Impact of non-Gaussian noise on GMI and LDPC performance in neural network equalized systems.

In this Letter, the impact of non-Gaussian noise caused by a nonlinear equalizer on low-density parity-check code (LDPC) performance is investigated in a 25-km 50-Gb/s pulse amplitude modulation4 (PAM4) direct detection system. The lookup table (LUT)-based log-likelihood ratio (LLR) calculation method is proposed to enhance the LDPC performance for the non-Gaussian noise case. Compared to the conventional LLR calculation method based on Gaussian distribution, the proposed method can improve 0.6-dB sensitivity in artificial neural network (ANN) equalizer systems. In addition, the conventional generalized mutual information (GMI) is proven to be an imperfect predictor of LDPC performance after nonlinear equalizers, such as decision feedback equalization (DFE) and ANN equalizer.

Phase noise-induced interference for coherently detected OTDR systems.

The phase noise-induced interference (PNII) in coherently detected OTDR systems is investigated. A close-form relationship between signal to (interference) noise ratio (SNR) and laser linewidth is derived for the first time, to the best of our knowledge, and numerical simulations are conducted to verify the theoretical results. Additionally, the proportion of noise composition of PNII is studied. It is shown that the amplitude noise accounts for one-third of the total interference. This analytical form of PNII will assist in understanding the COTDR system that utilizes the full field of information (rather than intensity alone) at the receiver and, more importantly, provides a crucial guideline for designing high-performance and cost-effective COTDR systems in various applications.

Efficient dynamic tunable metasurface based on Ge2Sb2Te5 in the near infrared band.

For effective wavefront management in the optical infrared range, dynamic all-dielectric metasurfaces, always based on phase transition materials, particularly G e 2 S b 2 T e 5 (GST), can be used. In this paper, we propose a GST-based tunable metasurface by structuring the phase-change material GST. We confirm that the nanopillar we designed has high transmittance in the wavelength band around 1550 nm and can fully cover the 0∼2π phase. Based on these characteristics, we can achieve beam steering and a focusing effect in amorphous phase by elaborately arranging GST nanopillars, while the aforementioned optical phenomena disappear in crystalline phase. Additionally, by arranging the array of vortex phases, we also realize switching the perfect composite vortex beam (PCVB) when changing the crystal state of GST, and simulate the generation of PCVB with different topological charges and sizes in amorphous phase. We believe that our research results can serve as a reference for multifunctional optical surfaces, dynamic optical control, optical communication, and information processing.

Adjustable Trifunctional Mid-Infrared Metamaterial Absorber Based on Phase Transition Material VO2.

In this paper, we demonstrate an adjustable trifunctional absorber that can achieve the conversion of broadband, narrowband and superimposed absorption based on the phase transition material vanadium dioxide (VO2) in the mid-infrared domain. The absorber can achieve the switching of multiple absorption modes by modulating the temperature to regulate the conductivity of VO2. When the VO2 film is adjusted to the metallic state, the absorber serves as a bidirectional perfect absorber with switching capability of wideband and narrowband absorption. The superposed absorptance can be generated while the VO2 layer is converted to the insulating state. Then, we introduced the impedance matching principle to explain the inner mechanism of the absorber. Our designed metamaterial system with a phase transition material is promising for sensing, radiation thermometer and switching devices.

Applying deep learning-based regional feature recognition from macro-scale image to assist energy saving and emission reduction in industrial energy systems.

