such a portable device could also be useful for bedside stroke monitoring of patients in the Neuro Intensive Care Unit (Neuro-ICU) to avoid unnecessary neuroimaging. Recent animal studies and numerical simulations have supported the idea of implementing Electrical Bioimpedance (EBI) in a portable device, allowing non-invasive assessment as a useful tool for the pre-hospital triage of stroke and Traumatic Brain Injury (TBI) patients. Unfortunately, these studies have not reported any results from human subjects in the acute phase of the stroke. The numerical simulations are also based on simple models that sometimes lack necessary details.

    Finite Element Method (FEM) simulations on a realistic numerical head model as well as experimental Bioimpedance Spectroscopy (BIS) measurements from human subjectsin the acute, subacute and chronic phasesof stroke were used to answer the following research questions: (i) Does stroke modify the electrical properties of brain tissue in a way that is detectable via EBI? (ii) Would it be possible to detect stroke via EBI as early as in the acute and sub-acute phase?(iii) Is EBI sensitive enough to monitor changes caused by stroke pathogenesis?

    Using FEM to simulate electrical current injection on the head and study the resulting distribution of electrical potential on the scalp, it was shown that Intra-Cranial Hemorrhage (ICH) affects the quasi-symmetric scalp potential distribution,creating larger left-right potential asymmetry when compared to the healthy head model. Proof-of-concept FEM simulations were also tested in a small cohort of 6ICH patients and 10 healthy controls, showing that the left-right potential difference in the patients is significantly (p<0.05) larger than in the controls. Using bioimpedance measurements in the acute,  subacute and chronic phasesof stroke and examining simple features, it was also shown that the head EBI measurements of patients suffering stroke are different from controls, enabling the discrimination of healthy controls and stroke patients at any stage of the stroke. The absolute change in test-retest resistance measurements of the control group (~5.33%) was also found to be significantly (p<0.05) smaller than the EBI measurements of patients obtained 24 hours and 72 hours after stroke onset (20.44%). These results suggested that scalp EBI is sensitive to stroke pathogenesis changesand thususeful for bedside monitoring in the Neuro-ICU. These results suggested that EBI is a potentially useful tool for stroke diagnosis and monitoring.

    Finally, the initial observations based on a small number of patients, addressing the proposed future work of this thesis, suggested that the average head resistance amplitude of hemorrhagic stroke patients is smaller than in healthy controls, while ischemic stroke patients show a larger resistance amplitude than the controls. Scalp potential asymmetry analysis of healthy, hemorrhagic and ischemic stroke subjects also suggests that these three groups can be separated. However, these results are based on a small number of patients and need to be validated using a larger cohort. Initial observations also showed that the resistance of the EBI measurements of controls is robust between test and retest measurements, showing no significant difference (less than 2% and p>0.05). Subject position during EBI recording (supine or sitting) did not seem to affect the resistance of the EBI measurements (p>0.05). However, age, sex and head size showed significant effects on the resistance measurements. These initial observations are encouraging for further research on EBI for cerebral monitoring and stroke diagnosis. However, at this stage, considering the uncertainties in stroke type differentiation, EBI cannot replace CT but has the potential to be used as a consultation tool.

  • 143.
    Atefi, Seyed Reza
    et al.
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701).
    Buendia, Ruben
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701).
    Lindecrantz, Kaj
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701).
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701).
    Cole Function and Conductance-Based Parasitic Capacitance Compensation for Cerebral Electrical Bioimpedance Measurements2012In: Engineering in Medicine and Biology Society (EMBC), 2012 Annual International Conference of the IEEE, San Diego: IEEE press , 2012, p. 3368-3371Conference paper (Refereed)
    Abstract [en]

    One of the most common measurement artifacts present in Electrical Bioimpedance Spectroscopy measurements (EBIS) comes from the capacitive leakage effect resulting from parasitic stray capacitances. This artifact produces a deviation in the measured impedance spectrum that is most noticeable at higher frequencies. The artifact taints the spectroscopy measurement increasing the difficulty of producing reliable EBIS measurements at high frequencies. In this work, an approach for removing such capacitive influence from the spectral measurement is presented making use of a novel method to estimate the value of the parasitic capacitance equivalent that causes the measurement artifact. The proposed method has been tested and validated theoretically and experimentally and it gives a more accurate estimation of the value of the parasitic capacitance than the previous methods. Once a reliable value of parasitic capacitance has been estimated the capacitive influence can be easily compensated in the EBIS measured data. Thus enabling analysis of EBIS data at higher frequencies, i.e. in the range of 300-500 kHz like measurements intended for cerebral monitoring, where the characteristic frequency is remarkably higher than EBIS measurements i.e. within the range 30 to 50 kHz, intended for body composition assessment.

