Angular Shift Research Articles

Goos-Hänchen shift for an Airyprime beam.

We propose a comprehensive theory to analyze the Goos-Hänchen (GH) shift for an arbitrarily polarized Airyprime beam reflected at the air-dielectric interface. We derive general expressions for the spatial and angular GH shifts and establish a close relationship between the GH shift of the Airyprime beam and the GH shift of the Airy beam. We also predict the novel optical effects of a significantly enhanced spatial GH shift and an almost disappeared angular GH shift when the horizontally polarized Airyprime beam is reflected near Brewster's angle.

Whole Organ Volumetric Sensing Ultrasound Localization Microscopy for Characterization of Kidney Structure.

Glomeruli are the filtration units of the kidney and their function relies heavily on their microcirculation. Despite its obvious diagnostic importance, an accurate estimation of blood flow in the capillary bundle within glomeruli defies the resolution of conventional imaging modalities. Ultrasound Localization Microscopy (ULM) has demonstrated its ability to image in-vivo deep organs in the body. Recently, the concept of sensing ULM or sULM was introduced to classify individual microbubble behavior based on the expected physiological conditions at the micrometric scale. In the kidney of both rats and humans, it revealed glomerular structures in 2D but was severely limited by planar projection. In this work, we aim to extend sULM in 3D to image the whole organ and in order to perform an accurate characterization of the entire kidney structure. The extension of sULM into the 3D domain allows better localization and more robust tracking. The 3D metrics of velocity and pathway angular shift made glomerular mask possible. This approach facilitated the quantification of glomerular physiological parameter such as an interior traveled distance of approximately 7.5 ±0.6 microns within the glomerulus. This study introduces a technique that characterize the kidney physiology which can serve as a method to facilite pathology assessment. Furthermore, its potential for clinical relevance could serve as a bridge between research and practical application, leading to innovative diagnostics and improved patient care.

Sensitivity analysis of an inertial calibration method: Influence of leg position on 3D knee kinematics

BackgroundInertial systems are increasingly used to analyze human motion, especially for gait analyses and in clinical settings. Calibration methods for these systems are designed for ease of implementation, and previous studies have shown that they can provide accurate knee kinematics in the sagittal plane. However, the reason of their lack of accuracy in the other planes (i.e., transverse and frontal) remain unknown. Research questionThis study aimed to evaluate the sensitivity of one posture of a double-pose calibration method to analyse 3D knee kinematics during gait with two magnetic inertial measurement units (MIMU). This method consists of a standing posture and a posture with the leg stretched forward in the sagittal plane, which together define the sagittal plane. Our hypothesis was that a change in the definition of the sagittal plane during the calibration process was likely to affect the assessment of knee kinematics in the frontal and transverse planes. MethodsTen healthy participants wearing the KneeKG system and two MIMU completed the calibration process in five different leg positions (0°, 3°, 5°, 10° or 15° from the sagittal plane) for the second calibration posture. After static calibration, the participants walked on an instrumented treadmill at a speed of 1.1 m/s and 3D knee kinematics were calculated using the five different calibration conditions. ResultsMean absolute difference (MAD) between the swing-phase peak value of the curve corresponding to the leg in the sagittal plane (0° shift from this plane) when performing the second calibration posture and each of the other curves was 0.20–0.46° for knee flexion, 1.67–2.90° for adduction, and 0.72–1.46° for external rotation. MAD of the swing-phase peak value in the frontal plane was correlated (R2=0.81) with the angulation of the femur in the sagittal plane during calibration. SignificanceAn angular shift from the sagittal plane when performing a double-pose calibration method induces a minimal influence on the knee flexion/extension but larger influences on secondary knee motions.

High-frequency transverse acoustic interactions between two lean-premixed hydrogen combustors connected with cross-fire and cross-talk sections

Large-scale inter-combustor thermoacoustic interactions occur frequently in modern can-annular gas turbine combustion systems due to the presence of an annular cross-talk section upstream of the first stage turbine stator vanes. Although the whole system's modal dynamics depend on the relative dominance of low-frequency planar or high-frequency transverse acoustic waves, the majority of prior studies have chiefly focused on longitudinal mode instabilities. Motivated by the paucity of detailed information, here we examine high-frequency transverse acoustic interactions between two adjacent lean-premixed hydrogen combustors connected via two different pathways, known as cross-fire (XF) and cross-talk (XT) sections. We observe that the dual-combustor system undergoes high-frequency spinning mode in the clockwise direction, manifested as well-defined limit cycles with peak-to-peak amplitude of around 10 kPa. The transverse pressure oscillations, in contrast to the well-established low-frequency mutual synchronization dynamics, are not fully synchronized even in the presence of cross-talk communication. This situation leads to the formation of two closely-spaced 1T modes at 4.76 and 4.86 kHz in the respective hydrogen combustors, accompanied by the beating of the pressure fluctuations solely in the XF tube section. Remarkably, the pressure waves induced near the XF tube section tend to lag behind the pressure waves spinning in the injector face, demonstrating the existence of the angular shift characteristically connected to the high-frequency transverse combustion dynamics.

