Angular Parameters Research Articles

Postural assessment with the moiré technique in dialyzed patients.

Chronic kidney disease (CKD) patients have limited mobility. A disease that lasts for many years may harm the musculoskeletal system. Knowledge about changes in body posture in these patients is essential in preventing its degradation. In this work, we wanted to draw attention to the changes in the spatial arrangement of the spine and the entire torso in dialysis patients. The study group consisted of 22 female and 32 male dialysis patients. The posture was examined using the moiré projection technique with a portable Computer-Aided System for Posture Assessment which calculated 82 angular and linear parameters of the spine, scapulae, and pelvis in the frontal and sagittal planes. A significant sexual dimorphism was observed for each spine segment. Asymmetry of the scapulae and pelvis was observed in both sexes. Abnormalities may help to establish an accurate exercise plan for dialysis patients. Proper stimulation of the locomotor system can prevent further degradation of body posture.

Deciphering locomotion in reptiles: application of elliptic Fourier transforms to femoral microanatomy

Abstract Reptiles represent one of the most diverse groups of tetrapod vertebrates. Extant representatives of reptiles include lepidosaurs (lizards), testudines (turtles) and archosaurs (crocodiles and birds). In particular, they show an important locomotor diversity with bipedal, quadrupedal and facultatively bipedal taxa. This diversity is accompanied by substantial microanatomical disparity in the limb bones. Although many studies have highlighted the link between locomotion and bone microstructure, the latter has never been quantitatively studied from an angular perspective. Indeed, some taxa show microanatomical heterogeneity in cross-section. Here we show, using elliptic Fourier transforms and statistical analyses integrating phylogeny, how angular microanatomical parameters measured on reptilian femoral cross-sections, such as angular bone compactness, can be related to locomotion in this clade. Although phylogeny appears to have a significant impact on our results, we show that a functional signal exists. In particular, we show that bipeds and quadrupeds present a craniolateral-caudomedial and dorsoventral deficit in bone compactness, respectively. This reflects cross-sectional eccentricity in these directions that we relate to the forces acting upon the femur in different postural contexts. This work contributes to deciphering the complex interplay between phylogeny, femoral cross-sectional microanatomy and locomotion in reptiles.

Effects of different concentrations of methanol on the decomposition of methane hydrate: insights from molecular dynamics simulations

As one of the most promising alternative energy, natural gas hydrate has aroused much attention owing to its controllable exploitation with the aid of chemical injections. Although alcohols are commonly used as promoters for hydrate decomposition, few studies have been carried out to investigate the effect of different concentrations of methanol on methane hydrate decomposition at a molecular level. For the first time, we systematically combined the parameters of angular order parameter (AOP), radial distribution function (RDF), and mean square displacement (MSD) to reveal the role of methanol in the decomposition mechanism of methane hydrates through the molecular dynamics approach. The results demonstrated that methanol concentration had an optimal value for hydrate decomposition, which was 20% methanol solution for the best efficiency for the hydrate decomposition and had been examined by analyzing the parameter of AOP. This can be attributed to the promotion effect of methanol on the deconstruction of the hydrogen bond networks of water molecules and the inhibition effect of methanol on the mass transfer effect of methane diffusion, both of which determined the decomposition of methane hydrates. These effects were further quantitatively evaluated by the structural parameters of RDF and MSD. The obtained results reveal the important influence of methanol concentrations on methane hydrates decomposition on molecular scale, and provide useful guidelines for highly efficient exploitation of natural gas hydrate reservoir.

Identification of the Domain Structure Defects of a Radially Magnetized Rubber-Ferritic Conglomerate.

