Wide-spectrum optical synthetic aperture imaging via spatial intensity interferometry

High resolution imaging is achieved using increasingly larger apertures and successively shorter wavelengths.Optical aperture synthesis is an important high-resolution imaging technology used in astronomy.Conventional long baseline amplitude interferometry is susceptible to uncontrollable phase fluctuations,and the technical difficulty increases rapidly as the wavelength decreases.The intensity interferometry inspired by HBT experiment is essentially insensitive to phase fluctuations,but suffers from a narrow spectral bandwidth which results in a lack of effective photons.In this study,we propose optical synthetic aperture imaging based on spatial intensity interferometry.This not only realizes diffraction-limited optical aperture synthesis in a single shot,but also enables imaging with a wide spectral bandwidth,which greatly improves the optical energy efficiency of intensity interferometry.And this method is insensitive to the optical path difference between the sub-apertures.Simulations and experiments present optical aperture synthesis diffraction-limited imaging through spatial intensity interferometry in a 100 nm spectral width of visible light,whose maximum optical path difference between the sub-apertures reaches 69λ.This technique is expected to provide a solution for optical aperture synthesis over kilometer-long baselines at optical wavelengths.

76例初诊EGFR突变阳性合并胸腔积液肺腺癌患者的临床特征及预后分析:一项单中心、回顾性研究

背景与目的 恶性胸腔积液是肺腺癌患者常见临床表现之一,肺腺癌初诊时合并胸腔积液提示预后不佳。表皮生长因子受体(epidermal growth factor receptor,E GFR)突变主要发生在肺腺癌患者中,不同亚型预后不同。初诊时不同亚型EGFR突变阳性合并胸腔积液肺腺癌患者的临床特征及预后因素目前尚不明确,本研究拟探讨此类患者的临床特征及预后影响因素,旨在为此类患者提供诊治参考。方法 回顾性分析2012年1月-2021年6月期间,北京大学第三医院肿瘤化疗与放射病科收治的初诊时EGFR突变阳性且合并胸腔积液肺腺癌患者的临床特征、治疗方法 、治疗疗效和一线治疗中位无进展生存期(progression-free survival,PFS),采用Pearson卡方检验或Fisher精确概率法进行组间比较,采用Kaplan-Meier法进行生存分析,采用Cox比例风险回归模型进行多因素分析。结果 共筛选出符合入组条件的患者76例,EGFR经典突变19del、21L858R和非经典突变的发生率分别为46.0%、38.2%和15.8%,3种突变亚型在性别、年龄、发病时有无呼吸困难、是否合并其他远处转移、胸腔积液部位、胸腔积液量、有无合并其他部位积液、肿瘤原发灶-淋巴结-转移(tumor-node-metastasis,TNM)分期、有无合并其他基因突变、胸腔积液的治疗方法 等方面无显著差异(P>0.05)。在EGFR经典突变19del、21L858R和非经典突变患者中,一线应用化疗的占比分别为17.1%、20.7%和58.3%(P=0.001);一线疾病控制率分别为94.3%、75.9%和50.0%(P=0.003);胸腔积液控制率分别为94.3%、79.3%和66.7%(P=0.04);PFS分别为287 d、327 d和55 d (P=0.001)。单因素分析显示EGFR突变亚型、胸腔积液控制情况、一线治疗药物、一线治疗疗效与PFS显著相关(P<0.05),Cox多因素分析显示仅EGFR突变类型、一线治疗疗效是PFS的独立预后因素(P<0.05)。结论 初诊EGFR突变阳性且合并胸腔积液的肺腺癌患者中,EGFR经典突变(19del和21L858R)患者的PFS显著优于非经典突变者,提升一线治疗疗效是改善此类患者预后的关键。

