Denoised single-pixel imaging in a Fourier acquisition mode.

The degradation of imaging quality caused by environmental noise during Fourier single pixel imaging (FSPI) is a big problem. In this paper, we propose simple and efficient denoised single-pixel imaging schemes by using linear filters to reduce the impact. Two filters, such as an average filter and Gaussian filter, are employed, and their corresponding schemes are named SCH-A and SCH-G, respectively. The experimental and simulation results show that both schemes can effectively reduce the impact of environmental noise and have greater robustness in comparison with those using the deringing SPI and conventional SPI. Compared with SCH-A, the reconstructed image by SCH-G keeps more details and edges. With the increase of template size, SCH-A and SCH-G have better filtering effects with the same variance. Meanwhile, the larger the template size is, the better filtering effect SCH-A has. This conclusion is also applicable to SCH-G under the same variance.

B-Type Fumonisins in Post-Fermented Tea: Occurrence and Consumer Dietary Exposure in Guangxi, China.

Post-fermented tea (PFT), a commonly consumed beverage worldwide, is characterized by the rapid growth of its microbial groups and the substantial changes they undergo. Consequently, PFT may contain mycotoxins such as B-type fumonisins (FBs). This study aimed to assess the intake of FBs through the consumption of PFT among consumers in Guangxi, China. A novel quantitative method using high-performance liquid chromatography-mass spectrometry was used to determine the FB concentration in PFT products. Additionally, a PFT consumption survey was conducted using a face-to-face questionnaire, recording their body weight and PFT consumption patterns based on a three-day dietary recall method. Finally, hazard index was calculated to estimate the health risk of FBs from the consumption of PFT products in Guangxi. The results revealed that the occurrence of FBs in PFT was 20% (24/120), with a concentration ranging from 2.14 to 18.28 µg/kg. The results of the survey showed that the average daily consumption of PFT by consumers was 9.19 ± 11.14 g. The deterministic risk assessment revealed that only 0.026% of the provisional maximum tolerable daily intake of FBs was consumed through PFT, indicating that FB contamination in PFT is not a public health risk.

Metatranscriptomic analysis revealed Prevotella as a potential biomarker of oropharyngeal microbiomes in SARS-CoV-2 infection.

Background and objectives: Disease severity and prognosis of coronavirus disease 2019 (COVID-19) disease with other viral infections can be affected by the oropharyngeal microbiome. However, limited research had been carried out to uncover how these diseases are differentially affected by the oropharyngeal microbiome of the patient. Here, we aimed to explore the characteristics of the oropharyngeal microbiota of COVID-19 patients and compare them with those of patients with similar symptoms. Methods: COVID-19 was diagnosed in patients through the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by quantitative reverse transcription polymerase chain reaction (RT-qPCR). Characterization of the oropharyngeal microbiome was performed by metatranscriptomic sequencing analyses of oropharyngeal swab specimens from 144 COVID-19 patients, 100 patients infected with other viruses, and 40 healthy volunteers. Results: The oropharyngeal microbiome diversity in patients with SARS-CoV-2 infection was different from that of patients with other infections. Prevotella and Aspergillus could play a role in the differentiation between patients with SARS-CoV-2 infection and patients with other infections. Prevotella could also influence the prognosis of COVID-19 through a mechanism that potentially involved the sphingolipid metabolism regulation pathway. Conclusion: The oropharyngeal microbiome characterization was different between SARS-CoV-2 infection and infections caused by other viruses. Prevotella could act as a biomarker for COVID-19 diagnosis and of host immune response evaluation in SARS-CoV-2 infection. In addition, the cross-talk among Prevotella, SARS-CoV-2, and sphingolipid metabolism pathways could provide a basis for the precise diagnosis, prevention, control, and treatment of COVID-19.

Encrypting orbital angular momentum holography with ghost imaging.

