6,193 research outputs found

    Effects of the Shuttle Orbiter fuselage and elevon on the molecular distribution of water vapor from the flash evaporator system

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    A concern has arisen regarding the emissive distribution of water molecules from the shuttle orbiter flash evaporator system (FES). The role of the orbiter fuselage and elevon in affecting molecular scattering distributions was nuclear. The effect of these components were evaluated. Molecular distributions of the water vapor effluents from the FE were measured. These data were compared with analytically predicted values and the resulting implications were calculated

    Catalytic Oxidation of Styrene in the Presence of Square Planar Cobalt(iii) Complexes of Polyanionic Chelating Ligands

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    Styrene has been catalytically oxidised in the presence of iodosoarenes and square planar cobalt(iii) complexes of polyanionic chelating (PAC) ligands; possible intermediates in these oxygen atom transfer reactions include cobalt(v)-oxo complexes

    Towards a Continuous Record of the Sky

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    It is currently feasible to start a continuous digital record of the entire sky sensitive to any visual magnitude brighter than 15 each night. Such a record could be created with a modest array of small telescopes, which collectively generate no more than a few Gigabytes of data daily. Alternatively, a few small telescopes could continually re-point to scan and reco rd the entire sky down to any visual magnitude brighter than 15 with a recurrence epoch of at most a few weeks, again always generating less than one Gigabyte of data each night. These estimates derive from CCD ability and budgets typical of university research projects. As a prototype, we have developed and are utilizing an inexpensive single-telescope system that obtains optical data from about 1500 square degrees. We discuss the general case of creating and storing data from a both an epochal survey, where a small number of telescopes continually scan the sky, and a continuous survey, composed of a constellation of telescopes dedicated each continually inspect a designated section of the sky. We compute specific limitations of canonical surveys in visible light, and estimate that all-sky continuous visual light surveys could be sensitive to magnitude 20 in a single night by about 2010. Possible scientific returns of continuous and epochal sky surveys include continued monitoring of most known variable stars, establishing case histories for variables of future interest, uncovering new forms of stellar variability, discovering the brightest cases of microlensing, discovering new novae and supernovae, discovering new counterparts to gamma-ray bursts, monitoring known Solar System objects, discovering new Solar System objects, and discovering objects that might strike the Earth.Comment: 38 pages, 9 postscript figures, 2 gif images. Revised and new section added. Accepted to PASP. Source code submitted to ASCL.ne

    The Interactive Question Protocol: Examining the Relationship Between Feedback, Cognitive Development and Student Achievement

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    Feedback is an essential component of effective learning. The advent of the internet as a delivery mode for distance education has expanded the access many people have to higher learning. Despite many advantages that online courses provide for distance learning students, they often lack real time feedback. A software intervention called the Interactive Question Protocol was designed for this study to provide automated, real time feedback. That treatment was then contrasted against changes in student achievement, satisfaction and participation. Learners can be categorized by Perry\u27s scheme of mental maturity according to how they understand and interpret the knowledge they acquire. Learners with low cognitive complexity levels are likely to appreciate basic automated feedback, while those with greater mental maturities are likely to be frustrated by a lack of true interaction. Therefore, Perry grouping was contrasted against changes in student achievement, satisfaction and participation for each subject. This study sought to discover if automated real time feedback had an effect on student achievement, participation and satisfaction. Similarly, it sought to discover if the same three variables were affected by cognitive complexity. Interactive effects between cognitive complexity and feedback treatment were also examined. No significant effects were found. The feedback treatment did not highlight group differences in achievement, satisfaction or participation. Group comparisons between the lower end of the cognitive complexity index scale also confirmed the null hypothesis. Sample sizes proved insufficient to compare subjects in Perry\u27s higher end groups 4 and 5. No interactive effects were found between independent variables. These findings do not refute the obvious value of feedback. Further studies may use a larger sample size to better compare Perry\u27s groups. More feedback complexity, along with the complexity of learning tasks may also be varied to investigate the impact of feedback on achievement, satisfaction and participation

    Geologic evaluation of anomalies between like-polarized and cross-polarized K-band side-looking radar imagery of Yellowstone National Park, 1965

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    Geologic evaluation of anomalies between like-polarized and cross-polarized K-band side-looking radar imagery of Yellowstone National Par

    Most of the genetic covariation between major depressive and alcohol use disorders is explained by trait measures of negative emotionality and behavioral control

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    Background Mental health disorders commonly co-occur, even between conceptually distinct syndromes, such as internalizing and externalizing disorders. The current study investigated whether phenotypic, genetic, and environmental variance in negative emotionality and behavioral control account for the covariation between major depressive disorder (MDD) and alcohol use disorder (AUD). Method A total of 3623 members of a national twin registry were administered structured diagnostic telephone interviews that included assessments of lifetime histories of MDD and AUD, and were mailed self-report personality questionnaires that assessed stress reactivity (SR) and behavioral control (CON). A series of biometric models were fitted to partition the proportion of covariance between MDD and AUD into SR and CON. Results A statistically significant proportion of the correlation between MDD and AUD was due to variance specific to SR (men = 0.31, women = 0.27) and CON (men = 0.20, women = 0.19). Further, genetic factors explained a large proportion of this correlation (0.63), with unique environmental factors explaining the rest. SR explained a significant proportion of the genetic (0.33) and environmental (0.23) overlap between MDD and AUD. In contrast, variance specific to CON accounted for genetic overlap (0.32), but not environmental overlap (0.004). In total, SR and CON accounted for approximately 70% of the genetic and 20% of the environmental covariation between MDD and AUD. Conclusions This is the first study to demonstrate that negative emotionality and behavioral control confer risk for the co-occurrence of MDD and AUD via genetic factors. These findings are consistent with the aims of NIMH's RDoC proposal to elucidate how transdiagnostic risk factors drive psychopathology

    A Study on the Parallelization of Terrain-Covering Ant Robots Simulations

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    Agent-based simulation is used as a tool for supporting (time-critical) decision making in differentiated contexts. Hence, techniques for speeding up the execution of agent-based models, such as Parallel Discrete Event Simulation (PDES), are of great relevance/benefit. On the other hand, parallelism entails that the final output provided by the simulator should closely match the one provided by a traditional sequential run. This is not obvious given that, for performance and efficiency reasons, parallel simulation engines do not allow the evaluation of global predicates on the simulation model evolution with arbitrary time-granularity along the simulation time-Axis. In this article we present a study on the effects of parallelization of agent-based simulations, focusing on complementary aspects such as performance and reliability of the provided simulation output. We target Terrain Covering Ant Robots (TCAR) simulations, which are useful in rescue scenarios to determine how many agents (i.e., robots) should be used to completely explore a certain terrain for possible victims within a given time. © 2014 Springer-Verlag Berlin Heidelberg
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