4,923 research outputs found

    Dual-Pump CARS Measurements in the University of Virginia's Dual-Mode Scramjet: Configuration "A"

    Get PDF
    In this paper we describe efforts to obtain canonical data sets to assist computational modelers in their development of models for the prediction of mixing and combustion in scramjet combustors operating in the ramjet-scramjet transition regime. The CARS technique is employed to acquire temporally and spatially resolved measurements of temperature and species mole-fraction at four planes, one upstream of an H2 fuel injector and three downstream. The technique is described and results are presented for cases with and without chemical reaction. The vibrational energy mode in the heated airstream of the combustor was observed to be frozen at near facility heater conditions and significant nonuniformities in temperature were observed, attributed to nonuniformities of temperature exiting the heater. The measurements downstream of fuel injection show development of mixing and combustion, and are already proving useful to the modelers

    Molecular Analysis of Twist1 and FGF Receptors in a Rabbit Model of Craniosynostosis: Likely Exclusion as the Loci of Origin

    Get PDF
    Craniosynostosis is the premature fusion of the cranial vault sutures. We have previously described a colony of rabbits with a heritable pattern of nonsyndromic, coronal suture synostosis; however, the underlying genetic defect remains unknown. We now report a molecular analysis to determine if four genes implicated in human craniosynostosis, TWIST1 and fibroblast growth factor receptors 1–3 (FGFR1–3), could be the loci of the causative mutation in this unique rabbit model. Single nucleotide polymorphisms (SNPs) were identified within the Twist1, FGFR1, and FGFR2 genes, and the allelic patterns of these silent mutations were examined in 22 craniosynostotic rabbits. SNP analysis of the Twist1, FGFR1, and FGFR2 genes indicated that none were the locus of origin of the craniosynostotic phenotype. In addition, no structural mutations were identified by direct sequence analysis of Twist1 and FGFR3 cDNAs. These data indicate that the causative locus for heritable craniosynostosis in this rabbit model is not within the Twist1, FGFR1, and FGFR2 genes. Although a locus in intronic or flanking sequences of FGFR3 remains possible, no direct structural mutation was identified for FGFR3

    Dual-Pump CARS Measurements in the University of Virginia's Dual-Mode Scramjet: Configuration "C"

    Get PDF
    Measurements have been conducted at the University of Virginia Supersonic Combustion Facility in configuration C of the dual-mode scramjet. This is a continuation of previously published works on configuration A. The scramjet is hydrogen fueled and operated at two equivalence ratios, one representative of the scram mode and the other of the ram mode. Dual-pump CARS was used to acquire the mole fractions of the major species as well as the rotational and vibrational temperatures of N2. Developments in methods and uncertainties in fitting CARS spectra for vibrational temperature are discussed. Mean quantities and the standard deviation of the turbulent fluctuations at multiple planes in the flow path are presented. In the scram case the combustion of fuel is completed before the end of the measurement domain, while for the ram case the measurement domain extends into the region where the flow is accelerating and combustion is almost completed. Higher vibrational than rotational temperature is observed in those parts of the hot combustion plume where there is substantial H2 (and hence chemical reaction) present

    Chapter 2: Navigating the mentoring process in a research-based teacher development project: A situated learning perspective

    Get PDF
    In this article, the authors investigate key aspects of a 2-year study of mentoring within a reform-based teacher development project, explore the various mentor relationships, and theorize about key events, tensions, and dynamics that resulted in an unexpected sense of community among project stakeholders as a direct result of mentoring. Data for this article describe the impact of teacher mentoring within the Assessment Initiative for Middle School Physical Education (AIMS-PE) project. AIMS-PE was a multi-year Center for Disease Control grant funded project with goals including assisting in-service teachers to examine and reframe their assessment practices and to increase their students. knowledge and behaviors of physical activity. Initiation and development of positive mentoring relationships among participating teachers and their mentors was a major component of this effort, providing necessary support and encouragement to meet project objectives. Also, the authors explore participants\u27 experiences in the project to better understand the influences of teacher mentoring that contributed to the development of a sense of community

    Measurement of Vibrational Non-Equilibrium in a Supersonic Freestream Using Dual-Pump CARS

    Get PDF
    Measurements have been conducted at the University of Virginia Supersonic Combustion Facility of the flow in a constant area duct downstream of a Mach 2 nozzle, where the airflow has first been heated to approximately 1200 K. Dual-pump CARS was used to acquire rotational and vibrational temperatures of N2 and O2 at two planes in the duct at different downstream distances from the nozzle exit. Wall static pressures in the nozzle are also reported. With a flow of clean air, the vibrational temperature of N2 freezes at close to the heater stagnation temperature, while the O2 vibrational temperature is about 1000 K. The results are well predicted by computational fluid mechanics models employing separate "lumped" vibrational and translational/rotational temperatures. Experimental results are also reported for a few percent steam addition to the air and the effect of the steam is to bring the flow to thermal equilibrium

    The BRAIN-Q, a tool for assessing self-reported sport-related concussions for epidemiological studies

    Get PDF
    Objectives: The BRAIN-Q is a tool aimed at maximising the accuracy, and minimising measurement error, for retrospectively assessing concussions. This paper reports agreement of the BRAIN-Q tool when compared to extant questionnaire questions, and reproducibility when compared with its telephonic version (tBRAIN-Q). Method: The BRAIN-Q entails a 3-stage process: defining concussion, creating a visual timeline with life events, and establishing detailed characteristics for each reported concussion. It was designed to be administered in-person by trained personnel, and was used in the BRAIN Study. Its performance was compared with the MSK Study which previously collected a few questions in a broader self-administered questionnaire; and with the tBRAIN-Q Recall, its telephonic version. Results: 101 participants were included; of these, nine were re-assessed with the tBRAIN-Q. Compared to the BRAIN-Q, the agreement with the MSK-Q for rugby-related concussion was 86.7% (kappa 0.6). Rugby-related concussion with loss of consciousness showed lower agreement (82.0% (kappa 0.6)). The comparison between the BRAIN-Q and the tBRAIN-Q showed a good reproducibility. Conclusions: The BRAIN-Q is a relatively easy tool to administer in face-to-face assessments, it showed an optimal reproducibility, it includes a well-established definition of concussion, and is used to collect detailed information on each concussion allowing for a number of subgroup analyses (e.g. by severity, by age, by context). The BRAIN-Q is easily adaptable to other sporting setting
    corecore