Search results for " cloning"
showing 10 items of 82 documents
Cloning transformations in spin networks without external control
2004
In this paper we present an approach to quantum cloning with unmodulated spin networks. The cloner is realized by a proper design of the network and a choice of the coupling between the qubits. We show that in the case of phase covariant cloner the XY coupling gives the best results. In the 1->2 cloning we find that the value for the fidelity of the optimal cloner is achieved, and values comparable to the optimal ones in the general N->M case can be attained. If a suitable set of network symmetries are satisfied, the output fidelity of the clones does not depend on the specific choice of the graph. We show that spin network cloning is robust against the presence of static imperfection…
Effects of noise on spin network cloning
2006
We analyze the effects of noise on quantum cloning based on the spin network approach. A noisy environment interacting with the spin network is modeled both in a classical scenario, with a classical fluctuating field, and in a fully quantum scenario, in which the spins are coupled with a bath of harmonic oscillators. We compare the realization of cloning with spin networks and with traditional quantum gates in the presence of noise, and show that spin network cloning is more robust.
Quantum cloning in spin networks
2004
We introduce an approach to quantum cloning based on spin networks and we demonstrate that phase covariant cloning can be realized using no external control but only with a proper design of the Hamiltonian of the system. In the 1 -> 2 cloning we find that the XY model saturates the value for the fidelity of the optimal cloner and gives values comparable to it in the genera N -> M case. We finally discuss the effect of external noise. Our protocol is much more robust to decoherence than a conventional procedure based on quantum gates.
Information-flux approach to multiple-spin dynamics
2007
We introduce and formalize the concept of information flux in a many-body register as the influence that the dynamics of a specific element receive from any other element of the register. By quantifying the information flux in a protocol, we can design the most appropriate initial state of the system and, noticeably, the distribution of coupling strengths among the parts of the register itself. The intuitive nature of this tool and its flexibility, which allow for easily manageable numerical approaches when analytic expressions are not straightforward, are greatly useful in interacting many-body systems such as quantum spin chains. We illustrate the use of this concept in quantum cloning an…
Detection of a Single Gene Encoding Glutamine Synthetase in Sinapis alba (L.)
1991
Summary Ion-exchange chromatography of glutamine synthetase polypeptides (GS; EC 6.3.1.2) from green leaves and the roots of Sinapis alba yielded identical elution patterns. This is likewise true for GS from etiolated cotyledons. As we have previously demonstrated the identity of GS-enzymes from etiolated and green leaf tissues, the obviously very similar charge properties of GS-proteins indicate the eventual existence of only one type of GS in all mustard plant organs. To further prove this possibility, Southern blot analysis of mustard DNA was carried out using hybridization probes specific to different GS-isoforms. Concluding from the relative strength of the hybridization signals, the G…
A multi-centre study of candidate genes for wheeze and allergy: the International Study of Asthma and Allergies in Childhood Phase 2
2009
BACKGROUND: Common polymorphisms have been identified in genes suspected to play a role in asthma. We investigated their associations with wheeze and allergy in a case-control sample from Phase 2 of the International Study of Asthma and Allergies in Childhood. METHODS: We compared 1105 wheezing and 3137 non-wheezing children aged 8-12 years from 17 study centres in 13 countries. Genotyping of 55 candidate single nucleotide polymorphisms (SNPs) in 14 genes was performed using the Sequenom System. Logistic regression models were fitted separately for each centre and each SNP. A combined per allele odds ratio and measures of heterogeneity between centres were derived by random effects meta-ana…
Molecular cloning and evolution of lobster hemocyanin.
2001
In the American lobster, Homarus americanus, oxygen is transported by a hemocyanin that is composed 2 x 6 subunits. N-terminal sequencing show the presence of three distinct subunit types (alpha, beta and gamma). We cloned the cDNA of one of these subunits that belong to the alpha-type. It encodes a hemocyanin subunit of 654 amino acids with a molecular mass of 84.8 kDa, which is synthesized in the hepatopancreas. Phylogenetic analyses of the crustacean hemocyanin sequences show two well-separated clades, which correspond to the alpha and gamma-type subunits. Sequences of beta-type subunits are still unknown. The gamma-sequences have evolved about 15% faster than the alpha-subunits, consist…
Unequal distribution of RT-PCR artifacts along the E1-E2 region of Hepatitis C virus.
2009
Although viral variability studies have focused traditionally on consensus sequences, the relevance of molecular clone sequences for studying viral evolution at the intra-host level is being increasingly recognized. However, for this approach to be reliable, RT-PCR artifacts do not have to contribute excessively to the observed variability. Molecular clone sequences were obtained from an in vitro transcript to estimate the maximum error rate associated to RT-PCR for the Hepatitis C virus (HCV) E1-E2 region. On average, the frequency of RT-PCR errors was one order of magnitude lower than the level of intra-host genetic variability observed in samples from an HCV outbreak. However, RT-PCR err…
Molecular cloning and functional bacterial expression of a plant glucosidase specifically involved in alkaloid biosynthesis.
2000
Monoterpenoid indole alkaloids are a vast and structurally complex group of plant secondary compounds. In contrast to other groups of plant products which produce many glycosides, indole alkaloids rarely occur as glucosides. Plants of Rauvolfia serpentina accumulate ajmaline as a major alkaloid, whereas cell suspension cultures of Rauvolfia mainly accumulate the glucoalkaloid raucaffricine at levels of 1.6 g/l. Cell cultures do contain a specific glucosidase. known as raucaffricine-O-beta-D-glucosidase (RG), which catalyzes the in vitro formation of vomilenine, a direct intermediate in ajmaline biosynthesis. Here, we describe the molecular cloning and functional expression of this enzyme in…