Phase Angle Relationship Research Articles

The relationship of bioelectrical impedance phase angle and nutrition risk in healthy Thai older persons

The relationship of bioelectrical impedance phase angle and nutrition risk in healthy Thai older persons

Impact of a Single Episode of Different Intensity of White Light Pulse at Night on Masking Response in the Diurnal Mammal, Funambulus pennantii

Objective: Light affects mammalian circadian rhythms through entrainment and masking. Photic masking increases locomotor activity in diurnal species (positive masking) while reducing activity in nocturnal species (negative masking). Fewer studies have investigated masking in diurnal rodents. We investigated the masking response in a diurnal rodent, <i>Funambulus pennantii</i> when subjected to white light pulses of different intensities at night between zeitgeber time (ZT) 12 and ZT 15.Methods: Adult male squirrels, <i>F. pennantii</i> (n=10/group, three groups) were placed in individual cages with running wheels under standard 12:12 h light-dark (LD) conditions. Recording of the locomotor activity rhythm was carried out using a ClockLab setup. Following a week of stable entrainment to the LD cycle, the animals of each group were given a sham exposure. After 10 days, animals of group I, II, and III were exposed to 3-h white light pulses of 100 lux, 10 lux, and 1 lux, respectively, between ZT 12 and ZT 15. Following the exposure, the animals were allowed to run undisturbed for 7 days.Results: Compared to the shamexposed group, exposure to 3-h 1 lux, 10 lux, and 100 lux artificial light pulses at night caused positive masking, stimulating wheel running in an intensity-dependent manner. Additionally, nighttime light pulses of 100 lux and 10 lux reduced onset accuracy, reduced the amplitude of the rhythm, and also altered the phase angle relationship to light.Conclusion: The positive masking caused by light exposure at night in diurnal squirrels is intensity-dependent up to at least 100 lux and is associated with a dampening of circadian rhythms.

Relationship of phase angle and skeletal muscle index in patients with liver cirrhosis of different etiologies

Introduction. Sarcopenia is common among patients with liver cirrhosis (LC) and has a significant impact on the quality of life of patients, the nature of the course of the disease and mortality. The phase angle (PhA) is the arctangent of the ratio of reactive and active resistances for a variable frequency current obtained using bioimpedance analysis. Data on the relationship between PhA and sarcopenia are limited, so the analysis of this topic is the important step towards understanding the role of sarcopenia in LC.The objective was to evaluate the relationship between the values of the phase angle and the index of skeletal musculature obtained by CT volumetry in patients with LC.Methods and materials. The study included 15 patients diagnosed with LC. The anthropometric examination was carried out, followed by an assessment of the component composition of the patients’ body using the ABC-01 «Medass» device (STC Medass, Russia). According to the indications, all patients underwent CT of the abdominal cavity without contrast enhancement.Results. Median and interquartile interval PhA (°): 5.3 [4.2–5.7] in men and 5.2 [4.9–6.1] in women, skeletal muscle index (cm2/m2): 51.82 [48.33–53.75] cm2/m2 in men and 44.114 [38.9–49.32] cm2/m2 in women. The correlation analysis revealed a positive correlation of the average strength between the skeletal muscle index (cm2/m2) and PhA (°): r=0.2619, p-value=0.036845.Conclusion. Determination of the components of body composition and their relationship with the course of diseases in patients with LC may have practical application and requires further study.

421 Whole Body Phase Angle and Body Composition and Relationship to Frailty in Kidney Transplant Recipients (KTRs)

421 Whole Body Phase Angle and Body Composition and Relationship to Frailty in Kidney Transplant Recipients (KTRs)

Synergistic changes in river-lake runoff systems in the Yangtze River basin and their driving force differences

Climate change and human activities simultaneously alter river–lake relationships. Determining the dynamics of river–lake runoff systems on multiple time scales and their differences in response to driving forces can provide insights into hydrological processes and water resource management. This study investigates the synergistic evolution of river–lake runoff systems in the middle and lower reaches of the Yangtze River basin (MLYR) using the cross-wavelet transform method. The effects of different driving force changes on river–lake runoff regimes are quantified based on the Budyko hypothesis, and an InVEST model is developed to assess the spatial and temporal patterns of habitat quality. The results indicate that during the variation period, the runoff distributions of the Yangtze River–Dongting Lake and Yangtze River–-Poyang Lake runoff systems are both skewed towards lower values in the flood seasons compared with those in the base period. The storage of lakes mitigates the extent of human disturbance to the mainstream hydrological regime, particularly under extremely low conditions. From 1960 to 2021, five significant resonance periods are indicated in the river–lake runoff system, and the phase–angle relationships indicate a positive phase coupling between the lake and mainstream hydrological regimes, with the lake lagging behind the mainstream; however, this interaction tends to weaken. In the mainstream and Dongting Lake basins, subsurface conditions are the dominant factor contributing to runoff variability, with contributions ranging from 50.9% to 72.6%; in the Poyang Lake basin, precipitation is the dominant factor, with a contribution of 50.6%; and in the Han River basin, changes in the potential evapotranspiration contribute to 50.6% of runoff variability. The proportion of high habitat quality in the MLYR is approximately 52%, the Dongting and Poyang Lake basins indicate a high habitat quality rating. However, frequent human activity is the main reason of conversion from higher habitats to lower ones, which may result in wetland habitat degradation.

