Learning Korobov Functions by Correntropy and Convolutional Neural Networks.

Combining information-theoretic learning with deep learning has gained significant attention in recent years, as it offers a promising approach to tackle the challenges posed by big data. However, the theoretical understanding of convolutional structures, which are vital to many structured deep learning models, remains incomplete. To partially bridge this gap, this letter aims to develop generalization analysis for deep convolutional neural network (CNN) algorithms using learning theory. Specifically, we focus on investigating robust regression using correntropy-induced loss functions derived from information-theoretic learning. Our analysis demonstrates an explicit convergence rate for deep CNN-based robust regression algorithms when the target function resides in the Korobov space. This study sheds light on the theoretical underpinnings of CNNs and provides a framework for understanding their performance and limitations.

A multivariate model based on gadoxetic acid-enhanced MRI using Li-RADS v2018 and other imaging features for preoperative prediction of dual­phenotype hepatocellular carcinoma.

OBJECTIVE: To investigate the diagnostic value of liver imaging reporting and data system (LI-RADS) v2018 and other imaging features in dual-phenotype hepatocellular carcinoma (DPHCC), establish a prediagnostic model based on gadoxetic acid-enhanced MRI, and explore the prognostic significance after surgery of the DPHCC. MATERIALS AND METHODS: Preoperative enhanced MRI findings and the clinical and pathological data of patients with surgically confirmed HCC were analysed retrospectively. Image analysis was based on LI-RADS v2018 and other image features. Univariate analysis was used to screen for predictive factors of DPHCC, and multivariate logistic regression analysis was used to determine the predictive factors. A regression diagnostic model was established. Receiver operating characteristic (ROC) curve analysis was used to determine the critical value, area under curve (AUC), and the corresponding 95% confidence interval (95% CI). The diagnostic performance was verified by fivefold cross-validation. Cox regression analysis was used to determine the prognostic factors associated with early recurrence after surgical resection. RESULTS: In total, 158 patients were included, of whom 79 had DPHCC and 79 had non-DPHCC. Multivariate analysis showed that rim arterial phase hyperenhancement (Rim APHE) and targetoid restriction were independent risk factors for DPHCC (P < 0.05). The AUC (95% CI) of the model was 0.862 (0.807-0.918), sensitivity was 81.01%, and specificity was 89.874%. Cox regression analysis showed that DPHCC, microvascular invasion, tumour diameter, and an increase of alpha-fetoprotein were independent factors for recurrence. CONCLUSION: Rim APHE and targetoid restriction were sensitive imaging features of DPHCC before surgery, and the identification of DPHCC has important prognostic significance for early recurrence.

Systemic evaluation of lymphocyte-bound C4d and immunoglobulins for diagnosis and activity monitoring of systemic lupus erythematosus.

OBJECTIVE: To investigate the role of lymphocyte-bound C4d (LB-C4d: T-C4d, B-C4d) and immunoglobulins (LB-Igs: T-IgG, T-IgM, B-κ and B-λ) in the diagnosis and monitoring of SLE. DESIGN & METHODS: The levels of C4d and Igs on peripheral lymphocytes were measured in 172 patients with SLE, 174 patients with other non-SLE inflammatory diseases and 100 healthy individuals. Immunobinding and blocking experiments were performed to characterize Igs from SLE patients to generate LB-C4d/Igs in vitro. Sixty-five patients with SLE were followed up longitudinally. Disease activity was assessed for each SLE patient. RESULTS: Patients with SLE had the highest median LB-C4d/Igs levels. LB-C4d had a significant but weak positive association with LB-Igs, with correlation coefficients ranging from 0.008 to 0.316. Anti-cardiolipin IgG and anti-ß2GP1 IgG, but not C3 and C4, were found to be closely associated with LB-C4d/Igs formation, with correlations as high as 0.337. Compared to anti-dsDNA, LB-C4d performed better in SLE diagnosis, while B-κ and B-λ performed better in disease activity monitoring. CONCLUSIONS: Both autoantibodies and receptors on lymphocytes contribute to LB-C4d/Igs formation. LB-C4d/Igs could be used as reliable indicators for SLE diagnosis and activity monitoring.

