Angular Location Research Articles

Earliest location of glaucomatous retinal nerve fibre layer damage is determined by intact baseline RNFL thickness profile

Background/aimsTo identify whether an intact retinal nerve fibre layer (RNFL) thickness profile could determine the location of the earliest RNFL defect in glaucoma.MethodsRetrospective longitudinal cohort study of patients with initial...

Tunable enhancement of the cylindrical Luneburg lens focusing ability with the aid of a conformal graphene strip

We consider the plane wave focusing characteristics of the layered cylindrical Luneburg lens equipped with a conformal strip of graphene, in the H-polarization case. The angular width and location of the strip is arbitrary, and its surface impedance is characterized with the aid of the quantum-physics Kubo formalism. We use a mathematically accurate full-wave analytical regularization technique, which is based on the explicit inversion of the problem static part and yields a Fredholm second-kind matrix equation. This guarantees the convergence of the resulting meshless numerical algorithm. We compute the focusing ability of a microsize lens as a function of the frequency in the wide range up to 60 THz. This analysis shows that a graphene strip, placed into the focal area of the Luneburg lens, enhances its focusing ability at the resonance frequency of the strip plasmon mode proportionally to the quality factor. This frequency is defined by the strip width and is tunable with the aid of graphene’s chemical potential.

Angular Location of the $$n^{th}$$ Einstein Ring at Large n

Angular Location of the $$n^{th}$$ Einstein Ring at Large n

P‐49: Angular Dependent Point Spread Function Analysis for Virtual Reality Head Mounted Displays

We demonstrate a point spread function method for measuring the angular dependence of the spatial resolution of a virtual reality head mounted display. The angular dependence of spatial resolution of the imaging detector was characterized to remove the detector's contribution at each angular location measured on the VR HMD. This method allows measuring the twodimensional spatial resolution and modulation transfer function.

Experimental and numerical investigations of the water surface profile and wave extrema of supercritical flows in a narrow channel bend

Supercritical flows in channel bends, e.g., in steep streams, chute spillways, and flood and sediment bypass tunnels (SBTs), experience cross-waves, which undulate the free surface. The designs of these hydraulic structures and flood protection retaining structures in streams necessitate computing the locations and water depths of the wave extrema. This study numerically and experimentally investigates the water surface profiles along the sidewalls, the wave extrema flow depths, and their angular locations in a narrow channel bend model of the Solis SBT in Switzerland. The 0.2 m wide and 16.75 m long channel has a bend of 6.59 m radius and 46.5° angle of deviation. The tested flow conditions produced Froude numbers ≈ 2 and aspect ratios ranging from 1.14 to 1.83. Two-phase flow simulations were performed in OpenFOAM using the RNG k–ε turbulence closure model and the volume-of-fluid method. The simulated angular locations of the first wave extrema and the corresponding flow depths deviate marginally, within ± 6.3% and ± 2.1%, respectively, from the experimental observations, which signifies good predictions using the numerical model. Larger deviations, especially for the angular locations of the wave extrema, are observed for the existing analytical and empirical approaches. Therefore, the presented numerical approach is a suitable tool in designing the height of the hydraulic structures with bends and conveying supercritical flows. In the future, the model’s application shall be extended to the design of the height and location of retaining walls, embankments, and levees in steep natural streams with bends.

Peripheral Binocular Imbalance in Anisometropic and Strabismic Amblyopia.

