75 research outputs found
Development of pulse wave monitoring system, applying virtual NI instruments.
No full textStudy proposition. Nowadays, when electronics and medical instrumentation gets more increasingly important in diagnostic field of human physiological indexes measurements, there is an increasing demand of cheap and portable instruments for everyday physiological state monitoring. One of the methods that could be implemented for that task is pulse wave measurement. Pulse wave is a very useful hemodynamic indicator usually acquired through biological tissue impedance measurement. This method is useful in many other fields of biomedical diagnostics because of the advantages it provides: an easy and non-invasive procedure, low cost and etc. Major percentage of bioimpedance measuring devices is intended to be used in estimating body composition, body fluids or fat free mass – these are bioelectrical impedance analysis (BIA) and bioimpedance spectroscopy techniques. Impedance measurement can also be useful in measurement and analysis of hemodynamic parameters with so called impedance cardiography method. One disadvantage of these methods is quite complex equipment, which is used. Study purpose. The aim was to miniaturise the known schemes of impedance measurement devices, by changing analogue equipment with virtual instrument solutions, developed by National Instruments in developing a system which could be utilised in human pulse wave measurements. Study results. In this study literature analysis was performed to find about impedance measurement systems and their methods. This knowledge was used in development of bioelectrical impedance measurement system, applying the use of virtual instruments solutions, provided by National Instruments. The results showed that system is capable of measuring human pulse wave and should provide appropriate accuracy
High frequency filtering of 24-hour heart rate data
No full textHeart rate (HR) and its variability (HRV) analysis based on spectral methods have been widely applied for assessment of autonomic nervous system activities. However, an observation of existing frequency dynamic in particular spectral bands of HRV, especially when analysis is done in short time RR interval series, is problematic using these methods. We used self-developed digital filters to solve this problem. The high-frequency (HF; 0.15-0.4 Hz) band of RR intervals is filtered with 3 finite (FIR) and 4 infinite impulse response (IIR) filters from original 24-hour HR record. We showed that the use of various filters for identification of respiration influence on HR. An analysis using FIR filters gives more accurate results, but requires more calculation resources. No differences between results obtained using filtering and spectral analysis were observed. The use of FIR and IIR filters are simple and effective for processing of both, 24-hour data and short-time series of RR intervals
High frequency filtering of 24-hour heart rate data /
No full textHeart rate (HR) and its variability (HRV) analysis based on spectral methods have been widely applied for assessment of autonomic nervous system activities. However, an observation of existing frequency dynamic in particular spectral bands of HRV, especially when analysis is done in short time RR interval series, is problematic using these methods. We used self-developed digital filters to solve this problem. The high-frequency (HF; 0.15-0.4 Hz) band of RR intervals is filtered with 3 finite (FIR) and 4 infinite impulse response (IIR) filters from original 24-hour HR record. We showed that the use of various filters for identification of respiration influence on HR. An analysis using FIR filters gives more accurate results, but requires more calculation resources. No differences between results obtained using filtering and spectral analysis were observed. The use of FIR and IIR filters are simple and effective for processing of both, 24-hour data and short-time series of RR intervals
A novel adaptive noise elimination algorithm in long RR interval sequences for heart rate variability analysis /
No full textAs heart rate variability (HRV) studies become more and more prevalent in clinical practice, one of the most common and significant causes of errors is associated with distorted RR interval (RRI) data acquisition. The nature of such artifacts can be both mechanical as well as software based. Various currently used noise elimination in RRI sequences methods use filtering algorithms that eliminate artifacts without taking into account the fact that the whole RRI sequence time cannot be shortened or lengthened. Keeping that in mind, we aimed to develop an artifacts elimination algorithm suited to long-term (hours or days) sequences that does not affect the overall structure of the RRI sequence and does not alter the duration of data registration. An original adaptive smart time series step-by-step analysis and statistical verification methods were used. The adaptive algorithm was designed to maximize the reconstruction of the heart-rate structure and is suitable for use, especially in polygraphy. The authors submit the scheme and program for use
On the P-wave model of a single electrocardiogram lead
No full textWe describe a parametric model for the P-wave of a single electrocardiogram (ECG) lead trajectory. Though previously met in the bioengineering literature, the model was not treated in a complete parametric fashion. The paper fills the gap by making use of both frequentist and Bayesian approaches. Supporting real data example is provided. Further potential applications are also discussed
Assessment of Dynamic Spectrum Allocation in Realistic Mobile Networks
