Cut-off Angle Research Articles

Association between phase angle and sarcopenia in patients with connective tissue diseases

Background and AimsEarly detection and management of sarcopenia in patients with connective tissue diseases (CTDs) are essential. However, the relationship between the phase angle and sarcopenia in patients with CTDs is unknown. This study investigated the association between the phase angle and sarcopenia in patients with (CTDs) and determined the optimal phase angle cutoff values for the early detection of sarcopenia. MethodsA retrospective cross-sectional study was conducted in 279 hospitalized patients with CTDs undergoing rehabilitation (median age 73.3 years; 80 men and 199 women). Bioimpedance analysis was used to measure the phase angle, and sarcopenia was assessed according to the Asian Working Group for Sarcopenia criteria. ResultsSarcopenia was identified in 134 patients (36 men and 98 women). Patients with sarcopenia had a significantly smaller phase angle than those without sarcopenia. Multivariate analysis revealed that phase angle was significantly associated with sarcopenia after adjusting for confounding factors in each sex. The optimal phase angle cutoff value for identifying sarcopenia was 4.6° for men and 4.3° for women, with area under the curve values of 0.795 and 0.754, respectively. ConclusionPhase angle is a valuable marker for identifying sarcopenia in patients with CTDs. The established phase angle cutoff values of 4.6° in men and 4.3° in women can facilitate the early detection and management of sarcopenia.

Puncture angle on an endoscopic ultrasound image is independently associated with unsuccessful guidewire manipulation of endoscopic ultrasound-guided hepaticogastrostomy: a retrospective study in Japan.

Although endoscopic ultrasound-guided hepaticogastrostomy (EUS-HGS) is performed globally, the procedure remains challenging. Guidewire manipulation is the most difficult step, and there are few reports on the factors associated with unsuccessful guidewire manipulation. This study aimed to assess the significance of the puncture angle on EUS images and identify the most effective guidewire rescue method for patients with unsuccessful guidewire manipulation. We retrospectively enrolled 115 patients who underwent EUS-HGS between May 2016 and April 2022 at two centers. The puncture angle between the needle and the intrahepatic bile duct was measured through EUS movie records. Guidewire manipulation was unsuccessful in 28 patients. Receiver operating characteristic (ROC) curves identified an optimal puncture angle cutoff value of 85° (cutoff value, 85°; area under the ROC curve, 0.826; sensitivity, 85.7%; specificity, 81.6%). Multivariate analysis demonstrated that a puncture angle <85° was a significant risk factor for unsuccessful guidewire manipulation (odds ratio, 19.8; 95% confidence interval, 6.42-61.5; p<0.001). Among the 28 unsuccessful cases, 24 patients (85.7%) achieved successful guidewire manipulation using various rescue methods. The puncture angle observed on EUS is crucial for guidewire manipulation. A puncture angle of <85° was associated with unsuccessful guidewire manipulation.

Evaluation of the Tellurium Dioxide Crystal Shear Acoustic Wave Attenuation at 40-140 MHz Frequency.

The attenuation of slow shear acoustic waves in the (110) plane of tellurium dioxide (TeO2) crystals was investigated. The strong acoustic anisotropy of TeO2 crystals results in a non-uniform acoustic power distribution, which can introduce errors in conventional acousto-optic testing methods. In this study, we propose a general method to measure the acoustic power distribution along the propagation direction of acoustic waves in non-collinear acousto-optic tunable filters (AOTFs). Additionally, we analyze the errors introduced by the non-uniform acoustic field resulting from strong acoustic anisotropy in acousto-optic testing methods. The measurements were carried out for a crystal cutoff angle of 6.5° from the [110] axis, for the ultrasound frequency range from 40 to 140 MHz. The attenuation coefficients were determined and their quadratic dependence on ultrasound frequency was confirmed.

