3,618 research outputs found
Integrated Eagle/BDS-D Research Resolution Of Behavior Representation Methods Of CCTT SAF And ModSAF Interim Report: Behavior Representation Integration Techniques
Report on the first engineering change proposal, including track Eagle units within computer generated forces testbed, base Eagle unit detection on line of sight, platoon and batallion disaggregation, and manned simulators
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The quality of political information
The article conceptualizes the quality of political information and shows how the concept can be used for empirical research. I distinguish three aspects of quality (intelligibility, relevance, validity) and use them to judge the constituent foundations of political information, that is component claims (statements of alleged facts) and connection claims (argumentative statements created by causally linking two component claims). The resulting conceptual map thus entails six manifestations of information quality (component claimintelligibility, connection claim intelligibility, component claimrelevance, connection claim relevance, component claim validity, and connection claim validity). I explain how the conceptual map can be used to make sense of the eclectic variety of existing research, and how it can advance new empirical research, as a guide for determining variation in information quality, as a conceptual template for the analysis of different types of political messages and their common quality deficiencies, and as a generator of new research questions and theoretical expectations
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The integrated database for African policymakers
The Integrated Database for African Policymakers (IDAPs; http://www.walker.ac.uk/projects/idaps-integrated-database-for-african-policy-makers/), is a technological initiative to intended to provide valuable insight and quantitative evidence to policy makers, planners and doers, at international, national and local levels to inform scenario planning and support investment interventions for early action and adaptation. It also provides a rich source of data for researchers exploring the impacts of climate change in rural African communities, and potentially beyond. IDAPS is jointly led by the Walker Institute and Evidence for Development, our embedded NGO partner
Age and sex-selective predation moderate the overall impact of predators
Ā© 2014 The Authors. Journal of Animal Ecology published by John Wiley & Sons Ltd on behalf of British Ecological Society. Acknowledgements: Thanks to J. Reid, S. Redpath, A. Beckerman and an anonymous reviewer for their helpful comments on a previous version of the manuscript. This work was partly funded by a Natural Environment Research Council studentship NE/J500148/1 to SH and a grant NE/F021402/1 to XL and by Natural Research Limited. Forest Research funded all the fieldwork on goshawks, tawny owls and field voles during 1973ā1996. We thank B. Little, P. Hotchin, D. Anderson and all field assistants for their help with data collection and Forest Enterprise, T. Dearnley and N. Geddes for allowing and facilitating work in Kielder Forest. In addition, we are grateful to English Nature and the BTO for kindly issuing licences annually visit goshawk nest sites. Data accessibility: All data associated with the study which have not already been given in the text are available from the Dryad Digital Repository: http://doi.org/10.5061/dryad.h1289 (Hoy et al. 2014).Peer reviewedPublisher PD
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Sea ice and the ocean mixed layer over the Antarctic shelf seas
An ocean mixed-layer model has been incorporated into the Los Alamos sea ice
model CICE to investigate regional variations in the surface-driven formation
of Antarctic shelf waters. This model captures well the expected sea ice
thickness distribution, and produces deep (> 500 m) mixed layers in the
Weddell and Ross shelf seas each winter. This results in the complete
destratification of the water column in deep southern coastal regions leading
to high-salinity shelf water (HSSW) formation, and also in some shallower
regions (no HSSW formation) of these seas. Shallower mixed layers are
produced in the Amundsen and Bellingshausen seas. By deconstructing the
surface processes driving the mixed-layer depth evolution, we show that the
net salt flux from sea ice growth/melt dominates the evolution of the mixed
layer in all regions, with a smaller contribution from the surface heat flux
and a negligible input from wind stress. The Weddell and Ross shelf seas
receive an annual surplus of mixing energy at the surface; the Amundsen shelf
sea energy input in autumn/winter is balanced by energy extraction in
spring/summer; and the Bellingshausen shelf sea experiences an annual surface
energy deficit, through both a low energy input in autumn/winter and the
highest energy loss in spring/summer. An analysis of the sea ice mass balance
demonstrates the contrasting mean ice growth, melt and export in each region.
