Plasma Magnetohydrodynamics and Energy Conversion

Contains reports on four research projects.National Science Foundation (Grant G-24073)United States Air Force, Aeronautical Systems Division, Aeronautical Accessories Laboratory, Wright-Patterson Air Force Base (Contract AF33(616)-7624

Geographical trends in research: a preliminary analysis on authors' affiliations

In the last decade, research literature reached an enormous volume with an unprecedented current annual increase of 1.5 million new publications. As research gets ever more global and new countries and institutions, either from academia or corporate environment, start to contribute with their share, it is important to monitor this complex scenario and understand its dynamics. We present a study on a conference proceedings dataset extracted from Springer Nature Scigraph that illustrates insightful geographical trends and highlights the unbalanced growth of competitive research institutions worldwide. Results emerged from our micro and macro analysis show that the distributions among countries of institutions and papers follow a power law, and thus very few countries keep producing most of the papers accepted by high-tier conferences. In addition, we found that the annual and overall turnover rate of the top 5, 10 and 25 countries is extremely low, suggesting a very static landscape in which new entries struggle to emerge. Finally, we highlight the presence of an increasing gap between the number of institutions initiating and overseeing research endeavours (i.e. first and last authors' affiliations) and the total number of institutions participating in research. As a consequence of our analysis, the paper also discusses our experience in working with affiliations: an utterly simple matter at first glance, that is instead revealed to be a complex research and technical challenge yet far from being solved

Effect of progressive mandibular advancement on pharyngeal airway size in anesthetized adults.

BACKGROUND: General anesthesia in adult humans is associated with narrowing or complete closure of the pharyngeal airway. The purpose of this study was to determine the effect of progressive mandibular advancement on pharyngeal airway size in normal adults during intravenous infusion of propofol for anesthesia. METHODS: Magnetic resonance imaging was performed in nine normal adults during wakefulness and during propofol anesthesia. A commercially available intraoral appliance was used to manually advance the mandible. Images were obtained during wakefulness without the appliance and during anesthesia with the participants wearing the appliance under three conditions: without mandibular advancement, advancement to 50% maximum voluntary advancement, and maximum advancement. Using computer software, airway area and maximum anteroposterior and lateral airway diameters were measured on the axial images at the level of the soft palate, uvula, tip of the epiglottis, and base of the epiglottis. RESULTS: Airway area across all four airway levels decreased during anesthesia without mandibular advancement compared with airway area during wakefulness (P \u3c 0.007). Across all levels, airway area at 50% advancement during anesthesia was less than that at centric occlusion during wakefulness (P = 0.06), but airway area with maximum advancement during anesthesia was similar to that during wakefulness (P = 0.64). In general, anteroposterior and lateral airway diameters during anesthesia without mandibular advancement were decreased compared with wakefulness and were restored to their wakefulness values with 50% and/or maximal advancement. CONCLUSIONS: Maximum mandibular advancement during propofol anesthesia is required to restore the pharyngeal airway to its size during wakefulness in normal adults

Multidisciplinary Applications of Detached-Eddy Simulation to Separated Flows at High Reynolds Numbers