Micro-Motion Extraction for Marine Targets by Multi-Pulse Delay Conjugate Multiplication and Layered Tracking.

The detection and recognition of marine targets can be improved by utilizing the micro-motion induced by ocean waves. However, distinguishing and tracking overlapping targets is challenging when multiple extended targets overlap in the range dimension of the radar echo. In this paper, we propose a multi-pulse delay conjugate multiplication and layered tracking (MDCM-LT) algorithm for micro-motion trajectory tracking. The MDCM method is first applied to obtain the conjugate phase from the radar echo, which enables high-precision micro-motion extraction and overlapping state identification of extended targets. Then, the LT algorithm is proposed to track the sparse scattering points belonging to different extended targets. In our simulation, the root mean square errors of the distance and velocity trajectories were better than 0.277 m and 0.016 m/s, respectively. Our results demonstrate that the proposed method has the potential to improve the precision and reliability of marine target detection through radar.

Robust ring-opening reaction via asymmetrically coordinated Fe single atoms scaffolded by spoke-like mesoporous carbon nanospheres.

The ability to construct metal single-atom catalysts (SACs) asymmetrically coordinated with organic heteroatoms represents an important endeavor toward developing high-performance catalysts over symmetrically coordinated counterparts. Moreover, it is of key importance in creating supporting matrix with porous architecture for situating SACs as it greatly impacts the mass diffusion and transport of electrolyte. Herein, we report the crafting of Fe single atoms with asymmetrically coordinated nitrogen (N) and phosphorus (P) atoms scaffolded by rationally designed mesoporous carbon nanospheres (MCNs) with spoke-like nanochannels for boosting ring-opening reaction of epoxide to produce an array of pharmacologically important ß-amino alcohols. Notably, interfacial defects in MCN derived from the use of sacrificial template create abundant unpaired electrons, thereby stably anchoring N and P atoms and in turn Fe atoms on MCN. Importantly, the introduction of P atom promotes the symmetry-breaking of common four N-coordinated Fe sites, resulting in the Fe-N3P sites on MCN (denoted Fe-N3P-MCN) with an asymmetric electronic configuration and thus superior catalytic capability. As such, the Fe-N3P-MCN catalysts manifest a high catalytic activity for ring-opening reaction of epoxide (97% yield) over the Fe-N3P docked on nonporous carbon surface (91%) as well as the sole Fe-N4 SACs grounded on the same MCN support (89%). Density functional theory calculations reveal that Fe-N3P SAC lowers the activation barrier for the C-O bond cleavage and the C-N bond formation, thus accelerating the ring-opening of epoxide. Our study provides fundamental and practical insights into developing advanced catalysts in a simple and controllable manner for multistep organic reactions.

The Application of Digital Technology in the Complex Situation of News Dissemination from the Perspective of New Media Art.

As the continous innovation of new media technology, the media environment of the entire society has undergone profound changes. Digital technology has had a profound impact on the way news is disseminated. It has made a significant impact on the collecting, creation, and distribution of news, as well as the way viewers receive it. As a result, the news media's operation and management style is continually modified. However, in the process of news dissemination, the situations involved are complex and changeable, which leads to different digital technology applications. Aiming at different complex situations in news dissemination under the vision of new media art, this work designs a neural network to optimize the distribution for the required digital technology application schemes. The main work of this paper has the following two points. First, it systematically investigates the current research status of news communication based on digital technology and analyzes the research trends of digital technology and news communication in complex contexts under the vision of new media art. Second, a new neural network is proposed for the optimal application of digital technology for news propagation in different complex situations. This neural network uses an improved particle swarm optimization algorithm and an improved network training strategy to improve the BP network, which can effectively solve the shortcomings of the BP network. A large number of experiments have proved the effectiveness and correctness of this method.

A rare case of male Fournier's gangrene with mixed Actinomyces turicensis infection.

