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  • Lui, Hoi-Shun, et al. (författare)
  • On the matching medium for microwave stroke diagnosis
  • 2019
  • Ingår i: Biomedical Physics and Engineering Express. - 2057-1976. ; 5:4
  • Tidskriftsartikel (refereegranskat)abstract
    • The choice of matching medium can directly affect the amount of power transmitted into and through human bodies, which impacts on the quality of the reconstructed images in microwave-based medical imaging, and thus the diagnosis accuracies. In this paper, the amount of the transmitted and reflected power of multi-layer planar healthy and hemorrhagic stroke brain models under different choices of matching medium are determined. These multi-layer planar brain tissue models are made up of at least 17 tissue layers with realistic dielectric properties. A layer of blood with different thickness is introduced to model the case of hemorrhagic stroke. Our results show that matching medium with low relative permittivity provides better intrinsic contrast between healthy brain and hemorrhagic brain. Analysis on how the reflection coefficient and transmittance vary under different matching medium are included to provide better insights to the findings.
  • Rezaei Aghdam, Sina, 1989-, et al. (författare)
  • Reducing Motion Artifacts in Microwave-Based Hemorrhagic Stroke Detection
  • 2019
  • Ingår i: 13th European Conference on Antennas and Propagation, EuCAP 2019.
  • Konferensbidrag (refereegranskat)abstract
    • The use of microwave technology for brain stroke detection opens up the opportunity for developing low-cost transportable devices which can be employed for rapid and prehospital detection of bleeding in patients with traumatic brain injury. Since the detection relies on changes in the scattering parameters of the tissues during pathological conditions, the movements in head or the antennas can deteriorate the detection accuracy. As a countermeasure to this problem, we introduce a technique for reducing the sensitivity of the detection system to motion artifacts. Via analyzing the scattering from an anatomically accurate model of human brain, we evidence that the channels between different pairs of antennas exhibit significantly different levels of sensitivity to the movement. Using this as a ground truth, we develop a generalized singular value decomposition (GSVD)-based approach for assigning appropriate weights to the channels between different antennas such that the probability of correct bleeding detection is maximized.
  • Rowa, Per, et al. (författare)
  • Automated Malaria Parasite Detection
  • 1977
  • Rapport (övrigt vetenskapligt)abstract
    • <p>A system for malaria parasite detection in thin blood-smears is presented. Sample slides prepared with standard methods are accepted. A low-cost TV-camera mounted on an ordinary microscope with a computer controlled stage is used as a picture sensor. Frames, digitized in windows of 64 x 64 pixels are fed into a special purpose picture processor at normal frame rate (25 frames/sec). In the picture processor measurements are made on the images at high speed. The classification problem is split into different levels each having different characteristics such as different sampling density. Four classes, three of which are different types of malaria parasites, are recognized. As a whole the classification is best labelled as a sequential pattern recognition procedure.</p><p>In its preliminary version the system has been run at a speed comparable to that of a human operator, that is l 500 cells per minute. A test on 80 000 cells gave 25 false negatives out of 283 parasites (9%) and 41 false positives (0.05%).</p>
  • Tomasic, Ivan, et al. (författare)
  • Comparison of publicly available beat detection algorithms performances on the ECGs obtained by a patch ECG device
  • 2019
  • Ingår i: 2019 42nd International Convention on Information and Communication Technology, Electronics and Microelectronics, MIPRO 2019 - Proceedings. - Institute of Electrical and Electronics Engineers Inc.. - 9789532330984 ; s. 275-278
  • Konferensbidrag (refereegranskat)abstract
    • <p>Eight ECG beat detection algorithms, from the PhysioNet's WFDB and Cardiovascular Signal toolboxes, were tested on twenty measurements, obtained by the Savvy patch ECG device, for their accuracy in beat detection. On each subject, one measurement is obtained while sitting and one while running. Each measurement lasted from thirty seconds to one minute. The measurements obtained while running were more challenging for all the algorithms, as most of them almost perfectly detected all the beats on the measurements obtained in sitting position. However, when applied on the measurements obtained while running, all the algorithms have performed with decreased accuracy. Considering overall percentage of the faulty detected peaks, the four best algorithms were jqrs, from the Cardiovascular Signal Toolbox, and ecgpuwave, gqrs, and wqrs, from the WFDB Toolbox, with percentages of faulty detected beats 1.7, 2.3, 2.9, and 3, respectively. </p>
  • Zeng, Xuezhi, 1980-, et al. (författare)
  • Investigation of an ultra wideband noise sensor for health monitoring
  • 2020
  • Ingår i: Sensors. - 1424-8220 .- 1424-3210. ; 20:4
  • Tidskriftsartikel (refereegranskat)abstract
    • Quick on-scene assessment and early intervention is the key to reduce the mortality of stroke and trauma patients, and it is highly desirable to develop ambulance-based diagnostic and monitoring devices in order to provide additional support to the medical personnel. We developed a compact and low cost ultra wideband noise sensor for medical diagnostics and vital sign monitoring in pre-hospital settings. In this work, we demonstrated the functionality of the sensor for respiration and heartbeat monitoring. In the test, metronome was used to manipulate the breathing pattern and the heartbeat rate reference was obtained with a commercial electrocardiogram (ECG) device. With seventeen tests performed for respiration rate detection, sixteen of them were successfully detected. The results also show that it is possible to detect the heartbeat rate accurately with the developed sensor.
