CRYSTAL STRUCTURE STUDIES ON SOME DEHYDROPEPTIDES

Queen Mary College, Londo

Vertical Cavity Surface-Emitting Lasers Operating with Multiple Photonic Crystal Defect Cavities

Coherently coupled arrays of vertical cavity surface emitting lasers (VCSELs) offer the potential of extended area coherent sources with high spectral purity, useful in a variety of applications in the high power (laser radar, optical communications, steerable sources) and low power (image processing, spectroscopic sensing, optical logic) regimes. A recently developed method for providing optical confinement is the introduction of a two-dimensional photonic crystal (PhC) pattern with a defect, etched into the top distributed Bragg reflector, to define a defect cavity in a VCSEL. This dissertation investigates the operation of PhC VCSELs that have multiple defect cavities to form arrays of vertically emitting lasers. A major achievement of this work is coherent coupling between the defect cavities, with both out-of-phase and in-phase coherent coupling in 2x1 and 2x2 defect cavity arrays. A qualitative and quantitative understanding of the optical characteristics of PhC VCSEL arrays was developed and demonstrated by the agreement of simulated to experiment results. Other conclusions that are supported by this study are: (1) different wafers result in coupling at different overlap integral values; (2) coupling can be effected by thermal effects (hysteresis observed), and (3) the relative phase difference between the defect civilities can be varied with injection current during both continuous-wave and pulsed operatio

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

Treatment success in pragmatic randomised controlled trials: a review of trials funded by the UK Health Technology Assessment programme

<p>Abstract</p> <p>Background</p> <p>Previous research reviewed treatment success and whether the collective uncertainty principle is met in RCTs in the US National Cancer Institute portfolio. This paper classifies clinical trials funded by the UK HTA programme by results using the method applied to the US Cancer Institute trials, and compares the two portfolios.</p> <p>Methods</p> <p>Data on all completed randomised controlled trials funded by the HTA programme 1993-2008 were extracted. Each trial's primary results was classified into six categories; 1) statistically significant in favour of the new treatment, 2) statistically significant in favour of the control treatment 3) true negative, 4) truly inconclusive, 5) inconclusive in favour of new treatment or 6) inconclusive in favour of control treatment. Trials were classified by comparing the 95% confidence interval for the difference in primary outcome to the difference specified in the sample size calculation. The results were compared with Djulbegovic's analysis of NCI trials.</p> <p>Results</p> <p>Data from 51 superiority trials were included, involving over 48,000 participants and a range of diseases and interventions. 85 primary comparisons were available because some trials had more than two randomised arms or had several primary outcomes. The new treatment had superior results (whether significant or not) in 61% of the comparisons (52/85 95% CI 49.9% to 71.6%). The results were conclusive in 46% of the comparisons (19% statistically significant in favour of the new treatment, 5% statistically significant in favour of the control and 22% true negative). The results were classified as truly inconclusive (i.e. failed to answer the question asked) for 24% of comparisons (20/85). HTA trials included fewer truly inconclusive and statistically significant results and more results rated as true negative than NCI trials.</p> <p>Conclusions</p> <p>The pattern of results in HTA trials is similar to that of the National Cancer Institute portfolio. Differences that existed were plausible given the differences in the types of trials -HTA trials are more pragmatic. The results indicate HTA trials are compatible with equipoise. This classification usefully summarises the results from clinical trials and enables comparisons of different portfolios of trials.</p

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:  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 ‘metadata’ on clinical trials funded by the HTA programme.   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.   Data sources: Published monographs and internal HTA documents.   Review methods: A database was developed, ‘populated’ 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.    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 ‘randomised trial’ 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.   Limitations: The study was limited by being confined to 125 randomised trials by one funder.   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

Assessing the impact of England's National Health Service R&D Health Technology Assessment program using the "payback" approach

Copyright © Cambridge University Press 2009Objectives: This study assesses the impact of the English National Health Service (NHS) Health Technology Assessment (HTA) program using the "payback" framework.Methods: A survey of lead investigators of all research projects funded by the HTA program 1993-2003 supplemented by more detailed case studies of sixteen projects.Results: Of 204 eligible projects, replies were received from 133 or 65 percent. The mean number of peer-reviewed publications per project was 2.9. Seventy-three percent of projects claimed to have had had an impact on policy and 42 percent on behavior. Technology Assessment Reports for the National Institute for Health and Clinical Excellence (NICE) had fewer than average publications but greater impact on policy. Half of all projects went on to secure further funding. The case studies confirmed the survey findings and indicated factors associated with impact.Conclusions: The HTA program performed relatively well in terms of "payback." Facilitating factors included the program's emphasis on topics that matter to the NHS, rigorous methods and the existence of "policy customers" such as NICE

A Modified Single Defect Cavity Study for Coherent Coupling in Photonic Crystal VCSELs

A modified single defect cavity study was conducted to determine if a calibrated simplified model could be use to predict and subsequently design for coherent coupling in PhC VCSELs. Modeled and fabricated devices are compared

Inconsistency lemmas in algebraic logic

In this paper, the inconsistency lemmas of intuitionistic and classical propositional logic are formulated abstractly. We prove that, when a (finitary) deductive system is algebraized by a variety K, then has an inconsistency lemma—in the abstract sense—iff every algebra in K has a dually pseudo-complemented join semilattice of compact congruences. In this case, the following are shown to be equivalent: (1) has a classical inconsistency lemma; (2) has a greatest compact theory and K is filtral, i.e., semisimple with EDPC; (3) the compact congruences of any algebra in K form a Boolean lattice; (4) the compact congruences of any A ∈ K constitute a Boolean sublattice of the full congruence lattice of A. These results extend to quasivarieties and relative congruences. Except for (2), they extend even to protoalgebraic logics, with deductive filters in the role of congruences. A protoalgebraic system with a classical inconsistency lemma always has a deduction-detachment theorem (DDT), while a system with a DDT and a greatest compact theory has an inconsistency lemma. The converses are false.http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1521-3870hb201

The economics of psychiatric services in the UK and Ireland, 1845-1985.

This study empirically describes the activity and costs associated with the psychiatric services in England & Wales, Scotland & Ireland from 1845 to 1985. Basic economic concepts are employed to structure data. Key hypotheses from the three historical schools (Progressive, Social Control and Epidemiological) are tested, using a neo-Popperian methodology. The literature is reviewed in Chapter 2 (general and socio-economic) and Chapter 3 (epidemiological). Chapter 4 sets the comparative legal and financing context. Chapters 5, 6 and 7 outline activity and financial data for each country. Major points common to each included: - relative stability in admissions and costs up to around 1945, - a major change after 1945 when admission rates (both first and total) rose sharply, - inflows exceeded outflows until around 1955 when the number of resident inpatients began to fall, - despite the fall in resident inpatients, spending, which was predominantly publicly financed and hospital orientated, continued to increase. Chapter 8 suggests that three hypotheses were not obviously falsified by the data: - a pharmacological hypothesis linking new drugs in the mid-1950s to the changes which occurred then, - Wagner's Law, which predicts continued high levels of spending despite reductions in hospital places, and - Hare's epidemiological hypothesis which relied on the increase in first admission rates between 1850 and 1900. Four other hypotheses related to costs were rejected. Three paradoxes are identified for further investigation. Chapter 9 shows that the decline in the stock of inpatients occurred almost entirely in the long-stay (over 5 years) group, due mainly to deaths rather than live discharges. This pattern helps explain the continued high levels of spending. Ireland's outlier status is linked to both demand and supply side factors. Chapter 10 draws some overall conclusions and offers priorities for further research