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  • 1.
    Aare, Magnus
    et al.
    KTH, Skolan för teknik och hälsa (STH), Neuronik (Stängd 20130701).
    Kleiven, Svein
    KTH, Skolan för teknik och hälsa (STH), Neuronik (Stängd 20130701).
    Evaluation of head response to ballistic helmet impacts, using FEM2003Konferansepaper (Fagfellevurdert)
  • 2.
    Aare, Magnus
    et al.
    KTH, Skolan för teknik och hälsa (STH), Neuronik (Stängd 20130701).
    Kleiven, Svein
    KTH, Skolan för teknik och hälsa (STH), Neuronik (Stängd 20130701).
    Halldin, Peter
    KTH, Skolan för teknik och hälsa (STH), Neuronik (Stängd 20130701).
    Proposed global injury thresholds for oblique helmet impacts2003Konferansepaper (Fagfellevurdert)
  • 3.
    Abedan Kondori, Farid
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Yousefi, Shahrouz
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Liu, Li
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Active human gesture capture for diagnosing and treating movement disorders2013Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Movement disorders prevent many people fromenjoying their daily lives. As with other diseases, diagnosisand analysis are key issues in treating such disorders.Computer vision-based motion capture systems are helpfultools for accomplishing this task. However Classical motiontracking systems suffer from several limitations. First theyare not cost effective. Second these systems cannot detectminute motions accurately. Finally they are spatially limitedto the lab environment where the system is installed. In thisproject, we propose an innovative solution to solve the abovementionedissues. Mounting the camera on human body, webuild a convenient, low cost motion capture system that canbe used by the patient in daily-life activities. We refer tothis system as active motion capture, which is not confinedto the lab environment. Real-time experiments in our labrevealed the robustness and accuracy of the system.

  • 4.
    Abtahi, Farhad
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Towards Heart Rate Variability Tools in P-Health: Pervasive, Preventive, Predictive and Personalized2016Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Heart rate variability (HRV) has received much attention lately. It has been shown that HRV can be used to monitor the autonomic nervous system and to detect autonomic dysfunction, especially vagal dysfunction. Reduced HRV is associated with several diseases and has also been suggested as a predictor of poor outcomes and sudden cardiac death. HRV is, however, not yet widely accepted as a clinical tool and is mostly used for research. Advances in neuroimmunity with an improved understanding of the link between the nervous and immune systems have opened a new potential arena for HRV applications. An example is when systemic inflammation and autoimmune disease are primarily caused by low vagal activity; it can be detected and prognosticated by reduced HRV. This thesis is the result of several technical development steps and exploratory research where HRV is applied as a prognostic diagnostic tool with preventive potential. The main objectives were 1) to develop an affordable tool for the effective analysis of HRV, 2) to study the correlation between HRV and pro-inflammatory markers and the potential degree of activity in the cholinergic anti-inflammatory pathway, and 3) to develop a biofeedback application intended for support of personal capability to increase the vagal activity as reflected in increased HRV. Written as a compilation thesis, the methodology and the results of each study are presented in each appended paper. In the thesis frame/summary chapter, a summary of each of the included papers is presented, grouped by topic and with their connections. The summary of the results shows that the developed tools may accurately register and properly analyse and potentially influence HRV through the designed biofeedback game. HRV can be used as a prognostic tool, not just in traditional healthcare with a focus on illness but also in wellness. By using these tools for the early detection of decreased HRV, prompt intervention may be possible, enabling the prevention of disease. Gamification and serious gaming is a potential platform to motivate people to follow a routine of exercise that might, through biofeedback, improve HRV and thereby health.

  • 5.
    Abtahi, Farhad
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system. Karolinska Institutet, Sweden.
    Hilderman, Marie
    Bruchfeld, Annette
    Seoane, Fernando
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system. University of Borås, Sweden.
    Janerot-Sjöberg, Birgitta
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinsk bildteknik. Karolinska Institutet, Sweden.
    Lindecrantz, Kaj
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system. Karolinska Institutet, Sweden.
    Pro-inflammatory Blood Markers and Heart Rate Variability in Apnoea as a Reflection of Basal Vagal ToneManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Pro-inflammatory cytokines play a crucial role in inflammatory response, which istightly regulated by the nervous system to avoid the damage caused by inflammation. There isevidence for a cholinergic anti-inflammatory pathway that includes afferent and efferent vagalnerves that sense the inflammation and stimulate the anti-inflammatory response. Non-functionalanti-inflammatory response might lead to excessive and chronic inflammation e.g., rheumatoidarthritis (RA), inflammatory bowel disease (IBD), and poor outcome. Heart rate variability(HRV) has been proposed as a potential tool to monitor the level of anti-inflammatory activitythrough the monitoring of vagal activity. In this paper, the association of pro-inflammatorymarkers with HRV indices is evaluated. We used a database called “Heart Biomarker Evaluationin Apnea Treatment (HeartBEAT)” that consists of 6±2 hours of Electrocardiogram (ECG)recordings during nocturnal sleep from 318 patients at baseline and 301of them at 3 monthsfollow-up. HRV indices are calculated from ECG recordings of 5-360 minutes. The results showa statistically significant correlation between heart rate (HR) and pro-inflammatory cytokines,independent of duration of ECG analysis. HRV indices e.g., standard deviation of all RRintervals (SDNN) show an inverse relation to the pro-inflammatory cytokines. Longer ECGrecordings show a higher potential to reflect the level of anti-inflammatory response. In light oftheories for the cholinergic anti-inflammatory pathway, a combination of HR and HRV as areflection of basal vagal activity might be a potential prognostic tool for interventional guidance.

  • 6.
    Abtahi, Farhad
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Seoane, Fernando
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Lindecrantz, Kaj
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinska sensorer, signaler och system.
    Löfgren, Nils
    Elimination of ECG Artefacts in Foetal EEG Using Ensemble Average Subtraction and Wavelet Denoising Methods: A Simulation2014Inngår i: XIII Mediterranean Conference on Medical and Biological Engineering and Computing 2013, Springer, 2014, 551-554 s.Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Biological signals recorded from surface electrodes contain interference from other signals which are not desired and should be considered as noise. Heart activity is especially present in EEG and EMG recordings as a noise. In this work, two ECG elimination methods are implemented; ensemble average subtraction (EAS) and wavelet denoising methods. Comparison of these methods has been done by use of simulated signals achieved by adding ECG to neonates EEG. The result shows successful elimination of ECG artifacts by using both methods. In general EAS method which remove estimate of all ECG components from signal is more trustable but it is also harder for implementation due to sensitivity to noise. It is also concluded that EAS behaves like a high-pass filter while wavelet denoising method acts as low-pass filter and hence the choice of one method depends on application.

  • 7.
    Agnvall, Beatrix
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Bélteky, Johan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Jensen, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Brain size is reduced by selectionfor tameness in Red Junglefowl–correlated effects in vital organs2017Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, 3306Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    During domestication animals have undergone changes in size of brain and other vital organs. We hypothesize that this could be a correlated effect to increased tameness. Red Junglefowl (ancestors of domestic chickens) were selected for divergent levels of fear of humans for five generations. The parental (P0) and the fifth selected generation (S5) were culled when 48–54 weeks old and the brains were weighed before being divided into telencephalon, cerebellum, mid brain and optic lobes. Each single brain part as well as the liver, spleen, heart and testicles were also weighed. Brains of S5 birds with high fear scores (S5 high) were heavier both in absolute terms and when corrected for body weight. The relative weight of telencephalon (% of brain weight) was significantly higher in S5 high and relative weight of cerebellum was lower. Heart, liver, testes and spleen were all relatively heavier (% of body weight) in S5 high. Hence, selection for tameness has changed the size of the brain and other vital organs in this population and may have driven the domesticated phenotype as a correlated response.

  • 8.
    Ahlström, Christer
    et al.
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Dukic, Tania
    Statens väg- och transportforskningsinstitut, Trafik och trafikant,TRAF, Samspel människa, fordon, transportsystem, MFT.
    Comparison of eye tracking systems with one and three cameras2011Inngår i: ACM International Conference Proceeding Series, 2011Konferansepaper (Fagfellevurdert)
    Abstract [en]

    When using eye movements to determine the state of a car driver it is important that the eye tracker is robust, unobtrusive, inexpensive and fully automatic. The objectives of this study are to compare the performance of a one-camera system with a three-camera system and to investigate if the accuracy and availability of the one-camera system is sufficient to monitor driver state. Data from 53 subjects were evaluated and the results indicate that there is not much difference between a single-camera system and a multi-camera system as long as the driver is looking straight ahead. However, with more peripheral gaze directions, the larger coverage that is provided by the additional cameras works in favour of the multi-camera system. © ACM 2010.

