Enhancement Of Fidelity Research Articles

Bidirectional multi-qubit quantum teleportation in noisy channel aided with weak measurement**Project supported by the National Natural Science Foundation of China (Grant No. 61172071), the Scientific Research Program Funded by Shaanxi Provincial Education Department, China (Grant No. 16JK1711), the International Scientific Cooperation Program of Shaanxi Province, China (Grant No. 2015KW-013), and the Natural Science Foundation Research Project of Shaanxi Province, China

Recently, bidirectional quantum teleportation has attracted a great deal of research attention. However, existing bidirectional teleportation schemes are normally discussed on the basis of perfect quantum environments. In this paper, we first put forward a bidirectional teleportation scheme to transport three-qubit Greenberger–Horne–Zeilinger (GHZ) states based on controled-not (CNOT) operation and single-qubit measurement. Then, we generalize it to the teleportation of multi-qubit GHZ states. Further, we discuss the influence of quantum noise on our scheme by the example of an amplitude damping channel, then we obtain the fidelity of the teleportation. Finally, we utilize the weak measurement and the corresponding reversing measurement to protect the quantum entanglement, which shows an effective enhancement of the teleportation fidelity.

Noisy quantum teleportation: An experimental study on the influence of local environments

We report experimental results on the action of selected local environments on the fidelity of the quantum teleportation protocol, taking into account non-ideal, realistic entangled resources. Different working conditions are theoretically identified, where a noisy protocol can be made almost insensitive to further addition of noise. We put to test these conditions on a photonic implementation of the quantum teleportation algorithm, where two polarization entangled qubits act as the entangled resource and a path qubit on Alice encodes the state to be teleported. Bob's path qubit is used to implement a local environment, while the environment on Alice's qubit is simulated as a weighed average of different pure states. We obtain a good agreement with the theoretical predictions, we experimentally recreate the conditions to obtain a noise-induced enhancement of the protocol fidelity, and we identify parameter regions of increased insensibility to interactions with specific noisy environments.

Enhancing teleportation fidelity by means of weak measurements or reversal

The enhancement of teleportation fidelity by weak measurement or quantum measurement reversal is investigated. One qubit of a maximally entangled state undergoes the amplitude damping, and the subsequent application of weak measurement or quantum measurement reversal could improve the teleportation fidelity beyond the classical region. The improvement could not be attributed to the increasing of entanglement, quantum discord, classical correlation or total correlation. We declare that it should be owed to the probabilistic nature of the method.

Improving quantum state transfer in a general XY chain via the Dzyaloshinsky—Moriya interaction

We study the state transfer of Bell states in a general XY spin chain using the Dzyaloshinsky—Moriya interaction. Two symmetries of fidelity with the anisotropy parameter are found. The maximum fidelity is shown to be significantly enhanced in cases of an odd number of sites. Enhancement of fidelity on a singlet state is greater than that on the other Bell states in such cases.

The assessment, monitoring, and enhancement of treatment fidelity in public health clinical trials

OBJECTIVES: To discuss methods of preservation of treatment fidelity in health behavior change trials conducted in public health contexts. METHODS: The treatment fidelity framework provided by the NIH's Behavioral Change Consortium (BCC) (1) includes five domains of treatment fidelity (Study Design, Training, Delivery, Receipt, and Enactment). A measure of treatment fidelity was previously developed and validated using these categories. RESULTS: Strategies for assessment, monitoring, and enhancing treatment fidelity within each of the five treatment fidelity domains are discussed. The previously created measure of treatment fidelity is updated to include additional items on selecting providers, additional confounders, theory testing, and multicultural considerations. CONCLUSIONS: Implementation of a treatment fidelity plan may require extra staff time and costs. However, the economic and scientific costs of lack of attention to treatment fidelity are far greater than the costs of treatment fidelity implementation. Maintaining high levels of treatment fidelity with flexible adaptation according to setting, provider, and patient is the goal for public health trials.

