233 research outputs found
Suppression of photon shot noise dephasing in a tunable coupling superconducting qubit
We demonstrate the suppression of photon shot noise dephasing in a
superconducting qubit by eliminating its dispersive coupling to the readout
cavity. This is achieved in a tunable coupling qubit, where the qubit frequency
and coupling rate can be controlled independently. We observe that the
coherence time approaches twice the relaxation time and becomes less sensitive
to thermal photon noise when the dispersive coupling rate is tuned from several
MHz to 22 kHz. This work provides a promising building block in circuit quantum
electrodynamics that can hold high coherence and be integrated into larger
systems
Digital quantum simulators in a scalable architecture of hybrid spin-photon qubits
Resolving quantum many-body problems represents one of the greatest
challenges in physics and physical chemistry, due to the prohibitively large
computational resources that would be required by using classical computers. A
solution has been foreseen by directly simulating the time evolution through
sequences of quantum gates applied to arrays of qubits, i.e. by implementing a
digital quantum simulator. Superconducting circuits and resonators are emerging
as an extremely-promising platform for quantum computation architectures, but a
digital quantum simulator proposal that is straightforwardly scalable,
universal, and realizable with state-of-the-art technology is presently
lacking. Here we propose a viable scheme to implement a universal quantum
simulator with hybrid spin-photon qubits in an array of superconducting
resonators, which is intrinsically scalable and allows for local control. As
representative examples we consider the transverse-field Ising model, a spin-1
Hamiltonian, and the two-dimensional Hubbard model; for these, we numerically
simulate the scheme by including the main sources of decoherence. In addition,
we show how to circumvent the potentially harmful effects of inhomogeneous
broadening of the spin systems
Clinical trial metadata:Defining and extracting metadata on the design, conduct, results and costs of 125 randomised clinical trials funded by the National Institute for Health Research Health Technology Assessment programme
Background: Â By 2011, the Health Technology Assessment (HTA) programme had published the results of over 100 trials with another 220 in progress. The aim of the project was to develop and pilot âmetadataâ on clinical trials funded by the HTA programme. Â Objectives: The aim of the project was to develop and pilot questions describing clinical trials funded by the HTA programme in terms of it meeting the needs of the NHS with scientifically robust studies. The objectives were to develop relevant classification systems and definitions for use in answering relevant questions and to assess their utility. Â Data sources: Published monographs and internal HTA documents. Â Review methods: A database was developed, âpopulatedâ using retrospective data and used to answer questions under six prespecified themes. Questions were screened for feasibility in terms of data availability and/or ease of extraction. Answers were assessed by the authors in terms of completeness, success of the classification system used and resources required. Each question was scored to be retained, amended or dropped. Â Â Results: One hundred and twenty-five randomised trials were included in the database from 109 monographs. Neither the International Standard Randomised Controlled Trial Number nor the term ârandomised trialâ in the title proved a reliable way of identifying randomised trials. Only limited data were available on how the trials aimed to meet the needs of the NHS. Most trials were shown to follow their protocols but updates were often necessary as hardly any trials recruited as planned. Details were often lacking on planned statistical analyses, but we did not have access to the relevant statistical plans. Almost all the trials reported on cost-effectiveness, often in terms of both the primary outcome and quality-adjusted life-years. The cost of trials was shown to depend on the number of centres and the duration of the trial. Of the 78 questions explored, 61 were well answered, 33 fully with 28 requiring amendment were the analysis updated. The other 17 could not be answered with readily available data. Â Limitations: The study was limited by being confined to 125 randomised trials by one funder. Â Conclusions: Metadata on randomised controlled trials can be expanded to include aspects of design, performance, results and costs. The HTA programme should continue and extend the work reported here
Disease activity and cognition in rheumatoid arthritis : an open label pilot study
Acknowledgements This work was supported in part by NIHR Newcastle Biomedical Research Centre. Funding for this study was provided by Abbott Laboratories. Abbott Laboratories were not involved in study design; in the collection, analysis and interpretation of data; or in the writing of the report.Peer reviewedPublisher PD
Upregulation of Transglutaminase andΔ(γ-Glutamyl)-Lysine in the Fisher-Lewis Rat Model of Chronic Allograft Nephropathy
Background. Tissue transglutaminase (TG2), a cross-linking enzyme, modulates deposition of extracellular matrix protein in renal fibrosis. This study aimed to examine TG2 and its cross-link product Δ(γ-glutamyl)-lysine in the Fisher-Lewis rat renal transplantation (RTx) model of chronic allograft nephropathy (CAN). Materials and Methods. Left renal grafts from male Fisher and Lewis were transplanted into Lewis rats, generating allografts and isografts, respectively. Blood pressure, renal function, and proteinuria were monitored for up to 52 weeks. At termination, CAN was assessed in the renal tissue by light and electron microscopy, TG2 and Δ(γ-glutamyl)-lysine by immunofluorescence, and the urinary Δ(γ-glutamyl)-lysine by high performance liquid chromatography.
