Topological properties of tetratomic Su-Schrieffer-Heeger chains with hierarchical long-range hopping

We propose a new generalized Su–Schrieffer–Heeger model with hierarchical long-range hopping based on a onedimensional tetratomic chain. The properties of the topological states and phase transition, which depend on the cointeraction of the intracell and intercell hoppings, are investigated using the phase diagram of the winding number. It is shown that topological states with large positive/negative winding numbers can readily be generated in this system. The properties of the topological states can be verified by the ring-type structures in the trajectory diagram of the complex plane. The topological phase transition is strongly related to the opening(closure) of an energy bandgap at the center(boundaries) of the Brillouin zone. Finally, the non-zero-energy edge states at the ends of the finite system are revealed and matched with the bulk–boundary correspondence.

面向社交距离检测的深度学习方法设计与性能验证

对社交距离进行准确检测在传染病溯源、安防监控等领域都有着重大意义。行人间的遮挡会极大降低社交距离检测方法的精度和泛化能力,针对这一问题,该文研究一种遮挡条件下的社交距离检测方法,并验证方法的环境适应性。该方法首先采用简单在线实时跟踪方法(Simple online and realtime track,SORT)进行人员追踪,然后基于单目视觉测距方法来测量行人间距;最后,验证检测方法在不同拍摄视角及人流密度下的泛化性能。研究结果表明,该实验可以在遮挡条件下进行较好的实时追踪,在摄像头的拍摄高度在12 m左右时获取最优的密接行为识别性能,识别准确率为92%。

基于改进LRCN模型的驾驶行为图像序列识别方法

针对汽车安全辅助驾驶技术中驾驶行为识别精度低、收敛速度慢等问题,提出了一种基于改进LRCN模型的驾驶行为图像序列识别方法.采用自建驾驶行为数据集作为输入样本,经过金字塔降采样和高斯混合模型特征提取等预处理算法,得到标准视频图像序列,此序列传入以卷积神经网络和门控递归单元为基础搭建的网络模型做最优化处理,最终完成结果收敛.该模型使用Keras框架在GPU上计算,分别进行了环境适应性试验、预处理算法试验和模型对比试验.结果表明:预处理算法保证了模型的收敛,提高了模型对不同场景、不同测试对象识别的鲁棒性;在自建数据集上该模型的平均识别精度达94.3%,比传统LRCN模型高4.7%,且模型收敛的速度更快,泛化能力更强.

钢/铝激光焊接接头性能与金属间化合物延/脆性的第一性原理和实验研究

采用扫描电子显微镜、能谱仪、X射线衍射仪以及第一性原理计算方法,研究钢/铝激光焊接形成的金属间化合物(IMCs)的形貌、分布、相组成、形成能力、结构稳定性和本征力学性质。结果发现,脆性Fe−Al化合物限制钢/铝接头力学性能,其脆性电子结构根源在于Al(s)、Al(p)和Fe(d)之间的轨道杂化;添加中间夹层可改善钢/铝接头的力学性能,归因于形成的金属间化合物电子结构的改变;金属间化合物由脆性向延性的转变机制主要归因于夹层元素吸引电子的能力弱。钢/铝焊接头的力学性能与金属间化合物的延/脆性密切相关,添加Ti箔有效提高接头的力学性能,表明实验验证与理论计算预测吻合较好。

以W取代Re对γ'-Ni_(3)Al相位错滑移调制蠕变的影响

γ'-Ni_(3)Al相在高温下的反常流变行为与1/2<110>{111}超级部分位错的交滑移密切相关。沿最低能量路径获得的广义堆垛层错能曲线(即Γ面)可以提供大量有关位错形核和运动的信息。采用第一性原理计算,研究Re、W、Mo、Ta、Ti单掺杂与双掺杂对γ'-Ni_(3)Al相Γ面和理想剪切强度τ_(max)的影响。与Re掺杂的情形类似,W在堆垛层错处的Suzuki偏聚可阻止1/6<112>{111}Shockley部分位错的运动和促进1/2<110>{111}超级部分位错的交滑移。当Re被W部分取代时,γ_(APB)^(111)/γ_(APB)^(001)的降低表明γ'相在高温下的反常流变行为不如双Re掺杂,但τ_(max)的增加却表明镍基单晶高温合金的蠕变断裂强度在一定程度上可从中受益,尤其是Re和W在Al−Al位的共偏聚。当点缺陷X1_(Al)和X2_(Al)之间的相互作用采用关联能函数ΔE^(X1_(Al)+X2_(Al))(d)来表征时,无论是吸引还是排斥,强关联都不利于γ'相屈服强度的提高。

