L2 sentence processing strategies of late learners and heritage speakers: The Evidence from Mandarin-English Bilinguals

This study investigates different processing strategies of L1 Mandarin speakers processing complex sentences in L2 English. Heritage speakers, L2 learners, and native English speakers as a control group were compared. This study tested the Shallow Structure Hypothesis (SSH) which argues that second language processing differs from first language processing. Age of acquisition (AoA) and L2 dominance were factored in to determine the difference between L2 learners and heritage speakers. In an online grammatical-Maze experiment, 72 participants completed a processing task on three sentential items: relative clause modifying subject (RCS), relative clause modifying object (RCO), and adverb phrase modifying predicate (ADVP). The results show that with an early AoA and using L2 English dominantly, heritage speakers show native speaker-like processing patterns. While late L2 learners have an opposite pattern of processing RCS and RCO items, they show a native speaker-like pattern on the ADVP item. This suggests that AoA is a critical predictor of processing relative clause attachment but not for ADVP attachment. L2 dominance does not predict attachment preference on the RCS and ADVP items in the statistical results. However, it predicts that bilingual participants process RCO sentences comparable to native speakers. Based on the SSH, these predictions from AoA and L2 dominance are to be attributed to different weightings of the two pathways (i.e., syntactic and heuristic) in the sentence parser of L2 learners. When parsing complex sentences, the weightings of both the syntactic and heuristic pathways are not only affected by AoA but also significantly affected by L2 dominance. Also, different syntactic structures of processing are likely taking variant effects from AoA and L2 dominance. Overall, this study provides evidence of AoA and L2 dominance critically affecting L2 processing which needs to be taken into account as part of the SSH

A higher order numerical method for time fractional partial differential equations with nonsmooth data

Gao et al. (2014) introduced a numerical scheme to approximate the Caputo fractional derivative with the convergence rate $O(k^{3-\alpha}), 00$ for smooth and nonsmooth data in both homogeneous and inhomogeneous cases. Numerical examples are given to show that the theoretical results are consistent with the numerical results

Numerical Optimisation of a Classical Stochastic System for Targeted Energy Transfer

The paper studies stochastic dynamics of a two-degree-of-freedom system, where a primary linear system is connected to a nonlinear energy sink with cubic stiffness nonlinearity and viscous damping. While the primary mass is subjected to a zero-mean Gaussian white noise excitation, the main objective of this study is to maximise the efficiency of the targeted energy transfer in the system. A surrogate optimisation algorithm is proposed for this purpose and adopted for the stochastic framework. The optimisations are conducted separately for the nonlinear stiffness coefficient alone as well as for both the nonlinear stiffness and damping coefficients together. Three different optimisation cost functions, based on either energy of the system’s components or the dissipated energy, are considered. The results demonstrate some clear trends in values of the nonlinear energy sink coefficients and show the effect of different cost functions on the optimal values of the nonlinear system’s coefficients.publishedVersio

Solid-surface vitrification is an appropriate and convenient method for cryopreservation of isolated rat follicles

<p>Abstract</p> <p>Background</p> <p>Cryopreservation of isolated follicles may be a potential option to restore fertility in young women with cancer, because it can prevent the risks of cancer transmission. Several freezing protocols are available, including slow-rate freezing, open-pulled straws vitrification (OPS) and solid-surface vitrification (SSV, a new freezing technique). The purpose of our study was to investigate the effects of these freezing procedures on viability, ultrastructure and developmental capacity of isolated rat follicles.</p> <p>Methods</p> <p>Isolated follicles from female Sprague-Dawley rats were randomly assigned to SSV, OPS and slow-rate freezing groups for cryopreservation. Follicle viability assessment and ultrastructural examination were performed after thawing. In order to study the developmental capacity of thawed follicles, we performed <it>in vitro </it>culture with a three-dimensional (3D) system by alginate hydrogels.</p> <p>Results</p> <p>Our results showed that the totally viable rate of follicles vitrified by SSV (64.76%) was slightly higher than that of the OPS group (62.38%) and significantly higher than that of the slow-rate freezing group (52.65%; <it>P </it>< 0.05). The ultrastructural examination revealed that morphological alterations were relatively low in the SSV group compared to the OPS and slow-rate freezing groups. After <it>in vitro </it>culture within a 3D system using alginate hydrogels, we found the highest increase (28.90 ± 2.21 μm) in follicle diameter in follicles from the SSV group. The estradiol level in the SSV group was significantly higher than those in the OPS and slow-rate freezing groups at the end of a 72-hr culture period (<it>P </it>< 0.05).</p> <p>Conclusions</p> <p>Our results suggest that the SSV method is an appropriate and convenient method for cryopreservation of isolated rat follicles compared with the conventional slow-rate freezing method and the OPS method.</p