Factors of Muscle Quality and Determinants of Muscle Strength: A Systematic Literature Review.

Muscle quality defined as the ratio of muscle strength to muscle mass disregards underlying factors which influence muscle strength. The aim of this review was to investigate the relationship of phase angle (PhA), echo intensity (EI), muscular adipose tissue (MAT), muscle fiber type, fascicle pennation angle (θf), fascicle length (lf), muscle oxidative capacity, insulin sensitivity (IS), neuromuscular activation, and motor unit to muscle strength. PubMed search was performed in 2021. The inclusion criteria were: (i) original research, (ii) human participants, (iii) adults (≥18 years). Exclusion criteria were: (i) no full-text, (ii) non-English or -German language, (iii) pathologies. Forty-one studies were identified. Nine studies found a weak–moderate negative (range r: [−0.26]–[−0.656], p < 0.05) correlation between muscle strength and EI. Four studies found a weak–moderate positive correlation (range r: 0.177–0.696, p < 0.05) between muscle strength and PhA. Two studies found a moderate-strong negative correlation (range r: [−0.446]–[−0.87], p < 0.05) between muscle strength and MAT. Two studies found a weak-strong positive correlation (range r: 0.28–0.907, p < 0.05) between θf and muscle strength. Muscle oxidative capacity was found to be a predictor of muscle strength. This review highlights that the current definition of muscle quality should be expanded upon as to encompass all possible factors of muscle quality.

Relationship of phase angle and peak torque of knee extensors with the performance in six-minute step test in haemodialysis patients

BackgroundChronic kidney disease is a systemic disease affecting not only renal function, but also endocrine, cardiovascular, and skeletal muscle systems, with broad impact on functionality. Therefore, the assessment of body composition, peripheral muscle function, and exercise tolerance is also of great importance in this population. In addition, the development of reliable strategies that use feasible tools in clinical practice is of great importance in the functional diagnosis, clinical management and prescription of physical activity.ObjectiveTo assess the relationship between phase angle and peak torque of knee extensors with the performance in six-minute step test of patients with chronic kidney disease undergoing haemodialysis.MethodsObservational and cross-sectional study at Haemodialysis Centre of Sírio-Libanês Hospital. The evaluations took place 3 days before the haemodialysis sessions. On the first day, patients underwent anthropometric evaluation and biochemical tests (lactate, urea, creatinine, albumin, ferritin and growth factor similar to insulin type 1 [IGF1]). On the second day, performed electrical bioimpedance and exercise tolerance assessed using the six-minute step test. On the last day, the evaluation of knee extensor muscles strength using isokinetic dynamometry was performed.ResultsEighteen subjects were included, with a mean age of 62.3 ± 17.6 years. A positive linear correlation was observed between the phase angle, derived from the electrical bioimpedance, and the performance in six-minute step test in these patients. It was also possible to observe a linear correlation between phase angle and IGF1, handgrip strength, peak torque of knee extensors and quality of life questionnaire. The peak torque of knee extensors also presented a linear correlation with IGF1, the performance in six-minute step test and mal-nutrition and inflammation score.ConclusionPhase angle and peak torque of knee extensors were correlated with the performance in six-minute step test. Therefore, the phase angle seems to be an important marker of reduced peripheral muscle function and exercise tolerance in haemodialysis patients.

