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Different from the traditional healthcare field, Medical Cyber Physical Systems (MCPS) rely more on wireless wearable devices and medical applications to provide better medical services. The secure storage and sharing of medical data are facing great challenges. Blockchain technology with decentralization, security, credibility and tamper-proof is an effective way to solve this problem. However, capacity limitation is one of the main reasons affecting the improvement of blockchain performance. Certificateless aggregation signature schemes can greatly tackle the difficulty of blockchain expansion. In this paper, we describe a two-layer system model in which medical records are stored off-blockchain and shared on-blockchain. Furthermore, a multi-trapdoor hash function is proposed. Based on the proposed multi-trapdoor hash function, we present a certificateless aggregate signature scheme for blockchain-based MCPS. The purpose is to realize the authentication of related medical staffs, medical equipment, and medical apps, ensure the integrity of medical records, and support the secure storage and sharing of medical information. The proposed scheme is highly computationally efficient because it does not use bilinear maps and exponential operations. Many certificateless aggregate signature schemes without bilinear maps in Internet of things (IoT) have been proposed in recent years, but they are not applied to the medical field, and they do not consider the security requirements of medical data. The proposed scheme in this paper has high computing and storage efficiency, while meeting the security requirements in MCPS.

In this paper, a latest theoretical model for the performance optimization of the broad-sense quantum-well superluminescent diodes (SLDs) based on the concept of energy level divergence (ELD) is presented. The simulation results on the performance of such a kind of devices with GaAs/AlGaAs potential-well structures and ignorable residual facet-reflections show that the ELD concept is truly valid and necessary to be considered in the modelling. It is also found that, for a fixed output power, both the spectral ripple coefficient and the spectral bandwidth decrease monotonically as the well-thickness increases. Moreover, the simulation results are in a pretty good approximation with the experimental ones. Typically, for a 3 mm long and 10 μm wide (referring to the active-region width) device emitting a fixed power of 25 mW and being required to have a ripple-coefficient not larger than 5%, the experimentally determined optimum well-thickness is 90 nm and the simulation one is 87 nm. And, the corresponding spectral bandwidths are 15 nm and 14.8 nm, respectively. It is believed that such a theoretical model could be further improved and eventually worthy for practical use.

In the domain of optical fiber distributed acoustic sensing, the persistent challenge of extending sensing distances while concurrently improving spatial resolution and frequency response range has been a complex endeavor. The amalgamation of pulse compression and frequency division multiplexing methodologies has provided certain advantages. Nevertheless, this approach is accompanied by the drawback of significant bandwidth utilization and amplified hardware investments. This study introduces an innovative distributed optical fiber acoustic sensing system aimed at optimizing the efficient utilization of spectral resources by combining compressed pulses and frequency division multiplexing. The system continuously injects non-linear frequency modulation detection pulses spanning various frequency ranges. The incorporation of non-uniform frequency division multiplexing augments the vibration frequency response spectrum. Additionally, nonlinear frequency modulation adeptly reduces crosstalk and enhances sidelobe suppression, all while maintaining a favorable signal-to-noise ratio. Consequently, this methodology substantially advances the spatial resolution of the sensing system. Experimental validation encompassed the multiplexing of eight frequencies within a 120 MHz bandwidth. The results illustrate a spatial resolution of approximately 5 m and an expanded frequency response range extending from 1 to 20 kHz across a 16.3 km optical fiber. This achievement not only enhances spectral resource utilization but also reduces hardware costs, making the system even more suitable for practical engineering applications.

The Pancharatnam-Berry (PB) phase principle has been extensively utilized in the design of polarization-dependent, ultrathin, phase-gradient metasurfaces, where the PB phase shift is determined by twice the change in orientation angle of individual building blocks. Here, we reveal a topological transition in the phase-orientation dependence within a nonlocal bilayer metasurface, where a fourfold dependence emerges as the building blocks are tightly arranged. Additionally, we demonstrate that the Moiré pattern inherent to the bilayer metasurface provides a tunable mechanism for driving this topological transition, enabling the modulation of both deflection angle and topological charge of the transmitted field. Our findings not only offer a refined understanding of the PB phase principle in linear optical systems but also introduce twist angle as a novel degree of freedom for designing tunable PB phase devices.