  • Capece, Sabrina, et al. (författare)
  • A general strategy for obtaining biodegradable polymer shelled microbubbles as theranostic devices
  • 2013
  • Ingår i: 3 MiCRON EU FP7.
  • Tidskriftsartikel (refereegranskat)abstract
    • <p>Fabrication of multifunctional ultrasound contrast agents (UCAs) has been recently addressed by several research groups. A versatile strategy for the synthesis of UCA precursors in the form of biodegradable vesicles with a biocompatible crosslinked polymer shell is described. Upon ultrasound irradiation, acoustic droplet vaporization transforms such particles into microbubbles behaving as UCAs. This proof of concept entails the features of a potential theranostic microdevice.</p>
  • Fhager, A., et al. (författare)
  • 3D Simulations of Intracerebral Hemorrhage Detection Using Broadband Microwave Technology
  • 2019
  • Ingår i: Sensors. - 1424-8220 .- 1424-3210. ; 19:16
  • Tidskriftsartikel (refereegranskat)abstract
    • Early, preferably prehospital, detection of intracranial bleeding after trauma or stroke would dramatically improve the acute care of these large patient groups. In this paper, we use simulated microwave transmission data to investigate the performance of a machine learning classification algorithm based on subspace distances for the detection of intracranial bleeding. A computational model, consisting of realistic human head models of patients with bleeding, as well as healthy subjects, was inserted in an antenna array model. The Finite-Difference Time-Domain (FDTD) method was then used to generate simulated transmission coefficients between all possible combinations of antenna pairs. These transmission data were used both to train and evaluate the performance of the classification algorithm and to investigate its ability to distinguish patients with versus without intracranial bleeding. We studied how classification results were affected by the number of healthy subjects and patients used to train the algorithm, and in particular, we were interested in investigating how many samples were needed in the training dataset to obtain classification results better than chance. Our results indicated that at least 200 subjects, i.e., 100 each of the healthy subjects and bleeding patients, were needed to obtain classification results consistently better than chance (p &lt; 0.05 using Student's t-test). The results also showed that classification results improved with the number of subjects in the training data. With a sample size that approached 1000 subjects, classifications results characterized as area under the receiver operating curve (AUC) approached 1.0, indicating very high sensitivity and specificity.
  • Forcolin, Fabio, 1991-, et al. (författare)
  • Comparison of outlier heartbeat identification and spectral transformation strategies for deriving heart rate variability indices for drivers at different stages of sleepiness
  • 2018
  • Ingår i: Traffic Injury Prevention. - 1538-957X .- 1538-9588. ; 19, s. S112-S119
  • Tidskriftsartikel (refereegranskat)abstract
    • Objective: Appropriate preprocessing for detecting and removing outlier heartbeats and spectral transformation is essential for deriving heart rate variability (HRV) indices from cardiac monitoring data with high accuracy. The objective of this study is to evaluate agreement between standard preprocessing methods for cardiac monitoring data used to detect outlier heartbeats and perform spectral transformation, in relation to estimating HRV indices for drivers at different stages of sleepiness. Methods: The study analyzed more than 3,500 5-min driving epochs from 76 drivers on a public motorway in Sweden. Electrocardiography (ECG) data were recorded in 3 studies designed to evaluate the physiological differences between awake and sleepy drivers. The Pan-Tompkins algorithm was used for peak detection of heartbeats from ECG data. Two standard methods were used for identifying outlier heartbeats: (1) percentage change (PC), where outliers were defined as interbeat interval deviating &gt; 30% from the mean of the 4 previous intervals, and (2) standard deviation (SD), where outliers were defined as interbeat interval deviating &gt; 4 SD from the mean interval duration in the current epoch. Three standard methods were used for spectral transformation, which is needed for deriving HRV indices in the frequency domain; these methods were (1) the Fourier transform; (2) an autoregressive model; and (3) the Lomb-Scargle periodogram. The preprocessing methods were compared quantitatively and by assessing agreement between estimations of 13 common HRV indices using Bland-Altman plots and paired Student's t-tests. Results: The PC method detected more than 4 times as many outliers (0.28%) than SD (0.065%). Most HRV indices derived using different preprocessing methods exhibited significant systematic (P &lt; .05) and substantial random variations. Conclusions: The standard preprocessing methods for HRV data for outlier heartbeat detection and spectral transformation show low levels of agreement. This finding implies that, prior to designing algorithms for detection of sleepy drivers based on HRV analysis, the impact of different preprocessing methods and combinations thereof on driver sleepiness assessment needs to be studied.
