Twin pregnancies in Cardiff and Vale of Glamorgan over four decades: natural twinning is on the increase

Objective

To assess trends in twinning over four decades using a population-based registry.

Design

Ecological study to conduct trend analysis of twin pregnancies in a geographically defined area over 40 years.

Setting

All pregnancies in the Cardiff and Vale of Glamorgan area of South Wales from 1965 to 2004, as recorded in the Cardiff Birth Survey (CBS) database.

Methods

Trends of the incidence of all twin pregnancies (≥18 weeks of gestation) were calculated in 5-year increments, beginning with 1965–1969 and ending in 2000–2004. Natural twinning rates could only be calculated for the terminal five time periods (i.e., 1980–1984, 1985–1989, 1990–1994, 1995–1999, and 2000–2004), when information regarding non-spontaneous (iatrogenic) twinning was first collected in the database. All results were adjusted for maternal age.

Results

The total twinning rate was 13.1 per 1000 pregnancies in the 1st time period (1965–1969). Subsequently, there was a gradual reduction in twinning, reaching a nadir of 10.3 per 1000 for the time period 1980–1985 (Z = 3.15, P value < 0.001). This was followed by a gradual increase in twinning, reaching a maximum of 15.7 per 1000 for both 1995–1999 and 2000–2004 (Z = −5.18, P value < 0.0001). After exclusion of the cases of iatrogenic pregnancies, the natural twinning rate showed a continuous and gradual increase from 10 per 1000 spontaneous pregnancies in 1980–1984 to 13.3 per 1000 in 2000–2004 (Z = −5.08, P value < 0.0001).

Conclusion

The data showed a gradual, continuous increase in natural twinning rates over the last two decades. Such an increase cannot be attributed to the rise in maternal age alone.     

Natural IVF cycles may be desirable for women with repeated failures by stimulated IVF cycles

Purpose Although many reports support stimulated in vitro fertilization, several patients do not respond to it well. Furthermore, stimulated treatment could be associated with reduced ovarian response. We describe three successful cases involving patients of advanced age from whom dominant follicles were retrieved during the natural cycle. Materials and methods All patients had failed to bear children through stimulated in vitro fertilization. In case 1, a follicle was retrieved after a gonadotropin-releasing hormone agonist was used to induce luteinizing hormone surge. In cases 2 and 3, pregnancy was achieved via completely natural cycles. Results One embryo was transferred every 16 cycles. Ongoing pregnancy—defined as pregnancy progressing beyond gestation week 9—was established in three cycles. The patients successfully delivered and had uneventful neonatal courses. Conclusion Mature oocyte retrieval followed by natural rather than stimulated in vitro fertilization might be a potential treatment for patients of advanced age when stimulated in vitro fertilization has been repeatedly unsuccessful. Capsule We describe three successful pregnancies and deliveries achieved via natural IVF cycles: the patients were older than 37 years with repeated failures by stimulated IVF.     

课堂教学语言艺术

本文针对中等医学教育的特点，对课堂教学语言艺术的概念、意义、要求和特征以及它对教学信息传递所起的作用、效果作了论述，说明教师要创造教学语言艺术，用之于优化教学目标。     

天然抗氧化剂在医药领域的研究进展

天然抗氧化剂可以治疗预防多种疾病,进而本文阐述了自然界中天然抗氧化剂的来源、结构类型和作用机理,探讨了天然抗氧化剂在医药领域未来的研究发展前景。     

在Excel中使用VBA编程处理RDS抽样调查数据

Excel是Office办公软件中的一员,其强大的数据处理功能使其在数据表处理方面占有非常重要的地位,特别是可以使用VBA进行编程来处理更加复杂的数据,针对RDS抽样调查数据如何处理进行了探索。     

制备前后时间对艾滋病患者CD4＋、CD8＋计数的影响

目的：了解血样制备前后放置时间对艾滋病患者外周血CD4^＋、CD8^＋、细胞计数的影响.方法：用艾滋病患者外周血分别在室温放置6、24、48及72 h后进行样品制备,流式细胞仪检测CD4^＋、CD8^＋细胞绝对计数;以及样品制备后分别在2、24、48、72及168 h上机检测;结果用SPSS软件进行统计学分析.结果：血液在室温放置72 h之内制备,CD4^＋细胞计数变化差异无统计学意义（P＞0.05）,CD8^＋细胞计数72 h与6 h比较差异有统计学意义（P＜0.05）;血样制备后室温放置1周内CD4^＋、CD8^＋细胞计数差异无统计学意义（P＞0.05）.结论：血液制备前在室温放置72 h后CD8^＋细胞计数有明显变化;血样立即制备后室温放置1周CD4^＋、CD8^＋细胞计数是相对稳定的.     