No full textSince the advent of radio communications, radio spectrum has been increasingly getting crowded with different kinds of applications. Different radio communications systems have been developed for various purposes and multiple actors became interested in using these systems at the same time and space. Such situation inevitably led to the point when practically entire usable radio spectrum became occupied by different actors. To alleviate this problem, Dynamic Spectrum (Re)Allocation (DSA) has been proposed, which is a branch of frequency spectrum management that aims to improve spectrum usage efficiency and end-user experience by introducing more flexibility to spectrum usage. This thesis aims to provide additional insight into DSA applicability and effectiveness in a typical realistic cellular network, in intra-operator scenario, taking into account 2G and 4G radio technologies, with the aim of improving 4G performance without adverse impact to 2G. We use realistic dynamic system level simulations to assess DSA performance in the selected cellular network areas that can be classified as urban, suburban and rural. Our simulation results show that DSA is capable of improving 4G throughput without adverse impact to 2G performance in all simulated areas. Among the simulated areas, urban area benefits from DSA most, as significant throughput gains for 4G are achieved without adverse impact to 2G performance, while simulations show that spectrum refarming is clearly not an option for this type of area. However, throughput gains for 4G in urban area are limited during the busy-hours. Suburban and rural areas indicate benefits from DSA too, however the difference between DSA and spectrum refarming in these areas is diminishing. Hence, with reasonable half-rate timeslot tolerance for 2G voice calls, spectrum refarming could be an option in the simulated suburban and rural areas.Electrical EngineeringNetwork Architectures and ServicesElectrical Engineering, Mathematics and Computer Scienc
Specific fatigue-related items in self-rating depression scales do not bias an association between depression and fatigue in patients with coronary artery disease
No full textLand forces soldier’s systems development (needs and opportunities).
No full textNowadays. the topic of the thesis is relevant, because it concerns the fast developing and one of the most important projects in Lithuanian armed forces called the „Modern Soldier“. The focus of the project is towards the individual equipment and weaponry. Also, in this thesis, the author will concentrate on the individual equipment of Lithuanian armed forces soldier. Lithuanian armed forces soldier equipment was not analysed by Lithuanian authors. Due to that, it is relevant to assess the situation and the perspectives of the new Lithuanian soldier’s equipment in the context of other foreign countries. Methodology – author has chosen the empiric qualitative research, because it helps to understand the problem of the thesis and it is the most comprehensive. In addition, in the theoretical part of the thesis, a comparison between the different countries and their soldiers’ equipment was made. The evaluation of the results showed that the worst logistic situation is in the Lithuanian Military Academy and Lithuanian Volunteer Forces. The suggestion would be that the elements of the equipment should not be bought separately, but rather together as a whole. Due to that, it would allow to avoid the problem of incompatibility. All systems and elements should be modern and updated. Hypothesis: Lithuanian armed forces soldier’s equipment fits the requirements of other foreign countries through complex elements and used technologies
Daily heart rate variability indices in subjects with and without metabolic syndrome before and after the elimination of the influence of day‐time physical activity /
No full textBackground and Objectives: The available research shows conflicting data on the heart rate variability (HRV) in metabolic syndrome (MetS) subjects. The discrepancy suggests a methodical shortcoming: due to the influence of physical activity, the standard measuring of HRV at rest is not comparable with HRV assessment based on 24h Holter monitoring, which is preferred because of its comprehensiveness. To obtain a more reliable measure and to clarify to what extent HRV is altered in MetS, we assessed a 24h HRV before and after the elimination of the influence of physical activity. Materials and Methods: We investigated 69 metabolic syndrome (MetS) and 37 control subjects, aged 50–55. In all subjects, 24h monitoring of electrocardiogram, blood pressure, and actigraphy profiles were conducted. To eliminate the influence of day-time physical activity on RR intervals (RRI), a linear polynomial autoregressive model with exogenous terms (ARX) was used. Standard spectral RRI analysis was performed. Results: Subjects with MetS had blunted HRV; the diurnal SDNN index was reliably lower in the MetS group than in control subjects. The elimination of the influence of physical activity did not reveal a significant HRV change in long-term indices (SDNN, SDANN, and SD2), whilst adjacent RRI values (RMSSD, pNN50, and SD1) and SDNN index significantly increased (p < 0.001). An increase in the latter indices highlighted the HRV difference between the MetS and control groups; a significant (p < 0.001) decrease of all short-term HRV variables was found in the MetS group (p < 0.01), and low-frequency spectral components were less pronounced in the MetS group. Conclusion: The application of a polynomial autoregressive model in 24h HRV assessment allowed for the exclusion of the influence of physical activity and revealed that MetS is associated with blunted HRV, which reflects mitigated parasympathetic tone
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