Study on the instability mechanism and control technology of narrow coal pillar in double-roadway layout of Changping mine

To address the issue of roadway support failure in narrow coal pillars under dual-lane layout, this study takes the 4309 working face of Changping Coal Mine as the engineering background and employs theoretical calculations, numerical simulations, and on-site monitoring to investigate the instability mechanisms of narrow coal pillars under dual-lane conditions and to optimize technical solutions. The results indicate that the internal stress distribution within the coal pillar is influenced by the advanced support stress, and as the working face advances, the gradually increasing advanced support pressure causes the vertical stress peak within the coal pillar to shift away from the goaf area. Computational analysis reveals that the vertical stress in the top region of a 6 m narrow coal pillar is 38% higher than that in the bottom region, with an average stress of 16 MPa in the coal pillar. The asymmetric high-level stress concentration within the coal pillar significantly affects its stability. A UDEC (Universal Distinct Element Code) model was established to compare four simulation schemes with cut-off angles of 0°, 5°, 10°, and 15°. Based on the analysis of damage parameters and fracture distribution in the narrow coal pillar roadway, it was concluded that the stability is best when the cut-off angle is 10°. The dense drilling cut-off unloading technology was applied to the 4309 working face of the Changping Mine based on the aforementioned research. On-site monitoring results show that the relative deformation of the roof and bottom plates and the two sides of the test section were controlled within 267 mm and 198 mm, respectively, effectively resolving the deformation and instability issues of the narrow coal pillars.

The angle of the lower portion of the posterior cruciate ligament assists in the diagnosis of partial anterior cruciate ligament tears.

To compare the difference of angle of the lower portion of the posterior cruciate ligament (PCL) measured via magnetic resonance imaging (MRI) in patients with and without partial anterior cruciate ligament (ACL) tears and to investigate the effectiveness of the angle of the lower portion of the PCL in diagnosing partial ACL tears. From January 2022 to December 2022, a cohort of consecutive patients presenting with ACL tears who underwent ACL reconstruction and patients with isolated meniscus tears undergoing arthroscopic surgery were enroled for this study. The angle of the inferior portion of the PCL comprises α and β angles, and the posterior offset of the lateral condyle were measured on the MRI and compared between the partial ACL tear and control groups. Receiver operating characteristic curves, the areas under the curve (AUCs) and the 95% confidence intervals (CIs) were calculated to identify cutoff values for diagnosing partial ACL injuries. Following an assessment of cohort eligibility and matching for age and sex, 100 patients were included in this study. The mean age of the cohort was 46.1 ± 10.3 years. The AUC for the α angle was 0.88 (95% CI, 0.82-0.94), with a sensitivity of 0.74 and specificity of 0.84 for predicting partial ACL ruptures; the α angle cutoff value was 73.6° (diagnostic odds ratio (OR), 14.10; 95% CI, 5.33-37.28). The AUC for the β angle was 0.86 (95% CI, 0.79-0.93), with a sensitivity of 0.64 and a specificity of 0.92 for predicting partial ACL ruptures; the β angle cutoff value was 73.3° (diagnostic OR, 14.54; 95% CI, 5.76-36.68). A small α angle and a large β angle were associated with partial ACL tears. The angle of the distal portion of the PCL was simple to measure and reproducible, enhancing the diagnosis of partial ACL tears. Level III.

Fast Screening Algorithm for Satellites Based on Multi-Constellation System

This paper proposes a fast satellite screening algorithm aimed at the problem of balancing between positioning accuracy and system computing efficiency in a multi-constellation system environment under the Global Navigation Satellite System (GNSS). The algorithm constructs an observation model based on a positioning error for the larger number of satellites under a multi-constellation. The space region is divided based on elevation and azimuth angles to implement the screening algorithm for the solution of the point to be determined. An analysis of the experimental data shows that the average GDOP value of this scheme is 1.835, and the position error of the point to be determined is controlled within 2.5 m when the cut-off altitude angle is 5° and the screening ratio is more than 70%.

Travelling Ionospheric Disturbances detection: a statistical study of detrending techniques, induced period error and near real-time observables

Due to advances in remote sensing of the Earth's Ionosphere through Total Electron Content (TEC) estimates by Global Navigation Satellite System (GNSS) receivers, it is possible to detect and characterize Travelling Ionospheric Disturbances (TIDs) in both post-processing and, to some extent, in near real-time (NRT). A reliable and precise TEC filtering technique must be adopted to characterize waves accurately. Specifically, TEC detrending is widely adopted to extract the amplitude and period of the detected ionospheric waves from the background ionospheric conditions. Therefore, this study aims to understand and compare how different TEC detrending techniques and their settings impact the ability to extract such parameters. We highlight that the novel Fast Iterative Filtering (FIF) and the Savitzky-Golay filter (SGOLAY) techniques are the most reliable overall compared with moving average (MA), multi-order numerical difference (DD), polynomial detrending (POLY) and Finite Impulse response (FIR) band-pass filter (BUTF). Moreover, the impact of general algorithm settings on the extracted TID period is investigated, such as the Ionospheric Piercing Point (IPP) height and elevation cut-off angle, showing that such parameters drastically impact the retrieved period, especially for slower TIDs. Finally, due to the growing interest in real-time (RT) detection and classification of TIDs, the study proposes techniques for accurately estimating the TID amplitude in an NRT scenario. Such NRT techniques are then compared with the widely used post-processing products, such as the calibrated vertical TEC (vTEC), showing a difference that is mostly lower than the typical noise level of GNSS receivers (0.05 TECu).