Visual Deprivation Suppresses L5 Pyramidal Neuron Excitability by Preventing the Induction of Intrinsic Plasticity

In visual cortex monocular deprivation (MD) during a critical period (CP) reduces the ability of the deprived eye to activate cortex, but the underlying cellular plasticity mechanisms are incompletely understood. Here we show that MD reduces the intrinsic excitability of layer 5 (L5) pyramidal neurons and enhances long-term potentiation of intrinsic excitability (LTP-IE). Further, MD and LTP-IE induce reciprocal changes in K(v)2.1 current, and LTP-IE reverses the effects of MD on intrinsic excitability. Taken together these data suggest that MD reduces intrinsic excitability by preventing sensory-drive induced LTP-IE. The effects of MD on excitability were correlated with the classical visual system CP, and (like the functional effects of MD) could be rapidly reversed when vision was restored. These data establish LTP-IE as a candidate mechanism mediating loss of visual responsiveness within L5, and suggest that intrinsic plasticity plays an important role in experience-dependent refinement of visual cortical circuits.

Effects of molding conditions on transcription molding of microscale prism patterns using ultra‐high‐speed injection molding

AbstractIn this study, we performed a series of molding tests to investigate the potential of microscale transcription of polymer by ultra‐high‐speed injection molding (UHSIM). During the tests, the injection speed was varied up to a maximum of 995 mm/s. Polymethyl methacrylate was molded under various injection molding conditions, including cavity vacuum pumping process, so as to replicate an electroformed nickel stamper exhibiting V‐grooves with a pitch of 50 μm. Surface configurations of molded samples were observed and measured using a laser scanning microscope. The transcription ratio (TR) is defined as the ratio of the depths of V‐grooves in both the molded samples and the stamper. An excellent average TR of 0.97 was performed when molding at an injection rate of 800 cm3/s (injection speed of 995 mm/s), mold temperature of 80°C, and holding pressure of 120 MPa. In addition, the effect of vacuum on transcription molding was investigated in detail; the result proved that vacuum is an important factor in the enhancement of transcription fidelity. The strong influence of injection rate on the TR indicates the applicability of UHSIM to the field of transcription molding of polymers. POLYM. ENG. SCI. 46:1140–1146, 2006. © 2006 Society of Plastics Engineers.

Diagnosis of biological tissue morphology and function with endoscopic optical coherence tomography.

We present some of the recent technological advances in our MEMS-based endoscopic optical coherence tomography (OCT) system for the enhancement of image fidelity and diagnosis. The endoscopic OCT system permits simultaneous cross-sectional OCT imaging and en face white-light visual guidance as well as fluorescence imaging guidance. The transverse and axial resolutions of the OCT scope are roughly 12μm and 10μm, respectively, and the axial resolution can be enhanced to 3um if connecting it to our recent custom sub-8fs Ti:Al2O3laser. To test the endoscopic OCT system for imaging diagnosis of early epithelial cancers, rat bladder cancer models were used and the results show over 90% sensitivity and specificity. Applications in imaging of bladder functions and engineering tissue growth are demonstrated.

Enhancement of DNA, cDNA synthesis and fidelity at high temperatures by a dimeric single-stranded DNA-binding protein.

Bacterial single-stranded DNA-binding proteins (SSBs) are required for DNA replication and repair. We have over-expressed and purified the native form and two His-tagged fusions of the SSB from Thermus thermophilus (TthSSB). The three proteins were found as dimers in solution. They bound in vitro to single-stranded DNA specifically over a temperature range of 4-80 degrees C, and the wild-type protein could withstand incubation at 94 degrees C for 2 min. Addition of TthSSB to PCR halved the elongation time required for the DNA polymerases of T.thermophilus (Tth) and Pyrococcus furiosus (Pfu) to synthesise DNA fragments in PCRs. The presence of TthSSB increased the fidelity of the proof- reading-free DNA polymerase of T.thermophilus. TthSSB was also able to bind single-stranded RNA, allowing a dramatic enhancement of the reverse transcription activity of its cognate Tth DNA polymerase during cDNA synthesis.

