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  • 2251.
    Wu, Weiling
    KTH, School of Technology and Health (STH).
    Carbon Footprint: A case study on the municipality of Haninge2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    AbstractCarbon Footprints, as an indicator of climate performance, help identify major GHG emission sources and potential areas of improvement. In the context of greatly expanding sub-national climate efforts, research on Carbon Footprint accounting at municipality level is timely and necessary to facilitate the establishment of local climate strategies. This study aims at exploring the methodologies for Carbon Footprint assessment at municipality level, based on the case study of Haninge municipality in Sweden. In the study, a Greenhouse Gas inventory of Haninge is developed and it is discussed how the municipality can reduce its Carbon Footprint. The Carbon Footprint of Haninge is estimated to be more than 338,225 tonnesCO2eq, and 4.5 tonnes CO2eq per capita. These numbers are twice as large as the production-based emissions, which are estimated to be 169,024 tonnes CO2eq in total, and approximately 2.3 tonnes CO2eq per capita. Among them the most important parts are emissions caused by energy use, and indirect emissions caused by local private consumption. It is worth noting that a large proportion of emissions occur outside Haninge as a result of local consumption. Intensive use of biomass for heat production and electricity from renewable sources and nuclear power have significantly reduced the climate impact of Haninge. The major barrier for Carbon Footprint accounting at municipality level is lack of local statistics. In the case of Sweden, several databases providing emission statistics are used in the research, including KRE, RUS, NIR and Environmental Account.

     

  • 2252. Wulff, Ragna
    et al.
    Lundqvist, Joakim
    Rutsdottir, Gudrun
    Hansson, Andreas
    Stenbaek, Anders
    Elmlund, Dominika
    KTH, School of Technology and Health (STH), Structural Biotechnology.
    Elmlund, Hans
    Jensen, Paul Erik
    Hansson, Mats
    NADPH-dependent thioredoxin reductase C and its possible involvement in the cyclase reaction of the chlorophyll biosynthetic pathwayManuscript (preprint) (Other academic)
  • 2253. Wulff, Ragna Peterson
    et al.
    Lundqvist, Joakim
    Rutsdottir, Gudrun
    Hansson, Andreas
    Stenbaek, Anne
    Elmlund, Dominika
    KTH, School of Technology and Health (STH), Structural Biotechnology.
    Elmlund, Hans
    Jensen, Poul Erik
    Hansson, Mats
    The Activity of Barley NADPH-Dependent Thioredoxin Reductase C Is Independent of the Oligomeric State of the Protein: Tetrameric Structure Determined by Cryo-Electron Microscopy2011In: Biochemistry, ISSN 0006-2960, E-ISSN 1520-4995, Vol. 50, no 18, 3713-3723 p.Article in journal (Refereed)
    Abstract [en]

    Thioredoxin and thioredoxin reductase can regulate cell metabolism through redox regulation of disulfide bridges or through removal of H2O2. These two enzymatic functions are combined in NADPH-dependent thioredoxin reductase C (NTRC), which contains an N-terminal thioredoxin reductase domain fused with a C-terminal thioredoxin domain. Rice NTRC exists in different oligomeric states, depending on the absence or presence of its NADPH cofactor. It has been suggested that the different oligomeric states may have diverse activity. Thus, the redox status of the chloroplast could influence the oligomeric state of NTRC and thereby its activity. We have characterized the oligomeric states of NTRC from barley (Hard rum vulgare L.). This also includes a structural model of the tetrameric NTRC derived from cryo-electron microscopy and single-particle reconstruction. We conclude that the tetrameric NTRC is a dimeric arrangement of two NTRC homodimers. Unlike that of rice NTRC, the quaternary structure of barley NTRC complexes is unaffected by addition of NADPH. The activity of NTRC was tested with two different enzyme assays. The N-terminal part of NTRC was tested in a thioredoxin reductase assay. A peroxide sensitive Mg-protoporphyrin IX monomethyl ester (MPE) cyclase enzyme system of the chlorophyll biosynthetic pathway was used to test the catalytic ability of both the N- and C-terminal parts of NTRC. The different oligomeric assembly states do not exhibit significantly different activities. Thus, it appears that the activities are independent of the oligomeric state of barley NTRC.

  • 2254. Wågström, Elle
    et al.
    Johnson, Jonas
    KTH, School of Technology and Health (STH), Medical Engineering.
    Ferm-Widlund, Kjerstin
    Elmstedt, Nina
    KTH, School of Technology and Health (STH), Medical Engineering.
    Liuba, Karina
    Lind, Britta
    KTH, School of Technology and Health (STH), Medical Engineering.
    Brodin, Lars-Åke
    KTH, School of Technology and Health (STH), Medical Engineering.
    Lundbäck, Stig
    Westgren, Magnus
    The cardiac state diagram as a novel approach for the evaluation of pre- and post-ejection phases of the cardiac cycle in asphyxiated fetal lambs2013In: Ultrasound in Medicine and Biology, ISSN 0301-5629, E-ISSN 1879-291X, Vol. 39, no 9, 1682-1687 p.Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to investigate myocardial wall motion using echocardiography and color-coded tissue velocity imaging and to generate a cardiac state diagram for evaluation of the duration of the pre- and post-ejection phases in asphyxiated fetal lambs. Six near-term lambs were partly exteriorized and brought to cardiac arrest through asphyxia. Echocardiography measurements were recorded simultaneously with arterial blood sampling for lactate and blood gases. All fetal lambs exhibited prolongation of the pre- and post-ejection phases at the time when the most pronounced changes in lactate concentration and pH occurred. The mean change in duration of the pre- and post-ejection phases for all fetal lambs was 36 +/- 7 ms (p < 0.002) and 77 +/- 17 ms (p < 0.019), respectively, and the percentage change was 50% (p < 0.001) and 38% (p < 0.049), respectively. As asphyxia progressed in fetal lambs, the duration of the pre- and post-ejection phases increased. The cardiac state diagram has the potential to be a comprehensible tool for detecting fetal asphyxia.

  • 2255. Wågström, Elle
    et al.
    Johnson, Jonas
    KTH, School of Technology and Health (STH), Medical Engineering.
    Ferm-Widlund, Kjerstin
    Elmstedt, Nina
    KTH, School of Technology and Health (STH), Medical Engineering.
    Liuba, Karina
    Lind, Britta
    KTH, School of Technology and Health (STH), Medical Engineering.
    Brodin, Lars-Åke
    KTH, School of Technology and Health (STH), Medical Engineering.
    Westgren, Magnus
    The Cardiac State Diagram as a novel approach for evaluation of phases of the cardiac cycle in asfyxiated fetal lambs2012In: Acta Obstetricia et Gynecologica Scandinavica, ISSN 0001-6349, E-ISSN 1600-0412, Vol. 91, 144-144 p.Article in journal (Other academic)
  • 2256.
    Wåhslén, Jonas
    KTH, School of Technology and Health (STH), Data- och elektroteknik.
    Multi-Sensor Data Synchronization using Mobile Phones2013Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Body sensor networking is a rapidly growing technology. Today wearable sensors are used to measure and monitor e.g. pulse, temperature, skin conductance, heart activity, and movement (through GPS or inertial measurement units). Mobile phones can act as coordinating nodes in wireless personal area networks used in home automation, healthcare, sport and wellness e.g. to measure pulse and distance. Integration of data from multiple sources sensors (data fusion) means that data from each sensor node needs to be associated with data from other sensor nodes sampled at approximately the same time. Accurate methods for time synchronization are therefore a necessary prerequisite for reliable data fusion.

    This thesis studies time synchronization problems in Bluetooth piconets between multiple wireless sensor nodes connected to a mobile phone that acts as coordinating node. Three different algorithms to enable correct data fusion have been developed, implemented and evaluated. The first is a single clock solution that synchronizes multiple wireless sensor nodes based solely on the mobile phone’s clock. The other two algorithms synchronize the clocks in sensor nodes to the clock in the coordinating node. 

