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  • 1.
    Afroze, Tonima
    et al.
    KTH, School of Technology and Health (STH).
    Rosén Gardell, Moa
    KTH, School of Technology and Health (STH).
    Algorithm Construction for Efficient Scheduling of Advanced Health Care at Home2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

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

  • 2.
    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.

  • 3.
    Bassan, Gioia
    KTH, School of Technology and Health (STH).
    Dual-Probe Shear Wave Elastography in a Transversely Isotropic Phantom2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Shear Wave Elastography (SWE) is an ultrasound based technique which is able to measure tissue stiffness through the speed of induced shear waves. Tissue stiffness is often related to pathological conditions and detecting mechanical changes can help the recognition of potential diseases. The clinical use of SWE is limited to isotropic tissue due to the difficulty in assessing a theoretical model for more complex tissue and this project therefore aimed to evaluate the possibility of obtaining a full mechanical characterization of a transversely isotropic (TI) phantom with dual-probe SWE. A TI hydrogel phantom was developed and mechanical tests were performed to verify its anisotropy and determine the elastic moduli in both the perpendicular and longitudinal directions. Shear moduli were estimated using conventional and dual-probe SWE comparing the results to theoretical pure-transverse (PT) and quasi-transverse (QT) wave propagation modes. Both mechanical and SWE tests showed that the phantoms were transversely isotropic ET/EL=0.81. Moreover, multiple wave propagation modes calculated with dual-probe SWE showed a good agreement with the theoretical curves and indicated the possibility of measuring all the elasticity constants needed to fully characterize an incompressible, TI tissue with dual-probe SWE.

  • 4.
    Bährecke, Niklas
    KTH, School of Technology and Health (STH).
    Automatic Classification and Visualisation of Gas from Infrared Video Data2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Optical gas imaging denotes the visualisation of gases by means of an infrared camera, which allows operators to quickly, easily, and safely scan a large area and therefore plays a major role in the early detection and repair of gas leaks in various environments within the petrochemical industry such as processing plants and pipelines, but also in production facilities and hospitals. Thereby they help to avert damage to the environment as well as to health and safety of workers or inhabitants of nearby residential areas. The current generation of thermal gas cameras employs a so-called high-sensitivity mode, based on frame differencing, to increase the visibility of gas plumes. However, this method often results in image degradation through loss of orientation, distortion, and additional noise. Taking the increased prevalence and sinking costs for IR gas cameras – entailing an increased number of inexperienced users – into consideration, a more intuitive and user-friendly system to visualise gas constitutes a useful feature for the next generation of IR gas cameras. A system that retains the original infrared video images and highlights the gas cloud, providing the user with a clear and distinct visualisation of gas on the camera’s display, would be one example for such a visualisation system. This thesis discusses the design of such an automatic gas detection and visualisation framework based on machine learning and computer vision methods, where moving objects in video images are detected and classified as gas or non-gas based on appearance and spatiotemporal features. The main goal was to conduct a proof-of-concept study of this method, which included gathering examples for training a classifier as well as implementing the framework and evaluating several feature descriptors – both static and dynamic ones – with regard to their classification performance in gas detection in video images. Depending on the application scenario, the methods evaluated in this study are capable of reliably detecting gas.

  • 5.
    Carlsson, Tor
    KTH, School of Technology and Health (STH).
    Individualized Motion Monitoring by Wearable Sensor: Pre-impact fall detection using SVM and sensor fusion2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Among the elderly, falling represents a major threat to the individual health, and is considered as a major source of morbidity and mortality. In Sweden alone, three elderly are lost each day in accidents related to falling. The elderly who survive the fall are likely to be suffering from decreased quality of life. As the percentage of elderly increase in the population worldwide, the need for preventive methods and tools will grow drastically in order to deal with the increasing health-care costs. This report is the result of a conceptual study where an algorithm for individualized motion monitoring and pre-impact fall detection is developed. The algorithm learns the normal state of the wearer in order to detect anomalous events such as a fall. Furthermore, this report presents the requirements and issues related to the implementation of such a system. The result of the study is presented as a comparison between the individualized system and a more generalized fall detection system. The conclusion is that the presented type of algorithm is capable of learning the user behaviour and is able to detect a fall before the user impacts the ground, with a mean lead time of 301ms.

