Three dimensional passivated-electrode insulator-based dielectrophoresis     

Diana Nakidde  Phillip Zellner  Mohammad Mehdi Alemi  Tyler Shake  Yahya Hosseini  Maria V. Riquelme  Amy Pruden  Masoud Agah 《Biomicrofluidics》2015,9(1)

In this study, a 3D passivated-electrode, insulator-based dielectrophoresis microchip (3D πDEP) is presented. This technology combines the benefits of electrode-based DEP, insulator-based DEP, and three dimensional insulating features with the goal of improving trapping efficiency of biological species at low applied signals and fostering wide frequency range operation of the microfluidic device. The 3D πDEP chips were fabricated by making 3D structures in silicon using reactive ion etching. The reusable electrodes are deposited on second glass substrate and then aligned to the microfluidic channel to capacitively couple the electric signal through a 100 μm glass slide. The 3D insulating structures generate high electric field gradients, which ultimately increases the DEP force. To demonstrate the capabilities of 3D πDEP, Staphylococcus aureus was trapped from water samples under varied electrical environments. Trapping efficiencies of 100% were obtained at flow rates as high as 350 μl/h and 70% at flow rates as high as 750 μl/h. Additionally, for live bacteria samples, 100% trapping was demonstrated over a wide frequency range from 50 to 400 kHz with an amplitude applied signal of 200 Vpp. 20% trapping of bacteria was observed at applied voltages as low as 50 Vpp. We demonstrate selective trapping of live and dead bacteria at frequencies ranging from 30 to 60 kHz at 400 Vpp with over 90% of the live bacteria trapped while most of the dead bacteria escape.  相似文献   

The Role of Mediators in the Development of Longitudinal Mathematics Achievement Associations          下载免费PDF全文

Tyler W. Watts  Greg J. Duncan  Meichu Chen  Amy Claessens  Pamela E. Davis‐Kean  Kathryn Duckworth  Mimi Engel  Robert Siegler  Maria I. Susperreguy 《Child development》2015,86(6):1892-1907

Despite research demonstrating a strong association between early and later mathematics achievement, few studies have investigated mediators of this association. Using longitudinal data (n = 1,362), this study tested the extent to which mathematics self‐concepts, school placement, executive functioning, and proficiency in fractions and division account for the association between mathematics achievement in first grade and at age 15. As hypothesized, a strong longitudinal association between first‐grade and adolescent mathematics achievement was present (β = .36) even after controlling for a host of background characteristics, including cognitive skills and reading ability. The mediators accounted for 39% of this association, with mathematics self‐concept, gifted and talented placement, and knowledge of fractions and division serving as significant mediators.  相似文献   

What Others Say     

Laura Terry Tyler 《Clearing house (Menasha, Wis.)》2013,86(9):559-560

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信息安全的经济学(之二)     

Ross Anderson  Tyler Moore  陆俊秀 《中国教育网络》2008,(1):31-33

信息安全的经济学近来已经成为一门蓬勃发展的学科。由于分布式系统通常是由那些属于不同利益主体的计算机构成,我们发现在实现可靠性的过程中,激励机制变得和纯技术设计一样重要。这一学科领域不仅为那些传统的安全课题提供了洞见,而且还为更宽泛的领域中的研究难题拓展了思路,诸如:P2P系统设计,程序员和测试员的最优比例,隐私为何不断被侵蚀,以及数字版权管理等问题。本刊上期和本期推荐剑桥大学计算机实验室的Ross Anderson和Tyler Moore在2006年10月27日的《科学》杂志上刊发的《信息安全的经济学(The Economics of Information Security)》一文,介绍这一学科的研究和发展,以资借鉴。  相似文献   

Why women succeed,and fail,in the arts   总被引：1，自引：1，他引：0  

Tyler Cowen 《Journal of Cultural Economics》1996,20(2):93-113

I examine and test hypotheses for the differential performance of men and women in the arts. I consider whether observed outcomes are best accounted for by differing innate and genetic endowments across the sexes, variations in training opportunities, maternal responsibilities, or discrimination in the marketplace. More generally, I also consider how social mechanisms can give rise to observed patterns of unequal achievement.  相似文献   

Teachers' Responses to the Ecosystemic Approach to Changing Chronic Problem Behaviour in Schools     

Ken Tyler  & Brynley David Jones 《Pastoral Care in Education》2002,20(2):30-39

This paper discusses the responses of a group of thirty-three primary and two secondary teachers to a series of sessions in which the ecosystemic approach to changing chronic problem behaviour in schools was explained and then tried out in practice. Three case examples are presented, as well as related discussions, which illustrate the approach. This study follows on from the work reported in Pastoral Care , December 1998.  相似文献   

Staying On: Poverty Warriors in West Virginia     

Marie Tyler McGraw 《Journal of American culture (Malden, Mass. : 2003)》1985,8(4):93-103

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"Now the African reigns supreme": the rise of African boxing on the Witwatersrand, 1924-1959     

Fleming T 《国际体育史杂志》2011,28(1):47-62

This essay explores the growth of boxing among the African populations on the Witwatersrand region of South Africa between 1924 and 1959. It details how the sport's jump in popularity with Africans paralleled migration to Johannesburg. Africans increasingly saw boxing as an activity and skill conducive with survival in this new environment, and thus the sport grew in popularity, stature, and skill-level amongst this emergent urban population. The essay further explores the various ways that the sport was disseminated and popularized during the era, thus detailing how the sport reached both the African masses and petit-bourgeois educated elite. As their presence in Johannesburg became more and more permanent, boxing came to encompass various meanings and ideals, such as notions of discipline, independence and civility, to these urban populations.  相似文献   

Hitting promotion hard: A network response to channel surfing and new competition     

Susan Tyler Eastman  Gregory D. Newton 《Journal of Applied Communication Research》2013,41(1):73-85

Examination of over 600 on‐air promos carried within or adjacent to situation comedies showed that the promos’ salience impacted the ratings of the promoted program. After controlling for the ratings of the lead‐in to the promoted program, significant associations were found for the method of construction of the promo, the familiarity of the promoted program, the amount of clutter within breaks, the position of the promo within the break, and the rating of the program carrying the promotion. The results suggested a six‐part model for maximizing the effectiveness of on‐air promotion.  相似文献   

How Promotional Content Changes Ratings: The Impact of Appeals,Humor, and Presentation     

Susan Tyler Eastman  Gregory D. Newton  Paul D. Bolls 《Journal of Applied Communication Research》2013,41(3):238-259

This study assessed the impact of content--as opposed to structural--factors on television program ratings, seeking to locate clusters of components that would identify effective on-air promotion and allocate content a better-defined place within theoretic models of media priming. Stepwise multiple regression analyses of 1,547 on-air promos for 155 prime-time programs demonstrated that 5-9% of ratings variance was accounted for by content appeals, humor, and presentation in promos for comedy programs. The influence of content variables was greater for familiar than unfamiliar comedies, and humor and presentation in promos contributed to variance in ratings for mid-rated but not high- or low-rated comedies.  相似文献