14 research outputs found

    Survey of Period Variations of Superhumps in SU UMa-Type Dwarf Novae

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    We systematically surveyed period variations of superhumps in SU UMa-type dwarf novae based on newly obtained data and past publications. In many systems, the evolution of superhump period are found to be composed of three distinct stages: early evolutionary stage with a longer superhump period, middle stage with systematically varying periods, final stage with a shorter, stable superhump period. During the middle stage, many systems with superhump periods less than 0.08 d show positive period derivatives. Contrary to the earlier claim, we found no clear evidence for variation of period derivatives between superoutburst of the same object. We present an interpretation that the lengthening of the superhump period is a result of outward propagation of the eccentricity wave and is limited by the radius near the tidal truncation. We interpret that late stage superhumps are rejuvenized excitation of 3:1 resonance when the superhumps in the outer disk is effectively quenched. Many of WZ Sge-type dwarf novae showed long-enduring superhumps during the post-superoutburst stage having periods longer than those during the main superoutburst. The period derivatives in WZ Sge-type dwarf novae are found to be strongly correlated with the fractional superhump excess, or consequently, mass ratio. WZ Sge-type dwarf novae with a long-lasting rebrightening or with multiple rebrightenings tend to have smaller period derivatives and are excellent candidate for the systems around or after the period minimum of evolution of cataclysmic variables (abridged).Comment: 239 pages, 225 figures, PASJ accepte

    Erratum to: Methods for evaluating medical tests and biomarkers

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    [This corrects the article DOI: 10.1186/s41512-016-0001-y.]

    Evidence synthesis to inform model-based cost-effectiveness evaluations of diagnostic tests: a methodological systematic review of health technology assessments

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    Background: Evaluations of diagnostic tests are challenging because of the indirect nature of their impact on patient outcomes. Model-based health economic evaluations of tests allow different types of evidence from various sources to be incorporated and enable cost-effectiveness estimates to be made beyond the duration of available study data. To parameterize a health-economic model fully, all the ways a test impacts on patient health must be quantified, including but not limited to diagnostic test accuracy. Methods: We assessed all UK NIHR HTA reports published May 2009-July 2015. Reports were included if they evaluated a diagnostic test, included a model-based health economic evaluation and included a systematic review and meta-analysis of test accuracy. From each eligible report we extracted information on the following topics: 1) what evidence aside from test accuracy was searched for and synthesised, 2) which methods were used to synthesise test accuracy evidence and how did the results inform the economic model, 3) how/whether threshold effects were explored, 4) how the potential dependency between multiple tests in a pathway was accounted for, and 5) for evaluations of tests targeted at the primary care setting, how evidence from differing healthcare settings was incorporated. Results: The bivariate or HSROC model was implemented in 20/22 reports that met all inclusion criteria. Test accuracy data for health economic modelling was obtained from meta-analyses completely in four reports, partially in fourteen reports and not at all in four reports. Only 2/7 reports that used a quantitative test gave clear threshold recommendations. All 22 reports explored the effect of uncertainty in accuracy parameters but most of those that used multiple tests did not allow for dependence between test results. 7/22 tests were potentially suitable for primary care but the majority found limited evidence on test accuracy in primary care settings. Conclusions: The uptake of appropriate meta-analysis methods for synthesising evidence on diagnostic test accuracy in UK NIHR HTAs has improved in recent years. Future research should focus on other evidence requirements for cost-effectiveness assessment, threshold effects for quantitative tests and the impact of multiple diagnostic tests

    Erratum to: Methods for evaluating medical tests and biomarkers

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    [This corrects the article DOI: 10.1186/s41512-016-0001-y.]

    Observing variable stars

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    L’osservazione delle stelle variabili

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    L’osservazione delle stelle variabili è uno dei principali contributi che gli astronomi dilettanti possono offrire alla scienza e questo libro fornisce tutte le informazioni necessarie per dedicarvisi con profitto. Nella prima parte vengono presentate in dettaglio le diverse classi di variabili, con esempi, curve di luce e descrizioni fisiche. La seconda sezione copre invece tutti gli aspetti pratici dell’osservazione: dalla preparazione e la pianificazione, alle tecniche osservative, fino alla gestione e all’elaborazione dei dati. Questo è un volume indispensabile e completo per chi voglia impegnarsi nell’osservazione delle stelle variabili, adatto per tutti gli astrofili, dai principianti fino a quelli che hanno già maturato un discreto livello d’esperienza e di abilità

    Primary Care Consultations About Medically Unexplained Symptoms: How Do Patients Indicate What They Want?

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    BACKGROUND: Patients with medically unexplained physical symptoms (MUS) are often thought to deny psychological needs when they consult general practitioners (GPs) and to request somatic intervention instead. We tested predictions from the contrasting theory that they are transparent in communicating their psychological and other needs. OBJECTIVE: To test predictions that what patients tell GPs when they consult about MUS is related transparently to their desire for (1) emotional support, (2) symptom explanation and (3) somatic intervention. DESIGN: Prospective naturalistic study. Before consultation, patients indicated what they wanted from it using a self-report questionnaire measuring patients' desire for: emotional support, explanation and reassurance, and physical investigation and treatment. Their speech during consultation was audio-recorded, transcribed and coded utterance-by-utterance. Multilevel regression analysis tested relationships between what patients sought and what they said. PARTICIPANTS: Patients (N = 326) consulting 33 GPs about symptoms that the GPs designated as MUS. RESULTS: Patients who wanted emotional support spoke more about psychosocial problems, including psychosocial causes of symptoms and their need for psychosocial help. Patients who wanted explanation and reassurance suggested more physical explanations, including diseases, but did not overtly request explanation. Patients' wish for somatic intervention was associated only with their talk about details of such interventions and not with their requests for them. CONCLUSIONS: In general, patients with medically unexplained symptoms provide many cues to their desire for emotional support. They are more indirect or guarded in communicating their desire for explanation and somatic intervention
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