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- Ahlström, Christer, 1977-, et al.
(författare)
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Assessment of Suspected Aortic Stenosis by Auto Mutual Information Analysis of Murmurs
- 2007
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Ingår i: Engineering in Medicine and Biology Society, 2007. EMBS 2007. - 9781424407873 ; , s. 1945-1948
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Konferensbidrag (refereegranskat)abstract
- Mild sclerotic thickening of the aortic valve affects 25% of the population, and the condition causes aortic valve stenosis (AS) in 2% of adults above 65 years. Echocardiography is today the clinical standard for assessing AS. However, a cost effective and uncomplicated technique that can be used for decision support in the primary health care would be of great value. In this study, recorded phonocardiographic signals were analyzed using the first local minimum of the auto mutual information (AMI) function. The AMI method measures the complexity in the sound signal, which is related to the amount of turbulence in the blood flow and thus to the severity of the stenosis. Two previously developed phonocardiographic methods for assessing AS severity were used for comparison, the murmur energy ratio and the sound spectral averaging technique. Twenty-nine patients with suspected AS were examined with Doppler echocardiography. The aortic jet velocity was used as a reference of AS severity, and it was found to correlate with the AMI method, the murmur energy ratio and the sound spectral averaging technique with the correlation coefficient R = 0.82, R = 0.73 and R = 0.76, respectively.
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| 2. |
- Silfverskiöld, Stefan, 1964-, et al.
(författare)
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Technology Forecast 2017 - Military Utility of Future Technologies : A Report from Seminars at the Swedish Defence University’s (SEDU) Military-Technology Division
- 2017
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Two technology forecast reports from the Fraunhofer Institute, three reports from the Swedish Defence Research Institute (FOI) and two publications from the Massachusetts Institute of Technology (MIT) have been reviewed by staff at the Military-Technology Division at the Swedish Defence University (SEDU). The task given by the Defence Material Administration (FMV) was to assess the military utility of the given technologies in a time frame to up 2040, from a Swedish Armed Forces (SwAF) perspective.In the review we assessed the military utility of certain technologies as possible contributions to the operational capabilities of the SwAF, based on identified and relevant scenarios. Because a new capability catalogue is under development at the SwAF Headquarters, this report only presents general assessments of the capability impact of the technologies studied.The technologies were grouped into four classes: potentially significant, moderate, negligible, or uncertain military utility.The classification uncertain military utility was given to technologies that are difficult to put in the other three classes, it was not because the technology readiness level (TRL) will not bereached by 2040.The following technologies were assessed to have the potential for significant military utility:- Nanocarbons for photonic applicationsThe following technologies were assessed to have a potential for moderate military utility;- Internet of things (IoT)- Materials and technologies for protection against chemical agentsThe following technologies were assessed to have uncertain military utility;- Post-quantum cryptography- New applications for hyperspectral image analysis for chemical and biological agentsNo technology was found to have negligible military utility.The method used in this technology forecast report was to assign each report to one reviewer in the working group. Firstly, each forecast report was summarized. The Fraunhofer assessment of technical readiness level (TRL) in the time period was held to be correct. Each technology was then put into one or more scenarios that were assessed to be suitable for assessing the military utility as well as indicating any possibilities and drawbacks. Based on a SWOTanalysis, the assessed contributions to the fundamental capabilities, and to the factors DOTMPLFI (Doctrine, Organization, Training, Materiel, Leadership, Personnel, Facilities and Interoperability), were listed. Furthermore, the expected SwAF R&D requirements, to facilitate the introduction of the technology are given. The Military utility was assessed using a model developed by the Military-Technology Division. Finally, conclusions and an overall rating of the potential military utility of each technology were presented.The chosen definition of military utility clearly affects the result of the study. The definition used here (“the military utility of a certain technology is its contribution to the operational capabilities of the SwAF, within identified relevant scenarios”) has been used in our Technology Forecasts since 2013.Our evaluation of the method used shows that there is a risk that assessments can be biased by the participating experts’ presumptions and experience from their own field of research. It should also be stressed that the seven technologies’ potential military utility was assessed within the specific presented scenarios and their possible contribution to operational capabilities within those specific scenarios, not in general. When additional results have been found in the analysis, this is mentioned.The greatest value of the method used is its simplicity, cost effectiveness and that it promotes learning within the working group. The composition of the working group and the methodology used are believed to provide a broad and balanced coverage of the technologies being studied. This report should be seen as an executive summary of the research reports and the intention is to help the SwAF Headquarters to evaluate the military utility of emerging technologies within identified relevant scenarios.Overall, the research reports are considered to be balanced and of high quality in terms of their level of critical analysis regarding technology development. These reports are in line with our task to evaluate the military utility of the emerging technologies.