The Weddell and Ross shelf seas have the highest annual ice growth, with a
large fraction exported northwards each year, whereas the Bellingshausen
shelf sea experiences the highest annual ice melt, driven by the advection of
ice from the northeast. A linear regression analysis is performed to
determine the link between the autumn/winter mixed-layer deepening and
several atmospheric variables. The Weddell and Ross shelf seas show stronger
spatial correlations (temporal mean ā intra-regional variability) between the
autumn/winter mixed-layer deepening and several atmospheric variables
compared to the Amundsen and Bellingshausen. In contrast, the Amundsen and
Bellingshausen shelf seas show stronger temporal correlations (shelf sea mean
ā interannual variability) between the autumn/winter mixed-layer deepening
and several atmospheric variables
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Sea iceāocean feedbacks in the Antarctic shelf seas
Observed changes in Antarctic sea ice are poorly understood, in part due to the complexity of its interactions with the atmosphere and ocean. A highly simplified, coupled sea iceāocean mixed layer model has been developed to investigate the importance of sea iceāocean feedbacks on the evolution of sea ice and the ocean mixed layer in two contrasting regions of the Antarctic continental shelf ocean: the Amundsen Sea, which has warm shelf waters, and the Weddell Sea, which has cold and saline shelf waters. Modeling studies where we deny the feedback response to surface air temperature perturbations show the importance of feedbacks on the mixed layer and ice cover in the Weddell Sea to be smaller than the sensitivity to surface atmospheric conditions. In the Amundsen Sea the effect of surface air temperature perturbations on the sea ice are opposed by changes in the entrainment of warm deep waters into the mixed layer. The net impact depends on the relative balance between changes in sea ice growth driven by surface perturbations and basal-driven melting. The changes in the entrainment of warm water in the Amundsen Sea were found to have a much larger impact on the ice volume than perturbations in the surface energy budget. This creates a net negative ice albedo feedback in the Amundsen Sea, reversing the sign of this typically positive feedback mechanism
Characterization of ellipses as uniformly dense sets with respect to a family of convex bodies
Let K \subset R^N be a convex body containing the origin. A measurable set G
\subset R^N with positive Lebesgue measure is said to be uniformly K-dense if,
for any fixed r > 0, the measure of G \cap (x + rK) is constant when x varies
on the boundary of G (here, x + rK denotes a translation of a dilation of K).
We first prove that G must always be strictly convex and at least C1,1-regular;
also, if K is centrally symmetric, K must be strictly convex, C1,1-regular and
such that K = G - G up to homotheties; this implies in turn that G must be
C2,1- regular. Then for N = 2, we prove that G is uniformly K-dense if and only
if K and G are homothetic to the same ellipse. This result was already proven
by Amar, Berrone and Gianni in [3]. However, our proof removes their regularity
assumptions on K and G and, more importantly, it is susceptible to be
generalized to higher dimension since, by the use of Minkowski's inequality and
an affine inequality, avoids the delicate computations of the higher-order
terms in the Taylor expansion near r = 0 for the measure of G\cap(x+rK) (needed
in [3])
Optical Spectroscopic Survey of High-latitude WISE-selected Sources
We report on the results of an optical spectroscopic survey at high Galactic latitude (|b| ā„ 30Ā°) of a sample of WISE-selected targets, grouped by WISE W1 (Ī»_eff = 3.4 Ī¼m) flux, which we use to characterize the sources WISE detected. We observed 762 targets in 10 disjoint fields centered on ultraluminous infrared galaxy candidates using DEIMOS on Keck II. We find 0.30 Ā± 0.02 galaxies arcminā2 with a median redshift of z = 0.33 Ā± 0.01 for the sample with W1 ā„ 120 Ī¼Jy. The foreground stellar densities in our survey range from 0.23 Ā± 0.07 arcminā2 to 1.1 Ā± 0.1 arcminā2 for the same sample. We obtained spectra that produced science grade redshifts for ā„90% of our targets for sources with W1 flux ā„120 Ī¼Jy that also had an i-band flux gsim 18 Ī¼Jy. We used this for targeting very preliminary data reductions available to the team in 2010 August. Our results therefore present a conservative estimate of what is possible to achieve using WISE's Preliminary Data Release for the study of field galaxies
Surface Geometry of C60 on Ag(111)
The geometry of adsorbed C60 influences its collective properties. We report the first dynamical low-energy electron diffraction study to determine the geometry of a C60 monolayer, Ag(111)-(23Ć23)30Ā°-C60, and related density functional theory calculations. The stable monolayer has C60 molecules in vacancies that result from the displacement of surface atoms. C60 bonds with hexagons down, with their mirror planes parallel to that of the substrate. The results indicate that vacancy structures are the rule rather than the exception for C60 monolayers on close-packed metal surfaces. Ā© 2009 The American Physical Society
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