915 research outputs found

    Time-optimal navigation through quantum wind

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    The quantum navigation problem of finding the time-optimal control Hamiltonian that transports a given initial state to a target state through quantum wind, that is, under the influence of external fields or potentials, is analysed. By lifting the problem from the state space to the space of unitary gates realising the required task, we are able to deduce the form of the solution to the problem by deriving a universal quantum speed limit. The expression thus obtained indicates that further simplifications of this apparently difficult problem are possible if we switch to the interaction picture of quantum mechanics. A complete solution to the navigation problem for an arbitrary quantum system is then obtained, and the behaviour of the solution is illustrated in the case of a two-level system

    Development of the Knowledge of Genome Sequencing (KOGS) questionnaire

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    OBJECTIVE: Whole-genome sequencing is being implemented in research and clinical care, yet tools to assess patients' knowledge are lacking. Our aim was to develop a robust measure of whole-genome sequencing knowledge suitable for patients and other stakeholders including research participants, public, students, and healthcare professionals. METHODS: An initial set of 17 items was developed via an iterative process including literature review, expert consultation, focus groups, and cognitive interviews with patients, and then administered to 243 individuals. We used exploratory factor analysis and item-response theory to confirm the psychometric suitability of the candidate items for assessing whole-genome sequencing knowledge. RESULTS: There was a strong main component after removing 5 items with low factor loadings. Item and scale homogeneity was achieved using Mokken scale analysis. Three further items were removed because they were misfits, inverse duplicates or resulted in local dependency. The remaining nine items fitted the two-parameter logistic IRT model which achieved excellent fit to the observed data. Cronbach's alpha was 0.79 indicating acceptable reliability. CONCLUSION: The KOGS, developed using a rigorous psychometric approach, is a brief and reliable tool. PRACTICE IMPLICATIONS: The KOGS may prove useful for researchers and healthcare professionals using whole-genome sequencing with patients and other stakeholders

    Routine provision of information on patient-reported outcome measures to healthcare providers and patients in clinical practice

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    This is the final version. Available from Cochrane Collaboration via the DOI in this record.This is the protocol for a review and there is no abstract. The objectives are as follows: To assess the impact of the routine use of patient-reported outcomes (PROs) in clinical practice on the process of care (including patient-physician communication, professionals awareness of patients' quality of life, diagnosis and recognition rates, treatment rates, health services and resource use, as well as patient behaviour); patients' and professionals' experiences of care; and health outcomes (both generic and disease-specific, using both routinely-used clinical measures and PROs).Spanish Ministry of ScienceInnovation and the European commissionNational Institutes of Health Research (NIHR

    Rapid testing and treatment for sexually transmitted infections improve patient care and yield public health benefits

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    A service evaluation of Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) testing and result notification in patients attending a rapid testing service (Dean Street Express [DSE]) compared with those attending an existing ‘standard’ sexual health clinic (56 Dean Street [56DS]), and modelling the impact of the new service from 1 June 2014 to 31 May 2015. Primary outcome: time from patients’ sample collection to notification of test results at DSE compared with 56DS. Secondary outcomes estimated using a model: number of transmissions prevented and the number of new partner visits avoided and associated cost savings achieved due to rapid testing at DSE. In 2014/15, there were a total of 81,352 visits for CT/NG testing across 56DS (21,086) and DSE (60,266). Rapid testing resulted in a reduced mean time to notification of 8.68 days: 8.95 days for 56DS (95% CI 8.91–8.99) compared to 0.27 days for DSE (95% CI 0.26–0.28). Our model estimates that rapid testing at DSE would lead to 196 CT and/or NG transmissions prevented (2.5–97.5% centile range = 6–956) and lead to annual savings attributable to reduced numbers of partner attendances of £124,283 (2.5–97.5% centile range = £4260–590,331). DSE, a rapid testing service for asymptomatic infections, delivers faster time to result notification for CT and/or NG which enables faster treatment, reduces infectious periods and leads to fewer transmissions, partner attendances and clinic costs

    Heterotic Black Horizons

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    We show that the supersymmetric near horizon geometry of heterotic black holes is either an AdS_3 fibration over a 7-dimensional manifold which admits a G_2 structure compatible with a connection with skew-symmetric torsion, or it is a product R^{1,1} * S^8, where S^8 is a holonomy Spin(7) manifold, preserving 2 and 1 supersymmetries respectively. Moreover, we demonstrate that the AdS_3 class of heterotic horizons can preserve 4, 6 and 8 supersymmetries provided that the geometry of the base space is further restricted. Similarly R^{1,1} * S^8 horizons with extended supersymmetry are products of R^{1,1} with special holonomy manifolds. We have also found that the heterotic horizons with 8 supersymmetries are locally isometric to AdS_3 * S^3 * T^4, AdS_3 * S^3 * K_3 or R^{1,1} * T^4 * K_3, where the radii of AdS_3 and S^3 are equal and the dilaton is constant.Comment: 35 pages, latex. Minor alterations to equation (3.11) and section 4.1, the conclusions are not affecte