  • 2257.
    Wåhslén, Jonas
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Lindh, Thomas
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Real-time Performance Management of Assisted Living Services for Bluetooth Low Energy Sensor Communication2017In: Integrated Network and Service Management (IM), 2017 IFIP/IEEE Symposium on, IEEE conference proceedings, 2017Conference paper (Refereed)
    Abstract [en]

    PerfMon is a prototype implementation of a realtime performance management method for sensor data communication in assisted living applications. It is implemented in accordance with the specification for GATT services in Bluetooth low energy (BLE). PerfMon provides a tool for real-time performance monitoring and control for caregivers and service providers. Test results from monitoring and control of packet loss ratio related to alarm thresholds are presented. PerfMon is adapted to cloud-based web services using RESTful APIs and established object models. Performance management is a necessary component in an overall management system of IoT devices for healthcare and assisted living applications.

  • 2258.
    Wåhslén, Jonas
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Lindh, Thomas
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Smartphone-Centric Wi-Fi Device-to-Device Sensor Communication for User Mobility in AAL Services2016In: Personal, Indoor, and Mobile Radio Communications (PIMRC), 2016 IEEE 27th Annual International Symposium on, IEEE conference proceedings, 2016, 80-85 p.Conference paper (Refereed)
    Abstract [en]

    This paper evaluates a use-case for smartphone-centric Wi-Fi device-to-device sensor communication that enables user mobility in ambient assisted living (AAL) services. A real-time performance measurement method has been developed and implemented to evaluate the smartphone’s ability to act as a hub and gateway for Wi-Fi connected sensor nodes. The results show that Wi-Fi Direct and Wi-Fi Hotspot are feasible solutions for smartphone-centric device-to-device communication that enables user mobility. In addition, a cloud-based web application for monitoring and displaying sensor data has been implemented.

  • 2259.
    Wåhslén, Jonas
    et al.
    KTH, School of Technology and Health (STH), Data- och elektroteknik (Closed 20130701).
    Lindh, Thomas
    KTH, School of Technology and Health (STH), Data- och elektroteknik (Closed 20130701).
    Eriksson, Martin
    KTH, School of Technology and Health (STH).
    A novel approach to multi-sensor data synchronization using mobile phones2011In: Proceedings of the 5th International ICST Conference on Body Area Networks: BodyNets 2010, 2011, 171-174 p.Conference paper (Refereed)
    Abstract [en]

    This paper presents a new algorithm for synchronization of data from multiple sensors arriving to a mobile phone's Bluetooth interface with possibly unknown and different sampling frequencies. A system that provides feedback signals to an athlete is one example where it is crucial to synchronize data from several wireless sensors; especially sensor nodes use different and unknown sampling rates.

  • 2260.
    Wåhslén, Jonas
    et al.
    KTH, School of Technology and Health (STH), Data- och elektroteknik (Closed 20130701).
    Orhan, Ibrahim
    KTH, School of Technology and Health (STH), Data- och elektroteknik (Closed 20130701).
    Lindh, Thomas
    KTH, School of Technology and Health (STH).
    Local Time Synchronization in Bluetooth Piconets for Data Fusion Using Mobile Phones2011In: BSN 2011: 8th International Conference on Body Sensor Networks, 2011, 113-138 p.Conference paper (Refereed)
    Abstract [en]

    This paper presents a method to synchronize the clocks in a Bluetooth piconet from the application layer in a mobile phone. It adapts algorithms for time synchronization of distributed systems and the Internet to Bluetooth networks. The performance issues that cause problems for data synchronization between master and slaves in Bluetooth are highlighted. The tests show that the synchronization error is limited to one sampling time.

  • 2261.
    Wåhslén, Jonas
    et al.
    KTH, School of Technology and Health (STH), Data- och elektroteknik (Closed 20130701).
    Orhan, Ibrahim
    KTH, School of Technology and Health (STH), Data- och elektroteknik (Closed 20130701).
    Lindh, Thomas
    KTH, School of Technology and Health (STH), Data- och elektroteknik (Closed 20130701).
    Eriksson, Martin
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701).
    A novel approch to multi-sensor data synchronisation using mobile phones2013In: International Journal of Autonomous and Adaptive Communications Systems, ISSN 1754-8632, E-ISSN 1754-8640, Vol. 6, no 3, 289-303 p.Article in journal (Refereed)
    Abstract [en]

    This paper presents a new algorithm for application layer synchronisation of data from multiple sensors arriving to a mobile phone's Bluetooth interface. A system that provides feedback signals to an athlete is one example where it is crucial to synchronise data from several wireless sensors. This paper also discusses synchronisation problems caused by unpredictable Bluetooth transmission performance. 

  • 2262.
    Wåhslén, Jonas
    et al.
    KTH, School of Technology and Health (STH), Data- och elektroteknik (Closed 20130701).
    Orhan, Ibrahim
    KTH, School of Technology and Health (STH), Data- och elektroteknik (Closed 20130701).
    Sturm, Dennis
    KTH, School of Technology and Health (STH), Centres, Centre for Technology in Medicine and Health, CTMH.
    Lindh, Thomas
    KTH, School of Technology and Health (STH), Data- och elektroteknik (Closed 20130701).
    Performance evaluation of time synchronization and clock drift compensation in wireless personal area networks2012In: BodyNets '12 Proceedings of the 7th International Conference on Body Area Networks, ICST , 2012, 153-158 p.Conference paper (Refereed)
    Abstract [en]

    Efficient algorithms for time synchronization, including compensation for clock drift, are essential in order to obtain reliable fusion of data samples from multiple wireless sensor nodes. This paper evaluates the performance of algorithms based on three different approaches; one that synchronizes the local clocks on the sensor nodes, and a second that uses a single clock on the receiving node (e.g. a mobile phone), and a third that uses broadcast messages. The performances of the synchronization algorithms are evaluated in wireless personal area networks, especially Bluetooth piconets and ZigBee/IEEE 802.15.4 networks. A new approach for compensation of clock drift and a realtime implementation of single node synchronization from the mobile phone are presented and tested. Finally, applications of data fusion and time synchronization are shown in two different use cases; a kayaking sports case, and monitoring of heart and respiration of prematurely born infants. 

  • 2263.
    Wåhslén, Jonas
    et al.
    KTH, School of Technology and Health (STH), Data- och elektroteknik (Closed 20130701).
    Sturm, Dennis
    KTH, School of Technology and Health (STH), Centres, Centre for Technology in Medicine and Health, CTMH.
    ExecutiveSummary of AugmentIT: A Smart Phone App that generates kinematic feedback based on augmented reality data e.g. vidoeo and IMU (or other sensor) data2012Other (Other (popular science, discussion, etc.))
  • 2264.
    Xie, Li
    et al.
    KTH, School of Information and Communication Technology (ICT), Electronic Systems. KTH, School of Information and Communication Technology (ICT), Centres, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK.
    Yang, Geng
    KTH, School of Information and Communication Technology (ICT), Electronic Systems. KTH, School of Information and Communication Technology (ICT), Centres, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK.
    Xu, Linlin
    KTH, School of Information and Communication Technology (ICT), Centres, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK.
    Seoane, Fernando
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems.
    Chen, Qiang
    KTH, School of Information and Communication Technology (ICT), Electronic Systems. KTH, School of Information and Communication Technology (ICT), Centres, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK.
    Zheng, Lirong
    KTH, School of Information and Communication Technology (ICT), Electronic Systems. KTH, School of Information and Communication Technology (ICT), Centres, VinnExcellence Center for Intelligence in Paper and Packaging, iPACK. State Key Laboratory of ASICs and Systems, Fudan University, 200433, Shanghai, China .
    Characterization of dry biopotential electrodes2013In: Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS, 2013, 1478-1481 p.Conference paper (Refereed)
    Abstract [en]

    Driven by the increased interest in wearable long-term healthcare monitoring systems, varieties of dry electrodes are proposed based on different materials with different patterns and structures. Most of the studies reported in the literature focus on proposing new electrodes and comparing its performance with commercial electrodes. Few papers are about detailed comparison among different dry electrodes. In this paper, printed metal-plate electrodes, textile based electrodes, and spiked electrodes are for the first time evaluated and compared under the same experimental setup. The contact impedance and noise characterization are measured. The in-vivo electrocardiogram (ECG) measurement is applied to evaluate the overall performance of different electrodes. Textile electrodes and printed electrodes gain comparable high-quality ECG signals. The ECG signal obtained by spiked electrodes is noisier. However, a clear ECG envelope can be observed and the signal quality can be easily improved by backend signal processing. The features of each type of electrodes are analyzed and the suitable application scenario is addressed.

