5,657 research outputs found

    Availability and Use of Water in Nebraska, 1970

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    Availability and Use of Water in Nebraska, 1970

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    Corticosterone and foraging behaviour in a pelagic seabird

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    Because endocrine mechanisms are thought to mediate behavioral responses to changes in the environment, examining these mechanisms is essential for understanding how long-lived seabirds adjust their foraging decisions to contrasting environmental conditions in order to maximize their fitness. In this context, the hormone corticosterone (CORT) deserves specific attention because of its major connections with locomotor activities. We examined for the first time the relationships between individual CORT levels and measurements of foraging success and behavior using satellite tracking and blood sampling from wandering albatrosses (Diomedea exulans) before (pretrip CORT levels) and after (posttrip CORT levels) foraging trips during the incubation period. Plasma CORT levels decreased after a foraging trip, and the level of posttrip CORT was negatively correlated with individual foraging success, calculated as total mass gain over a foraging trip. Pretrip CORT levels were not linked to time spent at sea but were positively correlated with daily distance traveled and maximum range at sea. In this study, we were able to highlight the sensitivity of CORT levels to variation in energy intake, and we showed for the first time that individual CORT levels can be explained by variation in foraging success. Relationships between pretrip CORT levels and daily distance traveled and maximum range were independent of pretrip body mass, suggesting that slight elevations in pretrip CORT levels might facilitate locomotor activity. However, because both foraging behavior and pretrip CORT levels could be affected by individual quality, future experimental studies including manipulation of CORT levels are needed to test whether CORT can mediate foraging decisions according to foraging conditions

    Photoionization Rates of Cs Rydberg Atoms in a 1064 nm Far Off-Resonance Trap

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    Experimental measurements of photoionization rates of nD5/2nD_{5/2} Rydberg states of Cs (50≤n≤7550 \leq n \leq 75) in a 1064 nm far off-resonance dipole trap are presented. The photoionization rates are obtained by measuring the lifetimes of Rydberg atoms produced inside of a 1064 nm far off-resonance trap and comparing the lifetimes to corresponding control experiments in a magneto-optical trap. Experimental results for the control experiments agree with recent theoretical predictions for Rydberg state lifetimes and measured photoionization rates are in agreement with transition rates calculated from a model potential.Comment: 12 pages, 4 figure

    Availability and Use of Water in Nebraska, 1975

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    Feasibility study of full-reactor gas core demonstration test

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    Separate studies of nuclear criticality, flow patterns, and thermodynamics for the gas core reactor concept have all given positive indications of its feasibility. However, before serious design for a full scale gas core application can be made, feasibility must be shown for operation with full interaction of the nuclear, thermal, and hydraulic effects. A minimum sized, and hence minimum expense, test arrangement is considered for a full gas core configuration. It is shown that the hydrogen coolant scattering effects dominate the nuclear considerations at elevated temperatures. A cavity diameter of somewhat larger than 4 ft (122 cm) will be needed if temperatures high enough to vaporize uranium are to be achieved

    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
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