完全腹腔镜胰十二指肠切除术6例临床疗效分析

目的 评估完全腹腔镜胰十二指肠切除术（laparoscopic pancreaticoduodenectomy,LPD）的可行性、安全性。方 法 采用LPD 治疗胰头或十二指肠肿瘤患者6 例,回顾性分析手术时间、术中出血量、淋巴结清扫数目、术后肛门排气时间、术后住院天数、手术并发症发生率及术后短期疗效。结果 6 例手术均在完全腹腔镜下完成,无中转开腹病例。手术时间（380.5±38.1）min;出血量（241.7±189.3）ml;清扫淋巴结（15.3±2.8）枚;平均肛门排气时间（3.5±1.0）d;术后住院（14.0±5.7）d。手术并发症发生率为33.3％（2/6）,其中轻度胰漏1例,肺炎1例;本组患者术后随访3~12个月,无肿瘤复发及转移。结论 LPD 安全、可行,能达到胰头或十二指肠肿瘤根治性切除的目的。     

钼靶金属丝联合超声定位在不可触及乳腺钙化病灶手术中的应用价值

目的 探讨钼靶金属丝和超声定位在不可触及乳腺钙化病灶（NPBC）手术中的应用价值。方法 将2012 年8 月至 2014 年5 月收治的135 例NPBC患者随机分为钼靶金属丝定位组（MWG 组）和钼靶金属丝联合术中超声定位组（CWUG 组）,MWG组60例患者行钼靶金属丝定位切除,CWUG组75例患者行钼靶金属丝和术中超声联合定位切除,比较两组患者手术成功切除率、手术时间、再次手术率、切除标本重量、术后乳房外形满意率。结果 两种方法均成功切除了NPBC,MWG组有6例患者再次手术切除,再次手术率为10.0%（6/60）,CWUG组没有再次手术切除患者,再次手术率0.0%（0/75）;两组患者平均手术时间分别为（25.20±3.70）min 和（23.30±4.50）min,组间比较均无统计学差异（均P＞0.05）。两组手术切除标本平均重量分别为（27.68±6.97）g 和（21.65±7.89）g;MWG 组术后乳房外形满意率为55.0%（33/60）,CWUG组满意率为92.0%（69/75）,组间比较均有统计学差异（均P＜0.05）。结论 联合应用钼靶金属丝和术中超声定位切除NPBC 有较多优点,如病灶遗漏少,对乳房外形影响小等,值得临床推广。     

腹腔镜下经肠系膜途径与结肠旁 途径左侧输尿管上段切开取石术 的疗效比较

目的 寻找疗效更佳的腹腔镜下左侧输尿管上段切开取石术的手术途径。方法 收集43例经肠系膜途径（A组）和 46 例结肠旁途径（B 组）患者的手术时间、术中出血量、术后肠道功能恢复时间、住院时间、术后并发症、下床活动时间等临床资料,比较两组的差异。结果 A 组在手术时间、术中出血量、术后肠道功能恢复时间、住院天数明显优于B 组,差异有统计学意义（均P＜0.05）;术后并发症、下床活动时间,两组差异无统计学意义（均P＞0.05）。结论 腹腔镜下经肠系膜途径左侧输尿管上段切开取石术是一种更安全、有效、微创的手术方法,值得在临床上推广应用。     