Individuals with amblyopia experience central vision deficits, including loss of visual acuity, binocular vision, and stereopsis. In this study, we examine the differences in peripheral binocular imbalance in children with anisometropic amblyopia, strabismic amblyopia, and typical binocular vision to determine if there are systematic patterns of deficits across the visual field. This prospective cohort study recruited 12 participants with anisometropic amblyopia, 10 with strabismic amblyopia, and 10 typically sighted controls (age range, 5-18years). Binocular imbalance was tested at 0°, 4°, and 8° eccentricities (4 angular locations each) using band-pass filtered Auckland optotypes (5 cycles per optotype) dichoptically presented with differing contrast to each eye. The interocular contrast ratio was adjusted until the participant reported each optotype with equal frequency. Participants with anisometropic and strabismic amblyopia had a more balanced contrast ratio, or decreased binocular imbalance, at 4° and 8° eccentricities as compared with central vision. Participants with strabismic amblyopia had significantly more binocular imbalance in the periphery as compared with individuals with anisometropic amblyopia or controls. A linear mixed effects model showed a main effect for strabismic amblyopia and eccentricity on binocular imbalance across the visual field. There is evidence of decreased binocularity deficits, or interocular suppression, in the periphery in anisometropic and strabismic amblyopia as compared with controls. Notably, those with strabismic amblyopia exhibited more significant peripheral binocular imbalance. These variations in binocularity across the visual field among different amblyopia subtypes may necessitate tailored approaches for dichoptic treatment.

Validating Thai translations of perceptual soundscape attributes: A non-Procrustean approach with a Procrustes projection

Measurement of a psychological construct across populations without a common linguistic medium often necessitates the development of multiple translations of the psychometric tool across multiple languages, dialects, or other population-specific variations. In this follow-up (Stage 2) study, a listening test using a shared set of 27 stimuli from the Soundscape Attribute Translation Project (SATP) was conducted with Thai-speaking participants using the set of Thai translations of the eight perceptual affective quality (PAQ) descriptors selected in earlier (Stage 1) work through a structured evaluation questionnaire. Principal component analysis was performed on the listening test data to obtain a rank-two reduction of the responses with maximal explained variance. In order to align the principal component space to the two-dimensional circumplex space, this work presents a simple and numerically stable method based on the orthogonal Procrustes projection, to find the optimal two-dimensional orthogonal transform that aligns the first two principal components with the axes corresponding to Pleasantness and Eventfulness as defined in ISO/TS 12913-3:2019. Analysis of the listening test responses indicated good to excellent interrater reliability, reflecting the general comprehensibility of the translations to laypersons. Subsequent analyses yielded a two-dimensional projection with ▪ explained variance and near-perfect alignment of the composite Pleasantness and Eventfulness axes. Angular locations of the individual translated PAQs are located within ▪ of their theoretically ideal locations and preserve angular ordering, albeit with imperfect equiangularity. Cross-analysis against the results from Stage 1 showed that the structured evaluation may be partially useful in anticipating potential imperfections of the PAQ translations and their angular locations in Stage 2.

Application of 3D Imaging for Analyzing the Chip Groove Shapes of Cutting Inserts

An effective chip formation process is significant for an efficient metal-cutting process. Long continuous chips can lead to scratches on the machined surface, increasing the risk to operator safety and stability of the machining process. The use of chip grooves on cutting inserts allows for control of the chip formation and breaking process during machining. The shape of the rake surface and the design of the chip groove also affect the efficiency of the machining process. The article presents the use of 3D imaging to analyze changes in the selected chip groove shapes depending on the cutting depth ap = 0.10, 0.25, and 0.50 mm and the angular location of the cutting insert relative to the machined surface of the workpiece (i.e., major cutting-edge angle K = 60° and K = 90°). The analysis methodology was based on the use of 3D image registration and surface shape modeling. In the analysis based on the 3D imaging presented, the novelty was the adaptation of methods typically used to map and model the terrain surface, which have not been used previously in cutting processes. The evaluation of the shape of the chip groove surface was carried out using, e.g., watershed maps and 3D surface maps. The obtained results indicated a significant influence of the cutting depth and major cutting-edge angle on the surface shape, profile, and length of the chip former; chip groove volume; and the theoretical contact area of the formed chip with the cutting insert. It was observed that for small depths of cut, i.e., ap < 0.25 mm, the chip-curling process may be difficult due to the flattened shape of the rake surface. In addition, the influence of the convexity of the rake surface of the cutting insert on the chip formation process was demonstrated. The results of the experimental research that verified the conclusions are presented. The developed results may be useful in the process of selecting the parameters and conditions of the metal finishing through use of tools with a shaped rake surface.

