Results 81 to 90 of about 22,331 (301)
f(R) theories of gravity in the Palatini approach matched with observations
General Relativity and Gravitation, 2006 We investigate the viability of f(R) theories in the framework of the Palatini approach as solutions to the problem of the observed accelerated expansion of the universe. Two physically motivated popular choices for f(R) are considered: power law, f(R) = βR^n, and logarithmic, f(R) = α\ln{R}.
CAPOZZIELLO, SALVATORE +2 more
openaire +6 more sources
Accelerating cosmology in modified gravity: From convenient F(R) or string-inspired theory to bimetric F(R) gravity [PDF]
International Journal of Geometric Methods in Modern Physics, 2014 We consider modified gravity which may describe the early-time inflation and/or late-time cosmic acceleration of the universe. In particular, we discuss the properties of F(R), F(G), string-inspired and scalar-Einstein–Gauss–Bonnet gravities, including their FRW equations and fluid or scalar-tensor description.
Nojiri, Shin'ichi, Odintsov, Sergei D.
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Advanced Materials, EarlyView.Oppositely charged single enzyme nanogels (SENs) phase‐separate into bi‐enzymatic coacervate microdroplets, acting as both scaffold and functional units. By tuning SEN ratios, these coacervates create specific microenvironments that enable selective small‐molecule enrichment and efficient intermediate diffusion.
Andoni Rodriguez‐Abetxuko +11 more
wiley +1 more source
Palatini formulation of the conformally invariant $$f\left( R,L_m\right) $$ f R , L m gravity theory
European Physical Journal C: Particles and Fields, 2022 We investigate the field equations of the conformally invariant models of gravity with curvature-matter coupling, constructed in Weyl geometry, using the Palatini formalism.
Tiberiu Harko, Shahab Shahidi
doaj +1 more source
Anisotropy effects on baryogenesis in f(R) theories of gravity [PDF]
Modern Physics Letters A, 2018 We study the f(R) theory of gravity in an anisotropic metric and its effect on the baryon number-to-entropy ratio. The mechanism of gravitational baryogenesis based on the CPT-violating gravitational interaction between derivative of the Ricci scalar curvature and the baryon-number current is investigated in the context of the f(R) gravity.
A. Aghamohammadi +2 more
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Advanced Materials, EarlyView.Inspired by the octopus and the golden wheel spider, soft robots with liquid crystal elastomer arc fibers as appendages are fabricated to transcend surface constraints through an elevated center of mass and minimal contact footprints. By leveraging curvature‐encoded deformation‐recovery cycles, these robots exhibit contractile, torsional, and flexural ...
Jong Bin Kim +5 more
wiley +1 more source
A complete cosmological scenario from $$f(R,T^{\phi })$$ f ( R , T ϕ ) gravity theory
, 2016 Recent elaborated by Harko et al., the f(R, T) theories of gravity allow one to contemplate an optimistic alternative to dark energy, for which R and T stand for the Ricci scalar and the trace of the energy-momentum tensor, respectively.
P. H. R. S. Moraes, J. R. L. Santos
core +1 more source
PALATINI APPROACH TO MODIFIED GRAVITY: f(R) THEORIES AND BEYOND [PDF]
International Journal of Modern Physics D, 2011 We review the recent literature on modified theories of gravity in the Palatini approach. After discussing the motivations that lead to consider alternatives to Einstein's theory and to treat the metric and the connection as independent objects, we review several topics that have been recently studied within this framework. In particular, we provide an
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Cosmological singularity theorems forf(R) gravity theories [PDF]
Journal of Cosmology and Astroparticle Physics, 2016 An improved version is published in JCAP 05 (2016 ...
Alani, Ivo Andrés +1 more
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Advanced Materials, EarlyView.A hierarchical hydrogel evaporator with a thin, porous photothermal layer of fused core–shell carbon‐polymer nanospheres enables ultrafast interfacial solar evaporation with minimized heat loss and sufficient water supply. Directional advection‐dominated brine transport, coupled with Marangoni‐driven interfacial flow, drives salt away from the active ...
Haokun Shen +11 more
wiley +1 more source