Results 81 to 90 of about 46,248 (301)

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, Abbot L, Baez J C, Barrett J W, Barrett J W, Barrett J W Dowdall R J Fairbairn W J Hellmann F Pereira R, Bianchi E, Fairbairn W Meusburger C, Freidel L, M Vojinović, Magliaro E, Makela J, Miković A, Miković A, Miković A, Miković A Vojinović M, Miković A Vojinović M   +16 more
core   +1 more source

State‐of‐the‐Art, Insights, and Perspectives for MOFs‐Nanocomposites and MOF‐Derived (Nano)Materials

Advanced Materials, EarlyView.
Different approaches to MOF‐NP composite formation, such as ship‐in‐a‐bottle, bottle‐around‐the‐ship and in situ one‐step synthesis, are used. Owing to synergistic effects, the advantageous features of the components of the composites are beneficially combined, and their individual drawbacks are mitigated.
Stefanos Mourdikoudis, Subhajit Dutta, Saqib Kamal, Sergio Gómez‐Graña, Isabel Pastoriza‐Santos, Stefan Wuttke, Lakshminarayana Polavarapu   +6 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, Dittrich, Bianca, Hellmann, Frank, Kaminski, Wojciech   +3 more
core   +1 more source

Loop quantum cosmology and spin foams

Physics Letters B, 2009
Loop quantum cosmology (LQC) is used to provide concrete evidence in support of the general paradigm underlying spin foam models (SFMs). Specifically, it is shown that: i) the physical inner product in the timeless framework equals the transition amplitude in the deparameterized theory; ii) this quantity admits a %convergent vertex expansion a la SFMs ...
Miguel Campiglia, Abhay Ashtekar, Adam Henderson   +2 more
openaire   +3 more sources

Pioneering the Future: Principles, Advances, and Challenges in Organic Electrodes for Aqueous Ammonium‐Ion Batteries

Advanced Materials, Volume 37, Issue 13, April 2, 2025.
Leveraging the numerous advantages of ammonium‐ion (NH₄⁺)—including cost‐effectiveness, low corrosiveness, preferential orientation, and rapid diffusion kinetics—aqueous NH₄⁺ batteries (AAIBs) have gained significant attention. This review highlights and evaluates the progress of AAIBs utilizing organic electrode materials such as small molecules ...
Mangmang Shi, Xiaoyan Zhang
wiley   +1 more source

Plaque‐Targeted Delivery of Fluoride‐Free MXene Nanozyme for Alleviating Atherosclerosis via Sonocatalytic Therapy

Advanced Materials, EarlyView.
This work has developed a dual enzyme‐mimicking and ultrasound‐responsive Nb2C‐Pt@HA‐PEG nanozyme. ROS‐eliminating and anti­inflammatory capability of Nb2C‐Pt@HA‐PEG under US irradiation are demonstrated on macrophages and endothelial cells in vitro. Nb2C‐Pt@HA‐PEG‐mediated sonocatalytic therapy exerts an outstanding anti‐atherosclerosis efficacy by ...
Qianqian Bai, Xinyue Lao, Sin‐Yi Pang, Yifei Zhao, Yuan Liu, Xiao Yu Tian, Jianhua Hao   +6 more
wiley   +1 more source

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

, 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

Spin foam models and the classical action principle [PDF]

Advances in Theoretical and Mathematical Physics, 1998
We propose a new systematic approach that allows one to derive the spin foam (state sum) model of a theory starting from the corresponding classical action functional. It can be applied to any theory whose action can be written as that of the BF theory plus a functional of the B field.
Laurent Freidel, Kirill Krasnov
openaire   +3 more sources

High‐Energy‐Density Aqueous Zinc‐Ion Batteries: Recent Progress, Design Strategies, Challenges, and Perspectives

Advanced Materials, EarlyView.
Strategies achieving high‐energy‐density aqueous zinc‐ion batteries are summarized and analyzed from both their separate advancements and the integrated effectiveness in this review. Then, perspectives are given for valuable guidance for further development of high‐energy‐density aqueous zinc‐ion batteries.
Mingcong Tang, Qun Liu, Xiaohong Zou, Biao Zhang, Liang An   +4 more
wiley   +1 more source

Finiteness and Dual Variables for Lorentzian Spin Foam Models

, 2005
We describe here some new results concerning the Lorentzian Barrett-Crane model, a well-known spin foam formulation of quantum gravity. Generalizing an existing finiteness result, we provide a concise proof of finiteness of the partition function ...
Apostol T M, Ashtekar A, Baez J C, Baez J C, Baez J C, Baez J C, Barrett J W, Barrett J W, Barrett J W, Barrett J W, Barrett J W, Bojowald M Perez A, Borwein J, Cherrington J W, Cherrington J W Christensen J D, Christensen J D, Christensen J D, Crane L Perez A Rovelli C, Freidel L, J Wade Cherrington, Makela J, Makela J, Perez A, Pfeiffer H, Wainwright C   +24 more
core   +1 more source