943 research outputs found
A new global fAPAR and LAI dataset derived from optimal albedo estimates: comparison with MODIS products
We present the first comparison between new fAPAR and LAI products derived from the GlobAlbedo dataset and the widely-used MODIS fAPAR and LAI and products. The GlobAlbedo derived products are produced using a 1D two-stream radiative transfer (RT) scheme designed explicitly for global parameter retrieval from albedo, with consistency between RT model assumptions and observations, as well as with typical large-scale land surface model RT schemes.
The approach does not require biome-specific structural assumptions (e.g. cover, clumping, understory), unlike more detailed 3D RT model approaches. GlobAlbedo-derived values of fAPAR and LAI are compared with MODIS values over 2002-2011 at multiple flux tower sites within selected biomes, over 1200 × 1200 km regions and globally. GlobAlbedo-derived fAPAR and LAI values are temporally more stable than the MODIS values due to (1) the smoothness of the underlying albedo, derived via optimal estimation (assimilation) using an a priori estimate of albedo derived from an albedo ‘climatology’ (composited multi-year albedo observations) and (2) space-time invariant prior information in the inversion of the two-stream RT scheme. Parameters agree closely in timing but with GlobAlbedo values consistently lower than MODIS, particularly for LAI. Larger differences occur in winter (when values are lower) and in the Southern hemisphere. Globally, we find that: GlobAlbedo-derived fAPAR is ~0.9- 1.01 × MODIS fAPAR with an offset of ~0.03; GlobAlbedo-derived LAI is ~0.6 × MODIS LAI with an offset of ~0.2. Differences arise due to the RT model assumptions underlying the products, meaning care is required in interpreting either set of values, particularly when comparing to finescale ground-based estimates. We present global calibrations between GlobAlbedo-derived and MODIS products.JRC.H.5-Land Resources Managemen
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The effects of emotional states and traits on risky decision-making.
Understanding the role of emotional states is critical for predicting the kind of decisions people will make in risky situations. Currently, there is little understanding as to how emotion influences decision-making in situations such as terrorist attacks, natural disasters, pandemics, and combat. To help address this, we used behavioral and neuroimaging methods to examine how emotion states and traits influence decisions. Specifically, this study used a wheel of fortune behavioral task and functional magnetic resonance imaging (fMRI) to examine the effects of emotional states and traits on decision-making pertaining to the degree of risk people are willing to make in specific situations. The behavioral results are reported here. The neural data requires additional time to analyze and will be reported at a future date. Biases caused by emotion states and traits were found regarding the likelihood of making risky decisions. The behavioral results will help provide a solid empirical foundation for modeling the effects of emotion on decision in risky situations
The nucleon's strange electromagnetic and scalar matrix elements
Quenched lattice QCD simulations and quenched chiral perturbation theory are
used together for this study of strangeness in the nucleon. Dependences of the
matrix elements on strange quark mass, valence quark mass and momentum transfer
are discussed in both the lattice and chiral frameworks. The combined results
of this study are in good agreement with existing experimental data and
predictions are made for upcoming experiments. Possible future refinements of
the theoretical method are suggested.Comment: 24 pages, 9 figure
Classically Perfect Gauge Actions on Anisotropic Lattices
We present a method for constructing classically perfect anisotropic actions
for SU(3) gauge theory based on an isotropic Fixed Point Action. The action is
parametrised using smeared (``fat'') links. The construction is done explicitly
for anisotropy and 4. The corresponding renormalised
anisotropies are determined using the torelon dispersion relation. The
renormalisation of the anisotropy is small and the parametrisation describes
the true action well. Quantities such as the static quark-antiquark potential,
the critical temperature of the deconfining phase transition and the low-lying
glueball spectrum are measured on lattices with anisotropy . The mass of
the scalar glueball is determined to be 1580(60) MeV, while the tensor
glueball is at 2430(60) MeV.Comment: 64 pages, 19 figures, LaTe
Foundations to the unified psycho-cognitive engine.
