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Physiological Measurement

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https://www.readbyqxmd.com/read/28212113/age-and-gender-dependency-of-physiological-networks-in-sleep
#1
Dagmar Krefting, Christoph Jansen, Thomas Penzel, Fang Han, Jan Kantelhardt
Recently, time delay stability analysis of biosignals has been successfully applied as a multivariate time series analysis method to assess the human physiological network in young adults. The degree of connectivity between different network nodes is described by the so-called link strength. Based on polysomnographic recordings (PSGs), it could be shown that the network changes with the sleep stage. Here, we apply the method to a large set of healthy controls spanning six decades of age. As it is well known, that the overall sleep architecture is dependent both on age and on gender, we particularly address the question, if these changes are also found in the network dynamics...
February 17, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28211794/test-retest-reliability-of-muscle-fiber-conduction-velocity-and-fractal-dimension-of-surface-emg-during-isometric-contractions
#2
Matteo Beretta-Piccoli, Giuseppe D'Antona, Cristian Zampella, Marco Barbero, Ron Clijsen, Corrado Cescon
The aim of this study was to determine the test-retest reliability of muscle fiber conduction velocity (CV) and fractal dimension (FD) obtained from multichannel surface electromyographic (sEMG) recordings. Forty healthy recreationally active subjects (20 men and 20 women) performed two elbow flexions on two trials with a 1-week interval. The first was a 20% maximal voluntary contraction (MVC) of 120 s, and the second at 60% MVC held until exhaustion. sEMG signals were detected from the biceps brachii, using bi-dimensional arrays...
February 17, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28199219/clinical-applications-of-near-infrared-diffuse-correlation-spectroscopy-and-tomography-for-tissue-blood-flow-monitoring-and-imaging
#3
Yu Shang, Ting Li, Guoqiang Yu
Near-infrared (NIR) light enables the deep tissue investigation of microvascular hemodynamics. Blood flow is one such available observable promoting a wealth of physiological insight both individually and in combination with other metrics. Diffuse correlation spectroscopy (DCS) and, to a lesser extent, diffuse correlation tomography (DCT), have received interest over the past two decades as noninvasive methods for tissue blood flow measurement and imaging. DCS employs coherent point-illumination NIR light to penetrate deep tissues and commonly uses avalanche photodiodes to detect temporal speckle fluctuations of the diffuse light in a single speckle area of tissue surface, which are sensitive to the motions of red blood cells in the microvasculature of the detected tissue volume...
February 15, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28199218/surface-emg-and-muscle-fatigue-multi-channel-approaches-to-the-study-of-myoelectric-manifestations-of-muscle-fatigue
#4
Marco Gazzoni, Alberto Botter, Taian Vieira
On a broad view, fatigue is used to indicate a somewhat degree of weariness. On the muscular level, fatigue posits the reduced capacity of muscle fibres to produce force, even in the presence of motor neuron excitation via either spinal mechanisms or electric pulses applied externally. Prior to decreased force, when sustaining physically demanding tasks, alterations in the muscle electrical properties take place. These alterations, termed myoelectric manifestation of fatigue, can be assessed non-invasively with a pair of surface electrodes positioned appropriately on the target muscle; traditional approach...
February 15, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28186496/ecg-derived-respiration-comparison-of-time-domain-approaches-and-application-to-altered-breathing-patterns-of-patients-with-schizophrenia
#5
Marcus Schmidt, Andy Schumann, Jonas Mueller, Karl-Juergen Baer, Georg Rose
In life-threatening diseases and in several clinical interventions, monitoring of vital parameters is essential to guarantee the safety of patients. Besides monitoring the electrocardiogram (ECG), it is helpful to assess respiratory activity. If the respiration signal itself is not recorded, it can be extracted from the ECG (i.e. ECG derived respiration, EDR). In the present paper, we compared six EDR approaches, namely RS-decline quantified by central moments, respiratory sinus arrhythmia (RSA), R-wave amplitude, QRS area, RS-distance and maximum RS-slope...
