Geo-engineered buffer capacity of two-layered absorbing system under the impact of rock avalanches based on Discrete Element Method

Many rock avalanches were triggered by the Wenchuan earthquake on May 12, 2008 in southwest China. Protection galleries covered with a single soil layer are usually used to protect against rockfall. Since one-layer protection galleries do not have sufficient buffer capacity, a two-layered absorbing system has been designed. This study aims to find whether an expanded poly-styrol （EPS） cushion, which is used in the soil-covered protection galleries for shock absorption, could be positioned under dynamic loadings. The dynamic impacts of the two-layered absorbing system under the conditions of rock avalanches are numerically simulated through a 2D discrete dement method. By selecting reasonable parameters, a series of numerical experiments were conducted to find the best combination for the two- layered absorbing system. The values of the EPS layer area as a percentage of the total area were set as 0% （Sl）, 22~ （S2）, and 70% （$3）. 22~ of the area of the EPS layer was found to be a reasonable value, and experiments were conducted to find the best position of the EPS layer in the two-layered absorbing system. The numerical results yield useful conclusions regarding the interaction between the impacting avalanches and the two-layered absorbing system. The soil layer can absorb the shock energy effectively and S2 （0.4-m thick EPS cushion covered with soil layer） is the most efficient combination, which can reduce the impact force, compared with the other combinations.

Characteristic analysis of scattering field in two-layer media by Green's function

The problem of three-dimensional(3D) acoustic scattering in a complex medium has aroused considerable interest of researchers for many years. An ultrasonic scattered field calculating technique is proposed to study the scattering echo from strongly scattered materials in a two-layer medium in this work. Firstly, with the high frequency stationary phase method,the Green's function of two-layer fluid media is derived. And then based on the idea of integral equation discretization,the Green's function method is extended to two-layer fluid media to derive the scattering field expression of defects in a complex medium. With this method, the scattering field of 3D defect in a two-layer medium is calculated and the characteristics of received echoes are studied. The results show that this method is able to solve the scattering P wave field of 3D defect with arbitrary shape at any scattering intensity in two-layer media. Considering the circumstance of waterimmersion ultrasonic non-destructive test(NDT), the scattering sound field characteristics of different types of defects are analyzed by simulation, which will help to optimize the detection scheme and corresponding imaging method in practice so as to improve the detection quality.

Two-layer cold storage method for pancreas and islet cell transplantation

The two-layer cold storage method (TLM) was f irst reported in 1988, consisting of a perfluorochemical (PFC) and initially Euro-Collins' solution, which was later replaced by University of Wisconsin solution (UW). PFC is a biologically inert liquid and acts as an oxygen-supplying agent. A pancreas preserved using the TLM is oxygenated through the PFC and substrates are supplied by the UW solution. This allows the pancreas preserved using the TLM to generate adenosine triphosphate during storage, prolonging the preservation time. In a canine model, the TLM was shown to repair and resuscitate warm ischemically damaged pancreata during preservation, improve pancreas graft survival after transplantation, and also improve the islet yield after isolation. Clinical trials using the TLM in pancreas preservation before whole-pancreas transplantation and islet isolation have shown promising outcomes. We describe the role of the TLM in pancreas and islet transplantation.

An easier method for performing a pancreaticojejunostomy for the soft pancreas using a fast-absorbable suture

AIM: To clarify the usefulness of a new method for performing a pancreaticojejunostomy by using a fast-absorbable suture material irradiated polyglactin 910, and a temporary stent tube for a narrow pancreatic duct with a soft pancreatic texture.METHODS: Among 63 consecutive patients with soft pancreas undergoing a pancreaticoduodenectomy from 2003 to 2006, 35 patients were treated with a new reconstructive method. Briefly, after the pancreatic transaction, a stent tube was inserted into the lumen of the pancreatic duct and ligated with it by a fast-absorbable suture. Another tip of the stent tube was introduced into the intestinal lumen at the jejunal limb, where a purse-string suture was made by another fast-absorbable suture to roughly fix the tube. The pancreaticojejunostomy was completed by ligating two fast-absorbable sutures to approximate the ductal end and the jejunal mucosa, and by adding a rough anastomosis between the pancreatic parenchyma and the seromuscular layer of the jejunum. The initial surgical results with this method were retrospectively compared with those of the 28 patients treated with conventional duct-to-mucosa anastomosis.RESULTS: The incidences of postoperative morbidity including pancreatic fistula were comparable between the two groups (new; 3%-17% vs conventional; 7%-14% according to the definitions). There was no mortality and re-admission. Late complications were also rarely seen.CONCLUSION: A pancreaticojejunostomy using an irradiated polyglactin 910 suture material and a temporary stent is easy to perform and is feasible even in cases with a narrow pancreatic duct and a normal soft pancreas.