Modern solutions in materials engineering are designed not just for the improvement in the mechanical or electromagnetic properties of materials but also to begin to fulfill specific functional roles. A good example of such a modern solution is a composite made of steel and rubber-ferritic conglomerate, which is the research object of the article. The composite, when properly magnetized, can act as a magnetic encoder ring for reading the angular displacement, speed, or acceleration parameter. The paper addresses the problem of identifying and assessing the defects of the magnetic encoder ring domain structure in the form of a radially magnetized ring. It discusses the essential types of the ring's degradation, such as mechanical, thermal, and magnetic, and presents problems related to the identification of emerging defects. The conducted research allows a better understanding of the degradation process in the context of magnetic encoder ring reliability. Based on the conducted research on the proposed test stand, it is possible to track the progressive degradation related to each effect. These degradation case analyses consider both quantitative and qualitative changes in the encoder ring's domain structure. The proposed parameters show the possibilities and perspectives for detecting the ring's defects in the early stage of its development. Solely such an approach will allow for proper exploitation and extension of the applicability of this kind of 'intelligent material'. Additionally, the developed parameters for the encoder ring's defects detection can support the progress of rapidly evolving methods for diagnosing mechanical systems based on a signal from such an element.

The impact and estimation of uncertainty correlation for multi-angle polarimetric remote sensing of aerosols and ocean color

Abstract. Multi-angle polarimetric (MAP) measurements contain rich information for characterization of aerosol microphysical and optical properties that can be used to improve atmospheric correction in ocean color remote sensing. Advanced retrieval algorithms have been developed to obtain multiple geophysical parameters in the atmosphere–ocean system, although uncertainty correlation among measurements is generally ignored due to lack of knowledge on its strength and characterization. In this work, we provide a practical framework to evaluate the impact of the angular uncertainty correlation from retrieval results and a method to estimate correlation strength from retrieval fitting residuals. The Fast Multi-Angular Polarimetric Ocean coLor (FastMAPOL) retrieval algorithm, based on neural-network forward models, is used to conduct the retrievals and uncertainty quantification. In addition, we also discuss a flexible approach to include a correlated uncertainty model in the retrieval algorithm. The impact of angular correlation on retrieval uncertainties is discussed based on synthetic Airborne Hyper-Angular Rainbow Polarimeter (AirHARP) and Hyper-Angular Rainbow Polarimeter 2 (HARP2) measurements using a Monte Carlo uncertainty estimation method. Correlation properties are estimated using autocorrelation functions based on the fitting residuals from both synthetic AirHARP and HARP2 data and real AirHARP measurement, with the resulting angular correlation parameters found to be larger than 0.9 and 0.8 for reflectance and degree of linear polarization (DoLP), respectively, which correspond to correlation angles of 10 and 5∘. Although this study focuses on angular correlation from HARP instruments, the methodology to study and quantify uncertainty correlation is also applicable to other instruments with angular, spectral, or spatial correlations and can help inform laboratory calibration and characterization of the instrument uncertainty structure.

Footprint analysis in flatfoot assessment

BACKGROUND: A flatfoot is the most common condition in the practice of a pediatric orthopedist. A flatfoot is primarily diagnosed based on the assessment of the degree of the foot flattening. Along with clinical examination, footprint analysis is often used in practice due to the safety of this study and convenience and ease of implementation.
 AIM: This study aimed to determine how much footprints can correlate with the clinical assessment of flatfoot in children and which footprint indices are the most valuable in flatfoot assessment.
 MATERIALS AND METHODS: The study included the survey results of 76 children aged 715 years of the St. Petersburg 49th school School of Health for 20212022. In this study, anthropometric data, clinical parameters (value of the heel valgus, arch angle, and Friedland index) and footprint indices and angles (Schwartz and Clarke angle, ChippauxSmirak index, Staheli index, Cavanagh and Rodgers index, and Irwin index) were analyzed. In the study, the average values were calculated, and correlation and regression analyses were performed.
 RESULTS: The footprint parameters did not have moderate and strong correlations with clinical parameters. Footprint parameters that assessed the area of the barefoot zone on the footprints (Irwin index and Cavanagh and Rodgers index) showed statistically significant moderate and strong correlations among plantographic parameters. Among linear and angular footprint parameters, the ChippauxSmirak index showed statistically significant moderate and strong correlations.
 CONCLUSIONS: The footprint criteria weakly correlated with the foot shape criteria in a clinical assessment, which does not allow us to interpolate the footprints data to the clinical evaluation data of the foot. The Cavanagh and Rodgers index, Irwin index, and ChippauxSmirak index had statistically significant moderate and strong correlations with other indices, which makes them more valuable in the assessment of feet according to the footprint analysis.

