Affiliative Subgroups in Preschool Classrooms: Integrating Constructs and Methods from Social Ethology and Sociometric Traditions

Recent studies of school-age children and adolescents have used social network analyses to characterize selection and socialization aspects of peer groups. Fewer network studies have been reported for preschool classrooms and many of those have focused on structural descriptions of peer networks, and/or, on selection processes rather than on social functions of subgroup membership. In this study we started by identifying and describing different types of affiliative subgroups (HMP- high mutual proximity, LMP- low mutual proximity, and ungrouped children) in a sample of 240 Portuguese preschool children using nearest neighbor observations. Next, we used additional behavioral observations and sociometric data to show that HMP and LMP subgroups are functionally distinct: HMP subgroups appear to reflect friendship relations, whereas LMP subgroups appear to reflect common social goals, but without strong, within-subgroup dyadic ties. Finally, we examined the longitudinal implications of subgroup membership and show that children classified as HMP in consecutive years had more reciprocated friendships than did children whose subgroup classification changed from LMP or ungrouped to HMP. These results extend previous findings reported for North American peer groups

Affiliative Subgroups in Preschool Classrooms: Integrating Constructs and Methods from Social Ethology and Sociometric Traditions

Recent studies of school-age children and adolescents have used social network analyses to characterize selection and socialization aspects of peer groups. Fewer network studies have been reported for preschool classrooms and many of those have focused on structural descriptions of peer networks, and/or, on selection processes rather than on social functions of subgroup membership. In this study we started by identifying and describing different types of affiliative subgroups (HMP- high mutual proximity, LMP- low mutual proximity, and ungrouped children) in a sample of 240 Portuguese preschool children using nearest neighbor observations. Next, we used additional behavioral observations and sociometric data to show that HMP and LMP subgroups are functionally distinct: HMP subgroups appear to reflect friendship relations, whereas LMP subgroups appear to reflect common social goals, but without strong, within-subgroup dyadic ties. Finally, we examined the longitudinal implications of subgroup membership and show that children classified as HMP in consecutive years had more reciprocated friendships than did children whose subgroup classification changed from LMP or ungrouped to HMP. These results extend previous findings reported for North American peer groups

Métodos de observação e análise para identificação das estruturas afiliativas de grupos de crianças em meio pré-escolar

Os modelos etológicos em desenvolvimento social sublinham que os grupos naturais proporcionam uma variedade de contextos sociais que influenciam de forma diferencial o crescimento e desenvolvimento individual. Contudo, os estudos comportamentais de primatas humanos e não-humanos têm sobretudo incidido nas relações de agressividade e estruturas de dominância. A investigação da organização do comportamento afiliativo tem sido impedida devido à falta de modelos e métodos para o estudo das estruturas sociais coesivas. As análises de agrupamento e redes sociais dos padrões de associação entre pares fornecem uma base alternativa para investigar a organização social de grupos infantis estáveis e para avaliar como é que os tipos afiliativos no interior do grupo podem influenciar o desenvolvimento individual. Os resultados do presente estudo contribuem directamente para a operacionalização de tais modelos descritivos das estruturas coesivas dos grupos de pares. A discussão dos resultados centra-se na forma como a inserção da criança na estrutura afiliativa do grupo de pares constrange o seu comportamento social e proporciona experiências específicas que servem como contextos para a construção de relações interpessoais mais íntimas

Métodos de observação e análise para identificação das estruturas afiliativas de grupos de crianças em meio pré-escolar

Os modelos etológicos em desenvolvimento social sublinham que os grupos naturais proporcionam uma variedade de contextos sociais que influenciam de forma diferencial o crescimento e desenvolvimento individual. Contudo, os estudos comportamentais de primatas humanos e não-humanos têm sobretudo incidido nas relações de agressividade e estruturas de dominância. A investigação da organização do comportamento afiliativo tem sido impedida devido à falta de modelos e métodos para o estudo das estruturas sociais coesivas. As análises de agrupamento e redes sociais dos padrões de associação entre pares fornecem uma base alternativa para investigar a organização social de grupos infantis estáveis e para avaliar como é que os tipos afiliativos no interior do grupo podem influenciar o desenvolvimento individual. Os resultados do presente estudo contribuem directamente para a operacionalização de tais modelos descritivos das estruturas coesivas dos grupos de pares. A discussão dos resultados centra-se na forma como a inserção da criança na estrutura afiliativa do grupo de pares constrange o seu comportamento social e proporciona experiências específicas que servem como contextos para a construção de relações interpessoais mais íntimas

Crystal Structure of the Hemochromatosis Protein HFE and Characterization of Its Interaction with Transferrin Receptor

