26,754 research outputs found
Plastic Deformation of 2D Crumpled Wires
When a single long piece of elastic wire is injected trough channels into a
confining two-dimensional cavity, a complex structure of hierarchical loops is
formed. In the limit of maximum packing density, these structures are described
by several scaling laws. In this paper it is investigated this packing process
but using plastic wires which give origin to completely irreversible structures
of different morphology. In particular, it is studied experimentally the
plastic deformation from circular to oblate configurations of crumpled wires,
obtained by the application of an axial strain. Among other things, it is shown
that in spite of plasticity, irreversibility, and very large deformations,
scaling is still observed.Comment: 5 pages, 6 figure
Classical Integrable N=1 and Super Sinh-Gordon Models with Jump Defects
The structure of integrable field theories in the presence of jump defects is
discussed in terms of boundary functions under the Lagrangian formalism.
Explicit examples of bosonic and fermionic theories are considered. In
particular, the boundary functions for the N=1 and N=2 super sinh-Gordon models
are constructed and shown to generate the Backlund transformations for its
soliton solutions. As a new and interesting example, a solution with an
incoming boson and an outgoing fermion for the N=1 case is presented. The
resulting integrable models are shown to be invariant under supersymmetric
transformation.Comment: talk presented at the V International Symposium on Quantum Theory and
Symmetries, Valladolid, Spain, July 22-28,200
Cognition and Behavior in Two-Person Guessing Games: An Experimental Study
This paper reports experiments that elicit subjects' initial responses to 16 dominancesolvable two-person guessing games. The structure is publicly announced except for varying payoff parameters, to which subjects are given free access, game by game, through an interface that records their information searches. Varying the parameters allows strong separation of the behavior implied by leading decision rules and makes monitoring search a powerful tool for studying cognition. Many subjects' decisions and searches show clearly that they understand the games and seek to maximize their payoffs, but have boundedly rational models of others' decisions, which lead to systematic deviations from equilibrium.
Integrable Field Theories with Defects
The structure of integrable field theories in the presence of defects is
discussed in terms of boundary functions under the Lagrangian formalism.
Explicit examples of bosonic and fermionic theories are considered. In
particular, the boundary functions for the super sinh-Gordon model is
constructed and shown to generate the Backlund transformations for its soliton
solutions.Comment: talk presented at the XVth International Colloquium on Integrable
Systems and Quantum Symmetries, to appear in Czechoslovak Journal of Physics
(2006
Structural properties of crumpled cream layers
The cream layer is a complex heterogeneous material of biological origin
which forms spontaneously at the air-milk interface. Here, it is studied the
crumpling of a single cream layer packing under its own weight at room
temperature in three-dimensional space. The structure obtained in these
circumstances has low volume fraction and anomalous fractal dimensions. Direct
means and noninvasive NMR imaging technique are used to investigate the
internal and external structure of these systems.Comment: 9 pages, 4 figures, accepted in J. Phys. D: Appl. Phy
On the properties of the interstellar medium in extremely metal-poor blue compact dwarf galaxies: GMOS-IFU spectroscopy and SDSS photometry of the double-knot galaxy HS 2236+1344
The main goal of this study is to carry out a spatially resolved
investigation of the warm interstellar medium (ISM) in the extremely metal-poor
Blue Compact Dwarf (BCD) galaxy HS 2236+1344. Special emphasis is laid on the
analysis of the spatial distribution of chemical abundances, emission-line
ratios and kinematics of the ISM, and to the recent star-forming activity in
this galaxy. This study is based on optical integral field unit spectroscopy
data from Gemini Multi-Object Spectrograph at the Gemini North telescope and
archival Sloan Digital Sky Survey images. The data were obtained in two
different positions across the galaxy, obtaining a total 4 arcsec X 8 arcsec
field which encompasses most of its ISM. Emission-line maps and broad-band
images obtained in this study indicate that HS 2236+1344 hosts three Giant HII
regions. Our data also reveal some faint curved features in the BCD periphery
that might be due to tidal perturbations or expanding ionized-gas shells. The
ISM velocity field shows systematic gradients along the major axis of the BCD,
with its south-eastern and north-western half differing by ~80 km/s in their
recessional velocity. The Ha and Hb equivalent width distribution in the
central part of HS 2236+1344 is consistent with a very young (~3 Myr) burst.
Our surface photometry analysis indicates that the ongoing starburst provides
~50% of the total optical emission, similar to other BCDs. It also reveals an
underlying lower-surface brightness component with moderately red colors, which
suggest that the galaxy has undergone previous star formation. We derive an
integrated oxygen abundance of 12+log(O/H)=7.53\pm0.06 and a nitrogen-to-oxygen
ratio of log(N/O)=-1.57\pm0.19. Our results are consistent, within the
uncertainties, with a homogeneous distribution of oxygen and nitrogen within
the ISM of the galaxy. (abridged)Comment: 15 pages, 16 figures, accepted for publication in A&
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