  • 6.
    Di Sopra, Lorenzo
    KTH, School of Technology and Health (STH).
    Geometric Misalignment Calibration and Detector Lag Effect Artifact Correction in a Cone-Beam Flat Panel micro-CT System for Small Animal Imaging2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The cone-beam flat panel micro-CT is a high definition imaging system. It acquires projections of an object or animal to reconstruct a 3D image of its internal structure. The device is basically composed by a radiation tube and a detector panel, which are fixed to a gantry that rotates all around the test subject. The micro-CT system is affected by several imperfections and problems, that might lead to serious artifacts that deteriorate the quality of the reconstructed image. In particular, two issues have been discussed in the present work: the source-panel geometric misalignment and the detector lag effect. The first problem concerns the consequences of systems where the different elements are not perfectly aligned to each other. The second issue regards the residual signal, left in the detector's sensor after a projection acquisition, which affects the following frames with ghost images. Both these arguments have been investigated to describe their characteristics and behaviour in a typical acquisition protocol. Then two correction methods have been presented and tested on a real micro-CT device to verify their effectiveness in the artifacts compensation. In the end, a comparison between images before and after the corrections is provided and future prospects are discussed.

  • 7.
    Elmasoudi, Solayman
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Finite element modelling of a pedestrian impact dummy2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 8.
    Jönsson, Maria
    et al.
    KTH, School of Technology and Health (STH).
    Boije, Malin
    KTH, School of Technology and Health (STH).
    Biomechanical Simulations of a Flywheel Exercise Device in Microgravity2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Bone loss and muscle atrophy are two main physiological conditions affecting astronauts while being in space. In order to counteract the effects, at least two hours of aerobic and resistant countermeasure exercise is scheduled into their working day, seven days a week. Yoyo Technology AB has developed a resistance exercise device based on the flywheel principle, providing a load independent of gravity. However, there is no biomechanical research done on the efficiency of the device in microgravity, from a human movement point of view using simulation software.

    The aim of this thesis was to evaluate the effects of performing a leg press on the flywheel exercise device in a microgravity environment. Simulations of performing a flywheel leg press in earth gravity, microgravity and performing a conventional squat were done. The evaluated parameters were reaction forces, joint angles, joint moments, joint powers and muscle recruitment in the lower extremities. The simulations were done using a biomechanical simulation software based on a motion capture data collection.

    From the results two conclusions were proposed. Performing a flywheel leg press in microgravity environment or on earth provides at least as much peak moment as a body weighted squat performed on earth. Furthermore, performing a flywheel leg press in microgravity will induce a higher activity level among hip extensors and knee flexors compared to performing a flywheel leg press on earth. 

  • 9.
    Lef, Catherine
    et al.
    KTH, School of Technology and Health (STH).
    Dolange, Guillaume
    KTH, School of Technology and Health (STH).
    Understanding Lower Leg Injury in Offset Frontal Crash: A Multivariate Analysis2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Lower leg injury is an important issue in frontal car crash. Although safety in cars has been

    improved by developments such as seat belts and airbags, lower leg injuries have not been

    reduced. These injuries are not life threatening but can result in long term disability and cost a

    lot to society. This study focused on the passenger occupant in offset frontal crashes and aimed

    at understanding and finding ways to reduce the injury criteria for the lower leg: tibia index. A

    finite element model was simplified to introduce parameters which influence on tibia index was

    investigated with a multivariate analysis. The model simplification consisted in removing

    irrelevant parts and replacing other parts by simple foam blocks. More than 1300 simulations

    were run with different parameter values. The results were then analysed by calculating

    correlations and effects of the parameters on tibia index. It was concluded that the presence of

    a knee bolster decreased tibia index. The results also showed a decrease of tibia index when the

    toe pan was angled towards the legs of the passenger. Moreover, a correlation between tibia

    index and the movement of the feet during the crash was found. It was concluded that restrained

    lower legs also presented decreased tibia indices compared to unrestrained ones. Most of the

    results proved to be also valid on the initial, unsimplified finite element model.

