A Phoma Disease of Lavender. Studies from the Pathological Laboratory: II

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Ratcheting up ambition on climate policy

The historic Paris Agreement aims to constrain the peak increase in global mean temperature to 1.5 °C, or at least well below 2 °C. Every country has committed to device their own “nationally determined contributions” towards this target. These contributions are only proscribed for the coming 10-15 years with a regular reassessment of them against the global target. Here we use a global climate-economy model to explore consequences of differing levels of ambition during these reanalysis. We find that without substantially increased ambition the probability of avoiding 2 °C of warming is marginal. We present several plausible future trajectories that significantly increase the probability of avoiding 2 °C, but are unable to keep global temperatures below 1.5 °C. We advocate countries engage in the reassessment process soon and with high ambitions as catastrophic climate change can effectively be ruled out by such actions

Amplitude-mode dynamics of polariton condensates

We study the stability of collective amplitude excitations in non-equilibrium polariton condensates. These excitations correspond to renormalized upper polaritons and to the collective amplitude modes of atomic gases and superconductors. They would be present following a quantum quench or could be created directly by resonant excitation. We show that uniform amplitude excitations are unstable to the production of excitations at finite wavevectors, leading to the formation of density-modulated phases. The physical processes causing the instabilities can be understood by analogy to optical parametric oscillators and the atomic Bose supernova.Comment: 4 pages, 2 figure

Creation of entangled states in coupled quantum dots via adiabatic rapid passage

Quantum state preparation through external control is fundamental to established methods in quantum information processing and in studies of dynamics. In this respect, excitons in semiconductor quantum dots (QDs) are of particular interest since their coupling to light allows them to be driven into a specified state using the coherent interaction with a tuned optical field such as an external laser pulse. We propose a protocol, based on adiabatic rapid passage, for the creation of entangled states in an ensemble of pairwise coupled two-level systems, such as an ensemble of QD molecules. We show by quantitative analysis using realistic parameters for semiconductor QDs that this method is feasible where other approaches are unavailable. Furthermore, this scheme can be generically transferred to some other physical systems including circuit QED, nuclear and electron spins in solid-state environments, and photonic coupled cavities.Comment: 10 pages, 2 figures. Added reference, minor changes. Discussion, results and conclusions unchange

Constructing Mutually Unbiased Bases in Dimension Six

The density matrix of a qudit may be reconstructed with optimal efficiency if the expectation values of a specific set of observables are known. In dimension six, the required observables only exist if it is possible to identify six mutually unbiased complex 6x6 Hadamard matrices. Prescribing a first Hadamard matrix, we construct all others mutually unbiased to it, using algebraic computations performed by a computer program. We repeat this calculation many times, sampling all known complex Hadamard matrices, and we never find more than two that are mutually unbiased. This result adds considerable support to the conjecture that no seven mutually unbiased bases exist in dimension six.Comment: As published version. Added discussion of the impact of numerical approximations and corrected the number of triples existing for non-affine families (cf Table 3

Middlesex University’s Invisque visual analytics tool: supported by text analytics techniques from the University of Leeds

This report describes the joint entry from Middlesex University and the University of Leeds for Mini Challenge 3 for the VAST Challenge 2011. In order to address the challenge question, the primary tool we used was Middlesex University’s Interactive Visual Search and Query Environment (INVISQUE), which served as the user interface to the Mini-Challenge 3 news corpus. INVISQUE was supported by corpus text analytics from the University of Leeds, which provided additional information that was visualised on the INVISQUE user interface

How standard is standard care? Exploring control group outcomes in behaviour change interventions for young people with type 1 diabetes

Objective: Poor descriptions of standard care may compromise interpretation of results in randomised controlled trials (RCTs) of health interventions. We investigated quality of standard care in RCTs of behaviour change interventions for young people with type 1 diabetes and consider implications for evaluating trial outcomes. Design: We conducted systematic searches for articles published between 1999 and 2012. We extracted standard care descriptions and contacted trial authors to complete a checklist of standard care activities. The relationship between standard care quality and outcomes was examined via subgroup meta-analyses and meta-regression. Main outcome measures: Standard care descriptions, standard care quality, and relationships between standard care quality with medical and psychological outcomes. Results: We identified 20 RCTs described across 26 articles. Published descriptions of standard care were limited to service-level features. Author responses indicated standard care provision extended beyond published accounts. Subgroup analyses suggested control groups receiving higher standard care quality showed larger improvements in both medical and psychological outcomes, although standard care quality did not predict outcomes significantly. Conclusion: The quality of care delivered to control group participants can influence outcomes of RCTs. Inadequate reporting exacerbates this issue by masking variations between trials. We argue for increased clarity in reporting standard care in future trials