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151.
Orloff ND Dennis JR Cecchini M Schonbrun E Rocas E Wang Y Novotny D Simmonds RW Moreland J Takeuchi I Booth JC 《Biomicrofluidics》2011,5(4):44107-441079
We present a 91 MHz surface acoustic wave resonator with integrated microfluidics that includes a flow focus, an expansion region, and a binning region in order to manipulate particle trajectories. We demonstrate the ability to change the position of the acoustic nodes by varying the electronic phase of one of the transducers relative to the other in a pseudo-static manner. The measurements were performed at room temperature with 3 μm diameter latex beads dispersed in a water-based solution. We demonstrate the dependence of nodal position on pseudo-static phase and show simultaneous control of 9 bead streams with spatial control of −0.058 μm/deg ± 0.001 μm/deg. As a consequence of changing the position of bead streams perpendicular to their flow direction, we also show that the integrated acoustic-microfluidic device can be used to change the trajectory of a bead stream towards a selected bin with an angular control of 0.008 deg/deg ± 0.000(2) deg/deg. 相似文献
152.
Giraud G Pethig R Schulze H Henihan G Terry JG Menachery A Ciani I Corrigan D Campbell CJ Mount AR Ghazal P Walton AJ Crain J Bachmann TT 《Biomicrofluidics》2011,5(2):24116
The manipulation of ribosomal RNA (rRNA) extracted from E. coli cells by dielectrophoresis (DEP) has been demonstrated over the range of 3 kHz-50 MHz using interdigitated microelectrodes. Quantitative measurement using total internal reflection fluorescence microscopy of the time dependent collection indicated a positive DEP response characterized by a plateau between 3 kHz and 1 MHz followed by a decrease in response at higher frequencies. Negative DEP was observed above 9 MHz. The positive DEP response below 1 MHz is described by the Clausius-Mossotti model and corresponds to an induced dipole moment of 3300 D with a polarizability of 7.8×10(-32) F m(2). The negative DEP response above 9 MHz indicates that the rRNA molecules exhibit a net moment of -250 D, to give an effective permittivity value of 78.5 ε(0), close to that of the aqueous suspending medium, and a relatively small surface conductance value of ~0.1 nS. This suggests that our rRNA samples have a fairly open structure accessible to the surrounding water molecules, with counterions strongly bound to the charged phosphate groups in the rRNA backbone. These results are the first demonstration of DEP for fast capture and release of rRNA units, opening new opportunities for rRNA-based biosensing devices. 相似文献
153.
Grace M. Jackson-Brown 《The Reference Librarian》2017,58(2):136-151
This study is an exploratory qualitative investigation of academic library blogs with the purpose of examining how the technology of blogging is evolving for reference and research purposes at particular academic law libraries. This study uses anthropological archive research methods to study the blogs’ posts and triangulates the study with librarian blogger interviews. It provides a look into possible future directions for blogging in academic law libraries that may serve as a model for other academic libraries. 相似文献
154.
Ninger Zhou Nielsen L. Pereira Tarun Thomas George Jeffrey Alperovich Joran Booth Senthil Chandrasegaran Jeffrey David Tew Devadatta M. Kulkarni Karthik Ramani 《Journal of Science Education and Technology》2017,26(5):481-493
The societal demand for inspiring and engaging science, technology, engineering, and mathematics (STEM) students and preparing our workforce for the emerging creative economy has necessitated developing students’ self-efficacy and understanding of engineering design processes from as early as elementary school levels. Hands-on engineering design activities have shown the potential to promote middle school students’ self-efficacy and understanding of engineering design processes. However, traditional classrooms often lack hands-on engineering design experiences, leaving students unprepared to solve real-world design problems. In this study, we introduce the framework of a toy design workshop and investigate the influence of the workshop activities on students’ understanding of and self-efficacy beliefs in engineering design. Using a mixed method approach, we conducted quantitative analyses to show changes in students’ engineering design self-efficacy and qualitative analyses to identify students’ understanding of the engineering design processes. Findings show that among the 24 participants, there is a significant increase in students’ self-efficacy beliefs after attending the workshop. We also identified major themes such as design goals and prototyping in students’ understanding of engineering design processes. This research provides insights into the key elements of middle school students’ engineering design learning and the benefits of engaging middle school students in hands-on toy design workshops. 相似文献
155.