  • 9.
    Ahnesjö, Anders
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för immunologi, genetik och patologi, Medicinsk strålningsvetenskap.
    Patient Dose Computation2014Inngår i: Comprehensive Biomedical Physics: Volume 9: Radiation Therapy Physics and Treatment Optimization / [ed] Anders Brahme, Amsterdam: Elsevier, 2014, 235-247 s.Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    Various dose calculation methods have been proposed to serve the needs in treatment planning of radiotherapy. Common to these are that they need a patient model to describe the interaction properties of the irradiated tissues, and a sufficiently accurate description of the incident radiation. This chapter starts with a brief review of the contexts in which patient dose calculations may serve, followed by a description of common methods for patient modelling and beam characterization. The focus is on external beam photon, but also partly covers particle beams like electrons and protons. The last section describes common approaches of varying complexity for dose calculations ranging from simple factor based models, more elaborate pencil and point kernel models, and finally summarizes some aspects of Monte Carlo and grid based methods.

  • 10.
    Ajaxon, Ingrid
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Holmberg, Anders
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Öhman Mägi, Caroline
    Persson, Cecilia
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Fatigue life of a brushite cement under cyclic compressive loading2017Konferansepaper (Fagfellevurdert)
  • 11.
    Akay, Altug
    KTH, Skolan för teknik och hälsa (STH), Hälso- och systemvetenskap, Systemsäkerhet och organisation.
    A Novel Method to Intelligently Mine Social Media to Assess Consumer Sentiment of Pharmaceutical Drugs2017Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis focuses on the development of novel data mining techniques that convert user interactions in social media networks into readable data that would benefit users, companies, and governments. The readable data can either warn of dangerous side effects of pharmaceutical drugs or improve intervention strategies. A weighted model enabled us to represent user activity in the network, that allowed us to reflect user sentiment of a pharmaceutical drug and/or service. The result is an accurate representation of user sentiment. This approach, when modified for specific diseases, drugs, and services, can enable rapid user feedback that can be converted into rapid responses from consumers to industry and government to withdraw possibly dangerous drugs and services from the market or improve said drugs and services.

    Our approach monitors social media networks in real-time, enabling government and industry to rapidly respond to consumer sentiment of pharmaceutical drugs and services.

  • 12.
    Al-Absi, Thabit
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Bioinformatik. Linköpings universitet, Tekniska högskolan.
    Efficient Characterization of Short Anelloviruses Fragments Found in Metagenomic Samples2012Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Some viral metagenomic serum samples contain a huge amount of Anellovirus, which is a genetically diverse family with a few conserved regions making it hard to efficiently characterize. Multiple sequence alignment of the Anelloviruses found in the sample must be constructed to get a clear picture of Anellovirus diversity and to identify stable regions. Using available multiple sequence alignment software directly on these fragments results in an MSA of a very poor quality due to their diversity, misaligned regions and low-quality regions present in the sequence.

    An efficient MSA must be constructed in order to characterize these Anellovirus present in the samples. Pairwise alignment is used to align one fragment to the database sequences at a time. The fragments are then aligned to the database sequences using the start and end position from the pairwise alignment results. The algorithm will also exclude non-aligned portions of the fragments, as these are very hard to handle properly and are often products of misassembly or chimeric sequenced fragments. Other tools to aid further analysis were developed, such as finding a non-overlapping window that contains the most fragments, find consensus of the alignment and extract any regions from the MSA for further analysis.

    An MSA was constructed with a high percent of correctly aligned bases compared to an MSA constructed using MSA softwares. The minimal number of genomes found in the sampled sequence was found as well as a distribution of the fragments along the database sequence. Moreover, highly conserved region and the window containing most fragments were extracted from the MSA and phylogenetic trees were constructed for these regions. 

  • 13.
    Albano, Amanda
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Exploratory statistical study of long-term variability in echocardiographic indices (echocardiovariability) in healthy and diseased1987Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Heart rate variability, HRV, has been well researched for some decades. The oscillations of the heart rate is studied over a time period of some minutes up to 24 hours, it is measured with electrocardiography, ECG. From this one has concluded that the heart rate signal oscillates in accordance with the respiration, the resistance in the vessels etc.

    The most frequently used examination method of the heart is done with ultrasound, called echocardiography. One interesting variable at a time is measured and it is measured for a single heartbeat. With inspiration ofthe HRV studies this project focuses on some of the variables measured with ultrasound but over time andsimultaneously. The variables of interest are the myocardial motion and the blood flow in the left part ofthe heart, they are measured over two minutes. To complement these variables the well known variables HRand Resp are measured with ECG and added to the analysis.

    The methods used for analysing the variables are first of all descriptive statistics like mean and standard deviation. Secondly spectral analysis is performed to investigate in which frequencies the variables oscillates. Through coherence this is compared with the spectrum for HR where the three peaks have known origin. Finally principal component analysis, PCA, is performed as a method to compare all variables at the same time.

    The analyses are performed on seven measurements from five (5) healthy persons and five measurementsfrom four (4) patients with the disease FAP (“Skelleftesjukan”). The variables are investigated and described for the healthy persons first, then the healthy persons and patients are compared.

    The result from the study shows that most of the echo-variables oscillate in accordance with the respirationand the heart rate. For a healthy person the oscillations are within normal values and the relative deviation isaround 10%. The patients with FAP are most affected in the variables connected to the myocardium apartfrom HR, which is known since before.

    The coherence between the echo-variables and HR is low in one of VLF, very low frequency, or LF, lowfrequency, region and high in the other. In HF, high frequency, region the coherence is high for all variables.

    Finally the PCA was conducted on measurements from all healthy persons as one data set, from one ofthe healthy persons and from one of the patients with FAP. The analysis showed that for healthy personsrespiration is the process causing most variation and all of the echo-variables have a correlation to therespiration. For a patient with FAP the respiration is not as salient. A PCA over blocks of data at different time points however show that the signals are not oscillating in the same way multivariately over the wholetime series.

  • 14.
    Alonso, Fabiola
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan.
    Modeling and simulation of DBS – comparison between leads and stimulation modes2014Konferansepaper (Annet vitenskapelig)
  • 15.
    Alonso, Fabiola
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan.
    Wårdell, Karin
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska högskolan.
    Comparison of deep brain stimulation systems2014Inngår i: Poster Presentations, 2014, Vol. 29, 1173-1173 s., Suppl 1Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Objective: To quantitatively compare the electric field generated by voltage and current controlled deep brain stimulation systems.

    Background: Traditionally deep brain stimulation (DBS) systems have used voltage control however more recently, current controlled systems have been approved to treat Parkinson's disease and related movement disorders. In the endeavor of understanding the behavior of DBS systems a common approach is the use of computer models suitable to simulate the electric field, current density and other related electric parameters.

    Methods: 2D finite element models based on commercially available DBS systems have been built for each system: I. Model 3389, Medtronic Inc., USA for voltage control; and II. Model 6142, St Jude Medical Inc. USA for current control. The brain tissue has been simplified to homogeneous and isotropic medium. The electric settings correspond to a monopolar configuration, using one of the four contacts available as the active electrode and the outer boundary of the tissue as the reference. Three simulations were performed to mimic different stages of the leads implantation: a) an original stage where the brain tissue is considered as pure gray matter, b) an acute stage that simulates the leakage of cerebral spinal fluid immediately after the electrodes' insertion; and c) a chronic stage mimicking fibrous tissue created around the electrodes some weeks after implantation. Both systems were submitted to the same conditions using as active electrode the third contact from the tip of the lead. The comparison is based on the maximal distance reached by the isopotential of 0.2 V/mm.

    Results: The simulations showed that voltage controlled stimulation systems are more susceptible to changes in the electrical conductivity of the medium i.e. change over time of the tissue around the electrode. This agrees with the adjustment of the stimulation amplitude often necessary a few weeks postoperatively. Current controlled stimulation in turn, presented a linear behavior of the distance reached at different stimulation amplitudes at all stages.

    Conclusions: Current controlled stimulation might be a good option due to its linear behavior over time, nevertheless more studies including a more realistic brain model, different designs of DBS electrodes and different electric parameter, are needed to encourage the use of this type of systems.