  • 10.
    Lillro, Ejla
    KTH, School of Technology and Health (STH).
    Image Sensor System for Detection of Bacteria and Antibiotic Resistance2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Antibiotic resistance is now a recognized problem in global health. In attempts to find solutions to detect bacteria causing antibiotic resistance we turn to technological solutions that are miniaturized, portable and cheap. The current diagnostic procedures cannot provide correct information outside laboratory settings, at the point-of-care, within necessary time. This has led to ineffective treatment of urinary tract infections causing recurrent infections and multi-drug resistant bacteria to spread. The bacteria genes show which antibiotic that is required to eliminate disease and spread of resistance. Hence, the solution would be to perform nucleic acid testing at the point-of-care. By using new DNA amplification methods it is possible to miniaturize the diagnostic test to a so-called Lab-on-a-chip. These solutions would enable sample-in-results-out capability of the system at the point-of-care. For this to work one of the most important factors is fluorescent signal read-out from DNA amplification products.

    In this project the design parameters of such a read-out device was investigated with focus on image sensor sensitivity and device integration. During the project it was found that a low-cost commercial image sensor could be used to record images of a (3.76 x 2.74 mm2) micro well array of nanoliter sized PCR chambers. Different imaging artifacts appearing during sample partitioning were observed, distance dependency between sensor surface well array was investigate, and finally the image sensor function was compared to a fluorescent microscope.

  • 11.
    Nilsson, Karin
    KTH, School of Technology and Health (STH).
    Att fånga det oförutsägbara: Utveckling av serviceprocessen vid Siemens Healthcare2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Siemens Healthcare provides imaging and laboratory diagnostics and IT-solutions for operators within healthcare. In order to provide their customers with good service, Siemens Healthcare have a specific service process and guidelines that describe the process step by step - from the time an errand is created until it is completed. The errands include services such as unscheduled errands, predetermined maintenances, updates, and installations and upgrades. The service process includes different professional roles, areas and departments performing various tasks in the handling of an errand, and multiple professional roles that provide support within the service process. In 2014 an internal audit was conducted at Siemens Healthcare in Sweden which showed that they did not follow the exact guidelines for the processes and the documentation within the service process. The goal with this thesis was to analyze and map supports and barriers for the staff to be able to follow the guidelines, and give recommendations on how compliance to the guidelines can be improved.

    To achieve this goal, 16 interviews were conducted with all the professionals who work within the service process or work as a support. Two different types of interviews were conducted. Two observations were also performed of two different professional roles. The interviews were then analyzed using a qualitative content analysis and processed to provide a probability and work effort chart that showed subjects of interest. As a part of the method, an improvement event has also been performed to start the improvement work together with the employees and the management.

    The result showed that there are several supportive and prohibitive factors for the staff to be able to follow the guidelines. The factors include the formulation and implementation of the guidelines, and that there were a vague and variable and unclear division of work. The factors also included education and support within the IT systems, and that there were a more or less lack of communication and understanding between some departments and professional roles.

    The recommendations is to rephrase the guidelines in consultation with the employees, standardize and describe the work routines, look over the system support and the system functions, and introduce cross-functional meetings and groups between different professional roles and departments. These recommendations could not only improve the compliance with the guidelines, but the organization and its employees could also continuously develop.

  • 12.
    Nordbrøden, Mats
    KTH, School of Technology and Health (STH).
    Optimization of Magnetic Resonance Diffusion Tensor Imaging for Visualization and Quantification of Periprostatic Nerve Fibers2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Prostatectomy, surgical resection of the whole prostate is a common treatment for high- risk prostate cancer. Common side effects include long-time urinary and or erectile dysfunction due to damage inflicted to periprostatic nerves. The aim of this study was to identify an optimal magnetic resonance diffusion tensor imaging protocol for visualization and quantification of these nerves, as pre-surgery visualization may help nerve-sparing surgery. Both scanner filter, parameters for accelerated scan techniques, diffusion-related acquisition parameters and post- processing tractography parameters were investigated. Seven healthy volunteers were scanned with a state-of-art 3 T MRI scanner with varying protocol parameters. Diffusion data were processed and analysed using Matlab and Explore DTI. The resulting protocol recommendation included a normalized scanner filter, a parallel imaging acceleration factor of 2, partial Fourier sampling of 6/8, a right-left phase encoding direction, a b-value of 600 s/mm2, monopolar gradient polarity with applied eddy current correction, four acquisitions of 12 diffusion- sensitizing gradient directions, and a reverse phase encoding approach for correction of geometrical image distortions induced by static field inhomogeneity. For post-processing tractography, the recommended parameters were a lower limit for fractional anisotropy of 0.05, a minimum tract length of 3 centimetres and a maximum turning angle between voxels of 60 degrees. The limited parameter range that was tested and the low number of volunteers can be regarded as limitations to this study. Future work should address these issues. Furthermore, feasibility of periprostatic nerve tracking with the optimized protocol should be tested in a patient study. 

