Fast, high fidelity information transmission through spin chain quantum wires

Spin chains have been proposed as quantum wires for information transfer in solid state quantum architectures. We show that huge gains in both transfer speed and fidelity are possible using a minimalist control approach that relies only a single, local, on-off switch actuator. Effective switching time sequences can be determined using optimization techniques for both ideal and disordered chains. Simulations suggest that effective optimization is possible even in the absence of accurate models.Comment: revtex4, 4 pages, 5 figure

Perfect Quantum Routing in Regular Spin Networks

Regular families of coupled quantum networks are described such the unknown state of a qubit can be perfectly routed from any node to any other node in a time linear in the distance. Unlike previous constructions, the transfer can be achieved perfectly on a network that is local on any specified number of spatial dimensions. The ability to route the state, and the regularity of the networks, vastly improve the utility of this scheme in comparison to perfect state transfer schemes. The structures can also be used for entanglement generation.Comment: 4 pages, 3 figure

Carbocations and the Complex Flavor and Bouquet of Wine: Mechanistic Aspects of Terpene Biosynthesis in Wine Grapes.

Computational chemistry approaches for studying the formation of terpenes/terpenoids in wines are presented, using five particular terpenes/terpenoids (1,8-cineole, α-ylangene, botrydial, rotundone, and the wine lactone), volatile compounds (or their precursors) found in wine and/or wine grapes, as representative examples. Through these examples, we show how modern computational quantum chemistry can be employed as an effective tool for assessing the validity of proposed mechanisms for terpene/terpenoid formation

Modulation of inherent dynamical tendencies of the bisabolyl cation via preorganization in epi-isozizaene synthase.

The relative importance of preorganization, selective transition state stabilization and inherent reactivity are assessed through quantum chemical and docking calculations for a sesquiterpene synthase (epi-isozizaene synthase, EIZS). Inherent reactivity of the bisabolyl cation, both static and dynamic, appears to determine the pathway to product, although preorganization and selective binding of the final transition state structure in the multi-step carbocation cascade that forms epi-isozizaene appear to play important roles

Identification and comparative analysis of sixteen fungal peptidyl-prolyl cis/trans isomerase repertoires

BACKGROUND: The peptidyl-prolyl cis/trans isomerase (PPIase) class of proteins is present in all known eukaryotes, prokaryotes, and archaea, and it is comprised of three member families that share the ability to catalyze the cis/trans isomerisation of a prolyl bond. Some fungi have been used as model systems to investigate the role of PPIases within the cell, however how representative these repertoires are of other fungi or humans has not been fully investigated. RESULTS: PPIase numbers within these fungal repertoires appears associated with genome size and orthology between repertoires was found to be low. Phylogenetic analysis showed the single-domain FKBPs to evolve prior to the multi-domain FKBPs, whereas the multi-domain cyclophilins appear to evolve throughout cyclophilin evolution. A comparison of their known functions has identified, besides a common role within protein folding, multiple roles for the cyclophilins within pre-mRNA splicing and cellular signalling, and within transcription and cell cycle regulation for the parvulins. However, no such commonality was found with the FKBPs. Twelve of the 17 human cyclophilins and both human parvulins, but only one of the 13 human FKBPs, identified orthologues within these fungi. hPar14 orthologues were restricted to the Pezizomycotina fungi, and R. oryzae is unique in the known fungi in possessing an hCyp33 orthologue and a TPR-containing FKBP. The repertoires of Cryptococcus neoformans, Aspergillus fumigatus, and Aspergillus nidulans were found to exhibit the highest orthology to the human repertoire, and Saccharomyces cerevisiae one of the lowest. CONCLUSION: Given this data, we would hypothesize that: (i) the evolution of the fungal PPIases is driven, at least in part, by the size of the proteome, (ii) evolutionary pressures differ both between the different PPIase families and the different fungi, and (iii) whilst the cyclophilins and parvulins have evolved to perform conserved functions, the FKBPs have evolved to perform more variable roles. Also, the repertoire of Cryptococcus neoformans may represent a better model fungal system within which to study the functions of the PPIases as its genome size and genetic tractability are equal to those of Saccharomyces cerevisiae, whilst its repertoires exhibits greater orthology to that of humans. However, further experimental investigations are required to confirm this