Influence of the excitation polarization on single molecule 3D orientation imaging

Single Molecule Orientation and Localization Microscopy (SMOLM) is gaining an increasing interest in the community of localization microscopy, due to the capability to monitor orientational information in addition to spatial reconstruction. In many cases, molecule’s orientations are not random and their linker to a protein of interest is sufficiently rigid to be able to report orientation information from this protein. While several strategies exist to report single molecule orientation based on polarization splitting and point spread function engineering, the effect of the incident polarization has been often neglected by supposing its effect embedded in the retrieved angular parameters, or by supposing the excitation to be isotropic or the rotational diffusion to be very fast. In this work we quantify the amount of possible bias brought in SMOLM readout due to the incident polarization effect, using analytical derivations. We illustrate this effect experimentally on single molecules attached to a surface in presence of wobbling.

Path Following and Avoiding Obstacle for Mobile Robot Under Dynamic Environments Using Reinforcement Learning

Obstacle avoidance for mobile robot to reach the desired target from a start location is one of the most interesting research topics. However, until now, few works discuss about working of mobile robot in the dynamic and continuously changing environment. So, this issue is still the research challenge for mobile robots. Traditional algorithm for obstacle avoidance in the dynamic, complex environment had many drawbacks. As known that Q-learning, the type of reinforcement learning, has been successfully applied in computer games. However, it is still rarely used in real world applications. This research presents an effectively method for real time dynamic obstacle avoidance based on Q-learning in the real world by using three-wheeled mobile robot. The position of obstacles including many static and dynamic obstacles and the mobile robot are recognized by fixed camera installed above the working space. The input for the robot is the 2D data from the camera. The output is an action for the robot (velocities, linear and angular parameters). Firstly, the simulation is performed for Q-learning algorithm then based on trained data, The Q-table value is implemented to the real mobile robot to perform the task in the real scene. The results are compared with intelligent control method for both static and dynamic obstacles cases. Through implement experiments, the results show that, after training in dynamic environments and testing in a new environment, the mobile robot is able to reach the target position successfully and have better performance comparing with fuzzy controller.

Characterization of Angular RCF Cracks in a Railway Using Modified Topology of WPT-Based Eddy Current Testing

Unavoidably, rolling contact fatigue (RCF) causes natural crack formation in the railhead, leading to rupture. Eddy current testing (ECT) is commonly used to quantify RCF cracks because of its higher sensitivity to a surface flaw, though with limited feature points. This article aims to characterize inclined angular RCF crack parameters in a rail-line material via a modified topology of Wireless Power Transfer (WPT)-based ECT (WPTECT) due to its magnetically coupled resonant for excitation and sensing circuits and utilize multiple resonance responses compared to other ECT. We experimentally designed and evaluated WPTECT and extracted multiple resonances and principal components analysis features to characterize inclined angular RCF cracks. The response minima point feature quantified the crack parameters incomparably; however, the second resonance feature is better than the first resonance. The reconstructed depth, opening width, and angle of the RCF cracks have a maximum correlation, R²-value of 96.4%, 93.1%, and 79.1%, respectively, and RMSE of 0.05mm, 0.08mm, and 6.6⁰, respectively.

Design of Pauci-Adaptive, Spirally Tiled Mirrors for Large Size Optical Vortex Generation

We propose the optical design of an adaptive and flexible 4-quadrant, or N-facet, spirally tiled mirror setup, to generate an optical vortex on large diameter laser systems. From a far-field analysis, we derive the optimal angular parameters that generate the highest contents of the targeted Laguerre-Gaussian mode. The modal purities thus obtained are close to those obtained with standard segmented spiral phase plates or mirrors. The intensity behavior in the focal Rayleigh zone is regular, and the effect of a small laser astigmatism, known to break the circularity of the ring intensity profile at focus, can be corrected. This pauci-adaptive faceted mirror setup appears well suited for use on ultra-high intensity or high energy laser systems.