“内外联动,三点一线”,助力复养工作

中国是世界养猪大国,同时也是全世界第一猪肉消费大国。非洲猪瘟的暴发给中国的生猪养殖行业带来了巨大冲击。生猪存栏数量下降,散户大部分退出,使得市场上的猪肉供给受到一定程度的影响。依靠从国外进口猪肉来解决国内的消费需求能够起到一定的缓冲作用。但从长远考虑,如何防治非洲猪瘟,抓住“复养”环节所需,才是治本之道。文章借鉴已有研究成果,从政策背景出发,对复养环节的问题和注意事项进行论述,结合四川省和江苏省的成功案例,旨在为生猪养殖业的复养工作提供参考和建议。

减抗、限抗对生猪养殖行业的影响分析

2018年4月20日,农业农村部出台了《兽用抗菌药使用减量化行动试点工作方案(2018-2021年)》(以下简称《方案》)。从国家层面来看,《方案》旨在通过推进养殖业的绿色发展进程,从而进一步实现振兴乡村这一伟大目标。对于畜牧业而言,国家的此项举措无疑是为了促进畜牧行业的长远发展,但是在实施过程中,势必会与当下的养殖现状产生一些冲突。对于这些冲突,我们需要分析其成因及影响,从而为保证方案的顺利实施提供可供参考的措施。文章以生猪养殖为例,结合《方案》出台的背景,从可能出现的问题以及应对措施等方面进行分析、论述,从而为养猪人应对减抗、限抗提供参考依据。

A Facial Expression Emotion Recognition Based Human-robot Interaction System

A facial expression emotion recognition based human-robot interaction(FEER-HRI) system is proposed, for which a four-layer system framework is designed. The FEERHRI system enables the robots not only to recognize human emotions, but also to generate facial expression for adapting to human emotions. A facial emotion recognition method based on2D-Gabor, uniform local binary pattern(LBP) operator, and multiclass extreme learning machine(ELM) classifier is presented,which is applied to real-time facial expression recognition for robots. Facial expressions of robots are represented by simple cartoon symbols and displayed by a LED screen equipped in the robots, which can be easily understood by human. Four scenarios,i.e., guiding, entertainment, home service and scene simulation are performed in the human-robot interaction experiment, in which smooth communication is realized by facial expression recognition of humans and facial expression generation of robots within 2 seconds. As a few prospective applications, the FEERHRI system can be applied in home service, smart home, safe driving, and so on.

畜禽养殖废弃物资源化利用政策梳理——以河北省生猪养殖为例

随着我国生猪养殖规模逐渐扩大,生猪养殖过程中废弃物数量也在不断增加,养殖废弃物污染问题也日益受到重视。由于生猪养殖废弃物存在利用不合理、不充分等情况,使得土地污染、空气污染和水源污染问题对人们生产和生活的负面影响也越来越大。河北省是生猪养殖和猪肉消费大省,每年有大量废弃物不断产生,其在一定程度上困扰着养殖主体和相关政府部门。废弃物无害化处理等制度顺利出台使得生猪粪污资源化利用得到有效发展。文章通过对2016年3月-2020年4月期间,国家和河北省政府相关部门出台的资源化利用政策进行汇总分析,结合河北省当前生猪养殖废弃物资源化利用现状,旨在推进畜禽废弃物资源化利用进程,推进养殖主体更好利用相关政策。

2019年养猪业新兽药盘点

兽药作为养殖行业的一项重要组成部分,在各个国家、地区的畜禽养殖环节中都不可或缺,而新兽药的研发更是为畜禽更好地繁衍生长和疫情的更有效防控提供了有力保障。我国是生猪养殖、进出口及猪肉消费大国。近年来国家对于养猪业在内的新型兽药的研发和应用愈加重视。据相关资料统计,2018年共有25种针对生猪产业的新型兽药得到国家农业农村部的认可,并给予注册证书号[1]。2018年8月至今,我国养猪业受到非洲猪瘟的影响较大,在防控非洲猪瘟药物研发上的投入也比较多,但从目前的成果来看,防控非洲猪瘟的药物研发仍是接下来的重要目标之一。

