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Electron-positron clusters are studied using a quantum hydrodynamic model that includes Coulomb and exchange interactions. A variational Lagrangian method is used to determine their stationary and dynamical properties. The cluster static…

Plasma Physics · Physics 2012-12-03 Giovanni Manfredi , Paul-Antoine Hervieux , Fernando Haas

We present the methodology for deriving accurate and reliable cosmological constraints from non-linear scales (<50Mpc/h) with k-th nearest neighbor (kNN) statistics. We detail our methods for choosing robust minimum scale cuts and…

Cosmology and Nongalactic Astrophysics · Physics 2023-10-11 Sihan Yuan , Tom Abel , Risa H. Wechsler

We present a novel approach, based entirely on the gravitational potential, for studying the evolution of non-linear cosmological matter perturbations. Starting from the perturbed Einstein equations, we integrate out the non-relativistic…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 Ram Brustein , Antonio Riotto

Local nonlinear approximations to the growth of cosmic perturbations are developed, resulting in relations, at a given epoch, between the peculiar velocity and gravity fields and their gradients. Only the equation of motion is approximated,…

Astrophysics · Physics 2009-10-22 Paul J. Mancinelli , Amos Yahil

We develop a theory of nonlinear cosmological perturbations on superhorizon scales where a characteristic length scale of perturbations is longer than the Hubble radius, in general theoretical frameworks. Our formalism is based on the…

General Relativity and Quantum Cosmology · Physics 2018-04-24 Yu-ichi Takamizu

We show that the formation of large-scale structures through gravitational instability in the expanding universe can be fully described through a path-integral formalism. We derive the action S[f] which gives the statistical weight…

Astrophysics · Physics 2009-11-10 P. Valageas

Population structure can have a significant effect on evolution. For some systems with sufficient symmetry, analytic results can be derived within the mathematical framework of evolutionary graph theory which relate to the outcome of the…

Populations and Evolution · Quantitative Biology 2019-03-11 Christopher E. Overton , Mark Broom , Christoforos Hadjichrysanthou , Kieran J. Sharkey

In many practical applications of clustering, the objects to be clustered evolve over time, and a clustering result is desired at each time step. In such applications, evolutionary clustering typically outperforms traditional static…

Machine Learning · Computer Science 2015-03-19 Kevin S. Xu , Mark Kliger , Alfred O. Hero

There have been rapid developments in model-based clustering of graphs, also known as block modelling, over the last ten years or so. We review different approaches and extensions proposed for different aspects in this area, such as the…

Machine Learning · Statistics 2020-01-01 Clement Lee , Darren J Wilkinson

I present a general discussion of the evolution and model-dependence of both the linear and nonlinear power spectrum of density fluctuations. The features of the linear power spectrum in cosmological models with cold dark matter (CDM) and…

Astrophysics · Physics 2009-10-31 Chung-Pei Ma

This paper investigates whether nonlinear gravitational instability can account for the clustering of galaxies on large and small scales, and for the evolution of clustering with epoch. No CDM-like spectrum is consistent with the shape of…

Astrophysics · Physics 2015-06-24 J. A. Peacock

The adhesion model has been proposed in the past as an improvement of the Zel'dovich approximation, providing a good description of the formation of the cosmic web. We recast the model as a field theory for cosmological large scale…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-19 Gerasimos Rigopoulos

The mass and spin distributions of compact binary gravitational-wave sources are currently uncertain due to complicated astrophysics involved in their formation. Multiple sub-populations of compact binaries representing different…

High Energy Astrophysical Phenomena · Physics 2019-07-24 Jade Powell , Simon Stevenson , Ilya Mandel , Peter Tino

Using a non-perturbative method developed in a previous work (paper II), we derive the probability distribution $P(\delta_R)$ of the density contrast within spherical cells in the quasi-linear regime for some non-Gaussian initial…

Astrophysics · Physics 2009-11-06 P. Valageas

Clustering methods seek to partition data such that elements are more similar to elements in the same cluster than to elements in different clusters. The main challenge in this task is the lack of a unified definition of a cluster,…

Statistics Theory · Mathematics 2022-07-06 Franz Besold , Vladimir Spokoiny

Multiscale dynamics are ubiquitous in applications of modern science. Because of time scale separation between relatively small set of slowly evolving variables and (typically) much larger set of rapidly changing variables, direct numerical…

Dynamical Systems · Mathematics 2016-04-08 Rafail V. Abramov

Observations of galaxy clusters (GC's) are a powerful tool to probe the evolution of the Universe at $z<2$. However, the determination of their real shape and structure is not completely understood and the assumption of asphericity is often…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-19 R. F. L. Holanda , J. S. Alcaniz

Using an ensemble of high resolution 2D numerical simulations, we explore the scaling properties of cosmological density fluctuations in the non-linear regime. We study the scaling behaviour of the usual $N$--point volume-averaged…

Astrophysics · Physics 2009-10-30 D. Munshi , L. Y. Chiang , P. Coles , A. L. Melott

Dynamic model reduction in power systems is necessary for improving computational efficiency. Traditional model reduction using linearized models or online analysis is not adequate to capture dynamic behaviors of the power system,…

This paper deals with nonparametric estimation of conditional den-sities in mixture models in the case when additional covariates are available. The proposed approach consists of performing a prelim-inary clustering algorithm on the…

Statistics Theory · Mathematics 2015-02-09 Stéphane Auray , Nicolas Klutchnikoff , Laurent Rouvière