Design, fabrication and mechanical properties of a 3D re-entrant metastructure

A 3D re-entrant honeycomb structure was designed in a simple configuration by introducing a spatial angular design parameter. Mechanical responses under uniaxial compression of it at constant spatial angle (α) and different re-entrant angles (θ) were investigated both experimentally and theoretically. Designed lattice auxetic structures with high shape fidelity were fabricated using selective laser sintering (SLS) of PA 2200 powder. The produced samples exhibited negative, zero, and positive Poisson's ratios depending on a selected θ value, and their mechanical properties varied over a wide range. Bend- and buckling-dominated deformation mechanisms of the struts have been observed under compression. Additionally, the analytical models of re-entrant honeycomb structures effectively illustrated the quantitative relationships between their mechanical properties (Young’s modulus (E) and Poisson’s ratio) and the design parameter θ. The results presented in this study would provide a reference to the customized design of the porous auxetic structures with unique mechanical properties.

Development of a new low-cost computer vision system for human gait analysis: A case study.

Today, human gait analysis is commonly used for clinical diagnosis, rehabilitation and performance improvement in sports. However, although previous research works in the literature address the use of motion capture systems by means of optoelectronic sensors, Inertial Measurement Units (IMUs) and depth cameras, few of them discuss their conception, guidelines and algorithms for measuring and calculating gait metrics. Moreover, commercially available motion capture systems, although efficient, are cost restrictive for most of the low-income institutions. In this research work, a new computer vision-based system (CVS) for gait analysis is developed and proposed. The aim is to close the gap found in the literature about the design and development of such systems by providing the requirements, considerations, algorithms and methodologies used to develop a gait analysis system with acceptable precision and accuracy, and at low cost. For this purpose, a linear computer vision method based on the non-homogeneous solution of the calibration matrix was used. The spatio-temporal and angular gait parameters were implemented in the proposed system, and compared with those reported in the literature. The denoising of the spatial gait trajectories and the strategies to detect gait events, are also presented and discussed. The results have shown that the proposed system is satisfactory for human gait analysis in terms of precision, computational performance and low cost.

THE INFLUENCE OF ANGULAR PARAMETERS OF THE LOWER JAW ON THE LOCALIZATION OF ITS FRACTURES IN AN ADULT

The frequency of mandibular fractures averages 45–90% of cases of all cases of damage to the bones of the facial skull. Cone-beam computed tomography is the most informative method for diagnosing pathological processes, the nature and degree of damage to the jaws, as well as when planning their surgical treatment, which allows assessing both the nature of the fracture and the value of the main parameters of the jaws necessary to create intraoperative templates. In order to study the sex and age characteristics of the angular parameters of the lower jaw and their interrelation with the nature of its fractures, a study was conducted on 150 bone preparations of the lower jaws and 300 computed tomograms of patients with fractures of the lower jaw. It was established that the angle of the condyle-coronoid line and the angle of the notch were significantly greater in men, and the angle of the lower jaw - in women. It has been proven that with age there is a significant change in the studied angular parameters, which is primarily associated with the loss of teeth. The values of the angle of the lower jaw in elderly and senile people are on average 11,2% higher than in adulthood, and the angle of the condyle-coronoid line significantly decreases with age by an average of 7°. It has been proved that when the value of the angle of the lower jaw is close to the right one, the fracture line is significantly more often localized in the area of the incisors in 31,7% of cases of observations, the canines and premolars - in 20,8% of cases of observations. Fractures in the area of the condylar process in women, unlike men, in the overall structure of fractures exceed the frequency of fractures in the area of its angle. Thus, the angular parameters of the lower jaw have pronounced gender and age differences, which have a direct impact on the nature and localization of fractures of this bone. As a result, the greater the angle of the lower jaw, the greater the likelihood of its single fractures, the smaller the angle of the condyle-coronoid line, the greater the likelihood of fractures in the area of the condylar process.