Creep rapture of plastic pipes: Effect of eccentricity, residual stress, and circumferential orientation

Plastic pipes made of high density polyethylene material with known geometric eccentricities and residual stresses were subjected to long term hydrostatic stress until rupture at different stresses and temperatures. Cooling and crystallisation rates of the pipe wall during the extrusion process were simulated along the production line. Crystallisation profile and circumferential orientation of polymer chains were measured at different angular locations and thicknesses around the circumference. It was shown that the plasticity-controlled rapture times of plastic pipes are significantly depended on geometric eccentricity as a result of re-distribution of residual stresses and circumferential orientation.

Azimuthal phase-dependent electromagnetically induced transparency and the generation of spatial light in a microwave-assisted four-level Y-type system

We present an azimuthal phase-dependent scheme to study the spatially dependent electromagnetically induced transparency (EIT) and the generation of spatial light in a closed-loop four-level Y-type system. A structured control beam and a microwave (MW) field are adopted in the closed-loop structure. Interestingly, the weak non-vortex probe beam responses explicitly depend on the orbital angular momentum (OAM) of the control beam along with the MW-assisted quantum interference. The regions of spatially dependent EIT are demonstrated at different azimuthal angles. It is found that the intensity of the structured control beam and the relative phase arising out of the beams participating in the closed-loop can be used as the controlling knobs to tailor the shape and the angular location of the spatially dependent EIT.

Through the wall human heart beat detection using single channel CW radar.

Single-channel continuous wave (CW) radar is widely used and has gained popularity due to its simple architecture despite its inability to measure the range and angular location of the target. Its popularity arises in the industry due to the simplicity of the required components, the low demands on the sampling rate, and their low costs. Through-the-wall life signs detection using microwave Doppler Radar is an active area of research and investigation. Most of the work in the literature focused on utilizing multi-channel frequency modulated continuous wave (FMCW), CW, and ultra-wideband (UWB) radar for their capability of range and direction of arrival (DOA) estimation. In this paper, through-the-wall single-subject and two-subject concurrent heart rate detection using single-channel 24-GHz CW radar leveraged with maximal overlap discrete wavelet transform (MODWT) is proposed. Experimental results demonstrated that the repetitive measurement of seven different subjects at a distance of 20cm up to 100cm through two different barriers (wood and brick wall) showed an average accuracy of heart rate extraction of 95.27% for varied distances (20-100cm) in comparison with the Biopac ECG acquisition signal. Additionally, the MODWT method can also isolate the independent heartbeat waveforms from the two subjects' concurrent measurements through the wall. This involved four trials with eight different subjects, achieving an accuracy of 97.04% for a fixed distance of 40cm from the Radar without estimating the angular location of the subjects. Notably, it also superseded the performance of the direct FFT method for the single subject after 40cm distance measurements. The proposed simpler architecture of single-channel CW radar leveraged with MODWT has several potential applications, including post-disaster search and rescue scenarios for finding the trapped, injured people under the debris, emergency evacuation, security, surveillance, and patient vital signs monitoring.