  • 144.
    Atefi, Seyed Reza
    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.
    Kamalian, Shervin
    Rosenthal, Eric
    Lev, Michael
    Bonmassar, Giorgio
    Intracranial haemorrhage alters scalp potential distributions in bioimpedance cerebral monitoring applications: preliminary results from FEM simulation on a realistic head model and human subjects2016In: Medical Physics, ISSN 2473-4209, Vol. 43, no 2, p. 675-686Article in journal (Refereed)
    Abstract [en]

    Purpose: Current diagnostic neuroimaging for detection of intracranial hemorrhage (ICH) is limited to fixed scanners requiring patient transport and extensive infrastructure support. ICH diagnosis would therefore benefit from a portable diagnostic technology, such as electrical bioimpedance (EBI). Through simulations and patient observation, the authors assessed the influence of unilateral ICH hematomas on quasisymmetric scalp potential distributions in order to establish the feasibility of EBI technology as a potential tool for early diagnosis. Methods: Finite element method (FEM) simulations and experimental leftright hemispheric scalp potential differences of healthy and damaged brains were compared with respect to the asymmetry caused by ICH lesions on quasisymmetric scalp potential distributions. In numerical simulations, this asymmetry was measured at 25 kHz and visualized on the scalp as the normalized potential difference between the healthy and ICH damaged models. Proof-of-concept simulations were extended in a pilot study of experimental scalp potential measurements recorded between 0 and 50 kHz with the authors custom-made bioimpedance spectrometer. Mean leftright scalp potential differences recorded from the frontal, central, and parietal brain regions of ten healthy control and six patients suffering from acute/subacute ICH were compared. The observed differences were measured at the 5% level of significance using the two-sample Welch ttest. Results: The 3D-anatomically accurate FEM simulations showed that the normalized scalp potential difference between the damaged and healthy brain models is zero everywhere on the head surface, except in the vicinity of the lesion, where it can vary up to 5%. The authors preliminary experimental results also confirmed that the leftright scalp potential difference in patients with ICH (e.g., 64 mV) is significantly larger than in healthy subjects (e.g., 20.8 mV; P < 0.05). Conclusions: Realistic, proof-of-concept simulations confirmed that ICH affects quasisymmetric scalp potential distributions. Pilot clinical observations with the authors custom-made bioimpedance spectrometer also showed higher leftright potential differences in the presence of ICH, similar to those of their simulations, that may help to distinguish healthy subjects from ICH patients. Although these pilot clinical observations are in agreement with the computer simulations, the small sample size of this study lacks statistical power to exclude the influence of other possible confounders such as age, ex, and electrode positioning. The agreement with previously published simulation-based and clinical results, however, suggests that EBI technology may be potentially useful for ICH detection. © 2016 American Association of Physicists in Medicine.

  • 145.
    Atefi, Seyed Reza
    et al.
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Lindecrantz, Kaj
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS).
    Electrical Bioimpedance cerebral monitoring. Preliminary results from measurements on stroke patients2012In: Engineering in Medicine and Biology Society (EMBC), 2012 Annual International Conference of the IEEE, IEEE , 2012, p. 126-129Conference paper (Refereed)
    Abstract [en]

    Electrical Bioimpedance Spectroscopy (EBIS) is currently used in different tissue characterization applications. In this work we aim to use EBIS to study changes in electrical properties of the cerebral tissues after an incident of hemorrhage/ischemic stroke. To do so a case-control study was conducted using six controls and three stroke cases. The preliminary results of this study show that by using Cole-based analysis on EBIS measurements and analyzing the Cole parameters R0 and R∞, it is possible to detect changes on electrical properties of cerebral tissue after stroke. 

