Angle Resolution Research Articles

Quantization error for weak RF simultaneous signal estimation

In a congested signal environment, it is difficult to obtain estimates of weak RF signal parameters. Determining signal parameter estimates in real time is a challenge for electronic warfare receivers that aim to receive multiple simultaneous signals. Prior work provided estimates of weak signal parameters (weak signal frequency and weak signal amplitude) without taking into account any error introduced by analog-to-digital converters that are inherently part of digital signal processing systems. In order to obtain realistic estimates, we need to take error introduced by an ADC into account. The primary aim of this paper is to quantify error introduced by a single ideal ADC as a function of angle. This paper presents a method to estimate angle resolution and quantization levels in N-bit analog-to-digital converters (ADCs) for use in a weak radiofrequency (RF) simultaneous signal estimation process. The paper quantifies the error in the angle quantization of an N-bit ADC for an input complex signal that is the instantaneous frequency obtained for the situation in which there are two simultaneous signals (with one strong signal and one weak signal) in a weak RF simultaneous signal estimation process. The presented method describes the process to determine the angle quantization range, angle quantization uncertainty, and angle quantization error. This approach has potential applications in electronic warfare (EW) systems. The approach also has potential for assessing ADC performance for measurements that approach the quantum limit. Results are presented for 1-bit, 2-bit, 3-bit, and 10-bit ADCs.

A Novel 3D ArcSAR Sensing System Applied to Unmanned Ground Vehicles

Microwave radar has advantages in detection accuracy and robustness, and it is an area of active research in unmanned ground vehicles. However, the existing conventional automotive corner radar, which employs real-aperture antenna arrays, has limitations in terms of observable angle and azimuthal resolution. This paper proposes a novel 3D ArcSAR method to address this issue, which combines rotational synthetic aperture radar (SAR) and direction estimation algorithms. The method aims to reconstruct 3D images of 360° scenes and offers distinctive advantages in both azimuthal and altitudinal sensing. Nevertheless, due to the unique structural characteristics of vehicle SAR, it is limited to receiving only a single snapshot signal for 3D sensing. We propose a resolution algorithm based on ArcSAR and the iterative adaptive approach (IAA) to resolve the limitation. Furthermore, the errors in altitude angle estimation of the proposed algorithm and conventional algorithms are analyzed under various conditions, including different target spacing and signal-to-noise ratio (SNR). Finally, we design and implement a prototype of the 3D ArcSAR sensing system, which utilizes a millimeter-wave MIMO radar system and a rotating scanning mechanical system. The experimental results obtained from this prototype effectively validate the effectiveness of the proposed method.

Multi-Scale Feature Residual Feedback Network for Super-Resolution Reconstruction of the Vertical Structure of the Radar Echo

The vertical structure of radar echo is crucial for understanding complex microphysical processes of clouds and precipitation, and for providing essential data support for the study of low-level wind shear and turbulence formation, evolution, and dissipation. Therefore, finding methods to improve the vertical data resolution of the existing radar network is crucial. Existing algorithms for improving image resolution usually focus on increasing the width and height of images. However, improving the vertical data resolution of weather radar requires a focus on improving the elevation angle resolution while maintaining distance resolution. To address this challenge, we propose a network for super-resolution reconstruction of weather radar echo vertical structures. The network is based on a multi-scale residual feedback network (MR-FBN) and uses new multi-scale feature residual blocks (MSRB) to effectively extract and utilize data features at different scales. The feedback network gradually generates the final high-resolution vertical structure data. In addition, we propose an elevation upsampling layer (EUL) specifically for this task, replacing the traditional image subpixel convolution layer. Experimental results show that the proposed method can effectively improve the elevation angle resolution of weather radar echo vertical structure data, providing valuable help for atmospheric detection.

