Worker Decisions to Purchase Health Insurance

Studying worker health insurance choices is usually limited by the absence of price data for workers who decline their employer's offer. This paper uses a new Medical Expenditure Panel Survey file which links household and employer survey respondents, supplying data for both employer insurance takers and decliners. We test for whether out-of-pocket or total premium better explains worker behavior, estimate price elasticities with observed prices and with imputed prices, and test for worker sorting among jobs with and without health insurance. We find that out-of-pocket price dominates, that there is some upward bias from estimating elasticities with imputed premiums rather than observed premiums, and that workers do sort among jobs but this does not affect elasticity estimates appreciably. Like earlier studies with less representative worker samples, we find worker price elasticity of demand to be quite low. This suggests that any premium subsidies must be large to elicit much change in worker take-up behavior.     

Role of arterial smooth muscle tone and geometry in the regulation of peripheral conduit artery mechanics by shear stress

1. Although arterial blood flow is recognized as an important modulator of vascular tone and geometry, the effect of acute changes in shear-stress on conduit artery mechanics has not been fully investigated in humans because of technical limitations. 2. To assess, respectively, the effects of decreases and increases in flow and shear stress on radial artery tone and mechanics, arterial pressure (photoplethysmography), total blood viscosity, radial artery internal diameter, wall thickness (echotracking) and blood flow (Doppler) were measured in healthy volunteers (mean (+/-SEM) age 25 +/- 1 years) during a distal flow arrest (n=12) and hand skin heating (n=18). 3. Radial artery flow decreased from 31 +/- 4 to 7 +/- 1 10(-3) L/min during distal flow arrest (P < 0.001) and increased from 10 +/- 2 to 22 +/- 4 and 69 +/- 6 10(-3) L/min during heating (P < 0.001). At mean arterial pressure, these changes in flow were respectively associated with a parallel flow-dependent reduction and increase in diameter and midwall stress. There was no significant modification in mean elastic modulus. Compliance did not change when flow decreased and only increased at the highest level of flow. Finally, the cross-sectional compliance and incremental modulus were fitted as functions of midwall stress. The decrease in flow was associated with an upward shift of the modulus-midwall stress curve and a downward shift of the compliance-midwall stress curve. The increase in flow was associated with a downward shift of the modulus-midwall stress curve and an upward shift of the compliance-midwall stress curve at each level of wall shear stress. 4. By using two different procedures, we obtained similar results concerning the direct effects of increases and decreases in flow on stiffness of the arterial wall and on arterial compliance and demonstrated the presence of a flow-dependent regulation of arterial smooth muscle tone of peripheral conduit arteries in humans.     

高血压动脉弹性功能无创性评价的研究

动脉弹性的异常是原发性高血压发生、发展的血管病变特征之一。如何及早地发现血管早期改变、预测和干预高血压发生,已引起研究者们的广泛注意。现对高血压动脉弹性的无创性检测方法予以综述,以早期发现高血压发生发展过程中血管结构和功能的改变,并对这些患者进行危险分层,尽早进行一级预防,减少心血管事件的发生。     

新型钢丝弹力夹板的生物力学测试及临床应用研究

目的:钢丝弹力夹板是我们自行研制的,一种以钢丝为主要材料的夹板。取中医传统夹板帘子的优点,摒弃其在材料方面的局限性,而设计的一种新型夹板,本文通过对钢丝弹力夹板的生物力学测试及其临床应用研究去探讨钢丝弹力夹板的性能,为临床应用提供依据。方法:(1)取6套新型弹力钢丝夹板和6套柳木夹板,随机分为6组,每组由一套新型弹力钢丝夹板和一套柳木夹板组成。每组再随机编号,根据力学原则,不同力的作用下测量出两种夹板对应的纵向位移及其在撤销相应外力后两种夹板弹回后相应的残余位移,绘制相应曲线图,对其进行分析。(2)60例科雷氏骨折患者随机分为2组,钢丝弹力夹板组30例,柳木夹板组30例。经复位、固定后,分别在4 w后摄x线片观察骨折固定效果、患肢功能恢复情况、并以比正常骨折愈合时间提前多少为疗效判定标准评定疗效。比较两种夹板的临床效果。结果:新型钢丝弹力夹板强度及其弹性明显优于柳木夹板(P<0.05,P<0.01)。在治疗固定效果、患肢功能恢复(P<0.05,P<0.05)也优于传统柳木夹板。结论:新型钢丝弹力夹板是一种理想的外固定材料。     

