Effects of Early-stage Phased Rehabilitation Training on Acute Respiratory Distress Syndrome:A Systematic Review and Meta-analysis

[Objectives]To systematically evaluate the effects of early-stage phased rehabilitation training on the oxygenation index,ICU length of stay,duration of mechanical ventilation,and occurrence of complications(ventilator-associated pneumonia,pressure ulcers,delirium)in ARDS patients,thus contributing evidence for the clinical application of early-stage phased rehabilitation training.[Methods]The China National Knowledge Infrastructure(CNKI),Wanfang,and other databases were searched.Literature screening,data extraction,and systematic analysis of the included studies were performed using Revman software.[Results]Thirteen randomized controlled trials involving a total of 860 patients were included in this review.The results of the meta-analysis showed that compared to the traditional rehabilitation training group,the early-stage phased rehabilitation training group demonstrated a significant increase in the oxygenation index of ARDS patients[SMD=1.18,95%CI(1.01,1.35),P<0.01],with statistically significant differences.Furthermore,there were significant reductions in ICU length of stay[SMD=-0.70,95%CI(-0.90,-0.50),P<0.01],duration of mechanical ventilation[SMD=-1.15,95%CI(-1.36,-0.94),P<0.01],and occurrence of complications[OR=0.16,95%CI(0.10,0.26),P<0.01],all of which were statistically significant.[Conclusions]Early-stage phased pulmonary rehabilitation training for ARDS patients effectively improves the oxygenation index,shortens ICU length of stay and duration of mechanical ventilation,and reduces complications.These findings support the clinical application and promotion of early-stage phased rehabilitation training.

Different environmental factors drive tree species diversity along elevation gradients in three climatic zones in Yunnan,southern China

Elevational patterns of tree diversity are well studied worldwide.However,few studies have examined how seedlings respond to elevational gradients and whether their responses vary across climatic zones.In this study,we established three elevational transects in tropical,subtropical and subalpine mountain forests in Yunnan Province,southern China,to examine the responses of tree species and their seedlings to elevational gradients.Within each transect,we calculated species diversity indices and composition of both adult trees and seedlings at different elevations.For both adult trees and seedlings,we found that species diversity decreased with increasing elevation in both tropical and subalpine transects.Species composition showed significant elevational separation within all three transects.Many species had specific elevational preferences,but abundant tree species that occurred at specific elevations tended to have very limited recruitment in the understory.Our results highlight that the major factors that determine elevational distributions of tree species vary across climatic zones.Specifically,we found that the contribution of air temperature to tree species composition increased from tropical to subalpine transects,whereas the contribution of soil moisture decreased across these transects.

Scalable parallel ultrafast optical random bit generation based on a single chaotic microcomb

Random bit generators are critical for information security,cryptography,stochastic modeling,and simulations.Speed and scalability are key challenges faced by current physical random bit generation.Herein,we propose a massively parallel scheme for ultrafast random bit generation towards rates of order 100 terabit per second based on a single micro-ring resonator.A modulation-instability-driven chaotic comb in a micro-ring resonator enables the simultaneous generation of hundreds of independent and unbiased random bit streams.A proof-of-concept experiment demonstrates that using our method,random bit streams beyond 2 terabit per second can be successfully generated with only 7 comb lines.This bit rate can be easily enhanced by further increasing the number of comb lines used.Our approach provides a chip-scale solution to random bit generation for secure communication and high-performance computation,and offers superhigh speed and large scalability.

Hyperbolic resonant radiation of concomitant microcombs induced by cross-phase modulation

A high-quality optical microcavity can enhance optical nonlinear effects by resonant recirculation,which provides a reliable platform for nonlinear optics research.When a soliton microcomb and a probe optical field are coexisting in a micro-resonator,a concomitant microcomb(CMC)induced by cross-phase modulation(XPM)will be formed synchronously.Here,we characterize the CMC comprehensively in a micro-resonator through theory,numerical simulation,and experimental verification.It is found that the CMCs spectra are modulated due to resonant radiation(RR)resulting from the interaction of dispersion and XPM effects.The group velocity dispersion induces symmetric RRs on the CMC,which leads to a symmetric spectral envelope and a dual-peak pulse in frequency and temporal domains,respectively,while the group velocity mismatch breaks the symmetry of RRs and leads to asymmetric spectral and temporal profiles.When the group velocity is linearly varying with frequency,two RR frequencies are hyperbolically distributed about the pump,and the probe light acts as one of the asymptotic lines.Our results enrich the CMC dynamics and guide microcomb design and applications such as spectral extension and dark pulse generation.

