10,336 research outputs found

    Angular Distribution Of Decay Electrons From The 6P Resonance Excitations In Xenon

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    Angular distributions for the electrons produced by the decay of the 4d--\u3e6p excitations in xenon have been measured using an undulator radiation source. The resolution employed in the experiment has allowed us to derive separate beta values for features which had not been isolated previously, as well as to determine beta values for previously unreported lines. Comparison is made between existing experimental and theoretical results

    Large Extra Dimensions, Sterile neutrinos and Solar Neutrino Data

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    Solar, atmospheric and LSND neutrino oscillation results require a light sterile neutrino, νB\nu_B, which can exist in the bulk of extra dimensions. Solar νe\nu_e, confined to the brane, can oscillate in the vacuum to the zero mode of νB\nu_B and via successive MSW transitions to Kaluza-Klein states of νB\nu_B. This new way to fit solar data is provided by both low and intermediate string scale models. From average rates seen in the three types of solar experiments, the Super-Kamiokande spectrum is predicted with 73% probability, but dips characteristic of the 0.06 mm extra dimension should be seen in the SNO spectrum.Comment: 4 pages, 2 figure

    Cosmological milestones and energy conditions

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    Until recently, the physically relevant singularities occurring in FRW cosmologies had traditionally been thought to be limited to the "big bang", and possibly a "big crunch". However, over the last few years, the zoo of cosmological singularities considered in the literature has become considerably more extensive, with "big rips" and "sudden singularities" added to the mix, as well as renewed interest in non-singular cosmological events such as "bounces" and "turnarounds". In this talk, we present an extensive catalogue of such cosmological milestones, both at the kinematical and dynamical level. First, using generalized power series, purely kinematical definitions of these cosmological events are provided in terms of the behaviour of the scale factor a(t). The notion of a "scale-factor singularity" is defined, and its relation to curvature singularities (polynomial and differential) is explored. Second, dynamical information is extracted by using the Friedmann equations (without assuming even the existence of any equation of state) to place constraints on whether or not the classical energy conditions are satisfied at the cosmological milestones. Since the classification is extremely general, and modulo certain technical assumptions complete, the corresponding results are to a high degree model-independent.Comment: 8 pages, 1 table, conference proceedings for NEB XII conference in Nafplio, Greec

    A haptic-enabled multimodal interface for the planning of hip arthroplasty

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    Multimodal environments help fuse a diverse range of sensory modalities, which is particularly important when integrating the complex data involved in surgical preoperative planning. The authors apply a multimodal interface for preoperative planning of hip arthroplasty with a user interface that integrates immersive stereo displays and haptic modalities. This article overviews this multimodal application framework and discusses the benefits of incorporating the haptic modality in this area

    High resolution, low temperature photoabsorption cross-section of C2H2 with application to Saturn's atmosphere

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    New laboratory observations of the VUV absorption cross-section of C2H2, obtained under physical conditions approximating stratospheres of the giant planets, were combined with IUE observations of the albedo of Saturn, for which improved data reduction techniques have been used, to produce new models for that atmosphere. When the effects of C2H2 absorption are accounted for, additional absorption by other molecules is required. The best-fitting model also includes absorption by PH3, H2O, C2H6 and CH4. A small residual disagreement near 1600 A suggests that an additional trace species may be required to complete the model

    K-Shell Auger Spectrum Of Atomic Oxygen

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    We have observed the K-shell Auger spectrum in atomic oxygen. A total of ten transitions originating from the decay of the 4P and 2P states of the O+(1s-1) ion are identified and assigned to final states of the O2+ ion. Relative intensities for each of these transitions are obtained, allowing the extraction of the dependence of the Auger decay on the multiplet structure in both the initial and final states of this basic open-shell atom

    The Shape and Scale of Galactic Rotation from Cepheid Kinematics

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    A catalog of Cepheid variables is used to probe the kinematics of the Galactic disk. Radial velocities are measured for eight distant Cepheids toward l = 300; these new Cepheids provide a particularly good constraint on the distance to the Galactic center, R_0. We model the disk with both an axisymmetric rotation curve and one with a weak elliptical component, and find evidence for an ellipticity of 0.043 +/- 0.016 near the Sun. Using these models, we derive R_0 = 7.66 +/- 0.32 kpc and v_circ = 237 +/- 12 km/s. The distance to the Galactic center agrees well with recent determinations from the distribution of RR Lyrae variables, and disfavors most models with large ellipticities at the solar orbit.Comment: 36 pages, LaTeX, 10 figure

    A fluorescent mutant of the phosphorus-solubilizing fungus Penicillium bilaiae to image rhizosphere growth

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    Non-Peer ReviewedNovozymes manufactures and markets a phosphate inoculant, JumpStart®, based on the phosphorus-solubilizing fungus Penicillium bilaiae. We are developing a mutant of this fungus that expresses the DsRed-Express fluorescent protein, which will be used as a research tool to allow us to see where and how P. bilaiae interacts with plant roots
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