Experimental Investigation And Analysis Of High-Enthalpy Nitrogen Flow Over Graphite

The high-enthalpy flow generated by hypersonic vehicles traveling within the Earth\u27s atmosphere inherently delivers an elevated heat flux to the vehicle surface. In addition to conductive heating, the liberated energy generated by various exothermic chemical reactions occurring at the vehicle surface further augment the total heat load. Quantifying the rates at which these reactions take place is imperative and remains a significant challenge as developers attempt to design the next generation of thermal protection systems. This study focused on nitrogen recombination and carbon nitridation, as these reactions are ubiquitous to the most aggressive atmospheric re-entry trajectories in which carbon-based ablative heat shields are conventionally employed. The 30-kW inductively coupled plasma torch located within the Plasma Diagnostics and Test Laboratory at the University of Vermont was used to produce high-enthalpy nitrogen plasma flow, which sufficiently simulated the various in-flight heat flux processes. A combination of optical-based techniques, including spontaneous emission spectroscopy and laser induced fluorescence were utilized to study the free jet and the interaction of the flow with samples constructed from POCO graphite. Emission measurements within the free stream indicated that the nitrogen flow was in non-equilibrium due to the inverse predissociation of ground state nitrogen atoms into the v = 13 vibrational level of the molecular nitrogen electronic B-state. The degree of non-equilibrium was quantified by determining the overpopulation of ground state nitrogen with respect to equilibrium and its effects were considered throughout the analysis. Results obtained through emission spectroscopy and laser induced fluorescence confirmed that the graphite material behaved as a catalytic surface that actively promoted nitrogen recombination. Additionally, the calculated carbon nitridation rate was several orders less efficient, although its effect on the sample surface erosion was evident in the sample mass loss measurements. Subsequently, an independent set of heat flux measurements performed over materials of varying catalycities further supported the data obtained with optical diagnostics. Furthermore, the heat flux results yielded the surface accommodation factor of graphite for the nitrogen recombination rate and indicated that the surface was slightly less than fully-accommodating

Virtual Team Coopetition: An Investigation of Coopetitive Proclivity in Virtual and Face-to-Face Female Dyads

The use of virtual teams (VTs) in the workplace has increased rapidly as companies seek to coordinate the collaboration of geographically dispersed employees effectively. This study involved an experimental comparison of VTs and face-to-face teams engaged in coopetition. Coopetition occurs when a relationship is characterized by simultaneous cooperation and competition. This study differed from previous research because many previous studies of team coopetition place their focus on traditional face-to-face teams and fail to touch upon the intricacies of VT coopetition. Because of this, investigating the intricacies of coopetition among VT members is an essential addition to the large body of research on face-to-face teams. This study examined team coopetition through separate measures of competitiveness and cooperativeness. The constructs competitiveness and cooperativeness were measured separately instead of together on a single continuum. This method determined team members’ coopetitive proclivities, the balance between one’s tendency to perform behaviors directed toward achieving a self-serving goal or goals and one’s tendency to perform behaviors directed toward achieving a group-serving goal or goals within the context of a coopetitive relationship. Team members’ coopetitive proclivities were examined through a combination of videogame play and electronic surveys. All participants in this experiment were female. No significant differences between the coopetitive proclivities of virtual and face-to-face teams were found. We found that the ratings of competence that participants received from their partners tended to be lower under the virtual condition. We found that extroverted team members were more likely to cooperate. We also found that the ratings of competitiveness that participants received from their partners were negatively correlated with the ratings of desirability for future collaboration (i.e., team viability) that participants received from their partners. Further, it was determined that the ratings of cooperativeness that participants received from their partners were positively correlated with the ratings of team viability that participants received from their partners. Additional results indicated a positive relationship between team members’ self-reported levels of agreeableness and the ratings of competence that participants received from their partners. Results also indicated a positive relationship between team members’ self-reported levels of openness and the ratings of competence that participants received from their partners. This paper discusses the implications of these results and possible directions for future study

Nonparent-Friendly Work Climate & Parental Role Value: An Updated Approach To Understanding Nonparent Work Experiences

First, the present study entails a theoretically guided examination of relationships between nonparent-friendly organizational climate (NPFC) and important outcomes among nonparent workers. Second, the present study explores the role of social-identity theory in understanding nonparent work experiences by examining and comparing the function (i.e., moderation effect sizes) of parental role values and parental expectations (i.e., childfree status) on relationships between NPFC and outcomes including affective commitment. Third, the present study compares the relevance of NPFC and singles-friendly culture in the prediction of outcomes among nonparent workers. Lastly, the present study examines the potential role of intersectionality of nonparental role and gender in anticipated relationships between NPFC and outcomes among nonparents. In the process, the present study replicates and expands on past research aimed at elucidating the nuances of what it means to be a nonparent at work. Results may inform how researchers and practitioners engage with and operationalize social identities in the workplace, whether social identities moderate (i.e., magnify) important outcomes for workers, and whether NPFC (compared to a measure of singles-friendly organizational culture) is a more appropriate measure of the friendliness of the workplace for nonparents