BACKGROUND: Fournier's gangrene (FG), a urological emergency with high mortality, is an infectious necrotizing fasciitis of the perineal and genital regions. The majority of FG is caused by polymicrobial organisms involving mixed aerobes and anaerobes but rarely reveals Actinomyces species. CASE PRESENTATION: We report a healthy 67-year-old Asian male who presented with rapidly progressive painful swelling of the scrotum. Clinically diagnosed with FG, the patient underwent an emergency radical debridement, followed by broad-spectrum antibiotics and negative pressure wound therapy. The identification of the causative microorganisms showed Actinomyces turicensis and the antibiotic treatment was adjusted accordingly. After wound bed preparation, we took split-thickness skin grafts to cover the scrotal wound. Active management to minimize faecal contamination was applied throughout the whole course of treatment and repair. The patient was satisfied with the outcome. This was an extremely rare case of A. turicensis as the main causative pathogen of FG. CONCLUSIONS: FG due to Actinomyces species is rarely reported, but we should still consider this pathogenic microorganism that has long been neglected.

Theory of deep convolutional neural networks III: Approximating radial functions.

We consider a family of deep neural networks consisting of two groups of convolutional layers, a downsampling operator, and a fully connected layer. The network structure depends on two structural parameters which determine the numbers of convolutional layers and the width of the fully connected layer. We establish an approximation theory with explicit approximation rates when the approximated function takes a composite form f∘Q with a feature polynomial Q and a univariate function f. In particular, we prove that such a network can outperform fully connected shallow networks in approximating radial functions with Q(x)=|x|2, when the dimension d of data from Rd is large. This gives the first rigorous proof for the superiority of deep convolutional neural networks in approximating functions with special structures. Then we carry out generalization analysis for empirical risk minimization with such a deep network in a regression framework with the regression function of the form f∘Q. Our network structure which does not use any composite information or the functions Q and f can automatically extract features and make use of the composite nature of the regression function via tuning the structural parameters. Our analysis provides an error bound which decreases with the network depth to a minimum and then increases, verifying theoretically a trade-off phenomenon observed for network depths in many practical applications.

Quantitative assessment of liver function with hepatocyte fraction: Comparison with T1 relaxation-based indices.

PURPOSE: This study aimed to assess the use of hepatocyte fraction in gadoxetic acid-enhanced magnetic resonance imaging (MRI) for quantitatively evaluating the liver function in comparison with T1 relaxation-based indices. METHODS: This retrospective study included 79 patients with chronic liver disease, who were divided into 2 groups based on the results of the indocyanine green retention test (ICG). All patients underwent a gadoxetic acid-enhanced MRI of the liver. Pre- and post-contrast Look-Locker sequences were used 20 min after gadoxetic acid administration to acquire T1 mapping. Two readers independently identified and measured the MRI parameters [five T1 relaxation-based indices (T1pre, T1post, rrT1, R1post/R1pre and ΔR1) and two hepatocyte fraction indices (HeF and KHep)]. An Independent-samples t test was used to compare each parameter for the two groups. Pearson correlation analysis was used to analyze the correction in each parameter and 15-minute ICG retention rate (ICG-R15). Receiver operating characteristic analyses were performed to differentiate the diagnostic performance of each parameter in ICG-R15 ≤ 20 % and ICG-R15 > 20 % groups. RESULTS: T1pre and T1post were significantly lower in the ICG-R15 ≤ 20 % group than in the ICG-R15 > 20 % group (P < 0.05). rrT1, R1post/R1pre, ΔR1, HeF, and KHep were significantly higher in the ICG-R15 ≤ 20 % group than in the ICG-R15 > 20 % group (P < 0.05). The correction coefficients between T1pre, T1post, rrT1, R1post/R1pre, ΔR1, HeF, KHep, and ICG-R15 were 0.343, 0.783, -0.833, -0.781, -0.803, -0.819, and -0.832, respectively. The area under the curves (AUCs) of T1pre, T1post, rrT1, R1post/R1pre, ΔR1, HeF, and KHep in assessing the ICG-R15＞20 % groups were 0.761, 0.945, 0.912, 0.912, 0.948, 0.945, and 0.950, respectively. KHep had the highest AUC, sensitivity, and specificity. CONCLUSION: Hepatocyte fraction based on gadoxetic acid-enhanced T1-mapping MRI is an efficient diagnostic tool for the quantitative evaluation of liver function.