Investigation of convective heat transfer in a cold flow pebble bed nuclear reactor using advanced pebble probe heat transfer sensor

The aim of this study was to investigate the local heat transfer coefficients between the pebbles and the coolant gas in a PBR using an advanced measurement technique that consists of a heated pebble probe, a micro-foil heat flux sensor mounted flush on the surface of the heated pebble probe, and a thermocouple in the center of the bed void in front the sensor. In this work, the local heat transfer coefficients were derived at various axial levels, radial and angular locations and at different superficial inlet gas velocities that cover both transitional and turbulent flow conditions. The local heat transfer coefficients were found to be 22-32%, 34-39%, and 18-20% higher near the wall at superficial inlet gas velocities of 0.3,1.2, and 2m/s, respectively. This is due to higher volumetric flow at the wall where larger void in the pebble bed exists compared to the center region of the bed where the flow of the gas in the packed bed follows the least resistance path. Large deviations were obtained between the experimental overall heat transfer coefficients in the bed and the predictions of seven correlations that were selected from the literature. Furthermore, these correlations cannot predict the local heat transfer coefficients inside the PBR. This necessitates the development of new correlations for the prediction of the local heat transfer coefficients using the data obtained in this work. A pseudo-3D correlation was developed and was found to provide predictions that are in good agreement with the experimental values for the conditions used, with an averaged absolute relative error (AARE) of 3.33% at high Reynolds numbers for our operating and design conditions.

Laminar Torsional Couette Flow Over a Wavy Disk

Abstract A parametric study of laminar torsional Couette flow between a rotating flat disk and a stationary wavy disk is conducted using computer simulations. The waviness of the stationary disk, characterized by the parameter wave slope (WS), is increased across four cases to evaluate its influence. The resulting flow field is significantly different from torsional Couette flow between flat disks. Shear stress and pressure on the flat and wavy disks are sinusoidal with the same spatial frequency as the undulation. Their averages over one wavelength remain unaffected by the increase in WS. However, this is not the case with their amplitudes. A critical layer is observed approximately at a distance of 70% radius of the disk across which the effect of WS on shear amplitude is inverted. Furthermore, the sinusoidal shear on the flat disk is observed to be in destructive phase with respect to the shear on wavy disk. This is corroborated by the concave/convex distortion of the height-wise tangential velocity profile across the undulation. Alternately, the net radial velocity becomes biased either toward or away from the axis depending on angular location with respect to the undulation. The effect of increasing WS on the tangential velocity is in the form of small increments to the curvature of its height-wise profile, while the axial velocity, though it is orders of magnitude smaller than the tangential velocity, increases substantially with increase in WS.

Rotating black hole in Kalb–Ramond gravity: Constraining parameters by comparison with EHT observations of Sgr A* and M87*

This article deals with the study of some properties of the static and rotating black holes in Kalb–Ramond gravity in four dimensional spacetime. First, we discuss the action of the corresponding theory and the static black hole metric. Then we investigate the light sphere for the static black hole by using the Hamiltonian formalism and the corresponding linear radius of the shadow, angular velocity and Lyapunov exponent. For the rotating black hole, we discuss the horizon structure. Moreover, we study the effective potential to discuss the structure of null sphere and unstable circular null orbits around the rotating black hole. The properties such as energy emission rate and distortion are calculated and analyzed by using the numerical data for the shadows calculated by appropriately chosen parametric values for two different angular locations of the observer off the equatorial plane. We also obtain the constraints on the black hole parameters by comparing the shadow sizes of the black hole in Kalb–Ramond gravity and the supermassive black holes M87* and Sgr A*. Finally, we investigate the effect of mass, energy, angular momentum and the black hole parameters on the center of mass energy of two colliding particles that are accelerated in the vicinity of the black hole.

Synthesis of Elliptical Antenna Array using Hybrid SSWOA Algorithm

In terms of research, the elliptical antenna arrays (EAA) synthesis is relatively novel. As it does not have to be circular in construction, this novel synthesis can maneuver the primary beam in the right direction, making it easier to realize. The amplitude and angular location of the ellipse, as well as the eccentricity of the ellipse, are all taken into account in the optimization process. The proposed hybrid algorithm is the SSWOA (Salp Swarm Whale Optimization Algorithm), which combines the Salp Swarm Optimization Algorithm (SSA) with the Whale Optimization Algorithm (WOA). The SSA algorithm serves as a guide, while the WOA algorithm serves as a helper in this method. We discover that optimization has a faster convergence time and high convergence accuracy when considering the benefits of SSA and WOA and applying them to the synthesis of antenna array layouts. If Griewank, Rosenbrock, Sphere, and Rastrigin test functions are used, it’s worth noting that the hybrid method outperforms both WOA and SSA.

