Aerodynamic drag in cycling: methods of assessment

When cycling on level ground at a speed greater than 14 m/s, aerodynamic drag is the most important resistive force. About 90% of the total mechanical power output is necessary to overcome it. Aerodynamic drag is mainly affected by the effective frontal area which is the product of the projected frontal area and the coefficient of drag. The effective frontal area represents the position of the cyclist on the bicycle and the aerodynamics of the cyclist-bicycle system in this position. In order to optimise performance, estimation of these parameters is necessary. The aim of this study is to describe and comment on the methods used during the last 30 years for the evaluation of the effective frontal area and the projected frontal area in cycling, in both laboratory and actual conditions. Most of the field methods are not expensive and can be realised with few materials, providing valid results in comparison with the reference method in aerodynamics, the wind tunnel. Finally, knowledge of these parameters can be useful in practice or to create theoretical models of cycling performance.     

Microarray of non-connected gold pads used as high density electric traps for parallelized pairing and fusion of cells

Cell fusion consists of inducing the formation of a hybridoma cell containing the genetic properties of the progenitor cells. Such an operation is usually performed chemically or electrically. The latter method, named electrofusion, is considered as having a strong potential, due to its efficiency and non-toxicity, but deserves further investigations prior to being applicable for key applications like antibody production and cancer immunotherapy. Indeed, to envision such applications, a high amount of hybrid cells is needed. In this context, we present in this paper a device for massive cell pairing and electrofusion, using a microarray of non-connected conductive pads. The electrofusion chamber––or channel––exposes cells to an inhomogeneous electric field, caused by the pads array, enabling the trapping and pairing of cells with dielectrophoresis (DEP) forces prior to electrofusion. Compared to a mechanical trapping, such electric trapping is fully reversible (on/off handling). The DEP force is contactless and thus eases the release of the produced hybridoma. Moreover, the absence of wire connections on the pads permits the high density trapping and electrofusion of cells. In this paper, the electric field mapping, the effect of metallic pads thickness, and the transmembrane potential of cells are studied based on a numerical model to optimize the device. Electric calculations and experiments were conducted to evaluate the trapping force. The structure was finally validated for cell pairing and electrofusion of arrays of cells. We believe that our approach of fully electric trapping with a simple structure is a promising method for massive production of electrofused hybridoma.     

School climate and teacher beliefs in a school effectively serving poor South Carolina (USA) African-American students: A case study

This study examined the roles of school climate, teacher expectations, and instructional practices in one elementary school in South Carolina (USA) that produced effective achievement outcomes with poor and minority students. Survey data, teacher interviews, and classroom videotaping was used to identify school characteristics and instructional behaviors of six teachers nominated by colleagues as exemplary. The school was characterized by an emphasis on high student expectations, school staff cohesiveness, engaging instruction, high parent involvement, and multicultural instruction integrated with curriculum. The practices identified are consistent with literature on effective American schools; and the practices are key aspects of the sound instruction of poor and minority children. Teachers stated that teacher education programs did not prepare them to teach these students and that they had to learn this on the job.     

An Exploratory Analysis of Differential Item Functioning and Its Possible Sources in a Higher Education Admissions Context

We analyzed a pool of items from an admissions test for differential item functioning (DIF) for groups based on age, socioeconomic status, citizenship, or English language status using Mantel-Haenszel and item response theory. DIF items were systematically examined to identify its possible sources by item type, content, and wording. DIF was primarily found in the citizenship group. As suggested by expert reviewers, possible sources of DIF in the direction of U.S. citizens was often in Quantitative Reasoning in items containing figures, charts, tables depicting real-world (as opposed to abstract) contexts. DIF items in the direction of non-U.S. citizens included “mathematical” items containing few words. DIF for the Verbal Reasoning items included geocultural references and proper names that may be differentially familiar for non-U.S. citizens. This study is responsive to foundational changes in the fairness section of the Standards for Educational and Psychological Testing, which now consider additional groups in sensitivity analyses, given the increasing demographic diversity in test-taker populations.     

American Education—A Scapegoat

ABSTRACT

An essay's motive or research problem consists of the rhetorical moves illuminating why that essay matters—what puzzling elements of a primary source it resolves, which contradictions in the data it explains, or what gaps in the literature it fills. This article invites college instructors to dedicate some of their classroom time to teaching students how to construct original, motive-driven arguments. More specifically, the article describes the conceptual triangle technique that uses a simple three-point concept map as the first step in active argument building. This technique is simple and flexible enough to be adapted across subject areas, data, and disciplines. The focus on scholarly motive in general and the use of the conceptual triangle in particular can be effective ways to help academic writers at all levels to develop original arguments that matter.