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10. The Influence of Partners' L2 Proficiency on Test-Takers' Performance in Paired Oral Assessment

Author

Chen, Jiliang, Li, Lanlan, Shen, Yalin, and Li, Haoxia

Abstract

This study is intended to explore the influence of partners' L2 proficiency on test-takers' performance and on their interaction patterns in paired oral assessment, and it tries to analyze the underlying causes on the basis of Vygotsky's theory of the zone of proximal development (ZPD) and Storch's patterns of interaction. An experiment including three rounds of tests was carried out with 12 students who were selected out of 60 from a top university in China. The findings showed that the high-level test-takers received the highest scores when paired with middle-level partners; the middle-level test-takers scored the highest and the lowest when paired with high-level partners and low-level partners respectively; the low-level test-takers had basically the same scores when paired with those of the other two different levels. The results could be partly explained by the fact that the higher level partners stimulated the lower level test-takers to the upper limit of ZPD through language interaction, but the mechanism of ZPD might not work when partners' proficiency levels were much higher than the ceiling of test-takers' ZPD. Besides, test-takers' performance was mediated by pair interaction patterns. The implications of the study not only deliver suggestions for fairness of paired oral assessment but also provide alternatives for test-takers to achieve higher scores in a paired speaking test by choosing partners of different L2 proficiency levels.

Published
2022

13. Glucose metabolism patterns: A potential index to characterize brain ageing and predict high conversion risk into cognitive impairment

Author

Jiang, Jiehui, Sheng, Can, Chen, Guanqun, Liu, Chunhua, Jin, Shichen, Li, Lanlan, Jiang, Xueyan, and Han, Ying

Subjects
Biological Sciences, Biomedical and Clinical Sciences, Clinical Sciences, Genetics, Biomedical Imaging, Dementia, Neurodegenerative, Neurosciences, Aging, Prevention, Clinical Research, Alzheimer's Disease, Brain Disorders, Acquired Cognitive Impairment, Alzheimer's Disease including Alzheimer's Disease Related Dementias (AD/ADRD), Neurological, Mental health, Humans, Aged, Alzheimer Disease, Positron-Emission Tomography, Cognitive Dysfunction, Fluorodeoxyglucose F18, Brain, Glucose, Pattern, Brain ageing, Positron emission tomography, Glucose metabolism, Alzheimer’s Disease Neuroimaging Initiative, Clinical sciences
Abstract

Exploring individual hallmarks of brain ageing is important. Here, we propose the age-related glucose metabolism pattern (ARGMP) as a potential index to characterize brain ageing in cognitively normal (CN) elderly people. We collected 18F-fluorodeoxyglucose (18F-FDG) PET brain images from two independent cohorts: the Alzheimer's Disease Neuroimaging Initiative (ADNI, N = 127) and the Xuanwu Hospital of Capital Medical University, Beijing, China (N = 84). During follow-up (mean 80.60 months), 23 participants in the ADNI cohort converted to cognitive impairment. ARGMPs were identified using the scaled subprofile model/principal component analysis method, and cross-validations were conducted in both independent cohorts. A survival analysis was further conducted to calculate the predictive effect of conversion risk by using ARGMPs. The results showed that ARGMPs were characterized by hypometabolism with increasing age primarily in the bilateral medial superior frontal gyrus, anterior cingulate and paracingulate gyri, caudate nucleus, and left supplementary motor area and hypermetabolism in part of the left inferior cerebellum. The expression network scores of ARGMPs were significantly associated with chronological age (R = 0.808, p

Published
2022

36. Research on absolute ranging technology of resampling phase comparison method based on FMCW

Author

Sun Bin, Song Junfang, Wang Chao, Li Lanlan, and Tan Linqiu

Subjects
fmcw, absolute ranging, resampling, phase comparison method, laser interference, Physics, QC1-999
Abstract

As an advanced optical precision ranging method, FMCW (frequency-modulated continuous-wave) laser interferometric ranging technology can achieve a large-scale and high-precision absolute distance measurement, so it has high research and application value in the field of coordinate measurement in large space. How to improve the resolution and stability of laser interferometry is a research difficulty in this technology. Based on FMCW laser interferometry relative distance technology, a method for achieving absolute distance measurement through phase comparison after repeated sampling is proposed. Using the FMCW laser distance measuring system, two interference optical paths of measuring interferometer and auxiliary interferometer are constructed, respectively. Synchronous sampling is performed on two interference signals, and the phase ratio of the two interference signals is obtained through the extracted frequency information. The optical path difference of the unknown measurement interferometer is derived from the known auxiliary interferometer information. This method uses a triangular wave modulation laser to reduce the influence of Doppler frequency shift and eliminate quantization errors. By using the fixed-point repeated sampling, the optical path difference information is quickly extracted, and the nonlinear error of laser interference frequency modulation is effectively reduced.

Published
2023
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