ORCNN-X: Attention-Driven Multiscale Network for Detecting Small Objects in Complex Aerial Scenes

Currently, object detection on remote sensing images has drawn significant attention due to its extensive applications, including environmental monitoring, urban planning, and disaster assessment. However, detecting objects in the aerial images captured by remote sensors presents unique challenges compared to natural images, such as low resolution, complex backgrounds, and variations in scale and angle. Prior object detection algorithms are limited in their ability to identify oriented small objects, especially in aerial images where small objects are usually obscured by background noise. To address the above limitations, a novel framework (ORCNN-X) was proposed for oriented small object detection in remote sensing images by improving the Oriented RCNN. The framework adopts a multiscale feature extraction network (ResNeSt+) with a dynamic attention module (DCSA) and an effective feature fusion mechanism (W-PAFPN) to enhance the model’s perception ability and handle variations in scale and angle. The proposed framework is evaluated based on two public benchmark datasets, DOTA and HRSC2016. The experiments demonstrate its state-of-the-art performance in aspects of detection accuracy and speed. The presented model can also represent more objective spatial location information according to the feature visualization maps. Specifically, our model outperforms the baseline model by 1.43% mAP50 and 1.37% mAP12 on DOTA and HRSC2016 datasets, respectively.

P-315 To study the efficacy of Transvaginal ultrasound-guided Embryo Transfer over Transabdominal ultrasound-guided Embryo Transfer in transfers with poor visibility due to obesity or marked retroversion

Abstract Study question Why is Transvaginal guided embryo transfer,understudied and underutilised in difficult cases of embryo transfers with compromised visibility of uterine canal in Transabdominal ultrasound ? Summary answer In patients with poor visibility of uterine canal using TAUS due Obesity, retroveted uterus,PID,pelvic adhesions, endometriosis, TVUS-ET gives significantly higher clinical Pregnancy rates. What is known already TAUS-ET is most popular method of Embryo transfer worldwide. Despite the benefits , this procedure also presents some important drawbacks. Firstly, TAUS-guided ET requires an assistant to operate the transducer while physician performs ET procedure. Moreover, patient needs to fill her urinary bladder to enable visualization of uterine canal, which causes discomfort and sometimes uterine cramping during ET, which in turn can negatively impact implantation rates.TVUS is the main technique used in all other gynecological investigations. Because of high frequency and close proximity to target area, TVUS transducers provide better resolution of the uterocervical angle and improved overall image quality. Study design, size, duration This retrospective study was conducted to compare efficacy of TVUS-guided ET to conventional TAUS-guided ET in difficult transfers, who underwent treatment at Triveni IVF, Darbhanga, India between November 2020 to December 2022. It was based on data extracted from records of all women who underwent difficult TAUS-ET procedure between Nov 2020 to Nov 2021.Data from records of matching number of women who underwent TVUS-ET procedure between Dec 2021 to Dec 2022 were used for comparison. Participants/materials, setting, methods All were ICSI and FET transfers. Inclusion criteria: (1) All included between 25–35 years of age with difficult visualisation of uterine canal during TAUS-Mock ET in previous cycle (2) BMI ≥ 30; (3) Retroverted uterus due to any underlying pathology 4)All pts included had good ovarian reserve; (4) unexplained infertility >3 years. Exclusion criteria: (1) severe male factor infertility, (2) any intrauterine factor of infertility (3) ovarian endometrioma or PCOS and (5) multiple ICSI failure (>3 trials). Main results and the role of chance Total of 123 cycles,61 guided by TVUS (Group 1) and 62 TAUS (Group 2) were included. Our results showed significantly higher Clinical Pregnancy rate in TVUS group as compared to TAUS group, in difficult transfers (43.3% vs. 36.1 % p = 0.0045). VAS (visual analog scale) of the pain during ET was significantly less in TVUS group in comparison to TAUS group (17% vs 64% p = 0.0001), also the abdominal discomfort was significantly less in TVUS group in comparison to TAUS group (11% vs. 69 % p = 0.0001). TVUS-ET group showed significantly higher CPR as it has better resolution due to proximity to target organs allowing proper visualization of catheter tip especially in cases with obesity and marked uterine retroversion.TVUS has superior role in cases with difficult transfer because it can easily analyze the cause of difficult transfers as endocervical crypts, marked anteverted uterus, cervical canal tortuosity. Another advantage of TVUS is requiring emptied urinary bladder in contrast to TAUS. Full bladder is both time consuming and causes abdominal discomfort and uterine cramps leading to increased patient anxiety.As regards to abdominal discomfort and uterine cramps, there was extremely high statistical significance between the two groups in our study. Limitations, reasons for caution Despite the wide benefits,TVUS-ET has not been widely adopted, on account of difficulty in manipulating ET catheter and vaginal transducer simultaneously in very constricted area.Other comfortable approaches that may assist physicians such as inner catheter can be pushed by embryologist while physician holds TVS-probe and outer catheter in place. Wider implications of the findings The results suggested that TVUS-guided ET was better in difficult transfers with poor visibility of uterine canal in studied sample. This technique presented deserves consideration for wider use since it can offer better visualization, excellent comfort to patients during the procedure, and requires only one operator. Trial registration number Not applicable