Diagnostic Abilities of Three-Dimensional Anterior Segment Optical Coherence Tomography in Detecting Angle Closure.

Three-dimensional (3D) angle parameters and cutoff values for detecting angle closure were proposed. The 3D parameters demonstrated excellent diagnostic performance. Certain horizontal two-dimensional (2D) parameters [ie, trabecular iris space area (TISA)-750, angle opening distance (AOD)-750, and AOD-500] can attain similar performance to their high-performing 3D counterparts. To investigate the diagnostic performance of single horizontal 2D versus 3D angle parameters from swept-source anterior segment optical coherence tomography (CASIA2) in detecting angle closure. The cross-sectional study included 118 phakic patients (59 open angles, 59 closed angles). AOD, angle recess area (ARA), and TISA at 250, 500, and 750μm from scleral spur were measured in 360-degree radial-scan images. The 3D information of each measurement was analyzed in 2 patterns: (1) average 3D parameter-the averaged value from 360-degree angle values and (2) estimate 3D parameter-the estimation of surface area of circumferential angle inlet (using AOD) or circumferential angle volume (using ARA and TISA). The areas under the receiver operating characteristic curve [areas under the curve (AUCs)] of eighteen 3D parameters were compared with 2D horizontal parameters. Among 3D parameters, AOD-500 estimate 3D gave the highest AUC (AUC: 0.950, cutoff: 6.09mm 2 ), followed by AOD-750 estimate 3D (AUC: 0.948, cutoff: 8.26mm 2 ). 3D parameters significantly increased the AUC of ARA-250 and TISA-250 (all P < 0.02) compared with the 2D parameters. No significant improvement in AUC was demonstrated for AOD-250 and all parameters at 500 and 750μm. No significant difference in AUC was found among the 6 maximum AUC parameters, which were AOD-750 horizontal 2D, AOD-500 estimate 3D, TISA-750 horizontal 2D, AOD-500 horizontal 2D, AOD-750 estimate 3D, and TISA-750 average 3D. The 3D-angle parameters had high performance in detecting angle closure. However, comparing a horizontal measurement to 3D parameters, the AUC improvement was mostly insignificant.

Risk Factors for Coronary Artery Complications After Prosthetic Pulmonary Valve Implantation in Patients With Congenital Heart Disease.

Coronary artery complications (CACs) in patients who undergoing prosthetic pulmonary valve implantation for congenital heart disease can lead to fetal outcomes. However, the incidence of and risk factors for CACs in these patients remain unknown. A retrospective cohort study was conducted on patients who underwent cardiac computed tomography or invasive coronary angiography after prosthetic pulmonary valve implantation at Seoul National University Hospital from June 1986 to May 2021. Among 341 patients, 25 (7.3%) were identified with CACs, and 2 of them died. Among the patients with CACs, congenital coronary anomalies and an interarterial course of the coronary artery were identified in 11 (44%) and 18 (72%) patients, respectively. Interarterial and intramural courses of the coronary artery were associated with a 4.4- and 10.6-fold increased risk of CACs, respectively. Among patients with tetralogy of Fallot and pulmonary atresia, the aortic root was rotated further clockwise in patients with coronary artery compression compared to those without it (mean [±SD] 128.0±19.9° vs. 113.5±23.7°; P=0.024). The cut-off rotation angle of the aorta for predicting the occurrence of coronary artery compression was 133°. Perioperative coronary artery evaluation and prevention of CACs are required in patients undergoing prosthetic pulmonary valve implantation, particularly in those with coronary artery anomalies or severe clockwise rotation of the aortic root.

Incidence and Characteristics of Knee Ligament and Meniscal Injuries in Patients With Posterolateral Tibial Plateau Fractures.