A data-driven model for phase angle behaviour of asphalt concrete mixtures based on convolutional neural network

Selection of asphalt concrete (AC) mixtures with proper knowledge of its phase angle characteristics is critical in designing flexible pavements and ensuring the maximum service life of pavements. To achieve this purpose, laborious and expensive laboratory testings are frequently performed, and the results are implied to field. To overcome this problem, models (mathematical or machine learning) are developed to predict the phase angle of AC mixtures. However, the complex and non-linear relationship of phase angle with its independent variables is hard to capture using simple mathematical (or statistical) models. As such, this study proposes a data-driven model based on Convolutional Neural Network (CNN) to capture and predict the phase angle behaviour of AC mixtures. Twenty-three AC mixtures are prepared in laboratory consisting of varying gradations, binder grades, and mix types to perform phase angle testing. The proposed modelling framework, trained using the dataset obtained from laboratory testing, captures 90% of the variance in the test data, which is a significant improvement as compared with other machine learning models as well as linear regression. The proposed model has the capability to capture the non-linearity associated with AC mixtures and can be used by transport agencies and practitioners as a surrogate to tedious laboratory testing.

Comprehensive evaluation of hydrological drought and its relationships with meteorological drought in the Yellow River basin, China

Under the background of global warming, the acceleration of water cycle process will aggravate the risk of hydrological drought in the river basin. The Yellow River basin (YRB) is the most severely affected area by drought in China’s major river basins, so it is particularly important to comprehensively evaluate the hydrological drought and explore its relationships with meteorological drought in the YRB. In this study, the Standardized Streamflow Index (SSI) was adopted as a hydrological drought index, and the evolution characteristics of hydrological drought were comprehensively evaluated in the YRB from 1961 to 2015. The duration and severity of hydrological drought events were identified based on run theory, and the copula functions with the highest goodness of fit (GOF) were used to investigate the drought return period. Finally, the Standardized Precipitation Evapotranspiration index (SPEI) was adopted as a meteorological drought index, and the relationships between hydrological and meteorological drought were revealed by cross wavelet transform method. The results indicated that: (1) drought showed an increasing trend in the YRB from 1961 to 2015, while the worst drought occurred in 1997; (2) the trend characteristic of drought was different in each subzone; (3) the most severe drought lasted for 32 months, with drought severity of 43.29, and drought return period of 23.26 years; (4) Frank-copula was considered to be the best-fitted copula function in the YRB; and (5) the cross wavelet transform illustrated that there was a positive correlation between hydrological and meteorological drought, and the phase angle relationships indicated that meteorological drought occurred earlier than hydrological drought in the YRB.

The Mechanism of Ultra-Low Frequency Oscillations With the Same Mode Shapes

The ultra-low frequency oscillation (ULFO) problem reappears in China recently. Different from the classical low frequency oscillation (LFO), the generators in ULFO have the same mode shapes, namely oscillating in the same pace. To reveal the reason why ULFO generators do not oscillate inversely as classical LFO does, this paper investigates the mechanism of ULFO based on improved Philips-Heffron model of two-machine system. Through this model, the phase angle relationship between different generators is obtained. Based on the bode diagram, it is found that the phase angle difference of the two machines is around zero in ultra-low frequency band however the generator parameters change. On the contrary, the situation is different in classical low frequency band, which reveals the mechanism that generators in ULFO always oscillate in the same pace. Finally, the analysis above is validated through a 2-area 4-machine system and a 6-machine system established in PSASP software.

Elucidation of Phase Angle Values and Relationship between Phase Angle and Motor Performance in Japanese Adolescents

Elucidation of Phase Angle Values and Relationship between Phase Angle and Motor Performance in Japanese Adolescents

On-board data synchronization in wireless structural health monitoring systems based on phase locking

Wireless sensor networks are prone to synchronization discrepancies, due to the lack of intrinsic global clock management from a centralized server. In wireless structural health monitoring (SHM) systems, synchronization discrepancies may lead to erroneous estimations of structural parameters of monitored structures. To avoid errors in the estimations of structural parameters, structural response data sets collected from a structure must be synchronized. Synchronization between structural response data sets can be achieved through offline processing. However, in wireless SHM systems, offline processing requires wireless communication of entire structural response data sets, which has been proven detrimental to the power autonomy of wireless sensor nodes. This paper presents an embedded synchronization algorithm for wireless SHM systems. The embedded synchronization algorithm functions as a module added to embedded algorithms performing peak picking, which is part of operational modal analysis, for ensuring accurate outcomes. The embedded synchronization algorithm enables wireless SHM systems to synchronize structural response data sets on board using the embedded computing capabilities of wireless sensor nodes. The synchronization is achieved by imposing the expected relationship between the phase angles of Fourier spectra of acceleration response data sets at peaks corresponding to vibration modes. Time lags are autonomously estimated by the wireless sensor nodes through collaborative analysis of the phase angle relationship between acceleration response data sets collected by different sensor nodes. The embedded synchronization algorithm is implemented into a prototype wireless SHM system with embedded peak picking algorithms and validated by laboratory tests and by ambient vibration tests on a pedestrian bridge.