We focus on multidisciplinary applications of detached-eddy simulation (DES), principally flight mechanics and aeroelasticity. Specifically, the lateral instability (known as abrupt wing stall) of the preproduction F/A-18E is reproduced using DES, including the unsteady shock motion. The presence of low frequency pressure oscillations due to shock motion in the current simulations and the experiments motivated a full aircraft calculation, which showed low frequency high-magnitude rolling moments that could be a significant contributor to the abrupt wing stall phenomenon. DES is also applied to the F-18 high angle of attack research vehicle (HARV) at a moderate angle of attack to reproduce the vortex breakdown leading to vertical stabilizer buffet. Unsteady tail loads are compared to flight test data. This work lays the foundation for future deforming grid calculations to reproduce the aero-elastic tail buffet seen in flight test. Solution based grid adaption is used on unstructured grids in both cases to improve the resolution in the separated region. Previous DoD Challenge work has demonstrated the unique ability of the DES turbulence treatment to accurately and efficiently predict flows with massive separation at flight Reynolds numbers. DES calculations have been performed using the Cobalt code and on unstructured grids, an approach that can deal with complete configurations with very few compromises. A broad range of flows has been examined in previous Challenge work, including aircraft forebodies, airfoil sections, a missile afterbody, vortex breakdown on a delta wing, and the F-16 and F-15E at high angles-of-attack. All DES predictions exhibited a moderate to significant improvement over results obtained using traditional Reynolds-averaged models and often excellent agreement with experimental/flight-test data. DES combines the efficiency of a Reynolds-averaged turbulence model near the wall with the fidelity of Large-Eddy Simulation (LES) in separated regions. Since it uses Large-Eddy Simulation in the separated regions, it is capable of predicting the unsteady motions associated with separated flows. The development and demonstration of improved methods for the prediction of flight mechanics and aeroelasticity in this Challenge is expected to reduce the acquisition cost of future military aircraft

Plasma Magnetohydrodynamics and Energy Conversion

Contains research objectives and reports on x research projects.National Science Foundation under Grant G-9330U.S. Air Force (Aeronautical Systems Division) under Contract AF33(616)-7624 with the Flight Accessories Laboratory, Wright-Patterson Air Force Base, Ohi

Plasmas and Controlled Nuclear Fusion

Contains research objectives and reports on four research projects.National Science Foundation (Grant GK-614)National Science Foundation (Grant GK-57

Can a concern for status reconcile diverse social welfare programs?

Let there be two individuals: “rich,” and “poor.” Due to inefficiency of the income redistribution policy, if a social planner were to tax the rich in order to transfer to the poor, only a fraction of the taxed income would be given to the poor. Under such inefficiency and a standard utility specification, a Rawlsian social planner who seeks to maximize the utility of the worst-off individual will select a different allocation of incomes than a utilitarian social planner who seeks to maximize the sum of the individuals’ utilities. However, when individuals prefer not only to have more income but also not to have low status conceptualized as low relative income, and when this distaste is incorporated in the individuals’ utility functions with a weight that is greater than a specified critical level, then a utilitarian social planner will select the very same income distribution as a Rawlsian social planner

Additional roles of a peripheral loop–loop interaction in the Neurospora VS ribozyme

Many RNAs contain tertiary interactions that contribute to folding the RNA into its functional 3D structure. In the VS ribozyme, a tertiary loop–loop kissing interaction involving stem–loops I and V is also required to rearrange the secondary structure of stem–loop I such that nucleotides at the base of stem I, which contains the cleavage–ligation site, can adopt the conformation required for activity. In the current work, we have used mutants that constitutively adopt the catalytically permissive conformation to search for additional roles of the kissing interaction in vitro. Using mutations that disrupt or restore the kissing interaction, we find that the kissing interaction contributes ∼1000-fold enhancement to the rates of cleavage and ligation. Large Mg2+-dependent effects on equilibrium were also observed: in the presence of the kissing interaction cleavage is favored >10-fold at micromolar concentrations of Mg2+; whereas ligation is favored >10-fold at millimolar concentrations of Mg2+. In the absence of the kissing interaction cleavage exceeds ligation at all concentrations of Mg2+. These data provide evidence that the kissing interaction strongly affects the observed cleavage and ligation rate constants and the cleavage–ligation equilibrium of the ribozyme

Plasma Magnetohydrodynamics and Energy Conversion

Contains reports on eight research projects.National Science Foundation (Grant G-24073)United States Air Force, Aeronautical Systems Division, Aeronautical Accessories Laboratory, Wright-Patterson Air Force Base (Contract AF33(616)-7624)United States Air Force, Office of Scientific Research of the Office of Aerospace Research (Research Grant No. 62-308