Performance evaluation of ground layer adaptive optics based on layer correction efficiency.

Ground layer adaptive optics (GLAO) has been widely employed in wide-field observations with ground-based telescopes. However, the present evaluation of GLAO performance lacks a criterion in terms of turbulence layer correction. This deficiency results in a significant gap in understanding the effectiveness of GLAO correction at different heights of the turbulence layer, thereby hindering the optimization of GLAO system performance. To bridge this gap, this Letter introduces a new, to the best of our knowledge, performance criterion for GLAO, termed layer correction efficiency (LCE). This criterion is formulated to quantify the effective compensation of the GLAO system for a specific altitude layer of turbulence, providing support for the further enhancement of GLAO performance. The simulation results indicate that the LCE has high applicability in GLAO performance analysis.

Ocular aberration measurement with and without an aperture stop using a Shack-Hartmann wavefront sensor.

Pupil size is an important parameter since it governs the magnitude of ocular aberrations. The pupil size of a human eye has significant individual differences and varies with light level and accommodation. In order to accurately measure ocular aberrations under different pupil sizes using a Shack-Hartmann wavefront sensor (SHWFS), two types of relationship matrices R (1) and R (2) were proposed, which corresponded to wavefront reconstruction with and without an aperture stop, respectively. The numerical and experimental results indicated that matrix R (2) can significantly improve the accuracy of wavefront restoration when the incident beam size is inconsistent with the wavefront reconstruction aperture. Meanwhile, the impact of the aperture stop on the reconstruction accuracy will become smaller and smaller as the ratio ρ of the outer area to the detection aperture decreases. This study not only can be used for accurately measuring ocular aberrations under different pupil sizes, but also for other variable aperture aberrations measurement in other applications.

Enhanced-resolution Shack-Hartmann wavefront sensing for extended objects.

Adaptive optics systems for large-aperture solar telescopes, especially multiconjugate adaptive optics systems, suffer from a fundamental trade-off between wavefront sampling rate and sub-aperture resolution. We introduce an enhanced-resolution Shack-Hartmann wavefront sensing method that decouples sub-aperture resolution from the desired wavefront sampling rate. We experimentally verified the validity of this method. Results show that by synthesizing multiple low-spatial samplings, this method is capable to sense higher-frequency aberrations beyond any low-spatial sampling involved in the synthesis, and it allows higher sub-aperture resolution and higher operating bandwidths, which can better fulfill the needs of solar adaptive optics.

Study on optimization of multi-UAV nucleic acid sample delivery paths in large cities under the influence of epidemic environment.

In the context of global novel coronavirus infection, we studied the distribution problem of nucleic acid samples, which are medical supplies with high urgency. A multi-UAV delivery model of nucleic acid samples with time windows and a UAV (Unmanned Aerial Vehicle) dynamics model for multiple distribution centers is established by considering UAVs' impact cost and trajectory cost. The Golden Eagle optimization algorithm (SGDCV-GEO) based on gradient optimization and Corsi variation is proposed to solve the model by introducing gradient optimization and Corsi variation strategy in the Golden Eagle optimization algorithm. Performance evaluation by optimizing test functions, Friedman and Nemenyi test compared with Golden Jackal Optimization (GJO), Hunter-Prey Optimization (HPO), Pelican Optimization Algorithm (POA), Reptile Search Algorithm (RSA) and Golden Eagle Optimization (GEO), the convergence performance of SGDCV-GEO algorithm was demonstrated. Further, the improved RRT (Rapidly-exploring Random Trees) algorithm is used in the UAV path planning, and the pruning process and logistic chaotic mapping strategy are introduced in the path generation method. Finally, simulation experiments are conducted based on 8 hospitals and 50 randomly selected communities in the Pudong district of Shanghai, southern China. The experimental results show that the developed algorithm can effectively reduce the delivery cost and total delivery time compared with simulated annealing algorithm (SA), crow search algorithm (CSA), particle swarm algorithm (PSO), and taboo search algorithm (TS), and the developed algorithm has good uniformity, robustness, and high convergence accuracy, which can be effectively applied to the multi-UAV nucleic acid sample delivery path optimization in large cities under the influence of an epidemic environment.

Dynamic Response and Damage Accumulation of Laminated Composites under Repeated Low-Velocity Impacts.