INTRODUCTION: Image recognition technology has immense potential to be applied in industrial energy systems for energy conservation. However, the low recognition accuracy and generalization ability under actual operation conditions limit its commercial application. OBJECTIVES: To improve the recognition accuracy and generalization ability, a novel image recognition method integrating deep learning and domain knowledge was applied to assist energy saving and emission reduction for industrial energy systems. METHODS: As a typical industrial scenario, the defrosting control in the refrigeration system was selected as the specific optimization object. By combining deep learning algorithm with domain knowledge, a residual-based convolutional neural network model (RCNN) was proposed specifically for frosty state recognition, which features the residual input and average pooling output. Based on the real-time recognition of frosty levels, a defrosting control optimization method was proposed to initiate and terminate the defrosting operation on demand. RESULTS: By combining the advanced image recognition technique with specific energy domain knowledge, the proposed RCNN enables both high recognition accuracy and strong generalization ability. The recognition accuracy of RCNN reached 95.06% for the trained objects and 93.67% for non-trained objects while that of only 75.86% for the conventional CNN. By adopting the presented system optimization method assisted by RCNN, the defrosting frequency, accumulated time and energy consumption were 53.8%, 57.02% and 34.5% less than the original control method. Furthermore, the environmental and cost analysis illustrated that the annual reduction in CO2 emissions is 2145.21 to 3412.84 kg and the payback time was less than 2.5 years which was far below the service life. CONCLUSION: The technical feasibility and significant energy-saving benefits of deep learning-based image recognition method were demonstrated through the field experiment. Our study shows the great application potential of image recognition technology and promotes carbon neutrality in industrial energy systems.

Adjustable converter of bound state in the continuum basing on metal-graphene hybrid metasurfaces.

The bound state in the continuum (BIC) is widely applied to metamaterial study in order to obtain robust resonance and high quality (Q) factor. In this paper, we propose a metallic metasurface structure that can support double types of BICs, and acquire quasi-BIC state by restructuring each type with a specific approach. Electric field distribution is investigated to explore the physic mechanism behind the evolution of BICs. Moreover, we substitute structured graphene with corresponding metal counterparts. The promoted design is able to switch freely between BIC and quasi-BIC state even after the fabrication, as the graphene would convert from semiconductor-like to metal-like when increasing the Fermi level. Further exploration on electric field distribution demonstrates the metallicity difference between graphene and gold, which leads to the exotic phenomenon emerge on the proposed metal-graphene structure. Finally, the proposed metal-graphene structure is applied to a digital coding display through Fermi level regulating. Therefore, our work provides deep insights to the BIC metasurface investigation, and introduces a desirable improvement for current BIC metasurface design to achieve the free conversion between BIC and quasi-BIC states.

Sports Injury Identification Method Based on Machine Learning Model.

With the increasingly fierce competition in international competitive sports, the momentum of special training has increased. Sports injuries are becoming more and more serious, which restricts the further improvement of the level of athletes. How to solve the problem of prevention, treatment, and rehabilitation of sports injuries, so as to ensure the normal training and competition of athletes, is an important part of sports work. Machine learning can solve large-scale data problems that cannot be solved by human beings at present and has strong self-learning ability, self-optimization ability, and strong generalization ability. Therefore, the purpose of this study is to understand the characteristics of rhythmic gymnastics injuries and analyze their causes by investigating the injury status of elite rhythmic gymnasts. According to the characteristics of the project, the injury characteristics of the athletes themselves, and other factors, using scientific qualitative and quantitative indicators, the injury risk of key athletes in rhythmic gymnastics was evaluated. It also provides theoretical and practical references for preventing sports injuries, formulating and implementing sports injury rehabilitation programs. The experimental results show that the female vaulting risk in the five risk categories fluctuates from 179.62 to 365.8, ranking the first in the risk of acute sports injury.

Multibit NOT logic gate enabled by a function programmable optical waveguide.

Multibit logic gates are of great importance in optical switching and photonic computing. A 4-bit parallel optical NOT logic gate is demonstrated by an optical switching/computing engine based on a multimode waveguide. The multimode interference (MMI) patterns can be altered by thermal electrodes because the number of guided modes, their profiles, and propagation constants can all be altered via the thermo-optic effect. Instead of conventional forward design based on time-consuming simulations, the proposed engine can update the thermal electrodes automatically and monitor the change of the interference in a synchronized and rapid way until the desired function is reached, all experimentally. We name the system "function programmable waveguide engine" (FPWE). As opposed to solutions where the phase or amplitude of light is taken as the signal, the input stays in the electronic domain, and the output is converted into optical intensity variations, calculated from a truth table. This simple, low-cost yet powerful engine may lead to the development of a new set of devices for on-chip photonic computing and signal switching.