基于YOLO模型的红外图像行人检测方法

针对基于传统特征提取方法的远红外图像行人检测存在准确率和实时性不足的问题,本文研究了一种基于改进YOLO模型的远红外行人检测方法,通过改进其深度卷积神经网络的输入分辨率,然后在基于实际道路采集的红外数据集上进行训练,得到检测效果最佳的检测模型,并提出基于车速的自适应图像分辨率模型,以提高车载系统的行人检测性能。在基于实际道路的红外数据集上的对比实验表明,该方法与传统方法相比,准确率从76. 5%提高到89. 2%,每秒传输帧数从0. 01259 f/s提高到40. 5 f/s,满足车载情况下的实时性需求。

基于EMFi薄膜的动态足底压力测量系统

为测量与分析运动员运动过程中动态足底压力变化,优化训练模式与避免其运动损伤,该文研制了一种新型可穿戴式动态足底压力测量系统。以压电驻极体薄膜(EMFi)为传感材料,采集足底16个点的压力信号,原始电荷信号经过高速模拟开关、电荷放大电路、低通滤波放大电路、工频滤波电路、STM32F4内部A/D采集,并由2.4GHz无线发送至上位机。实验结果显示,该系统测试结果与人体正常运动步态变化趋势一致,且具有良好的动态响应和可靠性,为运动员的姿态矫正提供了理论依据。

Stabilization of low-valence transition metal towards advanced catalytic effects on the hydrogen storage performance of magnesium hydride

Magnesium hydride(MgH_(2))has been widely regarded as a potential hydrogen storage material owing to its high gravimetric and volumetric capacity.Its sluggish kinetics and high activation energy barrier,however,severely limit its practical application.Transition metal oxides(TMOs)have been extensively used as catalysts to improve the hydrogen storage performance of MgH_(2),but the low-valence transition metal(TM)ions,resulting from the reduction of TMOs accompanied by the formation of inactive Mg O,have been demonstrated to be the most effective components.Herein,we theoretically and experimentally confirm that the doping of low-valence TMs into Mg O could effectively weaken the Mg-H bonds and decrease the energy required for hydrogen desorption from MgH_(2),leading to superior catalytic activity compared to both TMOs and Mg O.In particular,the apparent activation energy for the dehydrogenation of Mg(Nb)O-catalyzed MgH_(2)could be reduced to only 84.1 kJ mol^(-1),and the reversible capacity could reach around 7 wt.%after 5 cycles with a capacity retention of 96%.Detailed theoretical calculations confirm that the remarkable orbital hybridization between Mg(Nb)O and MgH_(2)promotes charge transfer from MgO to the MgH_(2)monomer,resulting in significantly weakened stability of MgH_(2),which could effectively enhance its hydrogen storage performance.

Efficacy and Safety of Washed Microbiota Transplantation to Treat Patients with Mild-to-Severe COVID-19 and Suspected of Having Gut Microbiota Dysbiosis: Study Protocol for a Randomized Controlled Trial