Long-Term Enhancement of Neuronal Excitability and Temporal Fidelity Mediated by Metabotropic Glutamate Receptor Subtype 5

The cellular substrate for memory is generally attributed to long-lasting changes in synaptic strength. We report here that synaptic or pharmacological activation of the metabotropic glutamate receptor subtype 5 (mGluR5) induces long-term potentiation of intrinsic excitability (LTP-IE) in layer V pyramidal neurons. mGluR5-dependent LTP-IE was associated with a persistent reduction of the afterhyperpolarization (AHP) outward current (IAHP), resulting in the potentiation of EPSP-spike coupling. Apamin occluded induction of LTP-IE, indicating that downregulation of small conductance calcium-dependent potassium (SK) channels mediates this process. In addition to the improved reliability of the input-output function, LTP-IE led to increased temporal precision. The induced reduction of IAHP accelerated the rate of membrane depolarization preceding each action potential and subsequently decreased the jitter of the neuronal discharge. We conclude that mGluR5-dependent LTP-IE not only promotes the spread of excitation in the cortical network but also persistently enhances the temporal fidelity of the neuronal message.

Biochemical Assays of Gre Factors of Thermus Thermophilus

This chapter discusses the biochemical assaying of Gre factors of Thermus Thermophilus. The biochemical studies of Escherichia coli Gre factors indicate that they are not nucleases but RNAP co-factors, which activate the same catalytic center involved in both RNA synthesis and RNA hydrolysis reactions. The biological role of factor-induced endonucleolytic reaction includes: the enhancement of transcription fidelity, by helping RNAP excise misincorporated nucleotides; suppression of transcriptional pausing and arrest by reactivation of RNAP during reversible and irreversible backtracking; and stimulation of RNAP promoter escape and transition from initiation to elongation stage of transcription by helping the catalytic center reengage with nascent RNA 3´-terminus during abortive synthesis. The chapter describes four new methods useful for biochemical and structure-functional studies of Tth Gre factors: direct chromatographic assay for competitive binding of GreA1 and GreA2 to RNAP, specific transcript cleavage (misincorporation–excision) assay for GreA1, inhibition of RNA synthesis assay for GreA2, and localized Fe2 + -induced hydroxyl radical mapping of GreA1 and GreA2 sites proximal to RNAP catalytic center.

Calmodulin antagonists and cAMP inhibit ionizing-radiation-enhancement of double-strand-break repair in human cells

Ionizing radiation (IR) enhances double-strand-break (DSB)-repair fidelity in plasmids processed in normal lymphoblasts but not in lymphoblasts from ataxia telangiectasia (A–T) patients. Putatively, signal-transduction pathways mediate this DNA-repair induction. Because IR inhibition of DNA synthesis is defective in A–T cells and is mediated by a calmodulin (caM)-dependent pathway, we evaluated the involvement of caM-dependent pathways in DSB-repair induction. Human lymphoblasts were γ-irradiated with or without treatment with caM antagonists and the cells' abilities to repair shuttle pZ189 carrying a single DSB (linDNA) were assessed. In untreated controls, IR enhanced DSB-rejoining fidelity if transfection occurred promptly but diminished fidelity if transfection was delayed. Treatment with two caM antagonists, W-7 and W-13, prior to irradiation blocked this IR-enhancement of DSB-rejoining fidelity. Vinpocetine, a caM-dependent phosphodiesterase inhibitor, and 8-bromo-cAMP also inhibited IR enhancement of repair fidelity, but caM-dependent protein kinase II inhibitor KN62 had no effect. Other protein kinase inhibitors, staurosporine and genistein, also did not inhibit IR enhancement of DSB repair fidelity. However, staurosporine blocked the twofold reduction in DSB-repair fidelity seen if linDNA transfection was delayed 2 h after irradiation. These findings point to the involvement of caM/cAMP-dependent pathway(s) in mediating IR-enhancement of DSB-rejoining fidelity in mammalian cells.