Propagation properties of electromagnetic waves in an optical medium are mainly determined by the contour of equal-frequency states in k-space. In photonic Weyl media, the topological surface waves lead to a unique open arc of the equal-frequency contour, called the Fermi arc. However, for most realistic Weyl systems, the shape of Fermi arcs is fixed due to the constant impedance of the surrounding medium, making it difficult to manipulate the surface wave. Here we demonstrate that by adjusting the thickness of the air layer sandwiched between two photonic Weyl media, the shape of the Fermi arc can be continuously changed from convex to concave. Moreover, we show that the concave Fermi-arc waves can be used to achieve topologically protected electromagnetic pulling forces over a broad range of angles in the air layer. Our finding offers a generally applicable strategy to shape the Fermi arc in photonic Weyl media.The continuous evolution of the shape of the surface Fermi arc induces an electromagnetic pulling force that operates over a broad range of angles, effectively attracting a variety of small particles.

Deoxynivalenol (DON) poses significant risks to both human and animal health and severely disrupts the global grain trade due to its prevalence as a common contaminant in wheat grains. With rising public concern over food safety, finding effective and sustainable methods to reduce DON contamination becomes increasingly urgent. In our study, we found that methyl jasmonate (MeJA), a natural plant hormone, can effectively inhibit the vegetative growth of F. graminearum and significantly reduce its DON toxin production. To explore the underlying molecular mechanism, we identified the mutations in MeJA-tolerant mutants and revealed that MeJA effectively exerts its antifungal activities by inhibiting the cAMP-PKA signaling pathway in F. graminearum . Our work provides a promising natural solution to reduce DON toxin contamination in cereal grains, enhancing food safety while decreasing the reliance on chemical fungicides and their associated environmental impact.

An interesting phenomenon that the photocurrent (the difference between illumination and dark current) of a ZnO nanowire (NW) under a specified voltage increased as its length increased in a certain range was observed previously and it was supposed to be mainly due to a special mean free path effect (MFPE) which caused a special distribution of dark electron density along the length with two higher electron density regions near the two ends of the NW, respectively, and the lower one in the middle part. However, such an explanation would be unreasonable and the true reasons should be the growing-process caused variation of the oxygen adsorption capacity along the NW length and the length-dependent lifetime of photogenerated carriers. Based on this understanding, a theoretical model to properly explain this phenomenon is proposed and the calculation results are in good agreement with the experimental data. This work has introduced an improved insight into the theory of the length-dependent photoelectric property of ZnO NWs.

Dual-mode photodetectors (DmPDs) have attracted considerable interest due to their ability to integrate multiple functionalities into a single device. However, 2D material/InP heterostructures, which exhibit built-in electric fields and rapid response characteristics, have not yet been utilized in DmPDs. In this work, we fabricate a high-performance DmPD based on a graphene/InP Van der Waals heterostructure in a facile way, achieving a broadband response from ultraviolet-visible to near-infrared wavelengths. The device incorporates two top electrodes contacting monolayer chemical vapor deposition (CVD) graphene and a bottom electrode on the backside of an InP substrate. By flexibly switching among these three electrodes, the as-fabricated DmPD can operate in a self-powered photovoltaic mode for energy-efficient high-speed imaging or in a biased photoconductive mode for detecting weak light signals, fully demonstrating its multifunctional detection capabilities. Specifically, in the self-powered photovoltaic mode, the DmPD leverages the vertically configured Schottky junction to achieve an on/off ratio of 8 × 103, a responsivity of 49.2 mA/W, a detectivity of 4.09 × 1011 Jones, and an ultrafast response, with a rising time (τr) and falling time (τf) of 2.8/6.2 μs. In the photoconductive mode at a 1 V bias, the photogating effect enhances the responsivity to 162.5 A/W. This work advances the development of InP-based multifunctional optoelectronic devices.