Quantifying the tangential oscillation of thermal stratification by using principal component analysis

Tangential oscillation of thermal stratification is a new finding in previous investigations on thermal-mixing process at pipeline T-junctions. This phenomenon can create regular temperature changes on the pipeline inner surface and lead to material damage caused by the degradation mechanism of thermal fatigue, which has been frequently reported as a reason for incidents in piping systems of nuclear power plants. Previous investigations cannot provide a quantitative description of this phenomenon, making it difficult to understand or evaluate the fatigue potential due to this phenomenon. In this study, a new method namely principal component analysis has been employed for quantitatively estimating the angular shift of the thermal stratification in pipe tangential direction. Time-dependent angular shift is extracted from the temperature data of the transient simulations of the pipe flow and confirms the initiation of the tangential oscillation of thermal stratification. Moreover, a characteristic frequency of approximately 2.3 Hz has been identified from the frequency spectrum of the time-dependent angular shift. It indicates a potential risk in the piping material due to thermal fatigue. Furthermore, results of this study show a high efficiency and accuracy of the principal component analysis method in quantifying tangential oscillation. It can be applied in further investigations of similar phenomena of thermal stratification.

Postural Risks in Dental Practice: An Assessment of Musculoskeletal Health.

In recent years, Romania's stomatology private practice sector has seen substantial growth, with many dentists fully committing to building and expanding their own practices, often funded by their personal income. This study aimed to explore how various postures affect the muscle groups of dentists (380), particularly focusing on identifying positions that may jeopardize their musculoskeletal health. A group of dentists effectively participated in this study (10), adhering to their regular work routines while wearing wearable sensors on their backs to monitor posture and activity. The data gathered from these sensors were analyzed using the RULA (rapid upper-limb assessment) and REBA (rapid entire-body assessment) tools. The findings indicated that the head and shoulder movements during dental procedures involved considerable and repetitive angular shifts, which could strain the neck and back muscles and heighten the risk of musculoskeletal problems. Additionally, the standing postures adopted by the dentists were associated with an increased risk of postural issues and greater overall fatigue. Extended periods of trunk and head tilting were also identified as contributing factors to posture-related challenges.

Corrected theory for transmitted Goos-Hänchen and Imbert-Fedorov shifts.

We analyze the role of the energy flow coefficient in beam shifts and develop the theory of the angle spectrum method to calculate the beam shifts of polarized beam reflection and transmission. By applying the self-consistency between the law of conservation of momentum and the angular Goos-Hänchen (GH) shift, we prove the necessity of the correcting energy flow coefficient of the transmitted light fields. For the air-glass interface, we find that the influence of the energy flow coefficient on the angular GH shift is very pronounced in the case of close grazing.

Aluminum doped non-stoichiometric titanium dioxide as a negative electrode material for lithium-ion battery: In-operando XRD analysis

Lithium-ion batteries (LIB) with titanium dioxide as anode material emerged as one of the most energy-storage systems. In this study, we investigate aluminum-doped non-stoichiometric titanium dioxide synthesized using sol-gel method and subsequent reduction treatment. Different analysis techniques, such as X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) tests are conducted for the analysis of material and performance of the battery. The XRD results affirmed that the sample consisted of pure titanium-dioxide phases with no other precipitated phases, such as aluminum oxide (α-Al2O3 or γ-Al2O3). XPS analysis evident that aluminum was successfully incorporated into the titanium-dioxide lattice and the presence of Ti3+ and oxygen vacancy signals confirmed its non-stoichiometric nature. TEM images implies that doping and its extent did not significantly affect the size and morphology of the nanoscale particles. The selected area electron diffraction shows that the sample consisted of a mixture of the anatase and rutile phases. The best-performing electrode was found to be the one composed of 1 % aluminum-doped non-stoichiometric titanium dioxide. After 200 charge-discharge cycles, the battery maintained a capacity of 195 mAh/g, retaining 97.5 % of its reversible capacity. Cyclic stability test under high current condition shows that the capacity remained at 157 mAh/g without any noticeable decay after 750 charge-discharge cycles at a 1 C rate. This material exhibited the lowest impedance and the highest lithium-ion diffusion rate. Additionally, in situ synchrotron-based XRD indicates coexistence of three phases such as a new reversible intermediate phase LiTiO2, a partially irreversible intermediate phase Li0.55TiO2, and the anatase phase. The analysis results indicated that the peak intensities and angular shifts were associated with the phase changes that occurred during charge and discharge of the electrochemical processes. The interaction mechanism study between lithium ions and the lattice of mixed phase (anatase, rutile) identified the occurrence of non-uniform stress resulting from lithium-ion insertion in the rutile phase, in addition to the irreversible reactions in both the rutile and anatase phases. Through the synergistic effect of heteroatom doping and oxygen vacancy treatment, the conductivity of titanium dioxide is enhanced, leading to improved performance in capacity, impedance, cycle life, and rate as an anode material in LIBs.