  • 2265. Xiu, L.
    et al.
    Svensson, V.
    Johansson, E.
    Ek, A.
    Marcus, C.
    Ekstedt, M.
    KTH, School of Technology and Health (STH).
    Bedtime eating and sleep disturbances among 2 years old children2016In: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 25, 326-327 p.Article in journal (Other academic)
  • 2266.
    Xu, Jia Cheng
    et al.
    KTH, School of Technology and Health (STH).
    Jildenbäck, Manne
    KTH, School of Technology and Health (STH).
    Förbättring av energieffektivitet vid gång: En studie på patienter med höftledsartros efter total höftledsplastik2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Hip osteoarthritis is a common disease associated with everyday pain and limited mobility. This causes a change in gait characteristics during walking, which tends to give a lower energy efficiency than normal. For patients with hip osteoarthritis, hip arthroplasty is considered a last option due to the related risks of a surgery.

    To investigate whether the patients show signs of improvement after the surgery, through an energy efficiency standpoint, data have been collected through a gait analysis. In this study, gait analysis was performed on a healthy reference group to obtain reference data. Data from the patient group, which consisted of patients with hip osteoarthritis pre- and post surgery using total hip arthroplasty, THA, was given by Karolinska Institutet. To determine if THA is an appropriate action, data from the patients were compared to the reference data.

    By performing and collecting data through a gait analysis on a healthy reference group and on patients with hip osteoarthritis pre- and post surgery using total hip arthroplasty, THA, this study has investigated whether the patients show signs of improvement after the surgery and also if the patients differentiate from the reference group through an energy efficiency standpoint. This is used to determine whether THA is an appropriate action.

     The study showed a difference in energy efficiency pre- and post surgery. An obvious improvement after THA was shown in most of the patients (p = 0,0094). However, 36 % showed in at least one case, decreased- or an unchanged value in energy efficiency. Although, through an average standpoint only two patients showed decreased efficiency, but the patients after THA only reached an energy efficiency that was approximately half the efficiency of the reference group.

    The results in this study indicates that further studies are necessary. Considerable alternatives to THA, especially surface hip arthroplasty, SRA, as well as parameters such as pain and mobility should be examined with respect to energy efficiency. Until then, hip arthroplasty should still be considered a last option for patients.

  • 2267.
    Xu, Xiayu
    et al.
    School of Life Science and Technology,Xián University, Xián, China.
    Akay, Altug
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    Wei, Huilin
    Wang, ShuQi
    Pingguan-Murphy, Belinda
    Erlandsson, Björn-Erik
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    Li, Xiujun
    Lee, Wongu
    Hu, Jie
    Wang, Lin
    Xu, Feng
    Advances in Smartphone-Based Point-of-Care Diagnostics: This paper reviews the state-of-the-art advances in smartphone-based point-of-care diagnostic technologies and their applications in medicine and biology.2015In: Proceedings of the IEEE, ISSN 0018-9219, E-ISSN 1558-2256, Vol. 103, no 2, 236-247 p.Article in journal (Refereed)
    Abstract [en]

    Point-of-care (POC) diagnostics is playing an increasingly important role in public health, environmental monitoring, and food safety analysis. Smartphones, alone or in conjunction with add-on devices, have shown great capability of data collection, analysis, display, and transmission, making them popular in POC diagnostics. In this article, the state-ofthe- art advances in smartphone-based POC diagnostic technologies and their applications in the past few years are outlined, ranging from in vivo tests that use smartphone’s built-in/external sensors to detect biological signals to in vitro tests that involves complicated biochemical reactions. Novel techniques are illustrated by a number of attractive examples, followed by a brief discussion of the smartphone’s role in telemedicine. The challenges and perspectives of smartphonebased POC diagnostics are also provided.

  • 2268. Yamamoto, T.
    et al.
    Nascimento, M. M.
    Hayashi, Shirley Y.
    KTH, School of Technology and Health (STH), Medical Engineering.
    Qureshi, A. R.
    Waniewski, J.
    Brodin, L. A.
    Anderstam, B.
    Lind, B.
    Riella, M. C.
    Seeberger, A.
    Lindholm, B.
    Changes in circulating biomarkers during a single hemodialysis session2013In: Hemodialysis International, ISSN 1492-7535, E-ISSN 1542-4758, Vol. 17, no 1, 59-66 p.Article in journal (Refereed)
    Abstract [en]

    The hemodialysis (HD) procedure induces an inflammatory response potentially contributing to cardiovascular disease. Here we investigated the acute impact of HD on circulating biomarkers. Circulating biomarkers (small solutes, middle molecular-sized peptides, and proteins) related to inflammation, oxidative stress, and vascular calcification (VC) were measured before and after a single session of HD in 45 clinically stable patients. Concentrations were corrected for ultrafiltration-induced hemoconcentration. Among vascular calcification-related biomarkers, osteoprotegerin and fetuin-A remained unchanged while fibroblast growth factor-23 (FGF23) decreased by -19%. Changes of FGF23 and changes of phosphate correlated (ρ=0.61, P<0.001). While C-reactive protein did not change, interleukin-6 (IL-6) increased by 14% and pentraxin 3 (PTX3) increased by 45%. IL-6 and PTX3 appear to be valid biomarkers of the intradialytic inflammatory response. VC-related markers were in general not affected by the single HD session; however, the observed correlation between acute changes of FGF-23 and phosphate during HD warrants further studies.

  • 2269. Yamazaki, Junya
    et al.
    Gilgien, Matthias
    Kleiven, Svein
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    McIntosh, Andrew S.
    Nachbauer, Werner
    Müller, Erich
    Bere, Tone
    Bahr, Roald
    Krosshaug, Tron
    Analysis of a Severe Head Injury in World Cup Alpine Skiing: A Case Report.2015In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 47, no 6, 1113-1118 p.Article in journal (Refereed)
    Abstract [en]

    Traumatic brain injury (TBI) is the leading cause of death in alpine skiing. It has been found that helmet use can reduce the incidence of head injuries between 15% and 60%. However, knowledge on optimal helmet performance criteria in World Cup alpine skiing is currently limited owing to the lack of biomechanical data from real crash situations. Purpose: This study aimed to estimate impact velocities in a severe TBI case in World Cup alpine skiing. Methods: Video sequences from a TBI case in World Cup alpine skiing were analyzed using a model-based image matching technique. Video sequences from four camera views were obtained in full high-definition (1080p) format. A three-dimensional model of the course was built based on accurate measurements of piste landmarks and matched to the background video footage using the animation software Poser 4. A trunk-neck-head model was used for tracking the skier's trajectory. Results: Immediately before head impact, the downward velocity component was estimated to be 8 m.s(-1). After impact, the upward velocity was 3 m.s(-1), whereas the velocity parallel to the slope surface was reduced from 33 m.s(-1) to 22 m.s(-1). The frontal plane angular velocity of the head changed from 80 radIsj1 left tilt immediately before impact to 20 rad.s(-1) right tilt immediately after impact. Conclusions: A unique combination of high-definition video footage and accurate measurements of landmarks in the slope made possible a high-quality analysis of head impact velocity in a severe TBI case. The estimates can provide crucial information on how to prevent TBI through helmet performance criteria and design.