  • 146.
    Atefi, Seyed Reza
    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.
    Study of the dynamics of transcephalic cerebral impedance data during cardio-vascular surgery2013In: XV International Conference on Electrical Bio-Impedance (ICEBI) & XIV Conference on Electrical Impedance Tomography (EIT), Institute of Physics (IOP), 2013, Vol. 434, no 1, p. 012045-Conference paper (Refereed)
    Abstract [en]

    Postoperative neurological deficits are one of the risks associated with cardio vascular surgery, necessitating development of new techniques for cerebral monitoring. In this study an experimental observation regarding the dynamics of transcephalic Electrical Bioimpedance (EBI) in patients undergoing cardiac surgery with and without extracorporeal circulation (ECC) was conducted to investigate the potential use of electrical Bioimpedance for cerebral monitoring in cardio vascular surgery. Tetrapolar transcephalic EBI measurements at single frequency of 50 kHz were recorded prior to and during cardio vascular surgery. The obtained results show that the transcephalic impedance decreases in both groups of patients as operation starts, however slight differences in these two groups were also observed with the cerebral impedance reduction in patients having no ECC being less common and not as pronounced as in the ECC group. Changes in the cerebral impedance were in agreement with changes of haematocrit and temperature. The origin of EBI changes is still unexplained however these results encourage us to continue investigating the application of electrical bioimpedance cerebral monitoring clinically.

  • 147.
    Atefi, Seyed Reza
    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.
    Thorlin, Thorleif
    Lindecrantz, Kaj
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Stroke Damage Detection Using Classification Trees on Electrical Bioimpedance Cerebral Spectroscopy Measurements2013In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 13, no 8, p. 10074-10086Article in journal (Refereed)
    Abstract [en]

    After cancer and cardio-vascular disease, stroke is the third greatest cause of death worldwide. Given the limitations of the current imaging technologies used for stroke diagnosis, the need for portable non-invasive and less expensive diagnostic tools is crucial. Previous studies have suggested that electrical bioimpedance (EBI) measurements from the head might contain useful clinical information related to changes produced in the cerebral tissue after the onset of stroke. In this study, we recorded 720 EBI Spectroscopy (EBIS) measurements from two different head regions of 18 hemispheres of nine subjects. Three of these subjects had suffered a unilateral haemorrhagic stroke. A number of features based on structural and intrinsic frequency-dependent properties of the cerebral tissue were extracted. These features were then fed into a classification tree. The results show that a full classification of damaged and undamaged cerebral tissue was achieved after three hierarchical classification steps. Lastly, the performance of the classification tree was assessed using Leave-One-Out Cross Validation (LOO-CV). Despite the fact that the results of this study are limited to a small database, and the observations obtained must be verified further with a larger cohort of patients, these findings confirm that EBI measurements contain useful information for assessing on the health of brain tissue after stroke and supports the hypothesis that classification features based on Cole parameters, spectral information and the geometry of EBIS measurements are useful to differentiate between healthy and stroke damaged brain tissue.

  • 148.
    Atefi, Seyed Reza
    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.
    Tomner, Jens
    Kostulas, Konstantinos
    Lindecrantz, Kaj
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Bonmassar, Giorgio
    Stroke Pathogenesis Alters Dielectric Properties of Brain Tissue Supporting Electrical Bioimpedance Technology as a tool for Cerebral MonitoringManuscript (preprint) (Other academic)
  • 149.
    Axelsson, Pelle
    et al.
    KTH, School of Technology and Health (STH).
    Torelm, Marcus
    KTH, School of Technology and Health (STH).
    Cost-benefit-analys av optisk 3D-scanner2011Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 150.
    Axtelius, Mathias
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Alsawadi, Rami
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    An improved selection algorithm for access points in wireless local area networks: An improved selection algorithm for wireless iopsys devices2016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Wireless devices search for access points when they want to connect to a network. A devicechooses an access point based on the received signal strength between the device and theaccess point. That method is good for staying connected in a local area network but it doesnot always offer the best performance, which can result in a slower connection. This is thestandard method of connection for wireless clients, which will be referred to as the standardprotocol. Larger networks commonly have a lot of access points in an area, which increasesthe coverage area and makes loss of signal a rare occurrence. Overlapping coverage zonesare also common, offering multiple choices for a client. The company Inteno wanted an alternativeconnection method for their gateways. The new method that was developed wouldforce the client to connect to an access point depending on the bitrate to the master, as wellas the received signal strength. These factors are affected by many different parameters.These parameters were noise, signal strength, link-rate, bandwidth usage and connectiontype. A new metric had to be introduced to make the decision process easier by unifying theavailable parameters. The new metric that was introduced is called score. A score system wascreated based on these metrics. The best suited access point would be the one with the highestscore. The developed protocol chose the gateway with the highest bitrate available, while thestandard protocol would invariably pick the closest gateway regardless. The developed protocolcould have been integrated to the standard protocol to gain the benefits of both. Thiscould not be accomplished since the information was not easily accessible on Inteno’s gatewaysand had to be neglected in this thesis.

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