Micro-optofluidic Lenses: A review

This review presents a systematic perspective on the development of micro-optofluidic lenses. The progress on the development of micro-optofluidic lenses are illustrated by example from recent literature. The advantage of micro-optofluidic lenses over solid lens systems is their tunability without the use of large actuators such as servo motors. Depending on the relative orientation of light path and the substrate surface, micro-optofluidic lenses can be categorized as in-plane or out-of-plane lenses. However, this review will focus on the tunability of the lenses and categorizes them according to the concept of tunability. Micro-optofluidic lenses can be either tuned by the liquid in use or by the shape of the lens. Micro-optofluidic lenses with tunable shape are categorized according to the actuation schemes. Typical parameters of micro-optofluidic lenses reported recently are compared and discussed. Finally, perspectives are given for future works in this field.     

Towards an understanding of dynamics among teachers,teacher leaders,and administrators in a teacher-led school reform

A substantial amount of professional development and implementation has moved towards teachers and teacher leaders in recent years. Previous works have examined how teachers, teacher leaders, or administrators perceive teacher leadership in school reforms, but few have advanced all three perspectives simultaneously. Drawing upon over 200 interviews, we examine how leadership is distributed and the tensions and dynamics arising among these three groups in a teacher-led school reform. Two main themes emerged from our analysis: minimizing conflicts with teachers was important to teacher leaders, and the distribution of leadership between administrators and teacher leaders changed the status and normative roles of teacher leaders.     

On the vein-stiffening membrane structure of a dragonfly hind wing

Aiming at exploring the excellent structural performance of the vein-stiffening membrane structure of dragonfly hind wings, we analyzed two planar computational models and three 3D computational models with cambered corrugation based on the finite element method. It is shown that the vein size in different zones is proportional to the magnitude of the vein internal force when the wing structure is subjected to uniform out-of-plane transverse loading. The membrane contributes little to the flexural stiffness of the planar wing models, while exerting an immense impact upon the stiffness of the 3D wing models with cambered corrugation. If a lumped mass of 10% of the wing is fixed on the leading edge close to the wing tip, the wing fundamental fre- quency decreases by 10.7%-13.2%; if a lumped mass is connected to the wing via multiple springs, the wing fundamental frequency decreases by 16.0%-18.0%. Such decrease in fundamental frequency explains the special function of the wing pterostigma in alleviating the wing quivering effect. These particular features of dragonfly wings can be mimicked in the design of new-style reticulately stiffening thin-walled roof systems and flapping wings in novel intelligent aerial vehicles.     

Comparison of 3D reconstructive technologies used for morphometric research and the translation of knowledge using a decision matrix

The use of three‐dimensional (3D) models for education, pre‐operative assessment, presurgical planning, and measurement have become more prevalent. With the increase in prevalence of 3D models there has also been an increase in 3D reconstructive software programs that are used to create these models. These software programs differ in reconstruction concepts, operating system requirements, user features, cost, and no one program has emerged as the standard. The purpose of this study was to conduct a systematic comparison of three widely available 3D reconstructive software programs, Amira^®, OsiriX, and Mimics^®, with respect to the software's ability to be used in two broad themes: morphometric research and education to translate morphological knowledge. Cost, system requirements, and inherent features of each program were compared. A novel concept selection tool, a decision matrix, was used to objectify comparisons of usability of the interface, quality of the output, and efficiency of the tools. Findings indicate that Mimics was the best‐suited program for construction of 3D anatomical models and morphometric analysis, but for creating a learning tool the results were less clear. OsiriX was very user‐friendly; however, it had limited capabilities. Conversely, although Amira had endless potential and could create complex dynamic videos, it had a challenging interface. These results provide a resource for morphometric researchers and educators to assist the selection of appropriate reconstruction programs when starting a new 3D modeling project. Anat Sci Educ 6: 393–403. © 2013 American Association of Anatomists.     

Micromixer based on viscoelastic flow instability at low Reynolds number

We exploited the viscoelasticity of biocompatible dilute polymeric solutions, namely, dilute poly(ethylene oxide) solutions, to significantly enhance mixing in microfluidic devices at a very small Reynolds number, i.e., Re≈0.023, but large Peclet and elasticity numbers. With an abrupt contraction microgeometry (8:1 contraction ratio), two different dilute poly(ethylene oxide) solutions were successfully mixed with a short flow length at a relatively fast mixing time of <10 μs. Microparticle image velocimetry was employed in our investigations to characterize the flow fields. The increase in velocity fluctuation with an increase in flow rate and Deborah number indicates the increase in viscoelastic flow instability. Mixing efficiency was characterized by fluorescent concentration measurements. Our results showed that enhanced mixing can be achieved through viscoelastic flow instability under situations where molecular-diffusion and inertia effects are negligible. This approach bypasses the laminar flow limitation, usually associated with a low Reynolds number, which is not conducive to mixing.     

Neural information retrieval: at the end of the early years

A recent “third wave” of neural network (NN) approaches now delivers state-of-the-art performance in many machine learning tasks, spanning speech recognition, computer vision, and natural language processing. Because these modern NNs often comprise multiple interconnected layers, work in this area is often referred to as deep learning. Recent years have witnessed an explosive growth of research into NN-based approaches to information retrieval (IR). A significant body of work has now been created. In this paper, we survey the current landscape of Neural IR research, paying special attention to the use of learned distributed representations of textual units. We highlight the successes of neural IR thus far, catalog obstacles to its wider adoption, and suggest potentially promising directions for future research.     

Why Do University Students Refrain from Using E-Books in Libraries? Empirical Evidence from Vietnam

E-books have increasingly penetrated the academic world. However, despite efforts from Vietnamese universities and colleges to establish and broaden their e-books collection, students seem reluctant to use these digital books. This study aims to examine the barriers to using e-books in libraries among Vietnamese students. Data were obtained from 355 undergraduate students who were interested in e-books. The findings demonstrate that some key barriers impeding students from using e-books include the lack of computers and e-books in libraries, limited information and knowledge about e-books and their preference of using print books. Interestingly, female students tend to perceive the barriers to be stronger than their male counterparts. This study’s findings have important implications for universities, libraries and publishers who seek to promote e-books to students.     

Promoting the Purchase of Textbooks in the Vietnamese Higher Education Sector

Higher education textbooks sales account for a significant portion of the overall book market. This study makes an important contribution to the extant literature by examining students’ purchase of original textbooks in a developing market, Vietnam. Notably, it seeks to investigate why students do not purchase original textbooks as well as the difference in purchase behavior between different groups of students. The findings reveal that some key obstacles to students’ purchase behavior include high prices, insufficient availability, low perceived value, and the emergence of pirated textbooks. Another notable finding is that senior students who are female tend to purchase more textbooks. In light of these findings, marketing strategies are suggested for publishers, bookstores and universities who aim to promote the sales and consumption of original textbooks.     

Public Opinion Polls,Chicken Soup and Sample Size

Cooking and tasting chicken soup in three different pots of very different size serves to demonstrate that it is the absolute sample size that matters the most in determining the accuracy of the findings of the poll, not the relative sample size, i.e. the size of the sample in relation to its population.