    Geometric aspects of space-time reflection symmetry in quantum mechanics

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    For nearly two decades, much research has been carried out on properties of physical systems described by Hamiltonians that are not Hermitian in the conventional sense, but are symmetric under space-time reflection; that is, they exhibit PT symmetry. Such Hamiltonians can be used to model the behavior of closed quantum systems, but they can also be replicated in open systems for which gain and loss are carefully balanced, and this has been implemented in laboratory experiments for a wide range of systems. Motivated by these ongoing research activities, we investigate here a particular theoretical aspect of the subject by unraveling the geometric structures of Hilbert spaces endowed with the parity and time-reversal operations, and analyze the characteristics ofPT -symmetric Hamiltonians. A canonical relation between aPT -symmetric operator and a Hermitian operator is established in a geometric setting. The quadratic form corresponding to the parity operator, in particular, gives rise to a natural partition of the Hilbert space into two halves corresponding to states having positive and negative PT norm. Positive definiteness of the norm can be restored by introducing a conjugation operator C ; this leads to a positive-definite inner product in terms of CPT conjugation

    Topology of supersymmetric N=1, D=4 supergravity horizons

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    All supersymmetric N=1, D=4 supergravity horizons have toroidal or spherical topology, irrespective of whether the black hole preserves any supersymmetry.Comment: 17 pages, latex. Alterations to introduction and section 3.

    The factor structure of the Forms of Self-Criticising/Attacking & Self-Reassuring Scale in thirteen distinct populations

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    There is considerable evidence that self-criticism plays a major role in the vulnerability to and recovery from psychopathology. Methods to measure this process, and its change over time, are therefore important for research in psychopathology and well-being. This study examined the factor structure of a widely used measure, the Forms of Self-Criticising/Attacking & Self-Reassuring Scale in thirteen nonclinical samples (N = 7510) from twelve different countries: Australia (N = 319), Canada (N = 383), Switzerland (N = 230), Israel (N = 476), Italy (N = 389), Japan (N = 264), the Netherlands (N = 360), Portugal (N = 764), Slovakia (N = 1326), Taiwan (N = 417), the United Kingdom 1 (N = 1570), the United Kingdom 2 (N = 883), and USA (N = 331). This study used more advanced analyses than prior reports: a bifactor item-response theory model, a two-tier item-response theory model, and a non-parametric item-response theory (Mokken) scale analysis. Although the original three-factor solution for the FSCRS (distinguishing between Inadequate-Self, Hated-Self, and Reassured-Self) had an acceptable fit, two-tier models, with two general factors (Self-criticism and Self-reassurance) demonstrated the best fit across all samples. This study provides preliminary evidence suggesting that this two-factor structure can be used in a range of nonclinical contexts across countries and cultures. Inadequate-Self and Hated-Self might not by distinct factors in nonclinical samples. Future work may benefit from distinguishing between self-correction versus shame-based self-criticism.Peer reviewe

    Validation of key behaviourally based mental health diagnoses in administrative data: suicide attempt, alcohol abuse, illicit drug abuse and tobacco use

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    <p>Abstract</p> <p>Background</p> <p>Observational research frequently uses administrative codes for mental health or substance use diagnoses and for important behaviours such as suicide attempts. We sought to validate codes (<it>International Classification of Diseases, 9<sup>th </sup>edition, clinical modification </it>diagnostic and E-codes) entered in Veterans Health Administration administrative data for patients with depression versus a gold standard of electronic medical record text ("chart notation").</p> <p>Methods</p> <p>Three random samples of patients were selected, each stratified by geographic region, gender, and year of cohort entry, from a VHA depression treatment cohort from April 1, 1999 to September 30, 2004. The first sample was selected from patients who died by suicide, the second from patients who remained alive on the date of death of suicide cases, and the third from patients with a new start of a commonly used antidepressant medication. Four variables were assessed using administrative codes in the year prior to the index date: suicide attempt, alcohol abuse/dependence, drug abuse/dependence and tobacco use.</p> <p>Results</p> <p>Specificity was high (≥ 90%) for all four administrative codes, regardless of the sample. Sensitivity was ≤75% and was particularly low for suicide attempt (≤ 17%). Positive predictive values for alcohol dependence/abuse and tobacco use were high, but barely better than flipping a coin for illicit drug abuse/dependence. Sensitivity differed across the three samples, but was highest in the suicide death sample.</p> <p>Conclusions</p> <p>Administrative data-based diagnoses among VHA records have high specificity, but low sensitivity. The accuracy level varies by different diagnosis and by different patient subgroup.</p

    Stationary Black Holes: Uniqueness and Beyond

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    The spectrum of known black-hole solutions to the stationary Einstein equations has been steadily increasing, sometimes in unexpected ways. In particular, it has turned out that not all black-hole-equilibrium configurations are characterized by their mass, angular momentum and global charges. Moreover, the high degree of symmetry displayed by vacuum and electro-vacuum black-hole spacetimes ceases to exist in self-gravitating non-linear field theories. This text aims to review some developments in the subject and to discuss them in light of the uniqueness theorem for the Einstein-Maxwell system.Comment: Major update of the original version by Markus Heusler from 1998. Piotr T. Chru\'sciel and Jo\~ao Lopes Costa succeeded to this review's authorship. Significantly restructured and updated all sections; changes are too numerous to be usefully described here. The number of references increased from 186 to 32
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