scholarly journals A note on stable complex structures on real vector bundles over manifolds

2015 ◽  
Vol 189 ◽  
pp. 1-9 ◽  
Author(s):  
Huijun Yang
1991 ◽  
Vol 06 (08) ◽  
pp. 1319-1333 ◽  
Author(s):  
MARK J. BOWICK ◽  
KONG-QING YANG

The equations of motion for the massless modes of the closed bosonic string are obtained in the adiabatic approximation from the requirement of the vanishing of the curvature of appropriate vector bundles over the space of complex structures Diff S1/S1. This vanishing is required for physical states to be independent of string parametrization.


1998 ◽  
Vol 95 (1) ◽  
pp. 323-330 ◽  
Author(s):  
Martin Čadek ◽  
Jiří Vanžura

2017 ◽  
Author(s):  
Carlos G. Oliver ◽  
Vladimir Reinharz ◽  
Jérôme Waldispühl

AbstractThe RNA world hypothesis relies on the ability of ribonucleic acids to spontaneously acquire complex structures capable of supporting essential biological functions. Multiple sophisticated evolutionary models have been proposed for their emergence, but they often assume specific conditions. In this work we explore a simple and parsimonious scenario describing the emergence of complex molecular structures at the early stages of life. We show that at specific GC-content regimes, an undirected replication model is sufficient to explain the apparition of multi-branched RNA secondary structures – a structural signature of many essential ribozymes. We ran a large scale computational study to map energetically stable structures on complete mutational networks of 50-nucleotide-long RNA sequences. Our results reveal that the sequence landscape with stable structures is enriched with multi-branched structures at a length scale coinciding with the appearance of complex structures in RNA databases. A random replication mechanism preserving a 50% GC-content may suffice to explain a natural enrichment of stable complex structures in populations of functional RNAs. By contrast, an evolutionary mechanism eliciting the most stable folds at each generation appears to help reaching multi-branched structures at highest GC content.


Author(s):  
Jacques Allard

We say that a real vector bundle ξ over a finite C.W. complex X is stably trivial of type (n, k) or, simply, of type (n, k) if ξ ⊕ kε ≅ nε, where ε denotes a trivial line bundle. The following theorem is an immediate corollary (see (12)) of a theorem of T. Y. Lam ((9), theorem 2).


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