薄壁构件的高温低周疲劳寿命的预测与验证

提出了文题的计算模型,它采用非线性弹塑性蠕变有限元法,计算构件危险点在高温及周期保载的交变载荷谱作用下的应力应变响应,以应变范围区分法累积损伤,从而求出构件的疲劳寿命,并以带孔矩形薄板为例作了计算与验证,结果吻合较好,可供工程应用。     

Insecure Birth: A Qualitative Study of Everyday Violence During Pregnancy in Port au Prince,Haiti

Maternal and Child Health Journal - While the city offers economic opportunities for women in many countries, their safety and security remain vulnerable to urban violence, especially in poor...     

Diagnostic performances of shear-wave elastography for identification of malignant breast lesions: a meta-analysis

Purpose

To examine the performance of shear-wave elastography (SWE) for the differentiation of benign and malignant breast lesions using a meta-analysis.

Materials and methods

PubMed, Embase and the Cochrane library were searched for studies published up to January 2014. The references of retrieved relevant articles were reviewed to identify potential publications. Random-effect meta-analysis was conducted to assess the overall sensitivity and specificity of SWE in the differentiation of breast lesions.

Results

A total of 11 articles, including 2424 patients, were included in the present meta-analysis. The summarized sensitivity and specificity of the shear wave elastography performance based on maximum elasticity were 0.93 (95 % CI 0.91–0.95) and 0.81 (95 % CI 0.78–0.83), respectively. For the mean elasticity, the summarized sensitivity and specificity were 0.94 (95 % CI 0.92–0.96) and 0.71 (95 % CI 0.69–0.74), respectively. The summarized sensitivity and specificity were 0.77 (95 % CI 0.70–0.83) and 0.88 (95 % CI 0.84–0.91) for the SD of elasticity.

Conclusion

SWE has a high sensitivity and specificity in the differentiation of benign and malignant breast lesions. More large and prospective studies are warranted to further examine the performance of SWE.     

Decoronation of an ankylosed permanent incisor: alveolar ridge preservation and rehabilitation by an implant supported porcelain crown

Abstract –  Replacement resorption and ankylosis are frequently diagnosed following severe dental trauma. The complications that may develop as a result of ankylosis of a permanent incisor in children and adolescent include: esthetic compromise, orthodontic complications because of: arch irregularity; lack of mesial drift; tilting of adjacent teeth, arch length loss and local arrest of alveolar ridge growth. To avoid such complications, an ankylosed tooth should be removed before the changes become so pronounced that they compromise future prosthetic treatment. The purpose of this article was to present a case of preservation of the alveolar ridge for implant rehabilitation by utilizing decoronation for the treatment of a young permanent central incisor. An implant was inserted, without any bone augmentation procedures, followed by prosthetic porcelain crown rehabilitation. We conclude that treatment of an ankylosed young permanent incisor by decoronation may maintain the alveolar bone ridge width, height and continuity, and facilitate future rehabilitation with minimal, if any, ridge augmentation procedures.     

Normalization of hematocrit in hemodialysis patients with cardiac disease does not increase blood pressure

Since the earliest reports of the use of Epoetin alfa in hemodialysis patients, it has been described that Epoetin alfa may exacerbate preexisting hypertension or induce hypertension in End Stage Renal Disease (ESRD) patients not previously hypertensive. We undertook this study to determine if the correction of anemia in ESRD patients with cardiac disease from a hematocrit of 30+/-3% to 42+/-3% with the use of Epoetin alfa would result in increased blood pressure. This study was a substudy of the "Normal hematocrit Study". METHODS: Thirty-one patients were randomized into one of two arms. Patients in Group A had their hematocrit increased with the use of slowly escalating doses of Epoetin alfa to 42+/-3% and patients in Group B were maintained with a hematocrit of 30+/-3% throughout the course of the study. All patients had their blood pressure recorded with a 24 hour ambulatory BP device at study entry and at 28 weeks following randomization when they had achieved their target hematocrit. Pre-dialysis systolic and diastolic BP was also recorded. RESULTS: The mean hematocrit increased in Group A from 29.1+/-2.4% to 40.8+/-5.2% after 30 weeks. The hematocrit in Group B remained stable at 30+/-3% throughout the course of the study. There was no difference in mean daytime, mean nighttime or 24 hour systolic or diastolic blood pressure between Groups A and B at either baseline or follow-up. Neither was there a difference in mean pre-dialysis systolic or diastolic BP between Groups A or B at baseline or Follow-up. Four patients in Group A and 4 patients in Group B required an increase in their antihypertensive medication during the course of the study. CONCLUSION: It is possible to increase hematocrit to normal levels in hemodialysis with the administration of Epoetin alfa. The increase in hematocrit from 30+/-3% to 42+/-3% is not associated with increased blood pressure.     

