6,250 research outputs found

    Meteoroid hazards in deep space Final report

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    Design and development of Sisyphus meteoroid detection system for interplanetary spacecraf

    High pressure compressor component performance report

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    A compressor optimization study defined a 10 stage configuration with a 22.6:1 pressure ratio, an adiabatic efficiency goal of 86.1%, and a polytropic efficiency of 90.6%; the corrected airflow is 53.5 kg/s. Subsequent component testing included three full scale tests: a six stage rig test, a 10 stage rig test, and another 10 stage rig test completed in the second quarter of 1982. Information from these tests is used to select the configuration for a core engine test and an integrated core/low spool test. The test results will also provide data base for the flight propulsion system. The results of the test series with both aerodynamic and mechanical performance of each compressor build are presented. The second 10 stage compressor adiabatic efficiency was 0.848 at a cruise operating point versus a test goal of 0.846

    Safety, the Preface Paradox and Possible Worlds Semantics

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    This paper contains an argument to the effect that possible worlds semantics renders semantic knowledge impossible, no matter what ontological interpretation is given to possible worlds. The essential contention made is that possible worlds semantic knowledge is unsafe and this is shown by a parallel with the preface paradox

    Observation of blue-shifted ultralong-range Cs2_{2} Rydberg molecules

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    We observe ultralong-range blue-shifted Cs2_{2} molecular states near ns1/2ns_{1/2} Rydberg states in an optical dipole trap, where 31≤n≤3431\leq n\leq34. The accidental near degeneracy of (n−4)l(n-4)l and nsns Rydberg states for l>2l>2 in Cs, due to the small fractional nsns quantum defect, leads to non-adiabatic coupling among these states, producing potential wells above the nsns thresholds. Two important consequences of admixing high angular momentum states with nsns states are the formation of large permanent dipole moments, ∼15−100 \sim 15-100\,Debye, and accessibility of these states via two-photon association. The observed states are in excellent agreement with theory. Both projections of the total angular momentum on the internuclear axis are visible in the experiment

    Using the theory of planned behavior to predict gambling behavior

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    Gambling is an important public health concern. To better understand gambling behavior, we conducted a classroom-based survey that assessed the role of the theory of planned behavior (TPB; i.e., intentions, subjective norms, perceived behavioral control, and attitudes) in past year gambling and gambling frequency among college students. Results from this research support the utility of the TPB to explain gambling behavior in this population. Specifically, in TPB models to predict gambling behavior, friend and family subjective norms and perceived behavioral control predicted past year gambling and friend and family subjective norms, attitudes and perceived behavioral control predicted gambling frequency. Intention to gamble mediated these relationships. These findings suggest that college responsible gambling efforts should consider targeting misperceptions of approval regarding gambling behavior (i.e., subjective norms), personal approval of gambling behavior (i.e., attitudes), and perceived behavioral control to better manage gambling behavior in various situations

    Niche partitioning among and within sympatric tropical seabirds revealed by stable isotope analysis

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    The low productivity and unpredictable nature of resources in tropical waters would appear to make resource partitioning among predators difficult. Yet, stable isotope data from the present study suggest that substantial resource partitioning occurs among tropical seabird communities, both between and within species. In the present study, we compared δ13C and δ15N levels among 8 sympatric tropical seabird species. For a subset of these species, we also examined isotopic levels across years, breeding periods, and sexes. When breeding and non-breeding periods were both considered, we found that all species occupied distinct isotopic niches across at least one time period. Resource partitioning by age (within the same year) and year studied (for birds of the same age), within species was observed in all the species we examined. However, niche separation by sex appeared to be relatively uncommon even in sexually dimorphic species. As a group, seabirds were isotopically distinct from other marine predators. There was a strong correlation between both body mass and wing loading ratios and foraging area, as evaluated using δ13C levels. Cumulatively, the isotopic patterns observed are consistent with diet-based surveys of resource partitioning during the breeding period. Importantly, these data provide additional evidence to suggest that substantial niche partitioning among tropical seabird species persists even during non-breeding periods in open ocean environments, when direct diet-based surveys are difficult to conduct
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