969 research outputs found

    Probing the National Geoscience Faculty Survey for Reported Use of Practices that Support Inclusive Learning Environments in Undergraduate Courses

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    What is the extent to which college and university geoscience faculty report using education practices that contribute to more inclusive learning environments and engage a diverse population of students? In the 2016 National Geoscience Faculty Survey, faculty answered questions about their practices in a specific introductory or major course they had taught in the previous two years, and about how they share and learn about the content and methods used in their teaching. Based on factor analysis, 22 of the survey questions divided into four categories associated with inclusive teaching practices: geoscientist representations, curricular choices, learning strategies, and career pathways. The self-reported use of practices across these four categories varies greatly, with some used by as many as 71% of faculty respondents whereas others by only 8%. These data provide new information on the current state of teaching practices in the geosciences with regard to inclusive practices, and establish a baseline to which responses from future surveys may be compared. Univariate general modeling combined with ANOVA tests on the responses to the questions shows that education practices differ based on variables such as teaching style, communication with colleagues, years of teaching experience, faculty type, institution type, class size, and course type (introductory or major). These differences suggest opportunities for focused geoscience faculty development around education practices that support the success of a diverse population of undergraduate students and the enhancement of inclusive learning environments in the geosciences

    Method of Heating a Foam-Based Catalyst Bed

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    A method of heating a foam-based catalyst bed has been developed using silicon carbide as the catalyst support due to its readily accessible, high surface area that is oxidation-resistant and is electrically conductive. The foam support may be resistively heated by passing an electric current through it. This allows the catalyst bed to be heated directly, requiring less power to reach the desired temperature more quickly. Designed for heterogeneous catalysis, the method can be used by the petrochemical, chemical processing, and power-generating industries, as well as automotive catalytic converters. Catalyst beds must be heated to a light-off temperature before they catalyze the desired reactions. This typically is done by heating the assembly that contains the catalyst bed, which results in much of the power being wasted and/or lost to the surrounding environment. The catalyst bed is heated indirectly, thus requiring excessive power. With the electrically heated catalyst bed, virtually all of the power is used to heat the support, and only a small fraction is lost to the surroundings. Although the light-off temperature of most catalysts is only a few hundred degrees Celsius, the electrically heated foam is able to achieve temperatures of 1,200 C. Lower temperatures are achievable by supplying less electrical power to the foam. Furthermore, because of the foam s open-cell structure, the catalyst can be applied either directly to the foam ligaments or in the form of a catalyst- containing washcoat. This innovation would be very useful for heterogeneous catalysis where elevated temperatures are needed to drive the reaction

    Biochemical Characterization of a Filtered Synaptoneurosome Preparation from Guinea Pig Cerebral Cortex: Cyclic Adenosine 3’:5’-Monophosphate-generating Systems, Receptors, and Enzymes

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    A particulate preparation was obtained by low speed centrifugation of guinea pig cerebral cortical homogenates prepared with a Krebs-Henseleit buffer. Light microscopic examination, using a reflected light differential interference contrast system, reveals the presence of intact neurons, axonal fragments, glial cells, and erythrocytes along with an abundance of small spherical entities (diameter about 1.1 μm) and snowman-shaped entities (diameter of larger sphere about 1.1 μm, diameter of attached smaller sphere about 0.6 μm). Many unattached smaller spherical entities are also present (diameter about 0.6 μm). Pressure filtration through 5 or l0-μm Millipore filters, followed by low speed centrifugation and resuspension, removes most of the larger entities to afford a suspension composed mainly of the small spherical and snowman-shaped entities. Electron microscopic examination reveals the presence of many synaptosomes with attached resealed postsynaptic entities. It is proposed that these correspond to the snowman-shaped entities to be termed synaptoneurosomes. Accumulations of cyclic AMP elicited by 2-chloroadenosine and histamine, and by combinations of 2-chloroadenosine, histamine, norepinephrine, and forskolin, are lower in filtered than in unfiltered preparations, whereas accumulations elicited by forskolin are unchanged. Levels of adenylate cyclase are reduced by filtration, whereas levels of phosphodiesterase are unchanged. Filtration reduces levels of markers for whole cells and endothelial cells, whereas neuronal markers such as acetylcholinesterase activity and norepinephrine uptake are increased. Levels of S-100 protein, a marker for glial cells, are not significantly decreased. There is no apparent change in the density of many receptors or ion channels. Levels of A1-adenosine and H1-histamine receptors are increased, whereas levels of so-called peripheral benzodiazepine-binding sites are decreased