Initial experience with a new method for the dynamic assessment of pelvic floor function in women: the Kolpexin Pull Test

The aim of this study was to evaluate a newly developed, simple test for assessing pelvic floor muscular function in women. Pelvic floor strength in women with symptomatic pelvic floor dysfunction was evaluated with a newly developed assessment tool, the Kolpexin Pull Test, and compared to a clinically validated digital pelvic floor strength assessment scale (DPA). A 36-mm Kolpexin sphere was inserted into the vagina above the levator plate and connected to a digital tensiometer/force gauge. The force required to remove the sphere was recorded for three resting trials and three maximum pelvic floor contractions. Results of the DPA and Kolpexin Pull Test were analyzed using ANOVAs of contrast variables, intraclass correlations, and regression analyses. Twenty-one women participated in the study. Age range was 36–85 years, parity range was 2–5. All six trials required less than 5 min to perform in each patient. Intraperson maximum contraction data were correlated at 0.96 (95% CI: 0.91, 0.98), and were greater at higher DPA scores (p=0.016). There were positive correlations between the maximum contraction and DPA data (adjusted R²=0.52; p <0.001), and the maximum contraction minus resting vs DPA data (adjusted R²=0.54; p< 0.001). The Kolpexin Pull Test is reproducible, rapid, and correlates with digital clinical assessment of pelvic floor strength during maximal contractions.Abbreviations DPA Digital pelvic assessment - MC Maximum pelvic floor contraction - RP Relaxed pelvic floor Editorial Comment: This paper is an interesting pilot study of a new technique to measure pelvic muscle strength. Several other techniques have already been described. As the authors have stated, all methods have flaws, including the relatively easy and reproducible digital pelvic assessment (DPA). The Kolpexin sphere offers the hope of more objective testing than the DPA, overcomes the contribution of Valsalva to the pressure perineometry readings, and is easier to perform than ultrasound or EMG. The authors did not fully convince us of the objectivity of the measurements, as the study was not blinded. Also, we do not know whether the size of the sphere altered the readings in women in different heights and/or weights. If, on further testing, this technique is shown to have inter- as well as intraexaminer reproducibility, it may contribute to the evaluation of patients for management as well as for research.     

