980 research outputs found
DART: A 3D Model for Remote Sensing Images and Radiative Budget of Earth Surfaces
Modeling the radiative behavior and the energy budget of land surfaces is relevant for many scientific domains such as the study of vegetation functioning with remotely acquired information. DART model (Discrete Anisotropic Radiative Transfer) is developed since 1992. It is one of the most complete 3D models in this domain. It simulates radiative transfer (R.T.) in the optical domain: 3D radiative budget and remote sensing images (i.e., radiance, reflectance, brightness temperature) of vegetation and urban Earth surfaces, for any atmosphere, wavelength, sun/view direction, altitude and spatial resolution. It uses an innovative multispectral approach (flux tracing, exact kernel, discrete ordinate techniques) over the whole optical domain. Here, its potential is illustrated with the case of urban and tropical forest canopies. Moreover, three recent improvements in terms of functionality and operability are presented: account of Earth/Atmosphere curvature for oblique remote sensing measurements, importation of 3D objects simulated as the juxtaposition of triangles with the possibility to transform them into 3D turbid objects, and R.T. simulation in landscapes that have a continuous topography and landscapes that are non repetitive. Finally, preliminary results concerning two application domains are presented. 1) 2D distribution of the reflectance, brightness temperature and radiance measured by a geostationary satellite over a whole continent. 2) 3D radiative budget of natural and urban surfaces with a DART energy budget (EB) component that is being developed. This new model, called DARTEB, is intended to simulate the energy budget of land surfaces
Quine, Ontology, and Physicalism
Quine's views on ontology and naturalism are well-known but rarely considered in tandem. According to my interpretation the connection between them is vital. I read Quine as a global epistemic structuralist. Quine thought we only ever know objects qua solutions to puzzles about significant intersections in observations. Objects are always accessed descriptively, via their roles in our best theory. Quine's Kant lectures contain an early version of epistemic structuralism with uncharacteristic remarks about the mental. Here Quine embraces mitigated anomalous monism, allowing introspection and the availability in principle of full physical descriptions of the perceptual states which get science off the ground. Later versions abandon these ideas. My epistemic-structural interpretation explains why. I argue first-personal introspective access to mental states is incompatible with global epistemic structuralism
Effects of N,N-diethyl-m-toluamide (DEET) in the cellular processes leading to angiogenesis
National audienc
Elliptic Flow Analysis at RHIC with the Lee-Yang Zeroes Method in a Relativistic Transport Approach
The Lee-Yang zeroes method is applied to study elliptic flow () in Au+Au
collisions at ~GeV, with the UrQMD model. In this transport
approach, the true event plane is known and both the nonflow effects and
event-by-event fluctuations exist. Although the low resolutions prohibit
the application of the method for most central and peripheral collisions, the
integral and differential elliptic flow from the Lee-Yang zeroes method agrees
with the exact values very well for semi-central collisions.Comment: 4 pages, 4 figure
Inferring periodic orbits from spectra of simple shaped micro-lasers
Dielectric micro-cavities are widely used as laser resonators and
characterizations of their spectra are of interest for various applications. We
experimentally investigate micro-lasers of simple shapes (Fabry-Perot, square,
pentagon, and disk). Their lasing spectra consist mainly of almost equidistant
peaks and the distance between peaks reveals the length of a quantized periodic
orbit. To measure this length with a good precision, it is necessary to take
into account different sources of refractive index dispersion. Our experimental
and numerical results agree with the superscar model describing the formation
of long-lived states in polygonal cavities. The limitations of the
two-dimensional approximation are briefly discussed in connection with
micro-disks.Comment: 13 pages, 19 figures, accepted for publication in Physical Review
Strangeness Production at RHIC in the Perturbative Regim
We investigate strange quark production in Au-Au collisions at RHIC in the
framework of the Parton Cascade Model(PCM). The yields of (anti-) strange
quarks for three production scenarios -- primary-primary scattering, full
scattering, and full production -- are compared to a proton-proton baseline.
Enhancement of strange quark yields in central Au-Au collisions compared to
scaled p-p collisions increases with the number of secondary interactions. The
centrality dependence of strangeness production for the three production
scenarios is studied as well. For all production mechanisms, the strangeness
yield increases with . The perturbative QCD regime
described by the PCM is able to account for up to 50% of the observed
strangeness at RHIC.Comment: 10 pages, 4 figures, IOP forma
Remote Sensing Studies of Urban Canopies: 3D Radiative Transfer Modeling
Need for better understanding and more accurate estimation of radiative fluxes in urban environments, specifically urban surface albedo and exitance, motivates development of new remote sensing and three‐dimensional (3D) radiative transfer (RT) modeling methods. The discrete anisotropic radiative transfer (DART) model, one of the most comprehensive physically based 3D models simulating Earth/atmosphere radiation interactions, was used in combination with satellite data (e.g., Landsat‐8 observations) to better parameterize the radiative budget components of cities, such as Basel in Switzerland. After presenting DART and its recent RT modeling functions, we present a methodological concept for estimating urban fluxes using any satellite image data
14th International Workshop on Advanced Computing and Analysis Techniques in Physics Research (ACAT 2011): Preface
No abstract available
Nuclear suppression of heavy quark production at forward rapidities in relativistic heavy ion collisions
We calculate nuclear suppression of heavy quarks produced from the
initial fusion of partons in nucleus-nucleus collisions at RHIC and LHC
energies. We take the shadowing as well as the energy loss suffered by them
while passing through Quark Gluon Plasma into account. We obtain results for
charm and bottom quarks at several rapidities using different mechanisms for
energy loss, to see if we can distinguish between them.Comment: 21 pages including 13 figures. To appear in J. Phys.
- …