Real-time stealth optical transmission via dither-remodulation in a bias controller of a Mach-Zehnder modulator.

The physical layer transmission security is a promising technology against security threats. As an effective supplement to the encryption strategy, steganography has received widespread attention. We report a real-time 2 kbps stealth transmission in the 10 Gbps dual polarization QPSK public optical communication. The stealth data is embedded in dither signals via precise and stable bias control technique for a Mach-Zehnder modulator. In the receiver, the stealth data can be recovered from the normal transmission signals by low SNR signal processing and digital down conversion. The stealth transmission has been verified to pose almost no impact on the public channel over a 117 km distance. The proposed scheme is compatible with existing optical transmission systems, so that no new hardware needs to be employed. It can be accomplished and is exceeded economically by adding simple algorithms, which utilizes only a small amount of FPGA resources. The proposed method can cooperate with encryption strategies or cryptographic protocols at different network layers to reduce the communication overhead and improve the overall security of the system.

Secure key distribution based on the polarization reciprocity of fiber and a coherent reception architecture.

Secure key distribution (SKD) schemes based on the interaction between a broadband chaotic source and the reciprocity of a fiber channel exhibit reliable security and a high key generation rate (KGR). However, under the intensity modulation and direct detection (IM/DD) architecture, these SKD schemes cannot achieve a long distribution distance due to the limitations on the signal-to-noise ratio (SNR) and the receiver's sensitivity. Here, based on the advantage of the high sensitivity of coherent reception, we design a coherent-SKD structure where orthogonal polarization states are locally modulated by a broadband chaotic signal and the single-frequency local oscillator (LO) light is transmitted bidirectionally in the optical fiber. The proposed structure not only utilizes the polarization reciprocity of optical fiber but also largely eliminates the non-reciprocity factor, which can effectively extend the distribution distance. The experiment realized an error-free SKD with a transmission distance of 50 km and a KGR of 1.85 Gbit/s.

Stable secure key distribution scheme via orthogonal polarizations and a joint source-channel model.

Optical secure key distribution (SKD) based on reciprocity has been the subject of increasing discussion, for its inherent information-theoretic safety and because there is less occupation of fiber channels. The combination of reciprocal polarization and broadband entropy sources has proven effective in increasing the rate of SKD. However, the stabilization of such systems suffers from the limited span of polarization states and inconsistent polarization detection. The specific causes are analyzed in principle. To solve this issue, we propose a strategy for extracting secure keys from orthogonal polarizations. Optical carriers with orthogonal polarizations at interactive parties are modulated by external random signals using polarization division multiplexing dual-parallel Mach-Zehnder modulators. After bidirectional transmission through a 10-km fiber channel, error-free SKD with a rate of 2.07 Gbit/s is experimentally realized. The high correlation coefficient of the extracted analog vectors can be maintained for over 30 min. The proposed method is a step toward the development of secure communication with high speed and feasibility.

High-speed secure key distribution using local polarization modulation driven by optical chaos in reciprocal fiber channel.

We propose a secure key distribution (SKD) based on local polarization modulation driven by optical chaos in a reciprocal fiber link. A robust error-free SKD with a key generation rate of 4.3 Gbit/s over transmission of 10-km standard single-mode fiber is experimentally demonstrated. A chaotic laser system shared by legitimate users serves as an external wideband entropy source. The polarization reciprocity of the fiber channel provides fundamental safety against eavesdropping. The robustness of SKD resulted from local chaotic polarization modulation is also theoretically analyzed and then verified by practical performance. The proposed scheme is an alternative SKD strategy with high speed and strong security.

Analog-digital hybrid chaos-based long-haul coherent optical secure communication.

We propose and numerically investigate a chaotic optical coherent secure communication scheme, which supports long-haul secure transmission for signals in advanced modulation formats. A hybrid optical chaos system is designed with coordination of digital and analog signals. The hybrid entropy source provides a broadband analog optical chaos signal, which could serve as the carrier to load quadrature amplitude modulation (QAM) data. Simultaneously, a digital binary signal generated from the entropy source is transmitted to establish long-haul chaotic synchronization. Coherent detection is utilized at the receiver, and a digital signal processing (DSP) algorithm is adopted to reduce transmission distortion. A 5 Gbaud 16QAM signal is encrypted by a phase chaos carrier with the effective bandwidth of 5.8 GHz. A bit error rate (BER) below forward error correction (FEC) can be achieved after transmitting over 1600 km based on digital-signal-induced chaos synchronization technology. Optimal launch power is investigated to minimize nonlinear effects of transmission links. System security is guaranteed by the high dynamical complexity of the chaotic source and the sensitive time delay as the secret key.