西双版纳望天树林种子雨9年动态

种子雨是森林生态系统过程的重要组成部分。虽然国内外已有部分关于种子雨的研究,但多数集中在温带和亚热带地区,热带地区种子雨的长期监测研究仍显不足。为全面了解热带森林种子雨输入的数量动态和物种组成的长期规律,本文对我国西双版纳望天树(Parashoreachinensis)林群落水平上9年(2008年5月至2017年4月)的种子雨输入进行了研究。9年共收集到木本植物的种子226种8,993,224粒,其中大型种子(I-1型) 77种9,779粒;中型种子(I-2型)61种24,237粒;小型种子(I-3型)72种83,399粒;粒状微小种子(II-1型)13种1,215,235粒;粒状极小种子(II-2型) 1种7,244,667粒;细丝状种子(II-3型) 2种415,907粒。种子雨输入量排名前10位的优势种贡献了70%以上的种子数量。各类型种子的种子雨输入量均具有年际波动,呈"大小年"的交替变化,间隔期为1–2年,物种组成也呈现一定的年际差异。持续9年的监测中,每类型种子至少观察到了1次大年结实事件。

Long-distance ranging with high precision using a soliton microcomb

Laser-based light detection and ranging(lidar)plays a significant role in both scientific and industrial areas.However,it is difficult for existing lidars to achieve high speed,high precision,and long distance simultaneously.Here,we demonstrate a high-performance lidar based on a chip-scaled soliton microcomb(SMC)that can realize all three specialties simultaneously.Aided by the excellent properties of ultrahigh repetition rate and the smooth envelope of the SMC,traditional optical frequency comb(OFC)-based dispersive interferometry is heavily improved and the measuring dead zone induced by the mismatch between the repetition rate of the OFC and resolution of the optical spectrum analyzer is totally eliminated.Combined with an auxiliary dual-frequency phase-modulated laser range finder,the none-dead-zone measurable range ambiguity is extended up to 1500 m.The proposed SMC lidar is experimentally implemented in both indoor and outdoor environment.In the outdoor baseline field,real-time,high-speed(up to 35 k Hz)measurement of a long distance of^1179 m is achieved with a minimum Allan deviation of 5.6μm at an average time of 0.2 ms(27 nm at an average time of 1.8 s after high-pass filtering).The present SMC lidar approaches a compact,fast,high-precision,and none-dead zone long-distance ranging system,aimed at emerging applications of frontier basic scientific research and advances in industrial manufacturing.

Advances in soliton microcomb generation

Optical frequency combs,a revolutionary light source characterized by discrete and equally spaced frequencies,are usually regarded as a cornerstone for advanced frequency metrology,precision spectroscopy,high-speed communication,distance ranging,molecule detection,and many others.Due to the rapid development of micro/nanofabrication technology,breakthroughs in the quality factor of microresonators enable ultrahigh energy buildup inside cavities,which gives birth to microcavity-based frequency combs.In particular,the full coherent spectrum of the soliton microcomb(SMC)provides a route to low-noise ultrashort pulses with a repetition rate over two orders of magnitude higher than that of traditional mode-locking approaches.This enables lower power consumption and cost for a wide range of applications.This review summarizes recent achievements in SMCs,including the basic theory and physical model,as well as experimental techniques for single-soliton generation and various extraordinary soliton states(soliton crystals,Stokes solitons,breathers,molecules,cavity solitons,and dark solitons),with a perspective on their potential applications and remaining challenges.