In this paper, we propose a multiple images simultaneous encryption scheme by encrypting the orbital angular momentum (OAM) holography with ghost imaging. By controlling the topological charge of the incident OAM light beam on the OAM-multiplexing hologram, different images can be selectively obtained for ghost imaging (GI). Followed by the random speckles illumination, the bucket detector values in GI are obtained and then considered as the ciphertext transmitted to the receiver. The authorized user can distill the correct relationship between the bucket detections and the illuminating speckle patterns with the key and the additional topological charges, so that each holographic image can be successfully recovered, while the eavesdropper can not obtain any information about the holographic image without the key. The eavesdropper even can not get clear holographic image when all the key is eavesdropped but without topological charges. The experimental results show that the proposed encryption scheme has a higher capacity for multiple images because there is no theoretical topological charge limit for the selectivity of OAM holography, and the results also show that the proposed encryption scheme is more secure and has a stronger robustness. Our method may provide a promising avenue for multi-image encryption and has the potential for more applications.

Secret sharing scheme based on spread spectrum ghost imaging.

(n,n) secret sharing is a procedure for splitting the key into several pieces so that no subset is sufficient to read the encrypted message except the entire one. In this paper, we propose a novel, to the best of our knowledge, secret sharing scheme based on spread spectrum ghost imaging (SSGI). In the scheme, a dealer divides a secret key, which is obtained by a modulo 2 addition over n sequences from a Hadamard matrix, into n pieces to n participants, and then the dealer uses the secret key as a direct sequence code to encrypt an image using the SSGI method. The resultant bucket signal, as the ciphertext, is then shared with n participants, and the modulated speckle patterns in SSGI are also transmitted to nparticipants by private channels for preventing eavesdropping. An independent signal is used as a protective signal to prevent the information leakage in SSGI. In the decryption process, only if all participants are honest and cooperative, the secret key can be obtained; thus, the ciphertext can be decrypted to the correct image using the second-order correlation algorithm. Otherwise, the image information cannot be extracted. The theoretical analysis shows that the probability of finding out others' pieces for successfully reconstructing the image for one dishonest participant is (1/2N)n-1, where N is the length of the secret key, and n is the number of participants. The simulation and experimental results demonstrate that the proposed scheme has a stronger data security capacity in optical information encryption.

Diffractive deep neural network based adaptive optics scheme for vortex beam in oceanic turbulence.

Vortex beam carrying orbital angular momentum (OAM) is disturbed by oceanic turbulence (OT) when propagating in underwater wireless optical communication (UWOC) system. Adaptive optics (AO) is a powerful technique used to compensate for distortion and improve the performance of the UWOC system. In this work, we propose a diffractive deep neural network (DDNN) based AO scheme to compensate for the distortion caused by OT, where the DDNN is trained to obtain the mapping between the distortion intensity distribution of the vortex beam and its corresponding phase screen representing OT. In the experiment, the distorted vortex beam is input into the DDNN model where the diffractive layers are solidified and fabricated, and the intensity distribution of the modulated light field of the vortex beam can be recorded. The experiment results show that the proposed scheme can extract quickly the characteristics of the intensity pattern of the distorted vortex beam, and the predicted compensation phase screen can correct the distortion caused by OT in time. The mode purity of the compensated vortex beam is significantly improved, even with a strong OT. Our scheme may provide a new avenue for AO techniques, and is expected to promote the communication quality of UWOC system immediately.

Sending-or-Not-Sending Twin-Field Quantum Key Distribution with a Passive Decoy-State Method.

Twin-field quantum key distribution (TF-QKD) has attracted considerable attention because it can exceed the basic rate-distance limit without quantum repeaters. Its variant protocol, sending or not-sending quantum key distribution (SNS-QKD), not only fixes the security vulnerability of TF-QKD, but also can tolerate large misalignment errors. However, the current SNS-QKD protocol is based on the active decoy-state method, which may lead to side channel information leakage when multiple light intensities are modulated in practice. In this work, we propose a passive decoy-state SNS-QKD protocol to further enhance the security of SNS-QKD. Numerical simulation results show that the protocol not only improves the security in source, but also retains the advantages of tolerating large misalignment errors. Therefore, it may provide further guidance for the practical application of SNS-QKD.

Prefixed-Threshold Real-Time Selection for Free-Space Sending-or-Not Twin-Field Quantum Key Distribution.