  • 2270.
    Yang, Liyun
    KTH, School of Technology and Health (STH).
    Development and validation of a novel iOS application for measuring arm inclination2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Work in demanding postures is a known risk factor for work-related musculoskeletal disorders (MSDs), specifically work with elevated arms may cause neck/shoulder disorders. Such a disorder is a tragedy for the individual, and costly for society. Technical measurements are more precise in estimating the work exposure, than observation and self-reports, and there is a need for uncomplicated methods for risk assessments. The aim of this project was to develop and validate an iOS application for measuring arm elevation angle.

    Such an application was developed, based on the built-in accelerometer and gyroscope of the iPhone/iPod Touch. The application was designed to be self-exploratory. Directly after a measurement, 10th, 50th and 90th percentiles of angular distribution and median angular velocity, and percentage of time above 30°, 60°, and 90° are presented. The focused user group, ergonomists, was consulted during the user interface design phase. Complete angular datasets may be exported via email as text files for further analyses.

    The application was validated by comparison to the output of an optical motion capture system for four subjects. The two methods correlated above 0.99, with absolute error below 4.8° in arm flexion and abduction positions. During arm swing movements, the average root-mean-square differences (RMSDs) were 3.7°, 4.6° and 6.5° for slow (0.1 Hz), medium (0.4 Hz) and fast (0.8 Hz) arm swings, respectively. For simulated painting, the mean RMSDs was 5.5°.

    Since the accuracy was similar to other tested field research methods, this convenient and “low-cost” application should be useful for ergonomists, for risk assessments or educational use. The plan is to publish this iOS application on Apple Store (Apple Inc.) for free. New user feedback may further improve the user interface.

  • 2271.
    Yang, Liyun
    et al.
    KTH, School of Technology and Health (STH), Health Systems Engineering, Ergonomics.
    Grooten, W. J. A.
    Forsman, M.
    An iPhone application for upper arm posture and movement measurements2017In: Applied Ergonomics, ISSN 0003-6870, E-ISSN 1872-9126, Vol. 65, 492-500 p.Article in journal (Refereed)
    Abstract [en]

    There is a need for objective methods for upper arm elevation measurements for accurate and convenient risk assessments. The aims of this study were (i) to compare a newly developed iOS application (iOS) for measuring upper arm elevation and angular velocity with a reference optical tracking system (OTS), and (ii) to compare the accuracy of the iOS incorporating a gyroscope and an accelerometer with using only an accelerometer, which is standard for inclinometry. The iOS-OTS limits of agreement for static postures (9 subjects) were -4.6° and 4.8°. All root mean square differences in arm swings and two simulated work tasks were <6.0°, and all mean correlation coefficients were >0.98. The mean absolute iOS-OTS difference of median angular velocity was <13.1°/s, which was significantly lower than only using an accelerometer (<43.5°/s). The accuracy of this iOS application compares well to that of today's research methods and it can be useful for practical upper arm measurements.

  • 2272.
    Yang, Zhen
    KTH, School of Technology and Health (STH).
    Ståställningens påverkan på lederna i de nedre extremiteterna: en pilotstudie2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Barn med en allvarlig cerebral pares (CP) diagnos har begränsad eller obefintlig förmåga att stå självständigt. Tillståndet medför även en stor risk för subluxation i höftlederna. En befintlig teori bland ortopeder och sjukgymnaster idag är att hjälpmedel för ståträning för barn med CP, såsom ståskal, med höfter i ett abducerade läge kan motverka höftledernas negativa utveckling. Hittills saknas det dock vetenskapliga bevis för denna teori.

    TeamOlmed Barn & Ungdom tillverkar ståskal med 30 graders abduktionsvinkel enligt teorin ovan. Men kunskaperna inom området är begränsade och företaget önskade undersöka om hypotesen stämmer och hur de biomekaniska förutsättningarna påverkas av ståskalen.

    Detta examensarbete fokuserar på olika ståställningar i abduktion för en frisk person och dess inverkan i de nedre extremiteterna i syfte att undersöka den befintliga teorin. Rörelseanalyssystemet Vicon Nexus användes för datainsamling och analys av moment kring knälederna. Vid analys av krafterna i höftlederna användes OpenSim, ett simuleringsprogram för det muskuloskeletala systemet i 3D.

    Resultatet från Vicon visar att knäna har ett inre varusmoment i frontalplanet, vilket är ofarligt för knälederna, i såväl abducerade som vanlig höftposition. Simuleringsresultatet från OpenSim visar att kraftvektorernas riktningar ändras i samband med ändringar av abduktionsvinklar. Detta betyder att kraftvektorernas riktningar i höfterna, uttryckta i femurs koordinatsystem, är snarlika för ståpositioner med olika abduktionsvinklar. Beloppet av kontaktkraften ökade dock med ökande höftabduktionsvinkel.

    Momenten som uppstår vid olika ståställningar är ofarliga för knälederna och kraftvektorernas riktningar i höfterna är oberoende av abduktionsvinklarna för en frisk person. Den enda skillnaden i höftbelastning med stående i höftabduktion var ökade belopp av höftkontaktkrafter. För att noggrannt kunna utvärdera huruvida en ökad kontaktkraft kan påverka höftens tendens att migrera ur led, samt huruvida liknande observationer finns hos patienter med CP skador i sina ståskal, krävs det vidare studier. Tack vare observationerna av denna pilotstudie kan man ställa mer relevanta studiefrågor kring biomekaniska mekanismer i en större studie med barn med CP-diagnoser.

  • 2273.
    Ye, Luming
    KTH, School of Technology and Health (STH), Medical Engineering.
    Perception Metrics in Medical Imaging2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 2274. Yogev, Daniel
    et al.
    Eiken, Ola
    KTH, School of Technology and Health (STH), Environmental Physiology.
    Pisot, Rado
    Biolo, Gianni
    di Prampero, Pietro
    Narici, Marco
    Mekjavic, Igor B.
    Effect of 21 days of horizontal bed rest on behavioural thermoregulation2010In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 108, no 2, 281-288 p.Article in journal (Refereed)
    Abstract [en]

    The present study investigated the effect of 21 days of horizontal bed rest on cutaneous cold and warm sensitivity, and on behavioural temperature regulation. Healthy male subjects (N = 10) were accommodated in a hospital ward for the duration of the study and were under 24-h medical care. All activities (eating, drinking, hygiene, etc.) were conducted in the horizontal position. On the 1st and 22nd day of bed rest, cutaneous temperature sensitivity was tested by applying cold and warm stimuli of different magnitudes to the volar region of the forearm via a Peltier element thermode. Behavioural thermoregulation was assessed by having the subjects regulate the temperature of the water within a water-perfused suit (T (wps)) they were wearing. A control unit established a sinusoidal change in T (wps), such that it varied from 27 to 42A degrees C. The subjects could alter the direction of the change of T (wps), when they perceived it as thermally uncomfortable. The magnitude of the oscillations towards the end of the trial was assumed to represent the upper and lower boundaries of the thermal comfort zone. The cutaneous threshold for detecting cold stimulus decreased (P < 0.05) from 1.6 (1.0)A degrees C on day 1 to 1.0 (0.3)A degrees C on day 22. No effect was observed on the ability to detect warm stimuli or on the regulated T (wps). We conclude that although cold sensitivity increased after bed rest, it was not of sufficient magnitude to cause any alteration in behavioural thermoregulatory responses.

