46,827 research outputs found
A universal solution
The phenomenon of an implicit function which solves a large set of second
order partial differential equations obtainable from a variational principle is
explicated by the introduction of a class of universal solutions to the
equations derivable from an arbitrary Lagrangian which is homogeneous of weight
one in the field derivatives. This result is extended to many fields. The
imposition of Lorentz invariance makes such Lagrangians unique, and equivalent
to the Companion Lagrangians introduced in [baker].Comment: arxiv version is already officia
MINERAL DYNAMICS OF THE SUBMERSED MACROPHYTE, MYRIOPHYLLUM HETEROPHYLLUM, AND THE COMPETITIVE ·INTERACTIONS FOR NUTRIENTS BETWEEN M. HETEROPHYLLUM, PHYTOPLANKTON AND THE SEDIMENTS IN LITTORAL WATERS
Graphics and composite material computer program enhancements for SPAR
User documentation is provided for additional computer programs developed for use in conjunction with SPAR. These programs plot digital data, simplify input for composite material section properties, and compute lamina stresses and strains. Sample problems are presented including execution procedures, program input, and graphical output
Exciton-polaron complexes in pulsed electrically-detected magnetic resonance
Several microscopic pathways have been proposed to explain the large magnetic
effects observed in organic semiconductors, but identifying and characterising
which microscopic process actually influences the overall magnetic field
response is challenging. Pulsed electrically-detected magnetic resonance
provides an ideal platform for this task as it intrinsically monitors the
charge carriers of interest and provides dynamical information which is
inaccessible through conventional magnetoconductance measurements. Here we
develop a general time domain theory to describe the spin-dependent reaction of
exciton-charge complexes following the coherent manipulation of paramagnetic
centers through electron spin resonance. A general Hamiltonian is treated, and
it is shown that the transition frequencies and resonance positions of the
exciton-polaron complex can be used to estimate inter-species coupling. This
work also provides a general formalism for analysing multi-pulse experiments
which can be used to extract relaxation and transport rates
Ignition of binary alloys of uranium
Experiments determine the effect of alloying additives on the ignition of uranium. Data on oxidation rates, ignition temperatures, and burning curves are provided in the report
Candidate High Redshift and Primeval Galaxies in Hubble Deep Field South
We present the results of colour selection of candidate high redshift
galaxies in Hubble Deep Field South (HDF-S) using the Lyman dropout scheme. The
HDF-S data we discuss were taken in a number of different filters extending
from the near--UV (F300W) to the infrared (F222M) in two different fields. This
allows us to select candidates with redshifts from z~3 to z~12. We find 15
candidate z~3 objects (F300W dropouts), 1 candidate z~4 object (F450W dropout)
and 16 candidate z5 objects (F606W dropouts) in the ~ 4.7 arcmin^2 WFPC-2
field, 4 candidate z~6 (optical dropouts) and 1 candidate z~8 (F110W dropout)
in the 0.84 arcmin^2 NICMOS-3 field. No F160W dropouts are found (z~12). We
compare our selection technique with existing data for HDF-North and discuss
alternative interpretations of the objects. We conclude that there are a number
of lower redshift interlopers in the selections, including one previously
identified object (Treu et al. 1998), and reject those objects most likely to
be foreground contaminants. Even after this we conclude that the F606W dropout
list is likely to still contain substantial foreground contamination. The lack
of candidate very high redshift UV-luminous galaxies supports earlier
conclusions by Lanzetta et al. (1998). We discuss the morphologies and
luminosity functions of the high redshift objects, and their cosmological
implications.Comment: Accepted for publication in MNRA
Alternatives for Measuring Hazardous Waste Reduction
PTI Project number 233U-4913FRHWRIC Project Number 89006
FIP Bias Evolution in a Decaying Active Region
Solar coronal plasma composition is typically characterized by first
ionization potential (FIP) bias. Using spectra obtained by Hinode's EUV Imaging
Spectrometer (EIS) instrument, we present a series of large-scale, spatially
resolved composition maps of active region (AR) 11389. The composition maps
show how FIP bias evolves within the decaying AR from 2012 January 4-6.
Globally, FIP bias decreases throughout the AR. We analyzed areas of
significant plasma composition changes within the decaying AR and found that
small-scale evolution in the photospheric magnetic field is closely linked to
the FIP bias evolution observed in the corona. During the AR's decay phase,
small bipoles emerging within supergranular cells reconnect with the
pre-existing AR field, creating a pathway along which photospheric and coronal
plasmas can mix. The mixing time scales are shorter than those of plasma
enrichment processes. Eruptive activity also results in shifting the FIP bias
closer to photospheric in the affected areas. Finally, the FIP bias still
remains dominantly coronal only in a part of the AR's high-flux density core.
We conclude that in the decay phase of an AR's lifetime, the FIP bias is
becoming increasingly modulated by episodes of small-scale flux emergence, i.e.
decreasing the AR's overall FIP bias. Our results show that magnetic field
evolution plays an important role in compositional changes during AR
development, revealing a more complex relationship than expected from previous
well-known Skylab results showing that FIP bias increases almost linearly with
age in young ARs (Widing Feldman, 2001, ApJ, 555, 426)
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