Genetic-algorithm-based deep neural networks for highly efficient photonic device design

While deep learning has demonstrated tremendous potential for photonic device design,it often demands a large amount of labeled data to train these deep neural network models.Preparing these data requires high-resolution numerical simulations or experimental measurements and cost significant,if not prohibitive,time and resources.In this work,we present a highly efficient inverse design method that combines deep neural networks with a genetic algorithm to optimize the geometry of photonic devices in the polar coordinate system.The method requires significantly less training data compared with previous inverse design methods.We implement this method to design several ultra-compact silicon photonics devices with challenging properties including power splitters with uncommon splitting ratios,a TE mode converter,and a broadband power splitter.These devices are free of the features beyond the capability of photolithography and generally in compliance with silicon photonics fabrication design rules.

Generation of coexisting high-energy pulses in a mode-locked all-fiber laser with a nonlinear multimodal interference technique

We demonstrate a passively mode-locked all-fiber laser incorporating a piece of graded-index multimode fiber as a mode-locking modulator based on a nonlinear multimodal interference technique, which generates two types of coexisting high-energy ultrashort pulses [i.e., the conventional soliton(CS) and the stretched pulse(SP)]. The CS with pulse energy as high as 0.38 n J is obtained at the pump level of 130 mW. When the pump increases to175 mW, the high-energy SP occurs at a suitable nonlinear phase bias and its pulse energy can reach 4 n J at a 610 mW pump. The pulse durations of the generated CS and SP are 2.3 ps and 387 fs, respectively. The theory of nonlinear fiber optics, single-shot spectral measurement by the dispersive Fourier-transform technique, and simulation methods based on the Ginzburg–Landau equation are provided to characterize the laser physics and reveal the underlying principles of the generated CS and SP. A rogue wave, observed between the CS and SP regions, mirrors the laser physics behind the dynamics of generating a high-energy SP from a CS. The proposed all-fiber laser is versatile, cost-effective and easy to integrate, which provides a promising solution for high-energy pulse generation.

Emerging material platforms for integrated microcavity photonics

Many breakthroughs in technologies are closely associated with the deep understanding and development of new material platforms.As the main material used in microelectronics,Si also plays a leading role in the development of integrated photonics.The indirect bandgap,absence ofχ(2)nonlinearity and the parasitic nonlinear absorptions at the telecom band of Si imposed technological bottlenecks for further improving the performances and expanding the functionalities of Si microcavities in which the circulating light intensity is dramatically amplified.The past two decades have witnessed the burgeoning of the novel material platforms that are compatible with the complementary metal-oxide-semiconductor(COMS)process.In particular,the unprecedented optical properties of the emerging materials in the thin film form have resulted in revolutionary progress in microcavity photonics.In this review article,we summarize the recently developed material platforms for integrated photonics with the focus on chip-scale microcavity devices.The material characteristics,fabrication processes and device applications have been thoroughly discussed for the most widely used new material platforms.We also discuss open challenges and opportunities in microcavity photonics,such as heterogeneous integrated devices,and provide an outlook for the future development of integrated microcavities.

Influences of multiphoton absorption and freecarrier effects on frequency-comb generation in normal dispersion silicon microresonators

We investigate frequency-comb generation in normal dispersion silicon microresonators from the near-infrared to mid-infrared wavelength range in the presence of multiphoton absorption and free-carrier effects. It is found that parametric oscillation is inhibited in the telecom wavelength range resulting from strong two-photon absorption.On the contrary, beyond the wavelength of 2200 nm, where three-and four-photon absorption are less detrimental,a comb can be generated with moderate pump power, or free-carriers are swept out by a positive-intrinsic-negative structure. In the temporal domain, the generated combs correspond to flat-top pulses, and the pulse duration can be easily controlled by varying the laser detuning. The reported comb generation process shows a high conversion efficiency compared with anomalous dispersion regime, which can guide and promote comb formation in materials with normal dispersion. As the comb spectra cover the mid-infrared wavelength range, they can find applications in comb-based radiofrequency photonic filters and mid-infrared spectroscopy.

