1,842 research outputs found

    Financial Exigency: Need It Affect the Quality of Biology Curricula?

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    Declining enrollments and financial restraints require that science departments seek ways to meet academic commitments within the framework of reduced budgets and faculty resources without sacrificing quality programs. The following describes our evaluation of the role of the laboratory in the undergraduate biology curriculum and the positive effects achieved on our academic, financial, and faculty resources by separating labs from lecture courses and reducing the number of labs required for majors and nonmajors. Several years ago we experienced increased enrollments coupled with only modest increases in funds to deliver our undergraduate instructional programs. To resolve this problem we developed a new approach to the role of lecture and laboratory courses for our biology majors, the nonmajor, and the students in the allied health programs serviced by our department. The changes effected by us then would appear to be equally appropriate in today\u27s economy when inflationary pressures and a decline in students make it imperative that departments look to ways to meet their academic commitments within the framework of declining budgets and faculty resources

    Effects of Cross-Sectional Shape, Solidity, and Distribution of Heat-Transfer Coefficient on the Torsional Stiffness of Thin Wings Subjected to Aerodynamic Heating

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    A study has been made of the effects of varying the shape, solidity, and heat-transfer coefficient of thin wings with regard to their influence on the torsional-stiffness reduction induced by aerodynamic heating. The variations in airfoil shape include blunting, flattening, and combined blunting and flattening of a solid wing of symmetrical double-wedge cross section. Hollow double-wedge wings of constant skin thickness with and without internal webs also are considered. The effects of heat-transfer coefficients appropriate for laminar and turbulent flow are investigated in addition to a step transition along the chord from a lower to a higher constant value of heat-transfer coefficient. From the results given it is concluded that the flattening of a solid double wedge decreases the reduction in torsional stiffness while slight degrees of blunting increase the loss. The influence of chordwise variations in heat-transfer coefficient due to turbulent and laminar boundary-layer flow on the torsional stiffness of solid wings is negligible. The effect of a step transition in heat-transfer coefficient along the chord of a solid wing can, however, become appreciable. The torsional-stiffness reduction of multiweb and hollow double-wedge wings is substantially less than that calculated for a solid wing subjected to the same heating conditions

    Cross-Sectional Deformations of Monocoque Beams and Their Effects on the Natural Vibration Frequencies

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    The variational principle, differential equations, and boundary conditions governing the cross-sectional distortions due to inertia loading of a two-dimensional model of a thin monocoque wing are shown. A theoretical analysis of this simplified model is made in order to determine the nature of the coupling between the cross-sectional modes and the spanwise deformation modes. General solutions are obtained in finite-difference form for arbitrary cross sections and an exact solution is presented for a parabolic-arc cross section of constant cover thickness. The application of these results in evaluating the coupled frequencies of the actual structure is discussed. Frequencies evaluated for a parabolic-arc monocoque beam show good agreement with experimental values

    Effect of transient heating on vibration frequencies of some simple wing structures

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    Thermal stresses, which may result from transient heating, can cause changes in the effective stiffness of wing structures. Some effects of this change in stiffness were investigated experimentally by radiantly heating three types of simple wing structures: a uniform plate, a solid double-wedge section, and a circular-arc multiweb-wing section. Changes in stiffness were determined by measuring the changes in natural frequency of vibration during transient heating. Some comparisons are made between theoretical calculations and the measured data

    Optimizing astrophotonic spatial reformatters using simulated on-sky performance

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    One of the most useful techniques in astronomical instrumentation is image slicing. It enables a spectrograph to have a more compact angular slit, whilst retaining throughput and increasing resolving power. Astrophotonic components like the photonic lanterns and photonic reformatters can be used to replace bulk optics used so far. This study investigates the performance of such devices using end-to-end simulations to approximate realistic on-sky conditions. It investigates existing components, tries to optimize their performance and aims to understand better how best to design instruments to maximize their performance. This work complements the recent work in the field and provides an estimation for the performance of the new components.Comment: Conference proceedings in SPIE 2018 Austin Texa

    Service Learning and Community Engagement: A Comparison of Three National Contexts

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    One of the presumptions of a well-functioning, viable democracy is that citizens participate in the life of their communities and nation. The role of higher education in forming actively engaged citizens has long been the focus of scholarly research, but recently an active debate has emerged concerning the role of service as a third core function of institutions of higher learning. Service learning (SL), a teaching approach that extends student learning beyond the classroom, is increasingly seen as a vehicle to realize this third core function. By aligning educational objectives with community partners’ needs, community service is meant to enhance, among other objectives, reciprocal learning. Although the term and its associated activities originated in the United States (US), theoretical debates linking civic engagement and education extend far beyond the US context. Nevertheless, research on SL as a distinctive pedagogical approach remains a nascent field. A significant gap exists in the literature about what this pedagogical approach seeks to achieve (in nature and in outcomes) and how it is construed in non-western contexts. Using a comparative analysis across three widely different contexts, this article explores the extent to which these differences are merely differences in degree or whether the differences are substantive enough to demand qualitatively different models for strengthening the relationship between higher education and civil society

    P\u3csup\u3e3\u3c/sup\u3e: Phylogenetic posterior prediction in RevBayes

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    © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. Tests of absolute model fit are crucial in model-based inference because poorly structured models can lead to biased parameter estimates. In Bayesian inference, posterior predictive simulations can be used to test absolute model fit. However, such tests have not been commonly practiced in phylogenetic inference due to a lack of convenient and flexible software. Here, we describe our newly implemented tests of model fit using posterior predictive testing, based on both data- and inference-based test statistics, in the phylogenetics software RevBayes. This new implementation makes a large spectrum of models available for use through a user-friendly and flexible interface
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