7,249 research outputs found

    A comparison of methods to evaluate energy expenditure of incubating wandering albatrosses

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    Measurements of incubation energetics can vary depending on the method used to measure metabolism of an incubating bird. Therefore, we evaluated the energy expenditure of six male and four female wandering albatrosses (Diomedea exulans Linnaeus) using doubly labeled water (DLW), the rate of mass loss, and estimates of metabolic water production derived from water influx rate (WIR). Incubation metabolic rates (IMR) determined with DLW ( 169 ± 21 kJ kg d SD) were significantly lower than estimates derived from mass loss ( 277 ± 46kJ kg d SD) and WIR ( males=289 ± 60 kJ kg d vs. females = 400 ± 69 kJ kg d SD). Estimates of IMR from f WIR were similar to IMR (305 ± 39 kJ kg d SD) determined by respirometry in a previous study, and IMR from DLW was similar to estimates based on heart rate (HR; 147 ± 26 kJ d SD) determined in another study. Ap- 147 26 plying the different measurements of IMR to construct an en-ergy budget, we estimate that a breeding pair of wandering albatrosses spends 124--234 MJ to incubate the egg for 78 d. Finally, IMRs determined with DLW and HR were similar

    On Optimality of Stepdown and Stepup Multiple Test Procedures

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    Consider the multiple testing problem of testing k null hypotheses, where the unknown family of distributions is assumed to satisfy a certain monotonicity assumption. Attention is restricted to procedures that control the familywise error rate in the strong sense and which satisfy a monotonicity condition. Under these assumptions, we prove certain maximin optimality results for some well-known stepdown and stepup procedures.Comment: Published at http://dx.doi.org/10.1214/009053605000000066 in the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

    Investigation of the Thermal Performance of Sierpinski Carpet Fractal Fins in a Natural Convection Environment

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    This experimental investigation studies the thermal performance of the first four iterations of the Sierpinski carpet pattern in a natural convection environment. This particular fractal geometry is promising in that it increases the available surface area for heat transfer while simultaneously decreasing the mass of the system. This makes it a potentially advantageous design for fins or heat sinks, especially in aerospace applications where minimizing mass of the system is essential. The thermal performance was evaluated by comparing the efficiency, effectiveness, and effectiveness per unit mass for each fractal iteration. The results indicate that efficiency decreases with each fractal iteration while effectiveness per unit mass increases with fractal iteration. The fourth iteration fractal fin was found to be approximately 10.7% more effective, 10.2% less efficient, and 77.3% more effective per unit mass when compared to a traditional straight rectangular fin of equal height, width, and thickness (the zeroth fractal iteration). Based on the results of a view factor analysis, thermal radiation was found to comprise an average of 42.3%, 39.7%, 39.1%, 38.5%, and 34.9% of the total heat transfer for the zeroth, first, second, third, and fourth fractal iteration fins, respectively. Therefore, the contribution of thermal radiation to the total heat transfer of the system cannot be neglected in future studies using this fractal pattern

    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
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