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11.
Gaze is one of the main means of communication in young infants, and it has been shown to be important for subsequent socio‐emotional and cognitive development. Maternal depression is a well‐known risk factor for disrupting mother–infant interactions, but findings regarding gaze behavior in infants of depressed versus nondepressed mothers have been ambiguous. In this study, we examined gaze duration and activity in a sample of 27 infants of mothers with postpartum depression (PPD) and 49 infants of nondepressed mothers. Maternal depressive symptoms were assessed with the Edinburgh Postnatal Depression Scale, and diagnoses were confirmed in clinical interview. Infant gaze was assessed during 4‐month face‐to‐face interactions using continuous timed‐event coding with high temporal resolution. Although we found no differences in gaze duration, infants of PPD mothers had both significantly less Gaze On and also less Gaze Off events. Findings suggest that PPD is related to reduced gaze activity during mother–infant interaction in 4‐month‐olds. This reduced activity may have long‐term negative consequences for child development.  相似文献   
12.
This article charts the development of welfare‐to‐work policies and compares and contrasts the traditions of delivery in the UK and Australia. We find that in the UK, employment services and social security benefit administration have been dominated by the central state, traditionally affording a key role to civil servants as direct delivery agents. However, in federal Australia, mixed economies of welfare‐to‐work operate in the different states, there is a far greater role for social services and non‐profit organizations are firmly established as key providers of frontline employment services. Since the late 1990s, UK welfare reforms have been gradually following the Australian lead in contracting non‐state actors as delivery agents. As this trend seems set to continue and intensify, we examine the Australian experience in order to reflect on the role of non‐profits in policy reform.  相似文献   
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This experiment explored whether or not 2‐year‐olds would engage in synchronic imitation with human hands. Sixty‐four 24‐month‐old infants participated. In a test of synchronic imitation, infants were given a toy while a model simultaneously performed novel actions on an identical toy. Infants were randomly assigned to 1 of 4 model conditions: a familiar person, an unfamiliar person, disembodied human hands, and disembodied robotic pincers. Infants were as likely to synchronically imitate disembodied hands as a person. Imitation of the pincers was significantly lower. This pattern suggests that 2‐year‐olds will engage socially with human hands in the absence of the rest of the body.  相似文献   
15.
This paper provides a means of accurately simulating explosive autoregressive processes and uses this method to analyze the distribution of the likelihood ratio test statistic for an explosive second-order autoregressive process of a unit root. While the standard Dickey-Fuller distribution is known to apply in this case, simulations of statistics in the explosive region are beset by the magnitude of the numbers involved, which cause numerical inaccuracies. This has previously constituted a bar on supporting asymptotic results by means of simulation, and analyzing the finite sample properties of tests in the explosive region.  相似文献   
16.
The aging domestic oil production infrastructure represents a high risk to the environment because of the type of fluids being handled (oil and brine) and the potential for accidental release of these fluids into sensitive ecosystems. Currently, there is not a quantitative risk model directly applicable to onshore oil exploration and production (E&P) facilities. We report on a probabilistic reliability model created for onshore exploration and production (E&P) facilities. Reliability theory, failure modes and effects analysis (FMEA), and event trees were used to develop the model estimates of the failure probability of typical oil production equipment. Monte Carlo simulation was used to translate uncertainty in input parameter values to uncertainty in the model output. The predicted failure rates were calibrated to available failure rate information by adjusting probability density function parameters used as random variates in the Monte Carlo simulations. The mean and standard deviation of normal variate distributions from which the Weibull distribution characteristic life was chosen were used as adjustable parameters in the model calibration. The model was applied to oil production leases in the Tallgrass Prairie Preserve, Oklahoma. We present the estimated failure probability due to the combination of the most significant failure modes associated with each type of equipment (pumps, tanks, and pipes). The results show that the estimated probability of failure for tanks is about the same as that for pipes, but that pumps have much lower failure probability. The model can provide necessary equipment reliability information for proactive risk management at the lease level by providing quantitative information to base allocation of maintenance resources to high-risk equipment that will minimize both lost production and ecosystem damage.  相似文献   
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This study tested the association between mother’s early age at first birth and various life outcomes for her children in later adolescence and early adulthood. Data were analyzed from the Rochester Youth Development Study, an ongoing panel study of adolescents enrolled in seventh or eighth grade in Rochester Public Schools in 1988 (N =729). Boys born to mothers who began childbearing before age 19 had elevated risks of drug use, gang membership, unemployment, and early parenthood. Girls born to young mothers only had elevated risks of early parenthood. Of the mediators tested, low maternal education had the largest mediating effects. The findings suggest that the risks associated with being born to a young mother are substantial but perhaps disproportionately so for boys.  相似文献   
19.
This paper analyses the likelihood ratio test for the hypothesis of reduced cointegration rank in a Gaussian vector autoregressive model. The usual asymptotic distribution typically gives rather large size distortions. This is explained by the fact that the asymptotic distribution of the likelihood ratio test statistic varies across the parameter space. A much improved distribution approximation can be obtained using local asymptotic theory. The idea is discussed for some low dimensional examples.  相似文献   
20.
Gerhard Lenski's ecological-evolutionary typology of human societies, based on the level of technology of a society and the nature of its physical environment, is a powerful predictor of various dimensions of social inequality. Analysis of comparative data shows that while some dimensions of the stratification system (such as measures of social complexity) exhibit a monotonic trend of increasing inequality with level of technology from the hunting-and-gathering to the agrarian type, others (such as measures of freedom and sexual inequality among males) exhibit a pattern of "agrarian reversal" in which inequality increases from the hunting‐and‐gathering to the advanced horticultural type but then declines with the agrarian type. Theoretical and empirical implications of the agrarian reversal pattern for the study of social inequality are discussed.  相似文献   
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