As a variant of the twin-field quantum key distribution (TF-QKD), the sending-or-not twin-field quantum key distribution (SNS TF-QKD) is famous for its higher tolerance of misalignment error, in addition to the capacity of surpassing the rate-distance limit. Importantly, the free-space SNS TF-QKD will guarantee the security of the communications between mobile parties. In the paper, we first discuss the influence of atmospheric turbulence (AT) on the channel transmittance characterized by the probability distribution of the transmission coefficient (PDTC). Then, we present a method called prefixed-threshold real-time selection (P-RTS) to mitigate the interference of AT on the free-space SNS TF-QKD. The simulations of the free-space SNS TF-QKD with and without P-RTS are both given for comparison. The results showed that it is possible to share the secure key by using the free-space SNS TF-QKD. Simultaneously, the P-RTS method can make the free-space SNS TF-QKD achieve better and more stable performance at a short distance.

Ghost edge detection based on HED network.

In this paper, we present an edge detection scheme based on ghost imaging (GI) with a holistically-nested neural network. The so-called holistically-nested edge detection (HED) network is adopted to combine the fully convolutional neural network (CNN) with deep supervision to learn image edges effectively. Simulated data are used to train the HED network, and the unknown object's edge information is reconstructed from the experimental data. The experiment results show that, when the compression ratio (CR) is 12.5%, this scheme can obtain a high-quality edge information with a sub-Nyquist sampling ratio and has a better performance than those using speckle-shifting GI (SSGI), compressed ghost edge imaging (CGEI) and subpixel-shifted GI (SPSGI). Indeed, the proposed scheme can have a good signal-to-noise ratio performance even if the sub-Nyquist sampling ratio is greater than 5.45%. Since the HED network is trained by numerical simulations before the experiment, this proposed method provides a promising way for achieving edge detection with small measurement times and low time cost.

Multi-Gaussian correlated Hankel-Bessel beam properties in anisotropic oceanic turbulence.

We introduce the model of a multi-Gaussian correlated Hankel-Bessel (MGCHB) beam generated by a multi-Gaussian Shell-model source and investigate the properties of the beam in anisotropic oceanic turbulence. Under Rytov approximation, the detection probability of the MGCHB beam and the channel capacity with MGCHB beams are derived; both the influence of oceanic turbulence and initial beam parameters on them are discussed by numerical simulations. The results show that the increase of the dissipation rate of kinetic energy per unit mass of fluid, the anisotropic coefficient, and the inner scale factor, as well as the decrease of the dissipation rate of mean-squared temperature and the temperature-salinity contribution ratio, can significantly improve the detection probability and the channel capacity. The results also indicate that the MGCHB beam is a better candidate than an Airy vortex beam for mitigating the influence of oceanic turbulence. Furthermore, smaller topological charge and larger orbital angular momentum modes number are beneficial to improve the detection probability and channel capacity, respectively. Moreover, the performance of the MGCHB beam with longer wavelength, smaller beam index, and larger transverse coherence width is conducive to enhancing the transmission quality through oceanic turbulence.

Full color single pixel imaging by using multiple input single output technology.

In this paper, we propose a novel full color single pixel imaging by using multiple input single output (MISO) technology. In the scheme, the MISO technology, which is widely used in the wireless communications, is used to simultaneously produce three (red, green and blue) detection signal components corresponding to the red, green and blue components of the object with only one single pixel bucket detector respectively. Then, a full color image of object can be produced by synthesizing the reconstructed red, green and blue component images of object, where the red (green or blue) component image can be recovered by utilizing the speckle patterns and corresponding detection signal components. The experimental results demonstrate that our scheme can be robust against the interference of the intensity fluctuations of ambient light and improve the imaging quality. Moreover, our scheme requires only one single pixel bucket detector, which reduces the numbers of bucket detectors that need to be used. Our scheme provides a promising avenue to realize the full color single pixel imaging with MISO technology and has the potential to be extended to high quality multispectral single pixel imaging by using only one single pixel detector.

Isotropic and anisotropic edge enhancement with a superposed-spiral phase filter.