Ultrabright and stable top-emitting quantum-dot light-emitting diodes with negligible angular color shift

Top emission can enhance luminance, color purity, and panel-manufacturing compatibility for emissive displays. Still, top-emitting quantum-dot light-emitting diodes (QLEDs) suffer from poor stability, low light outcoupling, and non-negligible viewing-angle dependence because, for QLEDs with non-red emission, the electrically optimum device structure is incompatible with single-mode optical microcavity. Here, we demonstrate that by improving the way of determining reflection penetration depths and creating refractive-index-lowering processes, the issues faced by green QLEDs can be overcome. This leads to advanced device performance, including a luminance exceeding 1.6 million nits, a current efficiency of 204.2 cd A−1, and a T95 operational lifetime of 15,600 hours at 1000 nits. Meanwhile, our design does not compromise light outcoupling as it offers an external quantum efficiency of 29.2% without implementing light extraction methods. Lastly, an angular color shift of Δu’v’ = 0.0052 from 0° to 60° is achieved by narrowing the emission linewidth of quantum dots.

Cooper minima in high-Z atoms: effects of correlation and relativity on np photoionization

Photoionization dipole transition matrix elements pass through a zero or attain a minimum that leaves imprints on photoionization parameters like the cross-section, angular distribution asymmetry parameter, phase shift, and photoionization time delay. This minimum is commonly known as the ‘Cooper minimum’ (CM). The CM, in general, is strongly affected by relativistic and correlation effects. Previous works investigated CM in the 6p and 5p subshell photoionization up to Z = 100 using the single-particle Dirac-Slater (DS) method. The present work extends the earlier work to Z up to 120 using more accurate methods; Dirac–Hartree–Fock (DHF) which includes the relativistic effects and exchange correlations, and the relativistic random phase approximation (RRPA) which includes both initial and final state electron-electron correlations along with relativistic effects. In addition to the study of photoionization from the 6p and 5p subshells, the 4p subshell has also been investigated in the present work. To demonstrate the prominent effects in the high-Z atoms, Rn (Z = 86), Ra (Z = 88), No (Z = 102), Cn (Z = 112), Og (Z = 118), and Ubn (Z = 120) are investigated.

Parameter Extraction of Accelerated Moving Targets under Non-Quasi-Axial Incidence Conditions Based on Vortex Electromagnetic Wave Radar

Vortex electromagnetic wave radar carrying orbital angular momentum can compensate for the deficiency of planar electromagnetic wave radar in detecting motion parameters perpendicular to the direction of electromagnetic wave propagation, thus providing more information for target recognition, which has become a hot research field in recent years. However, existing research makes it difficult to obtain the acceleration and rotation centers of targets under non-quasi-axial incidence conditions of vortex electromagnetic waves. Based on this, this article proposes a variable speed motion target parameter extraction method that combines single element and total element echoes. This method can achieve three-dimensional information extraction of radar targets based on a uniform circular array (UCA). Firstly, we establish a non-quasi-axis detection echo model for variable-speed moving targets and extract echoes from different array elements. Then, a single element echo is used to extract the target’s range slow time profile and obtain the target’s rotation center z coordinate. We further utilize the target linear, angular Doppler frequency shift extremum, and median information to extract parameters such as target acceleration, tilt angle, rotation radius, and rotation center x and y coordinates. We analyzed the impact of different signal-to-noise ratios and motion states on parameter extraction. The simulation results have verified the effectiveness of the proposed algorithm.