Anterior cruciate ligament (ACL) tears are commonly seen with concomitant injuries to the posterolateral tibial plateau, while the occurrence of ACL injuries in posterolateral tibial plateau fractures (PTPFs) remains unclear. To (1) explore the incidence of knee ligament (anterior or posterior cruciate ligament, medial or lateral collateral ligament) and medial or lateral meniscus injuries in patients with PTPF and (2) find reliable PTPF-related parameters to predict the risk of knee ligament and meniscal injuries. Cross-sectional study; Level of evidence, 3. Patients diagnosed with PTPF who had computed tomography and magnetic resonance imaging (MRI) data were identified. Morphological parameters of the PTPF were measured on sagittal computed tomography images. Knee ligament and meniscal injuries were assessed using MRI. The association of ACL injuries with meniscal injuries was analyzed. Receiver operating characteristic (ROC) analysis was used to determine the value and cutoff point of the PTPF morphological parameters for diagnosing complete in-substance ACL tears. Overall, 113 patients with PTPF were included. ACL injuries were present in 94 (83.2%) patients, including 43 (38.1%) avulsion fractures and 28 (24.8%) complete in-substance tears. Patients with in-substance ACL tears had a higher incidence of lateral meniscus posterior horn tears compared with the other patients (PBonferroni < .001). ROC analysis revealed that both the fracture depression angle (cutoff point, 25.5°) and the posterior articular surface loss percentage (cutoff point, 37.5%) had a sensitivity >90% and a specificity >80% for the diagnosis of complete in-substance ACL tears. ACL injuries were seen in 83.2% of the study patients. Complete in-substance ACL tears were associated with an increased incidence of lateral meniscus posterior horn tears. Among PTPF parameters, fracture depression angle and posterior articular surface loss percentage showed a high predictive value for the presence of complete in-substance ACL tears, thereby reducing delays in diagnosis and treatment.

Unveiling the distinctive ossification patterns of diffuse idiopathic skeletal hyperostosis and ankylosing spondylitis using computed tomography three-dimensional reconstruction.

To quantitatively analyze the morphological characteristics of osteophytes in DISH and syndesmophytes in AS, and summarize different ossification patterns to help identify the two diseases. Associated factors for new bone formation would be investigated. Fifty patients with DISH and 50 age-, sex-, CT examination site- matched patients with AS were enrolled. Radiographic and clinical data were reviewed. Osteophytes (syndesmophytes) in front of each vertebral body and the corresponding intervertebral disc space were defined as vertebral osteophytes unit (VOU). The volume, angle and location (contralateral, ipsilateral, bilateral) of osteophytes in each VOU were measured and compared between DISH and AS groups. In each VOU, the volume and angle of osteophytes in DISH were significantly larger. The best osteophytes volume and angle cutoff value in predicting DISH was 0.59 cm3 and 40.15°. Contralateral, bilateral, ipsilateral osteophytes were recorded in 59.32%, 36.38%, 4.3% of assessed VOUs in patients with DISH and 64.78%, 29.31%, 5.91% in AS (p‹0.001), respectively. As to ipsilateral osteophytes, the volume was inversely correlated with the center of the vertebral body to the center of the descending aorta (DISH: r = -0.45, p= 0.01; AS: r = -0.83, p‹0.001). Advanced age, disease duration, smoking and overweight contribute to the progression of osteophytes and syndesmophytes. Morphological features of osteophytes are helpful to distinguish DISH with AS. Aortic pulsations inhibit or hinder new bone formation in both DISH and AS. Maintaining normal BMI could postpone osteophytes formation.

Analysis of factors affecting the estimation of the multi-GNSS satellite differential code biases (SDCBs)

The satellite hardware differential code biases (SDCBs) are one of the important factors affecting the accuracy of GNSS-based ionospheric total electron content (TEC) estimation. The accuracy of SDCB estimates is directly influenced by the data processing methodology. To analyze the impact of various factors on multi-GNSS SDCB estimation, we conducted a comprehensive analysis of the number of contributed stations, the data sampling rate, the contributed satellite systems, and the cut-off elevation angle. Two sets of GNSS data obtained from the International GNSS Service (IGS) multi-GNSS experiment (MGEX) network, covering both high and low solar activities during the ascending phase of solar cycle 25, were processed to estimate multi-GNSS SDCBs. The results indicate that the number of contributed stations is the primary factor that influences multi-GNSS SDCB estimation. To achieve a balance between computational efficiency and accuracy, a data sampling rate of 540 s is recommended, which results in a multi-GNSS SDCB root-mean-square (RMS) error of less than 0.01 ns compared to a 60-second sampling rate. The stability of SDCBs is hardly affected by incorporating observations from multiple GNSS systems, and the differences of the standard deviations of SDCBs for quad-, triple- and dual-system solutions are below 0.002 ns. Additionally, the results indicate that the optimal cutoff elevation angle for multi-GNSS SDCB estimation is between 20° and 30°, which ensures the best stability in the estimated multi-GNSS SDCBs.

