2,265 research outputs found

    Item program manual, Fortran IV version

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    Orbit calculation using Encke perturbation method and Fortran IV programmin

    ERBE/NOAA-9 observations for the FIRE/SRB Wisconsin experiment region from October 14 through October 31, 1986

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    Tables are presented which show ERBE/NOAA-9 radiances, resolution size, and pixel location for the FIRE/SRB Wisconsin experiment region from October 1 through October 31, l986. Also presented is an analysis of the ERBE point spread function used to estimate pixel resolution size for the scanner instrument

    Interplanetary trajectory Encke method FORTRAN program manual for the IBM system/360

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    Interplanetary trajectory Encke method FORTRAN program manual for IBM 360 compute

    Sub-Poissonian atom number fluctuations by three-body loss in mesoscopic ensembles

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    We show that three-body loss of trapped atoms leads to sub-Poissonian atom number fluctuations. We prepare hundreds of dense ultracold ensembles in an array of magnetic microtraps which undergo rapid three-body decay. The shot-to-shot fluctuations of the number of atoms per trap are sub-Poissonian, for ensembles comprising 50--300 atoms. The measured relative variance or Fano factor F=0.53±0.22F=0.53\pm 0.22 agrees very well with the prediction by an analytic theory (F=3/5F=3/5) and numerical calculations. These results will facilitate studies of quantum information science with mesoscopic ensembles.Comment: 4 pages, 3 figure

    Improved detection of small atom numbers through image processing

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    We demonstrate improved detection of small trapped atomic ensembles through advanced post-processing and optimal analysis of absorption images. A fringe removal algorithm reduces imaging noise to the fundamental photon-shot-noise level and proves beneficial even in the absence of fringes. A maximum-likelihood estimator is then derived for optimal atom-number estimation and is applied to real experimental data to measure the population differences and intrinsic atom shot-noise between spatially separated ensembles each comprising between 10 and 2000 atoms. The combined techniques improve our signal-to-noise by a factor of 3, to a minimum resolvable population difference of 17 atoms, close to our ultimate detection limit.Comment: 4 pages, 3 figure

    Investigation of effects of background water on upwelled reflectance spectra and techniques for analysis of dilute primary-treated sewage sludge

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    In an effort to improve understanding of the effects of variations in background water on reflectance spectra, laboratory tests were conducted with various concentrations of sewage sludge diluted with several types of background water. The results from these tests indicate that reflectance spectra for sewage-sludge mixtures are dependent upon the reflectance of the background water. Both the ratio of sewage-sludge reflectance to background-water reflectance and the ratio of the difference in reflectance to background-water reflectance show spectral variations for different turbid background waters. The difference in reflectance is the only parameter considered

    Random copying in space

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    Random copying is a simple model for population dynamics in the absence of selection, and has been applied to both biological and cultural evolution. In this work, we investigate the effect that spatial structure has on the dynamics. We focus in particular on how a measure of the diversity in the population changes over time. We show that even when the vast majority of a population's history may be well-described by a spatially-unstructured model, spatial structure may nevertheless affect the expected level of diversity seen at a local scale. We demonstrate this phenomenon explicitly by examining the random copying process on small-world networks, and use our results to comment on the use of simple random-copying models in an empirical context.Comment: 26 pages, 11 figures. Based on invited talk at AHRC CECD Conference on "Cultural Evolution in Spatially Structured Populations" at UCL, September 2010. To appear in ACS - Advances in Complex System

    Asymmetric double-well potential for single atom interferometry

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    We consider the evolution of a single-atom wavefunction in a time-dependent double-well interferometer in the presence of a spatially asymmetric potential. We examine a case where a single trapping potential is split into an asymmetric double well and then recombined again. The interferometer involves a measurement of the first excited state population as a sensitive measure of the asymmetric potential. Based on a two-mode approximation a Bloch vector model provides a simple and satisfactory description of the dynamical evolution. We discuss the roles of adiabaticity and asymmetry in the double-well interferometer. The Bloch model allows us to account for the effects of asymmetry on the excited state population throughout the interferometric process and to choose the appropriate splitting, holding and recombination periods in order to maximize the output signal. We also compare the outcomes of the Bloch vector model with the results of numerical simulations of the multi-state time-dependent Schroedinger equation.Comment: 9 pages, 6 figure

    Interplanetary Trajectories, Encke Method (ITEM)

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    Modified program has been developed using improved variation of Encke method which avoids accumulation of round-off errors and avoids numerical ambiguities arising from near-circular orbits of low inclination. Variety of interplanetary trajectory problems can be computed with maximum accuracy and efficiency

    Absolute Intensities of the Discrete and Continuous Absorption Bands of Oxygen Gas at 1.26 and 1.065 µ and the Radiative Lifetime of the 1Δg State of Oxygen

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    Laboratory measurements have been made of the absolute intensities of the discrete-line absorption band at 1.26 µ, and of the continuous bands at 1.26 and 1.065 µ in oxygen gas at pressures up to 4.3 atm. It has been shown that discrete and continuous absorptions are quite independent features, the one being a measure of the intrinsic transition probability in isolated molecules, the other of its enhancement in collision complexes. In the former the lines show significant pressure broadening, but the integral molecular absorption coefficients are constant; in the latter they are proportional to pressure and continuous absorption dominates in the 1.26-µ region at about ½ atm oxygen pressure.The radiative half-life of isolated 1Δg oxygen molecules is estimated to be 45 min, and the effect of gas pressure on the rate of decay has been predicted
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