387 research outputs found

    Die Wechselwirkung der Tonsprache in den einzelnen Gattungen bei Karol Mikuli

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    Das kompositorische Schaffen Karol Mikulis fällt in die Mitte und die 2. Hälfte des 19. Jahrhunderts. Der aus Moldawien stammende Komponist erhielt seine musikalische Ausbildung in Paris bei Chopin. Dies prägte sein gesamtes Werk. Mikuli zählt zu den ersten Herausgebern von Chopins Klavierwerken. Diese Tätigkeit öffnete ihm einen tiefen Einblick in die Technik und Musiksprache jenes führenden Künstlers seiner Epoche

    Spatial heterogeneity of cutaneous blood flow respiratory-related oscillations quantified via laser speckle contrast imaging

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    LSCI technique provides experimental data which can be considered in the context of spatial blood flow coherency. Analysis of vascular tone oscillations gives additional information to ensure a better understanding of the mechanisms affecting microvascular physiology. The oscillations with different frequencies are due to different physiological mechanisms. The reasons for the generation of peripheral blood flow oscillations in the 0.14–0.6 Hz frequency band are as follows: cardio-respiratory interactions, pressure variations in the venous part of the circulatory system, and the effect of the sympathetic nervous system on the vascular tone. Earlier, we described the spatial heterogeneity of around 0.3 Hz oscillations and this motivated us to continue the research to find the conditions for the occurrence of spatial phase synchronization. For this purpose, a number of physiological tests (controlled respiration, breath holder, and venous occlusion tests) which influence the blood flow oscillations of 0.14–0.6 Hz were considered, an appropriate measurement system and the required data processing algorithms were developed. At spontaneous respiration, the oscillations with frequencies around 0.3 Hz were stochastic, whereas all the performed tests induced an increase in spatial coherence. The protocols and methods proposed here can help to clarify whether the heterogeneity of respiratory-related blood flow oscillations exists on the skin surface

    Diagnosis of Skin Vascular Complications Revealed by Time-Frequency Analysis and Laser Doppler Spectrum Decomposition

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    Nowadays, photonics-based techniques are used extensively in various applications, including functional clinical diagnosis, progress monitoring in treatment, and provision of metrological control. In fact, in the frame of practical implementation of optical methods, such as laser Doppler flowmetry (LDF), the qualitative interpretation and quantitative assessment of the detected signal remains vital and urgently required. In the conventional LDF approach, the key measured parameters, index of microcirculation and perfusion rate, are proportional to an averaged concentration of red blood cells (RBC) and their average velocity within a diagnostic volume. These quantities compose mixed signals from different vascular beds with a range of blood flow velocities and are typically expressed in relative units. In the current paper we introduce a new signal processing approach for the decomposition of LDF power spectra in terms of ranging blood flow distribution by frequency series. The developed approach was validated in standard occlusion tests conducted on healthy volunteers, and applied to investigate the influence of local pressure rendered by a probe on the surface of the skin. Finally, in limited clinical trials, we demonstrate that the approach can significantly improve the diagnostic accuracy of detection of microvascular changes in the skin of the feet in patients with Diabetes Mellitus type 2, as well as age-specific changes. The results obtained show that the developed approach of LDF signal decomposition provides essential new information about blood flow and blood microcirculation and has great potential in the diagnosis of vascular complications associated with various diseases

    Comparison of Spider-Robot Information Models

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    The paper deduces a mathematical model of a spider-robot with six three-link limbs. Many limbs with a multi-link structure greatly complicate the process of synthesizing a model, since in total the robot has twenty-four degrees of freedom, i.e., three coordinates of the center of mass of the body in space, three angles of rotation of the body relative to its center of mass and three degrees of freedom for each limb, to describe the position of the links. The derived mathematical model is based on the Lagrange equations with a further transformation of the equations to the Cauchy normal form in a matrix form. To test the resulting model in a SimInTech environment, an information model is synthesized and two simple experiments ar carried out to simulate the behavior of real spiders: moving forward in a straight line and turning in place at a given angle. The experimental results demonstrate that the synthesized information model can well cope with the tasks and the mathematical model underlying it can be used for further research

    Wavelet Analysis of the Temporal Dynamics of the Laser Speckle Contrast in Human Skin

