A CCBM-based generalized GKB iterative regularizing algorithm for inverse Cauchy problems

This paper examines inverse Cauchy problems that are governed by a kind of elliptic partial differential equation. The inverse problems involve recovering the missing data on an inaccessible boundary from the measured data on an accessible boundary, which is severely ill-posed. By using the coupled complex boundary method (CCBM), which integrates both Dirichlet and Neumann data into a single Robin boundary condition, we reformulate the underlying problem into an operator equation. Based on this new formulation, we prove the existence of a unique solution even in cases with noisy data. A Golub-Kahan bidiagonalization (GKB) process together with Givens rotation is employed for iteratively solving the proposed operator equation. The regularizing property of the developed method, called CCBM-GKB, and its convergence rate results are proved under a posteriori stopping rule. Finally, a linear finite element method is used for the numerical realization of CCBM-GKB. Various numerical experiments demonstrate that CCBM-GKB is a kind of accelerated iterative regularization method, as it is much faster than the classic Landweber method

FDMA Point-to-Multi-Point Fibre Access System for Latency Sensitive Applications

We present a demo for a multiple uplink access system with real-time services. Several terminals transmit and are detected simultaneously through FDMA. The system can allow latency-sensitive and best-effort applications to share the network

FDMA in Point-to-Multipoint Fibre Access Systems for Non-Residential Applications

Optical access networks are seeing growing applications for use cases beyond residential, for example in campus and as Industry 4.0 intra-factory networks, which introduce different requirements in terms of bandwidth delivery and latency. We present an uplink access system with simultaneous transmission and detection of several users by means of frequency division multiplexing (FDM). We demonstrate a multiple uplink access system with differential binary phase shift keying (DBPSK) signals and coherent detection that targets a low and deterministic latency. We achieve receiver (Rx) sensitivities of -43.5dBm, -40dBm, and -34dBm at a pre forward error correction (FEC) bit error ratio (BER) of 10 -3 at 2.5 GBaud, 5 GBaud, and 8 GBaud respectively after 20km of fibre with coherent detection. Furthermore, we show the possibility of employing time-division multiplexing (TDM) within the frequency bands. We also present real-time services showing that the system can allow latency-sensitive and best-effort applications to share the network

Synthesis of carbon-supported PdSn–SnO2 nanoparticles with different degrees of interfacial contact and enhanced catalytic activities for formic acid oxidation

The conjunction of the PdSn alloy and SnO2 is of interest for improving catalytic activity in formic acid oxidation (FAO). Here, we report the synthesis of PdSn–SnO2 nanoparticles and a study of their catalytic FAO activity. Different degrees of interfacial contact between SnO2 and PdSn were obtained using two different stabilizers (sodium citrate and EDTA) during the reduction process in catalyst preparation. Compared to the PdSn alloy, PdSn–SnO2 supported on carbon black showed enhanced FAO catalytic activity due to the presence of SnO2 species. It was also found that interfacial contact between the PdSn alloy and the SnO2 phase has an impact on the activity towards CO oxidation and FAO.Web of Scienc

Nanoparticulate TiO2-promoted PtRu/C catalyst for methanol oxidation: TiO2 nanoparticles promoted PtRu/C catalyst for MOR

To improve the electrocatalytic properties of PtRu/C in methanol electrooxidation, nanoparticulate TiO2-promoted PtRu/C catalysts were prepared by directly mixing TiO2 nanoparticles with PtRu/C. Using cyclic voltammetry, it was found that the addition of 10 wt% TiO2 nanoparticles can effectively improve the electrocatalytic activity and stability of the catalyst during methanol electro-oxidation. The value of the apparent activation energy (Ea) for TiO2-PtRu/C was lower than that for pure PtRu/C at a potential range from 0.45 to 0.60 V. A synergistic effect between PtRu and TiO2 nanoparticles is likely to facilitate the removal of CO-like intermediates from the surface of PtRu catalyst and reduce the poisoning of the PtRu catalysts during methanol electrooxidation. Therefore, we conclude that the direct introduction of TiO2 nanoparticles into PtRu/ C catalysts offers an improved facile method to enhance the electrocatalytic performance of PtRu/C catalyst in methanol electrooxidation.Web of Scienc

