Extracting heart rate dependent electrocardiogram templates for a body emulator environment

Abstract. Medical device and analysis method developments often include tests on humans, which are expensive, time consuming, and sometimes even dangerous. In order to perform human tests, special safety conditions and ethical and legal requirements must be taken into account. Emulators that can emulate the physiological functions of the human body could solve these difficulties. In this study, the heart rate depended electrocardiogram templates for this kind of an emulator were extracted. The real-life electrocardiogram preprocessing included a high-pass filter and a Savitzky-Golay filter. A beat detection algorithm was developed to detect QRS complexes in the signals and classify beat artefacts based on the RR interval sequences and two adaptive thresholds. Heart rate levels were detected using the K-means clustering technique. Vectorcardiogram signals were converted from the electrocardiogram signals using the inverse Dower’s transformation matrix, and vectorcardiogram templates were extracted to the respective heart rate levels. Finally, a graphical user interface was created for the mentioned methods. The developed beat detection algorithm was tested with the MIT-BIH Arrhythmia Database and the comparison was made with the state-of-the-art algorithms. The beat detection algorithm resulted the sensitivity of 99.77 \%, precision of 99.65 \%, and detection error rate of 0.58 \%. Based on the results, the proposed methods and extracted vectorcardiogram templates were successful.Sykkeestä riippuvien elektrokardiogrammimallien poiminta kehoemulaattoriympäristöön. Tiivistelmä. Lääketieteellisten laitteiden ja analyysimenetelmien kehitystyö sisältää usein ihmisille suoritettavia testejä, jotka ovat kalliita, aikaa vieviä ja joskus jopa vaarallisia. Ihmiskokeiden toteuttamiseksi on otettava huomioon erityisiä turvallisuusehtoja, sekä eettisiä ja laillisia vaatimuksia. Emulaattorit, jotka pystyvät jäljittelemään ihmiskehon fysiologisia toimintoja, voivat olla ratkaisu näihin ongelmiin. Tässä tutkimuksessa sykkeestä riippuvia elektrokardiogrammimalleja poimittiin tämän tyyppiselle emulaattorille. Tosielämän elektrokardiogrammisignaalien esikäsittely sisälsi ylipäästösuodattimen ja Savitzky-Golay suodattimen. Sydämen lyöntien tunnistussalgoritmi kehitettiin tunnistamaan QRS-komplekseja signaaleista ja luokittelemaan lyöntiartefakteja RR-intervallisekvenssien ja kahden adaptiivisen kynnysarvon perusteella. Syketasot tunnistettiin käyttämällä K-means klusterointitekniikkaa. Vektorikardiogrammisignaalit muunnettiin elektrokardiogrammisignaaleista käyttämällä käänteistä Dowerin muunnosmatriisia ja vektorikardiogrammimallit poimittiin vastaaville syketasoille. Lopuksi luotiin graafnen käyttöliittymä mainituille menetelmille. Kehitetty lyöntien tunnistusalgoritmi testattiin MIT-BIH Arrhythmia Database-tietokannalla ja vertailu suoritettiin vastaavien algoritmien kanssa. Algoritmi suoriutui 99,77 % herkkyydellä, 99,65 % spesifsyydellä ja 0,58 % virheprosentilla. Tulosten perusteella ehdotetut menetelmät ja poimitut vektorikardiogrammimallit olivat onnistuneita

Steel Sandwich Panels in Marine Applications

Steel sandwich panels welded by laser can offer 30-50 % weight savings compared to the conventional steel structures. Helsinki University of Technology/Ship Laboratory has done active research during the past 10 years on various topics related to the laser welded steel sandwich panels. The work carried out includes development of design formulations for the ultimate and impact strength, analysis of fatigue strength for the joints, and development of solutions to improve the behaviour under fire. A number of research projects both at the national and European level have been ongoing. In the paper, a summary of the marine applications, main benefits and problem areas of the panels as well as available design tools are given. A case study for weight and cost optimisation of a hoistable cardeck is also presented proving some of the described benefits of all steel sandwich panels