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| 3. |
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| 4. |
- Ahlström, Christer, 1977-, et al.
(författare)
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Distinguishing Innocent Murmurs from Murmurs caused by Aortic Stenosis by Recurrence Quantification Analysis
- 2006
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Ingår i: ROCEEDINGS OF WORLD ACADEMY OF SCIENCE, ENGINEERING AND TECHNOLOGY, VOL 18. - Canakkale, Turkey : World Academy of Science, Engineering and Technology (W A S E T). ; , s. 40-45
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Konferensbidrag (refereegranskat)abstract
- It is sometimes difficult to differentiate between innocent murmurs and pathological murmurs during auscultation. In these difficult cases, an intelligent stethoscope with decision support abilities would be of great value. In this study, using a dog model, phonocardiographic recordings were obtained from 27 boxer dogs with various degrees of aortic stenosis (AS) severity. As a reference for severity assessment, continuous wave Doppler was used. The data were analyzed with recurrence quantification analysis (RQA) with the aim to find features able to distinguish innocent murmurs from murmurs caused by AS. Four out of eight investigated RQA features showed significant differences between innocent murmurs and pathological murmurs. Using a plain linear discriminant analysis classifier, the best pair of features (recurrence rate and entropy) resulted in a sensitivity of 90% and a specificity of 88%. In conclusion, RQA provide valid features which can be used for differentiation between innocent murmurs and murmurs caused by AS.
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| 5. |
- Ahlström, Christer, 1977-, et al.
(författare)
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Thresholding distance plots using true recurrence points
- 2006
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Ingår i: Acoustics, Speech and Signal Processing, 2006. ICASSP 2006. - : IEEE. - 142440469X ; , s. 688-691
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Konferensbidrag (refereegranskat)abstract
- Recurrence plots (RP) visualize multi-dimensional state spaces and represent the recurrence of states of a system. Recurrence points can be divided into true recurrence points and false recurrence points (also called sojourn points). We introduce the true recurrence point recurrence plot, TRP, a variant of the traditional RP excluding the sojourn points. This is a cleaned up RP free from recurrence points originating from tangential motion, and hence a more robust representation of unstable periodic orbits. The method is demonstrated with three simple systems, a periodic sine wave, a quasi-periodic torus and the x-component of the chaotic Lorenz system
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| 10. |
- Danbolt, Christina, 1946-, et al.
(författare)
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Validation and characterization of the computerized laryngeal analyzer (CLA) technique
- 1999
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Ingår i: Dysphagia (New York. Print). - 0179-051X .- 1432-0460. ; 14:4, s. 191-195
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate the response characteristics of the Computerized Laryngeal Analyzer (CLA) and the validity of the noninvasive CLA method to detect swallowing-induced laryngeal elevation correctly. Two healthy adults and two experimental models were used in the study. The CLA technique identified all swallowing events but was unable to discriminate between swallowing and other movements of the tongue or the neck. The computer program produced a derivated response to a square wave signal. Stepwise bending increments of the sensor displayed a linear amplitude response. The degree of laryngeal elevation could not be estimated with the CLA technique, and it was not possible to draw any reliable conclusions from the recordings as to whether the larynx was moving upward or downward.
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