Handgrip strength and the risk of major depressive disorder:a two-sample Mendelian randomisation study

Background Major depressive disorder(MDD)is a common psychiatric disease and a leading cause of disability worldwide.Handgrip strength(HGS)as an objective physical fitness test is a practical index for identifying many diseases.Previous studies drew different conclusions about the relationship between HGS and MDD.Aims We aim to explore whether HGS has an effect on the risk of MDD.Methods HGS-related single-nucleotide polymorphisms identified by a genome-wide association study were used as instrumental variables in this Mendelian randomisation(MR)study.Summary data on MDD were obtained from the Psychiatric Genomics Consortium.Four methods were applied,including inverse variance weighted(IVW),MR Egger,weighted median and weighted mode.Additional sensitivity analyses,including leave-one-out,heterogeneity test,pleiotropy test and confounders identification,were conducted to test the robustness of our results.Results Each 1 kg increase in left HGS is associated with a 21.95%reduction in the risk of MDD(OR_(IVW)=0.781,95%CI:0.650 to 0.937,p=0.009),while no significant correlation exists in the estimation of right HGS(p=0.146).Sensitivity analyses demonstrated statistical significance(β_(IVW)=−0.195,p=0.023)after excluding some genetic loci that cause pleiotropy.Conclusions Increased left HGS is associated with a reduced risk of MDD.In the future,it may be used as an index for the clinical screening,observation and treatment of MDD.

6G无线空口传输技术研究进展与展望

自20世纪80年代以来,移动通信已彻底改变世界,对人们的生活产生了深远影响.在5G成功商用的今天,人们又开始思考6G会是什么样子.作为下一代移动通信系统,6G不仅在频谱效率、时延、可靠性等通信KPI指标上提出了更高的要求,其内涵也将涉及人工智能、感知等新元素,远超传统意义上移动通信的范畴.为了实现6G愿景,迫切需要业界研究与之相适应的先进无线技术方案.本文重点介绍了6G无线空口多个研究方向的技术趋势和进展,包括信道编码技术、多址和波形技术、智能超表面技术、智能MIMO(multiple input multiple output)技术等,提出并初步验证了一系列创新技术点,如便车码、格码多址等.这些创新技术的提出,对6G愿景和KPI指标的实现起到有力的支撑作用.

Advances in lithium niobate photonics:development status and perspectives

Lithium niobate(LN)has experienced significant developments during past decades due to its versatile properties,especially its large electro-optic(EO)coefficient.For example,bulk LN-based modulators with high speeds and a superior linearity are widely used in typical fiber-optic communication systems.However,with everincreasing demands for signal transmission capacity,the high power and large size of bulk LN-based devices pose great challenges,especially when one of its counterparts,integrated silicon photonics,has experienced dramatic developments in recent decades.Not long ago,high-quality thin-film LN on insulator(LNOI)became commercially available,which has paved the way for integrated LN photonics and opened a hot research area of LN photonics devices.LNOI allows a large refractive index contrast,thus light can be confined within a more compact structure.Together with other properties of LN,such as nonlinear/acousto-optic/pyroelectric effects,various kinds of high-performance integrated LN devices can be demonstrated.A comprehensive summary of advances in LN photonics is provided.As LN photonics has experienced several decades of development,our review includes some of the typical bulk LN devices as well as recently developed thin film LN devices.In this way,readers may be inspired by a complete picture of the evolution of this technology.We first introduce the basic material properties of LN and several key processing technologies for fabricating photonics devices.After that,various kinds of functional devices based on different effects are summarized.Finally,we give a short summary and perspective of LN photonics.We hope this review can give readers more insight into recent advances in LN photonics and contribute to the further development of LN related research.

Silicon substrate-integrated hollow waveguide for miniaturized optical gas sensing

Gas sensors have a wide variety of applications.Among various existing gas sensing technologies,optical gas sensors have outstanding advantages.The development of the Internet of Things and consumer electronics has put stringent requirements on miniaturized gas sensing technology.Here,we demonstrate a chip-scale silicon substrate-integrated hollow waveguide(Si-iHWG) to serve as an optical channel and gas cell in an optical gas sensor.It is fabricated through silicon wafer etching and wafer bonding.The Si-i HWG chip is further assembled with an off-chip light source and detector to build a fully functional compact nondispersive infrared(NDIR) CO_(2) sensor.The chip size is 10 mm × 9 mm,and the dimension of the sensor excluding the microcontroller board is 50 mm × 25 mm × 16 mm.This chip solution with compactness,versatility,robustness,and low cost provides a cost-effective platform for miniaturized optical sensing applications ranging from air quality monitoring to con-sumer electronics.

