Limit theorems for some adaptive MCMC algorithms with subgeometric kernels: Part II

We prove a central limit theorem for a general class of adaptive Markov Chain Monte Carlo algorithms driven by sub-geometrically ergodic Markov kernels. We discuss in detail the special case of stochastic approximation. We use the result to analyze the asymptotic behavior of an adaptive version of the Metropolis Adjusted Langevin algorithm with a heavy tailed target density.Comment: 34 page

Accuracy of Tilt Rotor Hover Performance Predictions

The accuracy of various methods used to predict tilt rotor hover performance was established by comparing predictions with large-scale experimental data. A wide range of analytical approaches were examined. Blade lift was predicted with a lifting line analysis, two lifting surface analyses, and by a finite-difference solution of the full potential equation. Blade profile drag was predicted with two different types of airfoil tables and an integral boundary layer analysis. The inflow at the rotor was predicted using momentum theory, two types of prescribed wakes, and two free wake analyses. All of the analyses were accurate at moderate thrust coefficients. The accuracy of the analyses at high thrust coefficients was dependent upon their treatment of high sectional angles of attack on the inboard sections of the rotor blade. The analyses which allowed sectional lift coefficients on the inboard stations of the blade to exceed the maximum observed in two-dimensional wind tunnel tests provided better accuracy at high thrust coefficients than those which limited lift to the maximum two-dimensional value. These results provide tilt rotor aircraft designers guidance on which analytical approaches provide the best results, and the level of accuracy which can be expected from the best analyses

Collective excitations of a trapped Bose-Einstein condensate in the presence of a 1D optical lattice

We study low-lying collective modes of a horizontally elongated 87Rb condensate produced in a 3D magnetic harmonic trap with the addition of a 1D periodic potential which is provided by a laser standing-wave along the horizontal axis. While the transverse breathing mode results unperturbed, quadrupole and dipole oscillations along the optical lattice are strongly modified. Precise measurements of the collective mode frequencies at different height of the optical barriers provide a stringent test of the theoretical model recently introduced [M.Kraemer et al. Phys. Rev. Lett. 88 180404 (2002)].Comment: 4 pages, 4 figure

Damping and frequency shift in the oscillations of two colliding Bose-Einstein condensates

We have investigated the center-of-mass oscillations of a Rb87 Bose-Einstein condensate in an elongated magneto-static trap. We start from a trapped condensate and we transfer part of the atoms to another trapped level, by applying a radio-frequency pulse. The new condensate is produced far from its equilibrium position in the magnetic potential, and periodically collides with the parent condensate. We discuss how both the damping and the frequency shift of the oscillations are affected by the mutual interaction between the two condensates, in a wide range of trapping frequencies. The experimental data are compared with the prediction of a mean-field model.Comment: 5 RevTex pages, 7 eps figure

Automatic detection of arcs and arclets formed by gravitational lensing

We present an algorithm developed particularly to detect gravitationally lensed arcs in clusters of galaxies. This algorithm is suited for automated surveys as well as individual arc detections. New methods are used for image smoothing and source detection. The smoothing is performed by so-called anisotropic diffusion, which maintains the shape of the arcs and does not disperse them. The algorithm is much more efficient in detecting arcs than other source finding algorithms and the detection by eye.Comment: A&A in press, 12 pages, 16 figure

MOND and Cosmology

I review various ideas on MOND cosmology and structure formation beginning with non-relativistic models in analogy with Newtonian cosmology. I discuss relativistic MOND cosmology in the context of Bekenstein's theory and propose an alternative biscalar effective theory of MOND in which the acceleration parameter is identified with the cosmic time derivative of a matter coupling scalar field. Cosmic CDM appears in this theory as scalar field oscillations of the auxiliary "coupling strength" field.Comment: 8 pages, LaTeX, 2 figures, to appear in proceedings of IAP05 in Paris: Mass Profiles and Shapes of Cosmological Structures, G. Mamon, F. Combes, C. Deffayet and B. Fort (eds), (EDP-Sciences 2005