Ultrasound in prenatal diagnosis: polemics around routine ultrasound screening for second trimester fetal malformations

Ultrasound for routine fetal malformation screening has been polemical from its early beginning because of the very broad range of diagnosis rates disclosed, i.e. from 13% to 82%, average 27.5%. A review of available studies is proposed to assess objectively the efficacy of ultrasound, considering also economical, ethical and methodological aspects as influential factors for choosing a routine screening policy. The utility of fetal malformation diagnosis before birth is brought forward, including second opinion, karyotyping, poly-disciplinary case discussion prior to management. Method and material of reviewed studies considerably vary and might influence the sensitivity results, as the choice of the population sample and selection of pregnant women, gestation age at screening, distribution of malformation among systems or tracts, exclusion of some fetal malformation and the routine practice of autopsy. Efficiency of screening studies is compared, and among them Radius and Eurofetus studies. Average sensitivity is finally considered as satisfactory in the daily practice when operated by trained personnel. The importance of additional factors for successful screening are emphasized such as education, equipment quality and fetal ultrasound examination at different gestation age for a better understanding of natural history of fetal morphology. Copyright © 2002 John Wiley & Sons, Ltd.     

The first trimester ‘combined test’ for the detection of Down syndrome pregnancies in 4939 unselected pregnancies

The high detection rate (DR) for Down syndrome (DS) pregnancies which can be achieved by measuring fetal nuchal translucency (NT) early in pregnancy can be improved by combining it with placental hormones [pregnancy-associated plasma protein A (PAPP-A) and free β-human chorionic gonadotrophin (fβ-hCG)] and maternal age (‘combined test’). In this study we wanted to assess the DR using the ‘combined test’ in an unselected population of self-referred pregnant women at a false-positive rate (FPR) of about 5%. NT, PAPP-A, fβ-hCG and maternal age were measured in all women with singleton pregnancies who booked for delivery in our hospital from 1 December 1997 to 31 April 2000 and who were between 10 and 13 completed weeks of gestation [crown–rump length (CRL) 35–70 mm]. The specific DS risk was calculated using the computer program Alpha Version 5aa (Logical Medical Systems, London, UK). A total of 4939 women were tested. Out of 14 DS pregnancies that occurred during this period of time, 12 were detected with the test. A total of 246 women had a false-positive test result in a non-DS pregnancy (FPR 5.0%). This makes the ‘combined test’ by far the best test for the detection of DS pregnancies in a low-risk population. The constant increase in maternal age at the time of delivery can also lead to an improved DR if a simple age-dependant protocol for DS detection is used, but only at the price of a much higher number of amniocenteses and subsequent abortions. The DR for DS can be increased much more markedly using the ‘combined test’ with a FPR that still remains at the level as it was in the early 1970s. Copyright © 2002 John Wiley & Sons, Ltd.     

Preparation and activation: determinants of age at reproductive maturity in male baboons

Age at maturity is a particularly important life history trait, but maturational data are rare for males in natural populations of mammals. Here we provide information on three maturational milestones and their social and demographic correlates among 43 wild male baboons, Papio cynocephalus, in a natural population in Amboseli National Park, Kenya. We examined (1) age at testicular enlargement, which signals puberty and the onset of subadulthood, (2) age at attainment of adult dominance rank, which we consider to be the beginning of adulthood, and (3) age at first sexual consortship, which is the best measure available for age at first reproduction in male baboons. Testicular enlargement (median age = 5.69 years) occurred earlier among sons of high ranking mothers, and was not influenced by rainfall or seasonality. Attainment of adult dominance rank (median age = 7.41 years) was also accelerated among sons of high-ranking mothers, and among males whose mothers had died while the males were juveniles. First sexual consortship (median age = 7.92 years) was not influenced directly by maternal characteristics, but attainment of adult dominance rank always preceded first consortship. The lag time between attainment of adult rank and first consortship (median = 2.5 months; range = 5–526 days), was predicted by the number of sexually cycling females in the group when the male attained rank, and by how high ranking the male became in his first months as an adult. We suggest that the age at which a male baboon is ready to begin reproducing is influenced by a relatively stable maternal characteristic that exerts its influence early in development, but the timing with which this potential is realized depends on activation by more proximate, often stochastic triggers such as female availability. This two-level organization of influences is likely to contribute to the variance both in age at first reproduction and in lifetime fitness. Differences in the relative magnitude of the two levels will lead to both intra- and interspecific variability in the opportunity for maternal selection and sexual selection.     

磁粉在一级强化混凝中的试验研究

在一级强化混凝实验的基础上.研究了磁粉的加入对强化混凝沉淀效果的影响,并确定出最佳温度的范围和最佳加药量.通过大量的试验证明了磁粉的加入对混凝沉淀有很强的促进作用,在一定程度上提高了出水的水质.     

Constructing change: The evolution of land and resource management in Alberta,Canada

Recognizing the limitations common to both centralized and privatized management regimes, institutionalized resource management is beginning to incorporate the knowledge and skills of local resource users, coupled with the enabling policies and legislation of state systems, to arrive at cooperative approaches to resource management. These varying and dynamic approaches to resource management have been compelled largely through the recognition of the limited capabilities of existing management systems to adapt effectively to ecosystem change and the evolving needs of resource users. These cooperative approaches to management should not, however, be considered an institutional end-point, but rather a phase in the perpetual transition of a social system; each unique in character and individually variable depending on the resource being managed, the political climate in which management occurs, as well as the differing strategies employed by resource users to enact institutional change. Drawing from the experiences of the Whitefish Lake First Nation of Alberta, Canada, this paper presents a brief overview of the evolution of resource management theory, grounded in the real-world formation of the Whitefish Lake First Nation — Province of Alberta Cooperative Management Agreement.     

城市污水厂初沉池的设置方式及运行效果

跟据初沉池在城市污水厂长期的实际运行数据,分析了初沉池去除污水中的悬浮物、有机物、降低能耗、降低水质波动对生化系统的冲击等方面所起的作用,设置初沉池还有利于提高生化系统污泥的活性成份（MLVSS／MLSS）、增强出水效果;同时探讨了初沉池在城市污水处理中的设置方式,通过设置超越管线,在冬、夏季水质波动较大,保持生化系统进水有机负荷的稳定,提出了优化初沉池的处理效果的运行方式。