超声弹性成像与磁共振动态增强在乳腺肿瘤诊断中价值比较

目的：探讨超声弹性成像与磁共振动态增强成像在乳腺肿瘤诊断中应用价值。方法：收集2010年∽2013年来我院经临床及病理诊断为乳腺肿瘤140例患者的影像资料,其中乳腺癌62例,良性肿瘤78例,且术前均行动态增强及弹性成像检查,将所得图像信息进行分析,并与病理结果比较,分别获得弹性成像、动态增强及两者结合对乳腺癌诊断的敏感性、特异性、准确性。结果：所有病例均病理证实,磁共振动态增强检查诊断乳腺癌的敏感性为79%,特异性80.8%,准确性80%;超声弹性成像检查诊断乳腺癌的敏感性77.4%,特异性78.2%,准确性77.9%;两种方法结合检查诊断乳腺癌的敏感性91.9%,特异性91%,准确性91.4%;弹性成像、动态增强检查诊断乳腺癌结果比较无统计学差异（P〉0.05）;弹性成像、动态增强与两者联合的诊断结果比较有显著性差异（P〈0.05）。结论：磁共振动态增强和超声弹性成像结合对乳腺癌诊断的敏感性、特异性、准确性均明显高于单独一种检查。     

A simple and robust estimator for linear regression models with strictly exogenous instruments

In this paper, I investigate the estimation of linear regression models with strictly exogenous instruments under minimal identifying assumptions. I introduce a uniformly (in the data‐generating process) consistent estimator under nearly minimal identifying assumptions. The proposed estimator, called the integrated instrumental variables (IIV) estimator, is a simple weighted least‐squares estimator. It does not require the choice of a bandwidth or tuning parameter, or the selection of a finite set of instruments. Thus, the estimator is extremely simple to implement. Monte Carlo evidence supports the theoretical claims and suggests that the IIV estimator is a robust complement to optimal instrumental variables in finite samples. In an application with quarterly UK data, the IIV estimator estimates a positive and significant elasticity of intertemporal substitution and an equally sensible estimate for its reciprocal, in sharp contrast to instrumental variables methods that fail to identify these parameters.     

肝纤维化研究的热点及其展望

肝硬化严重威胁人类健康,肝纤维化阶段是大多数慢性肝病向肝硬化发展的必经阶段,目前多数研究认为肝纤维化阶段疾病尚可逆转,因此本文对肝纤维化研究的热点进行讨论,并展望其发展方向。     

不同运动步态下锁定加压钢板固定胫骨干骨折的有限元分析

背景：目前有限元分析广泛应用于人体骨折内固定模型的力学分析,但大多研究局限于静态下,动态下的骨折模型有限元分析尚未见报道。目的：通过三维有限元分析来探讨锁定加压钢板固定胫骨干不同类型骨折在不同运动步态下的应力分布情况。方法：利用CT扫描获得正常成人胫腓骨及足部的薄层扫描图像;运用相关软件建立其三维模型,在此模型上模拟出胫骨中段横行、斜行、粉碎性、螺旋形4种类型骨折,并与锁定钢板进行装配生成实验模型,各组模型加载相同的轴向压缩载荷600N。通过有限元分析软件Ansys12.0分别测定各组模型在落地相、中立相、离地相三种步态下的应力分布情况。结果与结论：在步态下,胫骨在骨折各组中的应力分布由小到大均为：落地相〈中立相〈离地相。锁定钢板在胫骨中段横行、斜行、粉碎性骨折中的应力分布由小到大均为：中立相〈落地相〈离地相;在胫骨中段螺旋形骨折中应力分布由小到大为：离地相〈中立相〈落地相;提示在运动步态中,钢板和胫骨均在离地相受力最大。钢板的应力集中在中间或边缘;而胫骨的应力分布在骨折线以上靠近近端,骨折线以下靠近骨折线。就胫骨整体而言,呈现两端集中,中间分散的状态。     

