Evolution and distribution of medullary bone: evidence from a new Early Cretaceous enantiornithine bird

Living birds are unique among vertebrates in the formation of a female-specific bone tissue called medullary bone (MB) that is strictly associated with reproductive activity. MB is a rapidly mobilized source of calcium and phosphorus for the production of eggshell. Among living taxa, its skeletal distribution can be highly extensive such that it even exists in the ribs of some species. Due to its ephemeral nature, MB is rarely fossilized and so little is understood with regard to the origin of MB and its skeletal distribution in early taxa. Here we describe a new Early Cretaceous enantiornithine bird, Mirusavis parvus, gen. et. sp. nov., indicating that skeleton-wide distribution of MB appeared early in avian evolution. We suggest that this represents the plesiomorphic condition for the Aves and that the distribution of MB observed among extant neornithines is a product of increased pneumatization in this lineage and natural selection for more efficient distribution of MB.     

Learning in multiple contexts: are there intra-, cross- and transcontextual effects on the learner’s motivation and help seeking?

In Germany, Austria and Switzerland, the majority of 15?C19-year olds follow vocational education programmes within a dual-track system, spending most of their time in a company and going to school only 1?day each week. With their separate aims, content and sociological organisation, the company and the school can be considered as two distinct contexts within which apprentices have to acquire the various skills and competencies of their future occupation. In this paper, the development of apprentices?? learning intentions and motivation to learn, subjective competence, perceived utility of what is learned and estimated learning place attractiveness (study 1) as well as their readiness to seek help in these different contexts over the year of training (study 2) is analysed using both longitudinal and cross-sectional data. The findings show significant differences in apprentices?? motivation, their beliefs and their readiness to seek help in the different contexts throughout the training. Moderate (cross-different contexts, same time) as well as transcontextual (different contexts, different times) influences can also be seen. These results emphasise the importance of a careful delimitation of contexts when studying the impact of contextual factors on learners?? motivation and behaviours; they also suggest that motivation within one of these contexts can indirectly affect the learner??s motivation within another of these contexts. It is therefore likely that, by using these various dynamics appropriately, educators might temporarily sustain learners?? motivation in an unappreciated context by having recourse to a better accepted one.     

A preliminary study of student attitudes on juvenile justice policy

The philosophy and practice of juvenile justice have experienced significant transformations in the last 100 years. A shift to “get tough” attitudes has prompted various legislative reforms and has changed if not hardened attitudes toward youth. In context of these policy developments and social attitudes, this paper summarizes a preliminary study of 1104 undergraduate students on their attitudes on juvenile justice policies in the United States. Student perceptions of school violence, and attitudes toward zero tolerance and drug testing are reported. The authors discuss the responses of criminal justice majors and consider the implications of their academic experience on knowledge and attitudes about juvenile justice.     

General auditory processing, Chinese tone processing, English phonemic processing and English reading skill: a comparison between Chinese-English and Korean-English bilingual children

In the present study, we investigated the relationship between general auditory processing, Chinese tone processing, English phonemic processing and English reading skill in a group of Chinese-English bilingual children with a tonal L1 and Korean-English counterparts with a non-tonal L1. We found that general auditory processing contributed to variance in English word reading skill for Chinese children after controlling for Chinese tone and English phoneme deletion skill. English phonemic processing, on the other hand, explained a significant amount of unique variance in English reading for Korean children after controlling for general auditory and Chinese tone skill. These findings suggest that Chinese children relied more on general auditory processing in reading English, whereas Korean children relied more on phonemic skill in reading English. These findings are discussed in terms of the impact of cross-language differences in bilingual reading acquisition.     

The utility of Chinese tone processing skill in detecting children with English reading disabilities

The utility of Chinese tone processing skill in detecting children with English reading difficulties was examined through differences in a Chinese tone experimental task between a group of native English‐speaking children with reading disabilities (RD) and a comparison group of children with normal reading development (NRD). General auditory processing, English phonemic processing and English reading skills were also tested. We found differences between groups in Chinese tone processing skill, as well as general auditory processing and English phonemic skills. The RD group was significantly poorer than NRD on tasks of Chinese tone, phonemic and frequency modulated (FM) tone processing. Another finding was a different pattern of relationship between RD and NRD groups in Chinese tone, phonemic and FM tone processing as predictors of reading skills. For children with RD, FM tone processing was a significant predictor of pseudoword reading; for NRD, phonemic and Chinese tone processing skills predicted real word reading. These findings contribute to improved understanding of the roles of general auditory processing and phonological processing skills in RD, with implications for assessment and intervention with children who have English reading difficulties.     

Evidence of proteins,chromosomes and chemical markers of DNA in exceptionally preserved dinosaur cartilage

A histological ground-section from a duck-billed dinosaur nestling (Hypacrosaurus stebingeri) revealed microstructures morphologically consistent with nuclei and chromosomes in cells within calcified cartilage. We hypothesized that this exceptional cellular preservation extended to the molecular level and had molecular features in common with extant avian cartilage. Histochemical and immunological evidence supports in situ preservation of extracellular matrix components found in extant cartilage, including glycosaminoglycans and collagen type II. Furthermore, isolated Hypacrosaurus chondrocytes react positively with two DNA intercalating stains. Specific DNA staining is only observed inside the isolated cells, suggesting endogenous nuclear material survived fossilization. Our data support the hypothesis that calcified cartilage is preserved at the molecular level in this Mesozoic material, and suggest that remnants of once-living chondrocytes, including their DNA, may preserve for millions of years.