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals &lt;1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Dynamic compressive behavior of recycled aggregate concrete based on split Hopkinson pressure bar tests

This paper presents the experimental results of recycled aggregate concrete (RAC) specimens prepared with five different amount of recycled coarse aggregate (RCA) [i.e. 0, 25%, 50%, 75% and 100%] subjected to compressive loading based on split Hopkinson pressure bar tests. Strain-rate effects on dynamic compressive strength and critical strain of recycled aggregate concrete were studied. Results show that impact properties of recycled aggregate concrete exhibit strong strain-rate dependency, and increase approximately linearly with strain-rate. The transition point from low strain-rate sensitivity to high sensitivity decreases with the increase of matrix strength

Further Investigation on the Real Rate Effect of Dynamic Tensile Strength for Concrete-Like Materials

Abstract Based on dynamic direct tensile tests, splitting tests and spalling tests, it is found that the experimental tensile strength of concrete-like materials greatly increases with loading-rate. This kind of dynamic tensile strength enhancement may be caused by the combination influence of the inertia effect, real rate effect and end friction effect (here the end friction effect is only existed in splitting and spalling tests). To further investigate the influence degree of real rate effect for concrete-like materials in dynamic tensile tests, this paper conducts systematically dynamic tensile experiments, viz. dynamic direct tensile tests, splitting tests and spalling tests. At the same time, numerical dynamic tensile tests are employed to analyze the mechanical characteristics of concrete-like materials. A hydrostatic pressure dependent model, the Drucker-Prager constitutive model, is used for concrete-like material specimens, which can consider the influence of inertia effect. In the numerical model, the specimen is set to be rate-independent, thus the predicted dynamic tensile strength of specimens is free of the real rate effect. The end friction effect is also taken into account in the numerical analysis of dynamic splitting and spalling tests. It is found that the dynamic tensile strength of concrete-like materials in numerical simulations does not varies obviously with the loading-rate, indicating that the inertia effect and end friction effect have little contributions to the dynamic tensile strength enhancement of concrete-like materials. Therefore, the real rate effect dominates the dynamic tensile strength enhancement of concrete-like materials in laboratory tests, but the inertia effect and end friction effect do not

Numerical optimisation of a classical stochastic system for targeted energy transfer

The paper studies stochastic dynamics of a two-degree-of-freedom system, where a primary linear system is connected to a nonlinear energy sink with cubic stiffness nonlinearity and viscous damping. While the primary mass is subjected to a zero-mean Gaussian white noise excitation, the main objective of this study is to maximise the efficiency of the targeted energy transfer in the system. A surrogate optimisation algorithm is proposed for this purpose and adopted for the stochastic framework. The optimisations are conducted separately for the nonlinear stiffness coefficient alone as well as for both the nonlinear stiffness and damping coefficients together. Three different optimisation cost functions, based on either energy of the system’s components or the dissipated energy, are considered. The results demonstrate some clear trends in values of the nonlinear energy sink coefficients and show the effect of different cost functions on the optimal values of the nonlinear system’s coefficients