319 research outputs found

    Physical lumping methods for developing linear reduced models for high speed propulsion systems

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    In gasdynamic systems, information travels in one direction for supersonic flow and in both directions for subsonic flow. A shock occurs at the transition from supersonic to subsonic flow. Thus, to simulate these systems, any simulation method implemented for the quasi-one-dimensional Euler equations must have the ability to capture the shock. In this paper, a technique combining both backward and central differencing is presented. The equations are subsequently linearized about an operating point and formulated into a linear state space model. After proper implementation of the boundary conditions, the model order is reduced from 123 to less than 10 using the Schur method of balancing. Simulations comparing frequency and step response of the reduced order model and the original system models are presented

    Comparative Study of the Extra-Curricular Activity Programs in Selected Middle and Junior High Schools in Pierce County Washington

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    The purpose of this project was to compare the differences in extra-curricular activity programs of middle and junior high schools in Pierce County (WA). To accomplish this purpose a review of current literature and research regarding extracurricular activity programs was conducted. Thirty-nine selected middle and junior high schools were surveyed to determine which extra-curricular activities were offered at their schools

    Phylogenetic Systematics of the Primate Genus Aotus Based on Hyoid Morphology

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    Dissection of a specimen of the South American primate genus Aotus was performed, focusing on the morphology of the hyoid apparatus and surrounding musculature within the hyoid region (the ventral side of the throat). Data collected from this dissection, along with data from published descriptions of primate genera from both primate suborders Haplorhini and Strepsirhini, were analyzed using the computer software program PAUP (Phylogenetic Analysis Using Parsimony). This analysis generated four equally probable phylogenetic trees (cladograms) depicting possible phylogenetic relationships of Aotus to other primates. While the cladograms differ in minor detail, they all show that Aotus appears to be more closely related to the more apomorphic suborder Haplorhini than to the Strepsirhini, and that it is a relatively plesiomorphous member of the haplorhine group. This suggests that the ancestor of the New World monkeys arrived in South America at about the time when haplorhine primates were beginning to diverge in the rest of the world, about 28 million years ago

    What’s in a surname? Physique, aptitude, and sports type comparisons between Tailors and Smiths

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    Combined heredity of surnames and physique, coupled with past marriage patterns and trade-specific physical aptitude and selection factors, may have led to differential assortment of bodily characteristics among present-day men with specific trade-reflecting surnames (Tailor vs. Smith). Two studies reported here were partially consistent with this genetic-social hypothesis, first proposed by Bäumler (1980). Study 1 (N = 224) indicated significantly higher self-rated physical aptitude for prototypically strength-related activities (professions, sports, hobbies) in a random sample of Smiths. The counterpart effect (higher aptitude for dexterity-related activities among Tailors) was directionally correct, but not significant, and Tailor-Smith differences in basic physique variables were not significant. Study 2 examined two large datasets (Austria/Germany combined, and UK: N = 7001 and 20532) of men’s national high-score lists for track-and-field events requiring different physiques. In both datasets, proportions of Smiths significantly increased from light-stature over medium-stature to heavy-stature sports categories. The predicted counterpart effect (decreasing prevalences of Tailors along these categories) was not supported. Related prior findings, implicit egotism as an alternative interpretation of the evidence, and directions for further inquiry are discussed in conclusion

    Mitochondrial genomes of giant deers suggest their late survival in Central Europe

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    The giant deer Megaloceros giganteus is among the most fascinating Late Pleistocene Eurasian megafauna that became extinct at the end of the last ice age. Important questions persist regarding its phylogenetic relationship to contemporary taxa and the reasons for its extinction. We analyzed two large ancient cervid bone fragments recovered from cave sites in the Swabian Jura (Baden-Württemberg, Germany) dated to 12,000 years ago. Using hybridization capture in combination with next generation sequencing, we were able to reconstruct nearly complete mitochondrial genomes from both specimens. Both mtDNAs cluster phylogenetically with fallow deer and show high similarity to previously studied partial Megaloceros giganteus DNA from Kamyshlov in western Siberia and Killavullen in Ireland. The unexpected presence of Megaloceros giganteus in Southern Germany after the Ice Age suggests a later survival in Central Europe than previously proposed. The complete mtDNAs provide strong phylogenetic support for a Dama-Megaloceros clade. Furthermore, isotope analyses support an increasing competition between giant deer, red deer, and reindeer after the Last Glacial Maximum, which might have contributed to the extinction of Megaloceros in Central Europe

    Self-projection in early childhood: no evidence for a common underpinning of episodic memory, episodic future thinking, theory of mind, and spatial navigation

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    Buckner and Carroll [Trends in Cognitive Sciences (2007), Vol. 11, pp. 49–57] argued that episodic memory (EM), episodic future think- ing (EFT), theory of mind (ToM), and spatial navigation all build on the same mental mechanism—self-projection, that is, the ability to disengage from the immediate present and shift perspective to alternative temporal, mental, or spatial situations. Developmental studies indeed show that all four abilities undergo profound developmental changes around 4 years of age, and there are first indications of developmental interrelations between some of the abilities. However, strong evidence for the self-projection account, namely that all four abilities are interrelated in their emergence during early childhood, is still lacking. To thoroughly investigate the self-projection hypothesis, we tested 151 4-year-old children on 12 different tasks assessing their EM, EFT, ToM, and spatial navigation skills (3 tasks per ability). Structural equation modeling under maximum likelihood estimation was conducted on a final sample of 144 children to evaluate a model with the 12 tasks as indicators and self-projection as the latent factor. The model showed a very good fit to the data. However, the factor loadings, indicating the strength of association between the latent factor and the indicators, were very low—which speaks against the validity of the measurement model. In summary, the results do not support the assumption of a common latent factor underlying the various abilities EM, EFT, ToM, and spatial navigation. Implications of our results for the self-projection account and possible related theoretical and methodological challenges are discussed.Education and Child Studie

    Solid-phase XRN1 reactions for RNA cleavage: application in single-molecule sequencing

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    Modifications in RNA are numerous (∼170) and in higher numbers compared to DNA (∼5) making the ability to sequence an RNA molecule to identify these modifications highly tenuous using next generation sequencing (NGS). The ability to immobilize an exoribonuclease enzyme, such as XRN1, to a solid support while maintaining its activity and capability to cleave both the canonical and modified ribonucleotides from an intact RNA molecule can be a viable approach for single-molecule RNA sequencing. In this study, we report an enzymatic reactor consisting of covalently attached XRN1 to a solid support as the groundwork for a novel RNA exosequencing technique. The covalent attachment of XRN1 to a plastic solid support was achieved using EDC/NHS coupling chemistry. Studies showed that the solid-phase digestion efficiency of model RNAs was 87.6 ± 2.8%, while the XRN1 solution-phase digestion for the same model was 78.3 ± 4.4%. The ability of immobilized XRN1 to digest methylated RNA containing m6A and m5C ribonucleotides was also demonstrated. The processivity and clipping rate of immobilized XRN1 secured using single-molecule fluorescence measurements of a single RNA transcript demonstrated a clipping rate of 26 ± 5 nt s−1 and a processivity of >10.5 kb at 25°C
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