Anomalous features of the geomagnetic field behavior at the end of the Cretaceous normal superchron based on the results of the study of the Turonian–Santonian in the Southwestern Crimea

In 394 samples characterizing 266 stratigraphic levels in four Turonian–Santonian sections in the Southwestern Crimea, characteristic remanent magnetization components (ChRM) formed at the stage of diagenesis is identified. The data obtained represent the record of the Paleocene geomagnetic variations of high amplitude (rms deviation S = 25.9° with a fixed cut-off angle of 45°, which is about twice as high as the model S for this latitude) in the sediments formed in ~5–6 Ma and are interpreted as anomalous behavior of the geomagnetic field in the Turonian, Coniacian, and Santonian.

A technique for the passband and stopband control of wideband band-pass substrate integrated waveguide (SIW) filters designed with elliptic stepped impedances

In this paper, a design technique based on a stepped impedance synthesis is proposed for the first time for the passband and stopband control of band-pass filters in substrate integrated waveguide (SIW) technology. The structure of the band-pass filters is implemented by means of elliptic patterns etched on the top side of the SIW, which work as impedance inverters. The design method consists of previously mapping the height of the elliptic patterns and the phase shift (cut-off angle) of the SIW lines, connected to the input and output ports of the ellipses, as a function of the passband and stopband characteristics of various stepped impedance SIW filters, to then select the design parameters of the band-pass SIW filter that achieve the desired frequency response. This new approach is applied to the design of two fourth-order Chebyshev stepped impedance band-pass SIW filters with different passband and stopband characteristics. One of the band-pass SIW filters is characterized by a fractional bandwidth FBW1 = 14.5% and a spurious-free range SFR1 = 2.8 GHz, while the other filter has a FBW2 = 22.3% and a SFR2 = 1.55 GHz. Both band-pass filters were designed with a SIW TE10 mode cut-off frequency and a higher passband cut-off frequency fixed at fcTE10 = 2.85 GHz and fc,H = 3.9 GHz, respectively. Electromagnetic (EM) simulations showed that the lower passband cut-off frequency fc,L can vary with respect to fc(TE10) by 13.6% and that the first spurious frequency can appear higher than fc,H by 69.3%. The measurement results agreed well with the EM simulations, thus confirming that this method can be useful to design high-performance wideband Chebyshev stepped impedance band-pass SIW filters with a high degree of control on the passband and stopband characteristics.

An Investigation of the Role of Phase Angle in Malnutrition Risk Evaluation and Clinical Outcomes in Patients with Head and Neck or Brain Tumors Undergoing Radiotherapy

This cross-sectional study aimed to investigate the role of bioelectrical impedance analysis (BIA) and phase angle measurement in assessing malnutrition in head and neck (n = 37) and brain (n = 63) tumor patients received radiotherapy. Common nutritional screening and assessment tests were used to identify malnutrition in the patients. Each patient underwent these tests once, along with phase angle measurement. Additionally, inflammation parameters, including neutrophil lymphocyte ratio (NLR), platelet lymphocyte ratio (PLR), and systemic inflammatory index (SII), were calculated. All study results were correlated with the phase angle cutoff point of 5.72°. The phase angle demonstrated significant correlations with subjective global assessment (SGA), mini nutritional assessment (MNA) scores, BIA parameters, nutritional index, NLR, and SII (p < 0.05). Moreover, in head and neck tumor patients, those with higher standardized phase angle values exhibited significantly better two-year overall survival (32.1% vs. 87.5%, p = 0.006). The phase angle measurement is a convenient, noninvasive, and reproducible method that can complement existing tools for assessing malnutrition risk in radiotherapy patients. The significant correlations observed between the phase angle and various nutritional, inflammation markers and prognosis highlight its potential utility. Further studies incorporating a larger patient cohort will be beneficial in establishing a standard phase angle reference value for cancer patients.