The mechanical response and damage accumulation of carbon-fiber-reinforced composite laminates subjected to repeated low-velocity impacts were experimentally investigated. The repeated impact tests were conducted on [902/-452/02/452]S quasi-isotropic and [902/02]2S cross-ply composite laminates under 16.8 J impact energy, respectively. For each impact, impact responses such as force-time, force-displacement and energy-time curves were recorded. The trends of peak force, maximum central displacement, energy absorption rate and bending stiffness with the increasing impact number were summarized, and the maximum number of repeated impacts corresponded to the occurrence of penetration events. The results showed that the delamination initiation, fiber breakage and penetration were the three typical characteristics describing the damage evolution of the repeated impacts. The damage accumulation of both the laminates was characterized by employing appropriate damage indices. By contrast, the quasi-isotropic laminates had higher impact resistance and damage tolerance, and their damage accumulation was relatively slower.

Micromechanisms and Characterization of Low-Velocity Impact Damage in 3D Woven Composites.

Low-velocity impact (LVI) damage of 3D woven composites were experimentally and numerically investigated, considering different off-axis angles and impact energies. The impact responses were examined by LVI tests, and the damage morphology inside the composites was observed by X-ray micro-computed tomography (µ-CT). Yarn-level damage evolution was revealed by developing a hybrid finite element analysis model. The results show that the impact damage has significant directionality determined by the weft/warp orientation of the composites. The damage originates at the bottom of the impacted area and then expands outwards and upwards simultaneously, accompanied by in-plane and out-of-plane stress transfers. The straight-line distributed weft/warp yarns play an important role in bearing loads at the beginning of loading, while the w-shape distributed binder warp yarns gradually absorb impact deformation and toughen the whole structure as the loading proceeds. The effect of directional impact damage on post-impact performance was explored by performing compressing-after-impact (CAI) tests. It is revealed that the CAI properties along principal directions are more sensitive to the low-velocity impact, and the damage mode is significantly affected by the loading direction.

Region-correlation algorithm with improved dynamic range and reconstruction accuracy for extended object wavefront sensing.

The correlation Shack-Hartmann wavefront sensor (SHWFS) is widely used in many fields in addition to solar adaptive optics. The requirement for the SHWFS dynamic range increases with the diameter of the telescope, which means a larger detector array is needed. However, the size of the detector would be restricted by the high frame rate needed for the solar observation. To solve this problem, a new, to the best of our knowledge, method called the region-correlation algorithm (RCA) is proposed. In this method, the sub-image array is divided into several regions, and the slopes of sub-apertures are calculated by referring to a selected sub-image in each region. Note that the final slope over a sub-aperture is obtained by combining the relative slopes between the selected sub-image in different regions. The dynamic range in each region is similar to the conventional correlation algorithm, and the final dynamic range of the RCA would be accumulated from those of the regions. The reconstruction accuracy under large aberration would also be improved due to the extended dynamic range. Meanwhile, the RCA does not require any extra device and the increase in calculation time resulting from the RCA is acceptable. The results of numerical simulation and experiment, compared with conventional correlation algorithm, confirm the advantages in the performance of the RCA as well.

Oblique Low-Velocity Impact Response and Damage Behavior of Carbon-Epoxy Composite Laminates.

The low-velocity impact behavior of carbon-epoxy cross-ply composites was numerically investigated, examining the effect of impact angle. A plastic continuum damage model, introducing the cohesive interface to describe delamination damage, was established and was validated by available experimental data. Impact histories, progressive deformation, stress transfer, and impact damage are respectively discussed. The results show that an increase in impact angle intensifies the action of tangential force, and gradually transfers energy absorption from normal plastic deformation to tangential deformation and friction, which dissipates more energy through relatively longer contact duration and larger impactor displacement. The delamination damage to upper layers is more affected by tangential loads, intensifying with the increase of the impact angle, and the damage area to the top interface is increased by 132.1% from 0° impact to 60° impact. Meanwhile, the delamination damage to lower layers is mainly determined by normal loads, weakening with the increasing impact angle overall, and the damage area of the lowest interface decreases by 36.6% from 0° impact to 60° impact.

Full-Stokes Retrieving and Configuration Optimization in a Time-Integration Imaging Polarimeter.

