Introduction of laser initiation for the 48-inch Advanced Solid Rocket Motor (ASRM) test motors at Marshall Space Flight Center (MSFC)

The Advanced Solid Rocket Motor is a new design for the Space Shuttle Solid Rocket Booster. The new design will provide more thrust and more payload capability, as well as incorporating many design improvements in all facets of the design and manufacturing process. A 48-inch (diameter) test motor program is part of the ASRM development program. This program has multiple purposes for testing of propellent, insulation, nozzle characteristics, etc. An overview of the evolution of the 48-inch ASRM test motor ignition system which culminated with the implementation of a laser ignition system is presented. The laser system requirements, development, and operation configuration are reviewed in detail

The Megamaser Cosmology Project. VII. Investigating disk physics using spectral monitoring observations

We use single-dish radio spectra of known 22 GHz H$_2$O megamasers, primarily gathered from the large dataset observed by the Megamaser Cosmology Project, to identify Keplerian accretion disks and to investigate several aspects of the disk physics. We test a mechanism for maser excitation proposed by Maoz & McKee (1998), whereby population inversion arises in gas behind spiral shocks traveling through the disk. Though the flux of redshifted features is larger on average than that of blueshifted features, in support of the model, the high-velocity features show none of the predicted systematic velocity drifts. We find rapid intra-day variability in the maser spectrum of ESO 558-G009 that is likely the result of interstellar scintillation, for which we favor a nearby ($D \approx 70$ pc) scattering screen. In a search for reverberation in six well-sampled sources, we find that any radially-propagating signal must be contributing $\lesssim$10% of the total variability. We also set limits on the magnetic field strengths in seven sources, using strong flaring events to check for the presence of Zeeman splitting. These limits are typically 200--300 mG ($1\sigma$), but our most stringent limits reach down to 73 mG for the galaxy NGC 1194.Comment: Accepted for publication in Ap

Radio continuum of galaxies with H2_{2}O megamaser disks: 33 GHz VLA data

We investigate the nuclear environment of galaxies with observed 22 GHz water megamaser in their subparsec edge-on accretion disks, using 33 GHz (9mm) radio continuum data from VLA, with a resolution of ~ 0.2-0.5 arcsecs, and relate the maser and host galaxy properties to those of its radio continuum emission. Eighty-seven percent (21 out of 24) galaxies in our sample show 33 GHz radio continuum emission at levels of 4.5-240 $\sigma$. Five sources show extended emission, including one source with two main components and one with three main components. The remaining detected 16 sources exhibit compact cores within the sensitivity limits. Little evidence is found for extended jets (>300 pc) in most sources. Either they do not exist, or our chosen frequency of 33 GHz is too high for a detection of these supposedly steep spectrum features. In only one source among those with known maser disk orientation, NGC4388, we found an extended jet-like feature that appears to be oriented perpendicular to the water megamaser disk. Smaller 100-300 pc sized jets might also be present, as is suggested by the beam-deconvolved morphology of our sources. Whenever possible, central positions with accuracies of 20-280 mas are provided. A correlation analysis shows that the 33 GHz luminosity weakly correlates with the infrared luminosity. The 33 GHz luminosity is anticorrelated with the circular velocity of the galaxy. The black hole masses show stronger correlations with water maser luminosity than with 1.4 GHz, 33 GHz, or hard X-ray luminosities. Furthermore, the inner radii of the disks show stronger correlations with 1.4 GHz, 33 GHz, and hard X-ray luminosities than their outer radii, suggesting that the outer radii may be affected by disk warping, star formation, or peculiar density distributions.Comment: 18 pages, 10 figures, Accepted for publication in A&

Singularities of low entropy high codimension curve shortening flow

We consider curve shortening flow of arbitrary codimension in an Euclidean background. We show that, close to a singularity, the flow is asymptotically planar, paralleling Altschuler's work in the case of space curves, and analyse the blow-up limits of the flow. Using these results, we then prove that the curve shortening flow of initial curves with an entropy bound converges to a round point in finite time.Comment: 20 page