低弹应力对钛合金植入物表面新骨形成的影响

目的观察应力作用下低弹β钛合金植入物表面新骨形成过程并探讨其对生物稳定的影响。方法选用20只成年新西兰大白兔,于双侧胫骨近端植入2种弹性模量(110GPa和30GPa)钛合金植入物,其中左侧为低弹组,右侧为高弹组,分别于术后4、8周处死动物,取材标本进行Micro-CT检测,测定BMD,BVF,SMI等指标,采用组织学方法,测定植入物-骨接触率(C)、单位面积新生骨百分比(S)以及生物力学最大拔出力。结果钛合金植入物植入后4周,组织学显示低弹组植入物表面新骨形成量多于高弹组,但2组之间差异无统计学意义;Micro-CT分析显示,2组之间BMD、BVF、SMI差异无统计学意义;生物力学最大拔出力检测低弹组为(74.60±6.59)N,高弹组为(63.30±8.41)N,2组之间差异存在统计学意义(P<0.05)。8周时组织学观察发现,低弹组植入物表面新骨形成量明显多于高弹组,植入物-骨接触率和单位面积新生骨百分比低弹组均优于高弹组;Micro-CTBMD、BVF、SMI分析显示低弹组材料表面成骨明显优于高弹组;低弹组的拔出力明显高于高弹组(P<0.01)。结论金属植入物的低弹特性有利于应力作用下植入物-骨界面的新骨形成,从而有利于提高植入物的生物稳定性。     

New data in the correction of twisted noses

Besides the numerous functional difficulties for the patient with a twisted nose, he must also handle its psychological repercussions. These repercussions are the cause of the frequent demands for purely aesthetic surgery. Correcting the twisted nose is difficult. There are the possible cutancous adhesions. Also, two classical factors are involved: septal, due to the clasticity of the cartilage; and the bone itself, due to ostectomies and/or osteotomies not performed or done incorrectly. Though the elasticity of the septal cartilage is corrected by many surgeons, few of them modify that of the alar cartilage. This is what we discuss in this article. We also discuss another element of major importance, the periosteum and its inextensibility.     

Skin–textile friction and skin elasticity in young and aged persons

Background/purpose: The mechanical properties of human skin are known to change with ageing, rendering skin less resistant to friction and shear forces, as well as more vulnerable to wounds. Until now, only few and contradictory results on the age-dependent friction properties of skin have been reported. This study has investigated in detail the influence of age on the friction of human skin against textiles.
Methods: In vivo skin-friction measurements on a force plate were combined with skin analyses concerning elasticity, hydration, pH value and sebum content. Thirty-two young and 28 aged persons rubbed their volar forearm in a reciprocating motion against various textiles on the force plate, using defined normal loads and sliding velocities, representing clinically relevant contact conditions.
Results: Mean friction coefficients ranged from 0.30 ± 0.04 (polytetrafluoroethylene) to 0.43 ± 0.04 (cotton/polyester). No significant differences in the friction properties of skin were found between the age groups despite skin elasticity being significantly lower in the aged persons. Skin hydration was significantly higher in the elderly, whereas no significant differences were observed in either skin pH value or sebum content.
Conclusion: Adhesion is usually assumed to be the dominant factor in skin friction, but our observations imply that deformation is also an important factor in the friction of aged skin. In the elderly, lower skin elasticity and skin turgor are associated with more pronounced skin tissue displacements and greater shear forces during frictional contact, emphasizing the importance of friction reduction in wound-prevention programmes.     

乳腺囊实性病变的超声诊断现状及新技术应用进展

乳腺囊实性病变是乳腺囊性病变中较常见的类型，其中恶性病变较多。常规超声联合超声诊断新技术如超声弹性成像、超声造影及三维超声成像等可提高对于乳腺囊实性病变的诊断准确率。本文就常规超声联合新技术在乳腺囊实性病变中的应用进行综述。     

实时二维剪切波弹性成像评价急性肝衰竭大鼠肝脏硬度

目的 探讨实时二维剪切波弹性成像（2D-SWE）对于检测大鼠急性肝衰竭（ALF）和指导预防性用药治疗的应用价值。方法 将28只雄性SD大鼠分为4组，即对照组（8只）、模型组（8只）、乳果糖组（6只）和美常安组（6只）。实验第1~8天，对美常安组予以美常安稀释后灌胃，乳果糖组予以乳果糖灌胃，对照组和模型组予以等量生理盐水。实验第6、7天，对模型组、乳果糖组和美常安组大鼠均腹腔注射硫代乙酰胺，对照组注射生理盐水。实验第8天，采用2D-SWE技术测量4组大鼠肝脏硬度值（LSM）。构建ROC曲线，根据AUC选出准确率最高的LSM进行组间比较。实验第9天，取大鼠肝组织行病理检查。结果 模型组主要病理表现为炎症、坏死；美常安组及乳果糖组炎症坏死程度较模型组减轻；对照组表现为正常肝组织。根据模型组LSM构建的ROC曲线中，平均值诊断效能最佳；以8.44 kPa为截断值，其AUC、敏感度和特异度分别为0.768、100%和62.50%。模型组LSM较其他3组明显升高（P均<0.05）。结论 ALF大鼠LSM增高。2D-SWE对检测ALF及预防性用药后疗效评估具有一定价值。     

超声弹性成像技术评估卒中后痉挛研究进展

超声弹性成像（UE）为新型超声诊断技术，通过直接测量弹性模量反映肌肉硬度变化，近年来逐渐用于定量评估卒中后痉挛（PSS）程度及指导治疗PSS。本文对UE评估PSS研究进展进行综述。