13,967 research outputs found
Wavelet-induced renormalization group for the Landau-Ginzburg model
The scale hierarchy of wavelets provides a natural frame for renormalization.
Expanding the order parameter of the Landau-Ginzburg/ model in a basis
of compact orthonormal wavelets explicitly exhibits the coupling between scales
that leads to non-trivial behavior. The locality properties of Daubechies'
wavelets enable us to derive the qualitative renormalization flow of the
Landau-Ginzburg model from Gaussian fluctuations in wavelet space.Comment: LATTICE99(Renormalization), LaTeX, 3 page
The phase-space structure of the Klein-Gordon field
The formalism based on the equal-time Wigner function of the two-point
correlation function for a quantized Klein--Gordon field is presented. The
notion of the gauge-invariant Wigner transform is introduced and equations for
the corresponding phase-space calculus are formulated. The equations of motion
governing the Wigner function of the Klein--Gordon field are derived. It is
shown that they lead to a relativistic transport equation with electric and
magnetic forces and quantum corrections. The governing equations are much
simpler than in the fermionic case which has been treated earlier. In addition
the newly developed formalism is applied towards the description of spontaneous
symmetry breakdown.Comment: 27 pages, LaTeX, UFTP 317/199
The 20 GHz spacecraft IMPATT solid state transmitter
The engineering development of a solid-state transmitter amplifier operating in the 20-GHz frequency range is described. This effort involved a multitude of disciplines including IMPATT device development, circulator design, multiple-diode circuit design, and amplifier integration and test. The objective was to develop a transmitter amplifier demonstrating the feasibility of providing an efficient, reliable, lightweight solid-state transmitter to be flown on a 30 to 20 GHz communication demonstration satellite. The work was done under contract from NASA/Lewis Research Center for a period of three years. The result was the development of a GaAs IMPACT diode amplifier capable of an 11-W CW output power and a 2-dB bandwidth of 300 MHz. GaAs IMPATT diodes incorporating diamond heatsink and double-Read doping profile capable of 5.3-W CW oscillator output power and 15.5% efficiency were developed. Up to 19% efficiency was also observed for an output power level of 4.4 W. High performance circulators with a 0.2 dB inserting loss and bandwidth of 5 GHz have also been developed. These represent a significant advance in both device and power combiner circuit technologies in K-band frequencies
U(1) flux tube profiles from Hamiltonian lattice gauge theory using a random walk ground-state projector
We use a self-guided random walk to solve the ground-state problem of
Hamiltonian U(1) pure gauge theory in 2+1 dimensions in the string sector. By
making use of the electric-field representation, we argue that the spatial
distribution of the electric field can be more easily measured than in ordinary
Monte Carlo simulations.Comment: 3 pages, contribution to Lattice 94, uuencoded compressed Postscrip
Erratum: Luminosity function, sizes and FR dichotomy of radio-loud AGN
This erratum corrects a number of formulae containing mistakes in the paper
'Luminosity function, sizes and FR dichotomy of radio-loud AGN', 2007, MNRAS,
v. 381, p.1548. The corrections do not alter any of the conclusions in the
original paper.Comment: single page, no figures, erratum to MNRAS, 2007, v. 381, p. 154
QCD on \alpha-Clusters
It is shown that the 21264 Alpha processor can reach about 20% sustained
efficiency for the inversion of the Wilson-Dirac operator. Since fast ethernet
is not sufficient to get balancing between computation and communication on
reasonable lattice- and system-sizes, an interconnection using Myrinet is
discussed. We find a price/performance ratio comparable with state-of-the-art
SIMD-systems for lattice QCD.Comment: LATTICE99(machines), 3 page
Creating Accessible Instruction
A capstone submitted in partial fulfillment of the requirements for the degree of Doctor of Education in the Ernst and Sara Lane Volgenau College of Education at Morehead State University by Cassandra C. Best on April 6, 2021
Wavelets as a variational basis of the XY model
We use Daubechies' orthonormal compact wavelets as a variational basis for
the model in two and three dimensions. Assuming that the fluctuations of
the wavelet coefficients are Gaussian and uncorrelated, minimization of the
free energy yields the fluctuation strength of wavelet coefficients at
different scales, from which observables can be computed. This model is able to
describe the low-temperature phase and makes a prediction about the phase
transition temperature.Comment: 3 pages, postscript. Contribution to the Lattice 93 workshop (Dallas,
Texas, October 1993
HgSe, a highly electronegative stable metallic contact for semiconductor devices
Schottky barriers formed by the highly electronegative substance HgSe on n-ZnS and on n-ZnSe have been characterized by capacitance-voltage and photoresponse measurements. The barriers are about 0.5 eV greater than Au barriers on these n-type substrates. HgSe contacts are stable under ambient conditions and are easily fabricated, making them attractive for device use
VLT spectropolarimetry of two powerful radio galaxies at z~1.4: UV continuum, emission-line properties and the nature of high-redshift dust
(Abridged) Deep VLT spectropolarimetric observations are presented for two
powerful radio galaxies, 0850-206 and 1303+091. These observations cover the
rest-frame wavelength range ~ 1450 - 3750 A. New radio observations and
continuum images of the same sources are also presented. These galaxies are the
first two observed from a complete sample of nine radio sources with redshifts
in the range 1.3 < z < 1.5 (selected from the equatorial sample of powerful
radio sources of Best, Rottgering & Lehnert), as part of a project aimed to
investigate the multi-component nature of the UV continuum in radio galaxies
and any variations of the continuum properties with the radio source age.
The larger radio source of the two, 0850-206, presents a high continuum
fractional polarization, averaging 17% across the observed wavelength range and
reaching 24% at rest-frame wavelengths of <2000 A. The smaller radio source,
1303+091, shows a lower continuum polarization, averaging 8% and rising to 11%
for rest-frame wavelengths >3000 A. For both galaxies, the position angle of
the electric vector is generally constant with wavelength and within ~15
degrees of perpendicular to the radio axis. Both their total flux spectra and
polarized flux spectra reveal the 2200 A dust feature, and comparison with dust
scattering models suggests that the composition of the dust in these galaxies
is similar to that of Galactic dust. In 0850-206, scattered quasar radiation
dominates the UV continuum emission, with the nebular continuum accounting for
no more than ~22% and no requirement for any additional emission component such
as emission from young stars. By contrast, in 1303+091, unpolarized radiation
could be a major constituent of the UV continuum emission, with starlight
accounting for up to ~50% and the nebular continuum accounting for ~11%.Comment: 20 pages, including 14 figures. MNRAS accepte
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