Green Functions with Pulsating Sources in A Two-Layer Fluid of Finite Depth

The derivation of Green function in a two-layer fluid model has been treated in different ways. In a two-layer fluid with the upper layer having a free surface, there exist two modes of waves propagating due to the free surface and the interface. This paper is concerned with the derivation of Green functions in the three dimensional case of a stationary source oscillating. The source point is located either in the upper or lower part of a two-layer fluid of finite depth. The derivation is carried out by the method of singularities. This method has an advantage in that it involves representing the potential as a sum of singularities or multipoles placed within any structures being present. Furthermore, experience shows that the systems of equations resulted from using a singularity method possess excellent convergence characteristics and only a few equations are needed to obtain accurate numerical results. Validation is done by showing that the derived two-layer Green function can be reduced to that of a single layer of finite depth or that the upper Green function coincides with that of the lower, for each case. The effect of the density on the internal waves is demonstrated. Also, it is shown how the surface and internal wave amplitudes are compared for both the wave modes. The fluid in this case is considered to be inviscid and incompressible and the flow is irrotational.

Electromagnetic scattering from two-layered rough interfaces with a PEC object:vertical polarization

Electromagnetic （EM） scattering from a stack of two rough interfaces separating a homogeneous medium with a perfectly electric conducting （PEC） object has been calculated through the method of moments for vertical polarization. Theoretical formulations of EM scattering from multi-layered rough interfaces with a PEC object have been derived in detail and the total fields and their normal derivatives on the rough interfaces are solved. The two-layered model is a special case. In this work, a Gaussian rough surface was applied to simulate the rough interface. A cylinder was located above, between or below the two-layered rough interfaces. Through numerical simulations, the validity of this work is demonstrated by comparing it with existing scattering models, which are special cases that include a PEC object located above/below a single-layered rough interface and two-layered rough interfaces without an object. Subsequently, the influences of characteristic parameters, such as the relative permittivity of the medium, as well as the average height between the two rough surfaces, on the bistatic scattering coefficient are discussed.

A Similarity Technique for Solving Two-Layer Shallow-Water Equations

This paper is devoted to the analysis of the two-layer shallow-water equations representing gravity currents. A similarity technique which is the characteristic function method is applied for this study. The application of the characteristic function method makes it possible to obtain the similarity forms depending on a group of infinitesimal transformations. Thus, the number of independent variables is reduced by one and the governing partial differential equations with the auxiliary conditions reduce to a system of ordinary differential equations with the appropriate auxiliary conditions. Numeric solutions are presented and discussed.

“十字”缝合法在腹腔镜APR会阴部切口重建中的应用

目的:探讨“十字”缝合法在腹腔镜腹会阴联合切除术(abdominoperineal resection,APR)会阴部切口重建中的应用。方法:选取2017年1月—2022年12月钦州市第一人民医院胃肠外科收治的60例低位直肠癌患者。随机将其分为试验组和对照组,各30例。两组均给予腹腔镜APR,试验组腹腔镜APR会阴部切口重建应用“十字”缝合法,对照组腹腔镜APR会阴部切口重建应用常规间断缝合法。比较两组围手术期指标,术后7 d切口愈合情况,并发症。结果:试验组手术时间、住院时间均短于对照组,术中出血量及引流量均少于对照组,正常饮食时间、腹腔引流管拔管时间均早于对照组,差异有统计学意义(P<0.05)。试验组切口愈合情况优于对照组,差异有统计学意义(P<0.05)。试验组并发症发生率低于对照组,差异有统计学意义(P<0.05)。结论:“十字”缝合法用于腹腔镜APR会阴部切口重建,能够降低切口张力,促进伤口愈合,住院时间短。

2D multi-scale hybrid optimization method for geophysical inversion and its application

Local and global optimization methods are widely used in geophysical inversion but each has its own advantages and disadvantages. The combination of the two methods will make it possible to overcome their weaknesses. Based on the simulated annealing genetic algorithm （SAGA） and the simplex algorithm, an efficient and robust 2-D nonlinear method for seismic travel-time inversion is presented in this paper. First we do a global search over a large range by SAGA and then do a rapid local search using the simplex method. A multi-scale tomography method is adopted in order to reduce non-uniqueness. The velocity field is divided into different spatial scales and velocities at the grid nodes are taken as unknown parameters. The model is parameterized by a bi-cubic spline function. The finite-difference method is used to solve the forward problem while the hybrid method combining multi-scale SAGA and simplex algorithms is applied to the inverse problem. The algorithm has been applied to a numerical test and a travel-time perturbation test using an anomalous low-velocity body. For a practical example, it is used in the study of upper crustal velocity structure of the A＇nyemaqen suture zone at the north-east edge of the Qinghai-Tibet Plateau. The model test and practical application both prove that the method is effective and robust.