  • 16.
    Alonso, Fabiola
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska fakulteten.
    Wårdell, Karin
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska fakulteten.
    Latorre, Malcolm
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska fakulteten.
    Comparison of Three Deep Brain Stimulation Lead Designs under Voltage and Current Modes2015Inngår i: WORLD CONGRESS ON MEDICAL PHYSICS AND BIOMEDICAL ENGINEERING, 2015, VOLS 1 AND 2 / [ed] David A. Jaffray, Springer, 2015, Vol. 51, 1196-1199 s.Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Since the introduction of deep brain stimulation (DBS) the technique has been dominated by Medtronic sys-tems. In recent years, new DBS systems have become available for patients, and some are in clinical trials. The present study aims to evaluate three DBS leads operated in either voltage or current mode. 3D finite element method (FEM) models were built in combination with a neuron model for this purpose. The axon diameter was set to D = 5 μm and simulations performed in both voltage (0.5-5 V) and current (0.5-5 mA) mode. The evaluation was achieved based on the distance from the lead for neural activation and the electric field (EF) extension at 0.1 V/mm. The results showed that the neural activation distance agrees well between the leads with an activation distance dif-ference less than 0.5 mm. The shape of the field at the 0.1 V/mm isopotential surface in 3D is mostly spherical in shape around the activated section of the steering lead.

  • 17.
    Alonso, Fabiola
    et al.
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska fakulteten.
    Wårdell, Karin
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska fakulteten.
    Latorre, Malcolm
    Linköpings universitet, Institutionen för medicinsk teknik, Biomedicinsk instrumentteknik. Linköpings universitet, Tekniska fakulteten.
    Neural Activation Compared to Electric Field Extension of Three DBS Lead Designs2015Konferansepaper (Fagfellevurdert)
    Abstract [en]

    SINCE the introduction of deep brain stimulation (DBS) about 20 years ago, the stimulation technique has been dominated by Medtronic DBS-system setup. In recent years, new DBS systems have become available, of which some are in clinical trials or available to patients [1]. In the present study three different lead designs are investigated via computer simulation:

    Medtronic 3389, St. Jude 6148 and Sapiens SureStim. The aim was to compare the neural activation distance and the electric field (EF) maximum spatial extension for each lead.

    A 3D finite element method model was built using COMSOL Multiphysics 4.4a (COMSOL AB, Stockholm, Sweden) to simulate the electric potential around the DBS lead. Brain tissue was modelled as a homogeneous volume of grey matter (electric conductivity of 0.09 S/m). The electrode-tissue interface was modelled with a 250μm thick peri-electrode space mimicking the fibrous tissue which covers the lead at the chronic stimulation stage (σ = 0.06S/m, equivalent to white matter electric conductivity). The stimulation amplitude was set to 1V in monopolar configuration using C1 electrode or equivalent in all cases. Each simulated electric potential distribution was exported to MatLab (The MathWorks, USA) and used as input to a cable neuron simulation.

    An axon cable model with 21 nodes based on the concept by Åström et al., [2] was set up in MatLab and combined with the exported field distributions. The model considered a 5 μm thick neuron, a pulse width of 60 μs and a drive potential ranging from 0.5 V to 5 V in 0.5 V steps.

    The SureStim lead results showed a shorter neural activation distance and EF extension. The distance to the isolevel of 0.2 V/mm is close to the neural activation distance at each stimulation amplitude, and we conclude that the electric field is a suitable predictor to visualize the stimulated regions.

  • 18.
    Alrifaiy, Ahmed
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    A gastight microfluidic system combined with optical tweezers and optical spectroscopy for electrophysiological investigations of single biological cells2011Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Stroke affects around 20 million people around the world every year. Clinically, stroke is a result of brain damage due to the shortage of oxygen delivered to the nerve cells. To minimize suffering and costs related to the disease, extensive research is performed on different levels. The focus of our research is to achieve fundamental understanding on how the lack of oxygen in brain tissue activates intrinsic biomolecular defense mechanisms that may reduce brain damage. More knowledge may hopefully lead to new therapeutic and preventive strategies on the molecular level for individuals in the risk zone for stroke or those who have just suffered a stroke. The area of study is based on the discovery of a hemoprotein called neuroglobin (Ngb), which is found in various regions in the brain, in the islets of Langerhans, and in the retina. Several studies have shown that Ngb seems to have a protective function against hypoxia-related damage. However, until now, it has not been understood how Ngb affects the nerve system and protects neurons from damage. The well-established patch-clamp technique is routinely used to measure and analyze the electrophysiological activity of individual biological cells. To perform accurate patchclamp experiments, it is important to create well-controlled physiological conditions, i.e. different oxygen levels and fast changes of nutrients and other biochemical substances. A promising approach is to apply lab-on-a-chip technologies combined with optical manipulation techniques. These give optimal control over fast changing environmental conditions and enable multiple readouts. The conventional open patch-clamp configuration cannot provide adequate control of the oxygen content. Therefore, it was substituted by a gas-tight multifunctional microfluidic system, a lab-on-a-chip, with an integrated patch-clamp micropipette. The system was combined with optical tweezers and optical spectroscopy. Laser tweezers were used to optically guide and steer single cells towards the fixed micropipette. Optical spectroscopy was used to investigate the biochemical composition of the sample. The designed, closed lab-on-a-chip acted as a multifunctional system for simultaneous electrophysiological and spectroscopic experiments with good control over the oxygen content in the liquid perifusing the cells. The system was tested in a series of experiments: optically trapped human red blood cells were steered to the fixed patch-clamp pipette within the microfluidic system. The oxygen content within the microfluidic channels was measured to 1 % compared to the usual 4-7 %. The trapping dynamics were monitored in real-time while the spectroscopic measurements were performed simultaneously to acquire absorption spectra of the trapped cell under varying environments. To measure the effect of the optical tweezers on the sample, neurons from rats in a Petri dish were optically trapped and steered towards the patch-clamp micropipette where electrophysiological investigations were performed. The optical tweezers had no effect on the electrophysiological measurements. Similar investigations within a closed microfluidic system were initiated and showed promising results for further developments of a complete lab-on-a-chip multifunctional system for reliable patch-clamp measurements. The future aim is to perform complete protocols of patch-clamp electrophysiological investigations while simultaneously monitoring the biochemical composition of the sample by optical spectroscopy. The straightforwardness and stability of the microfluidic chip have shown excellent potential to enable high volume production of scalable microchips for various biomedical applications. The subsequent ambition is to use this system as a mini laboratory that has benefits in cell sorting, patch-clamp, and fertilization experiments where the gaseous and the biochemical content is of importance. The long-term goal is to study the response of individual neurons and defense mechanisms under hypoxic conditions that may establish new ways to understand cell behavior related to Ngb for various diseases such as stroke, Alzheimer’s and Parkinson’s.

  • 19.
    Alrifaiy, Ahmed
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Lab on a chip for electrophysiological measurements with control of the oxygen content: optical manipulation and spectroscopic analysis of biological cells2013Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Stroke affects nearly 20 million people around the world every year. Clinically, stroke is a result of brain damage due to the shortage of oxygen delivered to the nerve cells. To minimize suffering and costs related to the disease, extensive research is performed on different levels. The focus of our research is to achieve fundamental understanding on how the lack of oxygen in brain tissue activates intrinsic biomolecular defense mechanisms that may reduce brain damage. More knowledge may hopefully lead to new therapeutic and preventive strategies on the molecular level for individuals in the risk zone for stroke or those who have just suffered a stroke.The area of study is based on the discovery of a hemoprotein called neuroglobin (Ngb), which is found in various regions in the brain, in the islets of Langerhans, and in the retina. Several studies have shown that Ngb seems to have a protective function against hypoxia-related damage. However, until now, it has not been understood how Ngb affects the nerve system and protects neurons from damage.The well-established patch-clamp technique is routinely used to measure and analyze the electrophysiological activity of individual biological cells. To perform accurate patchclamp experiments, it is important to create well-controlled physiological conditions, i.e. different oxygen levels and fast changes of nutrients and other biochemical substances. A promising approach is to apply lab on a chip technologies combined with optical manipulation techniques. These give optimal control over fast changing environmental conditions and enable multiple readouts.The conventional open patch-clamp configuration cannot provide adequate control of the oxygen content. Therefore, the aim of the thesis was to design and test a multifunctional microfluidic system, lab on a chip (LOC), that can achieve normoxic, anoxic and hypoxic conditions. The conventional patch clamp configuration was substituted by a gas-tight LOC system with an integrated patch-clamp micropipette. The system was combined with optical tweezers, optical sensor and optical spectroscopy.Optical tweezers were used to trap and guide single cells through the LOC microchannels towards the fixed micropipette. Optical spectroscopy was essential to investigate the biochemical composition of the biological samples. The developed, gas-tight LOC acted as a multifunctional system for simultaneous electrophysiological and spectroscopic experiments with good control over the oxygen content in the liquid perifusing the cells. The system was tested in series of experiments: optically trapped cells (red blood cells from human and chicken and nerve cells) were steered to the fixed patch-clamp pipette within the LOC system. The oxygen content within the microfluidic channels was measured to ∼ 1% compared to the usual 4-7% found in open system. The trapping dynamics were monitored in real-time while the spectroscopic measurements were performed simultaneously to acquire absorption spectra of the trapped cell under varying environments. To measure the effect of the laser tweezers on the sample, neurons from rats in a Petri dish were optically trapped and steered towards the patch-clamp micropipette where electrophysiological investigations were performed. The optical tweezers had no effect on the electrophysiological measurements.The future aim is to perform complete protocols of patch-clamp electrophysiological investigations while simultaneously monitoring the biochemical composition of the sample by optical spectroscopy. The straightforwardness and stability of the microfluidic chip have shown excellent potential to be applied for various biomedical applications. The subsequent ambition is to use this system as a mini laboratory that has benefits in cell sorting, patch-clamp and fertilization experiments where the gaseous and the biochemical content is of importance.The long-term goal is to study the response of individual neurons and defense mechanisms under hypoxic conditions that may establish new ways to understand cell behavior related to Ngb for various diseases such as stroke, Alzheimer’s and Parkinson’s.

