The Influence of Language-Specific and Universal Factors on Acquisition of Motion Verbs

This study explores children’s encoding of novel verbs referring to motion events, and finds influence of both language-specific and universal constraints on meaning. Motion verbs fall into two categories—manner verbs encode how a movement happens (run, swim), and path verbs encode the starting and ending point of a motion (enter, fall). Some languages express path more frequently in the verb (Spanish, Hebrew), and others manner more frequently (English, German). Our study expands on this previous work demonstrating sensitivity to these language-specific distributions, as well as expanding to test environmental factors representing a predictable universal distribution. We find that children are sensitive to both the language-specific factors as well as the universal factors in motion verb acquisition

Verbs of Motion: Effects of Cross-linguistic Transfer in Spanish-English Bilingual Children

Languages populate a typological spectrum between verb-framed and satellite-framed based on how they encode Path, the trajectory of a figure related to a fixed point, in motion events. Verb-framed languages encode Path on the main verb (e.g. enter, exit, cross). Satellite-framed languages tend to encode Path in a predicative satellite like a preposition, leaving the verb slot open for the optional element of Manner or how the figure moves (e.g. walk, jump). Bilingual speakers of one of each type, like of Spanish and English respectively, experience transfer between their two languages during acquisition. This study aims to integrate interaction between first languages and typological theory of verb frames in order to determine if bilingualism produces facilitatory effects in Path verb learning in Spanish-English bilingual children. Participants were 33 preschool and elementary school students (MAGE 5.02) who were recruited based on their language status. Monolingual English speaking and Spanish-English bilingual children participated in a forced choice task and were scored on their ability to correctly identify novel verbs as Path or Manner. Results produced a significant main effect for the verb type conditions, and a significant interaction between language group conditions and verb type conditions. However, contrary to the hypothesis, bilinguals showed decelerated accuracy in the Path condition. More participants must be run, and more variations of this study must be conducted in order to determine the cause of these effects

Charge-tunnelling and self-trapping: common origins for blinking, grey-state emission and photoluminescence enhancement in semiconductor quantum dots

Understanding instabilities in the photoluminescence (PL) from light emitting materials is crucial to optimizing their performance for different applications. Semiconductor quantum dots (QDs) offer bright, size tunable emission, properties that are now being exploited in a broad range of developing technologies from displays and solar cells to biomaging and optical storage. However, instabilities such as photoluminescence intermittency, enhancement and bleaching of emission in these materials can be detrimental to their utility. Here, we report dielectric dependent blinking, intensity-“spikes” and low-level, “grey”-state emission, as well as PL enhancement in ZnS capped CdSe QDs; observations that we found consistent with a charge-tunnelling and self-trapping (CTST) description of exciton-dynamics on the QD–host system. In particular, modulation of PL in grey-states and PL enhancement are found to have a common origin in the equilibrium between exciton charge carrier core and surface-states within the CTST framework. Parameterized in terms of size and electrostatic properties of the QD and its nanoenvironment, the CTST offers predictive insight into exciton-dynamics in these nanomaterials

Bright Fraction of Single-Walled Carbon Nanotubes through Correlated Fluorescence and Topography Measurements

Correlated measurements of fluorescence and topography were performed for individual single-walled carbon nanotubes (SWNTs) on quartz using epifluorescence confocal microscopy and atomic force microscopy (AFM). Surprisingly, only ∼11% of all SWNTs in DNA-wrapped samples were found to be highly emissive on quartz, suggesting that the ensemble fluorescence quantum yield is low because only a small population of SWNTs fluoresces strongly. Qualitatively similar conclusions were obtained from control studies using a sodium cholate surfactant system. To accommodate AFM measurements, excess surfactant was removed from the substrate. Though individual SWNTs on nonrinsed and rinsed surfaces displayed differences in fluorescence intensities and line widths, arising from the influence of the local environment on individual SWNT optical measurements, photoluminescence data from both samples displayed consistent trends