Viewing angle enhancement for integral imaging display using two overlapped panels.

Integral imaging three-dimensional (3D) display relies on display panel to provide visual information, but the intrinsic trade-off between the wide viewing angle and high resolution refrains its application in high-throughput 3D display. We propose a method to enhance the viewing angle without sacrificing the resolution by using two overlapped panels. The additionally introduced display panel is composed of two parts: the information area and the transparent area. The transparent area loaded with blank information enables light passing through without any modulation, while the opaque information area is loaded with element image array (EIA) for 3D display. The configuration of the introduced panel can block crosstalk from the original 3D display and establish a new and viewable perspective. Experimental results show that the horizontal viewing angle can be effectively extended from 8° to 16°, demonstrating the feasibility and effectiveness of our proposed method. This method provides the 3D display system with a higher space-bandwidth product, making it a potential technique to be applied for high information-capacity display, including integral imaging and holography.

Filter-Bank-Enabled Leaky-Wave Antenna Array Technique for Full-Band-Locked Radar System in Stitched Frequency-Space Domain

Inspired by the filter-bank (FB) concept that is normally used for multi-rate signal processing, an FB-enabled array technique of leaky-wave antennas (LWAs) is proposed and studied for creating full-band-locked frequency-scanning radar (FSR) systems in a stitched frequency-space domain. This is mainly for addressing the coupling dilemma between the range and angle resolutions, which is historically and naturally inherited from a conventional FSR. Firstly, the typical frequency-modulated continuous-wave system architecture is selected to exemplify and recall the characteristics of a conventional FSR with emphasis on its resolution coupling. Then, a radar solution featuring a stitched frequency-space domain and depending on an FB-enabled array of LWA channels is introduced for realizing the desired resolution decoupling. With the radar equation, FB-related conditions for obtaining the critical “frequency-space stitching” are analytically derived and converted into relevant design specifications of an LWA array, including engineered beam-scanning functions, beam-crossovers, and phase alignments. To facilitate the practical implementation of such a front-end array technique, a detailed and generalized design flow is developed. Finally, for a simple proof of concept, an FB-enabled two-channel LWA array is modeled, fabricated, and measured. Simulated and measured results are in reasonable agreement; both demonstrate the desired “frequency-space stitching” behavior, i.e., enhanced spectrum bandwidth and widened radiation beamwidth. The proposed array solution may be potentially deployed for FSR systems with a full-band-locked beam illumination and a decoupled range-angle resolution, which may present a highly competing scheme against the phased array radar techniques.

Microfiber optomechanical torsion sensor

In this paper, we propose and demonstrate experimentally an optomechanical torsion sensor using a microfiber mechanical resonator. The torsion angle could be obtained by monitoring the resonant frequency shifts of the microfiber resonator. Theoretical and experimental results show that the shift of resonant frequency is non-linear to the torsion angle, and the fundamental mode is more sensitive than other higher modes. The highest sensitivity of the sensor tested in our experiments is 1,687 Hz/degree, and the corresponding resolution of torsion angle is up to 0.0006°, which is 2 orders of magnitude higher than that of the reported fiber-optic torsion sensors. The proposed sensor is a promising candidate for the practical engineering applications.

