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The well-known Lagrangian of current superfluid systems is not relativistic covariant, this paper gives a general relativistic covariant Lagrangian of superfluid systems, and naturally finds the non-relativistic Lagrangian and its all…

General Physics · Physics 2017-07-18 Jia-Min Yuan , Yong-Chang Huang

We measure shifts of the acoustic scale due to nonlinear growth and redshift distortions to a high precision using a very large volume of high-force-resolution simulations. We compare results from various sets of simulations that differ in…

We present an iterative method to reconstruct the linear-theory initial conditions from the late-time cosmological matter density field, with the intent of improving the recovery of the cosmic distance scale from the baryon acoustic…

Cosmology and Nongalactic Astrophysics · Physics 2018-11-05 Ryuichiro Hada , Daniel J. Eisenstein

The reconstruction of smooth density fields from scattered data points is a procedure that has multiple applications in a variety of disciplines, including Lagrangian (particle-based) models of solute transport in fluids. In random walk…

Computational Physics · Physics 2019-09-04 Guillem Sole-Mari , Diogo Bolster , Daniel Fernàndez-Garcia , Xavier Sanchez-Vila

We derive cosmological constraints from the probability distribution function (PDF) of evolved large-scale matter density fluctuations. We do this by splitting lines of sight by density based on their count of tracer galaxies, and by…

We introduce Lagrangian Flow Networks (LFlows) for modeling fluid densities and velocities continuously in space and time. By construction, the proposed LFlows satisfy the continuity equation, a PDE describing mass conservation in its…

Machine Learning · Computer Science 2023-12-15 F. Arend Torres , Marcello Massimo Negri , Marco Inversi , Jonathan Aellen , Volker Roth

Density-based distances (DBDs) provide a principled approach to metric learning by defining distances in terms of the underlying data distribution. By employing a Riemannian metric that increases in regions of low probability density,…

Machine Learning · Computer Science 2025-06-02 Peter Sorrenson , Daniel Behrend-Uriarte , Christoph Schnörr , Ullrich Köthe

We propose a new smoothing method for obtaining surface densities from discrete particle positions from numerical simulations. This is an essential step for many applications in gravitational lensing. This method is based on the ``scatter''…

Astrophysics · Physics 2011-02-11 Guo-Liang Li , S. Mao , Y. P. Jing , X. Kang , M. Bartelmann

Understanding, quantifying and controlling transport and mixing processes are central in the study of fluid flows. Many different Lagrangian approaches have been proposed for detecting organizing flow structures that determine material…

Fluid Dynamics · Physics 2026-04-17 Anna Klünker , Alexandra von Kameke , Kathrin Padberg-Gehle

The physical position is crucial in location-aware services or protocols based on geographic information, where localization is performed given a set of sensor measurements for acquiring the position of an object with respect to a certain…

Applications · Statistics 2022-04-14 Wu Junfeng , Mu Biqiang , Yi Xinlei , Wei Jieqiang , Johansson Karl Henrik

We present a method for reconstructing cosmological densityn for and velocity fields using the Lagrangian Zel'dovich formalism. . The method involves finding the least action solution for straight line particle paths in an evolving density…

Astrophysics · Physics 2015-06-24 R. A. C. Croft , E. Gaztanaga

Using third-order perturbation theory, we derive a relation between the mean divergence of the peculiar velocity given density and the density itself. Our calculations assume Gaussian initial conditions and are valid for Gaussian filtering…

Astrophysics · Physics 2015-06-24 Michal Chodorowski , Ewa Lokas , Agnieszka Pollo , Adi Nusser

The displacement field in highly non uniformly strained crystals is obtained by addition of constraints to an iterative phase retrieval algorithm. These constraints include direct space density uniformity and also constraints to the sign…

Materials Science · Physics 2009-11-11 A. A. Minkevich , M. Gailhanou , J. -S. Micha , B. Charlet , V. Chamard , O. Thomas

We present a formalism to compute Lagrangian displacement fields for a wide range of cosmologies in the context of perturbation theory up to third order. We emphasize the case of theories with scale dependent gravitational strengths, such…

Cosmology and Nongalactic Astrophysics · Physics 2018-01-16 Alejandro Aviles , Jorge L. Cervantes-Cota

The lecture notes describe the Delaunay Tessellation Field Estimator for Cosmic Web analysis. The high sensitivity of Voronoi/Delaunay tessellations to the local point distribution is used to obtain estimates of density and related…

Astrophysics · Physics 2017-03-08 Rien van de Weygaert , Willem Schaap

We compare different nonlinear approximations to gravitational clustering in the weakly nonlinear regime, using as a comparative statistic the evolution of non-Gaussianity which can be characterised by a set of numbers $S_p$ describing…

Astrophysics · Physics 2009-10-22 Dipak Munshi , Varun Sahni , Alexei A. Starobinsky

Encoding the distance between locations in space is essential for accurate navigation. Grid cells, a functional class of neurons in medial entorhinal cortex, are believed to support this computation. However, existing theories of how…

Neurons and Cognition · Quantitative Biology 2025-11-12 Pritipriya Dasbehera , Akshunna S. Dogra , William T. Redman

We study the effect of turbulence on a sedimenting layer of particles by means of direct numerical simulations. A Lagrangian model in which particles are considered as tracers with an additional downward settling velocity is integrated…

Fluid Dynamics · Physics 2020-07-08 Alessandro Sozza , Gabor Drotos , Emilio Hernández-García , Cristóbal López

Producing thousands of simulations of the dark matter distribution in the Universe with increasing precision is a challenging but critical task to facilitate the exploitation of current and forthcoming cosmological surveys. Many inexpensive…

Cosmology and Nongalactic Astrophysics · Physics 2023-02-02 Davide Piras , Benjamin Joachimi , Francisco Villaescusa-Navarro

We present a self-consistent Bayesian formalism to sample the primordial density fields compatible with a set of dark matter density tracers after cosmic evolution observed in redshift space. Previous works on density reconstruction did not…

Cosmology and Nongalactic Astrophysics · Physics 2019-07-09 E. G. Patrick Bos , Francisco-Shu Kitaura , Rien van de Weygaert
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