Deep-subwavelength features of photonic skyrmions in a confined electromagnetic field with orbital angular momentum

In magnetic materials, skyrmions are nanoscale regions where the orientation of electron spin changes in a vortex-type manner. Here we show that spin-orbit coupling in a focused vector beam results in a skyrmion-like photonic spin distribution of the excited waveguided fields. While diffraction limits the spatial size of intensity distributions, the direction of the field, defining photonic spin, is not subject to this limitation. We demonstrate that the skyrmion spin structure varies on the deep-subwavelength scales down to 1/60 of light wavelength, which corresponds to about 10 nanometre lengthscale. The application of photonic skyrmions may range from high-resolution imaging and precision metrology to quantum technologies and data storage where the spin structure of the field, not its intensity, can be applied to achieve deep-subwavelength optical patterns

NLP From Scratch Without Large-Scale Pretraining: A Simple and Efficient Framework

Pretrained language models have become the standard approach for many NLP tasks due to strong performance, but they are very expensive to train. We propose a simple and efficient learning framework, TLM, that does not rely on large-scale pretraining. Given some labeled task data and a large general corpus, TLM uses task data as queries to retrieve a tiny subset of the general corpus and jointly optimizes the task objective and the language modeling objective from scratch. On eight classification datasets in four domains, TLM achieves results better than or similar to pretrained language models (e.g., RoBERTa-Large) while reducing the training FLOPs by two orders of magnitude. With high accuracy and efficiency, we hope TLM will contribute to democratizing NLP and expediting its development.Comment: 14 pages, 5 figure

Older people in China: their health and the roles of social capital and household income inequality

China is fast becoming an ageing society and this is raising important issues for public health. This study employs nationally representative datasets, the China General Social Surveys and the China Health and Retirement Longitudinal Study, to investigate the relationship between different health outcomes and social capital among older people in China (45 and over). First, the analysis uses binary logistic regression to confirm a significant positive association between subjective measures of individual health and wellbeing and individual-level social capital (measured by social trust, social interaction and membership of organisations and social groups). Second, the analysis combines Difference-In-Difference and Propensity Score Matching to simulate a quasi-experiment designed to identify the causal relationship between social capital and objective health (measured by cognitive function, mental health and physical health). Third, the analysis uses a multilevel modelling strategy to investigate the interrelationships between income inequality, community-level social capital, individual-level social capital and health outcomes. This part of the analysis finds evidence that social capital at the community-level can reduce to some extent the negative association between income inequality and health. Together, the results provide new evidence of the relationship between health, social capital and the distribution of household wealth among older people in China

Numerical study on free vibration characteristics of encastre clinched joints

The present paper deals with free vibration analysis of single lap encastre clinched joints using three dimensional finite element methods. The focus of the analysis is to reveal the influence on the natural frequencies, natural frequency ratios and mode shapes of these joints caused by variations in the material properties of the sheet materials. Numerical examples show that natural frequencies of single lap encastre clinched joints increase significantly as the Young’s modulus of the sheets increase, but only slight changes are encountered for variations of Poisson’s ratios. The mode shapes show that there are different deformations in the jointed section of clinched joints. These different deformations may cause different natural frequency values and different stress distributions. In both cases of transverse free vibration and torsional free vibration, odd mode shapes were found to be symmetrical about the mid-length position and even mode shaps were anti-symmetrical. The amplitudes of vibration at the mid-length of the joints are different for the odd and even modes. The geometry of the lap section is therefore very important and has a very significant effect on the dynamic response of the single lap encastre clinched joints. The main goal of this paper is to give an outline of free vibration characteristics of encastre clinched joints by finite element methods and to provide a basis for further experimental research

Institutional Monitoring, Coordination and Acquisition Decision in Chinese Public Listed Companies

This paper endeavors to explore the roles that institutional investors play in acquisition decision of Chinese Public Listed Companies (PLCs). Acquisition decision is assumed as a cost-benefit analysis process of shareholders as strategic alliances. Using micro data in the Chinese stock market during 2003-2008, we find that institutional investors including Qualified Foreign Institutional Investors (QFII), Social Security Funds (SSF), Security Firms (SF) and Security Investment Funds (SIF), as well as tradable share (TS) concentration affect a PLC’s acquisition likelihood rather than its annual acquisition size. SSF, SIF and TS concentration can increase acquisition likelihood while QFII decrease it. This paper suggests a strategic alliance model in which institutional investors choose whether to coordinate with controlling shareholder and management. Our paper contributes to the published literature in three ways. First, we offer a conceptual framework to understand the coordination process of acquisition decision in China. Second, we identify which institutional investors could benefit from their monitoring on corporate acquisition through better post-acquisition performance and which could not. Third, we investigate whether institutional investors effectively monitor acquisiton decision or just pick cherry