Multi-parameter e-skin based on biomimetic mechanoreceptors and stress field sensing

Tactile sensing has been a key challenge in robotic haptics. Inspired by how human skin sense the stress field with layered structure and distributed mechanoreceptors, we herein propose a design for modular multi-parameter perception electronic skin. With the stress field sensing concept, complex tactile signals can be transformed into field information. By analyzing the stress field, the real-time three-dimensional forces can be resolved with 1.8° polar angle resolution and 3.5° azimuthal angle resolution (achieved up to 71 folds of improvement in spatial resolution), we can also detect the hardness of object in contact with the electronic skin. Moreover, we demonstrate random assembly of the sensing arrays and integration of our electronic skin onto differently curved surfaces do not lead to any measurement variation of the stress field. This result reveals that the sensing elements in our electronic skin system can be modularly made and exchanged for specific applications.

A resonant inertial impact rotary piezoelectric motor based on a self-clamping structure

A resonant inertial impact rotary piezoelectric motor based on a self-clamping structure is designed, assembled, and tested. The designed piezoelectric motor mainly includes a rotor (two vibrators, preload mechanism, and intermediate connection mechanism), a clamping mechanism, and another auxiliary mechanism. The piezoelectric ceramic sheet on the rotor drives the vibrator to swing under the excitation of a single harmonic wave. Because there is a clamping mechanism formed by the combination of clamp baffle and fixed clamp ring, thus the half-cycle resonant rotation of the rotor can be effectively completed, and repeated harmonic excitation can realize the unidirectional continuous rotation and swing of the rotor. The whole excitation process of the motor is in a resonance state, which has significant advantages, such as low friction and simple structure, compared with the traditional quasi-static piezoelectric motor. The structure of the piezoelectric motor is designed and analyzed using COMSOL5.5 software and then the motor performance is tested and analyzed by building an experimental platform to verify the feasibility of the motor design. The final experimental results show that the optimal working frequency of the piezoelectric motor is 150 Hz, which is consistent with the characteristic frequency of the simulation. When the motor prototype is under the conditions of optimal operating frequency 150 Hz, voltage 240 Vp-p, and preload torque 7.8 N.mm, the maximum angular speed can reach 2.4 rad/s, the maximum load can reach 27.8 N mm and the maximum resolution of the movement angle can reach 0.941°.

Nested Closed-Loop Control of Quasi-Static MEMS Scanners With Large Dynamic Range

This research discusses the challenges in implementing a fully electrical closed-loop control system for high-end applications of quasi-static microscanners, accounting at the same time for wide aperture, high-accuracy and wide-bandwidth. The discussion highlights how not only the ringing of the main mode, but also the presence of spurious modes and nonlinearity, impact the closed loop stability and accuracy. A novel control approach based on nested loops is conceived and implemented in the digital domain in a mixed-signal application-specific integrated circuit (ASIC). The developed versatile ASIC is designed to be coupled to different types of micromirrors, with fundamental frequency ranging from few hundred Hz to few kHz, by simply adjusting coefficients in the digital domain. The ASIC is here successfully operated with two micromirrors and results demonstrate saw-tooth position control at 28-32 deg field of view and up to 120 Hz refresh rate, while holding at the same time a tilt angle resolution of 25 mdeg r.m.s. (dynamic range of 60 dB) and a linearity error below 1%

A high-resolution and high-efficiency x-ray spectrometer based on a multi-cone crystal

A curved x-ray spectrometer based on a multi-cone crystal has been developed and demonstrated to improve the spectra resolution and intensity efficiency measurements by our experiments and simulations. Here 6000 conical rings with a single-ring of 10 μm to free the stress on the lattice planes was successfully realized in the multi-cone crystal, which provides a much larger solid collection angle and higher resolution than the usually-used planer crystal in the general x-ray spectrometer. Thus, the experimental results show that its spectrum resolution can reach ∼3.5 eV (full-width half maximum) with the corresponding of 1420 (∼4976 eV). The intensity at the focus spot can be 110 times higher compared to that measured by a planer crystal spectrometer. Meanwhile, these results have also been confirmed by our numerical studies with our new developed x-ray arbitrary-surface-crystal diffraction software, X-chase. Attentional development on the x-ray spectrometer is of specific importance in the high energy density physics, inertial confinement fusion, and Astrophysics experiments.

