Maternal age specific rates for all major chromosome aberrations have been determined in 52 965 pregnancies in mothers 35 years of age and over at the time of amniocentesis. Rates increase exponentially with advancing maternal age for trisomies 21, 18 and 13, and for the XXX and XXY syndromes, but in the autosomal trisomies this rise appears to be followed by a levelling off at the upper end of the age range. A significant inverse relationship with maternal age is found for 45,X cases. It is postulated that these various patterns are the result of the interaction of three principal factors: a maternal age effect acting particularly on first meiotic nondisjunction: a higher spontaneous abortion rate with advancing maternal age for aneuploid as compared to euploid conceptions; and an increased probability of spontaneous abortion before the time of amniocentesis for conceptions with more extensive chromosome imbalance. A stepwise logistic regression analysis of 13 299 pregnancies in which both parental ages are known shows that the father's age does not influence these maternal age specific rates, with the possible exception of the 47,XXY syndrome. 相似文献
ABSTRACT Residential satisfaction is a vital component of individual quality of life which has been explored by researchers from different perspectives. This study takes the stance to investigate residential satisfaction from sociodemographic standpoints. The purpose is to contribute to further research on residential satisfaction by exploring specifically the impact of age, gender and marital status on overall residential satisfaction and in more detail with components of residential satisfaction of residents living in apartment buildings in Dhaka, Bangladesh. Quantitative analyses of a survey of 204 residents living 59 apartment buildings in Dhaka was conducted to examine whether there is any relation between residential satisfaction with age, gender and marital status of the apartment dwellers. This study also examined if these sociodemographic characteristics had a moderator effect on some of the key components of residential satisfaction. Primary findings indicate that there exists a significant relationship between residential satisfaction with age, gender, and marital status. Further analysis revealed that the “Married” group was more satisfied than the “Single/Never married” group, senior people tend to be more satisfied than are younger respondents and females were more satisfied than males concerning overall residential satisfaction. This study concludes that potential sociodemographic differences among households in apartment developments in Dhaka should be considered for effective residential satisfaction and to create a socially sustainable living environment. 相似文献
Abstract: Apparent ground‐water ages as determined by the noble gas isotope 85Kr and the water isotope 3H are compared. Refined gas extraction methodology at the wellhead permits efficient collection of Kr for 85Kr isotope enrichment. 85Kr isochrones elucidate areas of much younger ground‐water ages than 3H. Declining 3H activities in the catchment prevent its correlation with the youngest measured 85Kr ages. Source water for most drinking water supplies in the Collyer River catchment is recharged within 40 years BP (2004). Mean‐age (τ) transport modeling suggests uncertainty of ground‐water ages is greatest in the central basin area. 相似文献
Objective: This study investigated drivers' evaluation of a conventional autonomous emergency braking (AEB) system on high and reduced tire–road friction and compared these results to those of an AEB system adaptive to the reduced tire–road friction by earlier braking. Current automated systems such as the AEB do not adapt the vehicle control strategy to the road friction; for example, on snowy roads. Because winter precipitation is associated with a 19% increase in traffic crashes and a 13% increase in injuries compared to dry conditions, the potential of conventional AEB to prevent collisions could be significantly improved by including friction in the control algorithm. Whereas adaption is not legally required for a conventional AEB system, higher automated functions will have to adapt to the current tire–road friction because human drivers will not be required to monitor the driving environment at all times. For automated driving functions to be used, high levels of perceived safety and trust of occupants have to be reached with new systems. The application case of an AEB is used to investigate drivers' evaluation depending on the road condition in order to gain knowledge for the design of future driving functions.
Methods: In a driving simulator, the conventional, nonadaptive AEB was evaluated on dry roads with high friction (μ = 1) and on snowy roads with reduced friction (μ = 0.3). In addition, an AEB system adapted to road friction was designed for this study and compared with the conventional AEB on snowy roads with reduced friction. Ninety-six drivers (48 males, 48 females) assigned to 5 age groups (20–29, 30–39, 40–49, 50–59, and 60–75 years) drove with AEB in the simulator. The drivers observed and evaluated the AEB's braking actions in response to an imminent rear-end collision at an intersection.
Results: The results show that drivers' safety and trust in the conventional AEB were significantly lower on snowy roads, and the nonadaptive autonomous braking strategy was considered less appropriate on snowy roads compared to dry roads. As expected, the adaptive AEB braking strategy was considered more appropriate for snowy roads than the nonadaptive strategy. In conditions of reduced friction, drivers' subjective safety and trust were significantly improved when driving with the adaptive AEB compared to the conventional AEB. Women felt less safe than men when AEB was braking. Differences between age groups were not of statistical significance.
Conclusions: Drivers notice the adaptation of the autonomous braking strategy on snowy roads with reduced friction. On snowy roads, they feel safer and trust the adaptive system more than the nonadaptive automation. 相似文献