  • Fredén Jansson, Karl-Johan, 1988- (författare)
  • The Balanced Electromagnetic Separation Transducer for Bone Conduction Audiometry and Hearing Rehabilitation
  • 2017
  • Doktorsavhandling (övrigt vetenskapligt)abstract
    • Hearing via air conduction (AC) and bone conduction (BC) are attributed to bethe natural ways of conducting sound to the cochlea. With AC hearing, air pressurevariations are transmitted to the cochlea via the ear canal, whereas with BChearing, sound vibrations are transmitted through the skull bone to the cochlea.Patients with a hearing loss in the cochlea or auditory nerve are commonly rehabilitatedwith conventional AC hearing aids in the ear canal, but also using cochlearimplants. If the pathway for AC sound to reach the cochlea is obstructed, patientscan often benet from bone conduction devices (BCDs). In order to determinethe type and degree of hearing loss, the BC hearing thresholds are measured usinga bone conduction vibrator, and then analyzed together with the AC hearingthresholds for the diagnosis and to suggest an appropriate rehabilitation alternative.The motor unit in conventional BCDs and bone vibrators are known togenerate high amount of distortion at low frequencies where the Balanced ElectromagneticSeparation Transducer (BEST) principle may oer a new era in BChearing rehabilitation and audiometry.This thesis combines two BC hearing related topics, where the rst topic is anevaluation of a new audiometric bone vibrator, Radioear B81, which is assumedto oer more accurate BC hearing threshold measurements. The second topic isrelated to a new type of active transcutaneous BCD, called the Bone ConductionImplant (BCI), which leaves the skin intact by using a wireless solution thatdoes not require a permanent skin penetration. Even though the applications aredierent, both devices use the BEST principle as motor unit in their design.The audiometric bone vibrator Radioear B81 was found to have an improvedperformance at low frequencies where it can produce higher output levels with lessharmonic distortion than the conventional Radioear B71. In a clinical study of therst six patients, the BCI was found as ecient as already commercially availableBCDs, and with the advantage of not needing a skin penetration. In a technicalevaluation of the BCI, it was shown to be a mechanically robust design and totolerate magnetic resonance imaging at 1.5 Tesla.
  • Gil Berrocal, Carlos, 1986-, et al. (författare)
  • Crack monitoring in reinforced concrete beams by distributed optical fiber sensors
  • 2020
  • Ingår i: Structure and Infrastructure Engineering. - 1573-2479 .- 1744-8980. ; In Press
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper investigates the use of distributed optical fiber sensors (DOFS) based on Optical Frequency Domain Reflectometry of Rayleigh backscattering for Structural Health Monitoring purposes in civil engineering structures. More specifically, the results of a series of laboratory experiments aimed at assessing the suitability and accuracy of DOFS for crack monitoring in reinforced concrete members subjected to external loading are reported. The experiments consisted on three-point bending tests of concrete beams, where a polyamide-coated optical fiber sensor was bonded directly onto the surface of an unaltered reinforcement bar and protected by a layer of silicone. The strain measurements obtained by the DOFS system exhibited an accuracy equivalent to that provided by traditional electrical foil gauges. Moreover, the analysis of the high spatial resolution strain profiles provided by the DOFS enabled the effective detection of crack formation. Furthermore, the comparison of the reinforcement strain profiles with measurements from a digital image correlation system revealed that determining the location of cracks and tracking the evolution of the crack width over time were both feasible, with most errors being below +/- 3 cm and +/- 20 mu m, for the crack location and crack width, respectively.
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