12,137 research outputs found
Evolution of domain wall networks: the PRS algorithm
The Press-Ryden-Spergel (PRS) algorithm is a modification to the field theory
equations of motion, parametrized by two parameters ( and ),
implemented in numerical simulations of cosmological domain wall networks, in
order to ensure a fixed comoving resolution. In this paper we explicitly
demonstrate that the PRS algorithm provides the correct domain wall dynamics in
-dimensional Friedmann-Robertson-Walker (FRW) universes if
, fully validating its use in numerical studies of cosmic
domain evolution. We further show that this result is valid for generic thin
featureless domain walls, independently of the Lagrangian of the model.Comment: 4 page
Congenital cystic adenomatoid malformation of the lung or congenital pulmonary airway malformation
The cystic adenomatoid malformation of the lung is an hamartomatous lesion, easily identifiable by its morphology through the application of Stocker's et al (1977) classification (type 1, 2 and 3) and also following the criteria of Yousem, to understand the five types dependent on the level of malformation in the airway and lung. The three morphological types described by Stocker were identified in 6 cases of the archive of the Department of Pathology of Coimbra's University Hospital, studied morphologically by the use of Movat's pentachromic stain and the application of the antibody anti-CK7 and anti-body anti-TTF1. In the three morphological types the elastic alveolar net is absent. The CK7 identifies the epithelial distribution and is useful to evaluate the extension of the inflammatory lesion. The antibody anti-TTF1, apparently absent in type 3 cases, is easily identified in type 1 and 2 cases and overexpressed in inflammatory areas. It seems that the absence of cells identified by the antibody anti-TTF1 prevents overdiagnosing of type 4 in Yousem's classification of congenital pulmonary airway malformation (CPAM)
Graviton resonances on two-field thick branes
This work presents new results about the graviton massive spectrum in
two-field thick branes. Analyzing the massive spectra with a relative
probability method we have firstly showed the presence of resonance structures
and obtained a connection between the thickness of the defect and the lifetimes
of such resonances. We obtain another interesting results considering the
degenerate Bloch brane solutions. In these thick brane models, we have the
emergence of a splitting effect controlled by a degeneracy parameter. When the
degeneracy constant tends to a critical value, we have found massive resonances
to the gravitational field indicating the existence of modes highly coupled to
the brane. We also discussed the influence of the brane splitting effect over
the resonance lifetimes.Comment: 15 pages, 8 figure
Exponentially Localized Magnetic Fields for Single-Spin Quantum Logic Gates
An infinite array of parallel current-carrying wires is known, from the field
of neutral particle optics, to produce an exponentially localized magnetic
field when the current direction is antiparallel in adjacent wires. We show
that a finite array of several tens of superconducting Nb nanowires can produce
a peak magnetic field of 10mT that decays by a factor of 10^4 over a length
scale of 500nm. Such an array is readily manufacturable with current
technology, and is compatible with both semiconductor and superconducting
quantum computer architectures. A series of such arrays can be used to
individually address single single-spin or flux qubits spaced as little as
100nm apart, and can lead to quantum logic gate times of 5ns.Comment: 5 pages, incl. 4 figure
Response to tilted magnetic fields in Bi2Sr2CaCu2O8 with columnar defects: Evidence for transverse Meissner effect
The transverse Meissner effect (TME) in the highly layered superconductor
Bi2Sr2CaCu2O(8+y) with columnar defects is investigated by transport
measurements. We present detailed evidence for the persistence of the
Bose-glass phase when H is tilted at an angle theta < theta_c (T) away from the
column direction: (i) the variable-range vortex hopping process for low
currents crosses over to the half-loops regime for high currents; (ii) in both
regimes near theta_c(T) the energy barriers vanish linearly with tan(theta) ;
(iii) the transition temperature is governed by T_{BG}(0) -T_{BG}(theta) sim
|tan(theta)|^{1/\nu_{\perp}} with \nu_{\perp}=1.0 +/- 0.1. Furthermore, above
the transition as theta->\theta_c+, moving kink chains consistent with a
commensurate-incommensurate transition scenario are observed. These results
thereby clearly show the existence of the TME for theta < theta_c(T).Comment: 4 pages, RevTeX, 5 EPS figure
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