    Time Course of Dichoptic Masking in Normals and Suppression in Amblyopes

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    Purpose: To better understand the relationship between dichoptic masking in normal vision and suppression in amblyopia we address three questions: First, what is the time course of dichoptic masking in normals and amblyopes? Second, is interocular suppression low-pass or band-pass in its spatial dependence? And third, in the above two regards, is dichoptic masking in normals different from amblyopic suppression? Methods: We measured the dependence of dichoptic masking in normal controls and amblyopes on the temporal duration of presentation under three conditions; monocular (the nontested eye—i.e., dominant eye of normals or nonamblyopic eye of amblyopes, being patched), dichoptic-luminance (the nontested eye seeing a mean luminance—i.e., a DC component) and dichoptic-contrast (the nontested eye seeing high-contrast visual noise). The subject had to detect a letter in the other eye, the contrast of which was varied. Results: We found that threshold elevation relative to the patched condition occurred in both normals and amblyopes when the nontested eye saw either 1/f or band-pass filtered noise, but not just mean luminance (i.e., there was no masking from the DC component that corresponds to a channel responsive to a spatial frequency of 0 cyc/deg); longer presentation of the target (corresponding to lower temporal frequencies) produced greater threshold elevation. Conclusions: Dichoptic masking exhibits similar properties in both subject groups, being low-pass temporally and band-pass spatially, so that masking was greatest at the longest presentation durations and was not greatly affected by mean luminance in the nontested eye

    Trends in Race/Ethnicity of Pediatric Residents and Fellows: 2007-2019

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    BACKGROUND AND OBJECTIVES: A diverse pediatric workforce reflecting the racial/ethnic representation of the US population is an important factor in eliminating health inequities. Studies reveal minimal improvements over time in the proportions of underrepresented in medicine (URiM) physicians; however, studies assessing trends in pediatric URiM trainee representation are limited. Our objective was to evaluate longitudinal trends in racial/ethnic representation among a cross-section of US pediatric trainees and to compare it to the US population. METHODS: Repeated cross-sectional study of graduate medical education census data on self-reported race/ethnicity of pediatric residents and subspecialty fellows from 2007 to 2019. To evaluate trends in URiM proportions over time, the Cochran-Armitage test was performed. Data on self-reported race/ethnicity of trainees were compared with the general population data over time by using US Census Bureau data. RESULTS: Trends in URiM proportions were unchanged in residents (16% in 2007 to 16.5% in 2019; CONCLUSIONS: The continued underrepresentation of URiM pediatric trainees may perpetuate persistent health inequities for minority pediatric populations. There is a critical need to recruit and retain pediatric URiM residents and subspecialty fellows

    Stability Analysis of a Model of Atherogenesis: An Energy Estimate Approach II

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    This paper considers modelling atherogenesis, the initiation of atherosclerosis, as an inflammatory instability. Motivated by the disease paradigm articulated by Russell Ross, atherogenesis is viewed as an inflammatory spiral with positive feedback loop involving key cellular and chemical species interacting and reacting within the intimal layer of muscular arteries. The inflammation is modelled through a system of non-linear reaction–diffusion–convection partial differential equations. The inflammatory spiral is initiated as an instability from a healthy state which is defined to be an equilibrium state devoid of certain key inflammatory markers. Disease initiation is studied through a linear, asymptotic stability analysis of a healthy equilibrium state. Various theorems are proved giving conditions on system parameters guaranteeing stability of the health state and conditions on system parameters leading to instability. Among the questions addressed in the analysis is the possible mitigating effect of anti-oxidants upon transition to the inflammatory spiral
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