352 research outputs found
Constitutive and Inducible Expression of the rRNA Methylase Gene erm(B) in Campylobacter
Macrolides are the antimicrobials of choice for treating human campylobacteriosis. The recent emergence of erm(B) in Campylobacter bacteria threatens the utility of this class of antibiotics. Here we report the constitutive and inducible expression of erm(B) in Campylobacter isolates derived from diarrheal patients and food-producing animals. Constitutive expression of erm(B) was associated with insertion and deletion in the regulatory region of the gene, providing the first documentation of the differential expression of erm(B) in Campylobacter bacteria
A Unitary Weights Based One-Iteration Quantum Perceptron Algorithm for Non-Ideal Training Sets
In order to solve the problem of non-ideal training sets (i.e., the
less-complete or over-complete sets) and implement one-iteration learning, a
novel efficient quantum perceptron algorithm based on unitary weights is
proposed, where the singular value decomposition of the total weight matrix
from the training set is calculated to make the weight matrix to be unitary.
The example validation of quantum gates {H, S, T, CNOT, Toffoli, Fredkin} shows
that our algorithm can accurately implement arbitrary quantum gates within one
iteration. The performance comparison between our algorithm and other quantum
perceptron algorithms demonstrates the advantages of our algorithm in terms of
applicability, accuracy, and availability. For further validating the
applicability of our algorithm, a quantum composite gate which consists of
several basic quantum gates is also illustrated.Comment: 12 pages, 5 figure
A Novel Quantum Visual Secret Sharing Scheme
Inspired by Naor et al.'s visual secret sharing (VSS) scheme, a novel n out
of n quantum visual secret sharing (QVSS) scheme is proposed, which consists of
two phases: sharing process and recovering process. In the first process, the
color information of each pixel from the original secret image is encoded into
an n-qubit superposition state by using the strategy of quantum expansion
instead of classical pixel expansion, and then these n qubits are distributed
as shares to n participants, respectively. During the recovering process, all
participants cooperate to collect these n shares of each pixel together, then
perform the corresponding measurement on them, and execute the n-qubit XOR
operation to recover each pixel of the secret image. The proposed scheme has
the advantage of single-pixel parallel processing that is not available in the
existing analogous quantum schemes and perfectly solves the problem that in the
classic VSS schemes the recovered image has the loss in resolution. Moreover,
its experiment implementation with the IBM Q is conducted to demonstrate the
practical feasibility.Comment: 19 pages, 13 figure
Emergence of Multidrug-Resistant Campylobacter Species Isolates with a Horizontally Acquired rRNA Methylase
Antibiotic-resistant Campylobacter constitutes a serious threat to public health, and resistance to macrolides is of particular concern, as this class of antibiotics is the drug of choice for clinical therapy of campylobacteriosis. Very recently, a horizontally transferrable macrolide resistance mediated by the rRNA methylase gene erm(B) was reported in a Campylobacter coli isolate, but little is known about the dissemination of erm(B) among Campylobacter isolates and the association of erm(B)-carrying isolates with clinical disease. To address this question and facilitate the control of antibiotic-resistant Campylobacter, we determined the distribution of erm(B) in 1,554 C. coli and Campylobacter jejuni isolates derived from food-producing animals and clinically confirmed human diarrheal cases. The results revealed that 58 of the examined isolates harbored erm(B) and exhibited high-level resistance to macrolides, and most were recent isolates, derived in 2011-2012. In addition, the erm(B)-positive isolates were all resistant to fluoroquinolones, another clinically important antibiotic used for treating campylobacteriosis. The erm(B) gene is found to be associated with chromosomal multidrug resistance genomic islands (MDRGIs) of Gram-positive origin or with plasmids of various sizes. All MDRGIs were transferrable to macrolide-susceptible C. jejuni by natural transformation under laboratory conditions. Molecular typing of the erm(B)-carrying isolates by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) identified diverse genotypes and outbreak-associated diarrheal isolates. Molecular typing also suggested zoonotic transmission of erm(B)-positive Campylobacter. These findings reveal an emerging and alarming trend of dissemination of erm(B) and MDRGIs in Campylobacter and underscore the need for heightened efforts to control their further spread
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