颌面部创伤清创缝合术后患儿照护者居家照护知识需求量表的构建及应用

目的:构建及验证颌面部创伤清创缝合术后患儿照护者居家照护知识需求量表。方法:通过文献回顾、医护临床经验总结、病人开放式调查表调查,编制颌面部创伤清创缝合术后病人照护者居家护理知识需求调查表。采用便利抽样法于2022年12月—2023年4月抽取四川省某三级口腔专科医院急诊科就诊的行清创缝合术的115名颌面部创伤患儿的主要照护者进行横断面调查。结果:最终形成包括4个维度(伤口常规护理知识、伤口并发症防治、用药及二期治疗、瘢痕及其他管理)、20个条目的颌面部创伤清创缝合术后患儿照护者居家照护知识需求量表。量表及各维度Cronbach'sα系数为0.860~0.960,折半信度为0.743~0.948。横断面调查结果显示,主要照护者的各维度知识需求得分均较高,伤口常规护理知识需求最高。结论:构建的颌面部创伤清创缝合术后患儿照护者居家照护知识需求量表具有良好的科学性和可靠性,可为评估颌面部创伤清创缝合术后患儿照护者的居家照护知识需求提供参考。

缝线牵引悬吊法在胸乳入路腔镜甲状腺癌根治术中的应用

目的探讨缝线牵引悬吊法在胸乳入路腔镜甲状腺手术中的应用价值。方法回顾性分析2020年1月~2022年12月108例甲状腺乳头状癌行胸乳入路腔镜单侧腺叶切除、同侧中央区淋巴结清扫的资料。2021年5月后逐步开展用2-0聚丙烯缝线牵引悬吊带状肌、气管及甲状腺腺叶的缝线牵引悬吊法。缝线牵引悬吊组51例,常规腔镜组57例。比较2组术中及术后指标。结果2组均顺利完成手术。缝线牵引悬吊组较常规腔镜组的腺叶切除手术时间短[(35.3±7.3)min vs.(43.4±8.4)min,t=-5.342,P<0.001],中央区淋巴结清扫手术时间短[(20.1±3.5)min vs.(27.7±4.9)min,t=-9.271,P<0.001],术中出血量少[10(5~15)ml vs.15(5~30)ml,Z=-6.250,P<0.001],清扫中央区淋巴结数量多[8(3~13)个vs.6(4~10)个,Z=3.272,P=0.001],术后一过性喉返神经损伤少,但差异无统计学意义(1例vs.8例,χ^(2)=3.678,P=0.055]。2组术后住院时间、淋巴漏、标本发现甲状旁腺、甲状旁腺功能减退、疼痛评分及美容效果评分差异无统计学意义(P>0.05)。结论缝线牵引悬吊法可缩短手术时间,减少术中出血,减少喉返神经损伤的发生,增加中央区淋巴结清扫数目。

胸腔镜膈肌折叠术治疗小儿膈膨升2种不同缝线缝合打结法的比较

目的探讨改良Prolene线双头针“U”型缝合联合腔外腔内结合打结法在胸腔镜膈肌折叠术治疗小儿膈膨升中应用的可行性、安全性及手术效果。方法回顾性分析我院2010年5月~2022年5月70例膈膨升行胸腔镜膈肌折叠术的临床资料,根据缝合打结方法的不同分为改良组(改良Prolene线双头针“U”型缝合联合腔外腔内结合打结法,n=30)和常规组(腔内缝合打结法,n=40),比较2组患儿围术期指标及有无线结松开或膈膨升复发等。结果70例手术均顺利完成,无中转开放手术。改良组手术时间明显短于常规组[(35.3±7.4)min vs.(64.7±10.8)min,t=13.521,P=0.000]。2组术中出血量、留置胸腔引流管时间、术后住院时间、术前术中和术后动脉血气pH值、PO_(2)、PCO_(2)和术后术侧膈肌轻微上升等差异无统计学意义(P>0.05)。70例术后随访6~24个月,中位随访时间12个月,均无线结松开和膈膨升复发,无死亡。结论胸腔镜膈肌折叠术治疗小儿膈膨升采用改良Prolene线双头针“U”型缝合联合腔外腔内结合打结法安全可行、疗效确切,且简单易操作,具有一定腔镜手术基础的医生可快速掌握,适宜有条件的医院推广开展。

