Results 81 to 90 of about 169,909 (330)
Generalized Ricci solitons and Einstein metrics on weak K-contact manifolds
Communications in Analysis and Mechanics, 2023 We study so-called "weak" metric structures on a smooth manifold, which generalize the metric contact and $ K $-contact structures and allow a new look at the classical theory.
Vladimir Rovenski
doaj +1 more source
Ambient connections realising conformal Tractor holonomy
, 2006 For a conformal manifold we introduce the notion of an ambient connection, an affine connection on an ambient manifold of the conformal manifold, possibly with torsion, and with conditions relating it to the conformal structure.
A Čap +10 more
core +3 more sources
The Einstein−Λ flow on product manifolds [PDF]
Classical and Quantum Gravity, 2016 We consider the vacuum Einstein flow with a positive cosmological constant on spatial manifolds of product form. In spatial dimension at least four we show the existence of continuous families of recollapsing models whenever at least one of the factors or admits a Riemannian Einstein metric with positive Einstein constant.
Klaus Kröncke, David Fajman
openaire +4 more sources
Advanced Energy Materials, EarlyView.Electrocatalysis of the oxygen evolution reaction (OER) is pivotal in production of hydrogen and further green fuels. Materials with bulk‐phase OER activity of the complete material or amorphized near‐surface regions are of prime application interest.
Shima Farhoosh +5 more
wiley +1 more source
On Compact Trans-Sasakian Manifolds
Advances in Mathematical Physics, 2022 We study 3-dimensional compact and simply connected trans-Sasakian manifolds and find necessary and sufficient conditions under which these manifolds are homothetic to Sasakian manifolds.
Ibrahim Al-Dayel, Sharief Deshmukh
doaj +1 more source
A New Infinite Class of Sasaki-Einstein Manifolds
, 2004 We show that for every positive curvature Kahler-Einstein manifold in dimension 2n there is a countably infinite class of associated Sasaki-Einstein manifolds X_{2n+3} in dimension 2n+3.
Gauntlett, Jerome P. +3 more
core +1 more source
Transport Resistance Dominates the Fill Factor Losses in Record Organic Solar Cells
Advanced Energy Materials, EarlyView.Organic photovoltaics are a promising solar cell technology, but even the record devices with 20% efficiency have significant fill factor losses due to low active layer conductivities. In this Perspective, the authors describe the origin of these losses, discuss experimental methods for their quantification, and explain how to minimize them to optimize
Chen Wang +6 more
wiley +1 more source
Stable and unstable Einstein warped products [PDF]
Trans. Amer. Math. Soc. 369 (2017) no. 9, 6537-6563, 2015 In this article, we systematically investigate the stability properties of certain warped product Einstein manifolds. We characterize stability of these metrics in terms of an eigenvalue condition of the Einstein operator on the base manifold. In particular, we prove that all complete manifolds carrying imaginary Killing spinors are strictly stable ...
arxiv +1 more source
Advanced Energy Materials, EarlyView.This concept article provides a comprehensive introduction and overview of how (fully) organic batteries and the respective redox‐active organic electrode materials work. Options for cell setups are discussed, as well as the difference between half‐ and full‐cells and the relevance of the two types. At the material level, the difference between organic
Robin Wessling +2 more
wiley +1 more source
Rigidity of Weak Einstein-Randers Spaces [PDF]
Sahand Communications in Mathematical AnalysisThe Randers metrics are popular metrics similar to the Riemannian metrics, frequently used in physical and geometric studies. The weak Einstein-Finsler metrics are a natural generalization of the Einstein-Finsler metrics.
Behnaz Lajmiri +2 more
doaj +1 more source