Results. Compared to the isograft, the allografts were hypertensive, proteinuric, and uraemic and developed CAN. Extracellular TG2 (glomerulus: 64.55 + 17.61 versus 2.11 + 0.17, P<0.001; interstitium: 13.72 + 1.62 versus 3.19 + 0.44, P<0.001), Δ(Îł-glutamyl)-lysine (glomerulus: 21.74 + 2.71 versus 1.98 + 0.37, P<0.01; interstitium: 37.96 + 17.06 versus 0.42 + 0.11, P<0.05), TG2 enzyme activity (1.09 + 0.13 versus 0.41 + 0.03 nmol/h/mg protein, P<0.05), TG2 mRNA (20-fold rise), and urinary Δ(Îł-glutamyl)-lysine (534.2 + 198.4ânmol/24âh versus 57.2 + 4.1ânmol/24âh,P<0.05) levels were significantly elevated in the allografts and showed a positive linear correlation with tubulointerstitial fibrosis. Conclusion. CAN was associated with upregulation of renal TG2 pathway, which has a potential for pharmacological intervention. The elevated urinary Δ(Îł-glutamyl)-lysine, measured for the first time in RTx, is a potential biomarker of CA
Understanding assurance in the Australian self-managed superannuation fund industry
Abstract
Using proprietary data, this study examines auditor industry specialisation, professional brand effects and non-audit services (NAS) in the self-managed superannuation fund (SMSF) sector, the fastest growing and largest segment of the Australian $1.75 trillion retirement savings industry. We consider the impact of industry leadership for a large sample of SMSF audits for the three years to June 2010. After controlling for factors known to determine audit fees, we find evidence of fee discounting for the leading suppliers of SMSF audits, consistent with Simunic (1980)âs assertion of competition in the small audit client market. When considering the impact of professional affiliations, we find that registered company auditors and members of professional bodies who comply with auditing and ethical standards receive a fee premium. In terms of auditor independence, the supply of NAS is shown to improve the auditorsâ ability to report breaches, suggesting no independence concerns arising from joint supply of audit and NAS in this setting
Using the seven-step method to reduce defects in a polymer sheet making process
Thesis (M.S.)--Massachusetts Institute of Technology, Sloan School of Management, 1994, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1994.Includes bibliographical references (leaves 87-88).by Michael A. Raftery.M.S
The Mass Distribution of Stellar-Mass Black Holes
We perform a Bayesian analysis of the mass distribution of stellar-mass black
holes using the observed masses of 15 low-mass X-ray binary systems undergoing
Roche lobe overflow and five high-mass, wind-fed X-ray binary systems. Using
Markov Chain Monte Carlo calculations, we model the mass distribution both
parametrically---as a power law, exponential, gaussian, combination of two
gaussians, or log-normal distribution---and non-parametrically---as histograms
with varying numbers of bins. We provide confidence bounds on the shape of the
mass distribution in the context of each model and compare the models with each
other by calculating their relative Bayesian evidence as supported by the
measurements, taking into account the number of degrees of freedom of each
model. The mass distribution of the low-mass systems is best fit by a
power-law, while the distribution of the combined sample is best fit by the
exponential model. We examine the existence of a "gap" between the most massive
neutron stars and the least massive black holes by considering the value, M_1%,
of the 1% quantile from each black hole mass distribution as the lower bound of
black hole masses. The best model (the power law) fitted to the low-mass
systems has a distribution of lower-bounds with M_1% > 4.3 Msun with 90%
confidence, while the best model (the exponential) fitted to all 20 systems has
M_1% > 4.5 Msun with 90% confidence. We conclude that our sample of black hole
masses provides strong evidence of a gap between the maximum neutron star mass
and the lower bound on black hole masses. Our results on the low-mass sample
are in qualitative agreement with those of Ozel, et al (2010).Comment: 56 pages, 22 figures, 9 tables, as accepted by Ap
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