Land Assembly for Housing Developments

The ability to identify premature arterial stiffening is of considerable value in the prevention of cardiovascular diseases. The “ageing index” (AGI), which is calculated from the second derivative photoplethysmographic (SDPPG) waveform, has been used as one method for arterial stiffness estimation and the evaluation of cardiovascular ageing. In this study, the new SDPPG analysis algorithm is proposed with optimal filtering and signal normalization in time. The filter parameters were optimized in order to achieve the minimal standard deviation of AGI, which gives more effective differentiation between the levels of arterial stiffness. As a result, the optimal low-pass filter edge frequency of 6 Hz and transitionband of 1 Hz were found, which facilitates AGI calculation with a standard deviation of 0.06. The study was carried out on 21 healthy subjects and 20 diabetes patients. The linear relationship (r=0.91) between each subject’s age and AGI was found, and a linear model with regression line was constructed. For diabetes patients, the mean AGI value difference from the proposed model yAGI was found to be 0.359. The difference was found between healthy and diabetes patients groups with significance level of P<0.0005

Health Risks to Computer Workers in Various Indoor Facilities

Musculoskeletal disorders (MSDs) are the main cause of occupational diseases in Estonia and Europe. The number of MSDs has increased with the increasing number of computer workers and the increasing workload overall. In the current paper, the survey of 295 workers in Estonian enterprises is carried out to clarify the reasons of occupational stress. The causes of occupational stress are non-ergonomically designed workplace, social and human factors. The main questionnaires used were KIVA and GPSnordic. The conclusion is that KIVA questionnaire alone is too mild to point out the risk factors. The comparison with other questionnaires has to be carried out

Photoplethysmographic signal processing using adaptive sum comb filter for pulse delay measurement

Abstract. Pulse transit time, which correlates with blood pressure, is measured between the electrocardiogram R-wave peak and 50 % raising front level of a photoplethysmographic (PPG) signal. Registered PPG signal bandwidth may be shared by noise and therefore the signal raising front is undetectable. Electrocardiogram reference adaptive sum comb filter was used to extract the harmonic components of the PPG signal and suppress the noises between them. Averaging effect of the filter on the PPG signal was studied and adjustments were made. The influence of the comb filtered PPG signal on the measurement of pulse transit time was analysed. Key words: photoplethysmography, electrocardiography, pulse transit time, adaptive comb filter. 1

Health Risks to Computer Workers in Various Indoor Facilities

Musculoskeletal disorders (MSDs) are the main cause of occupational diseases in Estonia and Europe. The number of MSDs has increased with the increasing number of computer workers and the increasing workload overall. In the current paper, the survey of 295 workers in Estonian enterprises is carried out to clarify the reasons of occupational stress. The causes of occupational stress are non-ergonomically designed workplace, social and human factors. The main questionnaires used were KIVA and GPSnordic. The conclusion is that KIVA questionnaire alone is too mild to point out the risk factors. The comparison with other questionnaires has to be carried out

New Photoplethysmographic Signal Analysis Algorithm for Arterial Stiffness Estimation

The ability to identify premature arterial stiffening is of considerable value in the prevention of cardiovascular diseases. The "ageing index" (AGI), which is calculated from the second derivative photoplethysmographic (SDPPG) waveform, has been used as one method for arterial stiffness estimation and the evaluation of cardiovascular ageing. In this study, the new SDPPG analysis algorithm is proposed with optimal filtering and signal normalization in time. The filter parameters were optimized in order to achieve the minimal standard deviation of AGI, which gives more effective differentiation between the levels of arterial stiffness. As a result, the optimal low-pass filter edge frequency of 6 Hz and transitionband of 1 Hz were found, which facilitates AGI calculation with a standard deviation of 0.06. The study was carried out on 21 healthy subjects and 20 diabetes patients. The linear relationship (r = 0.91) between each subjects age and AGI was found, and a linear model with regression line was constructed. For diabetes patients, the mean AGI value difference from the proposed model y(AGI) was found to be 0.359. The difference was found between healthy and diabetes patients groups with significance level of P andlt; 0.0005.Funding Agencies|Estonian Science Foundation|7506|Estonian Targeted Financing Project|SF0140027s07|European Union through the European Regional Development Fund||</p

QT Interval Variability Index and QT Interval Duration in Different Sleep Stages: Analysis of Polysomnographic Recordings in Nonapneic Male Patients

The aim of the study was to determine whether different sleep stages, especially REM sleep, affect QT interval duration and variability in male patients without obstructive sleep apnea (OSA). Polysomnographic recordings of 30 patients were analyzed. Beat-to-beat QT interval variability was calculated using QTV index (QTVI) formula. For QTc interval calculation, in addition to Bazett’s formula, linear and parabolic heart rate correction formulas with two separate α values were used. QTVI and QTc values were calculated as means of 2 awake, 3 NREM, and 3 REM sleep episodes; the duration of each episode was 300 sec. Mean QTVI values were not statistically different between sleep stages. Therefore, elevated QTVI values found in patients with OSA cannot be interpreted as physiological sympathetic impact during REM sleep and should be considered as a risk factor for potentially life-threatening ventricular arrhythmias. The absence of difference of the mean QTc interval values between NREM and REM stages seems to confirm our conclusion that sympathetic surges during REM stage do not induce repolarization variability. In patients without notable structural and electrical remodeling of myocardium, physiological elevation in sympathetic activity during REM sleep remains subthreshold concerning clinically significant increase of myocardial electrical instability