Historical Objections Against the Number Line     

Albrecht Heeffer 《Science & Education》2011,20(9):863-880

Historical studies on the development of mathematical concepts will help mathematics teachers to relate their students’ difficulties in understanding to conceptual problems in the history of mathematics. We argue that one popular tool for teaching about numbers, the number line, may not be fit for early teaching of operations involving negative numbers. Our arguments are drawn from the many discussions on negative numbers during the seventeenth and eighteenth centuries from philosophers and mathematicians such as Arnauld, Leibniz, Wallis, Euler and d’Alembert. Not only does division by negative numbers pose problems for the number line, but even the very idea of quantities smaller than nothing has been challenged. Drawing lessons from the history of mathematics, we argue for the introduction of negative numbers in education within the context of symbolic operations.  相似文献   

Career development influences of international students who pursue permanent immigration to Canada     

Nancy Arthur  Sarah Flynn 《International Journal for Educational and Vocational Guidance》2011,11(3):221-237

This research focused on the career decision and planning needs of a unique group of migrants: international students who are completing their studies as temporary immigrants and who are embarking on the career journey of employment and permanent immigration. A semi-structured interview employing a Critical Incident Technique was used to assess the career influences of 19 undergraduate and graduate international students at a Canadian university. Data were analyzed using a constant comparison method and critical incident protocol. Students were motivated to remain in Canada due to enhanced job opportunities and high standard of living. Barriers to migration included the fear of not securing employment and cultural and linguistic barriers. International students would like to see campus and career services specified to the needs of international and graduate students to help them realize their goal of pursuing employment as the key to permanent immigration.  相似文献   

Integrated carbon fiber electrodes within hollow polymer microneedles for transdermal electrochemical sensing     

Miller PR  Gittard SD  Edwards TL  Lopez DM  Xiao X  Wheeler DR  Monteiro-Riviere NA  Brozik SM  Polsky R  Narayan RJ 《Biomicrofluidics》2011,5(1):13415

In this study, carbon fiber electrodes were incorporated within a hollow microneedle array, which was fabricated using a digital micromirror device-based stereolithography instrument. Cell proliferation on the acrylate-based polymer used in microneedle fabrication was examined with human dermal fibroblasts and neonatal human epidermal keratinocytes. Studies involving full-thickness cadaveric porcine skin and trypan blue dye demonstrated that the hollow microneedles remained intact after puncturing the outermost layer of cadaveric porcine skin. The carbon fibers underwent chemical modification in order to enable detection of hydrogen peroxide and ascorbic acid; electrochemical measurements were demonstrated using integrated electrode-hollow microneedle devices.  相似文献   

Individualism-collectivism and business context as predictors of behaviors in cross-national work settings: Incidence and outcomes     

Peter B. Smith  Cláudio V. TorresAlena Chudzikova  Serdar DegirmenciogluFrancisco Donoso-Maluf  Nancy Chen Yi FengCharles Harb  Brad JacksonSigmar Malvezzi  Andrew MogajiJuan Carlos Pastor  Lorena Perez-FlorianoB.N. Srivastava  Günter StahlStephanie Thomason  Vladimir Yanchuk 《Int J Intercult Relat》2011,35(4):440-451

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Effect of different swim caps on the assessment of body volume and percentage body fat by air displacement plethysmography     

Peeters MW  Claessens AL 《Journal of sports sciences》2011,29(2):191-196

Isothermal air trapped in scalp hair generates an underestimation of body volume when it is measured by air displacement plethysmography. The aim of this study was to examine the effect of wearing different types of swim caps on the measurement of body volume and percentage body fat by air displacement plethysmography. It was hypothesized that wearing a silicone swim cap would more thoroughly compress scalp hair compared with a lycra swim cap, yielding higher estimates of body volume and percent body fat. Thirty female participants aged 25.7 ± 6.4 years were measured in random order when wearing no swim cap, a lycra swim cap or a silicone swim cap. For the no-cap versus lycra cap condition, the mean bias for body volume was -0.579 ± 0.380 litre (limits of agreement: -1.340 to 0.181 litre) and for percent fat -4.9 ± 3.1% fat (limits of agreement: -11.2 to 1.3% fat) (P < 0.05). For the silicone versus lycra condition, the mean bias for body volume was 0.137 ± 0.099 litre (limits of agreement: -0.062 to 0.335 litre) and for percent fat 1.2 ± 0.9% fat (limits of agreement: -0.5 to 2.9% fat) (P < 0.05). In conclusion, attention should be paid to optimal compression of isothermal air trapped in scalp hair when using air displacement plethysmography. The present results suggest that this compression may be more thorough when wearing a silicone swim cap.  相似文献   

Early Childhood Teachers’ Perceptions of the Effectiveness of Their Elementary School’s Approach to Social Emotional Learning: A Mixed Methods Study     

Steed  Elizabeth A.  Shapland  Dorothy  Leech  Nancy 《Early Childhood Education Journal》2022,50(7):1121-1132

Early Childhood Education Journal - The promotion of Social emotional learning (SEL) in elementary schools has increased; however, little is known about early childhood teachers’ perceptions...  相似文献   

We’ve Come a Long Way,Baby— A pictorial look at our roots     

Nancy Klinck 《TechTrends》1989,34(4):28-31

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Barbarians at the gates: a half-century of unaffiliated users in academic libraries     

Nancy Courtney   《The Journal of Academic Librarianship》2001,27(6)

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Synchronized videotape teletraining     

Nancy G. Sickler 《TechTrends》1993,38(6):23-24

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An organizational analysis of student teacher supervision     

Michael Diamonti  Nancy Diamonti 《Interchange》1975,6(4):27-33

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