43,037 research outputs found
Analysis of coronal line profiles Quarterly report, 1 Jun. - 31 Aug. 1968
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
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
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
High altitude measurement to determine ratio of deuterium to hydrogen in solar atmosphere - Fabry-Perot interferomete
Lunar exploration for water deposits by electrical methods
Lunar exploration for water deposits by electrical method
Renormalized Path Integral in Quantum Mechanics
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
We obtain a bilocal classical field theory as the large 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 limit of the spectrum of the chiral
Gross--Neveu model.Comment: Tex, 18 pages, no figure
Renormalized Contact Potential in Two Dimensions
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
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 1.1 \AA for every
incident 300 keV e/\AA. The induced motion leads to an optimal
exposure with 300 keV electrons of 4.0 e/\AA 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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