February 10, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28186494/oscillatory-pattern-of-acral-skin-blood-flow-within-thermoneutral-zone-in-healthy-humans
#6
Maja Elstad, Ilias Zilakos, Tone Bergersen
OBJECTIVE: The acral skin contains arteriovenous anastomoses, which probably is the main part of skin microcirculation for blood flow adjustments and thermoregulation in the thermoneutral zone. The objective was to investigate if an increase in sympathetic activation during cooling influences the oscillatory pattern of acral skin blood flow. APPROACH: We had measurements of bilateral acral skin blood flow (n=12) during lowering of ambient temperature from 32°C to 18°C...
February 10, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28186000/monitoring-fetal-maturation-objectives-techniques-and-indices-of-autonomic-function
#7
Dirk Hoyer, Jan Zebrowski, Dirk Cysarz, Hernani Goncalves, Adelina Pytlik, Celia Amorim-Costa, Joao Bernardes, Diogo Ayres-de-Campos, Otto Witte, Ekkehard Schleussner, Lisa Stroux, Christopher Redman, Antoniya Georgieva, Stephen Payne, Gari Clifford, Maria Signorini, Giovanni Magenes, Fernando Andreotti, Hagen Malberg, Sebastian Zaunseder, Igor Lakhno, Uwe Schneider
Monitoring the fetal behavior does not only have implications for acute care but also for identifying developmental disturbances that burden the entire later life. The concept, of "fetal programming", also known as "developmental origins of adult disease hypothesis", e.g. applies for cardiovascular, metabolic, hyperkinetic, cognitive disorders. Since the autonomic nervous system is involved in all of those systems, cardiac autonomic control may provide relevant functional diagnostic and prognostic information...
February 10, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28177299/development-of-an-improved-wearable-device-for-core-body-temperature-monitoring-based-on-the-dual-heat-flux-principle
#8
Jingjie Feng, Congcong Zhou, Cheng He, Yuan Li, Xuesong Ye
In this paper, a miniaturized wearable core body temperature (CBT) monitoring system based on the dual heat flux (DHF) principle was developed. By interspersing calcium carbonate powder in PolyDimethylsiloxane (PDMS), a reformative heat transfer medium was produced to reduce the thermal equilibrium time. Besides, a least mean square (LMS) algorithm based active noise cancellation (ANC) method was adopted to diminish the impact of ambient temperature fluctuations. Theoretical analyses, finite element simulation, experiments on a hot plate and human volunteers were performed...
February 8, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28176677/predicting-burst-pressure-of-radiofrequency-induced-colorectal-anastomosis-by-bio-impedance-measurement
#9
Lingxi Zhao, Yu Zhou, Chengli Song, Zhigang Wang, Alfred Cuschieri
The present study investigates the relationship between bio-impedance and burst pressure of colorectal anastomosis created by radiofrequency (RF)-induced tissue fusion. Colorectal anastomosis were created with ex vivo porcine colorectal segments, during which 5 levels of compression pressure were applied by a custom-made bipolar prototype, with 5 replicate experiments at each compression pressure. Instant anastomotic tensile strength was assessed by burst pressure. Bio-impedance of fused tissue was measured by Impedance Analyzer across frequency that 100 Hz to 3 MHz...
February 8, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28176674/a-model-for-generating-synthetic-arterial-blood-pressure
#10
A Mahdi, G D Clifford, S J Payne
A new model capable of simulating many important aspects of human arterial blood pressure (ABP) is proposed. Both data-driven approach and physiological principles have been applied to describe the time series of diastolic, systolic, dicrotic notch and dicrotic peak pressure points. Major static and dynamic features of the model can be prescribed by the user, including heart rate, mean systolic and diastolic pressure, and the corresponding physiological control quantities, such as baroreflex sensitivity coefficient and Windkessel time constant...