Material contact sensor with 3D coupled waveguides.

An evanescent field sensor to identify materials by contact has been demonstrated using a 3D coupled waveguide array. The array is formed by imbedding layered silicon nitride stripes as waveguide cores in polymer cladding and the top cladding layer is etched open for material sensing. When objects with different refractive indexes are placed on the surface of the sensor, the evanescent field is disturbed and both the local modal distribution and the coupling condition with the connecting segments are altered, leading to different interference patterns when light from the output facet is captured and focused onto a camera. We have chosen four conventional materials for test: polymer, silicon, aluminum and silver. The sensor is able to tell them apart with distinctive patterns. In addition, the sensor can identify the location of the contact, once the material is recognized. This simple and low-cost device, supported by the recent development of image recognition technology, may open up new possibilities in chip-based sensing applications.

Multiport all-logic optical switch based on thermally altered light paths in a multimode waveguide.

A generic multiport optical switch capable of generating all-logic outputs is demonstrated by altering the mode profiles and propagation characteristics in a multimode waveguide through a combination of microheaters. The principles and design rules are introduced. As proof of concept, a 3-bit all-logic switch is fabricated on a polymer waveguide platform. The experimental results are in good agreement with the simulations based on a heat solver and the eigenmode expansion method. The device shows polarization insensitive and colorless operation from 1520 to 1600 nm with an extinction ratio between "On" and "Off" states larger than 11.9 dB in all cases. The maximum heat power is 43.9 mW (for (1, 0, 0) state). The simple, compact, and easily scalable device can be used to construct 1×N and M×N switch networks, showing promising applications in on-chip photonic signal processing and computation.

3D integrated wavelength demultiplexer based on a square-core fiber and dual-layer arrayed waveguide gratings.

We present a 3D integrated wavelength demultiplexer using a square-core fiber (SCF) and matched dual-layer arrayed waveguide gratings (AWGs). The SCF works as a 3D fiber multimode interference device, which splits the input light into symmetric four spots. The spots are then coupled to a pitch-matched 4-waveguide network, each connecting an AWG. Interface waveguides are designed to improve the coupling efficiency between the SCF and the dual-layer chip. The four AWGs are designed with different central wavelengths and a large free spectral range (FSR) of 120 nm. To reach a small and uniform insertion loss among different channels, only the central channels of each AWG are used for demultiplexing. The device is fabricated on a polymer platform. The upper and lower layers of the chip are fabricated using the same photolithography mask but rotated 180° so that 4 different AWG designs can be mapped to a single chip. The measured transmission spectra of the four AWGs cover a bandwidth of 112 nm. The insertion loss variation is smaller than 1.4 dB. The designed device can find applications in fiber optic sensing, communication, and astronomy.

An unexpected INAD PDZ tandem-mediated plcß binding in Drosophila photo receptors.

INAD assembles key enzymes of the Drosophila compound eye photo-transduction pathway into a supramolecular complex, supporting efficient and fast light signaling. However, the molecular mechanism that governs the interaction between INAD and NORPA (phospholipase Cß, PLCß), a key step for the fast kinetics of the light signaling, is not known. Here, we show that the NORPA C-terminal coiled-coil domain and PDZ-binding motif (CC-PBM) synergistically bind to INAD PDZ45 tandem with an unexpected mode and unprecedented high affinity. Guided by the structure of the INAD-NORPA complex, we discover that INADL is probably a mammalian counterpart of INAD. The INADL PDZ89 tandem specifically binds to PLCß4 with a mode that is strikingly similar to that of the INAD-NORPA complex, as revealed by the structure of the INADL PDZ89-PLCß4 CC-PBM complex. Therefore, our study suggests that the highly specific PDZ tandem - PLCß interactions are an evolutionarily conserved mechanism in PLCß signaling in the animal kingdom.

Thermal stability of optical fiber metal organic framework based on graphene oxide and nickel and its hydrogen adsorption application.