  • 13.
    Okan, Julianne
    KTH, School of Technology and Health (STH).
    Development of a Fall-Injury Reducing Flooring System in Geriatric Care: with focus on improving the models used in the biomechanical simulations and evaluating the first test area2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Fall accidents are the type of accident in Sweden that cause most deaths, the largest number of hospitalizations, and most visits to the emergency room. The elderly are overrepresented in the statistics and with the aging population the costs are increasing. One way of reducing both the personal suffering and the cost to society is to introduce safety flooring. Svein Kleiven and Hans von Holst, professors at the department of Neuronics at KTH, have developed a new type of flooring system aimed to reduce fall related injuries. A first test area has been installed at a care facility and the Technical Research Institute of Sweden, SP, has conducted drop tests on nine different prototypes and found a reduction in impact force between 60- 75 % compared to a wooden flooring.

    The goals of this Master’s thesis were to conduct material testing to enable a better validation of the finite element (FE) model of the flooring system, validate a FE human body model for a hip impact and conduct fall simulations. The last goal was to evaluate the test area of the flooring system regarding effect on balance and work environment.

    Tensile tests were conducted to increase the knowledge regarding the different rubber mixtures and surface floors used in prototypes of the flooring system. The human body model had to be modified in regards to material models and anatomy of the hip joint before validated. Two fall simulations were conducted, however with low confidence in the results due to the lack of expected response in the model of the flooring system. A walking test was conducted to investigate if the flooring system affected the balance for the elderly and a questionnaire was created to get subjective ratings from the members of staff at the care facility. The results indicate no clear effect on balance and the subjective ratings shows the importance of also consider the work environment before installing the flooring system.

    More work remains in developing the flooring system; however this Master’s thesis has increased the understanding of the flooring system, both in regards to material properties and influence on the daily life at the care facility. This thesis also developed a more realistic human model, to be used in further hip impact simulations. 

  • 14.
    Olsson, Hanna
    KTH, School of Technology and Health (STH).
    Smartphone-based Colorimetric Diagnosis: DEVELOPMENT OF A METHOD FOR AUTOMATIC COMPENSATION OF IMPACT OF LIGHT SETTING2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    During the last years many mobile health applications have emerged on the market. Most of these collect and compiles physical data that can be followed over time. Now the next generation of health care applications are on their way. With an increasing capacity and high quality sensors, smartphones have the potential to be used as diagnostic tools.

    Calmark Sweden AB is a company that has developed a smartphone based diagnostic platform for analysis of colorimetric assays integrated on a disposable plastic chip. Their first product, the hilda Neo system is a Point of care test (POCT) for semi quantitative measurement of the biomarker Lac- tate dehydrogenase (LDH). The system consists of a disposable colorimetric LDH test with inte- grated chemical assay, a separate light-box for controlled light conditions and a smartphone appli- cation for image acquisition and test analysis.

    The purpose of this Master Thesis project was to develop and evaluate a method for smartphone based semi quantitative colorimetric analysis of the hilda Neo LDH test that would work without the light-box in different light settings. The method was to be implementable as an iPhone applica- tion and should be able do correctly determine LDH activity in the four LDH ranges; 0-300, 300- 600, 600-900 and >900 units per litre (U/L). Also, the computed LDH levels among cards run with the same sample were not to have a standard deviation higher than 50 U/L.

    Two methods based on continuous measurements of the colour stimuli given from the assay site were developed. In both methods, measurements were made by using the iPhone camera for taking an image series following the colour development of the assay over time. The image series was then processed in MATLAB and the LDH level was computed in two different ways.