February 8, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28169836/photoplethysmography-sampling-frequency-pilot-assessment-of-how-low-can-we-go-to-analyze-pulse-rate-variability-with-reliability
#11
Ahyoung Choi, Hangsik Shin
Pulse rate variability (PRV) analysis appears as the first alternative to heart rate variability analysis for wearable devices; however, there is a constraint on computational load and energy consumption for the limited system resources available to the devices. Considering that adjustment of the sampling frequency is one of the strategies for reducing computational load and power consumption, this study aimed to investigate the influence of sampling frequency (fs) on PRV analysis and to find the minimum sampling frequency while maintaining reliability...
February 7, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28169835/theoretical-modeling-of-a-portable-x-ray-tube-based-kxrf-system-to-measure-lead-in-bone
#12
Aaron James Specht, Marc Weisskopf, Linda Nie
K-shell x-ray fluorescence (KXRF) techniques have been used to identify health effects resulting from exposure to metals for decades, but the equipment is bulky and requires significant maintenance and licensing procedures. A portable x-ray fluorescence (XRF) device was developed to overcome these disadvantages, but introduced a measurement dependency on soft tissue thickness. With recent advances to detector technology, an XRF device utilizing the advantages of both systems should be feasible. In this study, we used Monte Carlo simulations to test the feasibility of an XRF device with a high-energy x-ray tube and detector operable at room temperature...
February 7, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28151434/detection-of-atrial-fibrillation-episodes-using-a-wristband-device
#13
Valentina D A Corino, Rita Laureanti, Lorenzo Ferranti, Giorgio Scarpini, Federico Lombardi, Luca Mainardi
Undiagnosed atrial fibrillation (AF) patients are at high risk of cardioembolic stroke or other complications. The aim of this study was to analyze the blood volume pulse (BVP) signals obtained from a wristband device and develop an algorithm for discriminating AF from normal sinus rhythm (NSR) or from other arrhythmias (ARR). Thirty patients with AF, 9 with ARR and 31 in NSR were included in the study. The recordings were obtained at rest from Empatica E4 wristband device and lasted 10 minutes. The analysis, on a two-minute segment, included spectral, variability and irregularity analysis performed on the inter-diastolic interval series, and similarity analysis performed on the BVP signal...
February 2, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28151433/quantifying-cardio-respiratory-phase-synchronisation-a-comparison-of-five-methods-using-ecgs-of-post-infarction-patients
#14
Anja Kuhnhold, Aicko Schumann, Ronny Bartsch, Romy Ubrich, Petra Barthel, Georg Schmidt, Jan W Kantelhardt
Phase synchronization between two weakly coupled oscillators occurs in many natural systems. Since it is difficult to unambiguously detect such synchronization in experimental data, several methods have been proposed for this purpose. Here, we systematically compare and optimize five popular approaches: the automated synchrogram method, the reduced synchrogram method, two variants of a gradient method, and the Fourier mode method. Studying 24h data records from 1455 post-infarction patients, the same data with artificial inaccuracies, and corresponding surrogate data generated by Fourier phase randomization, we identify characteristic differences as well as strengths and weaknesses of each method in detecting episodes of n:1 and n:2 cardio-respiratory phase synchronization...
February 2, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28151429/the-influence-of-adipose-tissue-on-spatially-resolved-near-infrared-spectroscopy-derived-skeletal-muscle-oxygenation-the-extent-of-the-problem
#15
Victor M Niemeijer, Jasper Jansen, Thomas van Dijk, Ruud Spee, Eduard Meijer, Hareld Kemps, Pieter Wijn
OBJECTIVE: Near-infrared spectroscopy (NIRS) measurements of tissue oxygen saturation (StO2) are useful for the assessment of skeletal muscle perfusion and function during exercise, however, they are influenced by overlying skin and adipose tissue. This study explored the extent and nature of the influence of adipose tissue thickness (ATT) on StO2. APPROACH: NIR spatially resolved spectroscopy (SRS) derived oxygenation was measured on vastus lateralis in 56 patients with chronic heart failure (CHF) and 20 healthy control (HC) subjects during rest and moderate intensity exercise with simultaneous assessment of oxygen uptake kinetics (tauVO2onset)...
