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H. A. Guidobaldi Y. Jeyaram C. A. Condat M. Oviedo I. Berdakin V. V. Moshchalkov L. C. Giojalas A. V. Silhanek V. I. Marconi 《Biomicrofluidics》2015,9(2)
Many self-propelled microorganisms are attracted to surfaces. This makes their dynamics in restricted geometries very different from that observed in the bulk. Swimming along walls is beneficial for directing and sorting cells, but may be detrimental if homogeneous populations are desired, such as in counting microchambers. In this work, we characterize the motion of human sperm cells ∼60 μm long, strongly confined to ∼25 μm shallow chambers. We investigate the nature of the cell trajectories between the confining surfaces and their accumulation near the borders. Observed cell trajectories are composed of a succession of quasi-circular and quasi-linear segments. This suggests that the cells follow a path of intermittent trappings near the top and bottom surfaces separated by stretches of quasi-free motion in between the two surfaces, as confirmed by depth resolved confocal microscopy studies. We show that the introduction of artificial petal-shaped corrugation in the lateral boundaries removes the tendency of cells to accumulate near the borders, an effect which we hypothesize may be valuable for microfluidic applications in biomedicine. 相似文献
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Pittman Ramona T. Lindner Amanda L. Zhang Shuai Binks-Cantrell Emily Malatesha Joshi R. 《Reading and writing》2022,35(9):2075-2076
Reading and Writing - 相似文献
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Pittman Ramona T. Lindner Amanda L. Zhang Shuai Binks-Cantrell Emily Malatesha Joshi R. 《Reading and writing》2022,35(9):2049-2074
Reading and Writing - Teachers’ knowledge of literacy has gained considerable interest over the last three.decades, largely with a focus on the basic language constructs of phonological.... 相似文献
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Ramona E. Archer-Bradshaw 《Research in Science Education》2017,47(1):67-93
This study examined the extent to which the instructional practices of science teachers in Barbados are congruent with best practices for teaching for scientific literacy. Additionally, through observation of practice, it sought to determine the teachers’ demonstrated role in the classroom, their demonstration of learning through discourse, learning goals and the nature of classroom activities. Five hundred nineteen students from 12 of the 23 secondary schools on the island and 15 teachers across 8 schools participated in the study. Data were collected by means of a questionnaire, an observational schedule and field notes. It was found that while problem-solving and questioning were mainly used in the classroom, the use of experiments was among the least popular teaching strategies. Additionally, results showed that teachers’ display of the knowledge of the characteristics of scientific literacy was unsatisfactory. Generally, the findings indicate a gap between teaching for scientific literacy as expressed in the literature and current instructional practices in secondary science classrooms in Barbados. 相似文献
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Narissra M. Punyanunt-Carter Marilda J. Oviedo Samer Melhem 《Qualitative Research Reports in Communication》2019,20(1):67-74
Based on questionnaire responses from 381 undergraduate students, this study sought to examine perceptions of Hispanics on television. Results revealed that college students perceive Hispanics portrayals on television are mainly stereotypical and often highlight negative perceptions (e.g., lazy and ill-tempered). Students regarded Hispanics to be hardworking and to prioritize culture. Perceptions of Hispanic men were mainly controlling figures and Hispanic women were mostly caretaking characters. These findings suggest that television can affect the way college students view and possibly communicate with Hispanics. 相似文献
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Ramona Fruja Amthor Kevin Roxas 《Educational Studies A Journal of the American Educational Studies Association》2016,52(2):155-176
In this article, we draw attention to the discourses and practices of multicultural and culturally relevant education as curricular contexts with long-lasting implications for newcomer youth. To best serve immigrant and refugee students and more explicitly include them in the field's discourse, we argue for a conceptual move to widen the scope of multicultural education and culturally relevant pedagogy. We highlight the tremendous contributions multicultural education approaches have made to equitable education, while also examining the ways in which some of their widespread theoretical framing have yet to address the particular needs of immigrant and refugee youth. We then suggest conceptual shifts to widen their scope to include newcomer youth's varied experiences and identity positions. These shifts are (a) advancing the role of genuine cross-cultural relationships over traditional forms of cross-cultural competence in multicultural educational spaces and (b) abdicating the search for cultural authenticity implied in some multicultural education practice in favor of facilitating cultural agency for newcomer youth. 相似文献
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The influence of locus of control, diagnosis, and remediation on immediate and retained achievement and attitudes of middle school science students was the focus of this study. Subjects in the experiment were assessed for locus of control and experienced one of three treatments: no diagnosis or remediation; diagnosis with no remediation; or, diagnosis and remediation. Immediate achievement was measured at two points during the experiment, and retention was measured 30 days following the experiment. Diagnosis and remediation proved to be significantly effective in increasing retained achievement. Internal locus of control subjects out-scored external subjects in the areas of both immediate and retained achievement. Whites achieved higher than blacks in retention. Attitudes of all groups tended to be positive. These findings suggest that diagnostic or diagnostic and remedial instruction is an effective means of increasing the retention level of middle school students. 相似文献