Physical picture of the optical memory effect

The optical memory effect is an interesting phenomenon that has attracted considerable attention in recent decades. Here, we present a new physical picture of the optical memory effect, in which the memory effect and the conventional spatial shift invariance are united. Based on this picture we depict the role of thickness, scattering times, and anisotropy factor and derive equations to calculate the ranges of the angular memory effect(AME) of different scattering components(ballistic light, singly scattered, doubly scattered, etc.), and hence a more accurate equation for the real AME ranges of volumetric turbid media. A conventional random phase mask model is modified according to the new picture. The self-consistency of the simulation model and its agreement with the experiment demonstrate the rationality of the model and the physical picture, which provide powerful tools for more sophisticated studies of the memory-effect-related phenomena and wavefront-sensitive techniques, such as wavefront shaping, optical phase conjugation, and optical trapping in/through scattering media.

Preconditioned deconvolution method for high-resolution ghost imaging

Ghost imaging(GI)can nonlocally image objects by exploiting the fluctuation characteristics of light fields,where the spatial resolution is determined by the normalized second-order correlation function g^(2) .However,the spatial shift-invariant property of g^(2) is distorted when the number of samples is limited,which hinders the deconvolution methods from improving the spatial resolution of GI.In this paper,based on prior imaging systems,we propose a preconditioned deconvolution method to improve the imaging resolution of GI by refining the mutual coherence of a sampling matrix in GI.Our theoretical analysis shows that the preconditioned deconvolution method actually extends the deconvolution technique to GI and regresses into the classical deconvolution technique for the conventional imaging system.The imaging resolution of GI after preconditioning is restricted to the detection noise.Both simulation and experimental results show that the spatial resolution of the reconstructed image is obviously enhanced by using the preconditioned deconvolution method.In the experiment,1.4-fold resolution enhancement over Rayleigh criterion is achieved via the preconditioned deconvolution.Our results extend the deconvolution technique that is only applicable to spatial shift-invariant imaging systems to all linear imaging systems,and will promote their applications in biological imaging and remote sensing for high-resolution imaging demands.

Alternative Interpretation of Speckle Autocorrelation Imaging Through Scattering Media

High-resolution optical imaging through or within thick scattering media is a long sought after yet unreached goal.In the past decade,the thriving technique developments in wavefront measurement and manipulation do not significantly push the boundary forward.The optical diffusion limit is still a ceiling.In this work,we propose that a scattering medium can be conceptualized as an assembly of randomly packed pinhole cameras and the corresponding speckle pattern as a superposition of randomly shifted pinhole images.The concept is demonstrated through both simulation and experiments,confirming the new perspective to interpret the mechanism of information transmission through scattering media under incoherent illumination.We also analyze the efficiency of single-pinhole and dual-pinhole channels.While in infancy,the proposed method reveals a new perspective to understand imaging and information transmission through scattering media.

Lensless Wiener–Khinchin telescope based on second-order spatial autocorrelation of thermal light

The resolution of a conventional imaging system based on first-order field correlation can be directly obtained from the optical transfer function. However, it is challenging to determine the resolution of an imaging system through random media, including imaging through scattering media and imaging through randomly inhomogeneous media, since the point-to-point correspondence between the object and the image plane in these systems cannot be established by the first-order field correlation anymore. In this Letter, from the perspective of ghost imaging, we demonstrate for the first time, to the best of our knowledge, that the point-to-point correspondence in these imaging systems can be quantitatively recovered from the second-order correlation of light fields, and the imaging capability, such as resolution, of such imaging schemes can thus be derived by analyzing second-order autocorrelation of the optical transfer function. Based on this theoretical analysis, we propose a lensless Wiener–Khinchin telescope based on second-order spatial autocorrelation of thermal light, which can acquire the image of an object by a snapshot via using a spatial random phase modulator. As an incoherent imaging approach illuminated by thermal light, the lensless Wiener–Khinchin telescope can be applied in many fields such as X-ray astronomical observations.

