Preface to Special Topic: Papers from the 13th International Conference on Surface and Colloid Science (ICSCS) and the 83rd ACS Colloid and Surface Science Symposium, Columbia University, New York, 2009

This Special Topic section is a compilation of several original contributions covering both fundamental and practical aspects of electrokinetic microfluidic phenomena that were presented during the Electrokinetics and Microfluidics sessions held at the conference.Electrokinetics is currently the mechanism of choice for the manipulation of fluids as well as colloidal and biological particles at microscale and nanoscale dimensions.¹ The popularity of electrokinetics is perhaps not so surprising as electrodes are easy to fabricate and embed into microfluidic chips, thus allowing the entire fluid and particle actuation mechanism to be completely integrated into the device. In addition, driving microfluidics with electric fields is relatively straightforward and allows for precise actuation. Nevertheless, considerable challenges remain in understanding the complex mechanisms associated with the hydrodynamics of conducting and dielectric fluids and particles under the influence of electric fields. Concomitantly, there has been an exponential increase in research and development in this field along both fundamental and applied themes in the past five years.This sustained growth in the microfluidics community of electrokinetics research has led to a sequel to the first Electrokinetic Phenomena and Microfluidics session at the 82nd ACS Colloid and Surface Science Symposium in Raleigh, NC, in 2008, and which we hope will now be a regular feature at successive ACS Colloid and Surface Science meetings. This year at the combined 2009 13th International Conference on Surface and Colloid Science (ICSCS) and the 83rd ACS Colloid and Surface Science Symposium in New York, the Electrokinetics and Microfluidics symposium proved to be extremely popular, with three keynote lectures presented by Professor Howard Stone, Professor Hsueh-Chia Chang, and Professor Thomas Healy, and 44 oral presentations. In both 2008 and 2009, Biomicrofluidics has organized a special issue to cover some of the contributions reported at these meetings.²The growing interest in using electric fields to manipulate biological entities such as cells, DNA, and even single molecules is reflected in this year’s collection of papers with dielectrophoretic (DEP) phenomena comprising the bulk of the contributions. In Ref. ³, a new theory to describe Stern layer conductance along the surface of nanocolloids is proposed, forming the basis for the derivation of a more accurate prediction of the DEP crossover frequency. This theory is then employed to determine the conformation and, hence, optimum coverage of oligonucleotides on the surface of nanocolloid functionalized molecular probes during DNA hybridization under the influence of DEP, which can be exploited for biomolecular sensing. Other fundamental DEP papers include the investigation of particle motion under DEP induced optically via a photoconductor, in which Zhu et al.⁴ characterized the frequency dependence of the motion through the synchronous velocity spectra of the particles, and a numerical study of particle trapping at the throat of converging-diverging microchannels under the influence of negative DEP using a transient arbitrary Lagrangian–Eulerian finite element method.⁵ A more practical implementation is, on the other hand, reported by Yang et al.⁶ in which the negative DEP is exploited to separate colorectal cancer cells from other cells in a microfluidic device as a demonstration of a portable cancer detection tool.Continuing along the separation theme, but with regard to DNA separation using pulsed-field gel electrophoresis aided by sparse but regularly ordered microfabricated arrays of nanoposts, is a Brownian dynamics simulation model reported by Ou et al.⁷ in which DNA channeling, which predicts that the motion of DNA is undisturbed by the presence of arrays for large spacing to DNA equilibrium size ratios and when the field lines are straight, is predicted, consistent with experimental observations. In another fundamental paper, a direct numerical simulation model is presented to predict the current-voltage relationship across conducting pores along cell membranes, which is of fundamental importance in the electroporation process.⁸We hope that you will enjoy reading the contributions in this special topic and that it encourages you to participate in future Electrokinetics and Microfluidics meetings at the ACS Colloid and Surface Science Symposia, which we definitely hope will continue on a regular basis.     

The solution of the Bagley-Torvik equation with the generalized Taylor collocation method

In this paper, the Bagley-Torvik equation, which has an important role in fractional calculus, is solved by generalizing the Taylor collocation method. The proposed method has a new algorithm for solving fractional differential equations. This new method has many advantages over variety of numerical approximations for solving fractional differential equations. To assess the effectiveness and preciseness of the method, results are compared with other numerical approaches. Since the Bagley-Torvik equation represents a general form of the fractional problems, its solution can give many ideas about the solution of similar problems in fractional differential equations.     

A knowledge management perspective on Art Education

This paper applies concepts drawn from KM to Art Education. Specifically, the purpose of this paper is to study the knowledge types, knowledge sources, knowledge processes as well as factors affecting these processes in Art Education. The research was carried out using an interpretative case study methodology in Singapore. Apart from 26 one-to-one interviews conducted with various stakeholders of the Art Education community, on-site observations were made at 19 different Art Education events. Four major findings emerged. One, the knowledge types of Art Education in Singapore were a blend of different knowledge domains. Two, perceptible knowledge sources were those which conveyed an appearance of authority. Three, knowledge processes in Art Education were steeply humanistic. Finally, factors that affected knowledge processes were (i) the highly competitive Singapore education system, (ii) management support and policies, (iii) personal values and interests, (iv) workload and (v) the absorptive capacity of Art teachers. This paper concludes with a number of research and practical implications.     

The Subject Matter Knowledge in Physics Related Topics of Hong Kong Junior Secondary Science Teachers

The subject matter competence in physics related topics of 147 inservice junior secondary science teachers in Hong Kong was identified using a true-or-false instrument based on a framework conceptualized by the authors. The findings of this study showed that teachers are weak both in factual knowledge and conceptions in these topics. Although physics majors outperform nonphysics majors significantly in the test, their own performance is by no means satisfactory on criterion referenced terms. Items incorrectly answered by over 40% of the teachers are listed with corrections given. The sources of conceptual mistakes and specific remedial measures were elaborated for items incorrectly answered by more than 60% of the teachers. General implications and possibilities for improvement in tertiary education, science teaching, and teacher education were discussed.     