Ionizing radiation enhances double-strand-break repair in rapamycin-treated ataxia telangiectasia lymphoblasts

Purpose : Unlike normal cells, ataxia telangiectasia (A-T) cells do not exhibit enhanced double-strand-break (dsb)-repair fidelity after ionizing radiation (IR) exposure. DNA-repair induction and other responses to IR are mediated by signalling pathways that are defective in A-T cells. Ataxia telangiectasia mutated (ATM) protein, the mutated protein in A-T cells, is homologous to members of the P13-kinase, including the rapamycin target FRAP. Rapamycin kills normal cells more readily in normal than in A-T cells, and inhibits the FRAP target p70 S6 kinase (p70 S6K) more readily in normal than in A-T cells. Also, PHAS-1, another FRAP target, may also be a substrate for ATM. Because ATM plays a role in the response of mammalian cells to rapamycin, the effect of rapamycin on IR enhancement of dsb repair was investigated. Materials and methods : Double-strand-break repair by normal and A-T lymphoblasts, either untreated or treated with rapamycin and gamma-irradiated, was analysed using shuttle pZ189 containing a dsb. Results : Double-strand-break-rejoining fidelity in linear plasmids (linDNA) processed in either untreated or rapamycin-treated normal cells increased about twofold if transfection occurred immediately after host irradiation. In contrast, radiation did not increase or decrease the repair fidelity by untreated A-T host cells. But, like normal hosts, dsb-repair fidelity improved twofold in A-T hosts treated with rapamycin. Treatment with the P13-kinase inhibitor LY294002 did not alter dsb-rejoining fidelity in normal or in A-T hosts. Conclusions : These findings demonstrate that rapamycin does not affect IR enhancement of dsb-repair fidelity in normal cells but restores this phenomenon in A-T lymphoblasts, and suggests the involvement of a rapamycin-sensitive pathway in radiation-enhanced dsb repair.

Distinct functions of N and C-terminal domains of GreA, an Escherichia coli transcript cleavage factor

The prokaryotic transcription factors GreA and GreB are involved in the regulation of transcript elongation by RNA polymerase (RNAP). Their known activities include suppression of transcription arrest, enhancement of transcription fidelity, and facilitation of the transition from abortive initiation to productive elongation. Presumably, Gre proteins exert their functions by altering the conformation of the enzyme in ternary elongation complexes (TEC) and inducing the cleavage of nascent RNA. GreA and GreB have a similar structural organization and consist of two domains: a C-terminal globular and an extended N-terminal coiled-coil domain. To investigate the functional roles of Gre domains, we expressed separately the N and C-terminal domains of GreA (NTD and CTD, respectively) and characterized their activities with in vitro assays. We demonstrate that the NTD possesses the residual transcript cleavage activity of the wild-type GreA. The CTD does not display any nucleolytic activity; however, it substantially increases the cleavage activity of the NTD. In contrast to NTD, the CTD competes with GreA and GreB for binding to RNAP and inhibits their transcript cleavage and antiarrest activities. Both domains individually and together inhibit transcription elongation. From these results we conclude that the NTD is responsible for the GreA induction of nucleolytic activity while the CTD determines the binding of GreA to RNAP. Both domains are required for full functional activity of GreA.

Domain Organization of Escherichia coli Transcript Cleavage Factors GreA and GreB

The GreA and GreB proteins of Escherichia coli induce cleavage of the nascent transcript in ternary elongation complexes of RNA polymerase. Gre factors are presumed to have two biologically important and evolutionarily conserved functions: the suppression of elongation arrest and the enhancement of transcription fidelity. A three-dimensional structure of GreB was generated by homology modeling on the basis of the known crystal structure of GreA. Both factors display similar overall architecture and surface charge distribution, with characteristic C-terminal globular and N-terminal coiled-coil domains. One major difference between the two factors is the "basic patch" on the surface of the coiled-coil domain, which is much larger in GreB than in GreA. In both proteins, a site near the basic patch cross-links to the 3' terminus of RNA in the ternary transcription complex. GreA/GreB hybrid molecules were constructed by genetic engineering in which the N-terminal domain of one protein was fused to the C-terminal domain of the other. In the hybrid molecules, both the coiled-coil and the globular domains contribute to specific binding of Gre factors to RNA polymerase, whereas the antiarrest activity and the GreA or GreB specificity of transcript cleavage is determined by the N-terminal domain. These results implicate the basic patch of the N-terminal coiled-coil domain as an important functional element responsible for the interactions with nascent transcript and determining the size of the RNA fragment to be excised during the course of the cleavage reaction.