  • 2275.
    Yu, Sicong
    et al.
    KTH, School of Technology and Health (STH).
    Hamid Muhammad, Hamed
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    Denoising of SPECT-image sinogram-data before reconstruction2014In: WMSCI 2014 - 18th World Multi-Conference on Systemics, Cybernetics and Informatics, Proceedings, 2014, Vol. 1, 202-206 p.Conference paper (Refereed)
    Abstract [en]

    Nuclear medicine images have low signal-to-noise ratio (SNR) due to several physical limitations which degrade the image quality considerably. In this study, the Gaussian filter and the patch confidence Gaussian filter (PCG) were used to improve the image quality for Single Photon Emission Computed Tomography (SPECT). The new approach applies these filtering methods on the acquired 2D-projections before reconstructing the image. The new approach was evaluated on a SPECT dataset and the performance was compared with several conventional methods presented in the literature.

  • 2276.
    Yu, Sicong
    et al.
    KTH, School of Technology and Health (STH), Health Systems Engineering.
    Hamid Muhammed, Hamed
    KTH, School of Technology and Health (STH), Health Systems Engineering.
    Comparison of Pre- and Post-Reconstruction Denoising Approaches in Positron Emission Tomography2016In: THE 1ST 2016 INTERNATIONAL CONFERENCE ON BIOMEDICAL ENGINEERING (IBIOMED 2016), IEEE, 2016, 63-68 p.Conference paper (Refereed)
    Abstract [en]

    In Positron Emission Tomography (PET), image quality is highly degraded by noise. Therefore, two main PETimage denoising approaches can be used: pre- and postreconstruction denoising. In the pre-reconstruction approach the PET sinogram is denoised before forwarding it to the image reconstruction algorithm. On the other hand, the reconstructed PET-image is denoised in the post-reconstruction approach. In this study, comparison of image quality of the resulting images of the pre- and post-reconstruction approaches is performed. In both types of approaches, the Gaussian filter, the Non-Local Means filter (NLM), the Block-Matching and 3D filter (BM3D), the K-Nearest Neighbors Filter (KNN) and the Patch Confidence K-Nearest Neighbors Filter (PCkNN) are utilized. These approaches are evaluated on a simulated PET-phantom dataset, a real-life physical thorax-phantom PET dataset as well as a reallife MicroPET-scan dataset of a mouse. The performance is measured using the Signal-to-Noise Ratio (SNR) in addition to the Contrast-to-Noise Ratio (CNR) in the resulting images.

  • 2277.
    Yu, Sicong
    et al.
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    Hamid Muhammed, Hamed
    KTH, School of Technology and Health (STH), Health Systems Engineering.
    Noise Type Evaluation in Positron Emission Tomography Images2016In: THE 1ST 2016 INTERNATIONAL CONFERENCE ON BIOMEDICAL ENGINEERING (IBIOMED 2016), IEEE, 2016, 101-106 p.Conference paper (Refereed)
    Abstract [en]

    In Positron Emission Tomography (PET), the coincident emission of gamma photon pairs constitutes the useful signals that should be detected and processed to reconstruct the desired PET images of the studied objects. However, along with the useful signal, noise is also generated and added to the detected signals that are sorted with respect to their line-ofresponse and arranged as a sinogram for each two-dimensional slice. In this paper, the type and properties of noise in PET sinogram data will be evaluated. Furthermore, the effect of the used linear and non-linear image denoising and reconstruction procedures on the type of noise will be analyzed. For this purpose, the Gaussian filter, the Median filter, the Patch Confidence k-Nearest Neighbor filter (PCkNN) and the Block Matching 3D filter (BM3D) were used to denoise PET image data, as well as the maximum likelihood expectation maximization algorithm (MLEM) and the Filtered Back Projection algorithm (FBP) to reconstruct the PET images.

  • 2278.
    Yu, Sicong
    et al.
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    Hamid Muhammed, Hamed
    KTH, School of Technology and Health (STH), Health Systems Engineering, Systems Safety and Management.
    PET image improvement using the Patch Confidence K-Nearest Neighbors Filter2014Conference paper (Refereed)
    Abstract [en]

    In Positron Emission Tomography (PET), the resulted images are highly deteriorated by noise. In this study, we propose a new denoising framework using the Patch Confidence K-Nearest Neighbors Filter (PCKNN) to reduce noise in the sinogram before forwarding it to the reconstruction procedure. This method has been evaluated on a simulated PET image of a phantom, and the performance has been compared with several conventional methods in the literature. The results have shown that the PET image quality can be substantially improved in term of increased signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR

  • 2279.
    Yusuf Isse, Muna
    et al.
    KTH, School of Technology and Health (STH).
    Tahar Aissa, Safia
    KTH, School of Technology and Health (STH).
    Ventilering av koldioxid ur kardiotomi-reservoar2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    During heart surgeries it is necessary to direct the blood away from the heart and connect the patient to an extra corporeal circulation (ECC) with an associated reservoir (cardiotomy-reservoir). In the open wound a continuous flow of carbon dioxide is insufflated. This is to de-air the wound so that no air enters the heart and large vessels during surgery. An exchange of gases occurs between the tissue of the wound and the applied carbon dioxide. Throughout the surgery the wound will bleed and that blood will be evacuated in to the cardiotomy-reservoir. This can increase the total carbon dioxide level of the patient.

    The subject that was studied in this report was how to decrease the carbon dioxide levels in the blood. The method used was to fill the cardiotomy-reservoir with chosen volumes of water and simultaneously insufflate carbon dioxide and air. This was to measure the effectiveness of the evacuation of carbon dioxide. The results were that, despite water levels and carbon dioxide supply, one was able to ventilate the reservoir. The conclusion is that the higher air supply that is used the better ventilation will be achieved.

  • 2280. Zahid, W.
    et al.
    Johnson, Jonas
    KTH, School of Technology and Health (STH), Medical Engineering.
    Westholm, C.
    Eek, C.
    Skulstad, R.
    Fosse, E.
    Winter, Reider
    Edvardsen, T.
    Mitral annular excursion in patients with suspected non-ST-elevation acute coronary syndrome can identify coronary occlusion and predict mortality2012In: European Heart Journal, ISSN 0195-668X, E-ISSN 1522-9645, Vol. 33, 912-912 p.Article in journal (Other academic)
  • 2281. Zahid, Wasim
    et al.
    Johnson, Jonas
    KTH, School of Technology and Health (STH), Medical Engineering.
    Westholm, Carl
    Eek, Christian H.
    Haugaa, Kristina H.
    Smedsrud, Marit Kristine
    Skulstad, Helge
    Fosse, Erik
    Winter, Reidar
    KTH, School of Technology and Health (STH), Medical Engineering.
    Edvardsen, Thor
    Mitral Annular Displacement by Doppler Tissue Imaging May Identify Coronary Occlusion and Predict Mortality in Patients with Non-ST-Elevation Myocardial Infarction2013In: Journal of the American Society of Echocardiography, ISSN 0894-7317, E-ISSN 1097-6795, Vol. 26, no 8, 875-884 p.Article in journal (Refereed)
    Abstract [en]

    Background: Mitral annular displacement (MAD) is a simple marker of left ventricular (LV) systolic function. The aim of this study was to test the hypothesis that MAD can distinguish patients with non-ST-segment elevation myocardial infarctions (NSTEMIs) from those with significant coronary artery disease without infarctions, identify coronary occlusion, and predict mortality in patients with NSTEMIs. MAD was compared with established indices of LV function. Methods: In this retrospective study, 167 patients with confirmed NSTEMIs were included at two Scandinavian centers. Forty patients with significant coronary artery disease but without myocardial infarctions were included as controls. Doppler tissue imaging was performed at the mitral level of the left ventricle in the three apical planes, and velocities were integrated over time to acquire MAD. LV ejection fraction, global longitudinal strain (GLS), and wall motion score index were assessed according to guidelines. Results: MAD and GLS could accurately distinguish patients with NSTEMIs from controls. During 48.6 +/- 12.1 months of follow-up, 22 of 167 died(13%). MAD, LV ejection fraction, and GLS were reduced and wall motion score index was increased among those who died compared with those who survived (P<.001, P<.001, P<.001, and P=.02, respectively). Multivariate Cox proportional-hazards analyses revealed that MAD was an independent predictor of death (hazard ratio, 1.36; 95% confidence interval, 1.07-1.73; P=.01). MAD and GLS were reduced and wall motion score index was increased in patients with coronary artery occlusion compared with those without occlusion (P=.006, P=.001, and P=.02), while LV ejection fraction did not differ (P=.20). Conclusions: MAD accurately identified patients with NSTEMIs, predicted mortality, and identified coronary occlusion in patients with NSTEMIs.

