13,126 research outputs found

    Unsteady separation past moving surfaces

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    Unsteady boundary-layer development over moving walls in the limit of infinite Reynolds number is investigated using both the Eulerian and Lagrangian formulations. To illustrate general trends, two model problems are considered, namely the translating and rotating circular cylinder and a vortex convected in a uniform flow above an infinite flat plate. To enhance computational speed and accuracy for the Lagrangian formulation, a remeshing algorithm is developed. The calculated results show that unsteady separation is delayed with increasing wall speed and is eventually suppressed when the speed of the separation singularity approaches that of the local mainstream velocity. This suppression is also described analytically. Only 'upstream-slipping' separation is found to occur in the model problems. The changes in the topological features of the flow just prior to the separation that occur with increasing wall speed are discussed

    The structure of a three-dimensional turbulent boundary layer

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    The three-dimensional turbulent boundary layer is shown to have a self-consistent two-layer asymptotic structure in the limit of large Reynolds number. In a streamline coordinate system, the streamwise velocity distribution is similar to that in two-dimensional flows, having a defect-function form in the outer layer which is adjusted to zero at the wall through an inner wall layer. An asymptotic expansion accurate to two orders is required for the cross-stream velocity which is shown to exhibit a logarithmic form in the overlap region. The inner wall-layer flow is collateral to leading order but the influence of the pressure gradient, at large but finite Reynolds numbers, is not negligible and can cause substantial skewing of the velocity profile near the wall. Conditions under which the boundary layer achieves self-similarity and the governing set of ordinary differential equations for the outer layer are derived. The calculated solution of these equations is matched asymptotically to an inner wall-layer solution and the composite profiles so formed describe the flow throughout the entire boundary layer. The effects of Reynolds number and cross-stream pressure gradient on the cross-stream velocity profile are discussed and it is shown that the location of the maximum cross-stream velocity is within the overlap region

    Arena

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    Newsletter of the Boston University School of Medicine, Student American Medical Association (SAMA

    Curriculum Enhancement for Biology at Purnell Swett High School: A Service-Learning Project

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    For my project, I present my biology service-learning experience at Purnell Swett, a local high school in Pembroke’s community. The major task of this project is providing an educational and positive learning experience of biology and science for tenth-grade students, who are preparing to take the state-mandated End of Course Test (EOCT) for biology. I demonstrate the impact of tutoring and review sessions each week for tenth-grade students currently in biology classes, particularly for students struggling to understand main concepts, while incorporating hands-on experiments and activities within the community to further their biological understanding. The overall goal of my project is to encourage local high school students to continue pursuing a higher education, as well as helping them feel prepared for the biology End of Course Test. My project will also provide an example of how service-learning can be incorporated into any subject, and the positive effect of service-learning within a community

    On the care and feeding of animals

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    The following work contains narratives from characters who are experiencing isolation and loneliness in settings that are mysterious and, at times, terrifying

    Using embedded computer-assisted instruction to teach science to students with Autism Spectrum Disorders

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    The need for promoting scientific literacy for all students has been the focus of recent education reform resulting in the rise of the Science Technology, Engineering, and Mathematics movement. For students with Autism Spectrum Disorders and intellectual disability, this need for scientific literacy is further complicated by the need for individualized instruction that is often required to teach new skills, especially when those skills are academic in nature. In order to address this need for specialized instruction, as well as scientific literacy, this study investigated the effects of embedded computer-assisted instruction to teach science terms and application of those terms to three middle school students with autism and intellectual disability. This study was implemented within an inclusive science classroom setting. A multiple probe across participants research design was used to examine the effectiveness of the intervention. Results of this study showed a functional relationship between the number of correct responses made during probe sessions and introduction of the intervention. Additionally, all three participants maintained the acquired science terms and applications over time and generalized these skills across materials and settings. The findings of this study suggest several implications for practice within inclusive settings and provide suggestions for future research investigating the effectiveness of computer-assisted instruction to teach academic skills to students with Autism Spectrum Disorders and intellectual disability

    Hormone status and measures of joint laxity

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    "This study examined the relationships between oral contraceptive pill (OCP) use and measures of joint laxity. Methods: A menstrual history questionnaire identified 33 female athletes using OCPs. Separate stepwise linear regressions examined the extent to which OCP dosage (estradiol, progesterone) and SHBG% predicted measures of anterior knee laxity, general joint laxity and genu recurvatum. Secondary regression analyses examined the relationship between duration of OCP use and each joint laxity measure. Results: OCP dosage and %SHBG binding affinity were not predictors of joint laxity. Greater duration of OCP use positively predicted greater genu recurvatum (R2 = 20.8%, P=0.008). Conclusions: While the variations in dosages of common OCPs were not found to influence measures of joint laxity, prolonged exposure to these synthetic hormones may increase genu recurvatum over time. Further work is needed to clarify the effects of OCPs on joint laxity, a potential risk factor for knee injury."--Abstract from author supplied metadata

    Konnecting Kindergarten with the PreK Kurriculum

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    Kindermusik, a relatively new music program for the very young, translated from German, emphasizes the total development of children, which is very similar to the overall efforts of a preschool curriculum. In the following project, a thorough integration of the two curricula will be attempted
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