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The inverse design of meta-optics has received much attention in recent years. In this paper, we propose a GPU-friendly inverse design framework based on improved eigendecomposition-free rigorous diffraction interface theory, which offers up to 16.2 × speedup over the traditional inverse design based on rigorous coupled-wave analysis. We further improve the framework’s flexibility by introducing a hybrid parameterization combining neural-implicit and traditional shape optimization. We demonstrate the effectiveness of our framework through intricate tasks, including the inverse design of reconfigurable free-form meta-atoms.

 

Purpose: Stuttering-like disfluencies (SLDs) and typical disfluencies (TDs) are both more likely to occur as utterance length increases. However, longer and shorter utterances differ by more than the number of morphemes: They may also serve different communicative functions or describe different ideas. Decontextualized language, or language that describes events and concepts outside of the “here and now,” is associated with longer utterances. Prior work has shown that language samples taken in decontextualized contexts contain more disfluencies, but averaging across an entire language sample creates a confound between utterance length and decontextualization as contributors to stuttering. We coded individual utterances from naturalistic play samples to test the hypothesis that decontextualized language leads to increased disfluencies above and beyond the effects of utterance length. Method: We used archival transcripts of language samples from 15 preschool children who stutter (CWS) and 15 age- and sex-matched children who do not stutter (CWNS). Utterances were coded as either contextualized or decontextualized, and we used mixed-effects logistic regression to investigate the impact of utterance length and decontextualization on SLDs and TDs. Results: CWS were more likely to stutter when producing decontextualized utterances, even when controlling for utterance length. An interaction between decontextualization and utterance length indicated that the effect of decontextualization was greatest for shorter utterances. TDs increased in decontextualized utterances when controlling for utterance length for both CWS and CWNS. The effect of decontextualization on TDs did not differ statistically between the two groups. Conclusions: The increased working memory demands associated with decontextualized language contribute to increased language planning effort. This leads to increased TD in CWS and CWNS. Under a multifactorial dynamic model of stuttering, the increased language demands may also contribute to increased stuttering in CWS due to instabilities in their speech motor systems. 

Abstract Research has suggested that children who speak African American English (AAE) have difficulty using features produced in Mainstream American English (MAE) but not AAE, to comprehend sentences in MAE. However, past studies mainly examined dialect features, such as verbal -s , that are produced as final consonants with shorter durations when produced in conversation which impacts their phonetic saliency. Therefore, it is unclear if previous results are due to the phonetic saliency of the feature or how AAE speakers process MAE dialect features more generally. This study evaluated if there were group differences in how AAE- and MAE-speaking children used the auxiliary verbs was and were, a dialect feature with increased phonetic saliency but produced differently between the dialects, to interpret sentences in MAE. Participants aged 6, 5–10, and 0 years, who spoke MAE or AAE, completed the DELV-ST, a vocabulary measure (PVT), and a sentence comprehension task. In the sentence comprehension task, participants heard sentences in MAE that had either unambiguous or ambiguous subjects. Sentences with ambiguous subjects were used to evaluate group differences in sentence comprehension. AAE-speaking children were less likely than MAE-speaking children to use the auxiliary verbs was and were to interpret sentences in MAE. Furthermore, dialect density was predictive of Black participant’s sensitivity to the auxiliary verb. This finding is consistent with how the auxiliary verb is produced between the two dialects: was is used to mark both singular and plural subjects in AAE, while MAE uses was for singular and were for plural subjects. This study demonstrated that even when the dialect feature is more phonetically salient, differences between how verb morphology is produced in AAE and MAE impact how AAE-speaking children comprehend MAE sentences. 

Progress in hardware and algorithms for artificial intelligence (AI) has ushered in large machine learning models and various applications impacting our everyday lives. However, today's AI, mainly artificial neural networks, still cannot compete with human brains because of two major issues: the high energy consumption of the hardware running AI models and the lack of ability to generalize knowledge and self-adapt to changes. Neuromorphic systems built upon emerging devices, for instance, memristors, provide a promising path to address these issues. Although innovative memristor devices and circuit designs have been proposed for neuromorphic computing and applied to different proof-of-concept applications, there is still a long way to go to build large-scale low-power memristor-based neuromorphic systems that can bridge the gap between AI and biological brains. This Perspective summarizes the progress and challenges from memristor devices to neuromorphic systems and proposes possible directions for neuromorphic system implementation based on memristive devices. 

Bragg gratings offer high-performance filtering and routing of light on-chip through a periodic modulation of a waveguide’s effective refractive index. Here, we model and experimentally demonstrate the use of Sb₂Se₃, a nonvolatile and transparent phase-change material, to tune the resonance conditions in two devices which leverage periodic Bragg gratings—a stopband filter and Fabry-Perot cavity. Through simulations, we show that similar refractive indices between silicon and amorphous Sb₂Se₃can be used to induce broadband transparency, while the crystalline state can enhance the index contrast in these Bragg devices. Our experimental results show the promise and limitations of this design approach and highlight specific fabrication challenges which need to be addressed in future implementations.

 

Socioeconomic status (SES) differences in language development are ubiquitous, but existing research has yet to wrestle with how language gaps reflect ( a) differences in relevant concepts for communication, ( b) comprehension strategies to access meanings, and ( c) production practices that express social identity. In child-directed input, parents use verbs to describe similar concepts across SES, and the largest gaps emerge when frequent meanings are being conveyed. During comprehension, children acquire infrequent aspects of grammar across SES but differ in context-specific strategies for interpreting likely meanings. In production, children are sensitive to sociolinguistic implications and adopt context-specific strategies to signal social identity. This suggests that language is a flexible medium for communicating thoughts and that SES effects signal latent differences in meanings and identities across social classes. Whether language gaps contribute to achievement gaps may depend on the extent to which learning and communication draw on these meanings and value these identities. 

The nanoscopic deformation of ⟨111⟩ nanotwinned copper nanopillars under strain rates between 10^−5/s and 5×10^−4/s was studied by using in situ transmission electron microscopy. The correlation among dislocation activity, twin boundary instability due to incoherent twin boundary migration and corresponding mechanical responses was investigated. Dislocations piled up in the nanotwinned copper, giving rise to significant hardening at relatively high strain rates of 3–5×10^−4/s. Lower strain rates resulted in detwinning and reduced hardening, while corresponding deformation mechanisms are proposed based on experimental results. At low/ultralow strain rates below 6×10^−5/s, dislocation activity almost ceased operating, but the migration of twin boundaries via the 1/4 ⟨10-1⟩ kink-like motion of atoms is suggested as the detwinning mechanism. At medium strain rates of 1–2×10^−4/s, detwinning was decelerated likely due to the interfered kink-like motion of atoms by activated partial dislocations, while dislocation climb may alternatively dominate detwinning. These results indicate that, even for the same nanoscale twin boundary spacing, different nanomechanical deformation mechanisms can operate at different strain rates.