February 2, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28140353/basic-cardiovascular-variability-signals-mutual-directed-interactions-explored-in-the-information-domain
#16
Michal Javorka, Jana Krohova, Barbora Czippelova, Zuzana Turianikova, Zuzana Lazarova, Kamil Javorka, Luca Faes
The study of short-term cardiovascular interactions is classically performed through the bivariate analysis of the interactions between the beat-to-beat variability of heart period (RR interval from the ECG) and systolic blood pressure (SBP). Recent progress in the development of multivariate time series analysis methods is making it possible to explore how directed interactions between two signals change in the context of networks including other coupled signals. Exploiting these advances, the present study aims at assessing directional cardiovascular interactions among the basic variability signals of RR, SBP and diastolic blood pressure (DBP), using an approach which allows direct comparison between bivariate and multivariate coupling measures...
January 31, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28140349/reliability-of-3d-upper-limb-motion-analysis-in-children-with-obstetric-brachial-plexus-palsy
#17
Judy Mahon, Ailish Malone, Damien Kiernan, Dara Meldrum
: Kinematics, measured by 3D upper limb motion analysis (3D-ULMA), can potentially increase understanding of movement patterns by quantifying individual joint contributions. Reliability in children with obstetric brachial plexus palsy (OBPP) has not been established. OBJECTIVE: This study aimed to determine between session reliability and measurement errors of 3D-ULMA using the acromion method (AM) in children with OBPP. APPROACH: Ten participants (mean 10 years, range 7-15 years, Narakas classification I-III) completed 3D-ULMA on two occasions, mean interval of 8...
January 31, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28140342/fractal-analysis-of-heart-rate-variability-reveals-alterations-of-the-integrative-autonomic-control-of-circulation-in-paraplegic-individuals
#18
Paolo Castiglioni, Giampiero Merati
The autonomic nervous system plays a major role in the integrative control of circulation, possibly contributing to the ���complex��� dynamics responsible for fractal components in heart rate variability. Aim of this study is to evaluate whether an altered autonomic integrative control is identified by fractal analysis of heart rate variability. We enrolled 14 spinal cord injured individuals with complete lesion between the 5th and 11th thoracic vertebra (SCIH), 14 with complete lesion between 12th thoracic and 5th lumbar vertebra (SCIL), and 34 able-bodied controls (AB)...
January 31, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28140341/estimating-the-minimum-stimulation-frequency-necessary-to-evoke-tetanic-progression-based-on-muscle-twitch-parameters
#19
Shogo Watanabe, Shinichi Fukuhara, Takeshi Fujinaga, Hisao Oka
The summation of the muscle force caused by an increase in the firing rate is named a tetanic contraction (tetanus), and the minimum stimulation frequency necessary to evoke an unfused/fused tetanus is related to the contraction time (CT) and relaxation time (RT) of the twitch. In particular, the fusion index (FI) is a very useful indicator, and it is used to evaluate the change in the muscle fiber component ratio. However, the measurement of the FI is invasive, because most patients experience pain during the electrical stimulation for tetanus...
January 31, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28140332/robust-electroencephalogram-phase-estimation-with-applications-in-brain-computer-interface-systems
#20
Esmaeil Seraj, Reza Sameni
OBJECTIVE: In this study, a robust method is developed for frequency-specific electroencephalogram (EEG) phase extraction using the analytic representation of the EEG. Based on recent theoretical findings in this area, it is shown that some of the phase variations-previously associated to the brain response-are systematic side-effects of the methods used for EEG phase calculation, especially during low analytical amplitude segments of the EEG. APPROACH: With this insight, the proposed method generates randomized ensembles of the EEG phase using minor perturbations in the zero-pole loci of narrow-band filters, followed by phase estimation using the signal's analytical form and ensemble averaging over the randomized ensembles to obtain a robust EEG phase and frequency...
January 31, 2017: Physiological Measurement
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