Program-controlled single soliton microcomb source

Soliton microcombs(SMCs)are spontaneously formed in a coherently pumped high-quality microresonator,which provides a new tool for use as an on-chip frequency comb for applications of high-precision metrology and spectroscopy.However,generation of SMCs seriously relies on advanced experimental techniques from professional scientists.Here,we experimentally demonstrate a program-controlled single SMC source where the intracavity thermal effect is timely balanced using an auxiliary laser during single SMC generation.The microcomb power is adopted as the criteria for microcomb states discrimination and a forward and backward thermal tuning technique is employed for the deterministic single SMC generation.Further,based on a closed-loop control system,the repetition rate stability of the SMC source improved more than 20 times and the pump frequency can be continuously tuned by simply changing the operation temperature.The reliability of the SMC source is verified by consecutive 200 generation trials and maintaining over 10 h.We believe the proposed SMC source will have significant promising influences in future SMC-based application development.

Numerical simulation and temporal characterization of dual-pumped microringresonator-based optical frequency combs

Dual-pumped microring-resonator-based optical frequency combs(OFCs) and their temporal characteristics are numerically investigated and experimentally explored. The calculation results obtained by solving the driven and damped nonlinear Schr?dinger equation indicate that an ultralow coupled pump power is required to excite the primary comb modes through a non-degenerate four-wave-mixing(FWM) process and, when the pump power is boosted, both the comb mode intensities and spectral bandwidths increase. At low pump powers, the field intensity profile exhibits a cosine variation manner with frequency equal to the separation of the two pumps, while a roll Turing pattern is formed resulting from the increased comb mode intensities and spectral bandwidths at high pump powers. Meanwhile, we found that the power difference between the two pump fields can be transferred to the newly generated comb modes, which are located on both sides of the pump modes, through a cascaded FWM process. Experimentally, the dual-pumped OFCs were realized by coupling two self-oscillating pump fields into a microring resonator. The numerically calculated comb spectrum is verified by generating an OFC with 2.0 THz mode spacing over 160 nm bandwidth. In addition, the formation of a roll Turing pattern at high pump powers is inferred from the measured autocorrelation trace of a 10 free spectral range(FSR) OFC. The experimental observations accord well with the numerical predictions. Due to their large and tunable mode spacing, robustness,and flexibility, the proposed dual-pumped OFCs could find potential applications in a wide range of fields,including arbitrary optical waveform generation, high-capacity optical communications, and signal-processing systems.

Self-locked orthogonal polarized dual comb in a microresonator

Dual combs are an emerging tool to obtain unprecedented resolution, high sensitivity, ultrahigh accuracy, broabandwidth, and ultrafast data updating rate in the fields of molecular spectroscopy, optical metrology, as well optical frequency synthesis. The recent progress in chip-based microcombs has promoted the on-chip dual-commeasuring systems to a new phase attributed to the large frequency spacing and broad spectrum. In this paper, wdemonstrate proof-of-concept dual-comb generation with orthogonal polarization in a single microresonatthrough pumping both the transverse-electric(TE) and transverse-magnetic(TM) modes simultaneously. Ttwo orthogonal polarized pumps are self-oscillating in a fiber ring cavity. The generated dual comb exhibits ecellent stability due to the intrinsic feedback mechanism of the self-locked scheme. The repetition rate the two orthogonal combs is slightly different because of the mode spacing difference between the TE anTM modes. Such orthogonal polarized dual-combs could be a new comb source for out-of-lab applicatioin the fields of integrated spectroscopy, ranging measurement, optical frequency synthesis, and microwacomb generation.

Terabit FSO communication based on a soliton microcomb

Free-space optical(FSO)communication technology is a promising approach to establish a secure wireless link,which has the advantages of excellent directionality,large bandwidth,multiple services,low mass and less power requirements,and easy and fast deployments.Increasing the communication capacity is the perennial goal in both scientific and engineer communities.In this paper,we experimentally demonstrate a Tbit/s parallel FSO communication system using a soliton microcomb as a multiple wavelength laser source.Two communication terminals are installed in two buildings with a straight-line distance of~1 km.102 comb lines are modulated by10 Gbit/s differential phase-shift keying signals and demodulated using a delay-line interferometer.When the transmitted optical power is amplified to 19.8 dBm,42 optical channels have optical signal-to-noise ratios higher than 27 dB and bit error rates less than 1×10^(-9).Our experiment shows the feasibility of a wavelength-division multiplexing FSO communication system which suits the ultra-high-speed wireless transmission application scenarios in future satellite-based communications,disaster recovery,defense,last mile problems in networks and remote sensing,and so on.