Self-powered angle-resolved triboelectric nanogenerator for underwater vibration localization

Precise locating in underwater environment is essential for marine engineering and national security. However, the current technologies usually suffer from energy and complexity issues. Here, a self-powered angle-resolved triboelectric nanogenerator (AR-TENG) is proposed for underwater vibration detecting and locating in a simple and energy-effective fashion. The AR-TENG is made of metal balls and an inverted conical unit consisting of fluorinated ethylene propylene film and multiple sector-like electrodes, where each electrode corresponding to one sensing channel. Each channel of AR-TENG can respond to low-frequency variations with linear electrical outputs and a maximum power density of 1.28 μW·cm−2 at a load resistance of 200 MΩ. Most importantly, the output voltage ratio of two adjacent channels is only related to the vibration direction, endowing AR-TENG with the capability of vibration direction recognition with an angle resolution of 15°. As a result, the underwater vibration locating can be realized by simply intersecting the vibration directions respectively determined by two AR-TENGs arranged in parallel, performing a locating accuracy of >95 %, assisted with a simple trigonometric function and geometric relation. This new scheme is simple, effective and energy-autonomous, holding great potential for various underwater applications.

An Algorithm to Correct the Sensitivity Distribution of a Retarding Field Analyzer for Photoelectron Holography

Recently, we developed a retarding field analyzer (RFA) with high energy resolution and wide acceptance angles, which was installed at BL25SU in SPring-8, Japan. This apparatus enables us to measure photoelectron angular distributions (photoelectron holograms) with a solid angle of ±49° in a few minutes, and this approach is now being applied to measure the atomic arrangements of dopants and interfaces. However, correcting the sensitivity distribution of the measured images by the RFA is important in processing this data. The sensitivity distribution of the RFA is difficult to measure directly because it depends on the geometry of a sample, the kinetic energy of the photoelectrons, and so forth. Therefore, we developed an image processing algorithm to estimate the sensitivity distribution using spherical harmonics. This approach is more accurate than a Fourier transform and can efficiently correct the sensitivity distribution. Moreover, the algorithm can also be adopted in a wide variety of other applications in addition to RFA measurements.

Multiview synthetic aperture radar target recognition method using joint sparse representation and random weight matrix

Multiview synthetic aperture radar (SAR) images could provide richer information for target recognition as reported in previous works. This study exploits multiview SAR images with application to target recognition via the combination of joint sparse representation (JSR) and random weight matrix. First, the multiview SAR images are clustered into several view sets via a coarse clustering algorithm. In this way, the views in each set tend to share high correlations so they can be properly represented with JSR. For the reconstruction errors from different views, they are fused through a random weight matrix, which includes a rich set of linear weight vectors. Afterwards, the fused errors at different choices of weight vectors are analyzed to form a decision value for target recognition, which could better reflect the differences between different classes through multiview SAR images in comparison with traditional JSR-based methods. Therefore, the overall SAR target recognition performance can be effectively enhanced. Experiments are investigated on the moving and stationary target acquisition and recognition dataset under several operating conditions. The results reveal the high effectiveness of the proposed method under standard operating condition and good robustness under typical extended operating conditions including depression angle variance, configuration variants, noise corruption, partial occlusion, and resolution variance.

