51,397 research outputs found

    Apparatus for assembling space structure

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    An apparatus for producing a structure in outer space from rolls of prepunched ribbon or sheet material that are transported from the earth to the apparatus located in outer space is described. The apparatus spins the space structure similar to a spider spinning a web utilizing the prepunched ribbon material. The prepunched ribbon material is fed through the apparatus and is shaped into a predetermined channel-shaped configuration. Trusses are punched out of the ribbon and are bent downwardly and attached to a track which normally is a previously laid sheet of material. The size of the overall space structure may be increased by merely attaching an additional roll of sheet material to the apparatus

    Lowest Order Constrained Variational Calculation of the Polarized Nuclear Matter with the Modern AV18AV_{18} Potential

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    The lowest order constrained variational method is applied to calculate the polarized symmetrical nuclear matter properties with the modern AV18AV_{18} potential performing microscopic calculations. Results based on the consideration of magnetic properties show no sign of phase transition to a ferromagnetic phase.Comment: 19 pages, 6 figure

    The Distances of SNR W41 and overlapping HII regions

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    New HI images from the VLA Galactic Plane Survey show prominent absorption features associated with the supernovae remnant G23.3-0.3 (SNR W41). We highlight the HI absorption spectra and the 13^{13}CO emission spectra of eight small regions on the face of W41, including four HII regions, three non-thermal emission regions and one unclassified region. The maximum velocity of absorption for W41 is 78±\pm2 km/s and the CO cloud at radial velocity 95±\pm5 km/s is behind W41. Because an extended TeV source, a diffuse X-ray enhancement and a large molecular cloud at radial velocity 77±\pm5 km/s are also projected at the center of W41, these yield the kinematic distance of 3.9 to 4.5 kpc for W41. For HII regions, our analyses reveal that both G23.42-0.21 and G23.07+0.25 are at the far kinematic distances (∼\sim9.9 kpc and ∼\sim 10.6 kpc respectively) of their recombination-line velocities (103±\pm0.5 km/s and 89.6±\pm2.1 km/s respectively), G23.07-0.37 is at the near kinematic distance (4.4±\pm0.3 kpc) of its recombination-line velocity (82.7±\pm2.0 km/s), and G23.27-0.27 is probably at the near kinematic distance (4.1±\pm0.3 kpc) of its recombination-line velocity (76.1±\pm0.6 km/s).Comment: 11 pages, 3 figs., 2 tables, accepted by A

    Effect of polarization on superfluidity in low density neutron matter

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    It is shown that, contrary to an earlier estimate, the polarizability of the neutron medium tends to suppress rather than enhance the isotropic energy gap in low-density neutron-star matter

    A Brownian particle in a microscopic periodic potential

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    We study a model for a massive test particle in a microscopic periodic potential and interacting with a reservoir of light particles. In the regime considered, the fluctuations in the test particle's momentum resulting from collisions typically outweigh the shifts in momentum generated by the periodic force, and so the force is effectively a perturbative contribution. The mathematical starting point is an idealized reduced dynamics for the test particle given by a linear Boltzmann equation. In the limit that the mass ratio of a single reservoir particle to the test particle tends to zero, we show that there is convergence to the Ornstein-Uhlenbeck process under the standard normalizations for the test particle variables. Our analysis is primarily directed towards bounding the perturbative effect of the periodic potential on the particle's momentum.Comment: 60 pages. We reorganized the article and made a few simplifications of the conten

    Ortho-para transition rate in μ\mu-molecular hydrogen and the proton's induced pseudoscalar coupling gpg_p

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    We report a measurement of the ortho-para transition rate in the pμ\mup molecule. The experiment was conducted at TRIUMF via the measurement of the time dependence of the 5.2 MeV neutrons from muon capture in liquid hydrogen. The measurement yielded an ortho-para rate Λop=(11.1±1.7±0.60.9)×104\Lambda_{op} = (11.1 \pm 1.7 \pm^{0.9}_{0.6}) \times 10^4 s−1^{-1} that is substantially larger than the earlier result of Bardin {\it et al.} We discuss the striking implications for the proton's induced pseudoscalar coupling gpg_p.Comment: 4 pages, 3 figures, submitted to Phys. Rev. Let
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