Objective:Coronavirus disease 2019(COVTD-19)is often accompanied by gastrointestinal symptoms,which are related to gut microbiota dysbiosis(GMD).Whether washed microbiota transplantation(WMT)is an effective treatment for COV1D-19 patients suspected of having GMD by restoring the gut microbiota is unknown.This study is designed to explore the efficacy and safety of WMT in COVID-19 patients suspected of having GMD.Methods:This is a randomized,multicenter,single-blind prospective study.COVID-19 patients suspected of having GMD will be randomly divided to receive routine treatment only or to receive routine treatment and WMT.The frequency of WMT will be once a day for three consecutive days.Laboratory and imaging examinations will be performed at admission,1 and 2 weeks after treatment,and on the day of discharge.Then a telephone follow-up will be conducted at 1st week,2nd week,and 6th month after discharge.The clinical efficacy and safety of WMT in COVD-19 patients suspected of having GMD and the effects of WMT on the organ function,homeostasis,inflammatory response,intestinal mucosal barrier function,and immunity of the patients will be evaluated.Results:By following the proposed protocol,WMT is expected to be efficacious and safe for the treatment of COVID-19 patients suspected of having GMD,and the therapeutic effect is expected to be associated with improvement of the intestinal mucosal barrier function,inflammatory response,and immunity.Conclusion:The findings from this study may offer a new approach for the prevention and treatment of COVID-19 patients suspected of having GMD.

Multiline treatment of advanced squamous cell carcinoma of the lung: A case report and review of the literature

BACKGROUND Squamous cell carcinoma (SCC) is one the most common subtypes of non-small cell lung cancer, yet the treatment options for it remain limited. Here, we report a case of advanced SCC and review the related literature focusing on the multiline therapy method. CASE SUMMARY We report the case of a 45-year-old man with advanced SCC who was deemed inoperable at the time of advanced SCC diagnosis. The patient had been referred to our hospital in April 2013 with complaints of a stuffy feeling in the chest, dyspnea, and pain in the right shoulder lasting for 1 mo. Physical examination found no obvious abnormalities, except for lower breath sound in the right lower lung. Laboratory data were within normal limits. Immunohistochemistry analysis of the tumor tissue showed CK5/6 (+), p63 (+), CD56 (+), and Ki-67 (+, approximately 30%), and genetic testing detected no EGFR mutation. He received a multiline treatment that included chemotherapy, radiotherapy, targeted therapy, and antiangiogenic therapy. After more than 5-year comprehensive treatment, the patient remains alive. CONCLUSION This typical case highlights the importance of appropriate multiline therapy for those patients with advanced SCC.

Nutritional status changes in patients with advanced non-small cell lung cancer receiving first-line chemotherapy

Objective This study aimed to assess the real-life nutritional status changes and gastrointestinal symptoms in patients with advanced non-small cell lung cancer(NSCLC) receiving chemotherapy.Methods A total of 104 patients with metastatic NSCLC receiving first-line chemotherapy were included in this study. Unintentional weight loss, body mass index(BMI) changes, and gastrointestinal symptoms were recorded and evaluated. Biochemical parameters [hemoglobin(Hb) and albumin levels] were compared before and after two chemotherapy cycles using SPSS software.Results Of these patients, 65.38%(68/104) experienced unintentional weight loss, whereas 30.77% and 12.5% presented with ≥ 5% and ≥ 10% degrees of weight loss, respectively, within 6 months before first-line chemotherapy was administered. Then, 48.08%(50/104) of the patients experienced unintentional weight loss after two chemotherapy cycles. The mean body weight after chemotherapy was 61.47 ± 10.37 kg, which was significantly decreased relative to that before chemotherapy(P < 0.05). The mean BMI after chemotherapy was 22.66 ± 3.34 kg/m^2, which was also significantly diminished with respect to that during the previous chemotherapy cycle(P < 0.05). The most common gastrointestinal symptoms reported among all the study patients were anorexia(80/104, 76.92%), nausea(53/104, 50.96%), constipation(49/104, 47.12%), vomiting(48/104, 46.15%), taste disorders(40/104, 38.46%), and early satiety(32/104, 30.77%). The mean Hb levels after chemotherapy were 117.06 ± 16.67 g/L, which were significantly lower than those before chemotherapy(132.73 ± 16.42 g/L)(P < 0.05). No significant difference was noted between the mean albumin levels before and after chemotherapy(38.29 ± 4.22 g/L vs 38.17 ± 4.54 g/L; P = 0.798). Conclusion Weight loss history, gastrointestinal symptoms, and Hb level decreases are determinant factors of nutritional status in patients with advanced NSCLC and must be included in the screening, evaluation, and treatment of lung carcinoma.