  • 20.
    Alrifaiy, Ahmed
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Bitaraf, Nazanin
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Druzin, Michael
    Umeå universitet, Integrativ Medicinsk Biologi, Fysiologi.
    Lindahl, Olof
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Ramser, Kerstin
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Hypoxia on a chip: a novel approach for patch-clamp studies in a microfluidic system with full oxygen control2012Inngår i: World Congress on Medical Physics and Biomedical Engineering, May 26-31, 2012, Beijing, China / [ed] Mian Long, Berlin: Encyclopedia of Global Archaeology/Springer Verlag, 2012, 313-316 s.Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Here a new approach to perform patch-clamp investigations under anoxic and normoxic conditions on nerve cells from Sprague Dawley rats is presented. A patch-clamp micropipette is integrated within a poly-methyl methacrylate (PMMA) based microchip giving optimal control over the oxygen content and the biochemical environment. Nerve cells were trapped by optical tweezers and steered towards the patch-clamp micropipette within the micro-channels. Several experiments were performed to show proof of principle. The oxygen content within the microfluidic chamber was measured to 0.5-1.5 %. The photo-induced effect of the optical tweezers on the nerve cells was investigated in an open Petri dish. The optical trapping did not influence measurements. The microfluidic system was further tested in patch-clamp experiments. This approach showed significant advantages regarding the tuning of the oxygen content and may be used in various electrophysiological investigations of single cells demanding optimal control of the surroundings.

  • 21.
    Alrifaiy, Ahmed
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Bitaraf, Nazanin
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Druzin, Michael
    Umeå universitet, Integrativ Medicinsk Biologi, Fysiologi.
    Lindahl, Olof
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Ramser, Kerstin
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Patch-clamp measurements on a chip with full control over the oxygen content2012Inngår i: Journal of Biochips & Tissue Chips, ISSN 2153-0777, Vol. 2, nr 1, 1-5 s.Artikkel i tidsskrift (Fagfellevurdert)
  • 22.
    Alrifaiy, Ahmed
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Bitaraf, Nazanin
    Lindahl, Olof
    Ramser, Kerstin
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Development of microfluidic system and optical tweezers for electrophysiological investigations of an individual cell2010Inngår i: Optical Trapping and Optical Micromanipulation VII: 1 - 5 August 2010, San Diego, California, United States ; [part of SPIE optics + photonics] / [ed] Kishan Dholakia; Gabriel C. Spalding, Bellingham, Wash: SPIE - International Society for Optical Engineering, 2010Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We present a new approach of combining Lab-on-a-chip technologies with optical manipulation technique for accurate investigations in the field of cell biology. A general concept was to develop and combine different methods to perform advanced electrophysiological investigations of an individual living cell under optimal control of the surrounding environment. The conventional patch clamp technique was customized by modifying the open system with a gas-tight multifunctional microfluidics system and optical trapping technique (optical tweezers).The system offers possibilities to measure the electrical signaling and activity of the neuron under optimum conditions of hypoxia and anoxia while the oxygenation state is controlled optically by means of a spectroscopic technique. A cellbased microfluidics system with an integrated patch clamp pipette was developed successfully. Selectively, an individual neuron is manipulated within the microchannels of the microfluidic system under a sufficient control of the environment. Experiments were performed to manipulate single yeast cell and red blood cell (RBC) optically through the microfluidics system toward an integrated patch clamp pipette. An absorption spectrum of a single RCB was recorded which showed that laser light did not impinge on the spectroscopic spectrum of light. This is promising for further development of a complete lab-on-a-chip system for patch clamp measurements.

  • 23.
    Alrifaiy, Ahmed
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik.
    Bitaraf, Nazanin
    Luleå tekniska universitet, Institutionen för system- och rymdteknik.
    Lindahl, Olof
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Ramser, Kerstin
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Ett mikroflödessystem för multipla undersökningar av enstaka biologiska celler under hypoxiska förhållanden2011Konferansepaper (Fagfellevurdert)
    Abstract [sv]

    Introduktion: Syftet med studien är att studera enstaka nervcellers respons vid syrebrist i ett mikroflödessystem för att förstå nervcellens respons vid stroke. Målet med studien var att utveckla ett slutet mikroflödessystem som ger optimal kontroll av den omgivande miljön och samtidigt möjliggöra elektrofysiologiska undersökningar under kontrollerade syreförhållande. Material och metoder: Mikroflödescellen utvecklades för ett inverterat mikroskop, utrustad med en optisk pincett och optisk spektroskopi samt patch-clamp för elektrofysiologiska studier på en enstaka nervcell. Istället för att föra en pipett mot en cell i ett öppet system fångades en enskild cell optiskt i ett slutet mikroflödessystem och fördes mot en fixerad patch-clamp mikropipett. Cellen utsattes för olika syrehalter och övervakades av ett UV-Vis spektroskop medan cellens elektrofysiologiska aktivitet registreras med patch-clamp. Det slutna mikroflödessystemet med integrerad mikropipett, kopplades till ett pumpsystem för införandet av celler och buffert med olika kemiska egenskaper och syrehalter. I ett inverterat mikroskop integrerades optisk pincett, UV-Vis spektrometer och patch-clamp. Resultat och diskussion: För att pröva konceptet fångades och fördes en röd blodcell optiskt mot mikropipetten som befann sig på en fast position i mikroflödescellen. Cellens syrebindningstillstånd varierades genom att tillsätta syrefri eller syresatt buffert och registrerades med UV-Vis spektrometern. I ett vidare experiment manipulerades en nervcell optiskt i ett öppet system mot patch-clamp pipetten och elektrofysiologiska mätningar utfördes. Vi kunde verifiera att den optiska pincetten inte påverkade den elektrofysiologiska mätningen. För närvarandet utförs elektrofysiologiska mätningar i det slutna mikroflödessystemet för att se hur nervcellerna reagerar under varierande syrehalt. Genom mätningarna hoppas vi att få mer kunskap om försvarsmekanismerna som igångsätts av neuroner under syrefattiga förhållanden.

  • 24. Alrifaiy, Ahmed
    et al.
    Lindahl, Olof
    Ramser, Kerstin
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Ett mikroflödessystem med optisk pincett och UV- vis för studier på enskilda biologiska celler2010Konferansepaper (Annet vitenskapelig)
  • 25.
    Alrifaiy, Ahmed
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Lindahl, Olof
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Ramser, Kerstin
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Patch-clamp electrophysiological measurements on single cells under hypoxic conditions in microfluidic systems2012Konferansepaper (Fagfellevurdert)
  • 26.
    Alrifaiy, Ahmed
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Lindahl, Olof
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Ramser, Kerstin
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Polymer-based microfluidic devices for pharmacy, biology and tissue engineering2012Inngår i: Polymers, ISSN 2073-4360, E-ISSN 2073-4360, Vol. 4, nr 3, 1349-1398 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper reviews microfluidic technologies with emphasis on applications in the fields of pharmacy, biology, and tissue engineering. Design and fabrication of microfluidic systems are discussed with respect to specific biological concerns, such as biocompatibility and cell viability. Recent applications and developments on genetic analysis, cell culture, cell manipulation, biosensors, pathogen detection systems, diagnostic devices, high-throughput screening and biomaterial synthesis for tissue engineering are presented. The pros and cons of materials like polydimethylsiloxane (PDMS), polymethylmethacrylate (PMMA), polystyrene (PS), polycarbonate (PC), cyclic olefin copolymer (COC), glass, and silicon are discussed in terms of biocompatibility and fabrication aspects. Microfluidic devices are widely used in life sciences. Here, commercialization and research trends of microfluidics as new, easy to use, and cost-effective measurement tools at the cell/tissue level are critically reviewed.