Design of a circum-scanning light detection and ranging emission system

The need for imaging and detecting in various instrument areas has brought light detection and ranging (LiDAR) to the forefront of consumer technology. Among different LiDAR, microelectromechanical system (MEMS) LiDAR has more appeal due to its small size and high integration. However, due to its low resolution and slight scanning angle, MEMS LiDAR does not apply to all scenes. Thus we presented a 360-deg scanning LiDAR emission optical system. Design formulas were deduced from theoretical formulas. In this system, the aspheric lens collimated the beam, MEMS micromirrors tracked the concentric circular beams, and the converging lens compensated for the divergence of the outgoing beam. By doing so, the target was scanned 360 deg at high resolution. With Zemax, the fast-axis divergence angle was 0.2484 mrad, the slow-axis divergence angle was 0.1546 mrad, and the system energy utilization rate was 84.16% with an angular resolution of 0.0142 deg at a distance of 10,000 mm. We have provided a potential solution for improving the scanning angle and resolution of MEMS LiDAR.

Twelve-month outcomes of single-step transepithelial photorefractive keratectomy for moderate hyperopia and hyperopic astigmatism

BackgroundConventional mechanical or alcohol-assisted photorefractive keratectomy (PRK) techniques for correction of hyperopia and hyperopic astigmatism were associated with inconsistent results. The aim of this study is to evaluate the 12-month visual and refractive outcomes of the relatively new single-step transepithelial photorefractive keratectomy (TE-PRK) for moderate hyperopia and hyperopic astigmatism. MethodsThis is a prospective interventional study. Forty-eight eyes of 30 patients with moderate hyperopia or hyperopic astigmatism with a cycloplegic spherical equivalent refraction (SEQ) between 2.0 and 4.5 diopters (D) underwent single-step StreamLight® TE-PRK using EX500 excimer laser (Alcon Laboratories, USA). The main outcome measures were recorded at 6 and 12 months postoperatively including assessment of logarithm of the minimum angle resolution (logMAR) uncorrected and corrected distance visual acuity (UDVA, CDVA), cycloplegic refraction, corneal topographic changes as well as post-PRK peripheral haze grading.ResultsThe mean preoperative cycloplegic SEQ was significantly reduced from 3.21 ± 0.61 D to 0.35 ± 0.04 D and 0.41 ± 0.04 D at 6 and 12 months, respectively (P < 0.001). The mean preoperative UDVA significantly improved from 0.53 ± 0.02 logMAR to 0.07 ± 0.01 logMAR and 0.08 ± 0.01 logMAR at 6 and 12 months, respectively (P < 0.001) while the mean preoperative logMAR CDVA showed non-significant change over time throughout the study (P = 0.135). At the end of the study, 41 eyes (85.4%) achieved UDVA of 20/25 or better and no eye lost any lines of CDVA. Thirty-eight eyes (79.1%) had a postoperative cycloplegic cylinder of 0.5 D or less at 12 months. The mean preoperative mean keratometry showed significant increase at 6 and 12 months postoperatively (P < 0.001) while there was no significant change between the two postoperative visits denoting topographic stability (P = 0.058). The mean postoperative Q value at 6 and 12 months showed a significant prolate shift (P < 0.001). No haze was observed in 62.5% and 85.4% of the enrolled eyes at 6 and 12 months, respectively.ConclusionsSingle-step StreamLight® TE-PRK for moderate hyperopia and hyperopic astigmatism achieved acceptable visual and refractive outcomes.Trial registration: (Clinicaltrials.gov): NCT05261685, 2 March 2022, retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT05261685

Algebraic Methods for Achieving Super-Resolution by Digital Antenna Arrays

The actual modern problem of developing and improving measurement and observation systems (including robotic ones) is to increase the volume and quality of the information received. Increasing the angle resolution to values significantly exceeding the Rayleigh criterion, i.e. achieving super-resolution is one of important ways to solve the problem. Angular super-resolution which makes it possible to detail images of research objects and their individual fragments, improves the quality of solutions to detection, recognition and identification problems, increases the range of such systems. In many papers methods developed by authors to achieve a super-resolution based on approximate solutions of inverse problems in the form of Fredholm integral equation of the first kind of convolution type called algebraic are presented. The methods used, as well as their varieties, make it possible to reduce solutions of inverse problems posed to solving sets of linear algebraic equations (SLAE). This paper presents results of further improvement of algebraic methods based on intelligent analysis of received signals. It is shown that their use in systems based on digital antenna arrays makes it possible to increase the achieved degree of exceeding the Rayleigh criterion. In the course of numerical experiments with a mathematical model, the stability of the solutions obtained and their adequacy were confirmed. The numerical results obtained open the following possibilities: (1) obtaining images of studied objects with a resolution exceeding the Rayleigh criterion by 4 to 10 times, (2) determining the angular coordinates of individual small-sized objects as part of multi-element complex objects (group targets), (3) clarifying boundaries of extended objects and their individual elements, (4) localizing individual bright objects on a smoothly inhomogeneous reflective background. Applying presented new methods does not require a significant computing power, what allows you to work in a real time mode using relatively simple and inexpensive computing devices. The ways of further improvement of presented algebraic methods for solving applied inverse problems are described.