Wavenumber–frequency deconvolution of aeroacoustic microphone phased array data of arbitrary coherence

Deconvolution of aeroacoustic data acquired with microphone phased arrays is a computationally challenging task for distributed sources with arbitrary coherence. A new technique for performing such deconvolution is proposed. This technique relies on analysis of the array data in the wavenumber–frequency domain, allowing for fast convolution and reduced storage requirements when compared to traditional coherent deconvolution. A positive semidefinite constraint for the iterative deconvolution procedure is implemented and shows improved behavior in terms of quantifiable convergence metrics when compared to a standalone covariance inequality constraint. A series of simulations validates the method׳s ability to resolve coherence and phase angle relationships between partially coherent sources, as well as determines convergence criteria for deconvolution analysis. Simulations for point sources near the microphone phased array show potential for handling such data in the wavenumber–frequency domain. In particular, a physics-based integration boundary calculation is described, and can successfully isolate sources and track the appropriate integration bounds with and without the presence of flow. Magnitude and phase relationships between multiple sources are successfully extracted. Limitations of the deconvolution technique are determined from the simulations, particularly in the context of a simulated acoustic field in a closed test section wind tunnel with strong boundary layer contamination. A final application to a trailing edge noise experiment conducted in an open-jet wind tunnel matches best estimates of acoustic levels from traditional calculation methods and qualitatively assesses the coherence characteristics of the trailing edge noise source.

High flow nasal heliox improves work of breathing and attenuates lung injury in a newborn porcine lung injury model.

High flow nasal cannula (HFNC) has been shown to improve ventilation and oxygenation and reduce work of breathing in newborns with respiratory distress. Heliox, decreases resistance to airflow, reduces the work of breathing, facilitates the distribution of inspired gas, and has been shown to attenuate lung inflammation during the treatment of acute lung injury. Heliox delivered by HFNC will decrease resistive load, decrease work of breathing, improve ventilation and attenuate lung inflammation during spontaneous breathing following acute lung injury in the newborn pig. Spontaneously breathing neonatal pigs received Nitrox or Heliox by HFNC and studied over 4 hrs following oleic acid injury. Gas exchange, pulmonary mechanics and systemic inflammation were measured serially. Lung inflammation biomarkers were assessed at termination. Heliox breathing animals demonstrated lower work of breathing reflected by lower tracheal pressure, phase angle and phase relationship. Ventilation efficiency index was greater compared to Nitrox. Heliox group showed less lung inflammation reflected by lower tissue interleukin-6 and 8. High flow nasal Heliox decreased respiratory load, reduced resistive work of breathing indices and attenuated lung inflammatory profile while ventilation was supported at less pressure effort in the presence of acute lung injury.

A Novel Method of Ground Fault Phase Selection in Weak-Infeed Side

The sequence current-based fault phase selector and traditional low-voltage fault phase selector have difficulties in being applied to the weak-infeed side. This study proposes a new method of ground fault phase selection for high-voltage/extra-high-voltage transmission-line protection under weak-infeed conditions. The method utilizes the relative phase-angle relationship between negative- and zero-sequence voltages and a relative phase relationship between superimposed positive-sequence voltage and superimposed negative-sequence voltage to identify the fault phase under weak-infeed conditions. Theory analysis and simulation have proven that the proposed method has high immunity against fault resistance as well as impedance phase-angle inequality and overload.

Variations in the rate and direction of re-entrainment to acute simulated jet lag in the diurnal North Indian palm squirrel

We report the presence of variations in the rate and direction of re-entrainment to acute simulated jet lag in wild-caught North Indian palm squirrels (Funambulus pennanti). Adult laboratory and wheel-acclimated (Lafayette, USA) males (N = 30) were entrained to a 12:12 h light/dark (LD) schedule, followed by a 9 h advance of the LD schedule to simulate acute jet lag. The direction and rate of re-entrainment, i.e. the number of orthodromic (advancing) and antidromic (delaying) transients, the acrophases of daily rhythms in each case, duration of activity (α) and phase angle relationship (ψ) were noted using Clocklab (Coulbourn, USA). The squirrels exhibited distinct variations in their response to simulated acute jet lag, re-entraining either slowly (14/30) or rapidly (10/30) by advancing transients, or undergoing antidromic re-entrainment slowly (5/30), and, in only one individual, rapidly. Acrophases re-entrained slower than onsets. α underwent compression during re-entrainment, particularly during fast orthodromic responses. ψ was not significantly different in any of the groups before or after re-entrainment. This phenomenon has scope for further investigation and highlights the need for individual assessment of re-entrainment patterns before taking preventive measures for jet lag.