  • 27.
    Alrifaiy, Ahmed
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Ramser, Kerstin
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    How to integrate a micropipette into a closed microfluidic system: absorption spectra of an optically trapped erythrocyte2011Inngår i: Biomedical Optics Express, ISSN 2156-7085, E-ISSN 2156-7085, Vol. 2, nr 8, 2299-2306 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In July 2011 a new concept of a closed microfluidic system equipped with a fixed micropipette, optical tweezers and a UV-Vis spectrometer was presented [Biomed. Opt. Express 2, 2299 (2011)]. Figure 1 showed falsely oriented mirrors. To clarify the design of the setup, this erratum presents a correct schematic

  • 28.
    Andersson, Matilda
    Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap.
    Analysis of Changes in Running Technique Between a Shod and Barefoot Running Condition.2016Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    Background: Lately, barefoot running has become popular and there is a debate on the pros and cons of barefoot running with regards to running injuries. Many factors are causing injuries and one of the factors discussed is the fact that we run in shoes. When we run in shoes the biomechanics of the running technique may and therefore be a possible cause to injury. Aim: The aim of the study was to assess how the foot strike pattern, angle of the knee and ankle joint at time of initial contact, as well as the step length changes between a shod and barefoot running condition in habitually shod runners when running in a pace equivalent to their running pace over ten kilometers. Method: Twenty-seven healthy runners (18 male, 9 female) were included in the study. The study took place at the fitness center of Halmstad University. Subjects ran on a treadmill, in an individual pace equivalent to their running pace over ten km, both in a shod and barefoot running condition. Two-dimensional analysis of the sagittal plane kinematics of the knee joint, ankle joint and foot position to horizontal, foot strike pattern and step length was done. Participants ran for ten minutes with shoes and for five minutes barefoot. Running technique was videotaped using an Iphone 6 camera and landmarks were marked with white tape to ease the analysis. Results: Changes in foot strike pattern was observed. When running barefoot 63% of the subjects adopted a non-heel strike pattern compared to 18.5% when shod (p=0.001). Knee flexion was increased at IC for the barefoot condition, with 164°±6 relative knee angle compared to 167°±6 when shod (p=0.001). Ankle angle at IC did not show a statistical significant difference between conditions (p=0.657). When barefoot the angle was 117°±8 compared to 115°±8 when shod. Foot angle to horizontal showed a flatter foot placement at IC with a less dorsiflexed foot for the barefoot condition (-4°±8) compared to shod (-12°±8), (p=0.001). Step length was decreased for the barefoot condition (0.82m ±0.15)   compared to shod (0.85m ±0.13), (p=0.008). Conclusion: Results are consistent with previous findings that barefoot running in some cases change the running technique with a flatter foot placement, an increased knee flexion at IC and a decreased step length. However, caution must be taken when habitually shod runners transition to barefoot running in regards to the biomechanical changes that may occur. To benefit from barefoot running a non-heel strike pattern is required. Further, the running technique may be the more important factor, regardless of wearing shoes or not.

  • 29.
    Angelopoulos, Angelos
    et al.
    -.
    Aslanides, E.
    -.
    Backenstoss, G.
    -.
    Bargassa, P.
    -.
    Behnke, O.
    -.
    Benelli, A.
    -.
    Bertin, V.
    -.
    Blanc, F.
    -.
    Bloch, P.
    -.
    Carlson, P.
    -.
    Danielsson, Mats
    KTH, Tidigare Institutioner, Fysik.
    K0⇋ K̄0 transitions monitored by strong interactions: a new determination of the K L–K S mass difference2001Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 503, nr 1, 49-57 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

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

  • 30.
    Angland, Erik
    et al.
    Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Karlsson, Henrik
    Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Gustafsson, Agnetha
    Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Pettersson, Håkan
    Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Radiofysikavdelningen US.
    Luftmätningar av  inhalerat 99mTc till BMA vid ventilationsundersökningar med Technegas.2006Konferansepaper (Annet vitenskapelig)
  • 31.
    Antonsson, Jacob
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Motion Tracking Using a Permanent Magnet2013Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    In this project the possibility of using a network of magnetometers sensing a permanent magnet for tracking has been investigated. Both the orientation and the position of the magnet have been considered. A dipole approximation of the magnetic field is used to develop two models. One of the models parametrizes the orientation with the magnetic moment vector, while the other parametrizes the orientation with a unit quaternion. An extended Kalman filter have been used to estimate position and orientation.

    Several calibration algorithms have been developed to calibrate for sensor errors, differences in sensor coordinate frame orientations and also for the estimation of the magnetic moment norm of a permanent magnet. The models have been tested using an optical reference system for position and orientation estimation. Initial results are ambiguous and further testing is necessary. One conclusion is that the model using the magnetic moment vector as orientation parametrization is less sensitive to the accuracy of the initial guesses of the filter recursions and also less sensitive to possible model errors.

    A mathematical result of the possibility of using a non stationary sensor network to track the magnet is also given.

  • 32.
    Athanasiou, Vasileios
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för radiologiska vetenskaper. Linköpings universitet, Hälsouniversitetet.
    Estimation and modelling of fMRI BOLD response2014Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    One of the current topics of research in neuroimaging techniques is related to explaining and modelling the Blood Oxygen Level Dependent (BOLD) responses. BOLD responses are estimated by processing functional Magnetic Resonance Imaging (fMRI) data. BOLD responses are caused by hemodynamic responses to neural activity which alter the levels of blood oxygenation at local brain regions. The main aims of the current thesis were to i) develop and examine methods regarding BOLD response estimation from the visual cortex and the frontal cortex of human brain and to ii) develop a model in order to explain the physiological mechanisms which cause the estimated BOLD responses.

    In order to satisfy the main aims, fMRI data were provided by the Center of Medical Imaging and Visualization (CMIV). The provided fMRI data consist of fMRI brain measurements of twelve healthy human subjects who were subjected to visual stimulation. By processing the fMRI data, Regions Of Interest (ROIs) were extracted at the anatomical sites of the visual cortex and the frontal cortex. Afterwards, the fMRI data were manipulated in order to extract BOLD responses from the visual cortex and the frontal cortex. Various methods were developed and compared in terms of which technique provided well representative BOLD responses.       

    Subsequently, a model was developed by using software Wolfram Mathematica 9 in order to explain the physiological mechanisms of the estimated BOLD responses at the visual and the frontal cortex. The model aimed to solve for oxygen concentration in blood plasma as blood flows from the arterial part to the venous part of the blood circulation system through a capillary. Oxygen outward diffusion through the capillary wall and oxygen concentration at the extravascular environment were modelled as well. Blood plasma oxygen concentration was turned into hemoglobin oxygen saturation (Sa ) through hemoglobin oxygen dissociation curve and Henry’s law for gases. As a result, the Sa  was estimated through modelling for oxygen concentration in blood plasma. Finally, the developed model ended to a system with input the fractional change of Cerebral Blood Flow (CBF) velocity and Cerebral Metabolic Rate of Oxygen (CMR ) and as output a proportional signal to the BOLD response. By simulating for different scenarios of fractional changes of CBF velocity and CMR  and by comparing the resulted BOLD responses to the estimated ones, it was attempted to explain for the physiological mechanisms which caused the BOLD responses at the anatomical sites of the visual and frontal cortex.

  • 33. Augustine, Robin
    Near-field dosimetry for the millimeter-wave exposure of human cells in vitro2012Inngår i: Bioelectromagnetics, ISSN 0197-8462, E-ISSN 1521-186X, 55-64 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Due to the expected mass deployment of millimeter-wave wireless technologies, thresholds of potential millimeter-wave-induced biological and health effects should be carefully assessed. The main purpose of this study is to propose, optimize, and characterize a near-field exposure configuration allowing illumination of cells in vitro at 60 GHz with power densities up to several tens of mW/cm(2) . Positioning of a tissue culture plate containing cells has been optimized in the near-field of a standard horn antenna operating at 60 GHz. The optimal position corresponds to the maximal mean-to-peak specific absorption rate (SAR) ratio over the cell monolayer, allowing the achievement of power densities up to 50 mW/cm(2) at least. Three complementary parameters have been determined and analyzed for the exposed cells, namely the power density, SAR, and temperature dynamics. The incident power density and SAR have been computed using the finite-difference time-domain (FDTD) method. The temperature dynamics at different locations inside the culture medium are measured and analyzed for various power densities. Local SAR, determined based on the initial rate of temperature rise, is in a good agreement with the computed SAR (maximal difference of 5%). For the optimized exposure setup configuration, 73% of cells are located within the ±3 dB region with respect to the average SAR. It is shown that under the considered exposure conditions, the maximal power density, local SAR, and temperature increments equal 57 mW/cm(2) , 1.4 kW/kg, and 6 °C, respectively, for the radiated power of 425 mW.