Long-term Clinical Outcome of Refractive Corneal Inlays for Compensation of Presbyopia

Purpose: To study the long-term efficacy and safety of Flexivue Microlens refractive corneal inlays in Koreans for compensation of presbyopia.Methods: Flexivue Microlens inlays were implanted in nine eyes at Samsung Medical Center from October 2015 to February 2018. The follow-up period was 1.95 ± 0.6 years. Pre- and postoperative near/intermediate/distant visual acuity, spherical equivalent, contrast sensitivity, defocus curve, keratometry, and patient satisfaction were evaluated retrospectively.Results: The uncorrected near visual acuity (UNVA) of the operated eye increased significantly to 0.27 ± 0.10 logarithm of the minimal angle resolution (logMAR) after 6 months (p = 0.012). At the last observation, it was 0.32 ± 0.21 logMAR, which improved compared to before surgery, but the difference was not significant (p = 0.127). The binocular UNVA improved significantly to 0.19 ± 0.78 logMAR at 6 months postoperatively (p = 0.017) and to 0.21 ± 0.13 logMAR at the last observation (p = 0.028). There was no difference in the binocular uncorrected distant visual acuity (UDVA) before and after surgery, but the UDVA of the operated eye decreased significantly to 0.38 ± 0.15 logMAR at 6 months postoperatively (p = 0.007) and to 0.32 ± 0.21 logMAR at the last observation (p = 0.012). Satisfaction with near vision improved significantly after surgery; 14.3% of the patients had a score of 4 (good) or higher and 42.9% did not require near-vision glasses. In one case, the inlay was removed after 17 months due to blurred vision.Conclusions: The Flexivue Microlens has a low risk of complications and is a reversible technique. However, the near vision improvement was temporary and distance vision deteriorated. In addition, the Koreans examined had relatively low satisfaction and high spectacle dependence.

Active galactic nuclei jets simulated with smoothed particle hydrodynamics

ABSTRACTSimulations of active galactic nuclei (AGN) jets have thus far been performed almost exclusively using grid-based codes. We present the first results from hydrodynamical tests of AGN jets, and their interaction with the intracluster medium (ICM), using smoothed particle hydrodynamics as implemented in the swift code. We launch these jets into a constant-density ICM, as well as ones with a power-law density profile. We also vary the jet power, velocity, opening angle, and numerical resolution. In all cases we find broad agreement between our jets and theoretical predictions for the lengths of the jets and the lobes they inflate, as well as the radii of the lobes. The jets first evolve ballistically, and then transition to a self-similar phase, during which the lobes expand in a self-similar fashion (keeping a constant shape). In this phase the kinetic and thermal energies in the lobes and in the shocked ICM are constant fractions of the total injected energy. In our standard simulation, two thirds of the initially injected energy is transferred to the ICM by the time the jets are turned off, mainly through a bow shock. Of that, $70{{\%}}$ is in kinetic form, indicating that the bow shock does not fully and efficiently thermalize while the jet is active. At resolutions typical of large cosmological simulations (mgas ≈ 107 M⊙), the shape of the lobes is close to self-similar predictions to an accuracy of $15{{\%}}$. This indicates that the basic physics of jet-inflated lobes can be correctly simulated even at such resolutions (≈500 particles per jet).