The large amount of sampled data in coherent phase-sensitive optical time-domain reflectometry (Φ-OTDR) brings heavy data transmission, processing, and storage burdens. By using the comparator combined with undersampling, we achieve simultaneous reduction of sampling rate and sampling resolution in hardware, thus greatly decreasing the sampled data volume. But this way will inevitably cause the deterioration of detection signal-to-noise ratio (SNR) due to the quantization noise’s dramatic increase. To address this problem, denoising the demodulated phase signals using compressed sensing, which exploits the sparsity of spectrally sparse vibration, is proposed, thereby effectively enhancing the detection SNR. In experiments, the comparator with a sampling parameter of 62.5 MS/s and 1 bit successfully captures the 80 MHz beat signal, where the sampled data volume per second is only 7.45 MB. Then, when the piezoelectric transducer’s driving voltage is 1 Vpp, 300 mVpp, and 100 mVpp respectively, the SNRs of the reconstructed 200 Hz sinusoidal signals are respectively enhanced by 23.7 dB, 26.1 dB, and 28.7 dB by using compressed sensing. Moreover, multi-frequency vibrations can also be accurately reconstructed with a high SNR. Therefore, the proposed technique can effectively enhance the system’s performance while greatly reducing its hardware burden.

Background Studies on consistency among spirometry, impulse oscillometry (IOS), and histology for detecting small airway dysfunction (SAD) remain scarce. Considering invasiveness of lung histopathology, we aimed to compare spirometry and IOS with chest computed tomography (CT) for SAD detection, and evaluate clinical characteristics of subjects with SAD assessed by these three techniques. Methods We collected baseline data from the Early COPD (ECOPD) study. CT-defined SAD was defined as parametric response mapping quantifying SAD (PRM fSAD ) ≥ 15%. Spirometry-defined SAD was defined as at least two of maximal mid-expiratory flow (MMEF), forced expiratory flow 50% (FEF50), and forced expiratory flow 75% (FEF75) less than 65% of predicted. IOS-defined SAD was defined as peripheral airway resistance R5 − R20 > 0.07 kPa/L/s. The consistency of spirometry, IOS and CT for diagnosing SAD was assessed using Kappa coefficient. Correlations among the three techniques-measured small airway function parameters were assessed by Spearman correlation analysis. Results 2055 subjects were included in the final analysis. There was low agreement in SAD assessment between spirometry and CT (Kappa = 0.126, 95% confidence interval [CI]: 0.106 to 0.146, p  < 0.001), between IOS and CT (Kappa = 0.266, 95% CI: 0.219 to 0.313, p  < 0.001), as well as among spirometry, IOS, and CT (Kappa = 0.056, 95% CI: 0.029 to 0.082, p  < 0.001). The correlation was moderate (|r|: 0.5 to 0.7, p  < 0.05) between spirometry and CT-measured small airway function parameters, and weak (|r|< 0.4, p  < 0.05) between IOS and CT-measured small airway function parameters. Only spirometry-defined SAD group had more lower lung function (FEV 1 /FVC: adjusted difference=-10.7%, 95% CI: -13.5% to -7.8%, p  < 0.001) and increased airway wall thickness (Pi 10: adjusted difference = 0.3 mm, 95% CI: 0 to 0.6 mm, p  = 0.046) than only CT-defined SAD group. Only IOS-defined SAD group had better lung function (FEV 1 /FVC: adjusted difference = 3.9%, 95% CI: 1.9 to 5.8%, p  < 0.001), less emphysema (inspiratory LAA − 950 : adjusted difference=-2.1%, 95% CI:-3.1% to -1.1%, P  < 0.001; PRM Emph : adjusted difference=-2.3%, 95% CI: -3.2% to -1.4%, p  < 0.001), and thicker airway wall (Pi 10: adjusted difference = 0.2 mm, 95% CI: 0.1 mm to 0.4 mm, p  = 0.005) than only CT-defined SAD group. Conclusions There was low consistency in the assessment of SAD between spirometry and CT, between IOS and CT, as well as among spirometry, IOS, and CT. Clinical trial number Not applicable.