This document outlines the key features of the SNL psychological engine. The engine is designed to be a generic presentation of cognitive entities interacting among themselves and with the external world. The engine combines the most accepted theories of behavioral psychology with those of behavioral economics to produce a unified simulation of human response from stimuli through executed behavior. The engine explicitly recognizes emotive and reasoned contributions to behavior and simulates the dynamics associated with cue processing, learning, and choice selection. Most importantly, the model parameterization can come from available media or survey information, as well subject-matter-expert information. The framework design allows the use of uncertainty quantification and sensitivity analysis to manage confidence in using the analysis results for intervention decisions
The Star Formation History and Dust Content in the Far Outer Disc of M31
We present a detailed analysis of two fields located 26 kpc (~5 scalelengths)
from the centre of M31. One field samples the major axis populations--the Outer
Disc field--while the other is offset by ~18' and samples the Warp in the
stellar disc. The CMDs based on HST/ACS imaging reach old main-sequence
turn-offs (~12.5 Gyr). We apply the CMD-fitting technique to the Warp field to
reconstruct the star formation history (SFH). We find that after undergoing
roughly constant SF until about 4.5 Gyr ago, there was a rapid decline in
activity and then a ~1.5 Gyr lull, followed by a strong burst lasting 1.5 Gyr
and responsible for 25% of the total stellar mass in this field. This burst
appears to be accompanied by a decline in metallicity which could be a
signature of the inflow of metal-poor gas. The onset of the burst (~3 Gyr ago)
corresponds to the last close passage of M31 and M33 as predicted by detailed
N-body modelling, and may have been triggered by this event. We reprocess the
deep M33 outer disc field data of Barker et al. (2011) in order to compare
consistently-derived SFHs. This reveals a similar duration burst that is
exactly coeval with that seen in the M31 Warp field, lending further support to
the interaction hypothesis. The complex SFHs and the smoothly-varying
age-metallicity relations suggest that the stellar populations observed in the
far outer discs of both galaxies have largely formed in situ rather than
migrated from smaller galactocentric radii. The strong differential reddening
affecting the CMD of the Outer Disc field prevents derivation of the SFH.
Instead, we quantify this reddening and find that the fine-scale distribution
of dust precisely follows that of the HI gas. This indicates that the outer HI
disc of M31 contains a substantial amount of dust and therefore suggests
significant metal enrichment in these parts, consistent with inferences from
our CMD analysis.Comment: Abstract shortened. 17 pages, 12 figures (+ 6 pages & 5 figures in
Appendix). MNRAS, in pres
Life and the Technical Transformation of Différance: Stiegler and the Noopolitics of Becoming Non-Inhuman
Through a re-articulation of Derridean différance, Bernard Stiegler claims that the human is defined by an originary default that displaces all psychic and social life onto technical supplements. His philosophy of technics re-articulates the logic of the supplement as concerning both human reflexivity and its supports, and the history of the différance of life itself. This has been criticised for reducing Derrida’s work to a metaphysics of presence, and for instituting a humanism of the relation to the inorganic. By refuting these claims, this article will show that Stiegler’s doubling of différance enables him to articulate the human as constituted by both the individuation characteristic of ‘life’, and that of a technical, psychic and collective individuation. Putting forward a reading of the logic of the trace in life, and emphasising the aspects of Leroi-Gourhan, Simondon, and Canguilhem that Stiegler uses in his reading of Derrida, I will demonstrate that the political stakes of adaption and adoption in Noo-Politics require this re-articulation of différance. Technics shapes the human future, arising from this differential mutation; marking the invention of the human as the site of the political
Left ventricular systolic dysfunction, heart failure, and the risk of stroke and systemic embolism in patients with atrial fibrillation : insights from the ARISTOTLE trial
We examined the risk of stroke or systemic embolism (SSE) conferred by heart failure (HF) and left ventricular systolic dysfunction (LVSD) in the Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation Trial (ARISTOTLE), as well as the effect of apixaban versus warfarin
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Understanding communication in counterterrorism crisis management.
This report describes the purpose and results of the two-year, Sandia-sponsored Laboratory Directed Research and Development (LDRD) project entitled Understanding Communication in Counterterrorism Crisis Management The purpose of this project was to facilitate the capture of key communications among team members in simulated training exercises, and to learn how to improve communication in that domain. The first section of this document details the scenario development aspects of the simulation. The second section covers the new communication technologies that were developed and incorporated into the Weapons of Mass Destruction Decision Analysis Center (WMD-DAC) suite of decision support tools. The third section provides an overview of the features of the simulation and highlights its communication aspects. The fourth section describes the Team Communication Study processes and methodologies. The fifth section discusses future directions and areas in which to apply the new technologies and study results obtained as a result of this LDRD
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