Impact analysis of processing strategies for long-term GPS zenith tropospheric delay (ZTD)

Abstract. Homogenized atmospheric water vapour data are an important prerequisite for climate analysis. Compared with other techniques, GPS has an inherent homogeneity advantage, but it still requires reprocessing and homogenization to eliminate impacts of applied strategy and observation environmental changes where a selection of proper processing strategies is critical. This paper comprehensively investigates the influence of the mapping function, the elevation cut-off angle and homogenization on long-term reprocessing results, in particular for zenith tropospheric delay (ZTD) products, using GPS observations at 44 IGS (International GNSS Service) stations during 1995 to 2014. In the analysis, for the first time, we included the mapping function (the latest Vienna mapping function, VMF3) and exploited homogenized radiosonde data as a reference for ZTD trend evaluations. Our analysis shows that both site position and ZTD solutions achieved the best accuracy when using VMF3 and the 3∘ elevation cut-off angle. Regarding the long-term ZTD trends, homogenization reduced the trend inconsistency among different elevation cut-off angles. ZTD trend results show that the impact of mapping functions is very small, with a maximum difference of 0.19 mm yr−1. On the other hand, the discrepancy can reach 0.60 mm yr−1 using different elevation cut-off angles. Low-elevation cut-off angles (3∘ or 7∘) are suggested for the best estimates of ZTD reprocessing time series when compared to homogenized radiosonde data or ERA5 reference time series.

Retrieval of tropospheric delays from multi-GNSS observations in the polar region: effect factors and performance

Precise point positioning (PPP) technique is practical in estimating the zenith tropospheric delay (ZTD). To comprehensively study the factors affecting its accuracy in the polar region, different elevation cutoff angles for each single system and multi-system combination, different tropospheric mapping functions, tropospheric gradients and also seasonal variations are assessed. Meanwhile, European Centre for Medium-Range Weather Forecasts (ECMWF) products are adopted to validate the accuracy of PPP-derived ZTD. The results show that the root mean square (RMS) value of the estimated ZTD and ECMWF products is around 4 mm when the elevation cutoff angle is set to 10 degrees or less. From the view of system combination, it improves the ZTD accuracy in comparison with each individual system. The dual-system combination has 21.8%, 19.0% and 19.1% improvements in its ZTD accuracy compared with the Global navigation satellite system (GLONASS), Beidou navigation satellite system (BDS) and Galileo satellite navigation (GAL) systems. The four-system combination can reach 7.7% further improvement in ZTD estimation than that of the dual-system. For mapping functions, Vienna mapping function 3 (VMF3) function has the best accuracy among the four mapping functions of Niell mapping function (NMF), global mapping function, VMF1 and VMF3, while NMF does not perform as well as others. Considering the tropospheric gradients could get higher accuracy in ZTD estimation than ignoring them. The tropospheric delay estimated in winter is more accurate than that in summer and specifically the RMS value in winter is about 0.9 mm lower than that in summer. Overall, from investigation the estimation of ZTD in the polar region can be optimally handled with a multi-system and VMF3 mapping function at an elevation cutoff angle of 7°, considering the tropospheric gradients.

Phase angle is associated with sarcopenic obesity in post-stroke patients

Evidence is limited concerning the association between bioimpedance analysis-derived phase angle and sarcopenic obesity. This study examined this association in patients who underwent convalescent rehabilitation after stroke. This cross-sectional study included hospitalized patients with post-acute stroke. The phase angle was measured using a multifrequency bioimpedance analysis. Sarcopenic obesity was diagnosed according to the European Society of Clinical Nutrition and Metabolism/European Association for the Study of Obesity criteria. A multiple linear regression analysis was used to examine the association between the phase angle and sarcopenic obesity after adjusting for confounding factors. A receiver operating characteristic curve was used to calculate the optimal phase angle cutoff value for predicting sarcopenic obesity. A total of 760 patients (median age 71 years; 352 women) were analyzed. The median (interquartile range, 25th and 75th percentiles) phase angle was 4.45° (4.10°, 4.88°). Sarcopenic obesity was diagnosed in 16 (3.9%) men, 18 (5.1%) women, and 34 (4.5%) patients overall. The multiple linear regression analysis showed that sarcopenic obesity (β=-0.185, p=0.017) and sarcopenia (β=-0.121, p=0.012) were significantly and negatively associated with the phase angle. Obesity was not significantly associated with the phase angle (β=-0.078, p=0.094). The optimal cutoff value of the phase angle for diagnosing sarcopenic obesity was 4.29° (sensitivity 0.65, specificity 0.80, area under the curve [AUC] 0.79, 95% CI 0.77-0.87, p<0.001) in men and 3.84° (sensitivity 0.67, specificity 0.84, AUC 0.81, 95% CI 0.79-0.86, p<0.001) in women. The phase angle was associated with sarcopenic obesity, and the cutoff values of the phase angle that could predict sarcopenic obesity were 4.29° for men and 3.84° for women. This simple and practical phase angle-based prediction of sarcopenic obesity can be useful in clinical practice.

