31,720 research outputs found
Lythraceae.
MARHOLD, K.; FELINER, G. N. (Ed.). IOPB Column
Temporal trend in the transfer of Sellafield-derived 14C into different size fractions of the carbonate component of NE Irish Sea sediment
From 1994 onwards, 14C discharges from the Sellafield nuclear fuel reprocessing plant have been made largely to the Northeast Irish Sea. They represent the largest contributor to UK and European populations of the collective dose commitment derived from the entire nuclear industry discharges. Consequently, it is important to understand the long-term fate of 14C in the marine environment. Research undertaken in 2000 suggested that the carbonate component of Northeast Irish Sea sediments would increase in 14C activity as mollusc shells, which have become enriched in Sellafield-derived 14C, are broken down by physical processes including wave action and incorporated into intertidal and sub-tidal sediments. The current study, undertaken in 2011, tested this hypothesis. The results demonstrate significant increases in 14C enrichments found in whole mussel shells compared to those measured in 2000. Additionally, in 2000, there was an enrichment above ambient background within only the largest size fraction (>500 μm) of the intertidal inorganic sediment at Nethertown and Flimby (north of Sellafield). In comparison, the present study has demonstrated 14C enrichments above ambient background in most size fractions at sites up to 40 km north of Sellafield, confirming the hypothesis set out more than a decade ago
Performance, Politics and Media: How the 2010 British General Election leadership debates generated ‘talk’ amongst the electorate.
During the British General Election 2010 a major innovation was introduced in part to improve engagement: a series of three live televised leadership debates took place where the leader of each of the three main parties, Labour, Liberal Democrat and Conservative, answered questions posed by members of the public and subsequently debated issues pertinent to the questions. In this study we consider these potentially ground breaking debates as the kind of event that was likely to generate discussion. We investigate various aspects of the ‘talk’ that emerged as a result of watching the debates. As an exploratory study concerned with situated accounts of the participants experiences we take an interpretive perspective. In this paper we outline the meta-narratives (of talk) associated with the viewing of the leadership debates that were identified, concluding our analysis by suggesting that putting a live debate on television and promoting and positioning it as a major innovation is likely to mean that is how the audience will make sense of it – as a media event
Science Basis for Changing Forest Structure to Modify Wildfire Behavior and Severity
This report describes the kinds, quality, amount, and gaps of scientific knowledge for making informed decisions on fuel treatments used to modify wildfire behavior and effects in dry forests of the interior Western United States (especially forests dominated by ponderosa pine and Douglas-fir). A review of scientific principles and applications relevant to fuel treatment primarily for the dry forests is provided for the following topics: fuels, fire hazard, fire behavior, fire effects, forest structure, treatment effects and longevity, landscape fuel patterns, and scientific tools useful for management and planning
Damage Spreading During Domain Growth
We study damage spreading in models of two-dimensional systems undergoing
first order phase transitions. We consider several models from the same
non-conserved order parameter universality class, and find unexpected
differences between them. An exact solution of the Ohta-Jasnow-Kawasaki model
yields the damage growth law , where in
dimensions. In contrast, time-dependent Ginzburg-Landau simulations and Ising
simulations in using heat-bath dynamics show power-law growth, but with
an exponent of approximately , independent of the system sizes studied.
In marked contrast, Metropolis dynamics shows damage growing via , although the damage difference grows as . PACS: 64.60.-i, 05.50.+qComment: 4 pags of revtex3 + 3 postscript files appended as a compressed and
uuencoded file. UIB940320
Modeling Porous Dust Grains with Ballistic Aggregates. II. Light Scattering Properties
We study the light scattering properties of random ballistic aggregates
constructed in Shen et al. (Paper I). Using the discrete-dipole-approximation,
we compute the scattering phase function and linear polarization for random
aggregates with various sizes and porosities, and with two different
compositions: 100% silicate and 50% silicate-50% graphite. We investigate the
dependence of light scattering properties on wavelength, cluster size and
porosity using these aggregate models. We find that while the shape of the
phase function depends mainly on the size parameter of the aggregates, the
linear polarization depends on both the size parameter and the porosity of the
aggregates, with increasing degree of polarization as the porosity increases.
Contrary to previous studies, we argue that monomer size has negligible effects
on the light scattering properties of ballistic aggregates, as long as the
constituent monomer is smaller than the incident wavelength up to
2*pi*a_0/lambda\sim 1.6 where a_0 is the monomer radius. Previous claims for
such monomer size effects are in fact the combined effects of size parameter
and porosity. Finally, we present aggregate models that can reproduce the phase
function and polarization of scattered light from the AU Mic debris disk and
from cometary dust, including the negative polarization observed for comets at
scattering angles 160<theta<180 deg. These aggregates have moderate porosities,
P\sim 0.6, and are of sub-micron-size for the debris disk case, or micron-size
for the comet case.Comment: Submitted to ApJ. Scattering properties can be downloaded at
http://www.astro.princeton.edu/~draine/SDJ2009.html Target geometries are at
http://www.astro.princeton.edu/~draine/agglom.htm
Quantum states on supersymmetric minisuperspace with a cosmological constant
Spatially homogeneous models in quantum supergravity with a nonvanishing
cosmological constant are studied. A class of exact nontrivial solutions of the
supersymmetry and Lorentz constraints is obtained in terms of the Chern-Simons
action on the spatially homogeneous 3-manifold, both in Ashketar variables
where the solution is explicit up to reality conditions, and, more concretely,
in the tetrad-representation, where the solutions are given as integral
representations differing only by the contours of integration. In the limit of
a vanishing cosmological constant earlier exact solutions for Bianchi type IX
models in the tetrad-representation are recovered and additional asymmetric
solutions are found.Comment: 14 pages, late
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