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The interstellar medium seems to have an underlying fractal structure which can be characterized through its fractal dimension. However, interstellar clouds are observed as projected two-dimensional images, and the projection of a…

Astrophysics · Physics 2007-05-23 Nestor Sanchez , Emilio J. Alfaro , Enrique Perez

We present the first application of the Wavelet Scattering Transform (WST) in order to constrain the nature of gravity using the three-dimensional (3D) large-scale structure of the universe. Utilizing the Quijote-MG N-body simulations, we…

Cosmology and Nongalactic Astrophysics · Physics 2024-12-12 Georgios Valogiannis , Francisco Villaescusa-Navarro , Marco Baldi

The large side aperture of the NuSTAR telescope for unfocused photons (so-called stray light) is a known source of rich astrophysical information. To support many studies based on the NuSTAR stray light data, we present a fully automatic…

Instrumentation and Methods for Astrophysics · Physics 2023-10-30 Andrey Mukhin , Roman Krivonos , Alexey Vikhlinin , Brian Grefenstette , Kristin Madsen , Daniel Wik

The Easy Path Wavelet Transform is an adaptive transform for bivariate functions (in particular natural images) which has been proposed in [1]. It provides a sparse representation by finding a path in the domain of the function leveraging…

Information Theory · Computer Science 2017-02-16 Renato Budinich

W projection is a commonly-used approach to allow interferometric imaging to be accelerated by Fast Fourier Transforms (FFTs), but it can require a huge amount of storage for convolution kernels. The kernels are not separable, but we show…

Instrumentation and Methods for Astrophysics · Physics 2016-01-27 Bruce Merry

Continuous wavelet analysis has been increasingly employed in various fields of science and engineering due to its remarkable ability to maintain optimal resolution in both space and scale. Here, we introduce wavelet-based statistics,…

Cosmology and Nongalactic Astrophysics · Physics 2022-07-29 Yun Wang , Hua-Yu Yang , Ping He

Wavelets are widely used in various disciplines to analyse signals both in space and scale. Whilst many fields measure data on manifolds (i.e., the sphere), often data are only observed on a partial region of the manifold. Wavelets are a…

Information Theory · Computer Science 2023-04-24 Patrick J. Roddy

We present a method of measuring galaxy power spectrum based on the multiresolution analysis of the discrete wavelet transformation (DWT). Since the DWT representation has strong capability of suppressing the off-diagonal components of the…

Astrophysics · Physics 2009-10-31 Li-Zhi Fang , Long-Long Feng

The influence of large-scale density fluctuations on structure formation on small scales is described by the three-point correlation function (bispectrum) in the so-called "squeezed configurations," in which one wavenumber, say $k_3$, is…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-19 Chi-Ting Chiang , Christian Wagner , Fabian Schmidt , Eiichiro Komatsu

Wavelets are closely related to the Schr\"odinger's wave functions and the interpretation of Born. Similarly to the appearance of atomic orbital, it is proposed to combine anti-symmetric wavelets into orbital wavelets. The proposed approach…

Signal Processing · Electrical Eng. & Systems 2020-10-02 H. M. de Oliveira , V. V. Vermehren , R. J. Cintra

Motivated by the existence problem of Fourier frames on fractal measures, we introduce Bessel and frame measures for a given finite measure on $\br^d$, as extensions of the notions of Bessel and frame spectra that correspond to bases of…

Functional Analysis · Mathematics 2012-04-03 Dorin Ervin Dutkay , Deguang Han , Eric Weber

Weak lensing provides a direct measure of the distribution of mass in the universe, and is therefore a uniquely powerful probe of dark matter. Weak lensing can also be used to measure the twin phenomenon of dark energy, via its effect upon…

Astrophysics · Physics 2007-05-23 Richard Massey , Alexandre Refregier , Jason Rhodes

We present a new method for the analysis of images, a fundamental task in observational astronomy. It is based on the linear decomposition of each object in the image into a series of localised basis functions of different shapes, which we…

Astrophysics · Physics 2008-11-26 Alexandre Refregier

O(N) methods are based on the decay properties of the density matrix in real space, an effect sometimes refered to as near-sightedness. We show, that in addition to this near-sightedness in real space there is also a near-sightedness in…

Condensed Matter · Physics 2007-05-23 S. Goedecker , O. V. Ivanov

Two approaches (micro- and macro- investigations) are used to determine the dimension dependences of the optical parameters of the nanometer-scale layers of materials. It is shown that both an index of refraction and coefficient of…

Materials Science · Physics 2016-10-13 T. A. Kudykina , A. I. Pervak

Fractal geometry proved to be an effective mathematical tool for exploring real geographical space based on digital maps and remote sensing images. Whether the fractal theory tool can be applied to abstract geographical space has not been…

Physics and Society · Physics 2023-06-06 Yanguang Chen

With the increasing growth of technology and the entrance into the digital age, we have to handle a vast amount of information every time which often presents difficulties. So, the digital information must be stored and retrieved in an…

Multimedia · Computer Science 2012-08-15 Kamrul Hasan Talukder , Koichi Harada

A giant planet embedded in a protoplanetary disk creates a gap. This process is important for both theory and observations. Using results of a survey for a wide parameter range with two-dimensional hydrodynamic simulations, we constructed…

Earth and Planetary Astrophysics · Physics 2017-12-20 K. D. Kanagawa , H. Tanaka , T. Muto , T. Tanigawa

Massive neutrinos influence the background evolution of the Universe as well as the growth of structure. Being able to model this effect and constrain the sum of their masses is one of the key challenges in modern cosmology. Weak-lensing…

Cosmology and Nongalactic Astrophysics · Physics 2021-01-06 Virginia Ajani , Austin Peel , Valeria Pettorino , Jean-Luc Starck , Zack Li , Jia Liu

The empirical wavelet transform is an adaptive multiresolution analysis tool based on the idea of building filters on a data-driven partition of the Fourier domain. However, existing 2D extensions are constrained by the shape of the…

Spectral Theory · Mathematics 2024-10-28 Basile Hurat , Zariluz Alvarado , Jerome Gilles