Sensitivity of Shipborne GNSS Estimates to Processing Modeling Based on Simulated Dataset.

The atmospheric water vapor is commonly monitored from ground Global Navigation Satellite System (GNSS) measurements, by retrieving the tropospheric delay under the Zenith Wet Delay (ZWD) component, linked to the water vapor content in the atmosphere. In recent years, the GNSS ZWD retrieval has been performed on shipborne antennas to gather more atmospheric data above the oceans for climatology and meteorology study purposes. However, when analyzing GNSS data acquired by a moving antenna, it is more complex to decorrelate the height of the antenna and the ZWD during the Precise Point Positioning (PPP) processing. Therefore, the observation modeling and processing parametrization must be tuned. This study addresses the impact of modeling on the estimation of height and ZWD from the simulation of shipborne GNSS measurements. The GNSS simulation is based on an authors-designed simulator presented in this article. We tested different processing models (elevation cut-off angle, elevation weighting function, and random walk of ZWD) and simulation configurations (the constellations used, the sampling of measurements, the location of the antenna, etc.). According to our results, we recommend processing shipborne GNSS measurements with 3° of cut-off angle, elevation weighting function square root of sine, and an average of 5 mm·h-1/2 of random walk on ZWD, the latter being specifically adapted to mid-latitudes but which could be extended to other areas. This processing modeling will be applied in further studies to monitor the distribution of water vapor above the oceans from systematic analysis of shipborne GNSS measurements.

GPS + Galileo + BDS-3 medium to long-range single-baseline RTK: an alternative for network-based RTK?

AbstractThanks to the development of the real-time kinematic (RTK) algorithm and the emerging Global Navigation Satellite System (GNSS), especially for Galileo and BeiDou-3, reliable positioning accuracy for medium and long-baseline RTK became possible globally. Moreover, with the development of the GNSS receiver hardware, baseline length limitations due to radio-based communications are removed thanks to internet-based communication. In this work, single-baseline RTK, incorporated partial ambiguity resolution with troposphere and ionosphere weighting, using GPS (G), Galileo (E), BeiDou-3 (C3) and multi-GNSS (GE and GEC3), is conducted with real GNSS data of EUREF Permanent GNSS network under three different cutoff angles (10°, 20°, and 30°) for six different lengths of baselines (~50, ~150, ~250, ~350, ~450, and ~550 km). The results show that the multi-GNSS RTK solution significantly contributed to the positioning accuracy and convergence time of the single-system RTK solutions. Based on the results, non-available epoch-wise solutions for the high-degree cutoff angles are more obvious for the single-system RTK, whereas multi-GNSS solutions provide 100% solutions for each cutoff angle and baseline. The results indicate that instantaneous and a few epochs single-epoch ambiguity resolution is feasible for 50, 150, 250 and 350 km baseline lengths for multi-GNSS RTK. Based on the positioning results, horizontal–vertical positioning improvements of multi-GNSS RTK (GEC3) compared with the single-system GPS RTK are found as 50%–37%, 40%–35%, 55%–47%, 53%–54%, 57%–49% and 57%–49% for 50, 150, 250, 350, 450 and 550 km, respectively, under a 10° cutoff angle. For 20° and 30° cutoff angles, the accuracy improvements are much higher. The convergence time improvements (n/e/u) of multi-GNSS RTK (GEC3) compared with the single-system GPS RTK are found as 86/92/75%, 77/67/72%, 75/77/83%, 53/56/52%, 69/49/62%, and 52/45/39% for 50, 150, 250, 350, 450 and 550 km, respectively, under a 10° cutoff angle.