Recent conceptualisations of bilingualism are moving away from strict categorisations, towards continuous approaches. This study supports this trend by combining empirical psycholinguistics data with machine learning classification modelling. Support vector classifiers were trained on two datasets of coded productions by Italian speakers to predict the class they belonged to (“monolingual”, “attriters” and “heritage”). All classes can be predicted above chance (>33%), even if the classifier's performance substantially varies, with monolinguals identified much better (f-score >70%) than attriters (f-score <50%), which are instead the most confusable class. Further analyses of the classification errors expressed in the confusion matrices qualify that attriters are identified as heritage speakers nearly as often as they are correctly classified. Cluster clitics are the most identifying features for the classification performance. Overall, this study supports a conceptualisation of bilingualism as a continuum of linguistic behaviours rather than sets of a priori established classes.

Previous studies show that even though monolingual children find subject relatives easier than object relatives, their comprehension of object relatives can be facilitated by morphological cues. Given that in heritage contexts functional morphology is a vulnerable domain, a question that needs to be addressed is whether bilingual children, who are heritage speakers of their L1, will also be able to use morphological cues to comprehend complex syntax. To contribute to this line of research, we focused on monolingual (N = 18; Mean Age: 11.43) and bilingual/first generation (N = 108; Mean Age: 11.98), Syrian Arabic-speaking children in Canada, and examined their ability to use gender morphology in their comprehension of relative clauses, while taking into consideration cognitive, environmental, and age-related variables. To this end, we used two offline sentence-picture matching tasks targeting relative clauses and gender (as encoded in SV agreement and object clitics). Results showed that, like monolingual children, first-generation, Arabic-speaking children living in Canada used morphological cues to comprehend complex syntax in their L1. Furthermore, even though there was an association between comprehension of gender agreement and comprehension of relative clauses, performance in gender agreement was higher than performance in relative clauses, suggesting that challenges with complex syntactic structures are not necessarily an epiphenomenon of a morphological deficit.

Despite admonitions to address attrition in experiments – missingness on Y – alongside best practices designed to encourage transparency, most political science researchers all but ignore it. A quantitative literature search of this journal – where we would expect to find the most conscientious reporting of attrition – shows low rates of discussion of the issue. We suspect that there is confusion on the link between when attrition occurs and the type of validity it threatens when present, and limited connection to and guidance on which estimands are threatened by different attrition patterns. This is all exacerbated by limited tools to identify, investigate, and report patterns attrition. We offer the R package – attritevis – to visualize attrition over time, by intervention, and include a step-by-step guide to identifying and addressing attrition that balances post hoc analytical tools with guidance for revising designs to ameliorate problematic attrition.

The Oslo University Adolescent and Young Adult Twin Project started in 2006 with the first of three questionnaire data collection waves, 2 years apart. All twins from the birth cohorts 1988–1994 were invited to participate, and both the twins and their parents were asked to sign consent forms. The twins were 12–18 years old at Wave 1, at which time parents were asked to complete similar questionnaires. The parents’ questionnaire enquired about the parents’ ratings of their twin’s traits. In addition, the parents answered questions regarding their own education, demographics and socioeconomic situation. When the twins were 18 years old, they were invited to a face-to-face interview and two new questionnaires were presented. The questionnaires for the waves included a number of personality scales, internalization and externalization traits, affective and behavioral problems, as well as measures of environment and coping. The most common DSM-IV mental disorders and all personality disorders were covered in the interview. Zygosity was established both by questionnaire and gene markers. The original sample consisted of 5374 twin families, and among these, 4668 pairs were alive and living in Norway. Of these, 2486 families (53.3%) consented to participate. Of these, again 1538 twin families (61.9%) actually participated in at least one wave and twins from 1422 pairs (57.3%) participated in the interview. Female gender, but not zygosity, predicted staying in the project. Moreover, having a planning, structured personality (being more conscientious, open to experience [i.e., curious and interested in learning], having higher resilience and better school habits) increased the chance of carrying on in the project. Interestingly, the attrition did not seem to bias the heritability estimates.

With a growing interest in heritage languages from researchers of bilingualism and linguistic theory, the field of heritage-language studies has begun to build on its empirical foundations, moving toward a deeper understanding of the nature of language competence under unbalanced bilingualism. In furtherance of this trend, the current work synthesizes pertinent empirical observations and theoretical claims about vulnerable and robust areas of heritage language competence into early steps toward a model of heritage-language grammar. We highlight two key triggers for deviation from the relevant baseline: the quantity and quality of the input from which the heritage grammar is acquired, and the economy of online resources when operating in a less dominant language. In response to these triggers, we identify three outcomes of deviation in the heritage grammar: an avoidance of ambiguity, a resistance to irregularity, and a shrinking of structure. While we are still a ways away from a level of understanding that allows us to predict those aspects of heritage grammar that will be robust and those that will deviate from the relevant baselines, our hope is that the current work will spur the continued development of a predictive model of heritage language competence.

This study investigates possessives and modified definite DPs in a corpus of heritage Norwegian spoken in the US. Both constructions involve variation in Norwegian – two word orders for possessives (pre- and postnominal) and two exponents of definiteness (a prenominal determiner and a suffix) – while English only has one of these options. The findings show that a large majority of the heritage speakers overuse the structures that are maximally different from English structures, i.e., postnominal possessors and single suffixal definiteness marking. We argue that their production pattern is the result of cross-linguistic overcorrection (CLO). In addition, a small group of the heritage speakers show signs of cross-linguistic influence (CLI) and overuse the English-like structures in both constructions. These speakers also have a slightly lower proficiency in the heritage language. Our findings are discussed in terms of previous research on monolingual and Norwegian–English bilingual children.

The surfacing welding has been widely utilized in the industrial equipment manufacturing and repairs. The wear properties of surfacing alloys have an important effect on the whole performance of repaired components. The solution treatment (T4) and solution treatment followed by aging (T6) effects on the dry sliding wear behavior of surfacing AZ91 magnesium alloys with tungsten inert gas welding were investigated in this work. The results demonstrated that the surfacing alloy without treatment exhibited poor wear resistance, due to the massive intermetallic β-phases (Mg17Al12). These phases were believed to produce stress concentrations in the particle-to-matrix interface and tended to generate cracks during friction. The T4 alloy had more improved wear resistance than the as-received alloy. The T6 treatment improved the wear resistance further, resulting from the high density dispersed fine β-phase precipitation in the α-Mg matrix, which enhanced the alloy strength and hardness and decreased the subsurface metal deformation degree caused by friction.