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We calculate the wavelength dependence of the ratio of the linear polarization degree to extinction (polarizing efficiency) $P(\lambda)/A(\lambda)$ from the ultraviolet to near-infrared. The prolate and oblate particles with aspect ratios…

Astrophysics · Physics 2009-11-13 N. V. Voshchinnikov , H. K. Das

We demonstrate an approach to obtaining near quantum-limited far-field imaging resolution of incoherent sources with arbitrary distributions. Our method assumes no prior knowledge of the source distribution, but rather uses an adaptive…

Quantum Physics · Physics 2022-02-28 Erik F. Matlin , Lucas J. Zipp

Cosmological random fields are often analysed in spherical Fourier-Bessel basis. Compared to the Cartesian Fourier basis this has an advantage of properly taking into account some of the relevant physical processes (redshift-space…

Cosmology and Nongalactic Astrophysics · Physics 2019-06-17 Lado Samushia

Using the method of separation of variables and a new approach to calculations of the prolate spheroidal wave functions, we study the optical properties of very elongated (cigar-like) spheroidal particles. A comparison of extinction…

Astrophysics · Physics 2009-11-07 N V Voshchinnikov , V G Farafonov

A major challenge in flow through porous media is to better understand the link between microstructure and macroscale flow and transport. For idealised microstructures, the mathematical framework of homogenisation theory can be used for…

Propagation of light in nonlinear materials is here studied in the regime of the geometrical optics. It is shown that a spherically symmetric medium at rest with some specific dielectric properties can be used to produce an exact analogue…

General Relativity and Quantum Cosmology · Physics 2015-02-17 E. Bittencourt , V. A. De Lorenci , R. Klippert , M. Novello , J. M. Salim

By radiation transfer models with a realistic power spectra of the projected density distributions, we show that the optical properties of grains are poorly constrained by observations of reflection nebulae. The ISM is known to be…

Astrophysics · Physics 2009-11-07 John S. Mathis , Barbara A. Whitney , Kenneth Wood

We study two different methods for inferring the parameters of a spheroid distribution from planar sections of a stationary spatial system of spheroids: one method first unfolds non-parametrically the joint size-shape-orientation…

Methodology · Statistics 2018-03-09 Markus Baaske , Felix Ballani , Alexandra Illgen

Particle smoothing methods are used for inference of stochastic processes based on noisy observations. Typically, the estimation of the marginal posterior distribution given all observations is cumbersome and computational intensive. In…

Machine Learning · Computer Science 2017-05-24 H. -Ch. Ruiz , H. J. Kappen

Recent experimental work has demonstrated the potential to combine the merits of diffractive and on-chip photonic information processing devices in a single chip by making use of planar (or slab) waveguides. Researchers have adapted key…

Optics · Physics 2023-05-26 Benjamin Wetherfield , Timothy D. Wilkinson

In 1977 Berg & Purcell published a landmark paper entitled "Physics of Chemoreception" which examined how a bacterium can sense a chemical attractant in the fluid surrounding it. At small scales the attractant molecules move by Brownian…

Analysis of PDEs · Mathematics 2017-07-18 Andrew J. Bernoff , Alan E. Lindsay

The optical properties of rod-like two-layer nanoparticles are studied using the notions of equivalent prolate spheroid. The calculations are presented for frequency dependencies for polarizability and the absorption and scattering…

Optics · Physics 2024-07-02 Ya. V. Karandas

A simple, yet general, formalism for the optimized linear combination of astrophysical images is constructed and demonstrated. The formalism allows the user to combine multiple undersampled images to provide oversampled output at high…

Instrumentation and Methods for Astrophysics · Physics 2015-05-28 Barnaby Rowe , Christopher Hirata , Jason Rhodes

A method of modifying the roughness of soda-lime glass spheres is presented, with the purpose of tuning inter-particle friction. The effect of chemical etching on the surface topography and the bulk frictional properties of grains is…

Statistical Mechanics · Physics 2015-10-27 Sonia Utermann , Philipp Aurin , Markus Benderoth , Cornelius Fischer , Matthias Schröter

We provide a numerical algorithm for the model characterizing anomalous diffusion in expanding media, which is derived in [F. Le Vot, E. Abad, and S. B. Yuste, Phys. Rev. E {\bf96} (2017) 032117]. The Sobolev regularity for the equation is…

Numerical Analysis · Mathematics 2020-11-13 Daxin Nie , Jing Sun , Weihua Deng

Context. Dust grains coagulate to form dust aggregates in protoplanetary disks. Their porosity can be extremely high in the disks. Although disk emission may come from fluffy dust aggregates, the emission has been modeled with compact…

Earth and Planetary Astrophysics · Physics 2014-09-05 Akimasa Kataoka , Satoshi Okuzumi , Hidekazu Tanaka , Hideko Nomura

We perform simulations to evaluate a recent experimental technique for using in-line holographic microscopy and an effective-sphere model to measure the population-averaged fractal dimension $D_f$ of an ensemble of colloidal fractal…

Optics · Physics 2019-10-02 Jerome Fung , Samantha Hoang

Scattering and absorption properties at optical and ultraviolet wavelengths are calculated for an interstellar dust model consisting of carbonaceous grains and amorphous silicate grains. Polarization as a function of scattering angle is…

Astrophysics · Physics 2011-05-05 B. T. Draine

Spherical symmetry is ubiquitous in nature. It's therefore unfortunate that spherical system simulations are so hard, and require complete spheres with millions of interacting particles. Here we introduce an approach to model spherical…

Materials Science · Physics 2011-10-07 Pekka Koskinen , Oleg O. Kit

The sedimentation dynamics of a prolate spheroidal particle in an unbounded elastoviscoplastic (EVP) fluid is studied by direct finite element simulations under inertialess flow conditions. The Saramito-Giesekus constitutive equation is…

Fluid Dynamics · Physics 2024-03-25 Alie Abbasi Yazdi , Gaetano DAvino
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