Experimental demonstration of a broadband optoelectronic chaos system based on highly nonlinear configuration of IQ modulator.

We experimentally investigated a novel broadband optoelectronic chaos generation scheme. The proposed system is achieved by adopting the highly nonlinear operation of an electro-optical exclusive-NOR (XNOR) logic gate and two delayed feedback loops that refer to the Boolean chaos model. The XNOR gate is established by a commercial use inphase and quadrature-phase (IQ) modulator that works at a specific bias point. The resulting power spectrum of the broadband chaos signal extends from DC to 29.1 GHz (10 dB bandwidth), and the probability density distribution is Gaussian distribution like. Owing to the strong nonlinearity of XNOR operation, the conditions to enter the chaos region are more relaxed compared to traditional optoelectronic oscillator (OEO) chaos systems, and the time delay signature (TDS) of the feedback loop is also suppressed. Moreover, to further enhance the performance of the generated chaos signal, we injected the optoelectronic chaotic signal into a semiconductor laser. Experimental results indicate that after the cascade optical injection, the bandwidth of the output chaos signal is extended to 38.4 GHz and the TDS is completely concealed; meanwhile, a perfect Gaussian distribution can be obtained.

Modulation format-independent optical performance monitoring technique insensitive to chromatic dispersion and polarization mode dispersion using a multi-task artificial neural network.

We propose and experimentally demonstrate modulation format-independent optical performance monitoring (OPM) based on a multi-task artificial neural network (MT-ANN). Optical power measurements at a series of center wavelengths adjusted using a widely tunable optical bandpass filter (OBPF) are used as the input features for a MT-ANN to simultaneously realize high-precision optical signal-to-noise ratio (OSNR) and launch power monitoring and baud rate identification (BRI). This technique is insensitive to chromatic dispersion (CD) and polarization mode dispersion (PMD). The experimental verification in a 9-channel WDM system shows that for 10 Gbaud QPSK and 32 Gbaud PDM-16QAM signals with OSNR in the range of 1-30 dB, the OSNR mean absolute error (MAE) and root mean square error (RMSE) are 0.28 dB and 0.48 dB, respectively. For launch power in the range of 0-8 dBm, the MAE and RMSE of the launch power monitoring are 0.034 dB and 0.066 dB, respectively, and the identification accuracy for both baud rates is 100%. Furthermore, this technique utilizes a single MT-ANN instead of three ANNs to realize the simultaneous monitoring of three OPM parameters, which greatly reduces the cost and complexity.

Unveil the time delay signature of optical chaos systems with a convolutional neural network.

We propose a time delay signature extraction method for optical chaos systems based on a convolutional neural network. Through transforming the time delay signature of a one-dimensional time series into two-dimensional image features, the excellent ability of convolutional neural networks for image feature recognition is fully utilized. The effectiveness of the method is verified on chaos systems with opto-electronic feedback and all optical feedback. The recognition accuracy of the method is 100% under normal conditions. For the system with extremely strong nonlinearity, the accuracy can be 93.25%, and the amount of data required is less than traditional methods. Moreover, it is verified that the proposed method possesses a strong ability to withstand the effects of noise.

Multi-population genetic algorithm for peak-to-average power ratio suppression in an optical OFDM transmission system.

We proposed and experimentally demonstrated the parallel multi-population genetic algorithm (MPGA)-based selected mapping (SLM) technique to reduce the peak-to-average power ratio of the optical orthogonal frequency-division multiplexing system. By introducing the parallel genetic algorithm (GA), the MPGA-SLM can effectively escape the local optimization of the conventional GA and attains fast convergence on the global optimization. Compared with the conventional SLM method, we experimentally achieved 1-dB performance improvement at a 3.8×10-3 bit error ratio by utilizing the MPGA-SLM in the back-to-back case and that of 0.7 dB in the 30-km single-mode fiber transmission case.

Deep neuromuscular block attenuates intra-abdominal pressure and inflammation and improves post-operative cognition in prostate cancer patients following robotic-assisted radical prostatectomy.