Tunable spatial and angular spin splitting of reflected vortex-beam off hyperbolic metasurface

This paper investigated the spin splitting of the reflected beam with a vortex beam irradiating on a hyperbolic metasurface. This metasurface structure is the periodically rectangular-groove array on the surface of a hyperbolic crystal with the optical axis normal to its surface, where the array is a sub-wavelength biaxially hyperbolic grating with its periodical direction situated in the surface plane. Based on the hexagonal nitride boron crystal, we theoretically and numerically analyzed the spatial and angular spin splittings of the reflected beam, containing those produced by the transverse and longitudinal shifts. We found that the spatial shifts or spin splitting can be obtained in the first-order approximation of beam deflection, but the angular shifts can be described in the second-order approximation so that it enormously varies with the beam waist. Due to the hyperbolic anisotropy of the metasurface and the intrinsic orbital angular momentum in the incident beam, the expressions of spatial and angular shifts are effectively modified, and a unique double reflection effect occurs on the surface. Near certain reflective intensity distribution singularities, extremely asymmetrical spin splitting can be observed. These shifts and spin splitting can be tuned by varying the orientation of the incident plane and the angle of incidence.

The competition between charge density wave and superconductivity in the kagome metal CsV3(Sb1-xPbx)5 single crystals

Kagome metal AV3Sb5 (A = K, Rb, Cs) has garnered considerable attention for its abundant exotic quantum phenomena and the special competitive relationship between charge density wave (CDW) and superconductivity (SC). In this work we explore the unconventional coupling between charge density wave and superconductivity by means of the substitutional doping of Pb atoms with Sb atoms. Microscopic characterization and performance tests provide valuable phase diagram information for CsV3(Sb1-xPbx)5. Upon Pb doping, a pronounced competition between the charge density wave transition temperature TCDW and the superconducting temperature Tc was observed. Analysis of changes in Debye temperature ΘD and lattice constant, it is shown that Pb doping affects atomic bonding and may strengthen the coupling between adjacent kagome layers to some extent. Furthermore, the small angular shift of the diffraction peak and increased full width at half maximum (FWHM) indicate that the doping causes crystal defects and distorts the crystal structure, which will change the charge density in the local area and may affect the superconductivity. This result further reveals a close correlation between the superconductivity of the system and the electronic structure of the kagome plane in the CsV3Sb5 system. Overall, our results suggest that the observed competition arises from the complex interplay of multiple factors.

Shift of Brewster's angle with two-dimensional materials and structures

The Brewster effect has a number of applications in antireflection coatings, spectroscopy, and polarization optics, but its tunability is still of high demand. In this Letter, we discover a method of Brewster angle control with two-dimensional conducting layers. Namely, we analyze the angular shift of Brewster's angle depending on the surface conductivity of a two-dimensional layer. First, we derive the analytical model with exact conductivity-dependent solution. Then, we investigate the Brewster angle shift in the cases of monolayer graphene and plasmonic metasurface. Finally, we support our analytical results by the full-wave numerical simulations. The results obtained may find a plethora of applications in flat optical and planar photonic devices. Published by the American Physical Society 2024

Conditional convolutional GAN-based adaptive demodulator for OAM-SK-FSO communication.

The perturbation of atmosphere turbulence is a significant challenge in orbital angular momentum shift keying-based free space optical communication (OAM-SK-FSO). In this study, we propose an adaptive optical demodulation system based on deep learning techniques. A conditional convolutional GAN (ccGAN) network is applied to recover the distorted intensity pattern and assign it to its specified class. Compared to existing methods based on convolutional neural networks (CNNs), our network demonstrates powerful capability in recovering the distorted light beam, resulting in a higher recognition accuracy rate under the same conditions. The average recognition accuracy rates are 0.9928, 0.9795 and 0.9490 when the atmospheric refractive index structure constant $C_n^2$ is set at 3 × 10-13, 4.45 × 10-13, 6 × 10-13m-2/3, respectively. The ccGAN network provides a promising potential tool for free space optical communication.

Measurement of the surface susceptibility of single-layer atomic crystal by the photonic spin Hall effect in momentum space

Fast and robust measurement of the surface susceptibility is still in urgent need for investigation and application of atomically thin crystals. In this work, we propose an effective method to measure the surface susceptibility of single-layer graphene by detecting the photonic spin Hall effect in momentum space. At a graphene interface, the beam separations with different spin states contain an angular component due to the existence of surface susceptibility. By implementing a postselection with real weak value in our scheme, the contribution of the spatial spin-Hall shift is excluded and the angular one is amplified for detection. It is demonstrated that treating the angular shift as a pointer allows for a reliable determination of the surface susceptibility. Our method may pave a way for the optical parameter characterization of two-dimensional atomic crystals via angular metrology.

