42,464 research outputs found

    Analysis of coronal line profiles Quarterly report, 1 Jun. - 31 Aug. 1968

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    Coronal Fe 14 emission data reduced to line profile

    A High Altitude Measurement to Determine the Ratio of Deuterium to Hydrogen in the Solar Atmosphere Final Report, 1 Jun. 1965 - 30 Mar. 1966

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    Fabry-Perot interferometers used to determine ratio of deuterium to hydrogen in solar atmospher

    A high altitude measurement to determine the ratio of deuterium to hydrogen in the solar atmosphere Quarterly status report, 1 Dec. 1965 - 28 Feb. 1966

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    Optical systems for high altitude measurements to determine deuterium-hydrogen ratio in solar photosphere by recording profiles of Fraunhofer line

    A high altitude measurement to determine the ratio of deuterium to hydrogen in the solar atmosphere Quarterly status report, 1 Jun. - 31 Aug. 1965

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    High altitude measurement to determine ratio of deuterium to hydrogen in solar atmosphere - Fabry-Perot interferomete

    Lunar exploration for water deposits by electrical methods

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    Lunar exploration for water deposits by electrical method

    Renormalized Path Integral in Quantum Mechanics

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    We obtain direct, finite, descriptions of a renormalized quantum mechanical system with no reference to ultraviolet cutoffs and running coupling constants, in both the Hamiltonian and path integral pictures. The path integral description requires a modification to the Wiener measure on continuous paths that describes an unusual diffusion process wherein colliding particles occasionally stick together for a random interval of time before going their separate ways.Comment: 13 pgs, plain TEX fil

    Solitons in a Bilocal Field Theory

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    We obtain a bilocal classical field theory as the large NN limit of the chiral Gross--Neveu (or non--abelian Thirring) model. Exact classical solutions that describe topological solitons are obtained. It is shown that their mass spectrum agrees with the large NN limit of the spectrum of the chiral Gross--Neveu model.Comment: Tex, 18 pages, no figure

    Renormalized Contact Potential in Two Dimensions

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    We obtain for the attractive Dirac delta-function potential in two-dimensional quantum mechanics a renormalized formulation that avoids reference to a cutoff and running coupling constant. Dimensional transmutation is carried out before attempting to solve the system, and leads to an interesting eigenvalue problem in N-2 degrees of freedom (in the center of momentum frame) when there are N particles. The effective Hamiltonian for N-2 particles has a nonlocal attractive interaction, and the Schrodinger equation becomes an eigenvalue problem for the logarithm of this Hamiltonian. The 3-body case is examined in detail, and in this case a variational estimate of the ground-state energy is given.Comment: Plain Te

    Thon rings from amorphous ice and implications of beam-induced Brownian motion in single particle electron cryo-microscopy

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    We have recorded dose-fractionated electron cryo-microscope images of thin films of pure flash-frozen amorphous ice and pre-irradiated amorphous carbon on a Falcon~II direct electron detector using 300 keV electrons. We observe Thon rings \cite{Thon1966} in both the power spectrum of the summed frames and the sum of power spectra from the individual frames. The Thon rings from amorphous carbon images are always more visible in the power spectrum of the summed frames whereas those of amorphous ice are more visible in the sum of power spectra from the individual frames. This difference indicates that while pre-irradiated carbon behaves like a solid during the exposure, amorphous ice behaves like a fluid with the individual water molecules undergoing beam-induced motion. Using the measured variation in the power spectra amplitude with number of electrons per image we deduce that water molecules are randomly displaced by mean squared distance of ∼\sim 1.1 \AA2^{2} for every incident 300 keV e−^{-}/\AA2^2. The induced motion leads to an optimal exposure with 300 keV electrons of 4.0 e−^{-}/\AA2^2 per image with which to see Thon rings centred around the strong 3.7{\AA} scattering peak from amorphous ice. The beam-induced movement of the water molecules generates pseudo-Brownian motion of embedded macromolecules. The resulting blurring of single particle images contributes an additional term, on top of that from radiation damage, to the minimum achievable B-factor for macromolecular structure determination.Comment: 11 pages, 6 figures, Supplementary information 6 pages with 5 figure
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