Investigation of snowboard stiffness and camber characteristics for different riding styles

Previous research has indicated that the flex pattern and camber of a snowboard are crucial to its perceived “feel”, or the physical and psychological feedback given to the rider whilst snowboarding. These features are the primary cause of variation in snowboard performance for different riding styles. Consequently, this article deals with the identification of stiffness and camber characteristics for freestyle, freeride and versatile test boards, and their statistical correlation to a comprehensive list of qualitative feel-based performance requirements. It has been determined that the test boards spanning the major styles all possessed similar bending profiles, that were highly representative of each snowboard’s respective thickness distribution. The torsional stiffness curves however appeared to be driven by the composite architecture used in construction. Unsurprisingly, the freeride test board showed the greatest level of overall stiffness. The versatile board exhibited the greatest fluctuation in bending stiffness along the chord, whereas the freestyle profile was far more even throughout, with less variation from tip to tail. All of the subjective performance parameters except forgiveness showed positive associations to the body stiffness and camber, with manoeuvrability exhibiting the strongest correlations. The forgiveness showed the exact opposite trend, implying that higher levels of flex and less camber promotes a forgiving snowboard.     

The effect of biofeedback training on affective regulation and simulated car-racing performance: a multiple case study analysis

The foundation of this study was based on an idiosyncratic concept, which uses probabilistic determinations (Kamata, Tenenbaum, & Hanin, 2002) to verify the utility and effectiveness of a biofeedback intervention by manipulating affective performance states in a race-car simulator. Nine males completed five separate time-trials of a simulated racing task and were then randomly assigned to one of three arousal regulation treatment conditions: (1) optimal, (2) poor, and (3) attention control. Following the biofeedback intervention, participants underwent another series of race trials to determine the effectiveness of the arousal regulation intervention. The results indicated that there were relative similarities in the strength and direction of the perceived and physiological states between the participants; however, the subtle details of the participants' unique performance zones and the probability of achieving each zone were revealed to be unique among the participants. The results also indicated that: (a) the biofeedback manipulation resulted in the expected changes for each participant, and (b) there were some large individual differences among the participants, necessitating the idiosyncratic approach. Limitations and future directions are also addressed.     

Effects of footwear midsole thickness on running biomechanics

Shoe manufacturers launch running shoes with increased (e.g., maximalists) or decreased (e.g., minimalists) midsole thickness and claim that they may prevent running injury. Previous studies tested footwear models with different midsole thicknesses on the market but the shoe construct was not strictly comparable. Therefore, in the present study, we examined the effect of midsole thickness, from 1-mm to 29-mm, in a standard test shoe prototype on the vertical loading rates, footstrike angle and temporal spatial parameters in distance runners. Fifteen male habitual rearfoot strikers were recruited from local running clubs. They were asked to run on an instrumented treadmill in shoes with different midsole thicknesses. We found significant interactions between midsole thickness with vertical loading rates (p < 0.001), footstrike angle (p = 0.013), contact time (p < 0.001), cadence (p = 0.003), and stride length (p = 0.004). Specifically, shoes with thinner midsole (1- and 5-mm) significantly increased the vertical loading rates and shortened the contact time, when compared with thicker midsole shoes (25- and 29-mm). However, we did not observe any substantial differences in the footstrike angle, cadence and stride length between other shod conditions. The present study provides biomechanical data regarding the relationship between full spectrum midsole thicknesses and running biomechanics in a group of rearfoot strikers.     

Coaching athletes with disability: preconceptions and reality

It is now widely recognized that athletes with disability compete at an elite level which parallels that experienced by non-disabled athletes. The importance of quality coaching to develop an athlete’s full potential is similarly recognized. However, research in the area of coaching athletes with disability is still lacking compared to its counterpart in non-disabled sport. This research explored the holistic experience of coaching elite athletes with disability, and therefore encompassed not only the coaches’ preconceptions, but the rewards and challenges of their coaching experience. Semi-structured interviews were held with 12 coaches of elite athletes from sports including swimming, athletics, cycling, canoeing, triathlon, equestrian sport and wheelchair basketball. The results of the study identified that, although the coaches reported their experience as being overwhelmingly positive, they were also regularly confronted with difficulties not generally faced by coaches of non-disabled athletes.     

Analogy motor learning by young children: a study of rope skipping

Research in psychology suggests that provision of an instruction by analogy can enhance acquisition and understanding of knowledge. Limited research has been conducted to test this proposition in motor learning by children. The purpose of the present study was to examine the feasibility of analogy instructions in motor skill acquisition by children. Thirty-two children were randomly assigned to one of the two instruction protocols: analogy and explicit instruction protocols for a two-week rope skipping training. Each participant completed a pretest (Lesson 1), three practice sessions (Lesson 2–4), a posttest and a secondary task test (Lesson 5). Children in the analogy protocol displayed better rope skip performance than those in the explicit instruction protocol (p?<?.001). Moreover, a cognitive secondary task test indicated that children in the analogy protocol performed more effectively, whereas children in the explicit protocol displayed decrements in performance. Analogy learning may aid children to acquire complex motor skills, and have potential benefits related to reduced cognitive processing requirements.     

Another May Fourth

The May Fourth Movement is most often understood as a precursor to the China that emerged under the rule of Mao Zedong and the Chinese Communist Party. In this essay, Mizoguchi presents an alternative reading of May Fourth, one envisioned by Liang Shuming as more deeply rooted in Chinese tradition than the heavily Marxian, class-based May Fourth later positioned as the forebear of the Cultural Revolution.