Results 71 to 80 of about 47,494 (299)
On the Expansions in Spin Foam Cosmology [PDF]
Physical Review D, 2011 We discuss the expansions used in spin foam cosmology. We point out that already at the one vertex level arbitrarily complicated amplitudes contribute, and discuss the geometric asymptotics of the five simplest ones. We discuss what type of consistency conditions would be required to control the expansion.
openaire +4 more sources
Quantum group spin nets: refinement limit and relation to spin foams
, 2014 So far spin foam models are hardly understood beyond a few of their basic building blocks. To make progress on this question, we define analogue spin foam models, so called spin nets, for quantum groups $\text{SU}(2)_k$ and examine their effective ...
Dittrich, Bianca +2 more
core +1 more source
Advanced Functional Materials, EarlyView.Shellular materials form spontaneously by dip coating the primitive triply periodic minimal surface (TPMS) wireframe in an aqueous solution of lyotropic liquid crystalline graphene oxide (GO) nanosheets mixed with polymers. Regulated by surface tension, GO nanosheets align on the polymer soap film as the stress builds up during drying.
Yinding Chi +9 more
wiley +1 more source
Discrete Gravity Models and Loop Quantum Gravity: a Short Review
Symmetry, Integrability and Geometry: Methods and Applications, 2012 We review the relation between Loop Quantum Gravity on a fixed graph and discrete models of gravity. We compare Regge and twisted geometries, and discuss discrete actions based on twisted geometries and on the discretization of the Plebanski action.
Simone Speziale +2 more
doaj +1 more source
Demonstration of Focusing Wolter Mirrors for Neutron Phase and Magnetic Imaging
Journal of Imaging, 2018 Image-forming focusing mirrors were employed to demonstrate their applicability to two different modalities of neutron imaging, phase imaging with a far-field interferometer, and magnetic-field imaging through the manipulation of the neutron beam ...
Daniel S. Hussey +7 more
doaj +1 more source
Effective action and semiclassical limit of spin foam models
, 2011 We define an effective action for spin foam models of quantum gravity by adapting the background field method from quantum field theory. We show that the Regge action is the leading term in the semi-classical expansion of the spin foam effective action ...
A Miković +16 more
core +1 more source
Advanced Functional Materials, EarlyView.Copper catalysts introduced with different non‐metallic elements regulating the coordination number of Cu are prepared by magnetron sputtering. Reducing the Cu coordination number enhances C─C coupling and boosts C2+ product selectivity, by lowering the energy barrier for the *CO → *CHO conversion step. The optimized Si‐doped Cu catalyst achieves a C2+
Xiaoye Du +8 more
wiley +1 more source
Holonomy Spin Foam Models: Definition and Coarse Graining
, 2012 We propose a new holonomy formulation for spin foams, which naturally extends the theory space of lattice gauge theories. This allows current spin foam models to be defined on arbitrary two-complexes as well as to generalize current spin foam models to ...
Bahr, Benjamin +3 more
core +1 more source
Design and Applications of Multi‐Frequency Programmable Metamaterials for Adaptive Stealth
Advanced Functional Materials, EarlyView.This article provides a comprehensive overview of metamaterials, including their fundamental principles, properties, synthesis techniques, and applications in stealth, as well as their challenges and future prospects. It covers topics that are more advanced than those typically discussed in existing review articles, while still being closely connected ...
Jonathan Tersur Orasugh +4 more
wiley +1 more source