Surface Electromagnetic Waves Thermally Excited: Radiative Heat Transfer, Coherence Properties and Casimir Forces Revisited in the Near Field

We review in this article the influence of surface waves on the thermally excited electromagnetic field. We study in particular the field emitted at subwalength distances of material surfaces. After reviewing the main properties of surface waves, we introduce the fluctuation-dissipation theorem that allows to model the fluctuating electromagnetic fields. We then analyse the contribution of these waves in a variety of phenomena. They give a leading contribution to the density of electromagnetic states, they produce both temporal coherence and spatial coherence in the near field of planar thermal sources. They can be used to modify radiative properties of surfaces and to design partially spatially coherent sources. Finally, we discuss the role of surface waves in the radiative heat transfer and the theory of dispersion forces at the subwavelength scale.Comment: Redig\'{e} \`{a} la fin de l'ann\'{e}e 2004. Accept\'{e} dans Surface Science Report

A unified probabilistic model of the perception of three-dimensionnal structure from optic flow

voir basilic : http://emotion.inrialpes.fr/bibemotion/2006/CDWB06/ note: Submitted to Biological cyberneticsHuman observers can perceive the threedimensional (3-D) structure of their environment using various cues, an important one of which is motion parallax. The motion of any points projection on the retina depends both on the points movement in space and on its distance from the eye. Therefore, retinal motion can be used to extract the 3-D structure of the environment and the shape of objects, in a pHuman observers can perceive the threedimensional (3-D) structure of their environment using various cues, an important one of which is motion parallax. The motion of any points projection on the retina depends both on the points movement in space and on its distance from the eye. Therefore, retinal motion can be used to extract the 3-D structure of the environment and the shape of objects, in a process known as structurefrom- motion (sfm). However, because many combinations of 3-D structure and motion can lead to the same optic flow, sfm is an ill-posed inverse problem. The rigidity assumption is a constraint supposed to formally solve the sfm problem and to account for human performance. Recently, however, a number of psychophysical results, in both moving and stationary human observers, have shown that the rigidity assumption alone cannot account for sfm, but no model is known to account for the new results. Here, we construct a Bayesian model of sfm based on only one new assumption, that of stationarity, coupled with the assumption of rigidity. The predictions of the model, calculated using a new and powerful methodology called Bayesian programming, account for a wide variety of experimental findings

Search for CP Violation in the Decay Z -> b (b bar) g

About three million hadronic decays of the Z collected by ALEPH in the years 1991-1994 are used to search for anomalous CP violation beyond the Standard Model in the decay Z -> b \bar{b} g. The study is performed by analyzing angular correlations between the two quarks and the gluon in three-jet events and by measuring the differential two-jet rate. No signal of CP violation is found. For the combinations of anomalous CP violating couplings, ${\hat{h}}_b = {\hat{h}}_{Ab}g_{Vb}-{\hat{h}}_{Vb}g_{Ab}$ and $h^{\ast}_b = \sqrt{\hat{h}_{Vb}^{2}+\hat{h}_{Ab}^{2}}$, limits of \hat{h}_b < 0.59$and$h^{\ast}_{b} < 3.02$ are given at 95\% CL.Comment: 8 pages, 1 postscript figure, uses here.sty, epsfig.st

Performance of an endcap prototype of the ATLAS accordion electromagnetic calorimeter

The design and construction of a lead-liquid argon endcap calorimeter prototype using an accordion geometry and conceived as a sector of the inner wheel of the endcap calorimeter of the future ATLAS experiment at the LHC is described. The performance obtained using electron beam data is presented. The main results are an energy resolution with a sampling term below $11\%/\sqrt{E(\rm GeV)}$ and a small local constant term, a good linearity of the response with the incident energy and a global constant term of 0.8\% over an extended area in the rapidity range of $2.2 < \eta <2.9$. These properties make the design suitable for the ATLAS electromagnetic endcap calorimeter

Performance of a large scale prototype of the ATLAS accordion electromagnetic calorimeter

A 2 m long prototype of a lead-liquid argon electromagnetic calorimeter with accordion-shaped electrodes, conceived as a sector of the barrel calorimeter of the future ATLAS experiment at the LHC, has been tested with electron and pion beams in the energy range 10 to 287 GeV. A sampling term of 10%/root E(GeV) was obtained for electrons in the rapidity range 0 < eta < 1, while the constant term measured over an area of about 1 m(2) is 0.69%. With a cell size of 2.7 cm the position resolution is. about 4 mm/root E(GeV)

The Size, Shape, Albedo, Density, and Atmospheric Limit of Transneptunian Object (50000) Quaoar from Multi-chord Stellar Occultations

We present results derived from the first multi-chord stellar occultations by the transneptunian object (50000) Quaoar, observed on 2011 May 4 and 2012 February 17, and from a single-chord occultation observed on 2012 October 15. If the timing of the five chords obtained in 2011 were correct, then Quaoar would possess topographic features (crater or mountain) that would be too large for a body of this mass. An alternative model consists in applying time shifts to some chords to account for possible timing errors. Satisfactory elliptical fits to the chords are then possible, yielding an equivalent radius R [SUB]equiv[/SUB] = 555 ± 2.5 km and geometric visual albedo p[SUB]V[/SUB] = 0.109 ± 0.007. Assuming that Quaoar is a Maclaurin spheroid with an indeterminate polar aspect angle, we derive a true oblateness of \epsilon = 0.087^{+0.0268}_{-0.0175}, an equatorial radius of 569^{+24}_{-17} km, and a density of 1.99 ± 0.46 g cm[SUP]–3[/SUP]. The orientation of our preferred solution in the plane of the sky implies that Quaoar's satellite Weywot cannot have an equatorial orbit. Finally, we detect no global atmosphere around Quaoar, considering a pressure upper limit of about 20 nbar for a pure methane atmosphere.Peer reviewe