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Gravitational microlensing has proven to be a powerful tool in the study of quasars, providing some of the strongest limits on the scales of structure in the central engine. Typically sources are considered to be smoothly varying on some…

Astrophysics · Physics 2009-11-10 Geraint F. Lewis

Recent attempts to constrain cosmological variation in the fine structure constant, alpha, using quasar absorption lines have yielded two statistical samples which initially appear to be inconsistent. One of these samples was subsequently…

Cosmology and Nongalactic Astrophysics · Physics 2009-10-16 Julian A. King , Daniel J. Mortlock , John K. Webb , Michael T. Murphy

We review recent activity searching for variations in the fundamental constants of nature in quasar absorption spectra and in the laboratory. While research in this direction has been ongoing for many decades, the topic has recently been…

Atomic Physics · Physics 2011-02-02 J. C. Berengut , V. V. Flambaum

We investigate Monte Carlo energy and variance minimization techniques for optimizing many-body wave functions. Several variants of the basic techniques are studied, including limiting the variations in the weighting factors which arise in…

Condensed Matter · Physics 2009-10-31 P. R. C. Kent , R. J. Needs , G. Rajagopal

We study the covariance of the cross-power spectrum of different tracers for the large-scale structure. We develop the counts-in-cells framework for the multi-tracer approach, and use this to derive expressions for the full non-Gaussian…

Astrophysics · Physics 2015-05-13 Robert E. Smith

Understanding statistical inference under possibly non-sparse high-dimensional models has gained much interest recently. For a given component of the regression coefficient, we show that the difficulty of the problem depends on the sparsity…

Statistics Theory · Mathematics 2022-08-22 Jelena Bradic , Jianqing Fan , Yinchu Zhu

We introduce a new procedure for testing the significance of a set of regression coefficients in a Gaussian linear model with $n \geq d$. Our method, the $L$-test, provides the same statistical validity guarantee as the classical $F$-test,…

Methodology · Statistics 2025-12-01 Danielle Paulson , Souhardya Sengupta , Lucas Janson

Neutron stars are a prime laboratory for testing physical processes under conditions of strong gravity, high density, and extreme magnetic fields. Among the zoo of neutron star phenomena, magnetars stand out for their bursting behaviour,…

High Energy Astrophysical Phenomena · Physics 2015-09-16 D. Huppenkothen , B. J. Brewer , D. W. Hogg , I. Murray , M. Frean , C. Elenbaas , A. L. Watts , Y. Levin , A. J. van der Horst , C. Kouveliotou

(Abridged) Combining cosmic shear power spectra and cluster counts is powerful to improve cosmological parameter constraints and/or test inherent systematics. However they probe the same cosmic mass density field, if the two are drawn from…

Astrophysics · Physics 2009-06-23 Masahiro Takada , Sarah Bridle

It is a common saying that testing for conditional independence, i.e., testing whether whether two random vectors $X$ and $Y$ are independent, given $Z$, is a hard statistical problem if $Z$ is a continuous random variable (or vector). In…

Statistics Theory · Mathematics 2022-03-25 Rajen D. Shah , Jonas Peters

Composite likelihood inference has gained much popularity thanks to its computational manageability and its theoretical properties. Unfortunately, performing composite likelihood ratio tests is inconvenient because of their awkward…

Computation · Statistics 2014-08-01 Manuela Cattelan , Nicola Sartori

The prevalence of multivariate space-time data collected from monitoring networks and satellites, or generated from numerical models, has brought much attention to multivariate spatio-temporal statistical models, where the covariance…

Methodology · Statistics 2023-03-14 Huang Huang , Ying Sun , Marc G. Genton

The preferential sampling of locations chosen to observe a spatio-temporal process has been identified as a major problem across multiple fields. Predictions of the process can be severely biased when standard statistical methodologies are…

Methodology · Statistics 2020-03-05 Joe Watson

We discuss the effects of finite sky coverage and the uncertainty in extracting information about the power spectrum from experiments on small angular scales. In general the cosmic variance is enhanced by a factor of $4\pi/A$, where $A$ is…

Astrophysics · Physics 2009-10-22 Douglas Scott , Mark Srednicki , Martin White

Radial-velocity (RV) signals induce RV variations an order of magnitude larger than the signal created by the orbit of Earth-twins, thus preventing their detection. The goal of this paper is to compare the efficiency of the different…

P values or risk ratios from multiple, independent studies, observational or randomized, can be computationally combined to provide an overall assessment of a research question in meta-analysis. There is a need to examine the reliability of…

Methodology · Statistics 2021-10-28 S. Stanley Young , Warren B. Kindzierski

In this work, we investigate the fidelity of orbital optimization in variational Monte Carlo to improve diffusion Monte Carlo results on correlated magnetic systems, using CrSBr as a model system. We compare the performance of different…

Strongly Correlated Electrons · Physics 2026-04-27 Cody A. Melton , Jaron T. Krogel

We measure quasar variability using the Panoramic Survey Telescope and Rapid Response System 1 Survey (Pan-STARRS1 or PS1) and the Sloan Digital Sky Survey (SDSS) and establish a method of selecting quasars via their variability in 10,000…

We present variability and multi-wavelength photometric information for the 933 known quasars in the QUEST Variability Survey. These quasars are grouped into variable and non-variable populations based on measured variability confidence…

Astrophysics · Physics 2008-11-26 Adam W. Rengstorf , Robert J. Brunner , Brian C. Wilhite

Determining the relevant spatial covariates is one of the most important problems in the analysis of point patterns. Parametric methods may lead to incorrect conclusions, especially when the model of interactions between points is wrong.…

Methodology · Statistics 2022-10-12 Jiří Dvořák , Tomáš Mrkvička