  • 34.
    Balkanyi, Laszlo
    et al.
    European Centre for Disease Prevention and Control, Stockholm, Sweden.
    Schulz, Stefan
    Medizinische Universität Graz, Austria and Freiburg University Medical Center, Freiburg, Germany.
    Cornet, Ronald
    Linköpings universitet, Institutionen för medicinsk teknik, Medicinsk informatik. Linköpings universitet, Tekniska högskolan.
    Bodenreider, Olivier
    National Library of Medicine, Bethsheda, USA.
    Medical concept representation: the years beyond 2000.2013Inngår i: Proceedings of Studies in Health Technology & Informatics, vol. 192, IOS Press, 2013, Vol. 192, 1011-1011 s.Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This work aims at understanding the state of the art in the broad contextual research area of "medical concept representation". Our data support the general understanding that the focus of research has moved toward medical ontologies, which we interpret as a paradigm shift. Both the opinion of socially active groups of researchers and changes in bibliometric data since 1988 support this opinion. Socially active researchers mention the OBO foundry, SNOMED CT, and the UMLS as anchor activities.

  • 35.
    Baumgarten, Matthias
    et al.
    University of Ulster.
    Guldenring, Daniel
    University of Ulster.
    Nugent, Chris
    University of Ulster.
    Hallberg, Josef
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Embedding self-awareness into objects of daily life: the smart kettle2010Inngår i: 6th International Conference on Intelligent Environments: IE 2010 : Kuala Lumpur; 19 July 2010 - 21 July 2010, Los Alamitos, Calif, 2010, 34-39 s.Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Intelligent Environments on varying scales and for different purposes are slowly becoming a reality. In the near future, global smart world infrastructures will become a commodity that will support various activities of daily life at different degrees of realism. Such infrastructures have the potential to offer dedicated, context- and situation-aware information and services by simultaneously providing the next-generation of data collection, execution and service provisioning layers. One key aspect of this vision is the correct monitoring and understanding of how people interact with their environment; how they can actually benefit from the added intelligence; and finally how future services can be improved or better personalized to enhance human environment interaction as a whole. This level of intelligence is of particular relevance in the health and social care domain where person-centric services can be deployed to assist or even enable a person in performing activities of daily living. This paper discusses the concept of embedded self-aware profiles for smart devices that can be used to gain a deeper contextual understanding of their use and also discusses the emergence of a general model of Ambient Intelligence that is based on the collective existence and behavior of such smart devices. Although generic in principle, the proposed concepts have been exemplified by a distinct use case, namely a smart kettle.

  • 36. Belfrage, Sara
    Without informed consent2013Inngår i: Moral, Ethical, and Social Dilemmas in the Age of Technology: Theories and Practice, IGI Global, 2013, 291-305 s.Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    The requirement of always obtaining participants' informed consent in research with human subjects cannot always be met, for a variety of reasons. This paper describes and categorises research situations where informed consent is unobtainable. Some of these kinds of situations, common in biomedicine and psychology, have been previously discussed, whereas others, for example, those more prevalent in infrastructure research, introduce new perspectives. The advancement of new technology may lead to an increase in research of these kinds. The paper also provides a review of methods intended to compensate for lack of consent, and their applicability and usefulness for the different categories of situations are discussed. The aim of this is to provide insights into one important aspect of the question of permitting research without informed consent, namely, how well that which informed consent is meant to safeguard can be achieved by other means.

  • 37. Bergström, Mattias
    et al.
    Ericson, Åsa
    Larsson, Madelene
    Nergård, Henrik
    Larsson, Tobias
    Luleå Technical University.
    Renström, Boo
    Needs as a basis for design rationale2008Inngår i: / [ed] Dorian Marjanovic, Mario Storga, Neven Pavkovic, Nenad Bojcetic, University of Zagreb, Dubrovnik, Croatia: University of Zagreb , 2008Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A basic principle for Needfinding [Faste, 1987; Patnaik & Becker, 1999] is that designers and engineers should interact directly with users to get direct insights into the user domain. Needfinding is not a new phenomena, it is almost forty years ago since the process was adopted at Stanford University’s product design program [Patnaik & Becker, 1999]. As the name, Need-finding, implies, this is an intertwined approach to find needs which are not readily articulated by users. The application of a Needfinding process offers qualitative methods to make those needs visible early on in product development. In fact, the process has become more interesting during recent time, since qualitative methods have gained more acceptance outside the academic realm [ibid.].The word qualitative indicates that what are sought for are qualities such as people’s experiences, what they perceive or interpret into a situation [Miles & Huberman, 1994; Patton, 2002]. Such data is contextually dependent, i.e., it must be generated in the context in which the phenomena occur. Besides context, people’s activities, behaviours and goals are important to observe and learn from. The objectives, for applying Needfinding, are to make the identification of needs and design a seamless effort, as well as an interest to identify opportunities to innovations. Needs last longer than any solution [Patnaik & Becker, 1999], since they are grounded in people’s activities. The solution and product that might meet such needs change over time. One example is how to store computer data, the products which satisfy the need has changed from, e.g., punch cards, magnetic tape, floppy discs [ibid.] to USB-flash memories. A guiding methodology in Needfinding is a flexible process, which is adapted to the task at hand [Kelley, 2001]. Such a process is conveyed in a few basic steps and, builds on a ‘philosophy’ which permeates all activities in order to adapt the process according to the project. Therefore, the designer’s ability to rely on such a process depends on familiarity with a number of methods for observations and interviews, as well as an aptitude for socio-technical skills. Hence, the purpose in this paper is to present and reflect on methods used in a running development project to identify needs in a product development project. This is done to contribute to the advancement of a need driven product development process. The disposition of this paper is as follows. First, our approach in studying the need identification activities is presented. Second, a theoretical frame for need identification and design is presented, i.e., Needfinding [Patnaik & Becker, 1999]. Third, the practice of finding needs is outlined and discussed.

  • 38.
    Bitaraf, Nazanin
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    The electrophysiological response of medial preoptic neurons to hypoxia and development of a system for patch-clamp measurement with full oxygen control2011Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    A stroke is caused by interruption of the blood supply to the brain. Yearly 15 million people around the globe endure a stroke and the costs and suffering for the people involved and the society are immense. The aim of this thesis was to investigate the response to oxygen deprivation in neurons from the medial preoptic nucleus (MPN) that have a high abundance of neuroglobin. The long term goal is to investigate the neuroprotective role of the protein in relation to stroke. Initially, the electrophysiological response of neurons to hypoxic exposure in an open system was assessed with a conventional patch-clamp setup. The first aim was to see how well the conventional system worked and if it needed improvement. Secondly, the MPN had never been investigated regarding oxygen, deprivation; hence the electrophysiological response under hypoxia needed to be investigated. The conventional patch-clamp system only allowed a reduction of the oxygen content to a level of 3-6% but not total control of the cell environment. The medial preoptic neurons showed mainly an increase of their resting membrane potential at hypoxia. The voltage activated Ca2+ and K+ currents displayed a clear attenuation when cells were subjected to hypoxia. Non-L-type Ca2+ channels were affected by hypoxic exposure and one cell indicated participation of Ca2+ activated K+ channels. However, a response could only be seen in approximately fifty percent of the neurons in the open system. This may have been due to the fact that full control of the oxygen around the neurons at hypoxia could not be achieved. A new system with full control of the ambient oxygen had to be developed in order to investigate this. After the conclusions of the first experiments, a system was developed were a labon- a-chip system was combined with the patch-clamp technique. A microfluidic system with a patch-clamp micropipette integrated was combined with optical tweezers for 3D maneuvering of the neurons. The development of patch-clamp in combination with a microfluidic system and optical tweezers allowed for full oxygen control. The experiments showed that the electrophysiological measurements were not affected by the laser when an infrared laser was used. The microfluidic system allowed very good oxygen control reaching levels of 0.5-1.5 % compared to 3-6 % in the open system. In summary, this work suggests that high voltage activated Ca2+ channels, and K+ channels are involved in the hypoxic depolarization of medial preoptic neurons. Full control of ambient oxygen in cell vicinity could be achieved by the combination of microfluidics, patch-clamp and optical tweezers. The results can be used in future studies to better understand the reaction of the brain to oxygen deprivation caused by stroke.