  • 2282. Zahnd, G.
    et al.
    Larsson, Matilda
    KTH, School of Technology and Health (STH), Medical Engineering.
    Gao, H.
    Serusclat, A.
    Vray, D.
    D'Hooge, J.
    A novel method to generete synthetic ultrasound data of the carotid artery based on in vivo observation as a tool to validate algorithm accuracy2012In: 2012 IEEE International Ultrasonics Symposium (IUS), 2012, 1674-1677 p.Conference paper (Refereed)
    Abstract [en]

    Ultrasound imaging represents a well designed modality to estimate the motion of biological tissues in vivo, from which relevant clinical information can be assessed. However, the lack of ground truth constitutes a challenging issue when it comes to evaluate the accuracy of computerized methods. Indeed, quantification of the reliability of experimental results often involves manual or visual human operations, which may introduce subjectivity and variability. Nonetheless, numerical simulation of the imaged tissues allow a comparison with a known reference. For this purpose, we propose in this work a realistic kinematic multi-layer model of the common carotid artery. A set of 10 models was generated by randomly positioning scatterers, on which intensity, specular reflection, and bi-dimensional motion over the duration of one cardiac cycle were applied. Two computerized methods, namely a block-matching method and a segmentation method, were also applied on our model using identical parameter settings as those used for in vivo clinical data, in the objective to assess their accuracy. The tracking errors were 42 ± 40 μm and 12 ± 10 μm in the longitudinal and radial directions, respectively. The segmentation errors were 28±18 μm for the lumen diameter, and 15±10 μm for the intima-media thickness. We conclude from these results that our model can constitute a reliable method to quantify the accuracy of computerized algorithms.

  • 2283.
    Zalet, Ayman
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Vklass datalagring: En studie om datalagring på ett kostands- och prestandaeffektivt sätt2016Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The study in this report examines data storage for the application Vklass. The problem that has been studied in this work is that the application receives and stores a big amount of files which are stored on a server locally in Stockholm where back up is made to another server on a regular basis. Today’s implemented solution for data storage endorse that the server that stores the files continues to grow each month without further structure since all the upload files is stored in the same folder which yields a more complex and less lucid storage and management for the data. This yields limitations for the performance of the application when the backup-copy needs to be restored. The owners of the application request a solu-tion that gives a more effective management of the stored data with a cost and performance effective technique. The solution that will be presented in this study should also enable stor-ing data with a more lucid and convenient structure.

    The studied methods for the solution include storing data locally and data storage in the biggest public cloud services. The investigation and analysis of the chosen methods proved that data storage in cloud services fulfilled the requirements for the identified solution as opposed to the methods for storing data locally that proved to yield deficits which would not fulfill these requirements. The deduction of this study identified Microsoft Azure Sto-rage to be the best public cloud solution for the given problem since data is stored in a per-formance and structure effective way. It was also proven that even the most expensive sto-rage solution provided by Azure Storage lowered the costs for data storage by 84 percent compared to today’s data storage solution during the first five years.

  • 2284. Zetterberg, C
    et al.
    Hemphälä, H
    Nylén, Per
    KTH, School of Technology and Health (STH), Health Systems Engineering, Ergonomics.
    Workshop in visual ergonomics2013Conference paper (Refereed)
    Abstract [en]

    Increased use of computers is common across many work sectors. Prolonged near work at a computer screen is associated with both visual discomfort and neck/shoulder discomfort and pain. Inadequate visual ergonomics at a computer workstation can also influence both visual and neck/shoulder discomfort. The new provision from the Swedish Work Environment Authority on prevention of musculoskeletal disorders includes risk assessment of occupational visual conditions. These assessments require practitioners to have knowledge of the topic, as well as experience with practical assessment tools.

    The first part of the workshop proposed here will involve a presentation of the theories underlying visual ergonomic practices and a discussion of the most important factors to assess at a computer workstation. These factors include contrast, font size, resolution, glare, reflexion, non-visual flicker, and edge sharpness. The second part of the workshop, will allow participants hands-on practice in measuring and evaluating visual ergonomics at a computer workstation.

  • 2285.
    Zhang, Chen
    et al.
    KTH, School of Technology and Health (STH), Health Systems Engineering, Health Care Logistics.
    Hanchi, Hamza
    KTH, School of Technology and Health (STH), Health Systems Engineering, Health Care Logistics.
    Meijer, Sebastiaan
    KTH, School of Technology and Health (STH), Health Systems Engineering, Health Care Logistics.
    Evaluating the Effect of Centralized Administration on Health Care Performances Using Discrete-Event Simulation2017Conference paper (Refereed)
  • 2286.
    Zhang, Chen
    et al.
    KTH, School of Technology and Health (STH), Health Systems Engineering, Health Care Logistics.
    Hanchi, Hamza
    KTH, School of Technology and Health (STH), Health Systems Engineering, Health Care Logistics.
    Meijer, Sebastiaan
    KTH, School of Technology and Health (STH), Health Systems Engineering, Health Care Logistics.
    Identifying Influential Factors of Patient Length of Stay In a Surgery Center: a Simulation Modelling Approach2017Conference paper (Refereed)
  • 2287.
    Zhang, Rui
    et al.
    University of Passau.
    Freund, Martin
    University of Passau.
    Amft, Oliver
    University of Passau.
    Cheng, Jingyuan
    DFKI.
    Zhou, Bo
    DFKI.
    Lukowicz, Paul
    DFKI.
    Seoane, Fernando
    KTH, School of Technology and Health (STH). Högskolan i Borås, Akademin för vård, arbetsliv och välfärd.
    Chabrecek, Peter
    Sefar AG.
    A generic sensor fabric for multi-modal swallowing sensing in regular upper-body shirts2016In: Proceedings of the 2016 ACM International Symposium on Wearable Computers, ACM Digital Library, 2016, 46-47 p.Conference paper (Refereed)
    Abstract [en]

    We investigate a generic fabric material as basis for resistive pressure and bio-impedance sensors and apply the fabric in a shirt collar for swallowing spotting. A pilot study confirmed the signal performance of both sensor types.

  • 2288.
    Zheng, Miaomiao
    KTH, School of Technology and Health (STH), Medical Engineering, Medical Imaging.
    Ultrasound Contrast Agents: Fabrication, size distribution and visualization2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Ultrasound contrast agents composed of micro-bubble filled with gas are introduced to increase the backscattered power from blood. Their intravenously injection results in the improved contrast in the images.

    The aim of this master thesis project is to manufacture MB suspension at varied temperature and shear forces and to inspect the size distribution and concentration of the PVA-shelled micro-bubble with standard methods according to the developed protocol. A pulser-receiver (Panametrics PR 5072) setup combined with two transducers (2.25 MHz and 5 MHz) was used to investigate the backscattered enhancement of the micro-bubble suspension.

    Images were collected with transmission optical microscope (OLYMPUS IX71) with the aid of counting chamber. The diameter and concentration of the micro-bubbles were analyzed by Image J. The pulser-receiver setup was used to test the acoustic response.

    The mean diameter of micro-bubbles was from 2.03 to 4.38 µm with a standard deviation between 0.40 and 1.12 µm and the micro-bubble concentration varied from 0.07× to 5.22× MBs/ml. The enhancement of the ultrasound backscattered power was greater than 20 dB or even reached 30 dB when the energy was increased. 

