4,456 research outputs found
Asymmetric trehalose analogues to probe disaccharide processing pathways in mycobacteria
The uptake and metabolism of the disaccharide trehalose by Mycobacterium tuberculosis is essential for the virulence of this pathogen. Here we describe the chemoenzymatic synthesis of new azido-functionalised asymmetric trehalose probes that resist degradation by mycobacterial enzymes and are used to probe trehalose processing pathways in mycobacteria
Topological color codes on Union Jack lattices: A stable implementation of the whole Clifford group
We study the error threshold of topological color codes on Union Jack
lattices that allow for the full implementation of the whole Clifford group of
quantum gates. After mapping the error-correction process onto a statistical
mechanical random 3-body Ising model on a Union Jack lattice, we compute its
phase diagram in the temperature-disorder plane using Monte Carlo simulations.
Surprisingly, topological color codes on Union Jack lattices have similar error
stability than color codes on triangular lattices, as well as the Kitaev toric
code. The enhanced computational capabilities of the topological color codes on
Union Jack lattices with respect to triangular lattices and the toric code
demonstrate the inherent robustness of this implementation.Comment: 8 pages, 4 figures, 1 tabl
Spin dynamics in rare earth single molecule magnets from muSR and NMR in [TbPc] and [DyPc]
The spin dynamics in [TbPc] and [DyPc] single
molecule magnets have been investigated by means of muon and nuclear
spin-lattice relaxation rate measurements. The correlation time for the spin
fluctuations was found to be close to 0.1 ms already at 50 K, about two orders
of magnitude larger than the one previously found in other lanthanide based
single molecule magnets. In [TbPc] two different regimes for the
spin fluctuations have been evidenced: a high temperature activated one
involving spin fluctuations across a barrier separating
the ground and first excited states and a low temperature regime involving
quantum fluctuations within the twofold degenerate ground-state. In
[DyPc] a high temperature activated spin dynamics is also evidenced
which, however, cannot be explained in terms of a single spin-phonon coupling
constant.Comment: 4 pages, 4 figure
Spin and charge dynamics in [TbPc] and [DyPc] single molecule magnets
Magnetization, AC susceptibility and SR measurements have been performed
in neutral phthalocyaninato lanthanide ([LnPc) single molecule magnets
in order to determine the low-energy levels structure and to compare the
low-frequency spin excitations probed by means of macroscopic techniques, such
as AC susceptibility, with the ones explored by means of techniques of
microscopic character, such as SR. Both techniques show a high temperature
thermally activated regime for the spin dynamics and a low temperature
tunneling one. While in the activated regime the correlation times for the spin
fluctuations estimated by AC susceptibility and SR basically agree, clear
discrepancies are found in the tunneling regime. In particular, SR probes
a faster dynamics with respect to AC susceptibility. It is argued that the
tunneling dynamics probed by SR involves fluctuations which do not yield a
net change in the macroscopic magnetization probed by AC susceptibiliy. Finally
resistivity measurements in [TbPc crystals show a high temperature
nearly metallic behaviour and a low temperature activated behaviour.Comment: 8 pages, 12 figure
Microsatellite markers in Spanish lime (Melicoccus bijugatus Jacq., Sapindaceae), a neglected Neotropical fruit crop
Spanish lime (Melicoccus bijugatus Jacq.) is aNeotropical fruit tree cultivated, mainly, in orchards for self-consumption or local sale. The genus Melicoccus includes other nine species with edible fruits, some of these species are at risk of extinction. Like for the vast majority of tropical fruit trees, there is no information on the genetic diversity of Spanish lime and its related species, and this is mostly due to the lack of molecular markers. The objectives of this study were to present the first microsatellite markers developed for Spanish lime, testing its usefulness on a sample of cultivated accessions, as well as its transferability to Huaya India (M. oliviformis). To do this, we performed high-throughput sequencing of microsatellite-enriched libraries of Spanish lime using Roche 454, assembled 9567 DNA contig sequences and identified 10,117 microsatellites. After screening 384 of those microsatellites on four DNA samples, 31 polymorphic markers were used to screen 25 accessions of Spanish lime and five of Huaya India collected in Yucatan, Mexico. Genetic diversity was low in Spanish lime (A = 20.61, HE = 0.38) and similar for both sexes of this species. Neighbor-Joining and PCoA analyses clearly discriminated between the two Melicoccus species studied. Nine of the markers showed unique alleles for Huaya India. The set of microsatellite markers developed has a great potential to generate information in relation to conservation genetics, improvement of elite cultivars and breeding programs for Spanish lime and related species
Going concern opinions are not bad news : evidence from industry rivals
This paper examines whether going concern audit opinions (GCO) affect the stock price performance of the announcing firms and their industry rivals. Our original evidence
clearly suggests that such accounting event is asymmetrically perceived by the market depending on whether the firm is qualified by the auditor or not. In particular, firms receiving a GCO earn negative abnormal returns at the audit report’s disclosure date and over the following year whereas their industry rivals exhibit positive abnormal returns at the GCO date and in the
subsequent one-month period. This is in contrast with the preevent abnormal returns, which, on average, are negative and significant for all firms operating within the industry. Overall, we highlight the relevance of audit opinions and mandatory accounting information for the timing of
transactions in financial markets
Microscopic mechanism for mechanical polishing of diamond (110) surfaces
Mechanically induced degradation of diamond, as occurs during polishing, is
studied using total--energy pseudopotential calculations. The strong asymmetry
in the rate of polishing between different directions on the diamond (110)
surface is explained in terms of an atomistic mechanism for nano--groove
formation. The post--polishing surface morphology and the nature of the
polishing residue predicted by this mechanism are consistent with experimental
evidence.Comment: 4 pages, 5 figure
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