Evaluation of motor adaptation of healthy persons according to space-time kinematics data

An important problem of modern clinical biomechanics is to identify complex movement markers that make it possible to evaluate complex motor adaptive reactions regardless of age, gender, and anthropometric deviations. The purpose of the present study was to develop a method for analysis of human motor adaptive reactions based on calculating specific biomechanical markers obtained by performing diverse kinematic tests. The study involved 90 volunteers with a right-leading kinematic side at an age of 18.8 [16.8/20.8] years, with a height of 171.8 [179.2/164.8] cm, a body weight of 65.3 [76.6/58.5] kg, and the ratio of men and women – 5 : 4. During the study, all participants underwent biomechanical analysis using the TESLASUIT remote motion capture suit and performing diverse kinematic tests. In the course of the study, a new method for analyzing human motor adaptive reactions was developed. It is based on calculating specific time markers of the active phase, average angular deviation markers, and inertial kinematic markers. All markers are calculated after each kinematic tests “frontal stability”, “sagittal stability”, “spatial orientation”, and “stimulus identification”. Our survey revealed that specific (p < 0.001) markers of the first test are the time indicators of the active phase, the markers of the second and fourth tests are associated with the average angular deviation parameters, and the specific indicators of the third test can be the inertial kinematics of thighs, legs, and feet.

Accuracy of virtual surgical planning in mandibular reconstruction: application of a standard and reliable postoperative evaluation methodology

ObjectiveThe purpose of this study was to determine the accuracy of virtual surgical planning for mandibular reconstruction, along with the implementation of a postoperative evaluation methodology.Materials and methodsThe study is a prospective case series for computer-assisted mandibular reconstruction surgery. Analysis of the degree of agreement between virtual measurements and postoperative actual outcomes was performed. The reliability of the proposed evaluation methodology was assessed and analyzed using the Inter-Class Coefficient (ICC) test. Statistical significance was set at the 5% level.ResultsNine consecutive patients were selected. The analysis of all angular and linear parameters reported a highly statistically significant degree of agreement between the preoperative and postoperative measurements (P < 0.001). Furthermore, an extreme degree of reliability was reported when the evaluation methodology was scrutinized (ICC = 0.9).ConclusionThe excellent degree of agreement between the virtual plan and the actual outcome reported in this study validated the surgical accuracy of virtually assisted mandibular reconstruction. This study pointed out the reliability and reproducibility of the standardized evaluation protocol in an attempt to obtain a tolerable value for the acceptable postoperative results regarding the accuracy of computer-assisted surgery.

Dramatic relativistic effects on the ns dipole angular distribution asymmetry parameter, βns , of heavy and superheavy elements

A theoretical study of the dipole photoelectron angular distribution asymmetry parameter, β, of the 6s, 5s and 4s subshells has been conducted for a range of closed-shell heavy, Hg (Z = 80), Rn (Z = 86), Ra (Z = 88) and superheavy, No (Z = 102), Cn (Z = 112), Og (Z = 118), Ubn (Z = 120) elements to understand the deviation of β from the nonrelativistic value of 2 owing to relativistic effects. It was found that the deviation, strongest in Cooper minimum regions, persists over all energy for all ns subshells, and the deviations increase with Z. Three levels of relativistic calculations were performed in order to pinpoint the particular interactions responsible for the details of the behavior of the ns β’s as functions of energy, n, and Z and, in addition to the effects of the (relativistic) spin–orbit interaction, interchannel coupling was found to be of crucial importance in the determination of the β parameter in most of the situations studied.

Violating the chaos bound in five-dimensional, charged, rotating Einstein-Maxwell-Chern-Simons black holes

We study the equilibrium orbit and violation of chaos bound of particle motion in the five-dimensional, charged, rotating Einstein-Maxwell-Chern-Simons black hole. Through numerical analysis, we find that the relative distance between the equilibrium orbit and the event horizon decreases with four independent parameters (particle's charge, black hole's charge and angular momentum parameters (a, b)) increase in specific regions, respectively. By adjusting the ratio of particle's charge to its angular momentum, we find that the equilibrium orbit can be close to the event horizon. We also find that the chaos bound of Einstein-Maxwell-Chern-Simons black holes can be greatly violated under certain parameter conditions. At the near horizon, the violation of chaos bound becomes more likely to occur.