Towards an evidence-based probabilistic risk model for ship-grounding accidents

AbstractMost of the risk models for ship-grounding accidents do not fully utilize available evidence, since it is based on accident statistics and expert opinions. The major issue with such kinds of models is their limitation in supporting the process of risk-management with respect to grounding accidents, since they do not reflect the reality to the extent required. This paper presents an evidence-based and expert-supported approach to structure a model assessing the probability of ship-grounding accidents, to make it more suitable for risk-management purposes. The approach focuses on using evidential data of ship-grounding accidents extracted from the actual accident and incident reports as well as the judgement elicited from the experts regarding the links and probabilities not supported by the reports. The developed probabilistic model gathers, in a causal fashion, the evidential contributing factors in ship-grounding accidents. The outcome of the model is the probability of a ship-grounding accident given the prior and posterior probabilities of the contributing factors. Moreover, the uncertainties associated with the elements of the model are clearly communicated to the end-user adopting a concept of strength-of-knowledge. The model can be used to suggest proper risk-control-measures to mitigate the risk. By running uncertainty and sensitivity analyses of the model, the areas that need more research for making educated decisions are defined. The model suggests the high-level critical parameters that need proper control measures are complexity of waterways, traffic situations encountered, and off-coursed ships. The critical area that calls for more investigation is the onboard presence of a sea-pilot

An analysis of ship escort and convoy operations in ice conditions

Winter navigation is a complex but common operation in the Northern Baltic Sea areas. In Finnish waters, the safety of the wintertime maritime transportation system is managed through the Finnish–Swedish winter navigation system. This system results in different operational modes of ship navigation, with vessels either navigating independently or under icebreaker assistance. A recent risk analysis indicates that during icebreaker assistance, convoys operations are among the most hazardous, with convoy collisions the most important risk events. While the accident likelihood per exposure time is rather low, accidents occur almost every winter. Even though these typically lead to less serious consequences, accidents leading to ship loss and oil pollution have occurred and may occur in the future. One aspect of ship convoy navigation in ice conditions is the distance kept between the icebreaker and the ships in the convoy, a form of the well-known ship domain concept. While operational experience naturally is a valuable source of information for decision making about the distance of navigation in convoys, systematic analyses are lacking. The aim of this paper is to investigate selected operational aspects of convoy navigation in ice conditions in the Finnish waters of the Gulf of Finland, based on data of the Automatic Identification System and sea ice hindcast data. Focus is on obtaining qualitative and quantitative knowledge concerning distances between vessels in escort and convoy operations and the respective transit speeds, conditional to ice conditions. Such empirical knowledge can support operational decision making, contributing to wintertime maritime safety.Peer reviewe

Estimating Operability of Ships in Ridged Ice Fields

A method for estimating ship's resistance caused by sea ice ridge keels is revised and used as a part of a method for predicting performance of ships in ridged ice conditions. The resistance method is based on a continuum plasticity model of ridge rubble and is simple to compute. The performance prediction method combines deterministic simulations of ship motion with probabilistic modelling of ridged ice fields. Performance estimates given by the model are distribution of attainable mean speeds for given ice conditions and probability of the ship being able to operate independently. A comprehensive sensitivity analysis was performed to gain insight into the model and identify possible problematic parameters. The sensitivity analysis covered both the ice conditions and modelling assumptions. Two data-sets were used to test the simulation method. One set included the depth profile of sea ice, machinery data and the speed of a ship operating in ridged ice. The resistance method was able to predict the meanspeed over 3km well. The second data-set consisted of a history of ship's speeds and positions from AIS data and ice conditions estimated by a numerical ice model HELMI, developed in the Finnish Meteorological Institute. Observed mean speeds were mostly well within the distributions of mean speeds simulated by the transit simulation model. Predictions of independent operation were also promising.Peer reviewe

Poor neural and perceptual phoneme discrimination during acoustic variation in dyslexia

Whereas natural acoustic variation in speech does not compromise phoneme discrimination in healthy adults, it was hypothesized to be a challenge for developmental dyslexics. We investigated dyslexics’ neural and perceptual discrimination of native language phonemes during acoustic variation. Dyslexics and non-dyslexics heard /æ/ and /i/ phonemes in a context with fo variation and then in a context without it. Mismatch negativity (MMN) and P3a responses to phoneme changes were recorded with electroencephalogram to compare groups during ignore and attentive listening. perceptual phoneme discrimination in the variable context was evaluated with hit-ratios and reaction times. MMN/N2bs were diminished in dyslexics in the variable context. Hit-ratios were smaller in dyslexics than controls. MMNs did not differ between groups in the context without variation. These results suggest that even distinctive vowels are challenging to discriminate for dyslexics when the context resembles natural variability of speech. This most likely reflects poor categorical perception of phonemes in dyslexics. Difficulties to detect linguistically relevant invariant information during acoustic variation in speech may contribute to dyslexics’ deficits in forming native language phoneme representations during infancy. Future studies should acknowledge that simple experimental paradigms with repetitive stimuli can be insensitive to dyslexics’ speech processing deficits.Peer reviewe

Olemassa olevat virtuaalitodellisuuskävelyalustat, niiden erot ja toimintaperiaatteet