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    Objective: Spectral analysis of laser Doppler flowmetry (LDF) signals has been widely used in studies of physiological vascular function regulation. An alternative to LDF is the laser speckle contrast imaging method (LSCI), which is based on the same physical principle. In contrast to LDF, LSCI provides non-scanning full-field imaging of a relatively wide skin area and offers high spatial and temporal resolutions, which allows visualization of microvascular structure. This circumstance, together with a large number of works which had shown the effectiveness of temporal LSCI analysis, gave impetus to experimental studies of the relation between LDF and LSCI used to monitor the temporal dynamics of blood flow. Methods: Continuous wavelet transform was applied to construct a time-frequency representation of a signal. Results: Analysis of 10 minute LDF and LSCI output signals recorded simultaneously revealed rather high correlation between oscillating components. It was demonstrated for the first time that the spectral energy of oscillations in the 0.01-2 Hz frequency range of temporal LSCI recordings carries the same information as the conventional LDF recordings and hence it reflects the same physiological vascular tone regulation mechanisms. Conclusion: The approach proposed can be used to investigate speckle pattern dynamics by LSCI in both normal and pathological conditions. Significance: The results of research on the influence of spatial binning and averaging on the spectral characteristics of perfusion monitored by LSCI are of considerable interest for the development of LSCI systems optimized to evaluate temporal dynamics

    Wearable laser Doppler sensors for evaluating the nutritive and shunt blood flow

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    This study is devoted to the trials of wearable diagnostic system that implements the laser Doppler flowmetry technique to analyse the blood microcirculation. We do preliminary test with involvement of limited group of healthy volunteers of different age and in patients with type 2 diabetes. During the series of measurements, the microcirculation parameters was measured for 10 minutes in the palmar surfaces of the big toes and in the inner sides of the upper thirds of the shins. A statistically significant differences was found in bypass index, nutritive and shunt blood ow in shins between older group of volunteers and patients' group as well as in shunt blood flow in fingers between younger and older groups of volunteers

    Peculiarities of local blood microcirculation in patients with psoriasis

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    Local hemodynamic parameters were studied by means of laser Doppler flowmetry in 15 patients with psoriasis in the stationary stage, who have plaques on the inner surface of the forearm. LDF signals recorded at the site of psoriatic lesions of the tissue as well as in the intact tissue at a distance of 1-2 cm from the affected area were analysed. LDF signals were postprocessed by continuous wavelet transform using the Morlet wavelet

    Laser Doppler flowmetry in blood and lymph monitoring, technical aspects and analysis

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    The aim of this work was to study the possibilities of the laser Doppler flowmetry method for the joint study of microhaemo- and lymph circulation of human skin. Conducting a series of experimental studies allowed to trace the relationship of recorded signals of microcirculation of blood flow and lymph flow, as well as to study their oscillation nature by using wavelet analysis

    Laser speckle contrast imaging of abdominal organs in mouse model

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    Diagnosis and treatment of acute destructive pancreatitis is one of the most urgent problems of abdominal surgery. To obtain additional diagnostic information about the microcirculation state and metabolic processes, various imaging techniques are widely used during surgical interventions. One of the most perspective techniques for in vivo microcirculation assessment is laser speckle-contrast imaging (LSCI), allowing for evaluation of blood perfusion. The experimental results showed the possibility to evaluate the blood perfusion of the mouse pancreas in the simulation of ischemia using the LSCI method

    Optical fine-needle biopsy approach for intraoperative multimodal diagnostics in minimally invasive abdominal surgery

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    The paper describes the methodology and technical implementation of a multimodal approach for optical diagnostics in hepatopancreatobiliary organs focal and diffuse neoplasms. Fine needle aspiration biopsy technique and following cytological examination show its effectiveness and safety but its performing takes several days. However, the problem of real-time analysis of pathological changes in tissues remains relevant. The solution suggested is implementing of optical biopsy methods (namely fluorescence spectroscopy and diffuse reflectance spectroscopy) in the form of fiber-optic probe compatible with standard biopsy fine needles. The special device was designed for this purpose to conduct optical measurements and compare the results with ones obtained by conventional biopsy. The proposed methodology seems promising for developing new diagnostic criteria for clinical practice
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