Results 61 to 70 of about 46,248 (301)

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

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   +3 more sources

Copper‐based Materials for Photo and Electrocatalytic Process: Advancing Renewable Energy and Environmental Applications

Advanced Functional Materials, EarlyView.
Cu‐based catalysts as a cornerstone in advancing sustainable energy technologies are fully reviewed in this manuscript, highlighting their potential in photo‐ and electrocatalysis. It includes metallic copper, copper oxides, copper sulfides, copper halide perovskites, copper‐based metal–organic frameworks (MOFs), and covalent organic frameworks (COFs),
Jéssica C. de Almeida, Yanjie Wang, Thais A. Rodrigues, Paulo H. H. Nunes, Vagner R. de Mendonça, Paulo H. E. Falsetti, Leticia V. Savazi, Tao He, Alexandra V. Bardakova, Aida V. Rudakova, Jie Tian, Alexei V. Emeline, Osmando F. Lopes, Antonio Otavio T. Patrocínio, Jia Hong Pan, Caue Ribeiro, Detlef W. Bahnemann   +16 more
wiley   +1 more source

Battery‐Free, Wireless Multi‐Sensing Platform for Comprehensive Management of Pressure Injury and Hygiene

Advanced Functional Materials, EarlyView.
A battery‐free, wireless device for real‐time monitoring of pressure injury and hygiene integrates pressure (≈10 kPa), temperature (≈40 °C), and NH3 gas sensing with antibacterial functionality. Enabled by near‐field communication, it ensures simultaneous, interference‐free mechanical and chemical monitoring, offering a practical solution for pressure ...
Myungwoo Choi, Sunwoo Lee, Sang Won Kim, Ji Yeon Lee, Younghan Kim, Jewook Kim, Gye Hyeon Lee, Saehan Choi, Seonggwang Yoo, Hak‐Young Ahn, Taehoon Kim, Je‐Sang Lee, Weon Gi Min, Inkyu Park, Young‐Seok Shim, Yoon Sung Nam, Seokwoo Jeon, Jeong‐O Lee, Yong Suk Oh, Donghwi Cho   +19 more
wiley   +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   +5 more sources

Tailored Reconstruction of Polycrystalline CuO Nanorods Promotes C─C Coupling in CO2 Electroreduction

Advanced Functional Materials, EarlyView.
Controlling the polycrystallinity of CuO nanorods enables directional reconstruction into rod‐like structures that stabilize Cu(OH)2 and increase Cu+ ratios, while modulating interfacial water dynamics to enhance C─C coupling and boost C2+ product formation in CO2 electroreduction.
Hyeon‐Seok Bang, Young‐Jin Ko, Hyo Sang Jeon, Eugene Huh, Eung Dab Kim, Min Gwan Ha, Chulwan Lim, Jiho Jeon, Seohyeon Ka, Dogyeong Kim, Xiaojie Zhang, Yeongjin Kim, Kyeongsu Kim, Woong Hee Lee, Jae‐Young Choi, Hyung‐Suk Oh   +15 more
wiley   +1 more source

Non-geometric Kaluza-Klein monopoles and magnetic duals of M-theory R-flux backgrounds

Journal of High Energy Physics, 2017
We introduce a magnetic analogue of the seven-dimensional nonassociative octonionic R-flux algebra that describes the phase space of M2-branes in four-dimensional locally non-geometric M-theory backgrounds.
Dieter Lüst, Emanuel Malek, Richard J. Szabo   +2 more
doaj   +1 more source

Hidden Quantum Gravity in 3d Feynman diagrams

, 2006
In this work we show that 3d Feynman amplitudes of standard QFT in flat and homogeneous space can be naturally expressed as expectation values of a specific topological spin foam model.
Aristide Baratin, Baez J C, Baratin A, Barrett J W, Barrett J W Garcia-Islas J M Martins J F, Freidel L, Freidel L, Freidel L, Freidel L, Freidel L Livine E R, Freidel L Livine E R, Freidel L Louapre D, Freidel L Majid S, Freidel L Starodubtsev A, Laurent Freidel, Noui K, Oriti D, Perez A, Polyakov A M, Ponzano G, Regge T, Singer I M, Taylor Y U Woodward C T   +22 more
core   +1 more source

Geometrically Templated, Ultra‐Lightweight and High Strength Soap Films from Lyotropic Liquid Crystalline Graphene Oxide/Polymer Composites

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, Yuchong Gao, Mostafa Akbari, Kun‐Hao Yu, Kun‐Yu Wang, Mohit Patel, Shouhong Fan, Ziyun Zhang, Masoud Akbarzadeh, Shu Yang   +9 more
wiley   +1 more source

Testing the imposition of the spin foam simplicity constraints [PDF]

Classical and Quantum Gravity, 2012
We introduce a three-dimensional Plebanski action for the gauge group SO(4). In this model, the $B$ field satisfies quadratic simplicity constraints similar to that of the four-dimensional Plebanski theory, but with the difference that the $B$ field is now a one-form. We exhibit a natural notion of "simple one-form", and identify a gravitational sector,
Marc Geiller, Karim Noui, Karim Noui
openaire   +5 more sources