Weak gravitational lensing by an intervening large-scale structure induces a distinct signature in the cosmic microwave background ~CMB! that can be used to reconstruct the weak-lensing displacement map. Estimators for individual Fourier modes of this map can be combined to produce an estimator for the lensing-potential power spectrum. The naive estimator for this quantity will be biased upward...

The dynamics of a network of N nonlinear elements interacting via random asymmetric weights is studied analytically. A transition from an ordered phase to a chaotic one is obtained when the number of relevant modes used to construct the weights exceeds N 1y2 # d # 1. In the ordered phase the dynamics of each element is characterized by an embedding dimension equal to one, or is dominated by one...

This letter describes the use of THz time-domain spectroscopy (TDS) applied in transmission to the secondary explosive 1,3,5 trinitro-s-triazine. Samples were also subjected to Fourier transform infrared spectroscopy over the same range for comparison. A detailed spectroscopy study is presented. General agreement between results from both methods confirms the absorption features found. A compar...

The traditional view on extra-dimensions is the Kaluza-Klein picture: the matter fields live in compact (usually flat) extra-dimensions, and their Fourier expansion along the extra-coordinates lead to an infinite collection of so-called Kaluza-Klein modes, which can be interpreted as four-dimensional fields. Their mass spectrum is very specific since it is discrete with a mass gap of the order ...

We have investigated the terahertz (THz) spectrum of 2,4-DNT by using Fourier transform infrared spectroscopy in the 0.2–19.5 THz region. We also examined low-frequency intermolecular or phonon modes between 0.2 and 1.8 THz via THz time-domain spectroscopy. The extracted absorption coefficient and refractive index of an intermolecular band at 1.08 THz are 110 cm 1 and 1.67, respectively. Densit...

It is shown that the use of a high power alpha of the Laplacian in the dissipative term of hydrodynamical equations leads asymptotically to truncated inviscid conservative dynamics with a finite range of spatial Fourier modes. Those at large wave numbers thermalize, whereas modes at small wave numbers obey ordinary viscous dynamics [C. Cichowlas et al., Phys. Rev. Lett. 95, 264502 (2005)10.1103...

In this paper, we investigate the stability for a finite harmonic lattice under a certain class of boundary conditions. A rigorous eigenvalue study clarifies that the invalidity of Fourier modes as the basis results in the deficiency of standard reflection coefficient approach for stability analysis. In a certain parameter range, unstable surface modes exist in the form of exponential decay in ...

This is the first part of a threefold article, aimed at solving numerically the Poisson problem in three-dimensional prismatic or axisymmetric domains. In this first part, the Fourier Singular Complement Method is introduced and analysed, in prismatic domains. In the second part, the FSCM is studied in axisymmetric domains with conical vertices, whereas, in the third part, implementation issues...

Analysis of tides and internal waves from model studies in the South China Sea is done using three techniques. We summarize results from standard Fourier methods, continuous wavelet analysis and the direct scattering transform. Because the Fourier and wavelet analysis are inherently linear methods their utility in application to nonlinear dynamics is often questioned. Nevertheless, they have sh...

In this article, we analyse bifurcations from stationary stable spots to travelling spots in a planar three-component FitzHugh–Nagumo system that was proposed previously as a phenomenological model of gas-discharge systems. By combining formal analyses, center-manifold reductions, and detailed numerical continuation studies, we show that, in the parameter regime under consideration, the station...