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To examine key parameters of the initial conditions in early category learning, two studies compared 5‐month‐olds’ object categorization between tasks involving previously unseen novel objects, and between measures within tasks. Infants in Experiment 1 participated in a visual familiarization–novelty preference (VFNP) task with two‐dimensional (2D) stimulus images. Infants provided no evidence of categorization by either their looking or their examining even though infants in previous research systematically categorized the same objects by examining when they could handle them directly. Infants in Experiment 2 participated in a VFNP task with 3D stimulus objects that allowed visual examination of objects’ 3D instantiation while denying manual contact with the objects. Under these conditions, infants demonstrated categorization by examining but not by looking. Focused examination appears to be a key component of young infants’ ability to form category representations of novel objects, and 3D instantiation appears to better engage such examining.  相似文献   
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Languages employ different strategies to mark an utterance as a polar (yes–no) question, including syntax, intonation and gestures. This study analyzes the production and perception of information-seeking questions and broad focus statements in Dutch and Catalan. These languages use intonation for marking questionhood, but Dutch also exploits syntactic variation for this purpose. A production task revealed the expected language-specific auditory differences, but also showed that gaze and eyebrow-raising are used in this distinction. A follow-up perception experiment revealed that perceivers relied greatly on auditory information in determining whether an utterance is a question or a statement, but accuracy was further enhanced when visual information was added. Finally, the study demonstrates that the concentration of several response-mobilizing cues in a sentence is positively correlated with the perceivers’ ratings of these utterances as interrogatives.  相似文献   
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This paper is a longitudinal analysis of the impacts of spontaneous volunteerism on those who responded to emergency needs immediately following the September 11, 2001 terrorist attacks on the World Trade Center in New York City. Our qualitative study investigates the long-term implications for the volunteers who participated in a myriad of helping behaviors ranging from working on the bucket brigade to serving food to rescue workers to working as translators for victims’ families. This project consists of two waves of data collection. The first set of in-depth interviews with 23 volunteers was conducted in the weeks following the attacks in the fall of 2001. In the second wave of interviews over 3 years later, we interviewed 20 volunteers, nearly half of whom were original respondents in the first wave. Through our analysis, we found that taking action facilitated meaningful therapeutic recovery from feelings of victimization following the event. In addition to the apparent long-term impact on personal healing, the opportunity to volunteer had lasting impacts on self-concept that translated to significant changes in life choices. The second wave of research also reveals that the experience of action impacted the volunteers’ community sentiment by fostering new levels of identification with and affinity for members of their community. In addition, community response work in the aftermath of a disaster appeared to increase community engagement in non-disaster times.  相似文献   
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The relative influence of perceived familial addictive behaviors and personal gambling behaviors on adolescents' self-perceptions of gambling problems was examined. Students from five high schools in Connecticut (N = 3,886) were surveyed. Of those between the ages of 14 and 17 who scored two or more on the South Oaks Gambling Screen--Revised for Adolescents (n = 532; 72% male; 43% Caucasian), 14.3% reported having a current or past problem with gambling. Wagering larger amounts in a single day, gambling on a daily basis, and perceived presence of a family member with a gambling problem were associated with increased odds of self-perception of a gambling problem. Thus, adolescents who may be less likely to be identified for prevention efforts (due to lack of engagement in high stakes gambling or the real/perceived absence of a problematic gambler in the home) appear less likely to perceive a gambling problem. To advance prevention and treatment strategies, the apparent discrepancy between adolescents' self-perceptions and objective reports of problem gambling behaviors warrants further investigation.  相似文献   
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This paper analyzes the cost increases due to demand uncertainty in single-level MRP lot sizing on a rolling horizon. It is shown that forecast errors have a tremendous effect on the cost effectiveness of lot-sizing techniques even when these forecast errors are small. Moreover, the cost differences between different techniques become rather insignificant in the presence of forecast errors. Since most industrial firms face demand uncertainty to some extent, our findings may have important managerial implications. Various simulation experiments give insight into both the nature and the magnitude of the cost increases for different heuristics. Analytical results are developed for the constant-demand case with random noise and forecasting by exponential smoothing. It is also shown how optimal buffers can be obtained by use of a simple model. Although the analysis in this paper is restricted to simplified cases, the results merit further consideration and study. This paper is one of the first to inject forecast errors into MRP lot-sizing research. As such it attempts to deal with one of the major objections against the practical relevance of previous research in this area.  相似文献   
27.
Many records in environmental sciences exhibit asymmetric trajectories. The physical mechanisms behind these records may lead for example to sample paths with different characteristics at high and low levels (up–down asymmetries) or in the ascending and descending phases leading to time irreversibility (front–back asymmetries). Such features are important for many applications, and there is a need for simple and tractable models that can reproduce them. In this paper, we explore original time‐change models where the clock is a stochastic process that depends on the observed trajectory. The ergodicity of the proposed model is established under general conditions, and this result is used to develop nonparametric estimation procedures based on the joint distribution of the process and its derivative. The methodology is illustrated on meteorological and oceanographic data sets. We show that, combined with a marginal transformation, the proposed methodology is able to reproduce important characteristics of the data set such as marginal distributions, up‐crossing intensity, and up–down and front–back asymmetries.  相似文献   
28.
Semi-structured interviews were used to explore identity development for nine adoptees (aged 9–23 years) who were adopted by their foster carers in New South Wales, Australia. Adoptions were open, with court-ordered face-to-face contact with birth families. Findings suggest that participants had healthy adoptive identities, with coherent and meaningful narratives about their life histories. Adoption provided a sense of security and belonging. Openness provided information to build a self-narrative and encouraged discussion of adoption issues within adoptive families. Adoptive parents were critical in helping children understand their adoption and facilitating direct contact with birth families, thus laying foundations for positive identity development.  相似文献   
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Emotional relationships in infant–mother dyads in families where mothers provided full‐time childcare were compared with those of families where mothers used in‐home childcare providers and family childcare providers (= 245). Infant relationships with childcare providers were also studied. Emotional relationships were adequate in all three childcare arrangements, but infant–mother dyads in in‐home childcare arrangements displayed healthier emotional relationships than infant–mother dyads in mother care arrangements; no differences in the health of emotional relationships with infants emerged among the three types of childcare providers (mother care, in‐home childcare, family childcare). Infant–mother dyads in in‐home childcare arrangements also displayed healthier emotional relationships than infant–in‐home childcare caregiver dyads, but infant–mother and infant–caregiver dyads were comparable in family childcare families. Emotional relationships in infant–mother and infant–caregiver dyads were not correlated, regardless of the type of childcare.  相似文献   
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