Evaluation of liver function using the hepatocyte enhancement fraction based on gadoxetic acid-enhanced MRI in patients with chronic hepatitis B.

OBJECTIVES: This study aimed to evaluate the feasibility of using the hepatocyte enhancement fraction (HEF) based on gadoxetic acid-enhanced magnetic resonance imaging (MRI) for assessing the liver function in patients with chronic hepatitis B. METHODS: Sixty patients with Child-Pugh grade A (CP-A), 18 with Child-Pugh grade B (CP-B), 2 with Child-Pugh grade C (CP-C), and 20 with normal liver function (NLF) were enrolled. Gadolinium ethoxybenzyldiethy-lenetriaminepentaacetic acid (Gd-EOB-DTPA)-enhanced MRI was conducted. T1 mapping imaging was performed before and 20 min after Gd-EOB-DTPA administration. The pre- and post-contrast T1 values of the liver (T1pre and T1post), increase in the T1 relaxation rate (ΔR1), rate of decrease in the T1 relaxation time (ΔT1), HEF, and uptake coefficient (K) parameters in the NLF, CP-A, and CP-B + CP-C groups were compared using one-way analysis of variance. The effectiveness of each parameter in differentiating the NLF + CP-A group from the CP-B + CP-C group was evaluated using the receiver operating characteristic (ROC) curve. RESULTS: The HEF, K, ΔT1, and ΔR1 values decreased, while the T1post and T1pre values increased, with the increase in liver function damage. Significant differences in T1post, ΔT1, ΔR1, and HEF were found between different groups, except for the CP-A and NLF groups. However, no significant difference was observed in the T1pre among the three groups. HEF exhibited the largest area under the ROC curve. CONCLUSION: The HEF is an effective method for evaluating liver function in patients with hepatitis B.

Negative pressure wound therapy and split thickness skin graft aided in the healing of extensive perineum necrotizing fasciitis without faecal diversion: a case report.

BACKGROUND: Perineum necrotizing fasciitis, also known as Fournier gangrene (FG), is a rare but highly mortal infectious necrotizing fasciitis with or without involvement of the underlying muscle. Evidence exists that negative pressure wound therapy (NPWT) combined with a split thickness skin graft (STSG) can help to heal wounds with FG. However, when the wound spreads to the anal area, it can easily be contaminated by faeces, causing a more extensive wounds; thus, faecal diversion is considered. Here, we report a case of extensive perineum necrotizing fasciitis that spread to near the anus; NPWT combined with STSGs was used to help heal the wound without faecal diversion. CASE PRESENTATION: A 47-year-old male patient was admitted with extensive perineum fascia necrosis caused by Pseudomonas aeruginosa that rapidly spread to near the anus. After comprehensive therapy completed wound bed preparation, STSGs from the scalp were grafted to the wound, and NPWT was applied to improve STSGs survival and seal the anus without faecal diversion. After treatment, graft take was 95%, and the exposed testicular and residual wounds were repaired with a local skin flap. At discharge, the wound had decreased to two pea-sized areas. The patient received conventional moist gauze therapy to close the residual wound at the local hospital. A follow-up by telephone 1 month later showed that both wounds had healed and that the patient was satisfied with the outcome. CONCLUSION: NPWT use combined with STSGs to cover the whole wound and the anus without faecal diversion is a safe and effective method to help with wound healing and avoid contamination with excrement.

Yeast Surface Display of Antheraea pernyi Lysozyme Revealed α-Helical Antibacterial Peptides in Its N-Terminal Domain.

