Results 51 to 60 of about 47,494 (299)

Lorentzian Quantum Cosmology from Effective Spin Foams

Universe
Effective spin foams provide the most computationally efficient spin foam models yet and are therefore ideally suited for applications, e.g., to quantum cosmology.
Bianca Dittrich, José Padua-Argüelles
doaj   +1 more source

The Feynman propagator for quantum gravity: spin foams, proper time, orientation, causality and timeless-ordering

, 2004
We discuss the notion of causality in Quantum Gravity in the context of sum-over-histories approaches, in the absence therefore of any background time parameter.
Oriti, Daniele
core   +4 more sources

On knottings in the physical Hilbert space of LQG as given by the EPRL model [PDF]

, 2010
We consider the EPRL spin foam amplitude for arbitrary embedded two-complexes. Choosing a definition of the face- and edge amplitudes which lead to spin foam amplitudes invariant under trivial subdivisions, we investigate invariance properties of the ...
Barrett J, Barrett J, Benjamin Bahr, Bianchi E Regoli D Rovelli C, Bojowald M Perez A, Edmonds A R, Freidel L, Freidel L Livine E, Freidel L Speziale S, Kaminski W, Kaminski W, Livine E, Noui K, Perez A, Rovelli C, Rovelli C, Rovelli C, Sahlmann H   +17 more
core   +1 more source

Cosmological deformation of Lorentzian spin foam models [PDF]

Classical and Quantum Gravity, 2003
We study the quantum deformation of the Barrett-Crane Lorentzian spin foam model which is conjectured to be the discretization of Lorentzian Plebanski model with positive cosmological constant and includes therefore as a particular sector quantum gravity in de-Sitter space.
Roche, Philippe, Noui, K.
openaire   +3 more sources

Hands‐on protocol for preparing water‐soluble fractions from agri‐food samples for NMR‐based metabolomics analysis

FEBS Open Bio, EarlyView.
This research protocol outlines a workflow for nuclear magnetic resonance (NMR)‐based metabolomics in the agri‐food sector. Using two case studies—strawberry leaves (solid matrix) and wine (liquid matrix)—it details the procedures for sample preparation, data acquisition, and processing.
Andrea Fernández‐Veloso, Jaime Hiniesta‐Valero, Alejandra Guerra‐Castellano, Miguel A. De la Rosa, Irene Díaz‐Moreno   +4 more
wiley   +1 more source

Spin foam models for quantum gravity [PDF]

Classical and Quantum Gravity, 2003
In this article we review the present status of the spin foam formulation of non-perturbative (background independent) quantum gravity. The article is divided in two parts. In the first part we present a general introduction to the main ideas emphasizing their motivations from various perspectives.
openaire   +2 more sources

A New Spin Foam Model for 4d Gravity

, 2008
Starting from Plebanski formulation of gravity as a constrained BF theory we propose a new spin foam model for 4d Riemannian quantum gravity that generalises the well-known Barrett-Crane model and resolves the inherent to it ultra-locality problem.
Alexandrov S, Ashtekar A, Baez J C, Baez J C, Baratin A, Barrett J W, Barrett J W, Buffenoir E, Capovilla R, De Pietri R, Engle J Livine E Pereira R Rovelli C, Engle J Pereira R Rovelli C, Freidel L, Freidel L, Freidel L, Gelfand I M, Kirill Krasnov, Laurent Freidel, Livine E R Speziale S, Perelomov A, Ponzano G, Reisenberger M P, Reisenberger M P   +22 more
core   +1 more source

Altered Dynamic Functional Network Connectivity in Post‐Stroke Aphasia

Annals of Clinical and Translational Neurology, EarlyView.
ABSTRACT Objective Previous studies examining post‐stroke aphasia (PSA) patients via resting‐state functional magnetic resonance imaging (rs‐fMRI) have predominantly focused on static functional connectivity. In contrast, the current investigation aims to elucidate the alterations in dynamic functional network connectivity (dFNC) among PSA patients ...
Guihua Xu, Yongsheng Wu, Junyu Qu, Rui Zhu, Wenwen Xu, Jiaxiang Xin, Dawei Wang   +6 more
wiley   +1 more source

Numerical Evaluation of Spin Foam Amplitudes beyond simplices [PDF]

, 2022
Courtney Allen, Florian Girelli, Sebastian Steinhaus   +2 more
openalex   +3 more sources

Effect of Foot Orthoses on Midfoot Pain and the Volume of Bone Marrow Lesions in the Midfoot: A Randomized Mechanism of Action Study

Arthritis Care &Research, EarlyView.
Objective Foot orthoses are thought to improve pain by potentially modifying internal mechanical forces. To test this, we explored whether foot orthoses can modify patterns of bone marrow lesions (BMLs) in people with midfoot pain. Methods Forty‐two people were recruited with midfoot pain, and magnetic resonance imaging–confirmed midfoot BMLs ...
Jill Halstead, Anne‐Maree Keenan, Philip G. Conaghan, Dennis McGonagle, Anthony C. Redmond   +4 more
wiley   +1 more source