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     

Leslie Y. Yeo 《Biomicrofluidics》2010,4(1)

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.  相似文献   

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

Yücel Çenesiz  Y?ld?ray Keskin  Ayd?n Kurnaz 《Journal of The Franklin Institute》2010,347(2):452-466

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.  相似文献   

A knowledge management perspective on Art Education     

Alton Y.K. Chua  Swee Kiang HengAuthor Vitae 《International Journal of Information Management》2010

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.  相似文献   

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

Yip  D. Y.  Chung  C. M.  Mak  S. Y. 《Journal of Science Education and Technology》1998,7(4):319-328

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.  相似文献   

Aligning work force management practices with competitive priorities and process technology: A conceptual examination     

Ravi Kathuria  Fariborz Y. Partovi 《The Journal of High Technology Management Research》2000,11(2)

Despite the accepted need for strategic alignment in the manufacturing strategy literature, there has been relatively little research aimed at simultaneously aligning decisions in the structural and infrastructural areas with the competitive priorities of an organization. This article attempts to bridge the gap by examining how work force management practices, an infrastructural decision, should be aligned with both the process technology of a manufacturing plant, a structural decision, and its competitive priorities. A conceptual model for linking competitive priorities, process technologies, and work force management practices is presented, and specific and testable propositions are developed for future empirical research. The proposed conceptual model is based on the premise that the process of matching work force management practices to competitive priorities involves identification of the key managerial tasks underlying various competitive priorities. These tasks, in turn, are matched with the process technology characteristics and work force management practices to seek a good fit, which is expected to improve manufacturing performance.  相似文献   

The impact of pictorial stimulus on written expression output of adolescents and adults     

Jason C. Cole  Tracy A. Muenz  Bryan Y. Ouchi  Nadeen L. Kaufman  Alan S. Kaufman 《Psychology in the schools》1997,34(1):1-9

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Effects of footwear midsole thickness on running biomechanics     

Mark H.C. Law  Eric M.F. Choi  Stephanie H.Y. Law  Subrina S.C. Chan  Sonia M.S. Wong 《Journal of sports sciences》2019,37(9):1004-1010

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.  相似文献   

Can a teacher-led RCT improve adolescent girls’ physical self-perception and perceived motor competence?     

Natalie Lander  Judith Mergen  Philip J. Morgan  Jo Salmon  Lisa M. Barnett 《Journal of sports sciences》2019,37(4):357-363

Perceived and actual motor competence (MC) influence physical activity (PA) behaviour. Notably, both are lower in girls than in boys. This study aimed to investigate (i) whether a 12-week, teacher-led intervention that improves actual MC (Lander, N., Morgan, P. J., Salmon, J., & Barnett, L. M. (2017). Improving early-adolescent girls’ motor skill: A cluster randomized controlled trial. Medicine and Science in Sports and Exercise. 49(12), 2498–2505) could also improve adolescent girls’ physical self-perception and perceived MC, and (ii) whether change in actual MC is associated with post-intervention perceptions A randomized controlled trial with 171 girls (mean age 12.48 ± 0.34 years), measured perception (i.e., physical self-perception profile (PSPP) and pictorial scale of perceived movement skill competence (PMSC)) and actual MC (i.e., Victorian FMS Teachers’ Assessment Manual). Mixed models with post-intervention perception as the outcome, adjusting for baseline perception, group, and change in actual MC, as well as clustering, were performed. An interaction term between change in MC and intervention status was included to test the secondary aim. There were significant intervention effects on girls’ physical self-perception as well as their perceived MC. However, there was no association between change in actual MC across the intervention and post intervention perception. While the intervention improved both actual MC and perceived MC, they were not associated.  相似文献   

Coaching athletes with disability: preconceptions and reality     

Y. Wareham  B. Burkett  P. Innes  G. P. Lovell 《Sport in Society》2017,20(9):1185-1202

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.  相似文献   

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

Andy C. Y. Tse  Shirley S. M. Fong  Thomson W. L. Wong  Rich Masters 《European Journal of Sport Science》2017,17(2):152-159

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.  相似文献