Flow of DNA solutions in a microfluidic gradual contraction     

Shelly Gulati  Susan J. Muller  Dorian Liepmann 《Biomicrofluidics》2015,9(5)

The flow of λ-DNA solutions in a gradual micro-contraction was investigated using direct measurement techniques. The effects on DNA transport in microscale flows are significant because the flow behavior is influenced by macromolecular conformations, both viscous and elastic forces dominate inertial forces at this length scale, and the fully extended length of the molecule approaches the characteristic channel length w_c (L/w_c ∼ 0.13). This study examines the flow of semi-dilute and entangled DNA solutions in a gradual planar micro-contraction for low Reynolds numbers (3.7 × 10⁻⁶< Re < 3.1 × 10⁻¹) and high Weissenberg numbers (0.4 < Wi < 446). The semi-dilute DNA solutions have modest elasticity number, El = Wi/Re = 55, and do not exhibit viscoelastic behavior. For the entangled DNA solutions, we access high elasticity numbers (7.9 × 10³< El < 6.0 × 10⁵). Video microscopy and streak images of entangled DNA solution flow reveal highly elastic behavior evidenced by the presence of large, stable vortices symmetric about the centerline and upstream of the channel entrance. Micro-particle image velocimetry measurements are used to obtain high resolution, quantitative velocity measurements of the vortex growth in this micro-contraction flow. These direct measurements provide a deeper understanding of the underlying physics of macromolecular transport in microfluidic flow, which will enable the realization of enhanced designs of lab-on-a-chip systems.  相似文献   

Education through activities: Three viewpoints     

Marie Reynolds Rodgers 《Peabody Journal of Education》2013,88(5):304-308

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The Story of Joseph     

Marie Rodgers 《The Educational forum》2013,77(2)

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Associations between maternal childhood maltreatment and psychopathology and aggression during pregnancy and postpartum     

Lang AJ  Rodgers CS  Lebeck MM 《Child abuse & neglect》2006,30(1):17-25

OBJECTIVE: This study examines the association between maternal childhood maltreatment and psychopathology and aggression in intimate relationships during pregnancy and the postpartum period. METHOD: Forty-four pregnant women who were recruited from an obstetric clinic and local advertising periodical completed questionnaires about childhood maltreatment and psychopathology during their first trimester of pregnancy. Approximately 1 year after the birth of the child, 32 of the original participants completed these same questionnaires. Regression models were used to test the relationship between childhood maltreatment and psychopathology and aggression during pregnancy and 1 year postpartum. RESULTS: Sexual abuse and emotional neglect were related to psychopathology during pregnancy, and emotional neglect and physical abuse and neglect predicted poorer maternal outcomes 1 year postpartum. Contrary to expectations, physical abuse was related to less aggression during pregnancy, and emotional abuse was associated with less pathology postpartum. CONCLUSIONS: The results of this study indicate that childhood maltreatment is associated with poorer maternal mental health during pregnancy and 1 year postpartum and points to the need to improve targeting and treatment of psychopathology during this time.  相似文献   

In practice: Peer mentors: Helping bridge the advising gap     

Kimmo I. Rosenthal  Shelly H. Shinebarger 《About Campus》2010,15(1):24-27

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Social constructivism and the <Emphasis Type="Italic">Believing Game</Emphasis>: a mathematics teacher’s practice and its implications     

Shelly Sheats Harkness 《Educational Studies in Mathematics》2009,70(3):243-258

The study reported here is the third in a series of research articles (Harkness, S. S., D’Ambrosio, B., & Morrone, A. S.,in Educational Studies in Mathematics 65:235–254, 2007; Morrone, A. S., Harkness, S. S., D’Ambrosio, B., & Caulfield, R. in Educational Studies in Mathematics 56:19–38, 2004) about the teaching practices of the same university professor and the mathematics course, Problem Solving, she taught for preservice elementary teachers. The preservice teachers in Problem Solving reported that they were motivated and that Sheila made learning goals salient. For the present study, additional data were collected and analyzed within a qualitative methodology and emergent conceptual framework, not within a motivation goal theory framework as in the two previous studies. This paper explores how Sheila’s “trying to believe,” rather than a focus on “doubting” (Elbow, P., Embracing contraries, Oxford University Press, New York, 1986), played out in her practice and the implications it had for both classroom conversations about mathematics and her own mathematical thinking.  相似文献   

Cross-validation of the revised motivation for physical activity measure in active women     

Wilson PM  Rodgers WM  Fraser SN 《Research quarterly for exercise and sport》2002,73(4):471-477

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Exploring the influence of course elements and emotional connection to content on students’ approaches to learning in an introductory food science and human nutrition course     

Shelly J. Schmidt 《Journal of Food Science Education》2020,19(2):59-73

Researchers have identified three approaches to learning—surface, strategic, and deep. These approaches are influenced by various contextual and student factors, including teaching methods, assessments, and relevance to future career. The global objective of this study was to explore the influence of course elements and students’ emotional connection to section content on students’ approaches to learning in an introductory Food Science and Human Nutrition course. Students completed two questionnaires for the Nutrition and Health (NH) and Composition and Chemistry (CC) course sections: (a) Entwistle's ASSIST Inventory and (b) a questionnaire developed to assess students’ perceived usefulness of assignments, learning resources, and emotional connection to section content. Students’ approaches to learning did not significantly differ between NH and CC sections, with the majority reporting use of strategic or deep approaches. Generally, positive correlations were obtained for learners who used the deep and strategic approaches and their perceived usefulness of assignments and learning resources. In stark contrast, negative correlations were identified for learners who used the surface approach and their perceived usefulness of learning resources and assignments. Regarding emotional connection to section content, compared to learners who used the deep and strategic approaches, learners who used the surface approach did not enjoy and felt anxious about learning the content in both sections. Furthermore, based on regression analysis, the surface learning approach was a predictor for low exam scores in both sections. Based on these findings, instructors should implement practices in course design, instructional methods, and assessment strategies that help students choose deep and strategic approaches to learning, while minimizing surface approaches.  相似文献   

The Universal and the unique in dyslexia: A cross-linguistic investigation of reading and reading fluency in Hebrew-and English-speaking children with reading disorders     

Tami Katzir  Shelly Shaul  Zvia Breznitz  Maryanne Wolf 《Reading and writing》2004,17(7-8):739-768

Cross-linguistic studies provide a unique tool for the identification of universal processes in oral and written language, both in development and in breakdown (Annual Review of psychology, 52, 369–396). Examining the differential strengths and weaknesses of children with dyslexia in contrasting orthographies can help illumine both the more universal aspects of reading disabilities, as well as their individual language-specific attributes. The aim of this study, was to investigate the shared and distinctive characteristics of readers with dyslexia on reading and reading fluency across Hebrew and English orthographies. Differences between 60 Hebrew and English-speaking children with dyslexia on a battery of cognitive, linguistic, and reading measures will be discussed along with theoretical implications.  相似文献   

GIFTED ADOLESCENTS: AT RISK FOR SUICIDE     

Carolyn Yewchuk  Shelly Jobagy 《High Ability Studies》1991,2(1):73-85

The high rate of suicide among adolescents is an ever present concern to those who work with troubled youth. It has commonly been thought that adolescents of high intellectual ability are sheltered from the everyday stresses that lead their peers to commit suicide. However, researchers are discovering that giftedness carries with it special stresses that may make the gifted adolescent vulnerable to emotional distress, leading to suicidal behaviour. This paper will investigate the exceptional vulnerabilities of the gifted adolescent, and show how the practitioner may recognize the warning signs in this population. In addition, recommendations will be made regarding prevention and intervention strategies.

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