针对电瓶车骑手头盔佩戴情况的无人机巡检方法研究

随着新交通法的实施,电瓶车骑手的头盔佩戴问题引起社会关注,尽管通过使用摄像机可以对骑手进行间接观测,从而减少了直接观察所带来的人力成本,但骑手位置的不确定性,不安全行为的随机性,都给通过固定式摄像机的骑手头盔佩戴检测的准确性和通用性带来了极大挑战。为此,本文设计了一种基于无人机巡检和深度学习的电瓶车骑手佩戴检测方法,该方法首先基于YOLO模型针对无人机采集图片进行分析处理,获取骑手头盔佩戴特征,通过特征分析建立未佩戴头盔骑手的分类模型;然后,针对实际采集过程中的噪声影响,对算法的性能进行验证,并通过噪声抑制方法进一步提升了识别的准确性。所提出的方法可以为电瓶车骑手的安全行驶检测提供新的技术手段,有利于进一步提升交管部门的管理效率。

Outcomes of palliative local treatment in metastatic colorectal cancer patients receiving chemotherapy plus bevacizumab

Objective The aim of this study was to assess the value of palliative local treatment of incurable metastatic lesions in colorectal cancer(CRC) patients receiving chemotherapy plus bevacizumab.Methods Data of 105 patients with histologically confirmed synchronous or metachronous metastatic CRC who received bevacizumab treatment from January 1, 2011 to January 31, 2017 were retrospectively reviewed. Sixteen(15%) patients who were treated with bevacizumab for less than 4 cycles were excluded, and finally, 89(85%) patients were enrolled. Among them, 33(37%) patients who received palliative local treatment were categorized into the palliative local treatment group, and the remaining 56(63%) patients were categorized into the chemotherapy plus bevacizumab group. The primary endpoint was overall survival(OS), which was calculated using Kaplan-Meier survival analyses. Factors possibly influencing survival were evaluated by univariate and multivariate analyses. Adverse events(AEs) were graded according to Common Terminology Criteria for Adverse Events, version 4.0. Grades 1–2 and 3–4 AEs of the two groups were compared and analyzed using the Fisher's exact test and χ~2 analysis.Results The median follow-up period was 20.4 months, ranging from 1 to 60 months. The median OS in the palliative local treatment group was 36.3 months(95% CI, 33.5–39.2), and that in the chemotherapy plus bevacizumab group was 20.5 months(95% CI, 17.6–23.4). Both the univariate(HR 0.13, 95% CI, 0.05–0.30, P < 0.001) and multivariate(HR 0.16, 95% CI, 0.07–0.39, P < 0.001) analyses showed that the addition of palliative local treatment could prolong survival compared with chemotherapy plus bevacizumab alone. There were no significant differences in the rates of common chemotherapy-or bevacizumab-related AEs between the two groups.Conclusion These findings suggest palliative local treatment is an effective and safe method for treating patients with incurable metastatic CRC receiving chemotherapy plus bevacizumab.

Analyses of the clinical characteristics of 49 cases of malignancy with multiple bone lesions as the first manifestation

Objective To investigate the clinical features of several cases of malignancy with multiple bone lesions as the first manifestation.Methods Forty-nine cases of malignancy with multiple bone lesions as the first manifestation were retrospectively analyzed from May 2018 to July 2019.All patients complained of“pain at the site of bone lesion”upon admission.Baseline patient information,such as age,gender,location of bone lesions,etiology,diagnosis method,time of onset was collected.Results The median age of the patients was 56 years old,of which 83.7%(41/49)were aged≥50 years.The median time of onset was 2 months.Among the cases,40 were confirmed as solid tumor bone metastasis,whereas the remaining 9 cases as hematological system tumor.Lung cancer and multiple myeloma were the main tumor types,accounting for 40.8%(20/49)and 16.3%(8/49),respectively.Other common causes were seven cases of cancer affecting the digestive system(three cases of liver cancer,three cases of gastric cancer,and one case of esophageal cancer),as well as seven cases of unknown primary cancer.Half of the solid tumors had only multiple bone metastases but no other distant metastasis.Conclusion Multiple bone lesions accompanied by pain may be the first clinical manifestation in various malignant tumors.The common tumor types were lung cancer,multiple myeloma,and digestive system tumor.It is more common in people aged 50 years and older.Multiple bone lesions might be the only metastasis site of some solid tumors,and its mechanism needs further investigation.