The present study investigated a novel lysozyme ApLyz from the Chinese oak silkmoth, Antheraea pernyi, for its active expression with N- or C-terminus fused to the yeast cell surface, and the antimicrobial activities of the corresponding expressed lysozymes were evaluated. The bactericidal activity of C-terminal fusion of ApLyz surpassed that of the N-terminal fusion, which revealed the implication of an N-terminal stretch of ApLyz in the bactericidal function based on the structural mobility of this region. Two N-terminal peptides of ApLyz (residues 1-15 and 1-32), which primarily consist of amphiphilic α-helices, exerted similar bactericidal efficacy and had a strong preference for the Gram-negative strains. Further investigation revealed that the N-terminal peptides are membrane-targeting peptides causing cell permeabilization and also possess nonmembrane disturbing bactericidal mechanism. Overall, in addition to the key findings of novel bactericidal peptides from silkmoth lysozyme, this work laid the foundation for future improvement of ApLyz by protein engineering.

Trends in unprotected intercourse among heterosexual men before and after brothel ban in Siem Reap, Cambodia: a serial cross-sectional study (2003-2012).

BACKGROUND: Following Cambodia's implementation of the 100% condom use program with enforcement of condom use and STI treatment services for sex workers in 2001, sexually transmitted infection and HIV declined markedly. In 2008, Cambodia implemented a law to ban brothel-based sex work. We reported trends in unprotected vaginal intercourse with sex workers among heterosexual men buying sex before (2003-2008) and after (2009-2012) the brothel ban in Cambodia. We also determined the association of brothel ban with these men's reports of unprotected intercourse with sex workers. METHODS: In this serial cross-sectional study, we collected yearly behavioural data on random cross-sectional samples of heterosexual men buying sex who attended the only government health centre in Siem Reap for voluntary confidential counselling and testing (VCCT) between 2003 and 2012. We used multivariable Poisson regression analysis on the 10-year data of 976 men to obtain the adjusted prevalence ratio (aPR) of unprotected intercourse in the last 6 months by brothel closure. RESULTS: Men buying sex from non-brothel-based sex workers increased almost 3-fold from 17% in 2007-2008 before brothel closure to 55% in 2011-2012 after brothel closure (p < 0.001). Unprotected intercourse with sex workers in the last week increased significantly from 37% (2003-2004) before brothel closure to 65% (2011-2012) after brothel closure. This increase corresponded closely with the increase in self-reported unprotected intercourse from 35% to 61% by the sex workers (n = 1805) attending the same clinic for VCCT. Brothel closure was associated with an increased risk (aPR: 1.65; 95% CI: 1.40-1.94) of unprotected intercourse with sex workers. HIV prevalence in the heterosexual men declined significantly from 26% in 2003-2004 to 4.8% in 2007-2008 and 0 case in 2009-2010 before increasing to 5.6% in 2011-2012. CONCLUSION: Our findings suggest that the brothel ban had led to an increase in unprotected intercourse with all sex workers for men buying sex. This effect could be attributed to reduced condom access, a consequence of the lack of feasibility to implement the 100% condom use program following the brothel ban. The ban on brothels in Cambodia should be reviewed.

The role of postmastectomy radiation therapy in patients with immediate prosthetic breast reconstruction: A meta-analysis.

OBJECTIVE: The controversy remains as to whether immediate prosthetic breast reconstruction with postmastectomy radiation therapy (PMRT) is associated with acceptable complications and aesthetic outcomes. The aim of this meta-analysis was to provide a pooled analysis of comparative clinical studies that evaluated breast cancer patients who were treated with a mastectomy and an immediate prosthetic breast reconstruction to compare the complications and satisfaction of those who underwent or did not undergo PMRT. METHODS: According to the recommendations of the Cochrane Collaboration, we established a rigorous study protocol. We performed a systematic electronic search of the PubMed and Embase databases to identify articles for inclusion in our meta-analysis. Reconstruction failure, overall complications, capsular contracture, and patient satisfaction were analyzed individually. RESULTS: Fifteen controlled trials were included, comprising 5314 patients (1069 PMRT vs 4245 non-PMRT). Primary outcomes revealed a statistically significant increase in overall complications [odds ratio (OR) 3.45; 95% confidence interval (95% CI) 2.62-4.54; P < .00001], reconstruction failure (OR: 2.59; 95% CI 1.46-4.62; P = .001), and capsular contracture (OR: 5.26, 95% CI: 2.73-10.13, P < .00001) after receiving PMRT. CONCLUSION: Our review found that PMRT for patients who underwent immediate implant-based breast reconstruction led to higher risks of reconstruction failure, overall complications, and capsular contracture. However, it is still the standard adjuvant therapy for mastectomy patients who have opted for immediate implant-based breast reconstruction.