In this paper, we present edge detection schemes with specially designed superposed spiral phase plate (SSPP) filters in the Fourier domain both for intensity or phase objects. A special SSPP whose function is equivalent to Sobel operator in space domain is firstly designed by weighting different topological charge spiral phase plate (SPP) filters. Later, a SSPP with controllable direction parameters is then discussed to enhance the anisotropic edges by controlling the direction parameter. Numerical simulation and experimental results show that either isotropic or anisotropic edge information can be enhanced by using our proposed schemes. The signal-to-noise ratio and the root-mean-square-error performance are improved in comparison with those using traditional SPP filter. Importantly, it is the first time to present the special ways of superposing and the SSPP can be designed before the experiment so that a clear edge can be achieved at real time without the convolutional operation.

Decoy-state phase-matching quantum key distribution with source errors.

The phase-matching quantum key distribution (PM-QKD), one of the variants of Twin-Field (TF) QKD protocol, was recently proposed to overcome the rate-distance limits of point to point protocol without quantum repeaters. In this paper, we propose a more practical PM-QKD protocol version with four-intensity decoy states and source errors, since neither the infinite decoy states nor the precise control of the light source is available in practice. We present the formulation of the secure key rate of the proposed protocol and analyze the performances of the protocol with and without source errors by numerical simulations.

Role of platelet infiltration as independent prognostic marker for gastric adenocarcinomas.

BACKGROUND: In recent years, the relationship between malignant tumors and platelets has been paid more attention. The increase of platelets is an independent risk factor for the poor prognosis of some malignant tumors. METHODS: This study retrospectively analyzed the clinical and pathological data of 114 patients with initial gastric cancer from August 2005 to August 2018 in Shandong Provincial Hospital. Single-factor and multifactor survival analysis were used to evaluate the effect of platelet elevation on postoperative survival. The gastric cancer tissues of the Jinan Central Hospital and its matched paracancerous tissues were collected. The expression of platelets in tissues was detected by immunofluorescence technique. Different numbers of platelets were co-cultured with MKN-45 cells, CCK-8 assay and transwell assay were performed, and the expression of epithelial-mesenchymal transition-related proteins was detected. RESULTS: Platelet count was independent factors affecting prognosis. The stratified analysis showed that there was a statistically significant difference in the 5-year survival rate between the platelet-increase group and the normal platelet group in the TNM stages I-II. The expression of platelets in gastric cancer tissues was higher than that in adjacent tissues. The results of CCK-8 and transwell showed that platelets significantly enhanced the proliferation and metastasis capability of MKN-45 cells in a concentration-dependent manner. After co-culture, the expression level of E-cadherin protein in MKN-45 cells decreased, and the protein expression levels of N-cadherin, vimentin, and VEGFA increased. CONCLUSION: Platelet elevation is closely related to the occurrence, development, and metastasis of gastric cancer, and platelet count can be used as a prognostic indicator for malignant tumors.

Author Correction: An Effective Way for Simulating Oceanic Turbulence Channel on the Beam Carrying Orbital Angular Momentum.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

An Effective Way for Simulating Oceanic Turbulence Channel on the Beam Carrying Orbital Angular Momentum.

In this paper, we present an effective way for simulating oceanic turbulence channel on the beam carrying orbital angular momentum (OAM). The influence caused by oceanic turbulence channel on the phase and intensity of the propagation beam is equivalent to that the beam passing through several individual phase screens generated by power spectrum inversion method at regular intervals. A modified subharmonic compensation method is then further balance the phase screen for the losses of lower frequency components in the power spectrum inversion method. The feasibility is verified by the theoretical phase structure function and the propagation characteristics of an OAM beam in underwater environment. The results show that the phase structure function and the propagation characteristics of the OAM beam evaluated by the phase screen model all coincide with those theoretical results at high spatial frequency. Simultaneously, the low frequency components could be effectively compensated by the modified subharmonic method. With the increase of the subharmonic order and sample level, the performance evaluated by the phase screen model are closer to the theoretical ones. It has provided an effective way for simulating oceanic turbulence channel for the underwater optical communications.

Phase Matching Quantum Key Distribution based on Single-Photon Entanglement.