The electrochemistry (EC) method was used to synthesize graphene oxide-nickel (GO-Ni) metal organic framework (MOF) that has the thickness of µm-level. The MOF's thermal stability and hydrogen adsorption and desorption capacity were measured by using an optical fiber Mach-Zehnder interferometer (MZI) sensor. This MZI was fabricated by core-offset fusion splicing one section of single mode fiber (SMF) between two SMFs. Experimental results showed that the GO-Ni MOF could be stabilized, even as the environmental temperature reached 125 °C. The MOF showed good hydrogen adsorption ability for the the MOF and hydrogen molecules's interactions.

A Novel Fiber Optic Surface Plasmon Resonance Biosensors with Special Boronic Acid Derivative to Detect Glycoprotein.

We proposed and demonstrated a novel tilted fiber Bragg grating (TFBG)-based surface plasmon resonance (SPR) label-free biosensor via a special boronic acid derivative to detect glycoprotein with high sensitivity and selectivity. TFBG, as an effective sensing element for optical sensing in near-infrared wavelengths, possess the unique capability of easily exciting the SPR effect on fiber surface which coated with a nano-scale metal layer. SPR properties can be accurately detected by measuring the variation of transmitted spectra at optical communication wavelengths. In our experiment, a 10° TFBG coated with a 50 nm gold film was manufactured to stimulate SPR on a sensor surface. To detect glycoprotein selectively, the sensor was immobilized using designed phenylboronic acid as the recognition molecule, which can covalently bond with 1,2- or 1,3-diols to form five- or six-membered cyclic complexes for attaching diol-containing biomolecules and proteins. The phenylboronic acid was synthetized with long alkyl groups offering more flexible space, which was able to improve the capability of binding glycoprotein. The proposed TFBG-SPR sensors exhibit good selectivity and repeatability with a protein concentration sensitivity up to 2.867 dB/ (mg/mL) and a limit of detection (LOD) of 15.56 nM.

A Novel Low-Power-Consumption All-Fiber-Optic Anemometer with Simple System Design.

A compact and low-power consuming fiber-optic anemometer based on single-walled carbon nanotubes (SWCNTs) coated tilted fiber Bragg grating (TFBG) is presented. TFBG as a near infrared in-fiber sensing element is able to excite a number of cladding modes and radiation modes in the fiber and effectively couple light in the core to interact with the fiber surrounding mediums. It is an ideal in-fiber device used in a fiber hot-wire anemometer (HWA) as both coupling and sensing elements to simplify the sensing head structure. The fabricated TFBG was immobilized with an SWCNT film on the fiber surface. SWCNTs, a kind of innovative nanomaterial, were utilized as light-heat conversion medium instead of traditional metallic materials, due to its excellent infrared light absorption ability and competitive thermal conductivity. When the SWCNT film strongly absorbs the light in the fiber, the sensor head can be heated and form a "hot wire". As the sensor is put into wind field, the wind will take away the heat on the sensor resulting in a temperature variation that is then accurately measured by the TFBG. Benefited from the high coupling and absorption efficiency, the heating and sensing light source was shared with only one broadband light source (BBS) without any extra pumping laser complicating the system. This not only significantly reduces power consumption, but also simplifies the whole sensing system with lower cost. In experiments, the key parameters of the sensor, such as the film thickness and the inherent angle of the TFBG, were fully investigated. It was demonstrated that, under a very low BBS input power of 9.87 mW, a 0.100 nm wavelength response can still be detected as the wind speed changed from 0 to 2 m/s. In addition, the sensitivity was found to be -0.0346 nm/(m/s) under the wind speed of 1 m/s. The proposed simple and low-power-consumption wind speed sensing system exhibits promising potential for future long-term remote monitoring and on-chip sensing in practical applications.

Biochemical and structural characterization of MUPP1-PDZ4 domain from Mus musculus.