实时超声检测在脑海绵状血管瘤切除术中的应用研究

目的探讨术中实时超声检测在脑海绵状血管瘤手术中的应用价值.方法将39例脑海绵状血管瘤患者按术中是否采用实时超声检测引导手术分为两组.超声引导组20例,术中通过超声检测显示海绵状血管瘤的位置、大小、形态、深度及其与周围组织和血管的关系,制定最佳手术入路,并通过实时扫描,监测病灶的切除情况,病灶切除后再次超声探查有无残留病灶和血肿.另19例为对照组,术中不用超声引导,其他均按传统方法手术.比较两组患者病灶切除时间、脑组织切开次数、切口肿瘤直径比值以及患者症状改善及并发症发生情况.结果(1)两组患者均无手术死亡,病灶均在手术显微镜下全切除.影像学与病理检查诊断符合率达100%.(2)两组患者病灶在手术显微镜下均被发现,超声引导组患者术中病灶显示率为100%,并完整显示病灶的大小、位置、范围及形态,准确定位.(3)脑组织切开次数超声引导组均在3次以下,而对照组仅10例(52.63%)在3次以下,7例(36.84%)达3次以上;切口肿瘤直径比值超声引导组为1.22±0.22,低于对照组的1.45±0.36;病灶平均切除时间超声引导组为(55.70±12.66)min,少于对照组的(82.16±31.23)min;并发症发生率超声引导组为5.00%,明显低于对照组的15.79%;两组上述数据的差异均有统计学意义(均P<0.05).结论术中实时超声引导对脑海绵状血管瘤病灶的定位准确、可靠,能指导术者准确选择手术入路,避开重要的脑功能区、血管和其他重要结构,精准切除病灶,缩短手术时间,减少神经组织损伤和降低手术并发症发生率.     

超声内镜辅助下ESD治疗上消化道隆起性病变的疗效及安全性探讨

目的探讨超声内镜对于应用ESD治疗上消化道隆起性病变的疗效及安全性。方法20例上消化道黏膜局限性隆起病变,先行超声内镜检查,再采用ESD进行治疗,比较术前超声内镜诊断与内镜治疗术后病理结果的一致性,记录手术耗时、整块切除率、并发症发生率及局部残留复发率。结果食管病变6例,其中早癌及高级别上皮内瘤变各1例,平滑肌瘤4例;胃内病变14例,其中胃早癌及高级别上皮内瘤变各3例,异位胰腺1例,间质瘤7例。术前EUS诊断与术后病理结果的一致性为100%。手术时间16~100（32.8±15.7）min;整块切除率85%,出血率为20%,穿孔率10%,术后随访1～12个月,无残留与复发。结论超声内镜对消化道黏膜隆起性病变诊断准确率高,超声内镜辅助下ESD治疗上消化道隆起性病变安全有效。     

纤维蛋白胶联合角膜缘干细胞移植在翼状胬肉治疗中的应用

目的 评估纤维蛋白胶（fibrin glue，FG）联合角膜缘干细胞移植在翼状胬肉治疗中的效能及安全性。方法 将50例原发性鼻侧翼状胬肉患者根据胬肉侵犯角膜的面积配对分为两组，每组25 例、25 眼。切除胬肉后，取患眼颞上方球结膜瓣覆盖于巩膜裸露区，实验组25 眼用FG 固定植片，对照组25 眼用10-0 尼龙线固定植片。于术后第1、3、7、14 天及1、2、6 个月对患者进行随访，观察手术耗时、患者术后不适症状、复发率及并发症等指标。结果 FG 组平均手术耗时明显短于缝线组（P＜0.01）且其各项术后不适症状均较缝线组轻（均P＜0.01）。至随访6 个月时FG 组无一例胬肉复发，缝线组复发1 例，两组复发率及并发症发生率的差异均无统计学意义（均P ＞0.05）。结论 在翼状胬肉切除联合角膜缘干细胞移植术中使用FG 可替代手术缝线，该法在缩短手术时间的同时还可减轻患者术后症状，长期随访结果令人满意，值得在临床上推广。     

PTGD 与腹腔镜胆囊切除序贯微创治疗高危急性胆囊炎疗效分析

目的 探讨经皮经肝胆囊穿刺引流术（PTGD）与腹腔镜胆囊切除（LC）序贯微创治疗高危急性胆囊炎（AC）的疗效。方法 对76 例高危AC患者根据就诊时患者全身状况、心肺功能及胆囊B 超检查结果,分别采用PTGD 加延期LC 治疗（36 例,为PTGD 组）及同期直接LC 治疗（40 例,为Non-PTGD 组）,观察并比较两组患者LC 手术时间、术中失血量、中转开腹率、术后并发症发生率及住院时间。结果 PTGD 组手术时间、住院时间均明显短于Non-PTGD 组（t =1.96、1.84,均P＜0.05）;PTGD 组术中失血量明显少于Non-PTGD 组（t =2.03,P＜0.05）;PTGD 组中转开腹率、术后并发症发生率均明显低于Non-PTGD 组（字2 =6.74、6.97,P＜0.05）。结论 PTGD 与LC 序贯微创治疗高危AC 疗效确切、安全,值得临床推广。     