Multiscale spectral analysis of temporal variability in evapotranspiration over irrigated cropland in an arid region

The temporal patterns of evapotranspiration (ET) and its biophysical and physiological controls (e.g., soil water content, solar radiation, and canopy conductance) occur over a wide range of time-scales ranging from seconds to decades. Thus, there is increasing interest in understanding at which scales the main temporal correlations between ET and its controlling factors occur across different ecosystems. For this study, we used eddy covariance measurements of ET over 2 years at an irrigated maize field in an arid inland region of northwest China. We applied the wavelet transform as a novel technique to examine spectral characteristics of ET and its controlling factors. The ET power spectra displayed a −1 power law in turbulent inertial subrange at <1-h time-scale, and showed substantial power at daily, seasonal and annual time-scales. The cospectra of ET and soil water content (SWC) showed significant temporal correlation at 5-days, which has implications for calculation of ET using the soil water balance method in this region. We found that ET synchronized with the change of net radiation, and led vapor pressure deficit and air temperature for ∼2h at the 1-day time-scale (i.e., positive lags), but the phase relationship between ET and SWC was influenced by irrigation patterns. Canopy conductance influenced ET variability at the 1-day time-scale, but the effect was not consistent across the growing seasons. Our results show the importance of irrigation practices and its influence on the multi-temporal correlations of ET and its controlling factors. Irrigation can sharply change the phase angle relationship of ET and SWC from −10h to 10h. These results are important for understanding water cycle processes, improving water management, and address food security issues across irrigated croplands in arid regions.

Objective measures of sleep and dim light melatonin onset in adolescents and young adults with delayed sleep phase disorder compared to healthy controls

Delayed sleep phase disorder is characterized by a delay in the timing of the major sleep period relative to conventional norms. The sleep period itself has traditionally been described as normal. Nevertheless, it is possible that sleep regulatory mechanism disturbances associated with the disorder may affect sleep duration and/or architecture. Polysomnographic data that may shed light on the issue are scarce. Hence, the aim of this study was to examine polysomnographic measures of sleep in adolescents and young adults with delayed sleep phase disorder, and to compare findings to that of healthy controls. A second aim was to estimate dim light melatonin onset as a marker of circadian rhythm and to investigate the phase angle relationship (time interval) between dim light melatonin onset and the sleep period. Data from 54 adolescents and young adults were analysed, 35 diagnosed with delayed sleep phase disorder and 19 healthy controls. Results show delayed timing of sleep in participants with delayed sleep phase disorder, but once sleep was initiated no group differences in sleep parameters were observed. Dim light melatonin onset was delayed in participants with delayed sleep phase disorder, but no difference in phase angle was observed between the groups. In conclusion, both sleep and dim light melatonin onset were delayed in participants with delayed sleep phase disorder. The sleep period appeared to occur at the same circadian phase in both groups, and once sleep was initiated no differences in sleep parameters were observed.

Fault phase selection scheme of EHV/UHV transmission line protection for high-resistance faults

This study proposes a fault phase selection scheme for EHV/UHV transmission line protection during unbalanced faults. The scheme utilises the relative phase angle relationship between the negative and zero sequence currents and the fault impedance to identify the fault phase, providing particularly satisfactory tolerance towards high-fault resistance during normal operating situations and power swings. Real time digital simulator (RTDS) simulations demonstrate the outstanding performance of the proposed scheme in varying pre-fault system and fault conditions.

CFD analysis of high frequency miniature pulse tube refrigerators for space applications with thermal non-equilibrium model

High frequency, miniature, pulse tube cryocoolers are extensively used in space applications because of their simplicity. Parametric studies of inertance type pulse tube cooler are performed with different length-to-diameter ratios of the pulse tube with the help of the FLUENT (R) package. The local thermal non-equilibrium of the gas and the matrix is taken into account for the modeling of porous zones, in addition to the wall thickness of the components. Dynamic characteristics and the actual mechanism of energy transfer in pulse are examined with the help of the pulse tube wall time constant. The heat interaction between pulse tube wall and the oscillating gas, leading to surface heat pumping, is quantified. The axial heat conduction is found to reduce the performance of the pulse tube refrigerator. The thermal non-equilibrium predicts a higher cold heat exchanger temperature compared to thermal equilibrium. The pressure drop through the porous medium has a strong non-linear effect due to the dominating influence of Forchheimer term over that of the linear Darcy term at high operating frequencies. The phase angle relationships among the pressure, temperature and the mass flow rate in the porous zones are also important in determining the performance of pulse tuberefrigerator.