A PML method for signal-propagation problems in axon

This work is focused on the modelling of signal propagations in myelinated axons to characterize the functions of the myelin sheath in the neural structure. Based on reasonable assumptions on the medium properties, we derive a two-dimensional neural-signaling model in cylindrical coordinates from the time-harmonic Maxwell's equations. The well-posedness of model is established upon Dirichlet boundary conditions at the two ends of the neural structure and the radiative condition in the radial direction of the structure. Using the perfectly matched layer (PML) method, we truncate the unbounded background medium and propose an approximate problem on the truncated domain. The well-posedness of the PML problem and the exponential convergence of the approximate solution to the exact solution are established. Numerical experiments based on finite element discretization are presented to demonstrate the theoretical results and the efficiency of our methods to simulate the signal propagation in axons

Analysis on Impact of Land Use Change on Urban Waterlogging Caused by Floods

In recent years, ultra-high-intensity rainfall at home and abroad has caused frequent urban waterlogging disasters, posing a severe threat to people’s lives, property and city’s safety. Based on the satellite image data of Shanghai Waigaoqiao Free Trade Zone in different periods and the Storm Water Management Model (SWMM), this paper establishes a model of heavy rainfall under the underlying surface of a complex city, and analyses topographic features, different land use types, rainfall infiltration intensity and the characteristics of the drainage pipe network. The rainwater accumulation under different rainstorms and urbanization levels is simulated and analysed. The research results show that urban rainstorm accumulation is closely related to land use changes. With the increase of surface impermeability and rainfall intensity, the risk of waterlogging in the study area tends to increase: From 1994 to 2019, the construction area has increased from 2.5096km2 to 5.8662km2 in the study area. Compared with 1994, under the same rainfall conditions, the simulated flooding node and runoff coefficient in 2019 both increased significantly

Imaging Diagnosis and Interventional Treatment for Hepatocellular Carcinoma Combined with Arteriovenous Fistula

In order to explore the imaging diagnosis methods and interventional treatment effects of hepatocellular carcinoma combined with hepatic arteriovenous fistula (HAVF), a total of 120 patients, who were diagnosed as hepatic carcinoma with arteriovenous shunting and underwent medical imaging diagnosis and interventional surgery therapy at a designated hospital by this study from December 2014 to December 2018, were chosen as study subjects. Digital subtraction angiography was performed to analyze the imaging features of hepatocellular carcinoma combined with HAVF in each patient; then, according to these imaging diagnosis results, gelatin sponge or coil was used to block the fistula; mitomycin, carboplatin powder, and lipiodol mixed emulsion was combined or separately utilized for hepatic tumor embolization, in which iodized oil embolization chemotherapy was used for patients with mild paralysis; gelatin sponge granule embolization chemotherapy was used for moderate paralysis patients at their first intervention, and, after about 1 month, if the sputum disappeared, iodized oil embolization was used again; and hepatic arterial infusion chemotherapy was used only for patients with severe paralysis. The results show that the central type of HAVF is characterized by early angiography of portal vein and large branches and tumor staining after portal vein’s angiography; the peripheral type of HAVF is characterized by portal vein branching in hepatic tumor and double rail sign accompanied by the arterial branch; 112 cases of patients completed embolization chemotherapy; 8 cases of patients only received chemotherapy perfusion; in 109 cases of patients sputum disappeared or shunt decreased at first treatment; and in 113 cases of patients iodine oil was well deposited or the tumor was stably reduced; most of the symptoms of refractory ascites, diarrhea, and upper gastrointestinal bleeding were controlled or improved, and there were no complications such as pulmonary embolism and hepatic failure. Therefore, HAVF increases the difficulty of interventional therapy, but, as long as the positive and appropriate treatment measures are taken, it can still achieve better curative effect without serious complications, which can effectively alleviate the clinical symptoms of patients and improve the quality of life of patients. The results of this study provide a reference for the further researches on imaging diagnosis and interventional treatment for hepatocellular carcinoma combined with arteriovenous fistula

Simultaneous Estimation of a Contaminant Source and Hydraulic Conductivity Field by Combining an Iterative Ensemble Smoother and Sequential Gaussian Simulation