基于板-梁理论的双轴对称哑铃形钢管混凝土拱弯扭屈曲理论研究

现有的理论公式只适用于单一材料构件,无法使用现有的稳定理论解决由不同材料组成的构件,为此,张文福教授在2014年独立提出一种可解决薄壁构件组合扭转和弯扭屈曲的新工程理论,该理论主要采用三种基本假设:刚周边假设、板变形假设、梁变形假设。与传统的Vlasov理论不同,板-梁理论中纵向位移、线性和非线性应变、应变能均可借鉴成熟的Kirchhoff薄板理论和Euler梁理论推导得到,不仅可以解决翘曲无法考虑钢和混凝土不同材料影响的问题,还可以避免假设翘曲函数的随意性带来的争议。为了描述方便,板梁理论中引入了两套坐标系,分别为整体坐标系xyz和局部坐标系nsz,这两套坐标系与Vlasov的坐标类似,均满足右手螺旋法则。整体坐标系的原点与截面形心重合,x、y轴分别为截面的主轴。与Vlasov的曲线坐标系不同,局部坐标系nsz为直角坐标系。原点与每个板件自身的形心重合,s轴与板件的中面重合,n轴与板件中面的法线重合。由n轴转向s轴符合右手螺旋法则,且拇指应该与z轴正方向一致。基于板-梁理论推导双轴对称哑铃形钢管混凝土的截面特性,根据相关假设,建立发生弯扭屈曲的位移场、应变场,推导出总应变能和总初应力势能,进而得出双轴对称哑铃形钢管混凝土截面的抗弯刚度、翘曲刚度和自由扭转刚度,通过算例和有限元分析验证理论公式的正确性。

Scanning dual-microcomb spectroscopy

Dual-comb spectroscopy(DCS) is a powerful tool in molecular spectroscopy benefiting from the advantages of high resolution and short measurement time. The recently developed soliton microcomb(SMC) can potentially transfer the dual-comb method to an on-chip platform. In this paper, we demonstrate DCS using two frequency scanning SMCs, termed scanning dual-microcomb spectroscopy(SDMCS). The two SMCs are generated by an auxiliary-assisted thermal balance scheme, and the pump laser frequency sweeps over one free spectral range of the microresonator(~49 GHz) using a feedback control system. The proposed SDMCS has a spectral resolution of 12.5 MHz, which is determined by the minimum sweeping step of the pump laser. Using this SDMCS system, we perform three types of gas molecule absorption spectroscopy recognition and gas concentration detection.This study paves the way for integrated DCS with a high signal-to-noise ratio, high spectral resolution, and fast acquisition rate.

Ultra-high-linearity integrated lithium niobate electro-optic modulators

Integrated lithium niobate(LN)photonics is a promising platform for future chip-scale microwave photonics systems owing to its unique electro-optic properties,low optical loss,and excellent scalability.A key enabler for such systems is a highly linear electro-optic modulator that could faithfully convert analog electrical signals into optical signals.In this work,we demonstrate a monolithic integrated LN modulator with an ultra-high spurious-free dynamic range(SFDR)of 120.04 dB·Hz^(4/5)at 1 GHz,using a ring-assisted Mach–Zehnder interferometer configuration.The excellent synergy between the intrinsically linear electro-optic response of LN and an optimized linearization strategy allows us to fully suppress the cubic terms of third-order intermodulation distortions(IMD3)without active feedback controls,leading to∼20 dB improvement over previous results in the thin-film LN platform.Our ultra-high-linearity LN modulators could become a core building block for future large-scale functional microwave photonic integrated circuits by further integration with other high-performance components like low-loss delay lines,tunable filters,and phase shifters available on the LN platform.