  • 39.
    Bitaraf, Nazanin
    et al.
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Alrifaiy, Ahmed
    Luleå tekniska universitet.
    Druzin, Mikhail
    Umeå University, Department of Integrative Medical Biology, Physiology.
    Ramser, Kerstin
    Development of a multifunctional microfluidic system for studies of nerve cell activity during hypoxic and anoxic conditions2009Inngår i: World Congress on Medical Physics and Biomedical Engineering: September 7 - 12, 2009, Munich, Germany, Berlin: Springer Science+Business Media B.V., 2009, Vol. 8, 176-179 s.Konferansepaper (Fagfellevurdert)
  • 40. Bitaraf, Nazanin
    et al.
    Druzin, Mikhail
    Umeå University, Integrative Medical Biology, Physiology.
    Lindahl, Olof
    Ramser, Kerstin
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Elektrofysiologiska mätningar på MPN-neuroner under hypoxi: ett steg mot profylaktisk behandling av patienter i riskzonen för stroke2010Inngår i: Medicinteknikdagarana 2010, 2010Konferansepaper (Annet vitenskapelig)
  • 41. Bitaraf, Nazanin
    et al.
    Ramser, Kerstin
    Luleå tekniska universitet, Institutionen för system- och rymdteknik, Signaler och system.
    Alrifaiy, Ahmed
    Multipla mätningar på enstaka celler i ett mikroflödessystem2009Konferansepaper (Annet vitenskapelig)
  • 42.
    Bleser, Gabriele
    et al.
    German Research Center for Artificial Intelligence (DFKI), Kaiserslautern, Germany.
    Steffen, Daniel
    German Research Center for Artificial Intelligence (DFKI), Kaiserslautern, Germany.
    Reiss, Attila
    ACTLab, University of Passau, 94032, Passau, Germany.
    Weber, Markus
    German Research Center for Artificial Intelligence (DFKI), Kaiserslautern, Germany.
    Hendeby, Gustaf
    Linköpings universitet, Institutionen för systemteknik, Reglerteknik. Linköpings universitet, Tekniska högskolan.
    Fradet, Laetitia
    Université de Poitiers, 86000, Poitiers, France.
    Personalized Physical Activity Monitoring Using Wearable Sensors2015Inngår i: Smart Health: Open Problems and Future Challenges / [ed] Andreas Holzinger, Carsten Röcker, Martina Ziefle, Springer International Publishing , 2015, 99-124 s.Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    It is a well-known fact that exercising helps people improve their overall well-being; both physiological and psychological health. Regular moderate physical activity improves the risk of disease progression, improves the chances for successful rehabilitation, and lowers the levels of stress hormones. Physical fitness can be categorized in cardiovascular fitness, and muscular strength and endurance. A proper balance between aerobic activities and strength exercises are important to maximize the positive effects. This balance is not always easily obtained, so assistance tools are important. Hence, ambient assisted living (AAL) systems that support and motivate balanced training are desirable. This chapter presents methods to provide this, focusing on the methodologies and concepts implemented by the authors in the physical activity monitoring for aging people (PAMAP) platform. The chapter sets the stage for an architecture to provide personalized activity monitoring using a network of wearable sensors, mainly inertial measurement units (IMU). The main focus is then to describe how to do this in a personalizable way: (1) monitoring to provide an estimate of aerobic activities performed, for which a boosting based method to determine activity type, intensity, frequency, and duration is given; (2) supervise and coach strength activities. Here, methodologies are described for obtaining the parameters needed to provide real-time useful feedback to the user about how to exercise safely using the right technique.

  • 43.
    Blom, Hans
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Cellens fysik. KTH, Centra, Science for Life Laboratory, SciLifeLab.
    Brismar, Hjalmar
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Cellens fysik. KTH, Centra, Science for Life Laboratory, SciLifeLab.
    STED microscopy: increased resolution for medical research?2014Inngår i: Journal of Internal Medicine, ISSN 0954-6820, E-ISSN 1365-2796, Vol. 276, nr 6, 560-578 s.Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Optical imaging is crucial for addressing fundamental problems in all areas of life science. With the use of confocal and two-photon fluorescence microscopy, complex dynamic structures and functions in a plethora of tissue and cell types have been visualized. However, the resolution of classical' optical imaging methods is poor due to the diffraction limit and does not allow resolution of the cellular microcosmos. On the other hand, the novel stimulated emission depletion (STED) microscopy technique, because of its targeted on/off-switching of fluorescence, is not hampered by a diffraction-limited resolution barrier. STED microscopy can therefore provide much sharper images, permitting nanoscale visualization by sequential imaging of individual-labelled biomolecules, which should allow previous findings to be reinvestigated and provide novel information. The aim of this review is to highlight promising developments in and applications of STED microscopy and their impact on unresolved issues in biomedical science.

  • 44.
    Brantefors, Per
    Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik. Karolinska Institutet, Department of Clinical Neuroscience.
    Dynamic fMRI brain connectivity: A study of the brain’s large-scale network dynamics2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Approximately 20% of the body’s energy consumption is ongoingly consumed by the brain, where the main part is due to the neural activity, which is only increased slightly when doing a demanding task. This ongoingly neural activity are studied with the so called resting-state fMRI, which mean that the neural activity in the brain is measured for participants with no specific task. These studies have been useful to understand the neural function and how the neural networks are constructed and cooperate. This have also been helpful in several clinical research, for example have differences been identified between bipolar disorder and major depressive disorder. Recent research has focused on temporal properties of the ongoing activity and it is well known that neural activity occurs in bursts. In this study, resting-state fMRI data and temporal graph theory is used to develop a point based method (PBM) to quantify these bursts at a nodal level. By doing this, the bursty pattern can be further investigated and the nodes showing the most bursty pattern (i.e hubs) can be identified. The method developed shows a robustness regarding several different aspects. In the method is two different variance threshold algorithms suggested. One local variance threshold (LVT) based on the individual variance of the edge time-series and one global variance threshold (GVT) based on the variance of all edges time-series, where the GVT shows the highest robustness. However, the choice of threshold needs to be adapted for the aims of the current study. Finally, this method ends up in a new measure to quantify this bursty pattern named bursty centrality. The derived temporal graph theoretical measure was correlated with traditional static graph properties used in resting state and showed a low but significant correlation. By applying this method on resting-state fMRI data for 32 young adults was it possible to identify regions of the brain that showed the most dynamic properties, these regions differed between the two thresholding algorithms

  • 45.
    Broomé, Michael
    et al.
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinsk bildteknik.
    Frenckner, Björn
    Broman, Mikaeö
    Bjällmark, Anna
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinsk bildteknik.
    Recirculation during veno-venous extra-corporeal membrane oxygenation: a simulation study2015Inngår i: International Journal of Artificial Organs, ISSN 0391-3988, E-ISSN 1724-6040, Vol. 38, nr 1, 23-30 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    PURPOSE:

    Veno-venous ECMO is indicated in reversible life-threatening respiratory failure without life-threatening circulatory failure. Recirculation of oxygenated blood in the ECMO circuit decreases efficiency of patient oxygen delivery but is difficult to measure. We seek to identify and quantify some of the factors responsible for recirculation in a simulation model and compare with clinical data.

    METHODS:

    A closed-loop real-time simulation model of the cardiovascular system has been developed. ECMO is simulated with a fixed flow pump 0 to 5 l/min with various cannulation sites - 1) right atrium to inferior vena cava, 2) inferior vena cava to right atrium, and 3) superior+inferior vena cava to right atrium. Simulations are compared to data from a retrospective cohort of 11 consecutive adult veno-venous ECMO patients in our department.

    RESULTS:

    Recirculation increases with increasing ECMO-flow, decreases with increasing cardiac output, and is highly dependent on choice of cannulation sites. A more peripheral drainage site decreases recirculation substantially.

    CONCLUSIONS:

    Simulations suggest that recirculation is a significant clinical problem in veno-venous ECMO in agreement with clinical data. Due to the difficulties in measuring recirculation and interpretation of the venous oxygen saturation in the ECMO drainage blood, flow settings and cannula positioning should rather be optimized with help of arterial oxygenation parameters. Simulation may be useful in quantification and understanding of recirculation in VV-ECMO.