  • 2289.
    Zheng, Miaomiao
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering.
    Härmark, Johan
    KTH, School of Technology and Health (STH), Basic Science and Biomedicine, Structural Biotechnology.
    Grishenkov, Dmitry
    KTH, School of Technology and Health (STH), Medical Engineering.
    Janerot Sjöberg, Birgitta
    CLINTEC, Department of Medical Imaging and Technology, Karolinska Institute.
    Polymer-Shelled Ultrasound Contrast Agents with controlled size and polydispersity.2011In: Nanomedicine: Nanotechnology, Biology & Medicine, 2011Conference paper (Refereed)
    Abstract [en]

    Ultrasound imaging techniques can be greatly improved by the use of ultrasound contrast agents (UCAs). Gas bubbles encapsulated into biocompatible polymer shell are of particular interest of this work. Shell of the bubbles produced from Poly-Vinyl-Alcohol (PVA) offers considerable chemical versatility and stability. However, questions regarding the size and polydispersity of the microbubbles must be further investigated. The ideal UCAs should not obstruct the blood flow in pulmonary capillaries which diameter is less than 10 μm. From the technical perspective UCAs should modify the acoustic properties of a region of interest, by increasing backscattered efficiency. In order to enhance the ultrasound response UCAs should be engineered with narrow size distribution. In the present work PVA-shelled UCAs with controlled size and polydispersity is manufactured under varied parameters of the manufacturing protocol. It was observed that temperature of the surrounding atmosphere has major effect on the size of the UCAs, while polydispersity is regulated by geometry and speed of the disperser. Finally, the acoustic response of these microbubbles is tested using developed ultrasound test rig. The enhancement of the backscattered power of about 25 dB from a suspension of the microbubbles is observed at 5 MHz ultrasound frequency. Keeping in mind that in clinical practice ultrasound scatter from the blood is of about 30 dB weaker than scatter from surrounding tissue, introduction of novel PVA microbubbles will potentially improve diagnosis of the cardiovascular patients.

  • 2290.
    Zhong, Xueying
    KTH, School of Technology and Health (STH), Medical Engineering.
    Mucin preparation and assembly into new biomaterials2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Mucins, the main macromolecular constituent responsible for gel-forming property in mucus, have great potential to act as new biological hydrogel for medical applications. Click chemistry reaction is an attractive tool to be applied in both bioconjugation and material science to form covalent bonds between molecules. Herein the click chemistry reaction of tetrazine-norbornene ligation was adapted to form click mucin hydrogel using purified commercial available bovine submaxillary mucin (BSM). This study included the characterization, purification and chemical modification of commercial available BSM. The flow filtration purification was chosen after investigating the effectiveness and yields of four different purification strategies. The reactivity of tetrazine and norbornene-functionalized BSM was evident from the formation of robust mucin hydrogel within minutes after mixing the two components. 

  • 2291.
    Zhu, Lin
    KTH, School of Technology and Health (STH), Basic Science and Biomedicine, Structural Biotechnology.
    Structural studies of HDL and applications of EM on membrane proteins2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    A large number of proteins interact with biological membranes, either integrated in the membrane (PepTSo2), embedded on a membrane surface (5-lipoxygenase) or encircling a cutout of lipid bilayer (apolipoprotein1 (apoA-I). They function as transporters, receptors or biocatalysts in cellular processes like inflammation or cholesterol transport which are touched upon here. Malfunction of specific membrane proteins are the cause for several diseases or disorders.

    Knowledge of protein structure supports understanding of its mechanism of function. Here, transmission electron microscopy (TEM) was used for structure determination. To obtain structure information to high resolution for membrane proteins, normally surrounded by lipids, demands specific methods and materials for stabilization. Stabilized in detergent the structure of the bacterial transporter PepTSo2 was shown to form a tetramer even bound to substrate. However, with a protein based stabilizer, Salipro, the structure of PepTSo2 could be determined to high resolution.

    High density lipoprotein (HDL) in blood plasma, involved in the removal of cholesterol from peripheral tissues, have a central role in cardiovascular function, metabolic syndrome and diabetes.

    The HDL-particle is composed of two copies of ApoA1 and around hundred lipid molecules. From TEM data, for the first time the clearly discoidal shape could be shown by 3-dimendional reconstructions. These were used for modelling the ApoA1 protein dimer by a "biased fitting" procedure. The results indicate how ApoA1 folds around a lipid bilayer in a disc-shaped structure.

    Modified HDL called nanodiscs were here used to show the Ca2+ dependent binding of 5-lipoxygenase on the nanodisc bilayer and thereby increased production of the inflammatory mediator leukotrieneA4. Dimerization of 5-lipoxygenase inactivates these functions.

  • 2292.
    Zhu, Lin
    KTH, School of Technology and Health (STH), Basic Science and Biomedicine, Structural Biotechnology.
    Structural Studies of High Density Lipoprotein by Electron Microscopy and Flexible FittingManuscript (preprint) (Other academic)
  • 2293.
    Zhu, Lin
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Structural Biotechnology. Karolinska Institutet, Sweden.
    Petrlova, J.
    Gysbers, P.
    Hebert, Hans
    KTH, School of Technology and Health (STH), Medical Engineering, Structural Biotechnology. Karolinska Institutet, Sweden.
    Wallin, S.
    Jegerschöld, Caroline
    KTH, School of Technology and Health (STH). Karolinska Institutet, Sweden.
    Lagerstedt, J. O.
    Structures of apolipoprotein A-I in high density lipoprotein generated by electron microscopy and biased simulations2017In: Biochimica et Biophysica Acta - General Subjects, ISSN 0304-4165, E-ISSN 1872-8006, Vol. 1861, no 11, 2726-2738 p.Article in journal (Refereed)
    Abstract [en]

    Background: Apolipoprotein A-I (apoA-I) in high-density lipoprotein (HDL) is a key protein for the transport of cholesterol from the vascular wall to the liver. The formation and structure of nascent HDL, composed of apoA-I and phospholipids, is critical to this process. Methods: The HDL was assembled in vitro from apoA-I, cholesterol and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) at a 1:4:50 molar ratio. The structure of HDL was investigated in vitreous samples, frozen at cryogenic temperatures, as well as in negatively stained samples by transmission electron microscopy. Low resolution electron density maps were next used as restraints in biased Monte Carlo simulations of apolipoprotein A-I dimers, with an initial structure derived from atomic resolution X-ray structures. Results: Two final apoA-I structure models for the full-length structure of apoA-I dimer in the lipid bound conformation were generated, showing a nearly circular, flat particle with an uneven particle thickness. Conclusions: The generated structures provide evidence for the discoidal, antiparallel arrangement of apoA-I in nascent HDL, and propose two preferred conformations of the flexible N-termini.

  • 2294. Zhuang, C.
    et al.
    Marquez, Juan C.
    KTH, School of Technology and Health (STH), Medical Engineering, Medical sensors, signals and systems. Shanghai Jiao Tong University, China.
    Qu, H. E.
    He, X.
    Lan, N.
    A neuromuscular electrical stimulation strategy based on muscle synergy for stroke rehabilitation2015In: International IEEE/EMBS Conference on Neural Engineering, NER, IEEE Computer Society, 2015, 816-819 p.Conference paper (Refereed)
    Abstract [en]

    Recent experiments have suggested that the central nervous system (CNS) makes use of muscle synergies as a neural strategy to simplify the control of a variety of movements by using a single pattern of neural command signal. This nature of muscle coordination could have great significance in the treatment and rehabilitation of upper limb impairments for hemiparetic patients post stroke. The use of neuromuscular electrical stimulation (NMES) for neural prosthetics or therapeutic applications has been demonstrated as a promising clinical intervention for stroke patients to recover motor function of the upper extremity. However, the existing NMES systems do not provide control methods for the patient to achieve an individualized and functional rehabilitation training. In this research work, muscle synergies from the flexionextension elbow antagonistic muscles were studied. Using motion information and EMG signals, muscle synergies were extracted using non-negative matrix factorization (NMF) method. Reconstructed signals obtained from the muscle synergies were then applied to the virtual arm (VA) model to test a synergy based NMES strategy. Results show close resemblance to the original elbow trajectory of normal movements and thus the feasibility to control movements in stroke patients for rehabilitation.