156.
Amy E. Booth 《Child development》2009,80(4):1243-1250
What factors determine whether a young child will learn a new word? Although there are surely numerous contributors, the current investigation highlights the role of causal information. Three‐year‐old children (N = 36) were taught 6 new words for unfamiliar objects or animals. Items were described in terms of their causal or noncausal properties. When tested only minutes after training, no significant differences between the conditions were evident. However, when tested several days after training, children performed better on words trained in the causal condition. These results demonstrate that the well‐documented effect of causal information on learning and categorization extends to word learning in young children. 相似文献
157.
158.
ABSTRACTScholars writing on agency argue that normally, individuals who experience social structures as comfortable will tend to want to reproduce them while those who experience these structures as oppressive will want to change them. This is a bleak outlook because it suggests that those in positions of power and influence are less likely to seek to overhaul the very system of rewards and punishments that benefits them. However, there are exceptions to this pattern: instances where those who experience the structures as comfortable, nevertheless, work at transforming them. This article introduces an alternative perspective to current transformation discourses by seeking to understand why such exceptions exist. It argues that critical engagement is an important dimension of such transformation, and examines how it interacts with reflexivity to shape individual choices and reformulate interest. Drawing on a hermeneutic phenomenological analysis of in-depth interviews with 10 academics who have been identified as agents of change at one university in South Africa, we reveal how individuals are able to shift their understanding of what is or is not in their interest in a context where raced, gendered and classed interests are deeply embedded in the fabric of the society. In such contexts, reflexivity and critical personal engagement with one’s context can lead to a shift in interest and then consciousness as the individual comes to see and experience things from a different vantage point, opening up the possibility for a changed relationship with the social structure and its constraints and determining influence. 相似文献
159.
Michael Windle Carol Miller-Tutzauer Grace M. Barnes John Welte 《Child development》1991,62(1):179-189
Adolescent perceptions of help-seeking social resources (e.g., parents, friends, school counselor, clergyman) they would utilize if they were having substance abuse difficulties were investigated for samples of early and middle adolescents. 8 different perceived help-seeking categories were identified, and intergroup comparisons were made with regard to gender and ethnic/racial group and with regard to alcohol consumption, substance-related problems, and school misconduct. 2 perceived help-seeking categories had the highest levels of problem behaviors. The first category consisted of adolescents who identified friends as the only social resource they would utilize if they were having substance abuse problems. The second category, referred to as social isolates, indicated that they would not utilize any social resource if they were having substance abuse problems. There were approximately twice as many male social isolates as female social isolates, and blacks and Hispanics were highly overrepresented in the social isolate category. 相似文献
160.
OBJECTIVE: It has often been hypothesized that because of a lack of early satisfactory attachments, sex offenders grow up unable to form relationships with adults, which makes them susceptible to pursue intimacy in maladaptive ways. This research aims to empirically examine the parental bonding patterns for a group of sex offenders, comparing child molesters and rapists. METHOD: Seventy-six men convicted of a sexual offense (57 child molesters and 19 rapists) completed the parental bonding instrument (PBI), and were assessed by means of a semi-structured clinical interview. RESULTS: Affectionless control style of parental bonding was highly prevalent amongst the sex offenders. There was some suggestion that low parental care was associated with childhood abuse and disturbances, particularly for child molesters. High overprotection in mothers was linked with parental separation and sex play with male peers in childhood. CONCLUSIONS: There is a need to replicate the study with non-sexual offenders as a comparison group, and to establish whether the PBI provides a useful adjunct to studies of adult romantic attachment in sex offenders. 相似文献