Abstract We show that two seemingly unrelated problems—the trapping of an atom in optical superlattice (OSL) and the libration a planar rigid rotor combined electric fields (PR) – have isomorphic Hamiltonians. Formed by interference lattices whose spatial periods differ factor two, OSL gives rise to periodic potential acts on atomic translation via AC Stark effect. The PR system, also known as ...

Spatial seemingly unrelated regression (spatial SUR) models are a useful multiequational econometric specification to simultaneously incorporate spatial effects and correlated error terms across equations. The purpose of the spsur R package is supply complete set functions test for structures in residual SUR model; estimate most popular specifications by applying different methods linear restri...

This paper considers the Ridge Feasible Generalized Least Squares Estimator (RFGLSE), Seemingly Unrelated Regression RSUR and proposes Kibria-Lukman KLSUR estimator for parameters of (SUR) model when regressors models are collinear. A simulation study was conducted to compare performance three different types estimators SUR model. Different correlation levels (0.0, 0.1, 0.2, ..., 0.9) among ind...

In recursive linear models, the multivariate normal joint distribution of all variables exhibits a dependence structure induced by a recursive (or acyclic) system of linear structural equations. These linear models have a long tradition and appear in seemingly unrelated regressions, structural equation modelling, and approaches to causal inference. They are also related to Gaussian graphical mo...

This paper proposes finite-sample procedures for testing the SURE specification in multi-equation regression models, i.e. whether the disturbances in different equations are contemporaneously uncorrelated or not. We apply the technique of Monte Carlo (MC) tests [Dwass (1957), Barnard (1963)] to obtain exact tests based on standard LR and LM zero correlation tests. We also suggest a MC quasi-LR ...

In this paper we advocate for the idea that two seemingly unrelated mysteries with almost 90 year history -- nature of dark matter and million-degree solar corona may be but sides same coin axions born in core Sun photons axion origin corona, whose modulations are controlled by anticorrelated modulation asymmetric (ADM) density interior.