Imaging through dynamic scattering media with stitched speckle patterns

Imaging through scattering media via speckle autocorrelation is a popular method based on the optical memory effect.However,it fails if the amount of valid information acquired is insufficient due to a limited sensor size.In this Letter,we reveal a relationship between the detector and object sizes for the minimum requirement to ensure image reconstruction by defining a sampling ratio R,and propose a method to enhance the image quality at a small R by capturing multiple frames of speckle patterns and piecing them together.This method will be helpful in expanding applications of speckle autocorrelation to remote sensing,underwater probing,and so on.

Dispersion control of broadband super-Rayleigh speckles for snapshot spectral ghost imaging

Snapshot spectral ghost imaging,which can acquire dynamic spectral imaging information in the field of view,has attracted increasing attention in recent years.Studies have shown that optimizing the fluctuation of light fields is essential for improving the sampling efficiency and reconstruction quality of ghost imaging.However,the optimization of broadband light fields in snapshot spectral ghost imaging is challenging because of the dispersion of the modulation device.In this study,by judiciously introducing a hybrid refraction/diffraction structure into the light-field modulation,snapshot spectral ghost imaging with broadband super-Rayleigh speckles was demonstrated.The simulation and experiment results verified that the contrast of speckles in a broad range of wavelengths was significantly improved,and the imaging system had superior noise immunity.

Study of the automotive aerodynamic performance affected by entrance structure of forecabin

Recently,the requirement for cooling capacity decreased when the driving energy changed from liquid fuel to lithium batteries.Therefore,the structure and location of the forecabin could be adjusted based on the aerody-namic performance.The current study conducted a significant number of simulations in order to find out the effects of the internal flow through forecabin in an Ahmed body.The following conclusions have been identi-fied:1,The flow through the forecabin would always increase the resistance of the entire body,and the drag coefficient increases,on average,by approximately 85%.2,When the aspect ratio is higher or the position of the inlet opening is lower,the total drag coefficient is lower due to a weaker vortex strength,a simpler vortex structure and a relatively simple flow.3,The existence of the forecabin will largely increase the oscillation fre-quency of the flow field by approximately 15 times compared to the original Ahmed model.Finally,the high drag coefficient moment always appears to be due to the formation of more complex or intense vortex motion.These conclusions can offer useful results and references for the structural design of the front cabin for new energy vehicles.

A Complex Background Image Registration Method Based on the Optical Flow Field Algorithm

An effective nonrigid image registrationmethod is developed based on the optical flow field(OFF)framework for the complex registration of structure images.In our method,a new force is modeled and integrated into the original optical flow equation to jointly drive the motion direction of pixels.At any point in the offset field,in addition to the force generated by the OFF model derived from local gradient information to drive the pixels in the floating image to infiltrate into the reference pixel set,a new“guiding force”derived from the global grayscale overall trend in a given neighborhood system helps the pixels to more properly spread into the corresponding reference pixel set,particularly when the gradient field of the reference image is unstable.In the experiment,a data set containing several images with complex structures was employed to validate the performance of our registration model.The test results show that our method can quickly and efficiently register complex images and is robust to noise in images.

A Low Spectral Bias Generative Adversarial Model for Image Generation

We propose a systematic analysis of the neglected spectral bias in the frequency domain in this paper.Traditional generative adversarial networks(GANs)try to fulfill the details of images by designing specific network architectures or losses,focusing on generating visually qualitative images.The convolution theorem shows that image processing in the frequency domain is parallelizable and performs better and faster than that in the spatial domain.However,there is little work about discussing the bias of frequency features between the generated images and the real ones.In this paper,we first empirically demonstrate the general distribution bias across datasets and GANs with different sampling methods.Then,we explain the causes of the spectral bias through the deduction that reconsiders the sampling process of the GAN generator.Based on these studies,we provide a low-spectral-bias hybrid generative model to reduce the spectral bias and improve the quality of the generated images.