Tiivistelmä. Tässä työssä perehdyttiin eri virtuaalitodellisuuskävelyalustoihin ja niiden eroihin, sekä käytiin läpi niiden yleisimmät toimintaperiaatteet. Käsiteltävistä kävelyalustoista tehtiin 3D-mallinnukset Autodesk Fusion 360 -ohjelmalla. Työssä käsiteltiin myös virtuaalitodellisuudesta aiheutuvaa pahoinvointia sekä virtuaalitodellisuuden historiaa ja taloudellista tilannetta.Existing virtual reality walking platforms, their differences and how they work. Abstract. This work is study of virtual reality treadmills and their differences. It also includes overview of principles how these treadmills work. The treadmills were 3D modelled using Autodesk Fusion 360 software. The work also includes virtual reality nausea and the history and financial situation of virtual reality

Suicide and depression in former contact sports participants: population-based cohort study, systematic review, and meta-analysis

Background: Former participants in sports characterised by low intensity repetitive head impact appear to have elevated rates of later dementia, but links with other psychological health outcomes such as depression and suicide are uncertain. We quantified the occurrence of these endpoints in former contact sports athletes against general population controls using new data from a cohort study and a meta-analysis. Methods: The cohort study comprised 2004 retired male athletes, who had competed internationally as amateurs for Finland across a range of sports, and 1385 general population controls. All study members were linked to mortality and hospitalisation registries. In the PROSPERO-registered systematic review (CRD42022352780), we searched PubMed and Embase to October 31 2022 for cohort studies that reported standard estimates of association and precision. Study-specific estimates were aggregated in a random-effect meta-analysis. The Newcastle-Ottawa Scale was used to appraise the quality of each study. Findings: In survival analyses of the Finnish cohort data, former boxers (depression: hazard ratio 1.43 [95% CI 0.73, 2.78]; suicide: 1.75 [0.64, 4.38]), Olympic-style wrestlers (depression: 0.94 [0.44, 2.00]; suicide: 1.60 [0.64, 3.99]), and soccer players (depression: 0.62 [0.26, 1.48]; suicide: 0.50 [0.11, 2.16]) did not have statistically higher rates of major depressive disorder or suicide at follow-up relative to controls. In the systematic review, 7 cohort studies met inclusion criteria. After aggregating results with the Finnish cohort, retired soccer players appeared to have a lower risk of depression (summary risk ratio: 0.71 [0.54, 0.93]) relative to general population controls, while the rate of suicide was statistically the same across groups (0.70 [0.40, 1.23]). Past participation in American football seemed to be associated with some protection against suicide (0.58 [0.43, 0.80]) but there were insufficient studies of depression in this sport to facilitate aggregation. The aggregation of results from the soccer and American football studies showed directionally consistent relationships and there was no indication of inter-study heterogeneity (I2 = 0%). Interpretation: Based on a small cluster of studies exclusively comprising men, retired soccer players had a lower rate of later depression and former American football players had a lower risk of suicide relative to comparator groups. Whether these findings are generalisable to women requires testing. Funding: The preparation of this manuscript was unfunded

Trends and risk factors of stillbirths and neonatal deaths in Eastern Uganda (1982-2011): a cross-sectional, population-based study.

: To identify mortality trends and risk factors associated with stillbirths and neonatal deaths 1982-2011. : Population-based cross-sectional study based on reported pregnancy history in Iganga-Mayuge Health and Demographic Surveillance Site (HDSS) in Uganda. A pregnancy history survey was conducted among women aged 15-49 years living in the HDSS during May-July 2011 (n = 10 540). Time trends were analysed with cubic splines and linear regression. Potential risk factors were examined with multilevel logistic regression with adjusted odds ratios (AOR) and 95% confidence intervals (CI). : 34 073 births from 1982 to 2011 were analysed. The annual rate of decrease was 0.9% for stillbirths and 1.8% for neonatal mortality. Stillbirths were associated with several risk factors: multiple births (AOR 2.57, CI 1.66-3.99), previous adverse outcome (AOR 6.16, CI 4.26-8.88) and grand multiparity among 35- to 49-year-olds (AOR 1.97, CI 1.32-2.89). Neonatal deaths were associated with multiple births (AOR 6.16, CI 4.80-7.92) and advanced maternal age linked with parity of 1-4 (AOR 2.34, CI 1.28-4.25) and grand multiparity (AOR 1.44, CI 1.09-1.90). Education, marital status and household wealth were not associated with the outcomes. : The slow decline in mortality rates and easily identifiable risk factors calls for improving quality of care at birth and a rethinking of how to address obstetric risks, potentially a revival of the risk approach in antenatal care.<br/