贯穿连续缝合法用于鼻中隔偏曲矫正手术的价值分析

目的 观察在鼻中隔偏曲矫正手术实施贯穿连续缝合法的效果。方法 选取中国人民解放军联勤保障部队第九八一医院于2021年2月—2023年8月收治的60例接受鼻中隔偏曲矫正手术治疗的患者作为研究对象,用随机数表法分为研究组和对照组,各30例。研究组采用贯穿连续缝合法,对照组采用鼻腔填塞法。比较两组患者的病情程度、主观症状、并发症发生率。结果 治疗后,研究组的病情程度评分、主观症状评分、并发症发生率低于对照组,差异有统计学意义(P均<0.05)。结论 在鼻中隔偏曲矫正手术中采取贯穿连续缝合法,可以改善病情程度,缓解主观症状,降低并发症发生风险。

Opinion consensus incorporating higher-order interactions in individual-collective networks

In the current information society, the dissemination mechanisms and evolution laws of individual or collective opinions and their behaviors are the research hot topics in the field of opinion dynamics. First, in this paper, a two-layer network consisting of an individual-opinion layer and a collective-opinion layer is constructed, and a dissemination model of opinions incorporating higher-order interactions(i.e. OIHOI dissemination model) is proposed. Furthermore, the dynamic equations of opinion dissemination for both individuals and groups are presented. Using Lyapunov's first method,two equilibrium points, including the negative consensus point and positive consensus point, and the dynamic equations obtained for opinion dissemination, are analyzed theoretically. In addition, for individual opinions and collective opinions,some conditions for reaching negative consensus and positive consensus as well as the theoretical expression for the dissemination threshold are put forward. Numerical simulations are carried to verify the feasibility and effectiveness of the proposed theoretical results, as well as the influence of the intra-structure, inter-connections, and higher-order interactions on the dissemination and evolution of individual opinions. The main results are as follows.(i) When the intra-structure of the collective-opinion layer meets certain characteristics, then a negative or positive consensus is easier to reach for individuals.(ii) Both negative consensus and positive consensus perform best in mixed type of inter-connections in the two-layer network.(iii) Higher-order interactions can quickly eliminate differences in individual opinions, thereby enabling individuals to reach consensus faster.

两种4股交叉屈肌腱缝合方法的生物力学比较

目的探究运用Mclarney与Adelaide缝合法在猪趾屈肌腱生物力学中的性能。方法取新鲜冷冻猪前蹄趾深屈肌腱40条,按随机数表法分为两组。A组采用Adelaide法缝合肌腱,B组采用McLarney法缝合肌腱。在生物力学机上拉伸肌腱,记录肌腱2 mm间隙时的负荷与肌腱断裂时最大拉伸负荷,检查记录肌腱失效模式。结果两组2 mm间隙负荷分别为(50.06±4.47)N、(31.26±2.67)N,最大负荷分别为(69.09±5.11)N、(48.58±4.41)N;两组2 mm间隙负荷、最大负荷之间差异有统计学意义(P=0.001,P<0.05);A组有17例缝线断裂、3例肌腱撕脱;B组有4例缝线断裂、16例肌腱撕脱。结论Adelaide缝合法比Mclarney缝合法有更好的力学性能,可以提供更大的抗张强度,能够为患者术后早期主动功能锻炼提供安全保障。

预置缝线的间断缝合法改进腹腔镜下T管缝合的效果

目的比较腹腔镜下T管缝合时预置缝线法与传统缝合方法的效果差异。方法回顾性分析2020年6月至2023年9月间空军特色医学中心行腹腔镜T管缝合的患者的临床资料,对照组采用传统的T管缝合方法,研究组采用预置缝线的T管缝合方法:间断缝合,进针和出针时前一针的缝线不打紧,每组24例。比较两组患者T管缝合时间和注水试验阳性率。结果研究组术中T管缝合时间少于对照组[(12.61±0.88)min vs(17.62±0.58)min,t=-23.34,P<0.001],注水试验阳性率低于对照组[0 vs 25%(6/24),P=0.029],差异均有统计学意义。结论应用预置缝线的间断缝合法可提高腹腔镜下T管缝合速度,使缝合更确切,较传统方法有明显优势。