Specific protein-protein interactions are important for biological signal transduction. The postsynaptic density-95, disc-large, and zonulin-1 (PDZ) domain is one of the most abundant protein interaction modules. Multi-PDZ-domain protein 1 (MUPP1), as a scaffold protein, contains 13 PDZ domains and plays an important role in cytoskeletal organization, cell polarity, and cell proliferation. The study on PDZ domain of MUPP1 helps to understand the mechanisms and functions of MUPP1. In the present study, the fourth PDZ domain of MUPP1 (MUPP1-PDZ4) from Mus musculus was cloned, expressed, purified, and characterized. The MUPP1-PDZ4 domain was subcloned into a pET-vector and expressed in Escherichia coli. Affinity chromatography and size-exclusion chromatography were used to purify the protein. MUPP1-PDZ4 protein was a monomer with a molar mass of 16.4 kDa in solution and had a melting point of 60.3°C. Using the sitting-drop vapor-diffusion method, MUPP1-PDZ4 protein crystals were obtained in a solution (pH 7.0) containing 2% (v/v) polyethylene glycol 400, 0.1 M imidazole, and 24% (w/v) polyethylene glycol monoethyl ether 5000. Finally, the crystal was diffracted with 1.6 Å resolution. The crystal structure showed that MUPP1-PDZ4 domain contained three α-helices and six ß-strands in the core. The GLGI motif, L562/A564 on the ß-strand B, and H605/V608/L612 on the α-helix B formed a PDZ binding pocket which could bind to the C-terminal of the binding partners. This biochemical and structural information will provide insights into how PDZ binds to its target peptide and the theoretical foundation for the function of MUPP1.

A critical role of Fas-associated protein with death domain phosphorylation in intracellular reactive oxygen species homeostasis and aging.

AIM: Reactive oxygen species (ROS) plays important roles in aging. However, the specific mechanisms for intracellular ROS accumulation, especially during aging, remain elusive. RESULTS: We have reported that Fas-associated protein with death domain (FADD) phosphorylation abolishes the recruitment of phosphatase type 2A C subunit (PP2Ac) to protein kinase C (PKC)ßII, which specifically regulates mitochondrial ROS generation by p66shc. Here, we have studied the role of FADD phosphorylation in an FADD constitutive-phosphorylation mutation (FADD-D) mouse model. In FADD-D mice, the constitutive FADD phosphorylation led to ROS accumulation (hydrogen peroxide [H2O2]), in a process that was dependent on PKCß and accompanied by increased PKCß and p66shc phosphorylation, impaired mitochondrial integrity, and enhanced sensitivity to oxidative stress-mediated apoptosis. Moreover, FADD-D mice exhibited premature aging-like phenotypes, including DNA damage, cellular senescence, and shortened lifespan. In addition, we demonstrate that FADD phosphorylation and the recruitment of PP2A and FADD to PKCß are induced responses to oxidative stress, and that the extent of FADD phosphorylation in wild-type mice was augmented during aging, accompanied by impairment of the interaction between PKCß and PP2A. INNOVATION: The present study first addresses the role of FADD phosphorylation in aging through controlling mitochondrial ROS specifically generated by PKCß. CONCLUSION: These data identify that FADD phosphorylation is critical for the PKCß-p66shc signaling route to generate H2O2 and to implicate enhanced FADD phosphorylation as a primary cause of ROS accumulation during aging.

Self-renewal and differentiation of muscle satellite cells are regulated by the Fas-associated death domain.

Making the decision between self-renewal and differentiation of adult stem cells is critical for tissue repair and homeostasis. Here we show that the apoptotic adaptor Fas-associated death domain (FADD) regulates the fate decisions of muscle satellite cells (SCs). FADD phosphorylation was specifically induced in cycling SCs, which was high in metaphase and declined in later anaphase. Furthermore, phosphorylated FADD at Ser-191 accumulated in the uncommitted cycling SCs and was asymmetrically localized in the self-renewing daughter SCs. SCs containing a phosphoryl-mimicking mutation at Ser-191 of FADD (FADD-D) expressed higher levels of stem-like markers and reduced commitment-associated markers. Moreover, a phosphoryl-mimicking mutation at Ser-191 of FADD suppressed SC activation and differentiation, which promoted the cycling SCs into a reversible quiescent state. Therefore, these data indicate that FADD regulates the fate determination of cycling SCs.