Joint estimation of groundwater contaminant source characteristics and hydraulic conductivity is of great significance for contaminant transport models in heterogeneous subsurface media. As for accurate characterization of hydraulic conductivities, both geostatistical modeling and groundwater inverse modeling are alternative approaches. In this study, an iterative ensemble smoother and sequential gaussian simulation (SGSIM) in geostatistics modeling were combined to realize the simultaneous inversion of contaminant sources and hydraulic conductivities, by using directly measured hydraulic conductivities and indirect hydraulic head and concentration data. To alleviate the high computational cost caused by repetitive evaluations of complex, high-dimensional groundwater models, SGSIM with the pilot points method was used. Considering the characteristics of the proposed method, four scenarios with ten cases were set up in terms of ensemble number and iteration number that affect the performance of the iterative ensemble smoother, the number of pilot points, and the observation data, respectively. The results for the synthetic example indicate that the ensemble size of 2000 and the pilot point number of 80 is an ideal combination of parameters, and the proposed method can successfully recover contaminant source information simultaneously with hydraulic conductivity

Simultaneous Estimation of a Contaminant Source and Hydraulic Conductivity Field by Combining an Iterative Ensemble Smoother and Sequential Gaussian Simulation

Joint estimation of groundwater contaminant source characteristics and hydraulic conductivity is of great significance for contaminant transport models in heterogeneous subsurface media. As for accurate characterization of hydraulic conductivities, both geostatistical modeling and groundwater inverse modeling are alternative approaches. In this study, an iterative ensemble smoother and sequential gaussian simulation (SGSIM) in geostatistics modeling were combined to realize the simultaneous inversion of contaminant sources and hydraulic conductivities, by using directly measured hydraulic conductivities and indirect hydraulic head and concentration data. To alleviate the high computational cost caused by repetitive evaluations of complex, high-dimensional groundwater models, SGSIM with the pilot points method was used. Considering the characteristics of the proposed method, four scenarios with ten cases were set up in terms of ensemble number and iteration number that affect the performance of the iterative ensemble smoother, the number of pilot points, and the observation data, respectively. The results for the synthetic example indicate that the ensemble size of 2000 and the pilot point number of 80 is an ideal combination of parameters, and the proposed method can successfully recover contaminant source information simultaneously with hydraulic conductivity

Effect of acid treatment on catalytic performance of FeN/ZIF-8 catalyst for oxygen reduction reaction

The development of non-noble metal catalysts with high-performance and low-cost for oxygen reduction reaction is one of the main research directions in proton exchange membrane fuel cells.The catalytic performance of the FeN/ZIF-8 catalysts was investigated using ZIF-8, 1, 10-phenanthroline and FeSO4·7H2O as carbon support, nitrogen and iron precursor, respectively. The effects of acid treatment on structure and catalytic performance of FeN/ZIF-8 catalyst were also explored by various techniques. The structure of catalysts was characterized by X-ray diffraction, specific surface area and pore size distribution measurements and transmission electron microscopy, etc. The catalytic activity and stability of the catalysts for oxygen reduction reaction were investigated by linear sweep voltammetry and accelerated degradation test. The results show that the catalysts with ZIF-8 as the carbon support have high initial catalytic activity for oxygen reduction reaction due to their high specific surface area and the existence of Fe3C in catalysts. The acid treatment can remove some unstable iron-containing carbides and disorder carbon in the catalyst. The structure of the FeN/ZIF-8-A catalyst is modified by acid treatment. The higher specific surface area, more abundant mesoporous structure and higher pore volume, as well as the improved resistance to corrosion in acid solution are the key reasons of FeN/ZIF-8-A catalyst with better catalytic activity and stability for oxygen reduction reaction in acid environment

Multi-dimensional dynamic simulation of rainstorm waterlogging in urban communities

One major threat to cities at present is the increasing rainstorm waterlogging hazards due to climate change and accelerated urbanization. This paper explores the mechanism of rainstorm waterlogging and enables the fine simulation of surface water propagation over complex urban terrain. A novel community-scale waterlogging modeling scheme is presented by loosely coupling a one-dimensional sewer model with a two-dimensional overland model under an open-source framework. The coupled model was applied to Waigaoqiao Free Trade Zone located in Pudong New Area of Shanghai. To quantify the influence of rainfall intensity and drainage conditions on the waterlogging, 12 scenarios were constructed by combining four rainfall return periods (3, 5, 10, and 20 a) and three startup water depths (1.5, 2.0, and 2.5 m) of pump stations. The multi-scenario simulation results show that the waterlogging risk increases from north to south in the study area, and that risk zones with water depth above 0.3 m are mostly concentrated in the southwest and southeast corners of the site. The longer the rainfall return period, the larger the submerged area, and the spatial distribution of surface water accumulation is affected by local topography and drainage system. In addition, reducing the startup water depth of pump stations has an obvious effect on inhibiting the severity of water accumulation. The results provide insights into overland flow across an urban area with densely populated buildings and help to reduce the risk of rainstorm-induced waterlogging disasters

A Generalization of the Drainage Capacity in Data-Scarce Urban Areas: An Improved Equivalent Infiltration Method