The Male Eyebrow and Eyelid: An Anthropometric Analysis of White Professional Models.

Surgical lift of eyebrows is one of the most efficient facial rejuvenation methods. Although the popularity of those procedures seems to be increasing among men, little is known about aesthetically pleasant male eyebrow shape and position. Semiautomatic photogrammetric analysis of 300 professional White male models of assumed age (18 to 39 years old) was performed. The assessment was conducted in two sessions, using A.I.D. software. A set of linear, angular, and surface area morphometric parameters of the periorbital region was measured. A total of 600 periorbital regions were quantitatively evaluated. Statistical analysis showed high interrater reliability for all three types of measurements. The mean width of the eyebrow was found to be 47.28 ± 4.55 mm. The male eyebrow was flat and low-located, overlying the orbital rim. The apex was located at the lateral two-thirds of the brow's width. The vertical distance between the eyebrow's peak and the hairline was 51.3 ± 7.15 mm. In addition, averaged body contours were generated using the A.I.D. software, enabling graphic summarization of facial outline and periorbital contours of all analyzed subjects in the form of a single figure. Based on the aesthetic preferences of several leading modeling agencies, a concept of the ideal eyebrow for White men was created. The collected morphometric data on the periorbital region may guide the surgical rejuvenation attempts of achieving youthful and natural brow contours. It may also aid its reconstruction using hair transplant techniques.

Analysis of Components of Upper Cervical Lordosis in Asymptomatic Lordotic and Kyphotic Subjects

Upper cervical lordosis (CL) can be divided into 2 components: C2 slope (C2S) and McGregor slope (MGS) or C0-1 and C1-2 angles. The aim of this study was to investigate the components of upper CL in asymptomatic kyphotic and lordotic subjects. CL, C0-2 Cobb angle, MGS, C2S, C1 Slope, C0-1 Cobb angle, C1-2 Cobb angle, T1 slope angular parameters, and the C2-7 sagittal vertical axis distance of 78 asymptomatic subjects were measured. Sixty subjects had lordotic curvature and 18 had kyphotic curvature. There was a significant difference between the kyphotic and lordotic groups in all parameters, except for C0-1 Cobb angle and C2-7 sagittal vertical axis. In lordotic subjects, MGS and C2S accounted for 58% and 42% of the C0-2 angle, whereas in kyphotic subjects, 86% of C0-2 was accounted for by C2S. There was a strong negative correlation between C2S and MGS. In asymptomatic subjects, as CL decreases, MGS decreases, C2S increases, and the C0-2 angle turns down on the horizontal plane to maintain the horizontal gaze. Turning down the C0-2 angle is more important than its value for maintaining horizontal gaze; thus, the slopes (MGS and C2S) can better represent the upper and lower cervical alignment than angle values can. The relationship between upper and lower cervical alignment should be evaluated in terms of slope angles rather than simple angles. The lack of significant difference between the C0-1 angles in the kyphotic and lordotic groups suggests that only the C1-2 angle is involved in the compensatory mechanism for the horizontal gaze.

Joint angular-frequency distribution estimation via spatial-temporal sparse sampling and low-rank matrix recovery

This paper is committed to the joint angular-frequency distribution (JAFD) estimation for incoherently distributed wideband (IDW) sources by using spatial-temporal sparse sampling (STSS). The STSS increases dramatically the degrees of freedom (DOFs) of the measure system, and can solve the ambiguity problem between angular and frequency parameters. Then, it is observed that the discrete representation of the JAFD gives rise to a helpful low-rank matrix. To estimate the JAFD for IDW sources, a rank minimization problem is further formulated as the modified Schatten-p norm minimization (MSpNM) problem, which can be resolved efficiently by the accelerated iterative singular value thresholding algorithm (AISVTA). Compared with traditional methods based on spatial and temporal Nyquist sampling (STNS), the proposed method based on STSS reduces the sampling rate requirement on hardware and provides better JAFD estimation precision. Experiment simulations indicate its effectiveness and confirm the superior performance of the proposed method based on STSS.