A time-integration imaging polarimeter with continuous rotating retarder is presented, and its full-Stokes retrieving and configuration optimization are also demonstrated. The mathematical expression between the full-Stokes vector and the time-integration light intensities is derived. As a result, the state of polarization of incident light can be retrieved by only one matrix calculation. However, the modulation matrix deviates from the initial well-conditioned status due to time integration. Thus, we re-optimize the nominal angles for the special retardance of 132° and 90° with an exposure angle of 30°, which results in a reduction of 31.8% and 16.8% of condition numbers comparing to the original configuration, respectively. We also give global optimization results under different exposure angles and retardance of retarder; as a result, the 137.7° of retardance achieves a minimal condition number of 2.0, which indicates a well-conditioned polarimeter configuration. Besides, the frame-by-frame algorithm ensures the dynamic performance of the presented polarimeter. For a general brushless DC motor with a rotating speed of over 2000 rounds per minute, the speed of polarization imaging will achieve up to 270 frames per second. High precision and excellent dynamic performance, together with features of compactness, simplicity, and low cost, may give this traditional imaging polarimeter new life and attractive prospects.

PLCE1 is a poor prognostic marker and may promote immune escape from osteosarcoma by the CD70-CD27 signaling pathway.

Phospholipase C epsilon 1 (PLCE1) is involved in the pathogenesis of many cancers. However, the biological role of PLCE1 in osteosarcoma (OS) is still poorly understood. The prognostic survival analysis was performed on the PLCE1gene in the TARGET data set and the differential expression of PLCE1 in OS tissue and normal bone tissue on the tissue chip was detected by immunohistochemistry. Spearman's rank correlation coefficient analysis was implemented to explore the relationship between PLCE1 and immune genes. Finally, PLCE1 was silenced to explore its biological function in OS cells. The results of tissue chip immunohistochemistry showed that PLCE1 expression in OS tissue was higher than in normal bone tissue. The survival curve of PLCE1 and its corresponding receiver operating characteristic curve (ROC) showed that PLCE1 had a significant effect on the survival status of patients with OS and that the prognosis of patients with high PLCE1 expression was relatively poor. Spearman's rank correlation coefficient analysis and qRT-PCR assays found that PLCE1 may promote immune escape from OS via CD70-CD27 signaling pathway. Silencing of PLCE1 causes the following biological behaviors of OS cells: it promotes apoptosis, inhibits proliferation of OS cells, and inhibits the ability of cell migration and invasion. PLCE1 is a poor prognostic marker and a potential key factor affecting the immune status of the OS tumor microenvironment.

Polarization imaging based on time-integration by a continuous rotating polarizer.

Polarimeter by rotating polarizer is one of the well-known and classic division of time polarimeter (DoTP). It is generally acknowledged that this kind of polarimeter is time consuming for each measurement although it has simple, accurate and compact performances. In this paper we present a time-integration polarimeter by using a continuous rotating polarizer. The basic principle and the corresponding mathematical expressions are derived. Numeric analysis and experiments are also made in this paper. Experimental results validate the precision and feasibility of the proposed imaging polarization and state of polarization retrieve theory. The frame-frequency of polarization image is 80fps which is limited mainly by the speed of the photodetector in our experiments, and its maximum frame-frequency can achieve over 270fps in theory for some special applications. That may give this kind of classic polarimeter new attractive prospects and life.

Single preloaded piezoelectric-ceramic-stack-actuator-based fast steering mirror with an ultrahigh natural frequency.

To meet the requirements of the adaptive optics systems with high bandwidths and large excursion angles, we propose a fast steering mirror (FSM) with an ultrahigh natural frequency and a large angular range. The proposed FSM is driven by a preloaded piezoelectric ceramic stack actuator (PCSA), which has a higher shear stress limit in the working direction. We describe the structure of the preloading device and analyze the stiffness improvement of the preloaded PCSA. Then we introduce the structure of the proposed FSM and perform theoretical analysis based on the established static model and dynamical model. We also build an experimental setup of the proposed FSM. The experimental results show that the angular range of the proposed FSM is up to 8.4 mrad, and its first natural frequency is 6660 Hz, which surpass the performances of current FSMs.

LncRNA PCAT6 promotes tumor progression in osteosarcoma via activation of TGF-ß pathway by sponging miR-185-5p.

