Results 71 to 80 of about 63,399 (238)

Algebraic classification of spacetimes using discriminating scalar curvature invariants [PDF]

open access: yes, 2010
The Weyl and Ricci tensors can be algebraically classified in a Lorentzian spacetime of arbitrary dimensions using alignment theory. Used in tandem with the boost weight decomposition and curvature operators, the algebraic classification of the Weyl ...
Coley, Alan, Hervik, Sigbjorn
core  

Ricci Tensor Of Diagonal Metric

open access: yes, 1996
Efficient formulae of Ricci tensor for an arbitrary diagonal metric are presented.
openaire   +2 more sources

Sasakian Manifold and *-Ricci Tensor

open access: yes, 2018
The purpose of this paper is to study *-Ricci tensor on Sasakian manifold. Here, -confomally flat and confomally flat *- -Einstein Sasakian manifold are studied. Next, we consider *-Ricci symmetric conditon on Sasakian manifold. Finally, we study a special type of metric called *-Ricci soliton on Sasakian manifold.
Venkatesha., H, Aruna Kumara
openaire   +2 more sources

A complex network perspective on brain disease

open access: yesBiological Reviews, Volume 101, Issue 1, Page 364-399, February 2026.
ABSTRACT If brain anatomy and dynamics have a complex network structure as it has become standard to posit, it is reasonable to assume that such a structure should play a key role not only in brain function but also in brain dysfunction. However, exactly how network structure is implicated in brain damage and whether at least some pathologies can be ...
David Papo, Javier M. Buldú
wiley   +1 more source

Certain results on tangent bundle endowed with generalized Tanaka Webster connection (GTWC) on Kenmotsu manifolds

open access: yesAIMS Mathematics
This work studies the complete lifts of Kenmotsu manifolds associated with the generalized Tanaka-Webster connection (GTWC) in the tangent bundle.
Rajesh Kumar   +3 more
doaj   +1 more source

Stimuli‐Responsive Chemical Systems That Mimic Biological Dynamics

open access: yesChemistry – A European Journal, Volume 32, Issue 1, 2 January 2026.
Chemists are designing synthetic systems that mimic life's dynamic behaviors, such as motion, sensing, adaptation, and compartmentalization, by integrating reaction networks with stimuli like light, pH, and chemical fuels. This mini‐review surveys molecular machines, responsive materials, nucleic acid networks, and artificial cells, highlighting how ...
Antonio Aguanell   +3 more
wiley   +1 more source

Coordinate‐ and Spacetime‐Independent Quantum Physics

open access: yesAnnalen der Physik, Volume 538, Issue 1, January 2026.
This article studies in the framework of quantum field theory in curved spacetime, if there exists a single zero‐rank‐tensor solution of a Klein‐Gordon PDE, being valid at once for the depicted spacetimes. The answer is shown to be affirmative, even for a class of such solutions having the standard applications in particle physics. ABSTRACT The concept
Viacheslav A. Emelyanov, Daniel Robertz
wiley   +1 more source

Decomposition of geometric perturbations

open access: yes, 2008
For an infinitesimal deformation of a Riemannian manifold, we prove that the scalar, vector, and tensor modes in decompositions of perturbations of the metric tensor, the scalar curvature, the Ricci tensor, and the Einstein tensor decouple if and only if
Arnowitt   +9 more
core   +1 more source

Quantum GraviElectro Dynamics

open access: yesAnnalen der Physik, Volume 538, Issue 1, January 2026.
The BRST invariant Lagrangian of the gravitationally interacting U(1)$U(1)$ gauge theory, namely the Quantum GraviElectro Dynamics (QGED). The Yan–Mills theory with the Hilbert–Einstein gravitational Lagrangian, namely the Yang–Mills–Utiyama (YMU) theory, is defined and quantised using the standard procedure. The theory is perturbatively renormalisable,
Yoshimasa Kurihara
wiley   +1 more source

Closed time-like curves in f(R,A) modified gravity theory

open access: yesNuclear Physics B
In this manuscript, we investigate solutions that allow closed time-like curves (CTCs) in general relativity (GR) within the framework of a modified gravity theory. We consider here an alternative theory recently proposed in gravity theories known as f(R,
F. Ahmed, J.C.R. de Souza, A.F. Santos
doaj   +1 more source

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