Factors Affecting Graduation with Honors: A Case Study in Business

Many first-year college students elect to enroll in their university’s honors program. These programs offer students many educational benefits not provided to non-honors students, such as smaller class sizes, priority registration, and added faculty interaction. However, of the students that enter the university as an honors student, many fail to complete their honors program. Researchers have documented completion rates as low as 18.45% (Campbell and Fuqua, 2008). So why are honors graduation rates so low? In this study, variables were examined that the literature suggests affects honors graduation rates (High School GPA, ACT/SAT scores, AP credits, GPA 1st term and GPA 2nd term, Ethnicity, Gender, first-generation and financial need status, as well as home state/country) to determine which of those may help explain completion of an honors program. The data for this study were incoming freshman honors students in the Walton College of Business (WCOB) at the University of Arkansas­–Fayetteville from 2004-2014. T-tests and chi square tests were used to determine if significant differences occurred within the observations of these factors in terms of graduating with honors and then used significant variables as the basis for a logit regression model where graduating with honors was the dependent variable. Based on the results of the chi square and t tests, we hypothesized eleven variables would explain whether or not a student graduated with honors. However, the final results suggest that only four factors had significant impacts on graduation with honors: GPA 1st term, high school GPA, number of AP credit hours brought into college and staying in WCOB all four years. There were limitations to the study. There are other variables, such as finding a good mentor, studying abroad, having to work, and having a poor work ethic that may have influence but were not included in this study. Future studies may want to look toward the relationship between honors graduation and the factors that were not covered in this study

Assessing Reliability of Expert Ratings Among Judges Responding to a Survey Instrument Developed to Study the Long Term Efficacy of the ABET Engineering Criteria, EC2000

In today’s assessment processes, especially those evaluations that rely on humans to make subjective judgements, it is necessary to analyze the quality of their ratings. The psychometric issues associated with assessment provide the lens through which researchers interpret results and important decisions are made. Therefore, inter-rater agreement (IRA) and inter-rater reliability (IRR) are pre-requisites for rater-dependent data analysis. A survey instrument cannot provide “good” information if it is not reliable; in other words, reliability is central to the validation of an instrument. When judges cannot be shown to reliably rate a performance, item, or target, the question becomes why the judges’ responses are different from one another. If the judges’ ratings covary unreliably because the construct is poorly defined or the rating framework is defective, then the resultant scores will have questionable meaning. On the other hand, if the judges’ ratings differ because they have a true difference in opinion, this is of importance to the researcher and may not necessarily diminish the validity of the scores. The intraclass correlation coefficient (ICC) is the most efficient method to assess these rater differences and identify the specific sources of inconsistency in measurement. This study examined how ICCs can be used to inform researchers of the extent in which legitimate differences of opinion may appear as a lack of reliability and/or agreement, demonstrating the need for analyzing survey data beyond standard descriptive statistics. Overall, both the IRA and IRR correlations, as calculated by ICC, ranged from .79 to .91 indicating high levels of agreement and consistency in the scoring among the judges\u27 ratings. When group membership was accounted for the IRA values increased suggesting the common judges agreed more than those judges who varied in their perspectives

Exploring relationships among communication, sexual satisfaction, and marital satisfaction

This study examined relationships among couple communication and sexual satisfaction in predicting marital satisfaction. The sample consisted of 387 married couples living in Chapel Hill, North Carolina. Regression analyses demonstrated that communication and sexual satisfaction independently predict marital satisfaction and that there is a significant interaction among communication and sexual satisfaction in predicting marital satisfaction. Exploration of this interaction revealed that if couples are successful at communicating constructively, sexual satisfaction fails to contribute to marital satisfaction. However, if couples have difficulty communicating, if they are also satisfied in their sexual relationship, they will evidence greater marital satisfaction. Thus, sexual satisfaction may act as a buffer for poor communication in impacting marital satisfaction. Clinical implications and future directions for research are outlined

Best Practices in ACPE Supervisory Education: Reflections of a Practitioner

Three questions shape the reflections in this article. 1) What is best practice in ACPE supervisory education? 2) What are examples of best practice in ACPE supervisory education? 3) Is there one set of best practices that will serve all ACPE supervisory education centers? Finally, conclusions about future challenges that face ACPE in providing supervisory education