数字化口腔内窥镜的设计与实现

以梯度折射率透镜（自聚焦透镜）为摄像镜头，通过光电转换，结合数字信号处理和数据库技术．设计并实现了数字化口腔内窥镜。临床应用表明，所研制的自聚焦口腔内窥镜不仅操作简单、成像清晰且便于对患者的各种信息进行管理、查询，有望成为牙科医生必备的一种新诊疗设备。     

Using measures of reading time regularity (RTR) to quantify eye movement dynamics,and how they are shaped by linguistic information

In this article, we present the concept of reading time regularity (RTR) as a measure to capture reading process dynamics. The first study is concerned with examining one of the assumptions of RTR, namely, that process measures of reading, such as eye movement fluctuations and fixation durations, exhibit higher regularity when contingent on sequentially structured information, such as texts. To test this, eye movements of 26 German native speakers were recorded during reading-unrelated and reading-related tasks. To analyze the data, we used recurrence quantification analysis and sample entropy analysis to quantify the degree of temporal structure in time series of gaze steps and fixation durations. The results showed that eye movements become more regular in reading compared to nonreading conditions. These effects were most prominent when calculated on the basis of gaze step data. In a second study, eye movements of 27 native speakers of German were recorded for five conditions with increasing linguistic information. The results replicate the findings of the first study, verifying that these effects are not due to mere differences in task instructions between conditions. Implications for the concept of RTR and for future studies using these metrics in reading research are discussed.     

Effect of Microwave-Assisted Synthesis and Sintering of Lead-Free KNL-NTS Ceramics

Lead-free piezoelectric powders (K_0.44Na_0.52Li_0.04)(Nb_0.82Ta_0.10Sb_0.04)O₃ were obtained by conventional and microwave-assisted reactive heating. Firstly, the synthesis of the material was carried out following the mixed oxide route and employing both traditional methods and microwave technology. Thermogravimetry, X-ray diffraction, field emission scanning electron microscopy and electrical properties analyses were evaluated. X-ray diffraction of the powders calcined by the microwave process shows the formation of perovskite structure with orthorhombic geometry, but it is possible to observe the presence of other phases. The presence of the secondary phases found can have a great influence on the heating rate during the synthesis on which the kinetics of the reaction of formation of the piezoelectric compound depend. The calcined powder was sintered at different temperatures by conventional and non-conventional processes. The microstructure of the ceramics sintered by microwave at 1050 °C for 10 min shows perovskite cubes with regular geometry, of size close to 2–5 µm. However, the observed porosity (~8%), the presence of liquid phase and secondary phases in the microstructure of the microwave sintered materials lead to a decrease of the piezoelectric constant. The highest d₃₃ value of 146 pC/N was obtained for samples obtained by conventional at 1100 °C 2 h compared to samples sintered by microwave at 1050 °C 10 min (~15 pC/N).     

Sleep-Specific Processing of Auditory Stimuli Is Reflected by Alpha and Sigma Oscillations

Recent research revealed a surprisingly large range of cognitive operations to be preserved during sleep in humans. The new challenge is therefore to understand functions and mechanisms of processes, which so far have been mainly investigated in awake subjects. The current study focuses on dynamic changes of brain oscillations and connectivity patterns in response to environmental stimulation during non-REM sleep. Our results indicate that aurally presented names were processed and neuronally differentiated across the wake-sleep spectrum. Simultaneously recorded EEG and MEG signals revealed two distinct clusters of oscillatory power increase in response to the stimuli: (1) vigilance state-independent θ synchronization occurring immediately after stimulus onset, followed by (2) sleep-specific α/σ synchronization peaking after stimulus offset. We discuss the possible role of θ, α, and σ oscillations during non-REM sleep, and work toward a unified theory of brain rhythms and their functions during sleep.SIGNIFICANCE STATEMENT Previous research has revealed (residual) capacity of the sleeping human brain to interact with the environment. How sensory processing is realized by the neural assemblies in different stages of sleep is however unclear. To tackle this question, we examined simultaneously recorded MEG and EEG data. We discuss the possible role of θ, α, and σ oscillations during non-REM sleep. In contrast to versatile θ band response that reflected early stimulus processing step, succeeding α and σ band activity was sensitive to the saliency of the incoming information, and contingent on the sleep stage. Our findings suggest that the specific reorganization of mechanisms involved in later stages of sensory processing takes place upon falling asleep.