Unexpected remarkable stability of primary ozonides derived from alkenyl stannanes. One-pot synthesis of 1,2-diols from alkynes

Primary ozonides derived from alkenyl stannanes display an unusual stability and can be transformed into 1,2-diols by treatment with dimethyl sulfide and borane-methyl sulfide complex. This observation has been incorporated into the development of a novel one-pot strategy for the conversion of alkynes into 1,2-diols.     

Population dynamics of a two‐stage species with recruitment

This work models and analyzes the qualitative dynamics of a two‐stage species with the factor of recruitment. It shows how the dynamics is determined by a basic threshold parameter . As a result, it is proved that if , then the extinction equilibrium point is globally asymptotically stable, assuring that the species would disappear under this condition. Numerical simulations, produced by varying the parameters obtained from empirical data, show different situations regarding the evolution of the population and allow us to validate the model. Copyright © 2012 John Wiley & Sons, Ltd.     

Parallel discrete dynamical systems on independent local functions

In this paper, we extend the manner of defining the evolution update of discrete dynamical systems on Boolean functions, without limiting the local functions to being dependent restrictions of a global one. Then, we analyze the cases concerned with parallel dynamical systems with the OR$OR$, AND$AND$, NAND$NAND$ and NOR$NOR$ functions as independent local functions over undirected and also directed dependency graphs. This extension of the update method widely generalizes the traditional one where only a global Boolean function is considered for establishing the evolution operator of the system. Besides, our analysis allows us to show a richer dynamics in these new kinds of parallel dynamical systems.     

Quantum communication via controlled holes in the statistical distribution of excitations in a nanoresonator coupled to a Cooper pair box

We propose a scheme to transmit information via the statistical distribution of excitations of a nanomechanical resonator. It employs a controllable coupling between this system and a Cooper pair box. The success probability and the fidelity are calculated and compared with those obtained in an atom-field system in different regimes. Addtionaly, the scheme can also be applied to prepare low excited Fock states.     

On the structure of F-indistinguishability operators

Some properties concerning the structure of F-indistinguishability operators are analyzed. It is shown that any of such operators is generated by a family of fuzzy subsets. This result, since it gives the way to construct F-indistinguishabilities, facilitates new applications of fuzzy relations. The links between F-indistinguishability operators and a kind of generalized metrics in the unit interval - which are also explored - are used to define the canonical generators of an F-indistinguishability operator, that is, the fuzzy partition associated with the operator.     

Topological efficiency in three-dimensional gallery networks of termite nests

Transport networks are a key component of human and natural societies that enable efficient communication at a low cost. Here, we study the topological efficiency of the three-dimensional networks of galleries in termite nests and how spatial constraints affect the organisation of these networks. Cubitermes termite nests have far better than random transportation efficiency, but they do not reach theoretical optimal performance. We rather suggest a multiobjective process where a number of additional requirements, such as resilience to external attacks and the presence of spatial constraints, limit the ability of the system to achieve maximal transportation performance.     

One-pot synthesis of 1-exo-alkylidene-2,3-anhydro furanoses: convenient precursors for exo-glycals and functionalized C-glycals

1-exo-Methylene-2,3-anhydro furanoses, obtained from C-glycals in a one-pot, three step operation can be readily transformed into functionalized C-glycals by palladium-catalyzed nucleophilic addition.     

On folded coverings of quasi-manifolds with boundary

LetM andN be quasi-manifolds possibly with boundary, we call afolded-covering p: N→M to a non-degenerate simplicial map, such thatp: N/p ^?1(?M)→M/?M is a branched covering. The purpose of this paper will be to classify the folded coverings of a given quasi-manifold by using the representations of a particular group on permutation groups, similar to the monodromy representations for coverings and in such a way that includes these ones a particular case. We shall apply our result to the theory of orbifolds to obtain a presentation (alternative to the one in [H-Q]) of the fundamental group for an orbifold defined on a quasi-manifold.     

Efficiency and robustness in ant networks of galleries

Recent theoretical and empirical studies have focused on the topology of large networks of communication/interactions in biological, social and technological systems. Most of them have been studied in the scope of the small-world and scale-free networks theory. Here we analyze the characteristics of ant networks of galleries produced in a 2-D experimental setup. These networks are neither small-worlds nor scale-free networks and belong to a particular class of network, i.e. embedded planar graphs emerging from a distributed growth mechanism. We compare the networks of galleries with both minimal spanning trees and greedy triangulations. We show that the networks of galleries have a path system efficiency and robustness to disconnections closer to the one observed in triangulated networks though their cost is closer to the one of a tree. These networks may have been prevented to evolve toward the classes of small-world and scale-free networks because of the strong spatial constraints under which they grow, but they may share with many real networks a similar trend to result from a balance of constraints leading them to achieve both path system efficiency and robustness at low cost.Received: 16 July 2004, Published online: 26 November 2004PACS: 89.75.Fb Structures and organization in complex systems - 89.75.Hc Networks and genealogical trees - 87.23.Ge Dynamics of social systems     

Electromagnetic field at finite temperature: A first order approach

In this work we study the electromagnetic field at finite temperature via the massless DKP formalism. The constraint analysis is performed and the partition function for the theory is constructed and computed. When it is specialized to the spin 1 sector we obtain the well-known result for the thermodynamic equilibrium of the electromagnetic field.