    None of the two proposed methods did reach the stated objectives. Neither of the methods gave the correct LDH interval in all evaluation cards and the computed LDH levels had a larger standard deviation then aimed for. However the results indicate that the variation in light settings is not the only factor for the unreached objectives. It is believed that with further studies of the colour proper- ties of the hilda Neo assay and with the continuing development of smartphone technology, it is possible to find a method for smartphone-based colorimetric analysis without having to control the light setting. 

  • 15.
    Papastathis, Ioannis
    KTH, School of Technology and Health (STH).
    Intention Detection and Arm Kinematic Control in Soft Robotic Medical Assistive Device2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Aging in humans is often associated with reduced muscle strength and difficulty in elevating the arm and sustaining it at a certain position. The aim of this master thesis is to propose a number of technical solutions integrated into a complete electronic system which can be used to support the user's muscle capacity and partially resist gravitational load. An electronic system consisting of sensors, a control unit and an actuator has been developed. The system is able to detect the user's motion intention based on an angle detection algorithm and perform kinematic control over the user's arm by adjusting the level of support at different degrees of elevation. A force control algorithm has been developed for controlling the actuating mechanism, providing the user with a natural and intuitive support during arm elevation. The implemented system is a first step towards the development of a medical assistive device for the elderly or patients with reduced muscle strength allowing them to independently perform a number of personal activities of daily life where active participation of the upper limb is required.

  • 16.
    Prabhakaran, Gokulraj
    KTH, School of Technology and Health (STH), Medical Engineering, Medical Imaging.
    Imaging Memory Encoding in Mild Cognitive Impairment (MCI) using fMRI2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 17.
    Selvaratnam, Thevapriya
    KTH, School of Technology and Health (STH).
    Optimization and characterization of a centrally functionalized quartz crystal microbalance sensor surface for Norovirus detection: Optimering och karakterisering av en centralt funktionaliserad kvartskristall mikrovåg sensoryta för norovirus detektion2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this study a biosensor based on real time quartz crystal microbalance (QCM) monitoring is optimized and characterized for the application in the Norosensor. This biosensor is aimed to recognise, capture and amplify Norovirus (NoV). In an initial step a simplified bioassay was developed that focuses on the latter parts of the assay which consists of DNA-guided probing and amplification of the captured virus and includes the development of an amplification model assay directly to the functionalised crystal surface. A padlock probe with matching sequence to the conjugated oligonucleotide on the quartz crystal surface is used as target in the model assay. Although a number of studies have been carried out based on padlock probe ligation and rolling circle amplification (RCA) based QCM sensing, these studies utilize the entire crystal surface to capture and amplify the biomolecule. In this research work the QCM monitoring is explored on a centrally functionalised electrode surface through conjugation only at the centre of the electrode for increased mass sensitivity. Thus, allowing capture and amplification of the padlock probe only at the centre of the quartz crystal.

    A 14mm diameter, thermoncompensated AT-cut, nonpolished quartz crystal with a 10mm diameter gold surface coating acting as electrode was utilized for QCM measurements. The detection system is based on mass binding and amplification on the QCM to produce a negative frequency shift in the fundamental frequency of the vibrating quartz crystal. The amplification products were additionally fluorescently labelled and fluorescent microscopy images were also obtained at the end of every experiment to verify the presence or absence of DNA capture and amplification.

    Experimental findings show that the current flow chamber with a 15ul capacity is able to detect a specific padlock probe concentration of 1nM on a conjugated region of ~2.5mm diameter. RCA amplified the mass with an average frequency shift of -80Hz in 60mins RCA incubation time. Further, the specificity and sensitivity of the QCM system was explored.

    However, the system has limitations where sensor binding of reaction proteins, such as DNA ligase and BSA, to some extent is observed. The storage stability of the functionalized self-assembled monolayer (SAM) on the QCM is also observed to deteriorate and thus, is of concern. Nevertheless the combination of RCA based amplification with QCM real-time monitoring has the potential for rapid and simple, low cost detection of the Norovirus.