This article addresses the challenge of simulating rainstorm waterlogging in urban-scale areas where reliable drainage pipe network data are often lacking. Although methods have been developed to tackle this issue, there remains a gap in their effectiveness. We present a novel approach, the modified equivalent infiltration (MEI) method, by building upon the foundation of the Equivalent Infiltration (EI) method. This study focuses on the outer ring area of Shanghai, utilizing data from the “In-Fa” typhoon period for simulation and comparison. Our findings reveal that the MEI method, requiring the same data inputs as the EI method, surpasses its predecessor in both principle and simulation results. Additionally, the MEI method demonstrates robustness in handling rainstorm waterlogging scenarios

Safety and efficacy of camrelizumab combined with radiotherapy as neoadjuvant therapy for locally advanced esophageal squamous cell carcinoma: a prospective single-arm phase II clinical trial protocol

Abstract Background Neoadjuvant chemoradiotherapy followed by esophagectomy is the standard of care for locally advanced esophageal squamous cell carcinoma (ESCC). However, approximately 30% of patients still develop distant metastases and have a high incidence of treatment-related adverse events. Immunotherapy, as a new modality for anti-cancer treatment, has shown promising clinical benefits for patients with ESCC. The synergistic effects of immunotherapy and radiotherapy make their combination promising as neoadjuvant treatment for locally advanced ESCC. Methods All participants who meet the inclusion criteria will be enrolled after signing the informed consent form. Patients with thoracic segment esophageal cancer with clinical stage T2–3 N0 M0 or T2–3 N + M0 will be included. A total of 25 patients are to be recruited for the study. Twelve patients will be recruited in phase I, with at least two achieving major pathological response (MPR) before entering phase II. They will be treated with radical surgery within 4–8 weeks after the completion of two cycles of neoadjuvant radiotherapy in combination with camrelizumab according to the study schedule. The primary endpoint is the major pathological remission rate of all per-protocol patients. The secondary endpoints are the R0 resection rate, pathological complete remission rate, and adverse events. The interim analysis will be conducted after 12 patients have been enrolled. The trials will be terminated when more than two treatment-related deaths occur or fewer than five patients have major pathological remission. Discussion We designed this prospective single-arm phase II clinical study to evaluate the combination of camrelizumab and standard radiotherapy as preoperative neoadjuvant therapy for patients with resectable ESCC as part of the quest for better treatment options for patients with locally advanced ESCC. Trial registration This trial protocol has been registered on the NIH Clinical Trials database ( www.clinicaltrials.gov/ , NCT05176002. Registered on 2022/01/04). The posted information will be updated as needed to reflect protocol amendments and study progress

The Clinical Characteristics, Treatments and Prognosis of Post-Esophagectomy Airway Fistula: A Multicenter Cohort Study

BACKGROUND: Post-esophagectomy airway fistula (PEAF) is a serious complication after esophageal cancer resection. At present, the clinical characteristics, treatments and prognosis of PEAF patients remain inconclusive. We aimed to investigate these problems of patients with PEAF through a multi-center retrospective cohort study. METHODS: We included consecutive patients who underwent esophagectomy for esophageal cancer in seven major Chinese esophageal cancer centers from January 2010 to December 2020. Based on the anatomic characteristics of PEAF patients, PEAFs were divided into Union type I (without digestive fistula) and Union type II [respiratory-digestive fistula (RDF)], and subtypes a and b (tracheal or bronchial fistulas), as well as L1 and L2 (same or different level of fistulas). The clinical characteristics, diagnoses, managements, and effects of the various types were retrospectively analyzed. RESULTS: PEAF occurred in 85 of 26,608 patients (0.32%), including eight females and 77 males. There were 16 patients with type I and 69 with type II. The numbers of healings, non-healings, and deaths at discharge were 45 (52.9%), 20 (23.5%), and 20 (23.5%), respectively. Type Ib was common in type I, and type II L1 was common in type II. The healing rates of surgical, stent, and conservative treatments were 50%, 60%, and 50%, respectively. All type I patients treated with stent implantation were healed at discharge. The healing rates, mortality, and 3-year survival of type II L1 and type II L2 patients were 55.4% and 30.8%, 17.9% and 30.8%, and 34.3% and 15.4%, respectively. The 5-year survival rates of all PEAFs were 21.1%. CONCLUSIONS: PEAF is an infrequent and life-threatening complication after esophagectomy. Patients with different types of PEAF often have different inducements. In this study, we found that the healing rates of surgical and conservative treatments were similar, and stent implantation may have the potential to improve efficacy. Type II L2 patients were the most difficult to cure