Detection of Cosmological 21 cm Emission with the Canadian Hydrogen Intensity Mapping Experiment

We present a detection of 21 cm emission from large-scale structure (LSS) between redshift 0.78 and 1.43 made with the Canadian Hydrogen Intensity Mapping Experiment. Radio observations acquired over 102 nights are used to construct maps that are foreground filtered and stacked on the angular and spectral locations of luminous red galaxies (LRGs), emission-line galaxies (ELGs), and quasars (QSOs) from the eBOSS clustering catalogs. We find decisive evidence for a detection when stacking on all three tracers of LSS, with the logarithm of the Bayes factor equal to 18.9 (LRG), 10.8 (ELG), and 56.3 (QSO). An alternative frequentist interpretation, based on the likelihood ratio test, yields a detection significance of 7.1σ (LRG), 5.7σ (ELG), and 11.1σ (QSO). These are the first 21 cm intensity mapping measurements made with an interferometer. We constrain the effective clustering amplitude of neutral hydrogen (H i), defined as , where ΩH i is the cosmic abundance of H i, b H i is the linear bias of H i, and 〈f μ 2〉 = 0.552 encodes the effect of redshift-space distortions at linear order. We find for LRGs (z = 0.84), for ELGs (z = 0.96), and for QSOs (z = 1.20), with constraints limited by modeling uncertainties at nonlinear scales. We are also sensitive to bias in the spectroscopic redshifts of each tracer, and we find a nonzero bias Δ v = − 66 ± 20 km s−1 for the QSOs. We split the QSO catalog into three redshift bins and have a decisive detection in each, with the upper bin at z = 1.30 producing the highest-redshift 21 cm intensity mapping measurement thus far.

Comparing retinotopic maps of children and adults reveals a late-stage change in how V1 samples the visual field

Adult visual performance differs with angular location –it is better for stimuli along the horizontal than vertical, and lower than upper vertical meridian of the visual field. These perceptual asymmetries are paralleled by asymmetries in cortical surface area in primary visual cortex (V1). Children, unlike adults, have similar visual performance at the lower and upper vertical meridian. Do children have similar V1 surface area representing the upper and lower vertical meridian? Using MRI, we measure the surface area of retinotopic maps (V1-V3) in children and adults. Many features of the maps are similar between groups, including greater V1 surface area for the horizontal than vertical meridian. However, unlike adults, children have a similar amount of V1 surface area representing the lower and upper vertical meridian. These data reveal a late-stage change in V1 organization that may relate to the emergence of the visual performance asymmetry along the vertical meridian by adulthood.

Optic disc tilt and rotation effects on positions of superotemporal and inferotemporal retinal nerve fibre layer peaks in myopic Caucasians

ABSTRACT Clinical relevance In myopic eyes, the optic disc may become tilted and rotated, making glaucoma diagnosis more difficult. Background To determine the presence of tilted optic disc, the degree of optic disc rotation, and their effects on the angular location of superotemporal and inferotemporal retinal nerve fibre layer (RNFL) peaks in healthy myopic Caucasians. Methods Non-glaucomatous healthy myopic Caucasian eyes with an axial length > 24 mm were evaluated. ImageJ was used to quantify optic disc tilt and torsion on red-free fundus photography. The RNFL was scanned using spectral-domain optical coherence tomography. The angle of the superotemporal and inferotemporal peaks with the vertical-horizontal meridian was measured. Results Fifty-four eyes of 54 individuals were evaluated. The axial length was correlated with the angular location for both the superotemporal (r = −0.549, p < 0.001) and inferotemporal (r = −0.415, p = 0.002) RNFL peaks; they were placed more temporally in eyes with higher axial lengths. For each 1 mm increase in axial length, the angle between the superotemporal peak and the temporal horizontal meridian decreased by 3.976°, and the angle between the inferotemporal apex and the temporal horizontal meridian decreased by 3.028°. The angle between the inferotemporal peak and the temporal horizontal meridian decreased by 0.231° for each 1° increase in optical disc torsion (R2 = 0.09 Regression coefficient = −0.231, p = 0.027). Conclusions The temporal shift of superior and inferior peaks, the thickening of temporal and nasal RNFL, the presence of tilted optic disc, and optic disc rotation may cause misinterpretation of the RNFL in myopic Caucasians. When evaluating peripapillary RNFL thickness in myopic individuals, it would be better to consider these to avoid misinterpretation.