  • 18.
    Sherifova, Selda
    KTH, School of Technology and Health (STH).
    Modeling the Propagation of Aortic Dissection2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Aortic dissection is a diseased condition of the aorta in which there is an initial tear to the intimal layer propagating in the radial direction initially then causing delamination of the arterial layers creating a false lumen. It is estimated to effect 30 individuals in one million per year. The dissection is fatal when it ruptures, and 90 % of the patients die within three months if not diagnosed.

    This study presents the first steps towards modeling the propagation of aortic dissection. The aorta was treated as a three-layered fiber-reinforced composite structure, and the Tsai-Wu failure criterion was employed to obtain the 3-D failure surface for the healthy and dissected human aortic media. To be able to obtain Tsai-Wu coefficients, uniaxial tensile tests in the axial, circumferential, and radial direction, and additionally in-plane (axial-circumferential plane) and out-of-plane shear tests in different orientations were performed on human aortic medias. To our knowledge the combination of applied tests and performingof out-of-plane shear tests on aortic tissues is novel.

    The results showed that the aortic media was the weakest in radial direction under tensile loading. Furthermore, the media was much stronger under out-of-plane shear loading than under in-plane shear loading. In order to consider influences of stress coupling between axial and circumferential directions, an optimal specimen geometry was designed for biaxial tensile testing by the help of finite element analyses. A cruciform geometry with a reduced cross-section in the biaxially loaded zone was found to fit our purposes the best. The preparation protocol to achieve this geometry is currently under investigation. For aortic tissues, all compressive strengths and some biaxial tensile strengths needed to be assumed since they are yet not possible to obtain from mechanical tests. Finally, failure surfaces described by the Tsai-Wu criterion were plotted in 2-D using the analyzed experimental data, with different assumptions in compressive and biaxial tensile strengths.

  • 19.
    Sjödahl, Sofie
    KTH, School of Technology and Health (STH).
    A Pilot Study on the Effectiveness of Heart Rate Variability Biofeedback on Healthy Subjects2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Heart Rate Variability (HRV) is a medical term describing the heart’s natural varying time difference between heartbeats (called NN-intervals). A higher HRV i.e. a larger variability between NN-intervals is connected to healthiness, and lower HRV to unhealthy states.

    Biofeedback (BF) is a method that can detect and send physiological signals back to the user on a screen. Every individual has a resonant frequency, and when breathing at this frequency, the interplay between blood pressure and respiration causes HRV to increase momentarily. HRV biofeedback aims at increasing HRV, by measuring heart rhythm and respiration to guide the user in resonant breathing.

    This thesis had the objective to investigate the effectiveness of one 20 minutes long biofeedback session with resonant frequency breathing. The hypothesis was that the time frame would be longer than two hours. It was carried out with 12 healthy volunteers, who participated in a biofeedback session with an Android application, and afterwards 5 minutes long ECG measurements were made every half hour for two hours. A control session was held with the same participants to give the trial more scientific strength.

    The result showed that a 20 min resonant breathing biofeedback session can elevate Standard Deviation of NN intervals (SDNN) significantly (p < 0.05), 2 hours after the biofeedback session. The conclusion was that the hypothesis cannot be rejected, but the result is too weak to strengthen it much. Further research is needed to draw more conclusions about the time frame of HRV elevations in healthy people. 

  • 20.
    Sundell, Jonas
    et al.
    KTH, School of Technology and Health (STH), Health Systems Engineering, Ergonomics.
    Dogan, Dilber
    KTH, School of Technology and Health (STH), Health Systems Engineering, Ergonomics.
    Finns det indikationer på samband mellan företags arbetsmiljöarbete och deras börsvärde?: En studie av arbetsmiljöarbetets-indikatorer och börsvärde hos ett urval svenska företag2015Independent thesis Advanced level (degree of Master (Two Years)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The aim of the study was to use SAM-index data and data on factors from the report Det Goda Arbetet from the Swedish Work Environment Authority and identify if there is any relation between listed companies' market values and their systematic work environment management. This master’s work is limited to Forty-seven companies on the Swedish stock market that responded to the Work Environment Authority survey NU2012.

     

    The method in this study is a quantitative approach in which statistical, quantifiable results were sought. The companies that participated in the NU2012 survey was divided into three groups based on their results from: i) Work Environment SAM index data and ii) data on factors from the report Det Goda Arbetet.