BACKGROUND: Whether neuromuscular block (NMB) affects Intra-abdominal pressure (IAP) and cognition in Prostate cancer (PC) patients with Robotic-assisted laparoscopic radical prostatectomy (RALRP) remains unclear. Here we aimed to compare the effects of deep and moderate NMB on the IAP, inflammation, and cognition. METHODS: The Moderate neuromuscular block (MNMB) group (N = 44) and Deep neuromuscular block (DNMB) group (N = 47) were recruited. Intra-abdominal pressure was adjusted to meet RALRP requirements. The expression of pro-inflammatory factors was measured by ELISA. MMSE scores were recorded before the operation, 1 day and 1 week after the operation. RESULTS: Significant decreases in IAP (p < 0.001) and IL-1ß, IL-6, TNF-a, and S-100ß (p ≤ 0.01) expressions were found in the DNMB group. The MMSE score in the DNMB group was higher than that in the MNMB group on day one (p = 0.046). The incidence of nausea and vomiting was lower in the DNMB group than that in the MNMB group (p = 0.013). CONCLUSIONS: DNMB reduces IAP and inflammation and improves post-operative cognitive functions in PC patients with RALRP.

MicroRNA-214-5p involves in the protection effect of Dexmedetomidine against neurological injury in Alzheimer's disease via targeting the suppressor of zest 12.

OBJECTIVE: Alzheimer's disease (AD) is a neurological disease. Dexmedetomidine (Dex) has been evidenced to exert neuroprotective effects on multiple neurological diseases, while the function of microRNA(miR)- 214-5p on Dex-mediated AD progression via targeting the suppressor of zest 12 (SUZ12) remains unclear. This study obligates to investigate the regulatory functions of Dex, miR-214-5p and SUZ12 on AD. METHODS: The expression of miR-214-5p and SUZ12 in APPswe/PS1dE9 mice (hereinafter referred to as AD mice) was examined. Thereafter, the AD mice were treated with Dex or increased miR-214-5p or reduced SUZ12 to determine the spatial memory ability, apoptosis of hippocampal neurons and the contents of serum inflammatory and oxidative stress factors of AD mice. Finally, the target relationship between miR-214-5p and SUZ12 was detected. RESULTS: MiR-214-5p was reduced and SUZ12 was elevated in AD mice. Dex administration reduced the apoptosis of hippocampal neurons, the contents of serum inflammatory factor and oxidative stress, and attenuated the cognitive impairment of AD mice accompanied by up-regulated miR-214-5p and down-regulated SUZ12, and the overexpression of miR-214-5p or reduction of SUZ12 could effectively enhance the Dex-treated effects on AD mice. MiR-214-5p targeted SUZ12. CONCLUSION: Dex may have a potential neuroprotective effect on AD via the miR-214-5p/SUZ12 axis. This study provides novel therapeutic targets for AD treatment.

Detection of physical descaling damage in carp based on hyperspectral images and dimension reduction of principal component analysis combined with pixel values.

The surface of carp is easily damaged during the descaling process, which jeopardizes the quality and safety of carp products. Damage recognition realized by manual detection is an important factor restricting the automation in the pretreatment. For the commonly used methods of mechanical and water-jet descaling, damage area recognition according to the hyperspectral data was proposed. Two discrimination models, including decision tree (DT) and self-organizing feature mapping (SOM), were established to recognize the damaged and normal descaling area with the average spectral value. The damage-discrimination model based on DT was determined to be the optimal one, which possessed the best model performance (accuracy = 96.7%, sensitivity = 96.7%, specificity = 96.7%, F1-score = 96.7%). Considering the efficiency and precision of damage-area recognition and visualization, the principal component analysis (PCA) combined with pixel values statistical analysis was used to reduce the dimension of hyperspectral images at the image level. Through statistical analysis, the value 0 was used as the threshold to distinguish the normal area and the damaged area in the PC image to achieve preliminary segmentation. Then, the spectral values of the initially discriminated damage area were input into the DT discrimination model to realize the final discriminant of damaged area. On this basis, the position information of the damaged area could be used to realize the visualization. The final visualization maps for mechanical and water-jet descaling damage were obtained by image morphology processing. The average recognition accuracy can reach 94.9% and 90.3%, respectively. The results revealed that the hyperspectral imaging technique has great potential to recognize the carp damage area nondestructively and accurately under descaling processing. PRACTICAL APPLICATION: This study demonstrated that hyperspectral imaging technique can realize the carp damage area detection nondestructively and accurately under descaling processing. With the advantages of nondestructive and rapid, hyperspectral imaging system and the method can be widely expanded and applied to the quality detection of other freshwater fish pretreatment.