Multicolor imaging compared with red-free fundus photography in the detection of glaucomatous retinal nerve fiber layer thinning

BackgroundTo compare the ability of multicolor imaging (MCI) with red-free fundus photography (RFP) to detect glaucomatous retinal nerve fiber layer (RNFL) thinning. MethodsA total of 127 eyes of 79 patients with glaucoma underwent MCI using blue light, RFP, and circumpapillary optical coherence tomography (OCT) scanning on the same day. Angular location and width of the RNFL defects (RNFLDs) identified on the MCI and RFP were independently measured, and compared with those of RNFL thinning indicated by abnormal color codes on OCT. ResultsThe angular location and width of the RNFLDs determined by both MCI and RFP were well correlated with those of RNFL thinning determined by OCT (all P ≤ 0.013). The correlation of angular width with OCT was significantly stronger for MCI than for RFP (R = 0.708 vs. R = 0.616, P = 0.009). The superiority of MCI to RFP in the detection of OCT-determined RNFL thinning was significant in the inferior (P = 0.025) and marginally significant in the superior (P = 0.084) hemisectors. Thinner RNFL and longer axial length were significantly associated with better visualization of RNFLD by MCI than by RFP, respectively in the superior (OR = 0.948, P = 0.048) and inferior (OR = 1.490, P = 0.012) hemisectors. ConclusionsRNFLD on MCI correlated well with OCT measurement of RNFL thinning in eyes with glaucoma. MCI performed better than conventional RFP in the detection of OCT-determined RNFL thinning, specifically in eyes with thinner RNFL and those with myopia. MCI may be more useful than conventional RFP in evaluating glaucomatous RNFL thinning.

Tracing Hot Spot Motion in Sagittarius A* Using the Next-Generation Event Horizon Telescope (ngEHT)

We propose the tracing of the motion of a shearing hot spot near the Sgr A* source through a dynamical image reconstruction algorithm, StarWarps. Such a hot spot may form as the exhaust of magnetic reconnection in a current sheet near the black hole horizon. A hot spot that is ejected from the current sheet into an orbit in the accretion disk may shear and diffuse due to instabilities at its boundary during its orbit, resulting in a distinct signature. We subdivide the motion into two different phases: the first phase refers to the appearance of the hot spot modeled as a bright blob, followed by a subsequent shearing phase. We employ different observational array configurations, including EHT (2017, 2022) and the next-generation Event Horizon Telescope (ngEHTp1, ngEHT) arrays, with several new sites added, and make dynamical image reconstructions for each of them. Subsequently, we infer the hot spot angular image location in the first phase, followed by the axes ratio and the ellipse area in the second phase. We focus on the direct observability of the orbiting hot spot in the sub-mm wavelength. Our analysis demonstrates that for this particular simulation, the newly added dishes are better able to trace the first phase as well as part of the second phase before the flux is reduced substantially, compared to the EHT arrays. The algorithm used in this work can be easily extended to other types of dynamics, as well as different shearing timescales. More simulations are required to prove whether the current set of newly proposed sites are sufficient to resolve any motions near variable sources, such as Sgr A*.