[Protective effects of Curcumin analogue L6H4 on kidney from type 2 diabetic rats].

OBJECTIVE: To investigate the protective effect of curcumin analogue L6H4 on the kidney from the type 2 diabetic rats. METHODS: Twenty-four SPF male SD rats were randomly divided into 3 groups(n=8):normal control group(NC),diabetes mellitus group(DM) and DM+L6H4-treatment group(DT). After rats were fed with high-fat diet for 4 weeks, both the DM and DT groups were injected with streptozotocin intraperitoneally to induce type 2 diabetes mellitus models. The rats in DT group were given L6H4 by gavage at the dose of 0.2 mg/kg·d for 8 weeks. After the treatment, the 24 h urinary protein, fasting blood glucose (FBG), triglyceride (TG), serum creatinine(Scr),blood urea nitrogen (BUN) and uric acid (UA) were detected biochemically. The pathological changes of the kidneys were observed under light and transmission electron microscopes. The expressions of TGF-ß1, FN and Col IV were detected by immunohistochemistry. RESULTS: The levels of the 24 h urinary protein, FBG, TG, Scr and BUN were elevated significantly in diabetic group(P<0.01). The glomerular volume of DM group rats became irregularly enlarged, diffused mesangial matrix accumulated, with basal membrane proliferous hypertrophy and fusion phenomenon of foot process, the expressions of TGF-ß1,FN and Col-IV were elevated significantly (P<0.05). After treated with L6H4, the levels of the 24 h urinary protein, FBG, TG, Scr and BUN were decreased in DT group compared to DM group (P<0.01), the morphological changes of kidney were ameliorated. The expression levels of TGF-ß1, FN and Col-IV were downregulated (P<0.05). CONCLUSIONS: L6H4 exerts the protective effect on kidneys of type 2 diabetic rats by reducing expression of TGF-ß1, inhibiting secretion of Col-IV and FN, relieving the deposition of the extracellular matrix.

Carbon Ion Implantation: A Good Method to Enhance the Biocompatibility of Silicone Rubber.

BACKGROUND: Silicone rubber and silicone rubber-based materials have been used as medical tissue implants in the field of plastic surgery for many years, but there are still some reports of adverse reactions to long-term implants. Earlier studies have shown that ion implantation could enhance the biocompatibility of biomaterials. However, whether ion implantation has a good effect on silicone rubber is unknown. METHODS: Three types of carbon ion silicone rubber were obtained by implanting three doses of carbon ions. Then, the antibacterial adhesion properties and the in vivo host responses were evaluated. The antibacterial adhesion properties were examined by plate colony counting, fluorescence staining, and scanning electron microscopic observation. The host responses were evaluated by surveying inflammation and fiber capsule formation that developed after subcutaneous implantation in Sprague-Dawley rats for 7, 30, 90, and 180 days. In addition, the possible mechanism by which ion implantation enhanced the biocompatibility of the biomaterial was investigated and discussed. RESULTS: Carbon ion silicone rubber exhibits less bacterial adhesion, less collagen deposition, and thinner and weaker tissue capsules. Immunohistochemical staining results for CD4, tumor necrosis factor-α, α-smooth muscle actin, and elastin showed the possible mechanism enhancing the biocompatibility of silicone rubber. These data indicate that carbon ion silicone rubber exhibits good antibacterial adhesion properties and triggers thinner and weaker tissue capsules. In addition, high surface roughness and high zeta potential may be the main factors that induce the unique biocompatibility of carbon ion silicone rubber. CONCLUSION: Ion implantation should be considered for further investigation and application, and carbon ion silicone rubber could be a better biomaterial to decrease silicone rubber-initiated complications.

Effect of microtubule-associated protein-4 on epidermal cell migration under different oxygen concentrations.