     

    Results from SAM- index data show a relation between companies’ systematic work environment management and market capitalization for the year 2012 while the results from Det Goda Arbetet show that scores for the highest average varies between the groups. Results for the years 2008-2011 (the year when we don`t have access to the baseline study) shows that there is a tendency for a relation between share price, turnover, number of employees and work environment for these years.

     

    The main conclusion based on the analyzes of the data on the share price and the work environment in Sweden as well as the literature review included in the study, it is found that companies that have a good work Environment tend to have higher stock price and better stock market performance than companies with poor work environment management.

    Keywords: Work environment, SAM index, Stock price, Quality, Skills, Productivity.

  • 21.
    Terrin, Massimo
    KTH, School of Technology and Health (STH).
    Micro-CT for small animal imaging: Optimization of the tube voltage for low-contrast imaging2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This master thesis evaluated the optimal tube voltage for low-contrast imaging of a micro-CT system (intended for small animal imaging) built at the School of Technology and Health (STH) of the Royal Institute of Technology (KTH).

    The main goal of this work was to calibrate the above-mentioned device (composed moreover by a Hamamatsu microfocus L10951-01 X-ray tube, a CMOS flat panel Hamamatsu C7942CA-22 and using a Cone-Beam CT reconstruction algorithm) for obtaining the best imaging of low-contrast structures. In order to do this, an analytical model, re-adapted from the previous state-of-the-art Micro-CT studies, was evaluated for finding a sub-optimal tube voltage from which to start the experiments, done on a reference Low-Contrast phantom specifically intended for the calibration of Micro-CT devices. 

    Finally, by looking to the results from the experiments, a good tube setting for the optimization of the CT for low-contrast imaging was found. The optimal tube voltage for low-contrast imaging, from the experiments on the QRM phantom, was found to be between 48 and 50 kV. This tube voltage values gave the best CNR and contrast profiles results. 

    Ultimately, we found that the usage of a 1mm Al filtration reduced the absorbed dose without affecting the image quality.

  • 22.
    Thorsteinsdottir, Arnrun
    KTH, School of Technology and Health (STH).
    Motivation and Quantification of Physical Activity for Hospitalised Cancer Patients2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Previous studies have shown the positive effect of increased physical activity for cancer patients during treatments of chemotherapy and stem cell transplantation. Moderate exercise has shown to cause significantly less loss of muscle mass, less symptoms of cancer related fatigue, less need for platelet transfusions during treatment time and shorter hospitalisation. Inactivity at hospital clinics is though still a major concern and it seems like lack of motivation plays a big roll. It has been shown that an overview of activity level, personal goal setting and education on the importance of physical activity can work as a motivation towards increased physical activity. This project aimed to make a prototype that can quantify physical activity of hospitalised cancer patients and represent it in a motivational and informative way. An accelerometer was used to collect activity data; the data was processed and used to train a support vector machine for classification of activities. Activities recognised by the prototype are the postures lying down, sitting and standing as well as recognising when the user is active. Over 90% accuracy was obtained in activity recognition for specific training sets. The prototype was tested on patients at the haematology clinic at the Karolinska hospital in Huddinge. Test subjects rated the classification accuracy and the motivational value of the prototype on a scale of 1-5. The accuracy was rated 4.2 out of 5 and the motivational value 3.25 out of 5. A pilot study to further test the feasibility of the product will be performed in the summer of 2015. 

  • 23.
    Vendrametto, Tobia
    KTH, School of Technology and Health (STH). Politecnico di Milano.
    Robot Assisted Stapedotomy With an Active Handheld Instrument2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Robotic-assisted surgery is a rapid growing field, facing challenging tasks and demands from surgeons, in particular in minimally invasive and microsurgery. However many of the present robotic systems are not well integrated in the surgical workflow, too big or too expensive. Micron is an innovative fully handheld active micromanipulator that helps surgeons to improve position accuracy and precision in microsurgery by cancelling the normal hand tremor. This thesis proposes an improvement and development of Micron, considering as target the stapedotomy procedure, microsurgery performed at the middle ear that aims to restore the hearing impairments. Two tools, a handle and a brace were designed and prototyped and the control was adapted; at the end the entire system was assessed through some experiments. Promising results were obtained in terms of tremor cancellation but further research is needed in order to reach clear advantages. 

