1,004 research outputs found

    Numerical simulation of flows in curved diffusers with cross-sectional transitioning using a three-dimensional viscous analysis

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    A three dimensional analysis for fully viscous, subsonic, compressible flow is evaluated. An approximate form of the Navier Stokes equations is solved by an implicit spatial marching technique. Calculations were made for flow in a circular S duct and in the F 16 inlet duct. The computed total pressure contours and secondary flow velocity vectors are presented. Qualitative comparisons with experiment are shown for both ducts. The analysis is used to show how the cross section transitioning in the F 16 inlet suppresses the development of a secondary flow vortex

    The Proteus Navier-Stokes code

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    An effort is currently underway at NASA Lewis to develop two- and three-dimensional Navier-Stokes codes, called Proteus, for aerospace propulsion applications. The emphasis in the development of Proteus is not algorithm development or research on numerical methods, but rather the development of the code itself. The objective is to develop codes that are user-oriented, easily-modified, and well-documented. Well-proven, state-of-the-art solution algorithms are being used. Code readability, documentation (both internal and external), and validation are being emphasized. This paper is a status report on the Proteus development effort. The analysis and solution procedure are described briefly, and the various features in the code are summarized. The results from some of the validation cases that have been run are presented for both the two- and three-dimensional codes

    Temporal variability in large grazer space use in an experimental landscape

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    Citation: Raynor, E. J., Joern, A., Skibbe, A., Sowers, M., Briggs, J. M., Laws, A. N., & Goodin, D. (2017). Temporal variability in large grazer space use in an experimental landscape. Ecosphere, 8(1), 18. doi:10.1002/ecs2.1674Land use, climate change, and their interaction each have great potential to affect grazing systems. With anticipated more frequent and extensive future drought, a more complete understanding of the mechanisms that determine large grazer landscape-level distribution under varying climatic conditions is integral to ecosystem management. Using an experimental setting with contrasting fire treatments, we describe the inter-annual variability of the effect of landscape topography and disturbance from prescribed spring fire on large grazer space use in years of variable resource availability. Using GPS telemetry, we investigated space use of plains bison (Bison bison bison) as they moved among watersheds managed with variable experimental burn treatments (1-, 2-, 4-, and 20-year burn intervals) during a seven-year period spanning years of average-to-above average forage production and severe drought. At the landscape scale, bison more strongly favored high-elevation and recently burned watersheds with watersheds burned for the first time in 2 or 4 yr consistently showing higher use relative to annually burned watersheds. In particular, watersheds burned for the first time in 4 yr were avoided to lesser extent than other more frequently burned watersheds during the dormant season. This management type also maintained coupling between bison space use and post-fire regrowth across post-drought growing season months, whereas watersheds with more frequent fire-return intervals attracted bison in only the first month post-fire. Hence, fire frequency played a role in maintaining the coupling of grazer and post-fire regrowth, the fire-grazer interaction, in response to drought-induced reduction in fuel loads. Moreover, bison avoided upland habitat in poor forage production years, when forage regrowth is less likely to occur in upland than in lowland habitats. Such quantified responses of bison to landscape features can aid future conservation management efforts and planning to sustain fire-grazer interactions and resulting spatial heterogeneity in grassland ecosystems

    Backpacks for Success: Interpersonal Reactions of Preservice Teachers in an Equity-Based Simulation

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    Empathy was identified as the initial variable of interest in the Backpacks for Success Simulation (BPSS). BPSS is a simulation exercise designed by Dr. Joel L. Billingsley in 2019. This simulation had its first debut at the 2019 Southeastern Regional Robert Noyce Conference. BPSS was used as an equity exercise to foster awareness for K-12 teachers and post-secondary educators. The purpose of this dissertation study was to build on the knowledge of BPSS intervention by conducting a mixed methods study that assessed participants empathic experiences in the BPSS. The Interpersonal Reactivity Index (IRI) survey was used before and after the simulation to quantitatively assess if there was a change in four dimensions (Empathic Concern, Perspective-taking, Fantasy, and Personal Distress) of empathy as a result of the BPSS. Open-ended survey questions were added to the end of the IRI survey. This data were used to learn more about the participant’s experience in BPSS. Throughout the simulation, participants wrote notes and placed them in each group’s Backpack. This data were collected throughout the simulation and were used to phenomenologically assess participants’ experience with BPSS. Participants were 32 pre-service teachers from a secondary teacher preparation program attending a southern university. Participant’s self-reported as studying social studies, english, science, and special education while pursuing bachelor’s and master’s degrees. The group consisted of males and females that identified as White, African American, and multiple races. The IRI quantitative data showed there was no significant difference in participants’ empathy before or after the simulation. Additionally, subscale measures revealed one significant difference on the Perspective-Taking (PT) subscale. This difference indicated participants’ saw a decline in their ability to take perspective from the beginning of the study. Although there was no significant difference in the Empathic Concern (EC) subscale, it is worth noting that the sample of participants were already high in EC entering the study. The qualitative data indicated participants\u27 had an array of experiences that fell within a continuum of resistance to the simulation to emerging toward empathy. This mixed research design led to a meta-inference that indicates participants can take on the perspective of others but decline in their ability to perspective take as the simulation progresses. Simultaneously there is a slow rise in the amount of empathic concern that the participants experience toward the end and completion of the BPSS. Findings from this study indicate a need to further explore empathy in the student teacher relationship and build upon Instructional Design implications to foster more xiii empathic atmospheres for learners of marginalized communities