Enhancing Triangulation of Interplanetary Type III Bursts through Wavevector Correction

Interplanetary Type III bursts, generated by relativistic electron beams at solar flare reconnection sites, are explored through an investigation of 152 instances observed by the Solar Terrestrial Relations Observatory mission. This study reveals that the absolute values of the wavevector deviations from the Sun–spacecraft line are statistically 3.72 and 2.10 larger than predicted by the density model, assuming fundamental and harmonic emission, respectively. Through Monte Carlo simulations, we examine the impact of scattering by density inhomogeneities on the apparent locations of radio emissions in the interplanetary medium. The findings indicate that relative density fluctuations of 0.40 can account for the observed angular shift, a conclusion supported by the multiple flux-tube solar wind model, which confirms the presence of such magnitude of relative perpendicular density fluctuations in the solar wind. We propose a wavevector correction that incorporates this effect to enhance the triangulation of interplanetary Type III bursts, demonstrating that radio triangulation, with this correction, can reliably track electron beams in the interplanetary medium.

Enhancing light extraction efficiency and color stability for OLED by truncated micro-cone array films

A newly truncated micro-cone array film as light extraction layer for organic light emitting diodes (OLEDs) has been developed, which was fabricated by process combined with photolithography, polydimethylsiloxane (PDMS) molding, self-assembled anti-adhesion, and ultraviolet (UV) forming techniques. In this study, by varying the sidewall angle and fill factor of this film, their influences on the optical properties and light extraction efficiency for OLED are fully investigated. As a result, device performance of OLED employed truncated micro-cone array film, with a high fill factor and sidewall angle of 76.49⁰, was found to be significantly enhanced up to 52% compared with the reference OLED. Notably, the proposed truncated micro-cone array film also stabilized emissive color stability while the viewing angle changes from 0° to 70°, achieving an excellent angular shift with CIE-indices of (0.0025, 0.0066). Aforementioned findings contribute to the development in advanced OLEDs for display and lighting applications.

Response of personal dosemeters on various age-specific anthropometric phantoms under external irradiation applied to areas affected by the 2011 Fukushima Daiichi nuclear accident.

We experimentally obtained the responses of two personal dosemeters (PDs, D-shuttle and Dose-i) attached on five age-specific phantoms under rotational irradiation geometry, which simulated an environment that was radiologically affected by the 2011 Fukushima nuclear accident using of a 137Cs source. Although the PD responses showed an angular phase shift by the PD position on the phantoms, the angular dependence was small when the contamination was widely distributed. The PD responses decreased as much as ~10% with the increase in the phantoms' body size. Although there were ~17% variations in the PD/ADE (ambient dose equivalent) ratio depending on the different PDs, this variation was due to the fact that D-shuttle was calibrated with the inclusion of a safety margin. The PD/ADE ratios were similar to the effective dose to ADE ratios for corresponding age-specific phantoms. Our results suggest that these two PDs can provide reasonable estimates for age-dependent effective doses.

Impact of the Galactic bar on tidal streams within the Galactic disc

Tidal streams of disrupted clusters are powerful probes of the gravitational potential of the Galaxy and they are routinely detected in the stellar halo of the Milky Way. It was recently shown that tidal streams of open clusters can now also be detected within the Milky Way disc. In this work, we highlight the fact that disc tidal streams also provide a powerful new diagnostic of the non-axisymmetric disc potential and may, in principle, provide a new constraint on the pattern speed of the Galactic bar. In particular, we show how the stream-orbit misalignment for an open cluster on a quasi-circular disk orbit in the solar vicinity varies as a function of the position with respect to the bar resonances. The angular shift rises beyond corotation, reaching values as high as 30° close to the outer Lindblad resonance (OLR), then dropping again and reversing its sign beyond the OLR. We applied this mechanism to the recently detected tidal stream of the Hyades open cluster and we note that the detected stream stars would be very similar when taking a potential a priori with no bar or with a fast pattern speed of 55 km s−1 kpc−1 (or lower than 30 km s−1 kpc−1). However, we find that candidate stream stars are different than previously detected ones when adopting a potential with a bar pattern speed of 39 km s−1 kpc−1, which is consistent with the most recent determinations of the actual Galactic bar pattern speed. Previously detected Hyades candidate members would, on the other hand, favour a barless galaxy or a fast bar of pattern speed 55 km s−1 kpc−1. Interestingly, the previously reported asymmetry in star counts within the leading and trailing tails of the Hyades tidal stream persists in all cases. Our study conclusively demonstrates that the effect of disc non-axisymmetries cannot be neglected when searching for tidal streams of open clusters and that current candidate members of the Hyades stream should not be trusted beyond a distance of 200 pc from the cluster. Moreover, our study allows for ideal targets to be provided for high-resolution spectroscopy follow-ups, which will enable conclusive identifications of the Hyades stream track and provide novel independent constraints on the bar pattern speed in the Milky Way.