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42.
We have developed a method for studying cellular adhesion by using a custom-designed microfluidic device with parallel non-connected tapered channels. The design enables investigation of cellular responses to a large range of shear stress (ratio of 25) with a single input flow-rate. For each shear stress, a large number of cells are analyzed (500–1500 cells), providing statistically relevant data within a single experiment. Besides adhesion strength measurements, the microsystem presented in this paper enables in-depth analysis of cell detachment kinetics by real-time videomicroscopy. It offers the possibility to analyze adhesion-associated processes, such as migration or cell shape change, within the same experiment. To show the versatility of our device, we examined quantitatively cell adhesion by analyzing kinetics, adhesive strength and migration behaviour or cell shape modifications of the unicellular model cell organism Dictyostelium discoideum at 21 °C and of the human breast cancer cell line MDA-MB-231 at 37 °C. For both cell types, we found that the threshold stresses, which are necessary to detach the cells, follow lognormal distributions, and that the detachment process follows first order kinetics. In addition, for particular conditions’ cells are found to exhibit similar adhesion threshold stresses, but very different detachment kinetics, revealing the importance of dynamics analysis to fully describe cell adhesion. With its rapid implementation and potential for parallel sample processing, such microsystem offers a highly controllable platform for exploring cell adhesion characteristics in a large set of environmental conditions and cell types, and could have wide applications across cell biology, tissue engineering, and cell screening.  相似文献   
43.
This article describes the independent study project of a student who was a graduate assistant in a child development laboratory preschool when Hurricanes Katrina and Rita struck the Gulf Coast area. Through her experiences with “Project Katrina” she deepens her understanding of developmentally appropriate practices as she learns firsthand about the project approach and writing an article for publication in a professional journal.  相似文献   
44.
This paper describes the use of a three-circle Venn diagram as a vehicle for introducing pre-service elementary teachers to pedagogical content knowledge (PCK). Each circle of the diagram represents pedagogy, content and context individually. The overlap of any two circles represents the interaction between the circles. For example, the overlap of pedagogy and context relates to the ways that each of these general topics influences the other. The overlap of all three circles represents a complete lesson that is an integration of the three major components of PCK. The Venn diagram is an easily remembered graphic illustration of PCK that can be useful in planning lessons. The use of this graphic organizer in a science capstone course required of all pre-service elementary teachers is described.  相似文献   
45.
马桶座圈背负着一个不公平的污名,那就是被认为是一般家庭中最脏的物件。但科学家们称,我们的家里其实有更为污秽的地方,有些地方还是最令人意想不到的。你会在马桶座圈上切菜吗?我想基本上所有人都说不会。但或许我们得重新考虑一下了。  相似文献   
46.
Jigsaw puzzles are ubiquitous developmental toys in Western societies, used here to examine the development of metarepresentation. For jigsaw puzzles this entails understanding that individual pieces, when assembled, produce a picture. In Experiment 1, 3- to 5-year-olds (N = 117) completed jigsaw puzzles that were normal, had no picture, or comprised noninterlocking rectangular pieces. Pictorial puzzle completion was associated with mental and graphical metarepresentational task performance. Guide pictures of completed pictorial puzzles were not useful. In Experiment 2, 3- to 4-year-olds (N = 52) completed a simplified task, to choose the correct final piece. Guide-use associated with age and specifically graphical metarepresentation performance. We conclude that the pragmatically natural measure of jigsaw puzzle completion ability demonstrates general and pictorial metarepresentational development at 4 years.  相似文献   
47.
This article offers an invitational model for overcoming prejudices. The proposed model is based on Haberman's (1994) five-step approach to facing prejudices, which includes (1) analyzing prejudices; (2) seeking the sources of the beliefs; (3) examining the benefits of prejudice; (4) considering the effects of prejudices; and (5) planning to eliminate prejudices. Purkey's (1992) five-level conflict-management process adapted to prejudice serves as the five-part action plan in Haberman's fifth step. The combination of these two models yields an invitational approach with five parts: (1) perceiving concern, (2) conferring with oneself; (3) consulting with colleagues; (4) confronting the crisis; and (5) combating prejudices. Practical questions and examples are provided to clarify each step. We shall overcome, We shall overcome, We shall overcome someday. If in our hearts we do believe, We shall overcome someday.  相似文献   
48.
This study focuses on the college application behaviors of students from various racial/ethnic groups in order to understand differences in access and college choice. Student characteristics, predispositions, academic abilities, and income levels were taken into account in our analyses. We analyzed data from the National Education Longitudinal Study (NELS) and the Beginning Postsecondary Student Longitudinal Study (BPS) and found significant group differences in preparation behaviors, college application behavior (number of colleges to which students applied), and attendance at their first choice of institution. The results of this study call attention to the need for campuses to evaluate the potential effects of policy decisions that may impact student choice for different populations of students.  相似文献   
49.
Studies using three koi (Cyprinus carpio) investigated discrimination of musical stimuli. The common protocol used a single manipulandum and a multiple continuous reinforcement-extinction schedule signaled by music of the S+ and S− types in 30-sec presentations separated by a silent 15-sec intertrial interval. In a categorization study, the fish learned to discriminate blues recordings from classical, generalizing from John Lee Hooker (guitar and vocals) and Bach (oboe concertos) to multiple artists and ensembles. A control-by-reversal test developed into a demonstration of progressive improvement in iterated reversal learning. The subjects next learned to discriminate single-timbre synthesized versions of similar music. In the final study, which used melodies with the same order of note-duration values, but with mirror-image orders of pitch values, one fish discriminated melodies with no timbre cues, in contrast to results reported in rats.  相似文献   
50.
This study investigated how an authentic assessment program was used to examine student learning outcomes within the context of a Christian university’s institutional mission, core values, and distinctive qualities. For the purposes of this study, an authentic assessment program is defined as assessing student-produced work within the context of the institutional mission. A sample of 1,814 undergraduate students taking one or more general education courses at the university during the 2007–2009 academic years was examined for any significant differences in student learning outcomes. A univariate analysis of covariance (ANCOVA) indicated the Student Assessment System (SAS) scores for the online students were not significantly different from the SAS scores for the face-to-face (F2F) students after controlling for course grade. These results suggest that online students achieved the same critical mission-related educational outcomes that the university required of its F2F students. An implication of this finding is that the university just as effectively articulated its faith-based mission and vision to the online students as it did to its students taking classes F2F.  相似文献   
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