CNx-modified Fe3O4 as Pt nanoparticle support for the oxygen reduction reaction

A novel electrocatalyst support material, nitrogendoped carbon (CNx)-modified Fe3O4 (Fe3O4-CNx), was synthesized through carbonizing a polypyrrole-Fe3O4 hybridized precursor. Subsequently, Fe3O4-CNx-supported Pt (Pt/Fe3O4-CNx) nanocomposites were prepared by reducing Pt precursor in ethylene glycol solution and evaluated for the oxygen reduction reaction (ORR). The Pt/Fe3O4-CNx catalysts were characterized by X-ray diffraction, Raman spectra, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. The electrocatalytic activity and stability of the as-prepared electrocatalysts toward ORR were studied by cyclic voltammetry and steady-state polarization measurements. The results showed that Pt/ Fe3O4-CNx catalysts exhibited superior catalytic performance for ORR to the conventional Pt/C and Pt/C-CNx catalysts.Web of Scienc

Improving Rail Station Access with Feeder Bus Network Optimization and Mode Shifts

Because of financial constraints, many transit agencies are trying to balance their budgets and provide an efficient transit network and services. This paper presents an improved model for feeder bus network development problems. The proposed approach consists of three main components: (a) an initial solution generation procedure, (b) a network features determination procedure, and (c) a solution search procedure. The tabu search is used as a metaheuristic method in the solution search procedure to find an optimal solution according to a given set of feasible solutions. The input for the new feeder bus network development problem includes the street network, demands from origins to the suburban rail station, and related parameters. The output demonstrates an optimized feeder bus network system and service frequencies for each route. The results show that the proposed method can be used by transit planners to optimize feeder bus systems that provide access to rail stations and other activity centers

Dexmedetomidine reduces neuropathic pain in a rat model of skin/muscle incision and retraction

Dexmedetomidine has been proposed as a novel anesthetic adjuvant. However, it remains unclear whether peripheral administration of dexmedetomidine is safe and effective to reduce acute postoperative pain. This study aimed to examine the effects of dexmedetomidine on neuropathic pain. Adult male Sprague-Dawley rats were anaesthetized and randomly allocated into four groups (n = 8): Groups S, R, RD1, and RD5 were injected with saline, 0.5% ropivacaine, 0.5% ropivacaine combined with 1 μg dexmedetomidine, and 0.5% ropivacaine combined with 5 μg dexmedetomidine, respectively, around the saphenous nerve. Then, the rats were subjected to skin/muscle incision and retraction (SMIR) surgery in the medial thigh. Mechanical and heat sensitivity was evaluated and morphology of the dorsal root ganglion (DRG) neurons was observed by electron microscopy. Some 62.5%, 50%, 12.5%, and 25% of rats developed mechanical hypersensitivity in Groups S, R, RD1, and RD5, respectively. The number of swollen mitochondria in DRG neurons was significantly more in Group S (257.2 ± 60.9) and Group R (291.6 ± 82.1) than in Group RD1 (97.2 ± 33.3) and Group RD5 (13.6 ± 17.9). In addition, the edema in endoplasmic reticulum and Golgi apparatus was decreased in Group RD1 and Group RD5 compared with Group S and Group R. Peripheral administration of dexmedetomidine improves mechanical and heat hyperalgesia and mitigates postoperative pain

Identification of a novel gene expression signature as prognostic biomarker for human papillomavirus negative head and neck carcinoma

Abstract Purpose Head and neck squamous cell carcinomas (HNSCCs) are heterogeneous and complex malignancies. The present study aimed to explore potential molecular classifications and establish promising prognostic candidate biomarkers for human papillomavirus (HPV)‐negative HNSCC. Methods We performed unsupervised clustering in HPV‐negative patients from the TCGA‐HNSCC database and identified molecular subclusters based on HNSCC prognosis. Weighted gene co‐expression network analysis was used to identify cluster‐related gene modules and identify reliable candidate genes. Biomarker signature was established from these candidate genes via 10‐fold cross validation in a least absolute shrinkage and selection operator (LASSO) Cox regression model and validated in The Cancer Genome Atlas Program (TCGA) cohort and four external Gene Expression Omnibus (GEO) validation cohorts. Results We identified three molecular subclusters (C1–C3), and tumour microenvironment and survival evaluation results showed that C3 had high immune cell infiltration and better prognosis. However, C1 and C2 had low immune cell infiltration, and C1 had a worse survival outcome. A 20‐gene signature was established from the input candidate genes via 10‐fold cross validation in the LASSO Cox regression model. The signature was first validated in a training cohort, followed by a testing cohort and the entire cohort. A total of 347 patients from four external GEO validation cohorts indicated great performance of the signature in predicting outcomes. Conclusion Compared with HPV‐positive patients, those with HPV‐negative HNSCC had an immunosuppressed tumour microenvironment. The 20‐gene signature was developed based on the characteristic unsupervised clustering molecular subclusters to predict survival outcomes in patients with HPV‐negative HNSCC