Long noncoding RNAs (lncRNAs) play crucial roles in tumor development of osteosarcoma (OS). LncRNA PCAT6 was involved in the progression of multiple human cancers. However, the biological function of PCAT6 in OS remains largely unknown. We found that PCAT6 was elevated in OS tissues relative to that in their adjacent normal tissues. The upregulation of PCAT6 was positively associated with metastasis status and advanced stages and predicted poor overall and progression-free survivals in patients with OS. Functionally, silencing PCAT6 inhibited the proliferation, migration and invasion abilities of OS cells. Mechanistically, PCAT6, acting as a competitive endogenous RNA, upregulated expression of TGFBR1 and TGFBR2 to activate TGF-ß pathway via sponging miR-185-5p. This study uncovers a novel underlying molecular mechanism of PCAT6-miR-185-5p-TGFBR1/2-TGF-ß signaling axis in promoting tumor progression in OS, which indicates that PCAT6 may serve as a promising prognostic factor and therapeutic target again OS.

Compact single-shot radial shearing interferometer with random phase shift.

We propose a compact phase-shifting radial shearing interferometer based on a pixelated micro-retarder array (MRA). The MRA is made of a thin birefringence plate, and is composed of identical units that have pixels of four different thicknesses. We demonstrate that pixelated phase delay between two shearing beams can be introduced by applying the fast axis of birefringence plate in the horizontal or vertical orientation. We also present an approach to extract the wavefront under test with random phase shift, which dramatically reduces the machining difficulty of the MRA. The feasibility and accuracy of the proposed method are further validated through our numerical analysis. With the advantages of vibration immunity, simultaneous phase stepping, and broad spectral range, the presented interferometer is expected to be of potential use in a variety of applications, such as the detection of moving objects and dynamic processes.

Experimental study of a modified phase diversity with a diffraction grating.

The measurement ability of the conventional Phase diversity wavefront sensor (C-PD WFS) is limited by the accuracy and dynamic range of CCD cameras. In this letter, a modified Phase diversity wavefront sensor based on a diffraction grating (G-PD WFS) is proposed. We build a corresponding experimental setup to compare the measurement accuracy of the G-PD WFS and the C-GPDWFS under the same experimental conditions. The experimental results show that the measurement ability of G-PD WFS is improved obviously, especially for the wavefront aberration with larger amplitude.

Modal wavefront reconstruction for radial shearing interferometer with lateral shear.

In a radial shearing interferometer, a portion of the test beam is magnified and used as the reference for the tested wavefront. However, the reference portion is always off center (lateral shear), which complicates the wavefront reconstruction. A modal method for solving this problem is presented here. This method uses orthogonal Zernike polynomials and its matrix formalism to calculate the Zernike coefficient of the wavefront under test. This approach has easier implementation, is better filtering, and has a more adaptive practical situation. The corresponding mathematical formula is deduced, and a computer simulation is also made to verify operation of the algorithm. The result of simulation analysis shows that the proposed method is correct and accurate.

A single-shot common-path phase-stepping radial shearing interferometer for wavefront measurements.

A single-shot common-path phase-stepping radial shearing interferometer (RSI) is proposed for wavefront measurements. In the proposed RSI, three quarter-wave plates are used as phase shifters to produce four spatially separated phase-stepping fringe patterns that are recorded simultaneously by a single CCD camera. The proposed RSI can measure the wavefront under test in real-time, and it is also insensitive to environmental vibration due to its common-path structure. Experimentally the proposed RSI is applied to detect the distorted wavefronts generated by a liquid crystal spatial light modulator. The measured aberrations are in good agreement with that obtained with (by) a Hartmann-Shack wavefront sensor, indicating that the proposed RSI is a useful tool for wavefront measurements.

Comparison between non-modulation four-sided and two-sided pyramid wavefront sensor.

Based on the diffraction theory the paper analyzes non-modulation Pyramid wavefront sensor (PWFS, namely, four-sided pyramid) and two-sided pyramid wavefront sensor (TSPWFS), and expresses the detected signals as a function of the measured wavefront. The expressions of the detected signals show that non-modulation PWFS and TSPWFS hold the same properties of both slope and direct phase sensors. We compare both sensors working in slope and phase sensing by theory and numerical simulations. The results demonstrate that the performance of TSPWFS excels that of PWFS. Additionally, the influence of interference between adjacent pupils is discussed.

Modified Gaussian influence function of deformable mirror actuators.

A new deformable mirror influence function based on a Gaussian function is introduced to analyze the fitting capability of a deformable mirror. The modified expressions for both azimuthal and radial directions are presented based on the analysis of the residual error between a measured influence function and a Gaussian influence function. With a simplex search method, we further compare the fitting capability of our proposed influence function to fit the data produced by a Zygo interferometer with that of a Gaussian influence function. The result indicates that the modified Gaussian influence function provides much better performance in data fitting.