急性白血病患儿父母心理弹性影响因素的调查分析

目的探讨急性白血病患儿父母心理弹性水平及影响因素。方法采用心理弹性量表(CD-RISC),对某三甲医院小儿血液科两个病区于2014年12月-2015年1月期间住院的,符合纳入标准的急性白血病患儿父母进行调查。结果急性白血病患儿父母的心理弹性处于中等水平。心理弹性各维度得分以自强维度各条目得分最高,坚韧维度各条目得分最低。不同职业的白血病患儿父母的心理弹性水平不同,职业为农民的父母心理弹性及坚韧、自强维度得分最低。患儿父母与患儿不同亲子关系的心理弹性水平存在差异,在心理弹性及坚韧、自强维度上,母亲的得分均低于父亲。结论应对不同亲子关系和不同职业的父母进行针对的心理支持和健康教育,来自农村家庭的患儿母亲为重点关注对象。     

Behavior of Plain Concrete of a High Water-Cement Ratio after Freeze-Thaw Cycles

An experimental study of plain concrete specimens of water-cement ratio 0.55, subjected to 0, 15, 25, 40, 50 and 75 cycles of freeze-thaw was completed. The dynamic modulus of elasticity (DME), weight loss, compressive strength, tensile strength, flexural strength, cleavage strength and stress-strain relationships of plain concrete specimens suffering from freeze-thaw cycles were measured. The experimental results showed that the strength decreased as the freeze-thaw cycles were repeated. A concise mathematic formula between DME, weight loss, mechanical properties and number of freeze-thaw cycles was also established. The influences of freeze-thaw cycles on the DME, weight loss and mechanical properties were analyzed. The experimental results serve as a reference for the maintenance, design and life prediction of dams, hydraulic structures, offshore structures, concrete roads and bridges in cold regions.     

恶性实体瘤患儿家长心理弹性状况及相关因素的调查研究

目的探析不同恶性实体瘤患儿家长心理弹性差异,为建立有效可行的干预模型提供理论依据。方法选取2015年1-8月我院住院治疗的70例儿童恶性实体瘤患儿家长作为研究对象,釆用心理弹性量表(CD-RISC)及一般情况调查表对患儿家长进行问卷调查。较为全面地探析心理弹性的影响因素。结果患儿家长心理弹性各方面得分均低于中国社区人群平均值,更显著低于美国社区人群,患儿家长的心理弹性得分与其文化程度成正比;其工作状况会影响心理弹性得分,且非独生子女的家长心理弹性得分明显高于独生子女家长的心理弹性得分。结论心理弹性是个体心理健康的重要保护因子,恶性实体瘤患儿家长心理弹性状况为临床医护人员对患儿家长进行个体化的心理干预提供依据,以实现在患儿家长协助和影响下,患儿能接受并坚持治疗与护理。     

NEW TIMBER BRIDGE OVER THE SWAN RIVER AT FREMANTLE,WESTERN AUSTRALIA

Historical.

In the year 1862 the construction of a traffic bridge over the estuary of the Swan River at Fremantle, Western Australia, was commenced. This bridge, which was constructed of Jarrah (Euc. marginata) and entirely by convict labour, generally employed in chain gangs, was completed and opened for traffic in 1866.

In 1908, after 42 years' service, the bridge was reconditioned and at this time, 306 out of the 319 Jarrah piles were found to be in a sound and serviceable condition. Since its construction it has now given excellent service for over seventy years.

As this bridge lies on the main Perth-Fremantle highway, it receives heavy and continuous traffic, and in June, 1937. it was condemned and decided that a new bridge should be erected. Of recent years much controversy has existed with regard to the relative merits of timber versus steel and concrete for structural work, and it is interesting to note that after due consideration, the Western Australian Government approved of a timber design utilising principally local hardwoods. The estimated cost of the new bridge is in the vicinity of £60,000. while the cost of the alternative design for a steel and concrete structure would have involved an expenditure of approximately £180,000.