    The Familial Clustering of Age at Menarche in Extended Twin Families

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    The timing of puberty is complex, possibly involving many genetic factors that may interact with environmental influences. Familial resemblance for age at menarche was studied in a sample of 4,995 female twins, 1,296 sisters, 2,946 mothers and 635 female spouses of male twins. They had indicated their age at menarche as part of a larger longitudinal survey. We assessed assortative mating for age at menarche, gene–environment interaction effects and estimated the heritability of individual differences in pubertal timing. There was significant evidence of gene–environment interaction, accounting for 1.5% of the variance. There was no indication of consistent mate assortment on age at menarche. Individual differences in age at menarche are highly heritable, with additive genetic factors explaining at least 70% of the true variation. An additional 1.5% of the variation can be explained by a genotype–environment interaction effect where environmental factors are more important in individuals genetically predisposed for late menarche

    Clinical heterogeneity associated with KCNA1 mutations include cataplexy and nonataxic presentations

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    Mutations in the KCNA1 gene are known to cause episodic ataxia/myokymia syndrome type 1 (EA1). Here, we describe two families with unique presentations who were enrolled in an IRB-approved study, extensively phenotyped, and whole exome sequencing (WES) performed. Family 1 had a diagnosis of isolated cataplexy triggered by sudden physical exertion in multiple affected individuals with heterogeneous neurological findings. All enrolled affected members carried a KCNA1 c.941T>C (p.I314T) mutation. Family 2 had an 8-year-old patient with muscle spasms with rigidity for whom WES revealed a previously reported heterozygous missense mutation in KCNA1 c.677C>G (p.T226R), confirming the diagnosis of EA1 without ataxia. WES identified variants in KCNA1 that explain both phenotypes expanding the phenotypic spectrum of diseases associated with mutations of this gene. KCNA1 mutations should be considered in patients of all ages with episodic neurological phenotypes, even when ataxia is not present. This is an example of the power of genomic approaches to identify pathogenic mutations in unsuspected genes responsible for heterogeneous diseases

    Using Extended Genealogy to Estimate Components of Heritability for 23 Quantitative and Dichotomous Traits

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    Important knowledge about the determinants of complex human phenotypes can be obtained from the estimation of heritability, the fraction of phenotypic variation in a population that is determined by genetic factors. Here, we make use of extensive phenotype data in Iceland, long-range phased genotypes, and a population-wide genealogical database to examine the heritability of 11 quantitative and 12 dichotomous phenotypes in a sample of 38,167 individuals. Most previous estimates of heritability are derived from family-based approaches such as twin studies, which may be biased upwards by epistatic interactions or shared environment. Our estimates of heritability, based on both closely and distantly related pairs of individuals, are significantly lower than those from previous studies. We examine phenotypic correlations across a range of relationships, from siblings to first cousins, and find that the excess phenotypic correlation in these related individuals is predominantly due to shared environment as opposed to dominance or epistasis. We also develop a new method to jointly estimate narrow-sense heritability and the heritability explained by genotyped SNPs. Unlike existing methods, this approach permits the use of information from both closely and distantly related pairs of individuals, thereby reducing the variance of estimates of heritability explained by genotyped SNPs while preventing upward bias. Our results show that common SNPs explain a larger proportion of the heritability than previously thought, with SNPs present on Illumina 300K genotyping arrays explaining more than half of the heritability for the 23 phenotypes examined in this study. Much of the remaining heritability is likely to be due to rare alleles that are not captured by standard genotyping arrays

    Gentle, Be Thy Footfall

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    80.7568.405 – “Gentle, Be Thy Footfall”: Composed by Towne, T. Martin: Carrol, Emily B.: S. Brainard & Co.: Cleveland: Minstrel, Ballad, Lost Love: 1860: Song and Chorus
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