CT灌注结合醋甲唑胺负荷试验对32周龄原发性高血压大鼠脑血管储备功能的初步研究

目的：探讨CT灌注结合醋甲唑胺负荷试验评估原发性高血压大鼠（spontaneous hypertensive rat,SHR）脑血管储备功能变化的可行性,并与病理实验结果对照,评价其对亚临床期脑缺血患者的临床应用价值。方法：正常对照组、SHR组各10只行常规脑CT灌注扫描及醋甲唑胺灌胃后1.5~2.0 h脑CT灌注扫描,测量负荷前后感兴趣区脑血容量（cerebral blood volume,CBV）、脑血流量（cerebral blood flow,CBF）、平均通过时间（mean transit time,MTT）及达峰时间（time to peak,TTP）值,并作统计学分析;光镜下观察大鼠脑石蜡HE染色切片小动脉管壁厚度、微循环毛细血管网情况,通过TTC染色明确各组大鼠脑组织有无脑梗死灶。结果：CT灌注扫描：两组大鼠负荷前后自身比较,正常组CBV、CBF、MTT、TTP值差异均有统计学意义（P＆lt;0.05）,且负荷状态下CBV、CBF值增加,MTT、TTP值缩短;SHR组差异均无统计学意义。组间比较,两组大鼠负荷前后CBV、CBF、MTT、TTP值差异均有统计学意义（P＆lt;0.05）,且SHR大鼠CBV、CBF值减低,MTT、TTP值延长。 HE染色示SHR组小动脉及微小动脉管壁重塑,管壁增厚、硬化,微循环毛细血管网数目相对减少。TTC染色示SHR大鼠脑组织无明确脑梗死灶。结论：SHR较正常大鼠脑血管储备减低,醋甲唑胺负荷CT灌注成像可反映脑血管储备功能改变,对亚临床期脑缺血患者的病情评估具有重要临床指导意义。     

Reversible phenotypic modulation induced by deprivation of exogenous essential fatty acids

Essential fatty acid deficiency, produced by deprivation of omega-6 and omega-3 fatty acids, is a condition characterized by renal disease, dermatitis, and infertility. Although many of the biochemical aspects of this disorder have been investigated, little is known about the ultrastructural changes induced by essential fatty acid deficiency. Using a unique fatty acid-deficient cell line (EFD-1), which demonstrates the in vivo fatty acid changes of essential fatty acid deficiency, and the prostaglandin E2-producing mouse fibrosarcoma line from which it was derived (HSDM1C1), we correlated ultrastructural and biochemical changes induced by prolonged deprivation of all exogenous lipids and subsequent repletion of selected essential fatty acids. We found that in cells deprived of all exogenous lipids, there was dilation of rough endoplasmic reticulum and an associated defect in protein secretion; these changes were specifically reversed by arachidonate. There was also an accumulation of secondary lysosomes containing degraded membranes in these cells with an associated increase in phospholipids relative to parent HSDM1C1 cells. Cytoplasmic lipid bodies present in parent cells disappeared, with an associated decrease in triacylglycerol. After just 2 days in lipid-free medium, all these changes were apparent, and prostaglandin E2 production was markedly impaired despite normal amounts of cellular arachidonate. Incubation of EFD-1 cells with arachidonate, the major prostaglandin precursor fatty acid, induced a reversion to the HSDM1C1 phenotype, whereas other fatty acids were totally ineffective. These results indicate changes in fatty acid metabolism in essential fatty acid deficiency are associated with marked alterations in ultrastructure and secretion of protein from cells.     

Prolonged storage of tissues at low temperatures does not preclude their use for ultrastructural studies.

A cost-effective method for electron microscopic study of snap-frozen surgical specimens is described. The method is available to any surgical pathology laboratory equipped with a deep freezer and allows the performance of ultrastructural observations on archival material.     

遗忘型轻度认知障碍的脑白质纤维束成像研究

目的：应用纤维束成像术研究遗忘型轻度认知功能障碍(aMCI)患者脑白质细微结构的改变。方法对30例经临床诊断的 aMCI 患者和31例正常对照(NC)组行扩散张量成像,用 dTV II 软件重建出扣带束、胼胝体、钩状束及下枕额束,并沿着白质束测量部分各向异性(FA)值。对比分析 aMCI 组与 NC 组各白质束的 FA 值,并将 aMCI 组的 FA 值与简易智能精神状态检查量表(MMSE)评分进行相关性分析。结果①aMCI 组的两侧扣带束、两侧钩状束及胼胝体 FA 值明显低于 NC 组,差异有统计学意义;左侧下枕额束 FA 值低于 NC 组,但差异无统计学意义。②右侧扣带束的 FA 值与 MMSE 评分呈正相关。结论aMCI 患者扣带束、钩状束及胼胝体 FA 值的异常改变,提示在阿尔茨海默病(AD)的前驱阶段存在与记忆相关的脑白质束的微损害,纤维束成像(tractography)技术对脑白质的早期损害具有很高的敏感性。