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Francesco?C.?BillariEmail author Letizia?Mencarini 《Statistical Methods and Applications》2004,12(3):377-390
We investigate the impact of some characteristics of friendship networks on the timing of the first sexual intercourse. We assume that the gender-segregated composition of such networks explains part of the particularly late age at first intercourse in Italy. We use new data from a survey on sexual behavior and reproductive health of Italian first and second-year university students. The survey has been carried out in 15 different universities in 2000-2001 and it includes retrospective data on age at first intercourse, as well as retrospectively-collected time-varying measures for the gender composition of the friendship network at different ages, for almost 5,000 cases. After having described the data as transition frequencies, we use a Cox proportional hazards model with time-varying covariates. Results are in accordance with the hypothesis that having friendship networks that include more members of the other gender and talking about sex with friends increases the relative risk of first sexual intercourse. 相似文献
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In a complex social environment, stimuli from different sensory modalities need to be integrated to decode communicative meanings. From very early in life, infants have to combine a multitude of sensory features with social and affective attributes. Of all senses, touch constitutes a privileged channel to carry affective-motivational meanings and foster social connection. In the present study, we investigate whether sharing sensory stimulation that varies for its affective value differentially affects infants' attention towards visual stimuli. 6 to 11-month-old infants (N = 42) were familiarized with two characters respectively matched with tactile (affective or non-affective) and auditory stimulation; then repeatedly exposed to scenes where the two characters moved towards target objects. Our results showed a main effect of stimulation (sound vs. touch) on looking times during familiarization, with longer looking times when sound is provided. During scenes presentation, a main effect of the type of touch (affective vs. non affective) emerged, with longer looking times in infants that previously experienced affective touch, suggesting that this sensory experience may critically engage the self and modulate infant attention. Overall, these findings suggest that while sound acts as attention getter, affective touch supports sustained attention towards complex visual scenes beyond the stimulation period itself. 相似文献
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ABSTRACT: The authors, in this article, consider the possibility of how the peak in the birth rate during the 60s could have affected the present unemployment situation. First of all the hypothesis put forward by various sources that the baby boom is the principle cause of unemployment is examined, together with how plausible this explanation is. Then some data relevant to birth rates and the subsequent employment levels in various countries is presented, and finally, a more detailed analysis of the Italian situation is given, both with regard to the baby boom and the most recent employment statistics for the different Italian areas. The authors also take a close look at the female labour market and its development over the past years, and how these figures would appear to confute the baby boom as being the sole cause responsible for present day unemployment levels. 相似文献