Two time-reversal quantum key distribution (QKD) schemes are the quantum entanglement based device-independent (DI)-QKD and measurement-device-independent (MDI)-QKD. The recently proposed twin field (TF)-QKD, also known as phase-matching (PM)-QKD, has improved the key rate bound from O(η) to O[Formula: see text] with η the channel transmittance. In fact, TF-QKD is a kind of MDI-QKD but based on single-photon detection. In this paper, we propose a different PM-QKD based on single-photon entanglement, referred to as single-photon entanglement-based phase-matching (SEPM)-QKD, which can be viewed as a time-reversed version of the TF-QKD. Detection loopholes of the standard Bell test, which often occur in DI-QKD over long transmission distances, are not present in this protocol because the measurement settings and key information are the same quantity which is encoded in the local weak coherent state. We give a security proof of SEPM-QKD and demonstrate in theory that it is secure against all collective attacks and beam-splitting attacks. The simulation results show that the key rate enjoys a bound of O[Formula: see text] with respect to the transmittance. SEPM-QKD not only helps us understand TF-QKD more deeply, but also hints at a feasible approach to eliminate detection loopholes in DI-QKD for long-distance communications.

Analytical comparison between two hematological analyzer systems: Mindray BC-5180 vs Sysmex XN-1000.

BACKGROUND: To compare the Mindray BC-5180 and Sysmex XN-1000 instruments by analyzing the results of complete blood count in the external quality assessment in Shandong Province in 2018. METHODS: In the external quality assessment, 10 batches of quality control materials were issued throughout the year. The test items were WBC, RBC, Hb, PLT, and HCT. The laboratories using Mindray BC-5180 and Sysmex XN-1000 were screened, and the results were analyzed by t test, Passing-Bablok regression analysis, and Bland-Altman analysis. RESULTS: Thirty-six laboratories using Mindray BC-5180 instruments and thirty-six laboratories using Sysmex XN-1000 instruments were screened, and the average difference between the two instruments results is not significant (P > 0.05, t test). Passing-Bablok regression analysis showed that the 95% confidence interval of the regression equation interception of each test item included 0, and the 95% confidence interval of the slope contained 1, r > 0.98, which showed that the correlation is good. The Bland-Altman analysis showed that both instruments had more than 95% of the points within the 95% consistency limit (WBC97.2%, RBC95.6%, PLT97.2%, Hb96.7%, HCT97.5%). Within the consistency limit, the absolute value of the difference between the Mindray BC-5180 instrument and the Sysmex XN-1000 instrument is WBC 0.14%, RBC 0.26%, PLT 2.7%, and Hb 1.9%. HCT is 0.69%, and the difference is clinically acceptable. CONCLUSION: It can be considered that the two instruments have good correlation and consistency, and the two instruments can replace each other.

Propagation and self-healing properties of Bessel-Gaussian beam carrying orbital angular momentum in an underwater environment.

In this paper, we report on experimental demonstration of the propagation and self-healing property of Bessel-Gaussian (BG) beam carrying orbital angular momentum (OAM) in an underwater environment. Especially, the effects of topological charge, temperature gradient, and salinity on the transmission and self-reconstruction of BG beam in underwater turbulence are analyzed. The results show that the detection probabilities both for propagation and self-healing greatly decrease with temperature gradient, and gradually decrease with salinity. BG beam has a self-healing property in the underwater environment when the obstruction is quite small. The detection probability greatly decreases with obstruction size, while it gradually decreases with salinity fluctuations for different obstruction sizes. For the same blockage ratio, the smaller topological charge of BG beam is, the better self-healing characteristics the BG beam has.

Manipulating orbital angular momentum entanglement by using the Heisenberg uncertainty principle.

Orbital angular momentum entanglement (OAM) is one of the very intriguing topics in quantum physics. In addition to discovering and exploring its underlying mechanics, recent studies have also demonstrated a progress towards expanding degree of its entanglement. In this paper, we explore OAM entanglement by applying the Heisenberg uncertainty principle to the quantum position correlation within the azimuthal region. In particular, we decompose the pump light into a set of pump cone states characterized by their radii. The OAM entanglement can then be manipulated by controlling the radius of the pump cone state, the length of the nonlinear crystal and also the OAM carried by the pump field. That is followed by a detailed discussion and analysis. Such an exploration not only bring us a deeper understanding of OAM entanglement, but also help us to implement the high-dimensional quantum information tasks based on OAM entanglement.