Detection of moisture content in salted sea cucumbers by hyperspectral and low field nuclear magnetic resonance based on deep learning network framework.

The accurate control of moisture content (MC) during the processing of sea cucumber is beneficial to improve the taste of sea cucumber and maintain its nutritional value, which is directly related to the quality and shelf life of sea cucumber. The purpose of this study is to explore the feasibility using deep learning (DL) to realize rapid nondestructive detection of MC in salted sea cucumbers based on hyperspectral imaging (HSI) and low field nuclear magnetic resonance (LF-NMR) data. Firstly, three Cuckoo Search (CS) dimensionality reduction algorithms (Traditional-CS, Binary-CS and Chaotic-CS) were combined with DL framework respectively using HSI and LF-NMR data to establish prediction models, which proved the feasibility of DL framework in predicting the MC of sea cucumbers, and Chaotic-CS algorithm was selected as the optimal dimensionality reduction algorithm. Then, the MC visualization based on HSI and LF-NMR data was realized respectively to detect the migration and decrease of MC. Finally, using both HSI and LF-NMR data, the advantages of the models based on Fusion-net DL (FDL) framework were discussed, which showed better performance than the single-data models, with RC2 of 0.9929, RMSEC of 0.0016, RP2 of 0.9936 and RPD of 12.5041. In summary, the rapid nondestructive detection of MC in salted sea cucumbers could be realized by HSI and LF-NMR data based on DL framework, and the advantage of data fusion detection based on FDL framework was verified.

Perioperative stress prolong post-surgical pain via miR-339-5p targeting oprm1 in the amygdala.

Background: The decreased expression of mu-opioid receptors (MOR) in the amygdala may be a key molecular in chronic post-surgical pain (CPSP). It is known that miR-339-5p expression in the amygdala of a stressed rat model was increased. Analyzed by RNAhybrid, miR-339-5p could target opioid receptor mu 1 (oprm1) which codes MOR directly. So, the authors hypothesized that miR-339-5p could regulate the expression of MOR via targeting oprm1 and cause the effects to CPSP. Methods: To simulate perioperative short-term stress, a perioperative stress prolongs incision-induced pain hypersensitivity without changing basal pain perception rat model was built. A pmiR-RB-REPORT™ dual luciferase assay was taken to verify whether miR-339-5p could act on oprm1 as a target. The serum glucocorticoid level of rats was test. Differential expressions of MOR, GFAP, and pERK1/2 in each group of the rats' amygdala were tested, and the expressions of miR-339-5p in each group of rats' amygdalas were also measured. Results: Perioperative stress prolonged the recovery time of incision pain. The expression of MOR was down-regulated in the amygdala of rats in stress + incision (S + IN) group significantly compared with other groups (P < 0.050). miR-339-5p was up-regulated in the amygdala of rats in group S + IN significantly compared with other groups (P < 0.050). miR-339-5p acts on oprm1 3'UTR and take MOR mRNA as a target. Conclusions: Perioperative stress could increase the expression of miR-339-5p, and miR-339-5p could cause the expression of MOR to decrease via targeting oprm1. This regulatory pathway maybe an important molecular mechanism of CPSP.

General anesthesia versus monitored anesthesia care during endovascular therapy for vertebrobasilar stroke.