  • 2295.
    Zika-Wiktorsson, Annika
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Sundström, Per
    KTH, School of Technology and Health (STH).
    Engwall, Mats
    VINNOVA, Swedish Governmental Agency for Innovation Systems.
    Project Overload: An Exploratory Study of Work and Management in Multi-Project Settings2006In: International Journal of Project Management, ISSN 0263-7863, E-ISSN 1873-4634, Vol. 24, no 5, 385-394 p.Article in journal (Refereed)
    Abstract [en]

    This study investigates psychosocial aspects of work in multi-project settings and how project members and project managers at operational level perceive their work situation. Work in a multi-project setting entails a complicated situation characterized by tight schedules, multi-tasking, increased coordination expenditures, and a large amount of set-up time when alternating between tasks. The study addresses the issue of project overload, a construct that in this study reflects perceived fragmentation, disruption and inefficiency, caused by switching between assignments for separate but simultaneous projects. An explorative approach was adopted for the study, and new models were created and investigated. The primary source of data was a web-based questionnaire. The questionnaire was administered to project co-workers (n = 392) in nine companies in Sweden (response rate: 81%). The companies represented manufacturing, pharmaceutical and construction industries, and all occupied a leading position on their respective markets. The results show that almost one-third of the respondents were under perceived project overload, and that 21% (p ≤ .001) of the variance on this variable could be explained by four factors. In order of magnitude, these factors were: (1) lack of opportunities for recuperation, (2) inadequate routines, (3) scarce time resources, and (4) a large number of simultaneous projects. Further, the study indicated that there are associations between high level of project overload and (a) high levels of psychological stress reactions, (b) decreased competence development, and (c) deviations from time schedules.

  • 2296.
    Zomer, Lara-Britt
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science.
    Daamen, Winnie
    TU Delft.
    Meijer, Sebastiaan
    KTH, School of Technology and Health (STH), Health Systems Engineering, Health Care Logistics.
    Hoogendoorn, Serge
    TU Delft.
    Managing Crowds: The Possibilities and Limitations of Crowd Information During Urban Mass Events2015Conference paper (Refereed)
    Abstract [en]

    Thischapter,basedonamixedmethodresearchapproach,offersinsights into possibilities and limitations of using ICT measures for crowd management and distribution during urban mass events (UMEs). Based on literature, practical applications and analyses of research results, we propose crowd management should consider characteristics of both crowds and UMEs to increase information effectiveness. In relation to urban planning, results show that possibilities to influence a crowd’s behavior depend on available (and known) choice sets offered in various locations, while distances towards locations across city centers appear less important. Limitations appear to be related to scarce knowledge on what drives crowd members to adapt or adhere to their activity choice behavior. Such insights are essential for smart cities striving for an optimal use of infrastructural capacity, as both the ambiguous effects of ICT measures, as well as a crowd’s self-organizing capacity should be taken into account for delaying, solving and preventing dis- ruptions of pedestrian flows in city centers. 

  • 2297. Zomer, Lara-Britt
    et al.
    Moustaid, Elhabib
    KTH, School of Technology and Health (STH), Health Systems Engineering, Health Care Logistics.
    Meijer, Sebastiaan
    KTH, School of Technology and Health (STH), Health Systems Engineering, Health Care Logistics.
    A Meta-Model for Including Social Behavior and Data into Simulation in the Smart City Context2015In: Proceedings of the 2015 Winter Simulation Conference / [ed] L. Yilmaz, W. K. V. Chan, I. Moon, T. M. K. Roeder, C. Macal, and M. D. Rossetti, 2015Conference paper (Refereed)
    Abstract [en]

    mart city management can be regarded to bridge different realms of thinking about cities, i.e., 1) the city as complex-adaptive system, 2) socio-technical operational control center and 3) multi-actor policy-making. Underpinned by different world views and theoretical bodies, integration of the three realms puts forward new demands on simulation approaches and challenges current knowledge and available technology regarding integration of sub-models across different systems. In order to support urban transportation management, a holistic approach is needed that semantically connects the three realms by incorporation of human behavior and knowledge. Combining research on knowledge management and computer science, this paper presents a novel meta-framework as socio-technical hybrid simulation language to generalize integration of simulations, gaming and data for modeling urban transportation.

  • 2298. Zou, H.
    et al.
    Kleiven, Svein
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Schmiedelera, J. P.
    The effect of brain mass and moment of inertia on relative brain-skull displacement during low-severity impacts2007In: International Journal of Crashworthiness, ISSN 1358-8265, E-ISSN 1754-2111, Vol. 12, no 4, 341-353 p.Article in journal (Refereed)
    Abstract [en]

    Traumatic brain injury is the leading cause of death in automobile crashes. The sensitivity of human brain injury prediction to small parameter changes is a critical element of both experimental and mathematical work yet to be adequately investigated. This work proposes a new analytical human brain injury model to determine the parameters to which injury prediction is most sensitive. The trajectory sensitivity analysis explicitly indicates that injury prediction is most sensitive to brain mass moment of inertia, followed by brain mass. A number of finite element (FE) simulations were executed with various brain sizes. The maximum relative brain motions decrease with decreased brain size, and they are very close in the FE and analytical models. We conclude that brain mass moment of inertia, primarily, and brain mass, secondarily, should be varied in focused experimental and FE modeling work to ensure that conclusions are not drawn from individual data points at which injury predictions are highly sensitive to small parameter changes.

  • 2299.
    Zou, Hong
    et al.
    Department of Mechanical Engineering, The Ohio State University.
    Kleiven, Svein
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Schmiedeler, James P.
    Department of Mechanical Engineering, The Ohio State University.
    The Effect of Brain Mass and Moment of Inertia on Relative Brain-Skull Displacement in Low-Severity Impacts2006Conference paper (Refereed)
  • 2300.
    Åberg, Jenny
    KTH, School of Technology and Health (STH), Health Systems Engineering.
    Möjligheter och hinder för det förebyggande arbetsmiljöarbetet: En intervjustudie med en enhet på Feelgood Företagshälsa och två av deras kundföretag inom byggbranschen.2015Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Background: The occupational health services (OHS) in Sweden is provided as an impartial expert advice to client companies and shall identify and explain the relationship between work, organization, productivity and health. In general, client companies use the occupational health services particularly for reactive services, when illness has already occured in the company. Construction workers staying constantly in a hazardous environment and are exposed to heavy lifting, monotonous movements and bad working positions. It is therefore important to examine how occupational health can contribute to the preventive work environment for client companies to meet the challenges of the construction work.Aim: The aim of the study was to investigate the opportunities and barriers that exist to the preventive work of occupational health services.Method: A literature review and an interview study was conducted in spring 2013. Scientific papers and other documents were obtained through databases available through the libraries at the Royal Institute of Technology, University of Gothenburg and Halmstad University. Ten individual semi-structural interviews were carried out with a safety engineer and an account manager at a Feelgood unit, as well as with supervisors, safety representatives and with people who had an HR and working position on two of Feelgoods client companies in the construction industry.Results: The analysis revealed eight themes that represented opportunities and barriers to preventive work environment: consultative approach, systematic work environment management, workplaces visits, competence, marketing and communication, management, lack of coordination between professions in occupational health services and customer agreement.Conclusion: The occupational health service needs to take greater responsibility in preventive work environment and challenging client companies to advise them in good working solutions. Occupational health services also needs to be better at marketing their business to client companies to know what they can use OHS for. Feelgood are professional and have high competence in the individual conversations but can improve their professional skills at organizational level. The client companies demand field visits and they saw that OHS has a role in performing technical measurements and help in the process of job rotation. Preventive health services should be written into the agreement in order to be utilized to a greater extent.

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