Recovery of Oregon Coast Coho Salmon (Onchorhynchus kitsutch) through Restoration of Freshwater Habitats

Pacific salmon populations are significantly lower than historic levels on the Western Coast of the United States. The Oregon Coast coho salmon Evolutionary Significant Unit (ESU) was listed as threatened under the Endangered Species Act in February 2008. The total number of adult coho salmon returning to Oregon Coast rivers today are between 5-20% of historic levels. Since the 1980s, restoration of freshwater habitat has become a common practice in the attempt to recover Pacific salmon populations. I used two databases, the Oregon Watershed Restoration Inventory, and the Salmon Recovery Tracker, to analyze habitat restoration and coho salmon population recovery on the Oregon Coast. A total of $145,620,716 was spent on 4,173 restoration projects on the Oregon Coast streams from 1997-2012. I hypothesized that the restoration actions had resulted in a significant increase in adult coho abundance on the Oregon Coast. My analysis showed that from 1994 to 2012 only 3 of the 21 independent populations from the ESU, the Alsea, Salmon, and Tillamook had statistically significant recovery. I ran a correlation between the rate of recovery and the amount spent on restoration for each ESU population. The rate of recovery increased as total dollars spent on restoration increased, but it was a very weak relationship. Additional monitoring and more advanced statistical analysis may provide a greater understanding of the relationship between coho salmon and their freshwater habitat

High resolution near-infrared imaging of submillimeter galaxies

We present F110W (~J) and F160W (~H) observations of ten submillimeter galaxies (SMGs) obtained with the Hubble Space Telescope's (HST's) NICMOS camera. Our targets have optical redshifts in the range 2.20<z<2.81 confirmed by millimeter CO or mid-IR spectroscopy, guaranteeing that the two bands sample the rest-frame optical with the Balmer break falling between them. Eight of ten are detected in both bands, while two are detected in F160W only. We study their F160W morphologies, applying a maximum-deblending detection algorithm to distinguish multiple- from single-component configurations, leading to reassessments for several objects. Based on our NICMOS imaging and/or previous dynamical evidence we identify five SMGs as multiple sources, which we interpret as merging systems. Additionally, we calculate morphological parameters asymmetry (A) and Gini coefficient (G); thanks to our sample's limited redshift range we recover the trend that multiple-component, merger-like morphologies are reflected in higher asymmetries. We analyze the stellar populations of nine objects with F110W/F160W photometry, using archival HST optical data when available. For multiple systems, we are able to model the individual components that build up an SMG. With the available data we cannot discriminate among star formation histories, but we constrain stellar masses and mass ratios for merger-like SMG systems, obtaining a mean log(M_*/M_sun)=10.9+/-0.2 for our full sample, with individual values log(M_*/M_sun)~9.6-11.8. The morphologies and mass ratios of the least and most massive systems match the predictions of the major-merger and cold accretion SMG formation scenarios, respectively, suggesting that both channels may have a role in the population's origin.Comment: 41 pages preprint, 3 figures, published in ApJ on 2013 May 1

Simultaneous multislice acquisition with multi-contrast segmented EPI for separation of signal contributions in dynamic contrast-enhanced imaging

We present a method to efficiently separate signal in magnetic resonance imaging (MRI) into a base signal S0, representing the mainly T1-weighted component without T2*-relaxation, and its T2*-weighted counterpart by the rapid acquisition of multiple contrasts for advanced pharmacokinetic modelling. This is achieved by incorporating simultaneous multislice (SMS) imaging into a multi-contrast, segmented echo planar imaging (EPI) sequence to allow extended spatial coverage, which covers larger body regions without time penalty. Simultaneous acquisition of four slices was combined with segmented EPI for fast imaging with three gradient echo times in a preclinical perfusion study. Six female domestic pigs, German-landrace or hybrid-form, were scanned for 11 minutes respectively during administration of gadolinium-based contrast agent. Influences of reconstruction methods and training data were investigated. The separation into T1- and T2*-dependent signal contributions was achieved by fitting a standard analytical model to the acquired multi-echo data. The application of SMS yielded sufficient temporal resolution for the detection of the arterial input function in major vessels, while anatomical coverage allowed perfusion analysis of muscle tissue. The separation of the MR signal into T1- and T2*-dependent components allowed the correction of susceptibility related changes. We demonstrate a novel sequence for dynamic contrast-enhanced MRI that meets the requirements of temporal resolution (Δt &lt; 1.5 s) and image quality. The incorporation of SMS into multi-contrast, segmented EPI can overcome existing limitations of dynamic contrast enhancement and dynamic susceptibility contrast methods, when applied separately. The new approach allows both techniques to be combined in a single acquisition with a large spatial coverage