Enhancement of lithographic patterns by using serif features

Serifs were designed for the thin-oxide level pattern of a CMOS SRAM cell with submicrometer design rules, using two-dimensional aerial image simulations for optimization. Results of experiments using I-line lithography showed good agreement with the simulations, and significant pattern shape improvement was observed when serifs were used. The proximity effects in the electron-beam mask-making process were found to reduce the full effectiveness of this technique due to the resulting deviations in serif sizes on the reticle. Further enhancement of pattern fidelity may be possible if this issue is resolved.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The single-stranded DNA-binding protein of Escherichia coli

The single-stranded DNA-binding protein (SSB) of Escherichia coli is involved in all aspects of DNA metabolism: replication, repair, and recombination. In solution, the protein exists as a homotetramer of 18,843-kilodalton subunits. As it binds tightly and cooperatively to single-stranded DNA, it has become a prototypic model protein for studying protein-nucleic acid interactions. The sequences of the gene and protein are known, and the functional domains of subunit interaction, DNA binding, and protein-protein interactions have been probed by structure-function analyses of various mutations. The ssb gene has three promoters, one of which is inducible because it lies only two nucleotides from the LexA-binding site of the adjacent uvrA gene. Induction of the SOS response, however, does not lead to significant increases in SSB levels. The binding protein has several functions in DNA replication, including enhancement of helix destabilization by DNA helicases, prevention of reannealing of the single strands and protection from nuclease digestion, organization and stabilization of replication origins, primosome assembly, priming specificity, enhancement of replication fidelity, enhancement of polymerase processivity, and promotion of polymerase binding to the template. E. coli SSB is required for methyl-directed mismatch repair, induction of the SOS response, and recombinational repair. During recombination, SSB interacts with the RecBCD enzyme to find Chi sites, promotes binding of RecA protein, and promotes strand uptake.

The single-stranded DNA-binding protein of Escherichia coli.

The single-stranded DNA-binding protein (SSB) of Escherichia coli is involved in all aspects of DNA metabolism: replication, repair, and recombination. In solution, the protein exists as a homotetramer of 18,843-kilodalton subunits. As it binds tightly and cooperatively to single-stranded DNA, it has become a prototypic model protein for studying protein-nucleic acid interactions. The sequences of the gene and protein are known, and the functional domains of subunit interaction, DNA binding, and protein-protein interactions have been probed by structure-function analyses of various mutations. The ssb gene has three promoters, one of which is inducible because it lies only two nucleotides from the LexA-binding site of the adjacent uvrA gene. Induction of the SOS response, however, does not lead to significant increases in SSB levels. The binding protein has several functions in DNA replication, including enhancement of helix destabilization by DNA helicases, prevention of reannealing of the single strands and protection from nuclease digestion, organization and stabilization of replication origins, primosome assembly, priming specificity, enhancement of replication fidelity, enhancement of polymerase processivity, and promotion of polymerase binding to the template. E. coli SSB is required for methyl-directed mismatch repair, induction of the SOS response, and recombinational repair. During recombination, SSB interacts with the RecBCD enzyme to find Chi sites, promotes binding of RecA protein, and promotes strand uptake.

Divergence in inflorescence height: An evolutionary response to pollinator fidelity.

The above-ground heights of inflorescences of 8 species of wild-flowers in a subalpine meadow in the Colorado Rocky Mountains were measured in two successive years. An index of overlap (of height-distributions) was computed for pairwise comparisons of all species. The species were assorted into 4 groups based on their usual pollinators: long-tongued bumblebees (3 species were pollinated by long-tongued bumblebees), short-tongued bumblebees (3 species), hummingbirds (1 species), and solitary bees (1 species). The values of the sample of overlap indices for plants pollinated by the same animals was significantly smaller than the values for plants pollinated by different animals; plants which share pollinators are less alike in height than those that don't share pollinators. It is suggested that this is a result of selection for enhancement of pollinator fidelity. The selective mechanisms, based on the 'horizontal' flight pattern of pollinators and the consequences to the plant of interspecific flights, are discussed.