  • 24.
    Wang, Beien
    KTH, School of Technology and Health (STH).
    3D Scintillation Positioning Method in a Breast-specific Gamma Camera2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In modern clinical practice, gamma camera is one of the most important imaging modalities for tumour diagnosis. The standard technique uses scintillator-based gamma cameras equipped with parallel-hole collimator to detect the planar position of γ photon interaction (scintillation). However, the positioning is of insufficient resolution and linearity for breast imaging. With the aim to improve spatial resolution and positioning linearity, a new gamma camera configuration was described specifically for breast-imaging. This breast-specific gamma camera was supposed to have the following technical features: variable angle slant-hole collimator; double SiPM arrays readout at the front and back sides of the scintillator; diffusive reflectors at the edges around the scintillator. Because slant-hole collimator was used, a new 3D scintillation positioning method was introduced and tested. The setup of the gamma detector was created in a Monte Carlo simulation toolkit, and a library of a number of light distributions from known positions was acquired through optical simulation. Two library-based positioning algorithms, similarity comparison and maximum likelihood, were developed to estimate the 3D scintillation position by comparing the responses from simulated gamma interactions and the responses from library. Results indicated that the planar spatial resolution and positioning linearity estimated with this gamma detector setup and positioning algorithm was higher than the conventional gamma detectors. The depth-of-interaction estimation was also of high linearity and resolution. With the results presented, the gamma detector setup and positioning method is promising in future breast cancer diagnosis.

  • 25.
    Wang, Beien
    KTH, School of Technology and Health (STH), Medical Engineering.
    3D Scintillation Positioning Method in a Breast-specific Gamma Camera2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In modern clinical practice, gamma camera is one of the most important imaging modalities for tumour diagnosis. The standard technique uses scintillator-based gamma cameras equipped with parallel-hole collimator to detect the planar position of γ photon interaction (scintillation). However, the positioning is of insufficient resolution and linearity for breast imaging. With the aim to improve spatial resolution and positioning linearity, a new gamma camera configuration was described specifically for breast-imaging. This breast-specific gamma camera was supposed to have the following technical features: variable angle slant-hole collimator; double SiPM arrays readout at the front and back sides of the scintillator; diffusive reflectors at the edges around the scintillator. Because slant-hole collimator was used, a new 3D scintillation positioning method was introduced and tested. The setup of the gamma detector was created in a Monte Carlo simulation toolkit, and a library of a number of light distributions from known positions was acquired through optical simulation. Two library-based positioning algorithms, similarity comparison and maximum likelihood, were developed to estimate the 3D scintillation position by comparing the responses from simulated gamma interactions and the responses from library. Results indicated that the planar spatial resolution and positioning linearity estimated with this gamma detector setup and positioning algorithm was higher than the conventional gamma detectors. The depth-of-interaction estimation was also of high linearity and resolution. With the results presented, the gamma detector setup and positioning method is promising in future breast cancer diagnosis.

  • 26.
    Wang, Jing
    KTH, School of Technology and Health (STH).
    Design and implementation of an impedance analyzer based on Arduino Uno: A pilot study of bioelectrical impedance analysis2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Electrical bioimpedance measurement is widely used today for monitoring body condition. The applications include and go beyond, body composition assessment, nutritional status evaluation, and cancer detection. The modalities for interpreting the impedance information have also developed quickly over the recent decades from single frequency bioimpedance analysis to spectrum and to images.

    Bioimpedance is measured by computing the relationship between voltage and current. In a current based bioimpedance measurement system, the stability of current source has a large influence on the performance of the system. This thesis compared three different voltage controlled current sources: enhanced Howland circuit, load-in-the-loop circuit driven by a current conveyor and double operational amplifiers circuit. These circuits were simulated in Multisim and manufactured into prototypes and tested in lab.

    Effort has also been made to generate and collect signals with digital-to-analog convertor and analog-to-digital convertor. They were controlled by Arduino Uno and impedance was analyzed in Matlab.

  • 27.
    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.

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