Jacky Chow

How many words is a bilingual 2-year-old supposed to know or say in each of her languages? Speech and language therapists or researchers lack the tools to answer this question, because several factors have an impact on bilingual language skills: gender, amount of exposure, mode of acquisition, socio-economic status and the distance between L1 and L2. Unfortunately, these factors are usually studied separately, making it difficult to evaluate their weight on a unique measure of vocabulary. The present study measures the contribution of the following factors to the vocabulary scores of bilingual toddlers: i) gender; ii) sibling ranking; iii) relative amount of exposure to each language; iv) mode of exposure; v) SES; vi) linguistic distance; vii) language spoken between parents. Close to the child’s second birthday, parents of 278 UK-based bilinguals completed successively: a 100-word version of the Oxford-CDI, the CDI in the child’s Additional Language, a family questionnaire, and the Language Exposure Questionnaire. Thirty-six British-English-AL pairs were considered, with languages contrasted on a second-language-learning scale : for example, Dutch and French are close to British-English, while Polish or Cantonese are more distant. Data from the corpus were included in two mixed-effect models, one with the English scores in comprehension as the dependent variable, and the other with production scores. The seven factors listed above were included as predictors. The amount of English exposure was the strongest predictor of comprehension scores = 9.35, p

Because of increased interest in the marine and atmospheric sciences in elemental carbon, or black carbon or soot carbon, and because of the difficulties in analyzing or even defining this pervasive component of particulate carbon, it has become quite important to have appropriate reference materials for intercomparison and quality control. The NIST "urban dust" Standard Reference Material® SRM 1649a is useful in this respect, in part because it comprises a considerable array of inorganic and organic species, and because it exhibits a large degree of isotopic heterogeneity, with biomass carbon source contributions ranging from about 2 % to about 32 %. A primary purpose of this report is to provide documentation for the new isotopic and chemical particulate carbon data for the most recent SRM 1649a Certificate of Analysis. Supporting this is a critical review of underlying international intercomparison data and methodologies, provided by 18 teams of analytical experts from 11 institutions. Key results of the intercomparison are: a new, Certified Value for total carbon in SRM 1649a; 14C Reference Values for total carbon and a number of organic species, including for the first time 8 individual PAHs; and elemental carbon Information Values derived from 13 analytical methods applied to this component. Results for elemental carbon, which comprised a special focus of the intercomparison, were quite diverse, reflecting the confounding of methodological-matrix artifacts, and methods that tended to probe more or less refractory regions of this universal, but ill-defined product of incomplete combustion. Availability of both chemical and 14C speciation data for SRM 1649a holds great promise for improved analytical insight through comparative analysis, and through application of the principle of isotopic mass balance.