  • 46.
    Broomé, Michael
    et al.
    KTH, Medicinsk bildteknik.
    Frenckner, Björn
    ECMO Department, Karolinska University Hospital, Stockholm.
    Broman, Mikaeö
    ECMO Department, Karolinska University Hospital, Stockholm.
    Bjällmark, Anna
    KTH, Medicinsk bildteknik.
    Recirculation during veno-venous extra-corporeal membrane oxygenation: A simulation study2015Inngår i: International Journal of Artificial Organs, ISSN 0391-3988, E-ISSN 1724-6040, Vol. 38, nr 1, 23-30 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    PURPOSE:

    Veno-venous ECMO is indicated in reversible life-threatening respiratory failure without life-threatening circulatory failure. Recirculation of oxygenated blood in the ECMO circuit decreases efficiency of patient oxygen delivery but is difficult to measure. We seek to identify and quantify some of the factors responsible for recirculation in a simulation model and compare with clinical data.

    METHODS:

    A closed-loop real-time simulation model of the cardiovascular system has been developed. ECMO is simulated with a fixed flow pump 0 to 5 l/min with various cannulation sites - 1) right atrium to inferior vena cava, 2) inferior vena cava to right atrium, and 3) superior+inferior vena cava to right atrium. Simulations are compared to data from a retrospective cohort of 11 consecutive adult veno-venous ECMO patients in our department.

    RESULTS:

    Recirculation increases with increasing ECMO-flow, decreases with increasing cardiac output, and is highly dependent on choice of cannulation sites. A more peripheral drainage site decreases recirculation substantially.

    CONCLUSIONS:

    Simulations suggest that recirculation is a significant clinical problem in veno-venous ECMO in agreement with clinical data. Due to the difficulties in measuring recirculation and interpretation of the venous oxygen saturation in the ECMO drainage blood, flow settings and cannula positioning should rather be optimized with help of arterial oxygenation parameters. Simulation may be useful in quantification and understanding of recirculation in VV-ECMO.

  • 47. Brown, Shannon
    et al.
    Ortiz-Catalan, Max
    Petersson, Joel
    Rodby, Kristian
    Seoane, Fernando
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Data- och elektroteknik. University of Borås, Sweden.
    Intarsia-Sensorized Band and Textrodes for Real-Time Myoelectric Pattern Recognition2016Inngår i: Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS / [ed] Patton, J Barbieri, R Ji, J Jabbari, E Dokos, S Mukkamala, R Guiraud, D Jovanov, E Dhaher, Y Panescu, D Vangils, M Wheeler, B Dhawan, AP, Institute of Electrical and Electronics Engineers (IEEE), 2016, 6074-6077 s., 7592114Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Surface Electromyography (sEMG) has applications in prosthetics, diagnostics and neuromuscular rehabilitation. Self-adhesive Ag/AgCl are the electrodes preferentially used to capture sEMG in short-term studies, however their long-term application is limited. In this study we designed and evaluated a fully integrated smart textile band with electrical connecting tracks knitted with intarsia techniques and knitted textile electrodes. Real-time myoelectric pattern recognition for motor volition and signal-to-noise ratio (SNR) were used to compare its sensing performance versus the conventional Ag-AgCl electrodes. After a comprehending measurement and performance comparison of the sEMG recordings, no significant differences were found between the textile and the Ag-AgCl electrodes in SNR and prediction accuracy obtained from pattern recognition classifiers.

  • 48.
    Budde, Kiran Kumar
    Linköpings universitet, Institutionen för systemteknik, Datorseende.
    A Matlab Toolbox for fMRI Data Analysis: Detection, Estimation and Brain Connectivity2012Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    Functional Magnetic Resonance Imaging (fMRI) is one of the best techniques for neuroimaging and has revolutionized the way to understand the brain functions. It measures the changes in the blood oxygen level-dependent (BOLD) signal which is related to the neuronal activity. Complexity of the data, presence of different types of noises and the massive amount of data makes the fMRI data analysis a challenging one. It demands efficient signal processing and statistical analysis methods.  The inference of the analysis is used by the physicians, neurologists and researchers for better understanding of the brain functions.

         The purpose of this study is to design a toolbox for fMRI data analysis. It includes methods to detect the brain activity maps, estimation of the hemodynamic response (HDR) and the connectivity of the brain structures. This toolbox provides methods for detection of activated brain regions measured with Bayesian estimator. Results are compared with the conventional methods such as t-test, ordinary least squares (OLS) and weighted least squares (WLS). Brain activation and HDR are estimated with linear adaptive model and nonlinear method based on radial basis function (RBF) neural network. Nonlinear autoregressive with exogenous inputs (NARX) neural network is developed to model the dynamics of the fMRI data.  This toolbox also provides methods to brain connectivity such as functional connectivity and effective connectivity.  These methods are examined on simulated and real fMRI datasets.

  • 49.
    Buendia, Ruben
    et al.
    University of Borås, Sweden.
    bogonez-franco, Paco
    Technical University of Catalonia.
    Nescolarde, Lexa
    Technical University of Catalonia.
    Seoane, Fernando
    KTH, Skolan för teknik och hälsa (STH), Medicinska sensorer, signaler och system (MSSS).
    Influence of electrode mismatch on Cole parameter estimation from Total Right Side Electrical Bioimpedance Spectroscopy measurements2012Inngår i: Medical Engineering and Physics, ISSN 1350-4533, E-ISSN 1873-4030, Vol. 34, nr 7, 1024-1028 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Applications based on measurements of Electrical Bioimpedance (EBI) spectroscopy analysis, like assessment of body composition, have proliferated in the past years. Currently Body Composition Assessment (BCA) based in Bioimpedance Spectroscopy (BIS) analysis relays on an accurate estimation of the Cole parameters R-0 and R-infinity. A recent study by Bogonez-Franco et al. has proposed electrode mismatch as source of remarkable artefacts in BIS measurements. Using Total Right Side BIS measurements from the aforementioned study, this work has focused on the influence of electrode mismatch on the estimation of R-0 and R-infinity using the Non-Linear Least Square curve fitting technique on the modulus of the impedance. The results show that electrode mismatch on the voltage sensing electrodes produces an overestimation of the impedance spectrum leading to a wrong estimation of the parameters R-0 and R-infinity, and consequently obtaining values around 4% larger that the values obtained from BIS without electrode mismatch. The specific key factors behind electrode mismatch or its influence on the analysis of single and spectroscopy measurements have not been investigated yet, no compensation or correction technique is available to overcome the deviation produced on the EBI measurement. Since textile-enabled EBI applications using dry textrodes, i.e. textile electrodes with dry skin-electrode interfaces and potentially large values of electrode polarization impedance are more prone to produce electrode mismatch, the lack of a correction or compensation technique might hinder the proliferation of textile-enabled EBI applications for personalized healthcare monitoring.

  • 50.
    Bujtar, Peter
    et al.
    Southern General Hospital, Glasgow.
    Simonovics, Janos
    Southern General Hospital, Glasgow.
    Koptyug, Andrey
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Avdelningen för ekoteknik och hållbart byggande.
    George, Sandor
    Southern General Hospital, Glasgow.
    Varadi, Karoly
    Southern General Hospital, Glasgow.
    Emerging manufacturing bioengineering technologies 2: Scaffold designing experiment using titanium scaffolds2014Inngår i: British Journal of Oral & Maxillofacial Surgery, ISSN 0266-4356, E-ISSN 1532-1940, Vol. 52, nr 8, e60-e61 s.Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Substantial volume defects of the head and neck oftenrequire customized solutions to improve quality of life likefree flap transfers.Titanium and its alloys are versatile materialsproviding the feature of osteointegration. The conditionswhich facilitate the deposition of lamellar bone are underextensive research. Our project aimed to determine whethertitanium can function as a scaffold - unlike simple plates - toenhance bone regeneration for load bearing structures. Thereaction of stem cells to scaffolds with varying stiffness willbe presented.Additive manufacturing were used to produce a variety ofscaffolds to optimize titanium structures. Electric beam melting(EBM) manufacturing allowed us to optimize the elasticmodulus (Young) of the titanium to match with cadaveric 

    bone from a previous project. Multidirectional mechanicaltests were performed on the various designs of titanium cellstructures (n=80). The predictability and quality of manufacturingwas assessed statistically and also with scanningelectron microscope (SEM).The results demonstrated structures matching the mechanicalproperties of bone and even anisotropy as our resultssuggest 3GPa elasticity. This allows the possibility to buildregenerating bone with predictable properties. In addition,predictable patterning - unlike etching and sandblasting - ofmicroscopic (nano) features found to be significant and nonhomogenous simple repetitive patterns provide better cellularresponse.The benefit that tissue engineering techniques offer isdecreased morbidity, relative independence from donor site,with a highly specific and customized shape. Titanium basedreconstruction constructs seems to offer an alternative futurefor bony reconstruction.

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