OBJECTIVE: The objective is to compare the effect of general anesthesia (GA) and monitored anesthesia care (MAC) on clinical outcomes in patients with endovascular therapy for vertebrobasilar occlusion stroke. METHODS: 139 patients undergoing endovascular therapy for vertebrobasilar stroke, were recruited. The patients were randomized into GA group and MAC group (about 1:1 ratio). GA group received general anesthesia and MAC group received monitored anesthesia care during endovascular therapy. The primary outcome measure was the shift in the degree of disability among the 2 groups as measured by the modified Rankin scale score (mRS) at 90 days (80-100 days). Secondary end points included infarct volume and related complications. RESULTS: The patients were assigned randomly (about 1:1 allocation) to GA group (n=72) and MAC group (n=67). The primary outcome of functional independence measured by 90-day mRS score was not significantly different between the 2 groups (median (IQR), 2 (1-3) vs. 3 (1-4); P=0.316). Final infarct volume was smaller in the GA group than in the MAC group (median (IQR), 27.60 (13.75-83.52) vs. 33.60 (26.85-92.95); P=0.045). There were no differences with statistical significance in rates of successful reperfusion (modified Thrombolysis in Cerebral Ischemia (mTICI) 2b-3) between 2 groups (73.61% vs. 76.12%; P=0.734). Early neurological outcomes measured by the 24-hour National Institutes of Health Stroke Scale scores (NIHSS) showed that 11 (interquartile range (IQR), 3-22) in GA group and 11 (interquartile range (IQR), 7-25) in MAC group, but were not statistically significant. There was no statistical difference in postoperative complications between the two groups. CONCLUSION: For patients who underwent endovascular therapy for vertebrobasilar occlusion strok caused by occlusions in the posterior circulation, MAC appears to be as effective as GA. However, MAC is associated with bigger final infarct volume. Future studies are warranted to confirm our findings.

Phylogenetic analyses and characteristics of the microbiomes from five mealybugs (Hemiptera: Pseudococcidae).

Associations between Sternorrhyncha insects and intracellular bacteria are common in nature. Mealybugs are destructive pests that seriously threaten the production of agriculture and forestry. Mealybugs have evolved intimate endosymbiotic relationships with bacteria, which provide them with essential amino acids, vitamins, and other nutrients. In this study, the divergence of five mealybugs was analyzed based up the sequences of the mitochondrial cytochrome oxidase I (mtCOI). Meanwhile, the distinct regions of the 16S rRNA gene of primary symbionts in the mealybugs were sequenced. Finally, high-throughput sequencing (HTS) techniques were used to study the microbial abundance and diversity in mealybugs. Molecular phylogenetic analyses revealed that these five mealybugs were subdivided into two different clusters. One cluster of mealybugs (Dysmicoccus neobrevipes, Pseudococcus comstocki, and Planococcus minor) harbored the primary endosymbiont "Candidatus Tremblaya princeps," and another cluster (Phenacoccus solenopsis and Phenacoccus solani) harbored "Ca. Tremblaya phenacola." The mtCOI sequence divergence between the two clusters was similar to the 16S rRNA sequence divergence between T. princeps and T. phenacola. Thus, we concluded that the symbiont phylogeny was largely concordant with the host phylogeny. The HTS showed that the microbial abundance and diversity within P. solani and P. solenopsis were highly similar, and there was lower overall species richness compared to the other mealybugs. Among the five mealybugs, we also found significant differences in Shannon diversity and observed species. These results provide a theoretical basis for further research on the coevolution of mealybugs and their symbiotic microorganisms. These findings are also useful for research on the effect of symbiont diversity on the pest status of mealybugs in agricultural systems.

Rapid identification of the Asian gypsy moth and its related species based on mitochondrial DNA.

The gypsy moth-Lymantria dispar (Linnaeus)-is a worldwide forest defoliator and is of two types: the European gypsy moth and the Asian gypsy moth. Because of multiple invasions of the Asian gypsy moth, the North American Plant Protection Organization officially approved Regional Standards for Phytosanitary Measures No. 33. Accordingly, special quarantine measures have been implemented for 30 special focused ports in the epidemic areas of the Asian gypsy moth, including China, which has imposed great inconvenience on export trade. The Asian gypsy moth and its related species (i.e., Lymantria monocha and Lymantria xylina) intercepted at ports are usually at different life stages, making their identification difficult. Furthermore, Port quarantine requires speedy clearance. As such, it is difficult to identify the Asian gypsy moth and its related species only by their morphological characteristics in a speedy measure. Therefore, this study aimed to use molecular biology technology to rapidly identify the Asian gypsy moth and its related species based on the consistency of mitochondrial DNA in different life stages. We designed 10 pairs of specific primers from different fragments of the Asian gypsy moth and its related species, and their detection sensitivity met the need for rapid identification. In addition, we determined the optimal polymerase chain reaction amplification temperature of the 10 pairs of specific primers, including three pairs of specific primers for the Asian gypsy moth (L. dispar asiatic), four pairs of specific primers for the nun moth (L. monocha), and three pairs of specific primers for the casuarina moth (L. xylina). In conclusion, using our designed primers, direct rapid identification of the Asian gypsy moth and its related species is possible, and this advancement can help improve export trade in China.