贮存式自体输血在人工髋关节置换术中的安全性研究

目的 观察贮存式自体输血在人工髋关节置换术中的临床效果,探讨在人工髋关节置换术中实施贮存式自体输血 对患者安全的影响。方法 收集采用贮存式自体输血的50 例人工髋关节置换术患者为观察组,采用异体输血的50例患者为对照组,观察两组患者手术前后血常规、血电解质及围术期恢复情况。结果 观察组患者手术前后血常规、血电解质指标未出现明显变化（P＞0.05）,其中发生肺炎1 例,高热1 例,住院时间（6.5±1.7）d。对照组患者手术后血常规指标明显低于手术前,血电解质指标中血钾高于术前,血钙低于术前（P＜0. 05 或0.01）,术后出现高热5 例,肺炎3 例,泌尿道感染3例,住院时间（9.8±3.8）d,两组患者输血后感染率和住院时间比较,差异有统计学意义（P＜0.05）。结论 贮存式自体输血科学安全、经济有效,减少患者异体输血并发症,节约血源,可广泛应用于人工髋关节置换术等择期手术。     

局部晚期直肠癌新辅助调强放化疗后腹腔镜手术I 期研究

目的 评估局部晚期直肠癌新辅助调强放化疗后腹腔镜手术的安全性及有效性。方法 选择24例病理确诊II～III 期的直肠腺癌患者,原发病灶及转移淋巴结外放1cm 予放疗,剂量55Gy,每次2.2Gy,盆腔放疗剂量为45Gy,每次1.8Gy。卡培他滨化疗按每日500、750、1 000、1 250、1 650、1 800 及2 000 mg/m2 共7 个剂量梯度（每个梯度3 例）爬坡进行,于放疗d1-14 及d22-35口服。观察患者的剂量限制性毒性。放化疗后6～8 周内行腹腔镜下直肠癌全系膜切除术。结果 在卡培他滨第1 至第4 剂量梯度未见剂量限制性毒性出现。在第5 剂量梯度组中1 例出现3 级腹泻,新入组3例患者无剂量限制性毒性发生。在第6剂量梯度,2 例患者分别出现3级腹泻和3级放射性皮炎,故第5梯度卡培他滨剂量[1 650mg/（m2·d）]被推荐为进一步研究使用剂量。24 例患者手术均达R0切除,5 例（20.8%）到达病理完全缓解。术后出现会阴部感染及肠梗阻各1 例,术后30d无死亡病例。结论 直肠癌新辅助调强放化疗后腹腔镜手术治疗安全有效,推荐新辅助治疗中卡培他滨剂量为1 650mg/（m2·d）。     

改良经脐单孔三通道腹腔镜精索静脉高位结扎术的临床应用

目的 探讨改良经脐单孔三通道腹腔镜精索静脉高位结扎术的可行性。方法 2011 年3 月至2013 年3 月对25例精索静脉曲张患者采用改良经脐单孔三通道腹腔镜精索静脉高位结扎术（A 组）,30 例精索静脉曲张患者采用传统三孔法腹腔镜下精索内静脉高位结扎术（B 组）,比较并分析两种术式的手术时间、术后住院时间、术后近期并发症、精液常规变化、术后美容效果等。结果 单侧及双侧手术时间A 组分别为（35.0±8.6）min 及（45.0±11.5）min, B组分别为（18.0±6.5）min 及（25.0±8.2）min,A 组长于B 组,差异有统计学意义（P＜0.05）。术后住院时间A 组为（2.1±0.3）d,B 组为（2.5±0.5）d,差异无统计学意义（P ＞0.05）。两组术后近期并发症发生率及精液改善率均无统计学差异（均P ＞0.05）。A 组手术美容效果优于B 组。结论 改良经脐单孔三通道腹腔镜精索静脉高位结扎术不需专用单孔多通道操作平台,手术操作简化,安全有效,术后腹壁不留瘢痕,值得临床推广。     

