Orientation-dependent bending properties of selectively-filled photonic crystal fibres

A selective-filling technique was demonstrated to improve the optical properties of photonic crystal fibres (PCFs). Such a technique can be used to fill one or more fluid samples selectively into desired air holes. The technique is based on drilling a hole or carving a groove on the surface of a PCF to expose selected air holes to atmosphere by the use of a micromachining system comprising of a femtosecond infrared laser and a microscope. The exposed section was immersed into a fluid and the air holes are then filled through the well-known capillarity action [1, 2]. Provided two or more grooves are fabricated on different locations and different orientation along the fibre surface, different fluids may be filled into different air-holes to form a hybrid fibre. As an example, we filled half of a pure-silica PCF by a fluid with n=1.480 by carving a rectangular groove on the fibre (Figure 1). Consequently, the half-filled PCF became a bandgap-guiding structure (upper half), resulted from a higher refractive index in the fluid rods than in the fibre core [3], and three bandgaps were observed within the wavelength range from 600 to 1700 nm. Whereas, the lower half (unfilled holes) of the fibre remains an air/silica index-guiding structure (Figure 1(b)). When the hybrid PCF is bent, its bandgaps gradually narrowed, resulted from the shifts of the bandgap edges. The bandgap edges had distinct bend-sensitivities when the hybrid PCF was bent toward different directions. Especially, the bandgaps are hardly affected when the half-filled PCF was bent toward the fluid-filled region. Such unique bend properties could be used to monitor simultaneously the bend directions and the curvature of the engineering structures

Selectively fluid-filled microstructured optical fibers and applications

A versatile technique based on micromachining is demonstrated to fill selectively one or several different types of fluids into desired air holes in a microstructured optical fiber (MOF). Unique optical properties and applications of the selective-filled MOF are investigated

Exploring the Moderating Effects of Commitment and Perceived Value of Knowledge in Explaining Knowledge Contribution in Virtual Communities

Motivating people to contribute knowledge to others has become a major challenge in knowledge management. To help understand knowledge contribution in virtual communities (VCs)—a popular area for knowledge sharing, this study investigates individuals’ motivations to contribute knowledge based on the nature of knowledge contribution behavior. In particular, the influences of two key moderating variables which have been neglected in most previous studies are examined. The theoretical model is empirically tested using data collected from 363 VC members. We find that reciprocity, reputation, knowledge self-efficacy, enjoyment in helping others and commitment are key factors of four kinds (egoism, altruism, collectivism and principlism) that significantly and directly influence individuals’ knowledge contribution intention in VCs. Perceived value of knowledge (PVK) is found to be an important moderator of the relationships between reciprocity, enjoyment in helping others and knowledge contribution intention. We confirm that commitment reduces the impact of reputation on knowledge contribution intention. Implications for both researchers and practitioners are discussed

Customer Engagement in an Online Social Platform: A Conceptual Model and Scale Development

The rise of new media channels in the last few years has changed the ways customers communicate and exchange information. Managing customer relationships through social media engagement has become an important component of successful electronic marketing strategies. Though the concept of customer engagement has received considerable attention in the business community, there is a paucity of theory-guided empirical research in customer engagement in an online social platform. More importantly, there is a lack of consensus regarding its definition, forms, dimensionality, and operationalization. This study addresses these limitations in part by theoretically conceptualizing and empirically validating a scale to measure customer engagement in an online social platform. In this research-in-progress paper, we present our conceptual model of customer engagement and propose a rigorous approach in scale development and validation. The authors believe that this research will contribute to the development of online community literature and add to the repository of rigorous research instruments for researchers to use

Appraisal Analysis on Lecture Discourse of ELF Lecturers Teaching Content Subjects at An EMI University in China

This study focuses specifically on the lecture discourse of academics working in a Chinese EMI universitywhen teaching different disciplines using English as the academic lingua franca. The aim of the study is to investigate linguistic patterns of evaluative language used by university lecturers and to describe how evaluative meanings are encoded; in other words, establishing a pattern of what is appraised and how it is appraised in academic lectures. The linguistic data of this research is real-time lecture discourse recorded from 12 lecturers teaching content courses in humanities and hard sciences; all of the transcribed spoken data of this research were coded using the framework of appraisal in SFL (systemic functional grammar). All the appraisal expressions identified in this current study have been defined as appraisal signals, i.e., attitude signal, engagement signal, graduation signal. These expressions can be regarded as discourse signals embedded in the lecture discourse and the research focus of this current study is to describe how EMI academics use appraisal expressions to signal their evaluative meanings in academic lectures. Results show that the meaning of an appraisal signal is closely associated with its co-text. The linguistic meanings of suchco-text may refer to the referents being evaluated in the verbal context, some frequently used pronoun patterns, and lecturers’ modulations of the evaluative meanings and their flexible use of integrating different types of appraisal signals. Findings regarding the disciplinary differences and ELF features of the appraisal signals have also been discussed. It can be concluded that appraisal signals are useful linguistic devices to enhance communicativeness of the lecture discourse in use and essential to the clarity and mutual intelligibility of the ELF communication in academic lectures at EMI universities

Relative Entropy in CFT

By using Araki's relative entropy, Lieb's convexity and the theory of singular integrals, we compute the mutual information associated with free fermions, and we deduce many results about entropies for chiral CFT's which are embedded into free fermions, and their extensions. Such relative entropies in CFT are here computed explicitly for the first time in a mathematical rigorous way. Our results agree with previous computations by physicists based on heuristic arguments; in addition we uncover a surprising connection with the theory of subfactors, in particular by showing that a certain duality, which is argued to be true on physical grounds, is in fact violated if the global dimension of the conformal net is greater than $1.$Comment: 31 page

User Satisfaction with Virtual Social Community: The Case of Bulletin Board Systems

Building upon expectation confirmation theory and elaboration likelihood model, this study proposed and empirically tested a research model of user satisfaction with virtual social community. An online questionnaire was posted in the Bulletin Board Systems of a local university in Mainland China. A total of 240 online questionnaires were collected, and the data was analyzed using partial least squares. The research model provided over 70 percent of variance explained in user satisfaction with virtual social community. Relevance and comprehensiveness of messages, and disconfirmations of relevance and accuracy of messages are found statistically significant. The dimensions of perceived source credibility (including source expertise and source trustworthiness) are not found significant, but their disconfirmations are found statistically significant. Implications of this study are noteworthy for both researchers and practitioners