Low-temperature selective synthesis of metastableα-MoC with electrochemical properties:Electrochemical co-reduction of CO_(2)and MoO_(3)in molten salts

Metastable molybdenum carbide(α-MoC),as a catalyst and an excellent support for metal catalysts,has been widely used in thermo/electro-catalytic reactions.However,the selective synthesis ofα-MoC remains a great challenge.Herein,a simple one-pot synthetic strategy for the selective preparation of metastableα-MoC is proposed by electrochemical co-reduction of CO_(2)and MoO_(3)in a low-temperature eutectic molten carbonate.The synthesizedα-MoC shows a reed flower-like morphology.By controlling the electrolysis time and monitoring the phase and morphology of the obtained products,the growth process ofα-MoC is revealed,where the carbon matrix is deposited first followed by the growth ofα-MoC from the carbon matrix.Moreover,by analyzing the composition of the electrolytic products,the formation mechanism forα-MoC is proposed.In addition,through this one-pot synthetic strategy,S-dopedα-MoC is successfully synthesized.Density functional theory(DFT)calculations reveal that S doping enhanced the HER performance ofα-MoC by facilitating water absorption and dissociation and weakening the bond energy of Mo-H to accelerate H desorption.The present work not only highlights the valuable utilization of CO_(2) but also offers a new perspective on the design and controllable synthesis of metal carbides and their derivatives.

Pregnancy Complicated With a Giant Pancreatic Tumor and Decompensation of Liver Cirrhosis:A Case Report and Literature Review

Pregnancy with solid pseudopapillary tumor of the pancreas(SPTP)is rare.Because pregnancy hormones may cause tumor progression,the management and treatment of SPTP need to balance the safety of pregnant women and fetuses with surgical treatment.We reported a case of a giant pancreatic tumor diagnosed during pregnancy that was considered to be SPTP.Examinations also showed hepatitis B virus infection and severe decompensation of liver cirrhosis.Medical termination of pregnancy was performed.The patient has lived with the tumor until now without surgery.We retrieved the published case reports,summarized the clinical characteristics of pregnancy with SPTP,and explored its management during the perinatal period.Most patients with SPTP have a good prognosis with good maternal and fetal outcomes,and it is important to choose an appropriate treatment method and timing.However,pregnancy combined with decompensated liver cirrhosis needs to be terminated in a timely manner because of its high-risk status.

Mechanical properties,thermophysical properties and electronic structure of Yb^(3+)or Ce^(4+)-doped La_(2)Zr_(2)O_(7)-based TBCs

First-principles calculations based on density functional theory were perfo rmed to investigate the cohesive energies,elastic modulus,Debye temperatures,thermal conductivities and density of states of La_(2-x)Yb_(x)Zr_(2)O_(7),La_(2)Zr_(2-x)Ce_(x)O_(7)and La_(2-x)Yb_(x)Zr_(2-x)Ce_(x)O_(7)(x=0.00,0.25,0.50,0.75,1.00)ceramics.The results show that doping Yb~(3+)or Ce~(4+)into La_(2)Zr_(2)O_(7)reduces its elastic modulus,thermal conductivity and Debye temperature.Compared with La_(2-x)Yb_(x)Zr_(2)O_(7)(x≠0.00),La_(2)Zr_(2-x)Ce_(x)O_(7)compounds have better ductility and lower Debye te mperature.The Debye temperature values of La_(2)Zr_(2-x)Ce_(x)O_(7)(x≠0.00)co mpounds are in the range of 485.0-511.5 K.Among all components,the fluorite-type La_(2-x)Yb_(x)Zr_(2-x)Ce_(x)O_(7)(x=0.75,1.00)compounds exhibit better mechanical and thermophysical properties,and their thermal conductivity values are only 1.213-1.246 W/(m·K)(1073 K),which are 14.5%-16.7%lower than that of the pure La_(2)Zr_(2)O_(7).Thus,our findings open an entirely new avenue for TBCs.