术前经动脉化疗栓塞治疗婴儿肾母细胞瘤的疗效观察

目的探讨术前经动脉化疗栓塞治疗婴儿肾母细胞瘤的可行性。方法2009年6月至2014年5月收治6例婴儿单侧肾母细胞瘤,术前评估肿瘤手术一期切除困难,所有婴儿均行经导管肾动脉化疗栓塞,术后4周内行肿瘤根治性手术切除,记录并分析6例婴儿的治疗结果、并发症及随访结果。结果6例婴儿介入后肿瘤体积均缩小,平均缩小39.03%（23.95%~61.8%）,介入治疗总有效率达83.33%（5/6）;手术中瘤体完整切除率为100%,无肿瘤破溃及污染腹腔情况。手术后随访时间平均为42.8个月,无肿瘤复发、远处转移及死亡。结论术前经动脉化疗栓塞治疗婴儿巨大肾母细胞瘤是安全、有效的,能为一期手术切除困难的肾母细胞瘤患儿提供一种新的治疗模式。     

Surgical case scheduling as a generalized job shop scheduling problem

Surgical case scheduling allocates hospital resources to individual surgical cases and decides on the time to perform the surgeries. This task plays a decisive role in utilizing hospital resources efficiently while ensuring quality of care for patients. This paper proposes a new surgical case scheduling approach which uses a novel extension of the Job Shop scheduling problem called multi-mode blocking job shop (MMBJS). It formulates the MMBJS as a mixed integer linear programming (MILP) problem and discusses the use of the MMBJS model for scheduling elective and add-on cases. The model is illustrated by a detailed example, and preliminary computational experiments with the CPLEX solver on practical-sized instances are reported.     

SIR epidemics with stochastic infectious periods

We consider an SIR model for the spread of an epidemic in a closed and homogeneously mixing population, where the infectious periods are represented by an arbitrary absorbing Markov process. A version of this process starts whenever an infection occurs, and the contamination rate of the newly infected individual is a function of its state. When his process is absorbed, the individual becomes a removed case. We use a martingale approach to derive the distribution of the final epidemic size and severity for this class of models. Next, we examine some special cases. In particular, we focus on situations where the infection processes are Brownian motions and where they are Markov-modulated fluid flows. In the latter case, we use matrix-analytic methods to provide more explicit results. We conclude with some numerical illustrations.     

A dual bin-packing approach to scheduling surgical cases at a publicly-funded hospital

Publicly-funded hospitals are typically allocated an annual budget by the government based on the number of enrollees in the region. Given tight budget constraints, the capacity of resources is fairly fixed. Such hospitals strive to maximize the utilization of their resources through continuous improvement and optimization techniques. We address a surgical case scheduling problem experienced at a publicly-funded hospital and conceptualize this multi-period, multi-resource, priority-based case scheduling problem as an unequal-sized, multi-bin, multi-dimensional dual bin-packing problem. A mixed integer programming model and a heuristic based on the first fit decreasing algorithm are presented. Resource availability, case priorities, and variation in surgery times are key features included in our model. Our proposed approach led to substantial savings, 20% reduction in number of days and up to 20% increase in operating room utilization, when compared to real schedules obtained from the surgical department at a publicly-funded hospital.     

Similarity solutions of dispersive long-wave equations in two space dimensions

In this paper, both the direct method and the non-classical Lie approach are applied to reduce the (2 + 1)-dimensional dispersive long wave equations. Nine types of two-dimensional PDE reductions and 13 types of ODE reductions are given. All the known reductions obtained by the classical Lie approach are reobtained as some special cases. Similar to the (1 + 1)-dimensional case, some types of reductions with essential and logarithmic singular characteristic manifolds are allowed although the model is integrable.     

