11 research outputs found
Emergent phenomena in Nature: a paradox with Theory?
The existence of various physical phenomena stems from the concept called
asymptotic emergence, that is, they seem to be exclusively reserved for certain
limiting theories. Important examples are spontaneous symmetry breaking (SSB)
and phase transitions: these would only occur in the classical or thermodynamic
limit of underlying finite quantum systems, since for finite quantum systems,
due to the uniqueness of the relevant states, such phenomena are excluded by
Theory. In Nature, however, finite quantum systems describing real materials
clearly exhibit such effects. In this paper we discuss these apparently
``paradoxical'' phenomena and outline various ideas and mechanisms that
encompass both theory and reality, from physical and mathematical points of
view.Comment: 21 pages, 5 figure
DLR-KMS correspondence on lattice spin systems
The Dobrushin-Lanford-Ruelle (DLR) condition and the classical
Kubo-Martin-Schwinger (KMS) condition are considered in the context of
classical lattice systems. In particular, we prove that these conditions are
equivalent for the case of a lattice spin system with values in a compact
symplectic manifold by showing that infinite volume Gibbs states are in
bijection with KMS states.Comment: 13 page
Colorectal liver metastases: Surgery versus thermal ablation (COLLISION) - a phase III single-blind prospective randomized controlled trial
Background: Radiofrequency ablation (RFA) and microwave ablation (MWA) are widely accepted techniques to eliminate small unresectable colorectal liver metastases (CRLM). Although previous studies labelled thermal ablation inferior to surgical resection, the apparent selection bias when comparing patients with unresectable disease to surgical candidates, the superior safety profile, and the competitive overall survival results for the more recent reports mandate the setup of a randomized controlled trial. The objective of the COLLISION trial is to prove non-inferiority of thermal ablation compared to hepatic resection in patients with at least one resectable and ablatable CRLM and no extrahepatic disease. Methods: In this two-arm, single-blind multi-center phase-III clinical trial, six hundred and eighteen patients with at least one CRLM (≤3cm) will be included to undergo either surgical resection or thermal ablation of appointed target lesion(s) (≤3cm). Primary endpoint is OS (overall survival, intention-to-treat analysis). Main secondary endpoints are overall disease-free survival (DFS), time to progression (TTP), time to local progression (TTLP), primary and assisted technique efficacy (PTE, ATE), procedural morbidity and mortality, length of hospital stay, assessment of pain and quality of life (QoL), cost-effectiveness ratio (ICER) and quality-adjusted life years (QALY). Discussion: If thermal ablation proves to be non-inferior in treating lesions ≤3cm, a switch in treatment-method may lead to a reduction of the post-procedural morbidity and mortality, length of hospital stay and incremental costs without compromising oncological outcome for patients with CRLM. Trial registration:NCT03088150 , January 11th 2017
The classical limit and spontaneous symmetry breaking in algebraic quantum theory
In this paper an overview of some recent developments on the classical limit
and spontaneous symmetry breaking (SSB) in algebraic quantum theory is given.
In such works, based on the theory of -algebras, the concept of the
classical limit has been formalized in a complete algebraic manner.
Additionally, since this setting allows for commutative as well as
non-commutative -algebras, and hence for classical and quantum theories,
it provides an excellent framework to study SBB as an emergent phenomenon when
transitioning from the quantum to the classical world by turning off a
semi-classical parameter. We summarize the main results and show that this
algebraic approach sheds new light on the connection between the classical and
the quantum realm, where particular emphasis is placed on the role of SSB in
Theory versus Nature. To this end a detailed analysis is carried out and
illustrated with three different physical models: Schr\"{o}dinger operators,
mean-field quantum spin systems and the Bose-Hubbard model.Comment: 30 page