Coplanar electrowetting-induced stirring as a tool to manipulate biological samples in lubricated digital microfluidics. Impact of ambient phase on drop internal flow pattern     

Laurent Davoust  Yves Fouillet  Rachid Malk  Johannes Theisen 《Biomicrofluidics》2013,7(4)

Oscillating electrowetting on dielectrics (EWOD) with coplanar electrodes is investigated in this paper as a way to provide efficient stirring within a drop with biological content. A supporting model inspired from Ko et al. [Appl. Phys. Lett. 94, 194102 (2009)] is proposed allowing to interpret oscillating EWOD-induced drop internal flow as the result of a current streaming along the drop surface deformed by capillary waves. Current streaming behaves essentially as a surface flow generator and the momentum it sustains within the (viscous) drop is even more significant as the surface to volume ratio is small. With the circular electrode pair considered in this paper, oscillating EWOD sustains toroidal vortical flows when the experiments are conducted with aqueous drops in air as ambient phase. But when oil is used as ambient phase, it is demonstrated that the presence of an electrode gap is responsible for a change in drop shape: a pinch-off at the electrode gap yields a peanut-shaped drop and a symmetry break-up of the EWOD-induced flow pattern. Viscosity of oil is also responsible for promoting an efficient damping of the capillary waves which populate the surface of the actuated drop. As a result, the capillary network switches from one standing wave to two superimposed traveling waves of different mechanical energy, provided that actuation frequency is large enough, for instance, as large as the one commonly used in electrowetting applications (f ∼ 500 Hz and beyond). Special emphasis is put on stirring of biological samples. As a typical application, it is demonstrated how beads or cell clusters can be focused under flow either at mid-height of the drop or near the wetting plane, depending on how the nature of the capillary waves is (standing or traveling), and therefore, depending on the actuation frequency (150 Hz–1 KHz).  相似文献   

Education in modern Egypt     

M. K. Harby  M. El -Hadi Affifi 《International Review of Education/Internationale Zeitschrift für Erziehungswissenschaft/Revue internationale l'éducation》1958,4(1):423-439

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Problem‐based learning benefits for basic sciences education     

Amal A. El‐Moamly M.D.  Ph.D. 《Anatomical sciences education》2008,1(4):189-190

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Factors Influencing Schoolchildren's Responses to a Questionnaire in Wildlife Conservation Education     

Jean-Marie Ballouard  Stephen J. Mullin  Rastko Ajtic  José Carlos Brito  El Hassan ElMouden  Mehmet Erdogan 《International Journal of Science Education》2013,35(3):469-483

Questionnaires are important tools for assessing attitudes regarding conservation issues. However, they are not easily comparable and their reliability has been insufficiently assessed. We examined factors influencing responses to open- and closed-ended questions about animal conservation to more than 600 schoolchildren (9 years old on average). We analysed the level of understanding, controllable (e.g. sample size) and less controllable factors (e.g. affectivity). Most children responded appropriately to the questions, but subtle changes in the phrasing influenced the answers. Affectivity towards endearing species and spontaneity also influenced the responses whereas small sample sizes (～50 children) provided relatively stable patterns. Overall, we suggest that standardization of questionnaires administered over large spatial and time scales is needed to accurately assess children's attitudes towards conservation issues.  相似文献   

Perceptions of the Nature and ‘Goodness’ of Argument among College Students,Science Teachers,and Scientists     

Issam Abi‐El‐Mona 《International Journal of Science Education》2013,35(4):573-605

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Egg-laying preference for ethanol involving learning has adaptive significance inDrosophila melanogaster     

N. Cadieu  L. El Ghadraoui  J. -C. Cadieu 《Learning & behavior》2000,28(2):187-194

To study the influence of negative or positive experience of the ingestion of ethanol in femaleDrosophila with thefast form of the Adh gene on the acceptance of a medium containing this substance as site for egg laying, flies raised on a medium without alcohol were kept (1) on a regular medium, (2) on a medium supplemented with ethanol, (3) on a medium supplemented with 4-methylpyrazole (4-MP, an inhibitor of the enzyme ADH), and (4) on a medium containing both ethanol and this inhibitor. Whereas theDrosophila exhibited no spontaneous egg-laying preference for ethanol, a preference was induced by the ingestion of this substance, which also led to an increase in the number of eggs laid. By contrast, ingestion of ethanol, associated with the inhibitor, reduced the number of eggs laid and led to an avoidance of ethanol-containing media. Flies treated with ethanol and 4-MP exhibited signs of sickness (reduction in locomotor activity and loss of balance). The egg-laying preference for the ethanol results from learning linked to the metabolic utilization of this alcohol. The adaptative significance of this learning is discussed.  相似文献   

Recent trends and developments in primary and secondary education in the Arab world     

Abdel A. H. El Koussy 《International Review of Education/Internationale Zeitschrift für Erziehungswissenschaft/Revue internationale l'éducation》1967,13(2):198-211

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Instrumentalism revitalized     

El Mawas  Omar 《Metascience》2020,29(1):41-45

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Bridging identities through religious television contents: Javanese female descendants,Islamic viewing and Malay identity projection     

Lily El Ferawati Rofil  Md Azalanshah Md Syed  Azizah Hamzah 《亚洲交流杂志》2016,26(1):42-57

This study explores the uses of Islamic television content in bridging the gap between Javanese and Malay identity among the Malay women of Javanese descent in Malaysia. Malaysian religious television programmes have constantly promoted the Islamic identifications of Malayness, enabling the Malay audience to reconstruct the culturally religious identity. While the reconstruction of Islamic identity through television viewing simply represents a lived experience for the majority of the Malay society, it has some cultural meanings for certain Malay sub-ethnic communities, such as the Javanese. This ethnographic study on a Malaysian Javanese community reveals that the interpretive engagement of this particular community in Islamic television viewing serves the purpose of negotiating Malay identity. The results of this study suggest that religious content can serve as an engaging platform to construct multi-ethnic identities beside popular and ethnic-related contents.  相似文献   

Dialed In: Continuous Response Measures in Televised Political Debates and Their Effect on Viewers     

Jeremy Saks  Jordan L. Compton  Ashley Hopkins  Kareem El Damanhoury 《广播与电子媒介杂志》2016,60(2):231-247

As a result of emerging debate formats and technological advancements over the years, the media started using continuous response measures (CRMs) in the form of on-screen trackers, allowing select audiences to rate candidate performances in political debates in 2004. Given the limited amount of scholarly research that has tackled this issue, this study aims to investigate the effect of CRMs on college students’ voting choices and perceptions of political candidates. This experimental study has found that these trackers did influence the participants’ evaluations of the political candidates shown in the debate regardless of previously stated political affiliation.  相似文献