AbstractHFE is an MHC-related protein that is mutated in the iron-overload disease hereditary hemochromatosis. HFE binds to transferrin receptor (TfR) and reduces its affinity for iron-loaded transferrin, implicating HFE in iron metabolism. The 2.6 Å crystal structure of HFE reveals the locations of hemochromatosis mutations and a patch of histidines that could be involved in pH-dependent interactions. We also demonstrate that soluble TfR and HFE bind tightly at the basic pH of the cell surface, but not at the acidic pH of intracellular vesicles. TfR:HFE stoichiometry (2:1) differs from TfR:transferrin stoichiometry (2:2), implying a different mode of binding for HFE and transferrin to TfR, consistent with our demonstration that HFE, transferrin, and TfR form a ternary complex

Co-evolution of friendships and antipathies: A longitudinal study of preschool peer groups

Material suplementar está disponível em: http://journal.frontiersin.org/article/10.3389/fpsyg. 2016.01509This Document is Protected by copyright and was first published by Frontiers. All rights reserved. It is reproduced with permission.We used stochastic actor-based models to test whether the developmental dynamics of friendships and antipathies in preschool peer groups (followed throughout three school years) were co-dependent. We combined choices from three sociometric tasks of 142 children to identify friendship and antipathy ties and used SIENA to model network dynamics. Our results show that different social processes drive the development of friendship and antipathy ties, and that they do not develop in association (i.e., friendship ties are not dependent on existing antipathies, and vice-versa). These results differ from those of older children (age range = 10-14) suggesting that the interplay of friendship and antipathy only plays a significant role in the peer group context in older children. We propose these differences to be likely related with preschool age children's inaccurate perceptions of their classmates' relationships, particularly of their antipathies, and/or with the absence of shared norms to deal with antipathetic relationships.Fundação para a Ciência e a Tecnologia (FCT); National Science Foundation (NSF

Social competence in preschool children: Replication of results and clarification of a hierarchical measurement model

This study tested assumptions and conclusions reached in an earlier confirmatory factor analysis (CFA) study of the social competence (SC) construct for preschool children. Two samples (total N = 408; a new Portuguese sample and one from US samples that had participated in the original study) contributed data. Seven SC indicators were tested for mean differences across age, sex, and sample. Significant sex differences were found for peer acceptance (favoring girls) and for initiating affectively neutral interactions (boys had higher rates), and the sex by sample interaction also was significant for initiating interactions (i.e., effect significant only in the Portuguese sample). In CFAs, the hypothesized structure of SC fits the data and was invariant across sample and age within sample in both measurement and structural tests. The model was invariant at the measurement level for sex within sample tests, but not at the structural level. The results replicate and extend understandings of SC reported in the original study

Intrinsic ergodicity beyond specification: beta-shifts, S-gap shifts, and their factors

We give sufficient conditions for a shift space $(\Sigma,\sigma)$ to be intrinsically ergodic, along with sufficient conditions for every subshift factor of $\Sigma$ to be intrinsically ergodic. As an application, we show that every subshift factor of a $\beta$-shift is intrinsically ergodic, which answers an open question included in Mike Boyle's article "Open problems in symbolic dynamics". We obtain the same result for $S$-gap shifts, and describe an application of our conditions to more general coded systems. One novelty of our approach is the introduction of a new version of the specification property that is well adapted to the study of symbolic spaces with a non-uniform structure.Comment: 27 pages, 1 figure, minor changes based on referee's suggestions, in v.3 the result on coded systems has been moved to the introduction, resulting in small changes to numbering (lettering) of result

Gene disruption by structural mutations drives selection in US rice breeding over the last century.

The genetic basis of general plant vigor is of major interest to food producers, yet the trait is recalcitrant to genetic mapping because of the number of loci involved, their small effects, and linkage. Observations of heterosis in many crops suggests that recessive, malfunctioning versions of genes are a major cause of poor performance, yet we have little information on the mutational spectrum underlying these disruptions. To address this question, we generated a long-read assembly of a tropical japonica rice (Oryza sativa) variety, Carolina Gold, which allowed us to identify structural mutations (>50 bp) and orient them with respect to their ancestral state using the outgroup, Oryza glaberrima. Supporting prior work, we find substantial genome expansion in the sativa branch. While transposable elements (TEs) account for the largest share of size variation, the majority of events are not directly TE-mediated. Tandem duplications are the most common source of insertions and are highly enriched among 50-200bp mutations. To explore the relative impact of various mutational classes on crop fitness, we then track these structural events over the last century of US rice improvement using 101 resequenced varieties. Within this material, a pattern of temporary hybridization between medium and long-grain varieties was followed by recent divergence. During this long-term selection, structural mutations that impact gene exons have been removed at a greater rate than intronic indels and single-nucleotide mutations. These results support the use of ab initio estimates of mutational burden, based on structural data, as an orthogonal predictor in genomic selection