Transformation of postsynthesized F-MOF to Fe/N/F-tridoped carbon nanotubes as oxygen reduction catalysts for high power density Zn-air batteries

The oxygen reduction reaction(ORR),an important process in Zn-air batteries(ZABs),shows sluggish reaction kinetics,which significantly impairs the further improvement of battery performance.Thus,rationally designing cathodic catalysts for ZABs has drawn sufficient attention.We herein synthesize and characterize Fe/N/F-tridoped CNTs(FeNFCs)by annealing the postsynthesized trifluoroacetic anhydridemodified Fe-MIL-88B-NH_(2)nanocrystals with melamine at high temperature in a N_(2)atmosphere.Benefiting from the Fe/N/F element doping,high specific surface area,and CNT structure,the FeNFC800 catalyst prepared at 800℃exhibits a preferable half-wave potential of 0.829 V vs.RHE.The Zn-air battery equipped with Fe NFC800 shows a high open-circuit voltage of 1.47 V,a gratifying peak power density of196 mW/cm^(2),and extraordinary long-term stability,outperforming the benchmark 20%Pt/C.

Evaluating RISC-V Vector Instruction Set Architecture Extension with Computer Vision Workloads

Computer vision(CV)algorithms have been extensively used for a myriad of applications nowadays.As the multimedia data are generally well-formatted and regular,it is beneficial to leverage the massive parallel processing power of the underlying platform to improve the performances of CV algorithms.Single Instruction Multiple Data(SIMD)instructions,capable of conducting the same operation on multiple data items in a single instruction,are extensively employed to improve the efficiency of CV algorithms.In this paper,we evaluate the power and effectiveness of RISC-V vector extension(RV-V)on typical CV algorithms,such as Gray Scale,Mean Filter,and Edge Detection.By our examinations,we show that compared with the baseline OpenCV implementation using scalar instructions,the equivalent implementations using the RV-V(version 0.8)can reduce the instruction count of the same CV algorithm up to 24x,when processing the same input images.Whereas,the actual performances improvement measured by the cycle counts is highly related with the specific implementation of the underlying RV-V co-processor.In our evaluation,by using the vector co-processor(with eight execution lanes)of Xuantie C906,vector-version CV algorithms averagely exhibit up to 2.98x performances speedups compared with their scalar counterparts.

Climatic significance of n-alkanes and their compound-specific dD values from lake surface sediments on the Southwestern Tibetan Plateau

The content and hydrogen isotope ratios of n-alkanes extracted from recent lake surface sediments sampled from nine lakes in three different climate zones on the Southwestern Tibetan Plateau were analyzed.Values were compared with n-alkanes in plants from lake drainages,and dD values of meteoric water,lake water,and mean annual precipitation.The results showed that n-C23was predominantly derived from aquatic plants,and n-C27–n-C33from terrestrial higher plants.The average carbon chain length of n-C27–n-C33(ACL27–33)was positively correlated with the mean annual precipitation.dD values of the long-chain n-alkanes n-C29and n-C31of terrestrial origin(varying between-214%and-169%,and-226%and-185%,respectively)were inversely correlated with mean annual precipitation;but in accordance with the average annual variations in dD(OIPC),dD values of n-C31were strongly related to the dD values of growing season meteoric water(R2=0.74).The large difference between dD values of n-C23of aquatic origin and n-C31(an average of about 27%)demonstrates the enrichment of the lake water dD compared to precipitation,caused by strong evaporation in the semiarid–arid areas of the southwestern Tibetan Plateau.Average value of en C25 31=p(-95%)is evidently higher than the value observed in European wet regions(-128%);besides,en C31(about-116%)is constant along the study transect(SD=9),which indicates that n-C31is a useful proxy for the environment.