外内缝合法与全内缝合法在老年半月板损伤关节镜治疗中的应用

目的:探究外内缝合法与全内缝合法在老年半月板损伤关节镜治疗中的应用效果。方法:采用目的抽样法选择2021年1月—2022年6月在徐州矿务集团总医院治疗的100例半月板损伤的老年患者,随机将其分为对照组和试验组,对照组(50例)采用外内缝合法,试验组(50例)采用全内缝合法进行关节镜治疗,并对治疗效果进行6个月的随访。对两组围手术期指标、膝关节功能、生活质量和术后并发症进行比较。结果:试验组手术时间短于对照组,差异有统计学意义(P<0.05);两组术中出血量和术后下床时间比较,差异均无统计学意义(P>0.05)。术后6个月,两组膝关节损伤和骨关节炎评分(KOOS)和国际膝关节文献编制委员会膝关节评估表(IKDC)评分及健康调查简表(SF-36)各维度评分均提高,且试验组均高于对照组(P<0.05)。试验组并发症发生率为6.00%,低于对照组的22.00%,差异有统计学意义(P<0.05)。结论:两种缝合方法在中长期随访中均取得良好的疗效,但全内缝合法在手术用时方面和降低并发症发生率方面具有优势。

视频分散法提高颜面部创伤患儿美容缝合配合度的效果研究

目的:探讨视频分散法在提高颜面部创伤患儿美容缝合配合度中的应用效果。方法:选择2021年1月-2022年1月笔者医院收治的79例颜面部损伤患儿,按随机数字表法分为对照组38例和观察组41例。对照组采用常规美容缝合护理,观察组在对照组的基础上开展视频分散法干预,比较两组患儿美容缝合配合度、美容缝合效果和家属对缝合的满意度。结果:干预后,观察组患儿的美容缝合配合度、美容缝合效果和家属对缝合的满意度均明显提高,患儿伤口评估时间和缝合耗时均较对照组降低,差异均有统计学意义(P<0.05)。结论:视频分散法能够提高患儿美容缝合时的配合度和患儿家属对缝合的满意度,有利于创面治疗和愈合,值得在临床推广应用。

关节镜下改良Mason-Allen与缝线桥技术治疗中小型肩袖撕裂的早期疗效比较

目的比较关节镜下改良Mason-Allen(mMA)与缝线桥技术治疗中小型肩袖撕裂的早期疗效。方法选取中小型肩袖撕裂患者60例,分为mMA组和缝线桥组,各30例。mMA组采用mMA技术治疗,缝线桥组采用缝线桥技术治疗。比较两组患者手术时间、锚钉数量、术中出血量、肩关节活动度、疼痛视觉模拟评分法(VAS)、美国肩肘外科医师学会(ASES)评分、Constant-Murley评分和再撕裂率。结果mMA组手术时间短于缝线桥组,术中锚钉使用数量少于缝线桥组,差异均有统计学意义(P<0.05);两组患者术中出血量比较,差异无统计学意义(P>0.05)。术后,两组患者肩关节活动度较术前增大,差异有统计学意义(P<0.05),两组患者组间肩关节活动度比较,差异无统计学意义(P>0.05)。术后,两组患者VAS较术前降低,ASES评分和Constant-Murley评分较术前增高,差异均有统计学意义(P<0.05);两组患者组间VAS、ASES评分和Constant-Murley评分比较,差异均无统计学意义(P>0.05)。两组患者再撕裂率比较,差异无统计学意义(P>0.05)。结论关节镜下mMA与缝线桥技术治疗中小型肩袖撕裂的早期疗效相当,但mMA的手术时间更短,锚钉使用量更少。

两种路径折叠对接缝合法治疗剖宫产瘢痕憩室的疗效

目的对比腹腔镜和阴式子宫瘢痕折叠对接缝合法治疗剖宫产瘢痕憩室的临床疗效。方法选取2021年1月至2022年12月本院收治的剖宫产瘢痕憩室患者60例,随机分为腹腔镜组和阴式组,各30例。腹腔镜组行宫腔镜检查联合腹腔镜下子宫瘢痕折叠对接缝合术,阴式组行宫腔镜检查联合经阴道子宫瘢痕折叠对接缝合术,对比两组围手术期指标、术后3个月憩室修复情况及月经恢复情况,并行统计分析。结果两组术中出血量、住院时间差异无统计学意义(P>0.05),腹腔镜组手术时间长于阴式组(P=0.020),住院费用高于阴式组(P<0.001);腹腔镜组与阴式组比较,术后3个月经期延长改善的治愈率及有效率差异均无统计学意义(P>0.05),术后3个月憩室修复的治愈率及有效率差异均无统计学意义(P>0.05)。结论腹腔镜及经阴道两种路径下折叠对接缝合法对剖宫产瘢痕憩室的治疗效果相当。经阴道途径手术费用更低,体表无创口,真正体现微创理念,值得临床推广。