After skin trauma, regional epidermal cell migration mediates the re-epithelialization of the wound surface, which is an important step for wound healing, yet the underlying molecular regulatory mechanism is unclear. In the current study, HaCaT cells were maintained under different oxygen concentrations (1%, 21%, 40% and 65%). Technologies including immunofluorescence staining, wound scratch, transwell invasion, western blot and low-expression lentiviral vector were utilized to observe the changes in microtubule dynamics and the microtubule-associated protein (MAP)4 expression. MAP4's effect on cell migration under different oxygen concentrations was also studied. The results showed that under hyperoxic (40% and 65%) and hypoxic (1%) conditions, HaCaT cells were able to regulate cell microtubule dynamics by MAP4, thus promoting cell migration. On the other hand, MAP4 silencing through targeted shRNA attenuated HaCaT cell migration under the above oxygen concentrations. These results imply that MAP4 plays an important role in epidermal cell migration under different oxygen concentrations.

High-resolution non-contact measurement of the electrical activity of plants in situ using optical recording.

The limitations of conventional extracellular recording and intracellular recording make high-resolution multisite recording of plant bioelectrical activity in situ challenging. By combining a cooled charge-coupled device camera with a voltage-sensitive dye, we recorded the action potentials in the stem of Helianthus annuus and variation potentials at multiple sites simultaneously with high spatial resolution. The method of signal processing using coherence analysis was used to determine the synchronization of the selected signals. Our results provide direct visualization of the phloem, which is the distribution region of the electrical activities in the stem and leaf of H. annuus, and verify that the phloem is the main action potential transmission route in the stems of higher plants. Finally, the method of optical recording offers a unique opportunity to map the dynamic bioelectrical activity and provides an insight into the mechanisms of long-distance electrical signal transmission in higher plants.

Efficient heralding of O-band passively spatial-multiplexed photons for noise-tolerant quantum key distribution.

When implementing O-band quantum key distribution on optical fiber transmission lines carrying C-band data traffic, noise photons that arise from spontaneous Raman scattering or insufficient filtering of the classical data channels could cause the quantum bit-error rate to exceed the security threshold. In this case, a photon heralding scheme may be used to reject the uncorrelated noise photons in order to restore the quantum bit-error rate to a low level. However, the secure key rate would suffer unless one uses a heralded photon source with sufficiently high heralding rate and heralding efficiency. In this work we demonstrate a heralded photon source that has a heralding efficiency that is as high as 74.5%. One disadvantage of a typical heralded photon source is that the long deadtime of the heralding detector results in a significant drop in the heralding rate. To counter this problem, we propose a passively spatial-multiplexed configuration at the heralding arm. Using two heralding detectors in this configuration, we obtain an increase in the heralding rate by 37% and a corresponding increase in the heralded photon detection rate by 16%. We transmit the O-band photons over 10 km of noisy optical fiber to observe the relation between quantum bit-error rate and noise-degraded second-order correlation function of the transmitted photons. The effects of afterpulsing when we shorten the deadtime of the heralding detectors are also observed and discussed.

Transmission of O-band wavelength-division-multiplexed heralded photons over a noise-corrupted optical fiber channel.

We transmitted O-band heralded photons over 10 km of optical fiber in a proof-of-concept experiment demonstrating the feasibility of using heralded photons to improve the noise tolerance of quantum key distribution. In our experiment, the optical fiber channel was corrupted by noise photons to the extent that if we had used an attenuated laser as the photon source, a photon signal-to-noise ratio of < 4.0 at the receiver, corresponding to a quantum bit-error rate of > 10.0%, would have prevented the effective generation of secure keys. Using a photon heralding scheme, the photon signal-to-noise ratio in our experiment was shown to be > 7.8. This corresponds to a quantum bit-error rate of < 5.7%, which is good enough for distilling secure keys. In addition, we showed that it is possible to incorporate wavelength-division-multiplexing into the photon heralding scheme to improve overall key rate. We discussed and clarified the prospects and limitations of the photon heralding scheme for noise-tolerant quantum key distribution.