Micro-and nano-fiber probes for optical sensing,imaging,and stimulation in biomedical applications

The flexibile nature of optical fiber enables it to offer remote-access capabilities,which could be used in many biomedical applications.This review focuses on different micro-and nano-structured fiber probes for applications in biosensing,imaging,and stimulations.The modifications to fiber could extend design freedom from waveguide optimization to functional material integration.Fiber probes with optimized waveguide structures or integrated functional materials could achieve enhanced optical mode interaction with biosamples,and hence obtain ultrasensitive biosensors with a remarkably low limit of detection.Furthermore,bioimaging with a high spatial resolution can be obtained by engineering dispersion and nonlinearity of light propagation in the fiber core or designing a metal-coated tapered fiber tip with a sub-wavelength aperture.Flat metasurfaces can be assembled on a fiber tip to achieve a large depth of focus and remove aberrations.Fiber is also a compact solution to realize the precise delivery of light for in vivo applications,such as deep brain stimulation.The optical beam size,shape,and direction could be steered by the probe parameters.Micro-and nano-technologies integrated with fiber contribute to various approaches to further improve detection limit,sensitivity,optical resolution,imaging depth,and stimulation precision.

Octave-spanning coherent supercontinuum generation in silicon on insulator from 1.06μm to beyond 2.4μm

Efficient complementary metal-oxide semiconductor-based nonlinear optical devices in the near-infrared are in strong demand.Due to two-photon absorption in silicon,however,much nonlinear research is shifting towards unconventional photonics platforms.In this work,we demonstrate the generation of an octave-spanning coherent supercontinuum in a silicon waveguide covering the spectral region from the near-to shortwave-infrared.With input pulses of 18 pJ in energy,the generated signal spans the wavelength range from the edge of the silicon transmission window,approximately 1.06 to beyond 2.4μm,with a−20 dB bandwidth covering 1.124–2.4μm.An octave-spanning supercontinuum was also observed at the energy levels as low as 4 pJ(−35 dB bandwidth).We also measured the coherence over an octave,obtaining|g_()12^(1)(λ)>90%,in good agreement with the simulations.In addition,we demonstrate optimization of the third-order dispersion of the waveguide to strengthen the dispersive wave and discuss the advantage of having a soliton at the long wavelength edge of an octave-spanning signal for nonlinear applications.This research paves the way for applications,such as chip-scale precision spectroscopy,optical coherence tomography,optical frequency metrology,frequency synthesis and wide-band wavelength division multiplexing in the telecom window.

Metasurface-based subtractive color filter fabricated on a 12-inch glass wafer using a CMOS platform

Optical color filters are widely applied in many areas including display,imaging,sensing,holography,energy harvest,and measurement.Traditional dye-based color filters have drawbacks such as environmental hazards and instability under high temperature and ultraviolet radiation.With advances in nanotechnology,structural color filters,which are based on the interaction of light with designed nanostructures,are able to overcome the drawbacks.Also,it is possible to fabricate structural color filters using standard complementary metal-oxide-semiconductor(CMOS)fabrication facilities with low cost and high volume.In this work,metasurface-based subtractive color filters(SCFs)are demonstrated on 12-inch(300-mm)glass wafers using a CMOS-compatible fabrication process.In order to make the transmissive-type SCF on a transparent glass wafer,an in-house developed layer transfer process is used to solve the glass wafer handling issue in fabrication tools.Three different heights of embedded silicon nanopillars(110,170,and 230 nm)are found to support magnetic dipole resonances.With pillar height and pitch variation,SCFs with different displayed colors are achieved.Based on the resonance wavelength,the displayed color of the metasurface is verified within the red-yellow-blue color wheel.The simulation and measurement results are compared and discussed.The work provides an alternative design for high efficiency color filters on a CMOS-compatible platform,and paves the way towards mass-producible large-area metasurfaces.

Optical frequency synthesizer with an integrated erbium tunable laser

Optical frequency synthesizers have widespread applications in optical spectroscopy,frequency metrology,and many other fields.However,their applicability is currently limited by size,cost,and power consumption.Silicon photonics technology,which is compatible with complementary-metal-oxide-semiconductor fabrication processes,provides a low-cost,compact size,lightweight,and low-power-consumption solution.In this work,we demonstrate an optical frequency synthesizer using a fully integrated silicon-based tunable laser.The synthesizer can be self-calibrated by tuning the repetition rate of the internal mode-locked laser.A 20 nm tuning range from 1544 to 1564 nm is achieved with~10−13 frequency instability at 10 s averaging time.Its flexibility and fast reconfigurability are also demonstrated by fine tuning the synthesizer and generating arbitrary specified patterns over time-frequency coordinates.This work promotes the frequency stability of silicon-based integrated tunable lasers and paves the way toward chip-scale lowcost optical frequency synthesizers.