Dynamical networks: Continuous time and general discrete time models

Dynamical networks are characterized by 1) their topology (structure of the graph of interactions among the elements of a network); 2) the interactions between the elements of the network; 3) the intrinsic (local) dynamics of the elements of the network. A general approach to studying the commulative effect of all these three factors on the evolution of networks of a very general type has been developed in [1]. Besides, in this paper there were obtained sufficient conditions for a global stability (generalized strong synchronization) of networks with an arbitrary topology and the dynamics which is a composition (action of one after another) of a local dynamics of the elements of a network and of the interactions between these elements. Here we extend the results of [1] on global stability (generalized strong synchronization) to the case of a general dynamics in discrete time dynamical networks and to general dynamical networks with continuous time.     

The utility of nonequilibrium statistical mechanics,specifically transport theory,for modeling cohort data

This article introduces a new case‐based density approach to modeling big data longitudinally, which uses ordinary differential equations and the linear advection partial differential equations (PDE) to treat macroscopic, dynamical change as a transport issue of aggregate cases across continuous time. The novelty of this approach comes from its unique data‐driven treatment of cases: which are K dimensional vectors; where the velocity vector for each case is computed according to its particular measurements on some set of empirically defined social, psychological, or biological variables. The three main strengths of this approach are its ability to: (1) translate the data driven, nonlinear trajectories of microscopic constituents (cases) into the linear movement of macroscopic trajectories, which take the form of densities; (2) detect the presence of multiple, complex steady state behaviors, including sinks, spiraling sources, saddles, periodic orbits, and attractor points; and (3) predict the motion of novel cases and time instances. To demonstrate the utility of this approach, we used it to model a recognized cohort dynamic: the longitudinal relationship between a country's per capita gross domestic product (GDP) and its longevity rates. Data for the model came from the widely used Gapminder dataset. Empirical results, including the strength of the model's fit and the novelty of its results (particularly on a topic of such extensive study) support the utility of our new approach. © 2014 Wiley Periodicals, Inc. Complexity 20: 45–57, 2015     

Symmetries of explicit Runge-Kutta methods

A new (abstract algebraic) approach to the solution of the order conditions for Runge-Kutta methods (RK) and to the corresponding simplifying assumptions was suggested in Khashin (Can. Appl. Math. Q. 17(1), 555–569, 2009, Numer. Algorithm, 61(2), 1–11, 2012). The approach implied natural classification of the simplifying assumptions and allowed to find new RK methods of high orders. Here we further this approach. The new approach is based on the upper and lower Butcher’s algebras. Here we introduce auxiliary varieties ? _D and prove that they are projective algebraic varieties (Theorem 3.2). In some cases they are completely described (Theorem 3.5). On the set of the 2-standard matrices (Definition 4.4) (RK methods with the property b ₂ = 0) the one-dimensional symmetries are introduced. These symmetries allow to reduce consideration of the RK methods to the methods with c ₂ = 2c ₃/3, that is c ₂can be removed from the list of unknowns. We formulate a hypothesis on how this method can be generalized to the case b ₂ = b ₃ = 0 where two-dimensional symmetries appear.     

No Arbitrage and the Growth Optimal Portfolio

Abstract

Recently, several papers have expressed an interest in applying the Growth Optimal Portfolio (GOP) for pricing derivatives. We show that the existence of a GOP is equivalent to the existence of a strictly positive martingale density. Our approach circumvents two assumptions usually set forth in the literature: 1) infinite expected growth rates are permitted and 2) the market does not need to admit an equivalent martingale measure. In particular, our approach shows that models featuring credit constrained arbitrage may still allow a GOP to exist because this type of arbitrage can be removed by a change of numéraire. However, if the GOP exists the market admits an equivalent martingale measure under some numéraire and hence derivatives can be priced. The structure of martingale densities is used to provide a new characterization of the GOP which emphasizes the relation to other methods of pricing in incomplete markets. The case where GOP denominated asset prices are strict supermartingales is analyzed in the case of pure jump driven uncertainty.